Process and apparatus for heat-setting twist of yarn

Abstract

 A process of having a yarn (13) twisted while the yarn (13) is traveling along a yarn travel path and then heat-treating the twisted yarn (13) to have the twist of the yarn (13) heat-set, comprising the steps of: having the twisted yarn (13) held in contact with a liquidized fluid (18) of heat conductivity higher than that of air and imparting the liquidized fluid (18) to the twisted yarn (13), and heating the twisted yarn (13) and the liquidized fluid (18) imparted to the twisted yarn (13) to a degree that the twist of the yarn (13) is heat-set.

Description

FIELD OF THE INVENTION

[0001] The present invention relates to a process of and an apparatus for heat-treating a yarn continuously twisted while the yarn is traveling along a yarn traveling path to heat-set the twist of the yarn on the traveling path, and in particular to a process of and an apparatus for heat-treating a twisted yarn, such as for instance a hard twist yarn, made of polyethylene terephthalate to heat-set the twist of the yarn.

DESCRIPTION OF THE PRIOR ART

[0002] In general, a woven fabric requires a yarn imparted many turns of twist for the purpose of making the yarn excellent in feeling when it is made into the fabric. For preventing snarls (kinky thread) from being generated in the looming process of the yarn resulting from many turns of twist, for example more than 600 turns per meter imparted to the yarn, it is necessary for the twisted yarn to be heat-treated until residual torque remaining in the twist of the yarn is partly removed to a torque (residual torque level) causing no trouble to the twisted yarn in the looming process.

[0003] As this kind of yarn twist setting process there has been generally employed a steam box process which comprises the steps of winding the twisted yarn on a flanged bobbin and the like having a number of bores, accommodating the flanged bobbin with the twisted yarn in a steam box, filling the steam box with steam of the temperature of 60 - 80 °C after gas in the steam box being expelled and vacuumized, and leaving the flanged bobbin with the twisted yarn in the steam box for a time interval of 30 to 60 minutes to heat-set the twist of the yarn.

[0004] As a process tentatively carried out for heat-setting the twist of the yarn, there has recently been well known in the art a process disclosed in Japanese Patent Laid-open Publication No. 60-162821, which is called "continuation process" (dry type). The continuation process comprises the steps of continuously traveling the twisted yarn, and heating the traveling twisted yarn with a dry heater of the contact or non-contact type for heat-setting the twist of the yarn.

[0005] The steam box process, however, has encountered the following problems. (A1) There has been caused difference in the set twist of the yarn between the core and surface portions of the yarn package on the flanged bobbin. Such a yarn different in the set twist tends to cause so-called "uneven luster" in the fabric made of the yarn, thereby resulting in unacceptable products. (A2) In order to reduce the difference in the set twist of the yarn between the core and surface portions of the yarn package, there may be proposed an idea for making the yarn package small. This idea entails the process less effective and thus makes products costly. (A3) The steam box process is required to be carried out in a discontinuous manner, thereby necessitating a yarn rewinding step and thus making the apparatus expensive.

[0006] The continuation process is continuously performed and thus has no such problems as causing the difference in the set twist of the yarn between the core and surface portions of the yarn package in the steam box process.

[0007] This continuation process is, however, most likely to provoke some undesirable problems as follows. (B1) Air which is of relatively low heat conductivity (0.026 kcal/m.h. deg. : 80 °C) exists between monofilaments forming the twisted yarn. Therefore, it takes a long time to raise the temperatures of the filaments to predetermined levels uniform at the core and surface portions of the monofilaments. (B2) The heat conductivity of the monofilaments forming the yarn is 0.04 kcal/m.h. deg., a relatively low level which causes the difference in the set twist of the yarn between the core and surface portions of the yarn, thereby resulting in making the feeling of the yarn produced by this continuation process inferior to that of the yarn produced by the steam box process.

[0008] In view of the foregoing steam box process and the continuation process, there has recently been proposed a process disclosed in Japanese Provisional Patent Publication No. 6-63127. The process is continuously performed by a steam heater having a steam chamber designed to accommodate steam and to have the yarn pass therethrough with the steam held in contact with the yarn.

[0009] This steam heating process is, however, most likely to provoke some undesirable problems as follows. (C1) The steam in the steam chamber is apt to be changed to dew drops in the steam chamber. (C2) The dew drops cause the yarn to be unevenly heat-set and are required to be drained away from the steam chamber.

[0010] The present invention contemplates provision of improved process and apparatus for heat-setting the twist of a yarn overcoming the drawbacks of the prior-art process and apparatus of the described general natures.

[0011] The present inventors are of the notion that the reason why the yarn twisted and heat-set by the previously mentioned dry continuation process is inferior in feeling to the yarn heat-set by the conventional steam box process may stem from air heated at a high temperature. In general, the yarn is constituted by monofilaments containing therein air having heat conductivity of 0.026kcal/m.h. deg. at its temperature of 80 °C or 0.032kcal/m.h. deg. at its temperature of 180 °C which is relatively low. Moreover, the heat conductivity of the monofilaments itself is roughly 0.04 kcal/m.h. deg. which is also relatively low. As the heating medium for heating the yarn is constituted by air, this air cannot be rapidly expelled from space between the monofilaments even if the yarn traveling on the above heater is heated to a high temperature, thereby resulting in heat transmission being carried out through the filaments and air contained therein. It takes much time to evenly heat the yarn at a predetermined temperature from the surface portion of the yarn to the core portion of the yarn. If the heater is heated to a high temperature enough to raise the temperature of the core portion of the yarn for a short time interval for heat-setting the core portion of the yarn, the surface portion of the yarn is excessively heated to bring the temperature and the heat-set twist of the surface portion at excessively high levels. This results in inferior feeling to the twisted yarn produced by the conventional steam box process.

[0012] In contrast, a liquidized fluid such as for example water or hot water can readily expel air between the monofilaments of the yarn simply under its capillary phenomenon if the yarn is immersed in the liquidized fluid. Incidentally, the heat conductivity of water is 0.511 kcal/m.h. deg. at its temperature of 20 °C or 0.578 kcal/m.h. deg. at its temperature of 80 °C which indicates approximately 20 times as large as that of air maintained at its temperature of 80 °C.

[0013] The foregoing facts let the present inventors come to reach a conclusion that there can be produced a twisted yarn having even heat-set twist between the core portion and the surface portion of the yarn through the steps of having the monofilaments of the yarn held in contact with (for example immersed in or coated by) a material of high heat conductivity or a fluid of high heat conductivity which can easily penetrate into the monofilaments of the yarn so that there is no difference in heat distribution between the core and surface portions of the yarn during heat-treatment of the yarn. This process proposed in the above by the present inventors makes it possible to remove the step of rewinding the yarn on the bobbin.

[0014] It is therefore an object of the present invention to provide a process of and an apparatus for continuously producing a twisted yarn having feeling commensurate with that of the twisted yarn produced by the conventional steam box process through the step of heating the twisted yarn while it is continuously traveling, and imparting to the twisted yarn a material of high heat conductivity such as hot water having a high heat conductivity (0.578kcal/m.h. deg. (80 °C hot water)) roughly 20 times that of air, or hot water containing a small amount of oiling liquid.

SUMMARY OF THE INVENTION

[0015] According to a first aspect of the present invention there is provided a process of having a yarn twisted while the yarn is traveling along a yarn travel path and then heat-treating the twisted yarn to have the twist of the yarn heat-set, comprising the steps of: having the twisted yarn held in contact with a liquidized fluid of heat conductivity higher than that of air and imparting the liquidized fluid to the twisted yarn, and heating the twisted yarn and the liquidized fluid imparted to the twisted yarn to a degree that the twist of the yarn is heat-set.

[0016] According to a second aspect of the present invention there is provided a process of having a yarn twisted while the yarn is traveling along a yarn travel path and then heat-treating the twisted yarn to have the twist of the yarn heat-set, comprising the steps of: heating a liquidized fluid of heat conductivity higher than that of air to a degree that the liquidized fluid is hot enough to heat-set the twist of the yarn, and having the twisted yarn held in contact with the heated liquidized fluid to impart the heated liquidized fluid to the yarn and heat-setting the twist of the yarn by the heated liquidized fluid.

[0017] According to a third aspect of the present invention there is provided an apparatus for having a yarn twisted while the yarn is traveling along a yarn travel path and heat-treating the twisted yarn to have the twist of the yarn heat-set, comprising: yarn traveling means for traveling the yarn along the yarn travel path, yarn twisting means for twisting the yarn on the yarn travel path, fluid imparting means for imparting a liquidized fluid to the twisted yarn on the yarn travel path by holding the twisted yarn in contact with the liquidized fluid of heat conductivity higher than that of air, and yarn heating means for heating the twisted yarn on the yarn travel path and the liquidized fluid imparted to the twisted yarn to a degree that the twist of the yarn is heat-set.

[0018] The yarn contacting time for imparting the fluid medium to the yarn is preferably from 0.1 to 90 seconds in view of operation efficiency of the apparatus and heat-setting efficiency of the yarn since uneven residual torque remains in the heat-set twisted yarn if the yarn contacting time is below 0.1 second. The lower limit temperature of the heated liquidized fluid is preferably above 60 °C since it is impossible for the twisted yarn to be effectively heat-set if the temperature of the heated liquidized fluid is below 50 °C. The upper limit temperature of the heated liquidized fluid is preferably below 100 °C since hot water is used as a fluid for easy handling. A small amount of oiling liquid may be contained in the hot water.

[0019] Incidentally, the twisted yarn may be temporarily heat-set to have a residual torque small enough to prevent any trouble to the following process. The twisted yarn may be heated with a fluid of high heat conductivity being between the monofilaments forming the twisted yarn. The twisted yarn can be therefore heated rapidly to its core portion, thereby resulting in evenly distributed temperature from the core portion to the surface portion of the twisted yarn and evenly heat-setting the twist of the yarn. The twisted yarn thus heat-set has no different in the set twist between the core and surface portions of the yarn and therefore has a feeling commensurate with that of the yarn produced by the conventional steam box process.

[0020] According to a fourth aspect of the present invention there is provided a process of having a yarn made mainly of polyethylene terephthalate twisted while the yarn is traveling along a yarn travel path and then heat-treating the yarn to have the twist of the yarn heat-set, comprising the steps of: having the twisted yarn held in contact with a liquidized fluid of heat conductivity higher than that of air for 0.1 to 90 seconds and imparting the liquidized fluid to the twisted yarn, and heating the twisted yarn and the liquidized fluid imparted to the twisted yarn to a temperature of 60 to 100 °C to heat-set the twist of the yarn.

[0021] According to a fifth aspect of the present invention there is provided a process of having a yarn made mainly of polyethylene terephthalate twisted while the yarn is traveling along a yarn travel path and then heat-treating the yarn to have the twist of the yarn heat-set, comprising the steps of: heating a liquidized fluid of heat conductivity higher than that of air to a temperature of 60 to 100 °C, and having the twisted yarn held in contact with the heated liquidized fluid for 0.1 to 90 seconds to impart the heated liquidized fluid to the yarn and heat-setting the twist of the yarn by the heated liquidized fluid.

[0022] The twisted yarn is immersed in the liquidized fluid heated at the temperature of 60 to 100 °C for the time interval of 0.1 to 90 seconds to heat-set the twist of the yarn, thereby enabling the liquidized fluid to rapidly penetrate into the core and surface portions of the yarn. Air is rapidly expelled from space between the monofilaments of the twisted yarn by the liquidized fluid, thereby enabling the liquidized fluid to rapidly penetrate into the core and surface portions of the yarn. Consequently, the core and surface portions of the twisted yarn are rapidly and evenly heated, and the yarn is thus evenly heat-set.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The features and advantages of the present invention will be more clearly understood from the following description taken in conjunction with the accompanying drawings in which:

Fig. 1 is a view of the whole construction of one embodiment of an apparatus for heat-setting the twist of a yarn according to the invention, which performs a yarn twist imparting and heat-setting process,

Fig. 2 is a schematic view of the essential parts of another embodiment of the apparatus for heat-setting the twist of the yarn according to the invention, which performs a yarn twist imparting and heat-setting process,

Fig. 3 is a view of the whole construction of a yarn twist setting apparatus suitable for performing one embodiment of a process of heat setting the twist of a yarn according to the present invention,

Fig. 4 is a schematic view of the construction of one embodiment of an apparatus used for conducting the experiment of the heat-setting process according to the invention,

Fig. 5 is an explanatory view for explaining the method of measuring the torque of the yarn,

Fig. 6 is a schematic view of an apparatus used for conducting the experiment of a conventional dry type of heat-setting process,

Fig. 7 is a graph showing residual torques of heat-set yarns representing the heat-set effects performed by the first experimental example of the heat-setting process according to the present invention and by the comparative example of the conventional dry type of heat-setting process,

Fig. 8 is a graph showing residual torques of heat-set yarns representing the heat-set effects performed by the second and third experimental examples of the heat-setting process according to the present invention and the second comparative example of the conventional dry type of heat-setting process,

Fig. 9 is a graph showing residual torques of heat-set yarns representing the heat-set effects performed by the fourth to seventh experimental examples of the heat-setting process according to the present invention,

Fig. 10 is a graph showing residual torques of heat-set yarns representing the heat-set effects performed by the eighth to tenth experimental examples of the heat-setting process according to the present invention,

Fig. 11 is a graph showing residual torques of heat-set yarns different in their twist numbers and representing the heat-set effects performed by the eleventh experimental example of the heat-setting process according to the present invention,

Fig. 12 is a graph showing heat-set effects shown in Fig. 11 with residual torque ratio,

Fig. 13 is a graph showing residual torques of heat-set yarns applied different tensions during the heat-treatment and representing the heat-set effects performed by the twelfth experimental-example of the heat-setting process according to the present invention, and

Fig. 14 is a cross-sectional view of essential parts forming a modification of the twist setting apparatus suitable for performing above embodiments of the heat-setting process according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Referring to Fig. 1 of the drawings, a first preferable embodiment of an apparatus for heat-setting the twist of a yarn will be described hereinlater in detail.

[0025] The twist setting apparatus embodying the present invention is shown as comprising a yarn twisting unit 1 which is constructed by a known double twister or the like for imparting many turns of twist, e.g., not less than 600 turns per meter. The yarn twisting unit 1 has a yarn twisting spindle 11 and a yarn supply package container 12 supported on the yarn twisting spindle 11 to contain a yarn supply package and a hollow spindle (not shown in the drawing) therein. The yarn supply package container 12 is adapted to supply the yarn 13 from the yarn supply package to the yarn twisting spindle 11 through the above hollow spindle to twist the yarn by the hollow spindle. The yarn twisting spindle 11 is adapted to impart double or multiple twist to the yarn 13 by additionally twisting the yarn 13 by means of the hollow spindle. The yarn 13 additionally twisted by the yarn twisting spindle 11 is fed from the yarn twisting spindle 11 to a feed roller couple 15 through a snail guide 14. The feed roller couple 15 is constituted by a pair of rollers 15a and 15b which are held in rolling contact with each other to feed the yarn 13 to a liquid reservoir 16.

[0026] The liquid reservoir 16 is designed to accommodate therein a predetermined fluid 18 such as for example water, hot water, thermal liquid medium and others which are hereinafter referred to as a "liquid" for simplicity. The liquid reservoir 16 is so constructed as to adjust the temperature of the liquid 18 in a well known manner and is designed to rotatably support a yarn treating roller 17 immersed in the liquid 18 and rotated by the yarn 13 traveling in contact with the yarn treating roller 17. The yarn treating roller 17 is designed to be movable vertically in the fluid 18 to enable the length of the yarn 13 immersed in the liquid 18 to be adjusted. The above liquid reservoir 16 and the liquid 18 collectively constitute fluid imparting means 2 for imparting a liquidized fluid to the twisted yarn 13 and absorbing the liquidized fluid 18 to the twisted yarn 13. The liquid reservoir 16 with the heated liquid 18 constitutes yarn heating means for heating the yarn 13 to a degree that the yarn 13 is heat-set.

[0027] The yarn 13 passing through the liquid 18 in the liquid reservoir 16 is introduced to a drawing roller couple 19, a compressed air unit 20, a yarn heater 21, and a yarn cooling unit 22 before being wound into a yarn package 24 by a yarn winding machine 23. The yarn winding machine 23 is constituted by a winding roller 23a held in frictional contact with the yarn package 24 and a pair of cradle arms 23b adapted to rotatably support the yarn package 24 thereon. The drawing roller couple 19 is constituted by a pair of rollers 19a and 19b which are held in rolling contact with each other to have the liquid 18 partly wrung out from the yarn 13 to be uniformly adhered and absorbed to the yarn 13. The drawing roller couple 19 is so constructed as to have the number of its rotation per minute varied to adjust the time interval of the yarn 13 immersed in and passing through the liquid 18 of the liquid reservoir 16 and to have the tension of the yarn 13 traveling through the liquid 18 adjusted in cooperation with the feed roller couple 15. The yarn 13 between the feed roller couple 15 and the drawing roller couple 19 is guided and firmly retained by the yarn treating roller 17 and the roller couples 15 and 19 so that the yarn 13 is introduced into the liquid reservoir 16 with a predetermined tension.

[0028] According to the present invention, the drawing roller couple 19 may be replaced with a suitable wiper for wiping part of the liquid 18 adhered to the yarn 13. The compressed air unit 20 is formed with a cylindrical bore adjustably opened and closed at its longitudinal ends to allow the yarn 13 to pass therethrough, and has a plurality of air nozzles opened at the cylindrical bore to have compressed air blown to the yarn 13, thereby removing part of the liquid 18 from the yarn 13 and enabling the yarn 13 to have an appropriate amount of liquid in the yarn 13. The yarn heater 21 is well known in construction having a cylindrical form or a U-shape and including known heating means such as for example a sheathed heater or a resistive wire heater while being adjusted by known temperature controlling means. The heating means may be constituted by a microwave heater designed to heat the yarn 13 by means of microwaves (high frequency electromagnetic waves). The yarn heater 21 is adjustable in position with respect to and supported on a frame structure not shown in the drawings. The yarn heater 21 can be heated for heat-setting the twist of the yarn 13 and for drying the yarn 13 while the yarn 13 is passing through the yarn heater 21. The yarn cooling unit 22 is of roughly same construction as that of the compressed air unit 20 and is thus designed to blow compressed air to the yarn 13 heated at a high temperature by the yarn heater 21 so that the yarn 13 is cooled off by the yarn cooling unit 22. The yarn winding machine 23 is of friction drive type which can wind the yarn 13 until it is wound into a full yarn package 24. The feed roller couple 15, the drawing roller couple 19 and the yarn winding machine 23 collectively define yarn transfer ring means for transferring the yarn on its predetermined yarn travel path.

[0029] The steps of one embodiment of a process for heat setting the twist of the yarn according to the present invention will be herein-later described together with the apparatus previously mentioned in accordance with Fig. 1 of the drawings. The yarn heater 21 is not operated when the process is carried out.

[0030] The yarn supply package container 12 is firstly prepared and positioned on the yarn twist spindle 11. The yarn 13 is fed from the yarn supply package container 12 to be passed through the yarn twist spindle 11 and then hooked to the snail guide 14, the feed roller couple 15, the yarn treating roller 17, the drawing roller couple 19, the compressed air unit 20, the yarn heater 21, the yarn cooling unit 22 and the yarn winding machine 23. The leading end of the yarn 13 is finally wound on a bobbin forming the core of the yarn package 24 and not shown in the drawings.

[0031] In advance of the operation of the twist imparting and heat-setting apparatus, the heated liquidized fluid 18 such as hot water, or hot water with a slight amount of oil which is selected in view of the property and propensity of the yarn 13 is accumulated in the liquid reservoir 16 and then heated to raise its temperature to a predetermined heat-treating temperature. The yarn treating roller 17 is then moved vertically to its predetermined position adjusted for the length of the yarn 13 to be immersed in the heated liquidized fluid 18 of the liquid reservoir 16. The drawing roller couple 19 is then adjusted for its rotation per minute to be set at a predetermined value suitable for the yarn 13 to travel in the heated liquidized fluid 18 at a suitable time interval for heat-setting the twist of the yarn 13.

[0032] During the operation of the twist imparting and heat-setting apparatus, the yarn 13 is fed from the yarn supply package container 12 and then twisted in succession by the yarn twisting spindle 11. The twisted yarn 13 is then introduced to the heated liquidized fluid 18 of the liquid reservoir 16 through the snail guide 14 and the feed roller couple 15 and subsequently to the drawing roller couple 19. When the twisted yarn 13 is passed around the yarn treating roller 17 through the heated liquidized fluid 18 of the liquid reservoir 16 at a predetermined time interval, the heated liquidized fluid 18 is penetrated into the twisted yarn 13 formed by monofilaments which allow the liquid medium 18 to permeate therebetween under the capillary phenomenon so that the twisted yarn 13 is heated by the heated liquidized fluid 18 uniformly and rapidly to a predetermined temperature irrespective of the core and surface portions of the twisted yarn 13, thereby ensuring heat-setting of the twisted yarn 13. It is thus to be understood that the twisted yarn 13 is by no means uneven nor different in its twist setting between the core and surface portions of the yarn 13.

[0033] The yarn 13 passing through the liquid 18 of the liquid reservoir 16 is dragged out by the drawing roller couple 19 from the liquid reservoir 16 and then introduced to the compressed air unit 20 where the liquid 18 is removed from the yarn 13 by the compressed air. The yarn 13 passing through the compressed air unit 20 is then introduced to the yarn cooling unit 22 where the yarn 13 is cooled and sufficiently dried. The yarn 13 is then wound until it is formed into a full yarn package 24 at a predetermined winding speed by the yarn winding machine 23.

[0034] As will be understood from the previously stated in the present embodiment, the twisted yarn 13 is heat-treated by the heated liquidized fluid 18 for heat-setting its twist while being passed through the heated liquidized fluid 18 at the predetermined time interval to have the monofilaments forming the yarn 13 heated uniformly so that the twisted yarn 13 is by no means uneven nor different in its twist setting between the core and surface portions of the yarn 13. This means that the twisted yarn 13 having same feeling as that produced by the conventional steam box process can be continuously produced. As a result, the yarn package 24 comes to have core and surface portions formed with the yarn uniform in twist setting, thereby enabling the twisted yarn to be supplied to a loom or a knitting machine without any troubles and making it possible to reduce the steps of rewinding the twisted yarn required for the conventional steam box process and to produce the present apparatus at a relatively low cost.

[0035] The steps of another embodiment of the heat-setting process according to the present invention will be hereinlater described together with the apparatus previously mentioned in accordance with Fig. 1 of the drawings. The yarn heater 21 or other yarn heating means for heating the yarn 13 and the fluid 18 imparted to the yarn 13 is operated when the process is carried out.

[0036] A predetermined amount of the liquidized fluid 18 such as for example water or hot water is accumulated in the liquid reservoir 16. The yarn heater 21 constituting the heating means is also heated to a predetermined temperature.

[0037] During the operation of the twist imparting and heat-setting apparatus, the yarn 13 continuously twisted is introduced into the liquidized fluid 18 of the liquid reservoir 16 and then dragged out by the drawing roller couple 19. The liquidized fluid 18 serves to force air out of space between the monofilaments forming the twisted yarn 13 and penetrates into the yarn 13 under the capillary phenomenon.

[0038] The yarn 13 passing through the liquidized fluid 18 is dragged out from the liquid reservoir 16 by the drawing roller couple 19 where the yarn 13 is slightly wrung to be penetrated with a uniform amount of liquidized fluid 18. The yarn 13 is fed to the compressed air unit 20 where a residual liquidized fluid adhered to the yarn 13 is removed to give an appropriate amount of liquidized fluid 18 to the yarn 13. The yarn 13 is then supplied to the yarn heating unit 21 and directly or indirectly heated by the yarn heating unit 21. At this time, the yarn 13 is heated rapidly and uniformly by the yarn heating unit 21 irrespective of the core and surface portions of the yarn 13 to impart the twist setting to the yarn 13 by the reason that the liquidized fluid 18 absorbed in the yarn 13 is of heat conductivity relatively high compared with that of air. This means that the twisted yarn 13 is substantially by no means different in its twist setting between the core and surface portions of the yarn 13.

[0039] The yarn 13 heated for heat-setting its twist by the yarn heating unit 21 is then introduced to the yarn cooling unit 22 where the liquidized fluid 18 imparted to the yarn 13 is completely removed by compressed air and the yarn 13 is cooled and dried. The yarn 13 is then wound until it is formed into a full yarn package 24 at a predetermined winding speed by the yarn winding machine 23.

[0040] As will be understood from the previously stated in the present embodiment of the heat-setting process, the twisted yarn 13 is passed through the liquidized fluid 18 at a predetermined time interval to have liquidized fluid 18 penetrate into space between the monofilaments forming the yarn 13 and heat-treated by the yarn heating unit 21 so that the twisted yarn 13 is heated rapidly and uniformly to the core portion of the yarn 13 and thus by no means uneven nor different in its twist setting between the core and surface portions of the yarn 13. This means that the twisted yarn 13 having same feeling as that produced by the conventional steam box process can be continuously produced.

[0041] Another embodiment of the twist setting apparatus according to the present invention will be hereinlater described in accordance with Fig. 2 illustrating essential parts constituting the apparatus. The present embodiment differs from the above one embodiment of the twist setting apparatus only in the fluid imparting means and is same in other constitutional elements or parts as those of the one embodiment so that the following will be described only on those different fluid imparting means with the reference numerals being given with the same reference numerals as those of the one embodiment and with omitting description on the same elements or parts.

[0042] There are shown in Fig. 2 a fluid reservoir 36, a first roller 31 partly immersed in a fluid 18 such as water or hot water accumulated in the fluid reservoir 36, and a second roller 32 constituting a contact roller held in frictional contact with the first roller 31 to have the first roller 31 driven. The first roller 31, the second roller 32 and the fluid reservoir 36 collectively constitute fluid imparting means 30 for imparting the fluid 18 to the twisted yarn 13 by coating. The yarn 13 is twisted by the yarn twisting spindle 11 constituting yarn twisting means. The first roller 31 constituting a yarn treating roller serves to impart the fluid 18 to the yarn 13 on its periphery exposed to the air, and have the fluid 18 absorbed in the yarn 13 while the yarn 13 is passing around the yarn treating roller 31. The second roller 32 is adapted to have the twisted yarn 13 pass between the first roller 31 and the second roller 32 for evenly imparting the liquid 18 to the yarn 13. The first and second rollers 31 and 32 concurrently constitute yarn transferring means together with the feed roller unit 15 and the yarn winding machine 23 for transferring the yarn 13. The yarn 13 supplied from the yarn supply package container 12 and twisted by the yarn twisting spindle 11 is introduced into the fluid 18 on the first roller 31 through slits 36a and 36b formed in the fluid reservoir 36 by the first and second rollers 31 and 32, and then to the yarn winding machine 23 by way of the compressed air unit 20, the yarn heating unit 21 and the yarn cooling unit 22 to be wound into the full yarn package 24 in a manner similar to that described in the previously mentioned embodiment.

[0043] The steps of one embodiment of the heat-setting process performed by the foregoing apparatus according to the present invention will be hereinlater described.

[0044] In advance of the operation of the twist imparting and heat-setting apparatus, the fluid 18 of the fluid reservoir 36 is selectively heated to a predetermined temperature in compliance with the property and propensity of the yarn 13. The first roller 31 is set to have a predetermined number of rotation per minute so that the time interval to have the yarn 13 held in contact with the first roller 31 is adjusted to have the fluid 18 sufficiently adhered to the yarn 13 from the surface portion to the core portion thereof. The yarn heating unit 21 is adapted to heat the yarn to a predetermined heat-treating temperature.

[0045] During the operation of the twist imparting and heat-setting apparatus, the yarn 13 continuously twisted comes to be in contact with the first roller 31, and the fluid 18 is imparted to the yarn 13 by the first roller 31 rotated counterclockwise in Fig. 2. The fluid 18 is adhered to and absorbed in the yarn 13 which is then transferred to the contact area of the first and second rollers 31 and 32 where the fluid 18 is absorbed into the monofilaments forming the yarn 13 under the capillary phenomenon with air in the monofilaments expelled therefrom, thereby enabling the fluid 18 to uniformly be adhered to and absorbed in the monofilaments of the yarn 13. The yarn 13 passing through the first and second rollers 31 and 32 is transferred to the compressed air unit 20 where residual fluid on the yarn 13 is removed to impart an appropriate amount of fluid to the yarn 13. The yarn 13 is subsequently traveled to the yarn heating unit 21 where the yarn 13 is directly or indirectly heated to a predetermined temperature. At this time, the yarn 13 is heated uniformly and rapidly by the yarn heating unit 21 for heat-setting the twist of the yarn irrespective of the core and surface portions of the yarn 13 due to the fluid 18 having conductivity relatively high compared with that of air and penetrated into the monofilaments of the yarn 13. In consequence, there is by no means uneven and different twists between the core and surface portions of the yarn 13.

[0046] As will be understood from the previously stated in the present embodiment, the twisted yarn 13 is passed in contact with the fluid 18 without passing through the fluid 18 of the reservoir 16 to have the liquid 18 penetrate into the monofilaments forming the yarn 13 and heated by the yarn heating unit 21 so that the twisted yarn 13 is heated rapidly and uniformly to the core portion of the yarn 13 and thus by no means uneven nor different in its twist setting between the core and surface portions of the yarn 13. This means that the twisted yarn 13 having same feeling as that produced by the conventional steam box process can be continuously produced.

[0047] While there have been described in the above about the first roller 31 partly immersed in the fluid 18 in the liquid reservoir 16 as one of the fluid imparting means for imparting the fluid to the yarn 13, the first roller 31 may be replaced by a fluid atomizer for atomizing fluid to the yarn 13, or a fluid nozzle formed in the yarn guide for blowing fluid to the yarn 13, and a yarn guide supplied with fluid for imparting the fluid while the yarn 13 is passing over the yarn guide. The yarn cooling unit may be replaced by an air nozzle type, a cooling plate type, and a naturally cooling type which can render almost the same effect to the twisted yarn.

[0048] The heat-setting process performed by the foregoing apparatus may comprises the steps of raising the temperature of the liquidized fluid 18 to a predetermined yarn treating temperature by heating one of the liquidized fluid 18 and the first roller 31 to produce a heating liquidized fluid 18 which is to be held in contact with the twisted yarn on the first roller 31. In this case, the yarn 13 is heated by the heating liquidized fluid 18 when the heating liquidized fluid 18 is adhered to the yarn 13 on the peripheral surface of the first roller 31 where the temperature of the heating liquidized fluid 18 is high enough to heat-treat the yarn 13 at the predetermined heat-treating temperature. Preferably, the first roller 31 is heated to the predetermined heat-treating temperature. The heating liquidized fluid 18 is removed from the yarn 13 by the compressed air unit 20. In this case, the yarn heating unit 21 and the compressed air unit 22 may be unnecessary.

[0049] By the reason that the yarn 13 twisted and continuously traveling is held in contact with the heating liquidized fluid 18 to have the fluid penetrate into monofilaments forming the yarn 13 and to have the yarn 13 heated to a predetermined temperature according to the present invention, the yarn 13 can be readily imparted with the fluid 18 of high heat conductivity and also can be heated readily to the core portion of the yarn 13. In addition, there is no difference in the twist setting between the core and surface portions of the yarn 13, thereby making it possible to produce evenly heat-set the twist of yarn 13 which is same in feeling as those produced by the conventional steam box process.

[0050] Fig. 3 shows one embodiment of an apparatus for heat-setting the twist of a yarn which is operated to perform a process of heat-setting the twist of the yarn according to the present invention.

[0051] The twist setting apparatus is shown in Fig. 3 as comprising a yarn twisting unit 41 which is constructed by a known double twister or the like for imparting many turns of twist, e.g., not less than 600 turns per meter. The yarn twisting unit 41 has a yarn twisting spindle 51 and a yarn supply package container 52 supported on the yarn twisting spindle 51 to contain a yarn supply package and a hollow spindle (not shown in the drawing) therein. The yarn supply package container 52 is adapted to supply the yarn 53 from the yarn supply package to the yarn twisting spindle 51 through the above hollow spindle to twist the yarn by the hollow spindle. The yarn twisting spindle 51 is adapted to doubly or multiply twist the yarn 53 by additionally twisting the yarn 53 twisted by the hollow spindle. The yarn 53 additionally twisted by the yarn twisting spindle 51 is fed from the yarn twisting spindle 51 to a feed roller couple 55 through a snail guide 54. The feed roller couple 55 is constituted by a pair of rollers 55a and 55b which are held in rolling contact with each other to adjust the tension of the yarn 53 to be fed to the following step such as for example a yarn winding step. The yarn 53 is guided and firmly retained by the rollers 55a and 55b of the feed roller couple 55 while being held in contact with the right peripheral surface of the roller 55a and the left peripheral surface of the roller 55b of the feed roller couple 55 in Fig. 3. The yarn 53 is then introduced into a liquid reservoir 56 after passing through the feed roller couple 55. The yarn supply package container 52 has a yarn 53 of for example 92de/36Fil (denier/monofilament) made mainly of polyethylene terephthalate which is simply referred to as "PET" in the drawings.

[0052] The liquid reservoir 56 is designed to accommodate therein a predetermined liquid 58 such as for example water, hot water, thermal liquid medium and others which are hereinafter referred to as a "liquid" for simplicity. The liquid reservoir 56 is so constructed as to adjust the temperature of the liquid 58 in a well known manner and is designed to rotatably support a yarn treating roller 57 immersed in the liquid 58 and rotated by the yarn 53 traveling in contact with the yarn treating roller 57. The yarn treating roller 57 is designed to be movable vertically in the fluid 58 to enable the length of the yarn 53 immersed in the liquid 58 to be adjusted. In other words, the fluid imparting means 42 may be operated to have the twisted yarn 53 immersed in the liquidized fluid 58 at a predetermined immersed time varied in response to the position of the yarn treating roller 57. The immersed time may be varied in the range of 0.1 to 90 seconds. The yarn 53 passing through the liquid 58 in the liquid reservoir 56 is introduced to a drawing roller couple 59, a compressed air unit 60, and a yarn heater 61 before being wound into a yarn package 64 by a yarn winding machine 63.

[0053] The drawing roller couple 59 is constituted by a pair of rollers 59a and 59b which are held in rolling contact with each other to have the liquid 58 partly wiped out from and uniformly adhered to the yarn 53. The drawing roller couple 59 is so constructed as to have the number of its rotation per minute varied to adjust the time interval of the yarn 53 immersed in and passing through the liquid 58 of the liquid reservoir 56. The yarn 53 is immersed in the liquid 58 maintained at a predetermined heat-treating temperature for a predetermined time interval by traveling the yarn 53 on a yarn travel path adjusted to have a predetermined length for a predetermined time interval. The drawing roller couple 59 is designed to have the tension of the yarn 53 traveling through the liquid 58 adjusted in cooperation with the feed roller couple 55. According to the present invention, the drawing roller couple 59 may be replaced with a suitable wiper for wiping part of the liquid 58 adhered to and absorbed in the yarn 53.

[0054] The compressed air unit 60 is formed with a cylindrical bore adjustably opened and closed at its longitudinal ends to allow the yarn 53 to pass therethrough and has a plurality of air nozzles opened at the cylindrical bore to have compressed air blown to the yarn 53, thereby removing the liquid 58 from the surface of the yarn 53. The yarn heater 61 is well known in construction having a cylindrical form or a U-shape and heated by known heating means such as for example a sheathed heater, a resistive metal wire heater or a microwave heater while being adjusted by known temperature controlling means. The yarn heater 61 is adjustable in position with respect to and supported on a frame structure not shown in the drawings. The yarn heater 61 can be heated for drying the yarn 53 while the yarn 53 is passing through the yarn heater 61. The dried yarn 53 is wound by a well known friction type of yarn winding machine 63 until it is formed into a full yarn package 64 with the help of its friction roller 63a held in pressing contact with the yarn package 64. The yarn package 64 is rotatably supported by a pair of cradle arms 63b of the yarn winding machine 63.

[0055] One example of the yarn twist process will be hereinlater described together with the operation of the twist setting apparatus which performs the process of heat-treating the twist of the yarn 53.

[0056] In advance of performing the present example of the yarn twist process, a yarn will be described in the following about the heat-set twist of the yarn which has a twist number (twist turns per meter) of 1500 turn/meter (indicated simply by "T/M") and a torque (hereinlater referred to as a residual torque) at 20 percentage.

[0057] Initially, the yarn supply package container 52 having a yarn 53 wound thereon is prepared with the adjustment of the drawing roller couple 59 in the speed of its rotation to have the twist number of the yarn 53, twisted by the yarn twist spindle 51 set at the speed of rotation of 10,000 r.p.m., set at about 1,500 T/M. The yarn supply package container 52 is then placed on the yarn twist spindle 51 to have the yarn 53 fed from the yarn supply package container 52 to the drawing roller couple 59 by way of the snail guide 54, the feed roller 55 and the yarn treating roller 57. The yarn 53 is then introduced to the compressed air unit 60 and the yarn heater 61 before being wound into the yarn package 64 by the yarn winding machine 63 while being in frictional contact with the friction roller 63a of the yarn winding machine 63.

[0058] In advance of the operation of the yarn twist setting apparatus, a test yarn was produced through the steps of driving the yarn twist spindle 51, the feed roller 55, the drawing roller and the yarn winding machine 63 without the liquid 58 being housed in the reservoir 56 to form a full yarn package 64 made of a predetermined amount of yarn 53 having no heat-set twist, and unwinding the yarn 53 having no heat-set twist from the yarn winding machine. When the torque of the test yarn 53 and the twist number of twist of the test yarn 53 were measured, their values were 85T/M and 1492 T/M, respectively.

[0059] The residual torque of the test yarn 53 is set at


in order to set the residual torque of the heat-set test yarn 53 heat-set at 20 percentage. For obtaining the results of experiments stated in detail in Fig. 9, the following conditions were decided.

[0060] If the turns per meter of the yarn 53 given by the yarn twist spindle 51 having a capacity of 2 x 10000 T/min is 1500 T/M, the traveling speed of the yarn 53 is


The yarn treating roller 57 is vertically moved in the fluid reservoir 56 until it assumes a vertical position optimum for the traveling yarn 53 to pass through the liquid 58 maintained at a predetermined heat-treating temperature at a heat-treatment time interval (hereinafter referred to simply as "heat-set time") corresponding to a heat-treatment temperature (hereinafter referred to simply as "heat-set temperature").

[0061] The above conditions results in a desirable heat-set effect as indicated in the following table.

Heat Set Temperature	Heat Set Time (Distance in Fluid)
100 °C	0.25 sec (- - - -)
95 °C	1.0 sec ( 22 cm )
92. 5 °C	1.5 sec ( 33 cm )
90 °C	2.5 sec ( 55 cm )

[0062] The following procedure is carried out through the steps of accommodating a predetermined amount of liquid 58 in the fluid reservoir 56, raising the temperature of the liquid 58 to any one of the temperatures as set forth in the above table, and vertically moving the yarn treating roller 57 to adjust the length of the travel path of the yarn 53 in the liquid 58 to the distance corresponding to the heat-set time to have the yarn 53 pass through the liquid 58 at the heat-set time as indicated in the above table.

[0063] When the apparatus then starts to be operated, the drawing roller couple 59 is rotated at a predetermined speed of rotation to have the yarn 53 travel at a travel speed of 0.22 m/sec and to have the tension of the yarn 53 adjusted at a predetermined value in cooperation with the feed roller couple 55. The yarn 53 is continuously twisted to have a twist number of 1500 T/ M. The yarn 53 thus twisted is then fed to and drawn by the drawing roller couple 59 by way of the snail guide 54, the feed roller couple 55 and the yarn treating roller 57 while being held in contact with the yarn treating roller 57 and immersed in the liquid 58 of the fluid reservoir 56. The twisted yarn 53 is immersed in the liquid 58 which is of a heat conductivity excessively higher than that of air while being passing through the liquid 58 maintained at the heat-treatment temperature at the predetermined time so that the air between the monofilaments is expelled by the liquid 58 or under the influence of capillary phenomenon of the liquid 58 to have the liquid 58 penetrate into the twisted yarn 53 and filled from the surface portion of the yarn 53 to the core portion of the yarn 53. The twisted yarn 53 is thus rapidly heated to the predetermined heat-set temperature while being immersed in the liquid 58 for the predetermined heat-set time to have the temperatures of the core and surface portions of the twisted yarn 53 evenly raised. This results in the even heat-set twist of the yarn 53 between the core and surface portions of the yarn 53.

[0064] The twisted yarn 53 is then drawn by the drawing roller couple 59 from the liquid 58 of the fluid reservoir 56 and fed to the cooling unit 60 where the residual liquid 58 (high conductivity material) adhered to the twisted yarn 53 is removed and cooled by the compressed air blown to the twisted yarn 53. In the event that the twisted yarn 53 is needed to be dried, the heating unit 61 is operated to have the twisted yarn 53 dried while being passing through the heating unit 61. Thereafter, the yarn 53 is wound into a yarn package at a predetermined winding speed by the yarn winding machine 63.

[0065] The yarn thus wound by the yarn winding machine 63 is heat-set to have a residual torque of 20 percentage without twist heat-set difference between the core and surface portions of the yarn 53 of the yarn package 64 and with a feeling commensurate with that of the yarn produced by the steam box process. The yarn package 64 can be operated by the conventional loom or the conventional knitting machine without any trouble to ensure a desirable feeling in the product made by those machines.

[0066] The above advantageous effect available in the process according to the present invention can be secured even in the predetermined ranges of the heat-set temperature and the heat-set time which are varied.

[0067] The ranges of the heat-set temperature and the heat-set time thus available in the process according to the present invention are confirmed through repeated experiments made by the present inventor, and will be hereinlater described in detail. The above experiments were conducted through a test apparatus which can be operated under almost the same condition as that of the yarn twist setting apparatus previously mentioned. The test apparatus is constructed as shown in Fig. 4.

[0068] The test apparatus is illustrated in Fig. 4 as being constructed by a gadget 71. The gadget 71 comprises a supporting member 71a having a pair of leg portions 71b and 71c secured at their upper ends to the supporting member 71a in spaced relationship to each other in the longitudinal direction of the supporting member 71a, and a plurality of pulleys 73 rotatably supported on a shaft extending perpendicularly to the supporting member 71a and secured to one leg portion 71b of the supporting member 71a. The gadget 71 further comprises a plate member 74 securely supported on the other leg portion 71c of the supporting member 71a in parallel relationship with the shaft having the pulleys 73 rotatably supported. The above gadget 71 is prepared with a plurality of testy yarns 53' each having a length of 60 cm and respectively folded by the pulleys 73 to be imparted predetermined tensions by a plurality of weights 76 suspended from the yarns 53'. The predetermined tension imparted to each of the yarns 53' is set at a level commensurate with that of the traveling yarn 53 treated by the yarn twist setting apparatus. The gadget 71 thus constructed and prepared as in the above is carried to the fluid reservoir 56 to have the yarn 53' together with the pulleys 73 and the plate members 74 immersed in the liquid 58 of the reservoir 56 maintained at a predetermined temperature for a predetermined time interval so that the yarn 53' is imparted the same condition as that imparted by the yarn twist imparting and heat-setting apparatus to reproduce a heat-setting process of the twisted yarn 53 to be performed by the gadget 71.

[0069] The above twist heat-set effect is appreciated by the following measurement method represented by a double torque measurement method after the torques of the two yarns subjected to the above heat-set treatment and not subjected to the above heat-set treatment are measured to compare the torque of the yarn not subjected to the heat-treatment and the residual torque of the yarn subjected to the heat-treatment. The double measurement method is shown in Fig. 5 as being initiated by the steps of preparing a test yarn 53' having a length of about 60 cm and having both end portions adhered to a fixing member 82 by an adhesion tape 83, and suspending a light weight 81 from the central portion of the yarn 53' to prevent the test yarn from being untwisted or varied in its twisted condition. The weight of the light weight 81 is set at 2 x 0.001 g/de (gram/denier). The torque of the twisted yarn 53' causes the suspended light weight 81 to be rotated because the folded yarn 53' is forced to be twisted under the influence of the light weight 81. The light weight 81 is rotated until the torque of the twisted yarn 53' is diminished to zero level to stop the light weight 81, and the yarn 53' is then carried under the condition that the folded yarn is not untwisted to a known yarn twist detecting machine (not shown in the drawings) where the folded yarn 53' starts to be untwisted until the folded yarn 53' is completely untwisted to have two straight and virtually parallel portions to count turns of twist (torque level) of the yarn 53'. In this way, the experiments are made for samples, the number of the samples n=10, to count the turns of twist of the yarn for respective samples, and the average value calculated on the resultant values of the yarns 53' is decided as a torque (T/50 cm). The test yarn 53' is clipped at its points spaced at a distance of 25 cm in the yarn twist detecting machine.

[0070] The experimental examples will hereinlater be described together with the comparative examples represented by the dry type of the heat-setting treatment.

<First Experimental Example and First Comparative Example>

[0071] Under the condition that the heat-set time for the yarn 53 was fixed while the heat-set temperature for the yarn 53 was varied, the yarn twist effect of the yarn 53 produced by a wet type of twist heat-setting process represented by the present experimental example was compared with the yarn twist effect of the yarn 53 produced by a comparative example represented by a dry type of twist heat-setting process, and the variation of the yarn twist effect of the yarn 53 was measured.

[0072] First Experimental Example: The test yarn 53 was represented by a yarn made of polyethylene terephthalate and 92de/36Fil with "Z" twist having turns per meter of 1472T/M. The torque of the yarn 53 not subjected to the heat-setting treatment was measured by the double torque measurement method at 80 - 88 (T/50 cm). The temperature of the liquid 58 in the fluid reservoir 56 was set at a predetermined value ranging between 70 - 100 °C. Under these conditions, the gadget 71 with the yarn 53 spanned thereon was immersed in the liquid 58 of the fluid reservoir 56 until the yarn 53 is raised to the predetermined temperature for the time interval of 15 sec (heat-set time). The yarn 53 was then taken out of the liquid 58 of the fluid reservoir 56 for measurement of its residual torque whose results are shown in Fig. 7.

[0073] First Comparative Example: As shown in Fig. 6, the yarn 53 was spanned on the gadget 53 in a similar manner to the first experimental example, and was then accommodated together with the gadget 71 in a heating housing 85 preliminarily maintained at a temperature ranging between 80 -200 °C. The yarn 53 was then left and heated in the heating housing 85 for a heat-set time of 15 seconds. The yarn 53 was then taken out from the heating housing 85 for measurement of its residual torque whose results are also shown in Fig. 7.

[0074] As will be seen from the graph shown in Fig. 7, the first experimental example and the first comparative example are recognized difference in their heat-set effects which becomes large toward the higher heat-set temperature of the yarn 53. For example, the residual torque of the yarn 53 to be set at 30T/50 cm needs the heat-set temperature of 100 °C in the first comparative example while needing the heat-set temperature of 75 °C (different at 25 °C) in the first experimental example. In order to set the twist of the yarn 53 at about 100% by heat-setting treatment and to set the residual torque 2T/50 cm, the temperature of about 200 °C is required in the comparative example and differs by the temperature of 100 °C from the present experimental example. The yarn 53 subjected to the heat-setting treatment of the comparative example has core and surface portions different in heat-set effect, resulting in the feeling of the yarn 53 inferior to the yarn produced by the steam box process. However, the yarn 53 subjected to the heat-setting treatment of the experimental example has core and surface portions not different in heat-set effect, resulting in the feeling of the yarn commensurate with that of the yarn 53 produced by the steam box process.

<Second, Third Experimental Example and Second Comparative Example>

[0075] The following conditions for the set temperatures (heat-set temperatures) of the fluid reservoir 56 and the heating housing 85, the immersing time of the yarn in the liquid 58 and the leaving time of the yarn in the heating housing (heat-set time) were tried to be varied for having the twist of the yarn 53 heat-set. The heat-set temperatures in the above were measured. The torque of the yarn 53 before the heat-set treatment of the yarn was 80 (T/50 cm).

Second Experimental Example

heat-set temperature: 50°C - 100°C
heat-set time: 15 sec

Third Experimental Example

heat-set temperature: 50°C - 100°C
heat-set time: 30 sec

Second Comparative Example

heat-set temperature: 60°C- 100°C
heat-set time: 15 sec

[0076] The measurement results on the residual torques of the yarns treated by the above Examples are shown in Fig. 8.

[0077] As will be seen from the graph shown in Fig. 8, the residual torque of the yarn 53 subjected to its twist heat-set treatment at the temperature of more than 60 °C by the second and third experimental examples was partly decreased from the torque 80T/50 cm (Z twist) before the yarn is subjected to its heat-set treatment. In contrast, the residual torque of the yarn 53 subjected to its twist heat-set treatment at the temperature of 50 °C for the heat-set time of 15 sec or 30 sec by the second and third experimental examples was not varied before and after the yarn is subjected to its heat-set treatment. Therefore, the heat-set effect of the yarn 53 treated under these conditions were not recognized before and after the yarn is subjected to its heat-set treatment.

[0078] The heat-set temperature of the liquid 58 for heat-setting the yarn 53 was perceived from the above experimental examples as being required to be more than 50 °C, preferably more than 60 °C. As it is considered to be more desirable for the heat-set effect of the yarn to raise the heat-set temperature at as a higher level as possible, the heat-set temperature may be considered to be more than 100 °C. The heat-set temperature is, however, preferably hot water at the temperature of less than 100 °C in consideration of the easiness in handling the liquid 58. The heat-set temperature of the yarn in the second comparative example is recognized as being required to be high similarly to the temperature of the yarn in the first comparative example previously mentioned.

[0079] The set temperatures (heat-set temperatures) of the fluid reservoir 56, and the immersing time of the yarn in the liquid 58 (heat-set time) were tried to be varied as in the following conditions for having the twist of the yarn 53 heat-set. The heat-set effect in relatively short time interval were measured. The torque of the yarn 53 before the heat-set treatment of the yarn was 80 - 88 (T/50 cm).

Fourth Experimental Example

heat-set temperature: 90 °C
heat-set time: 0.1 sec - 5 sec

Fifth Experimental Example

heat-set temperature: 92.5 °C
heat-set time: 0.5 sec - 5 sec

Sixth Experimental Example

heat-set temperature: 95 °C
heat-set time: 0.5 sec - 5 sec

Seventh Experimental Example

heat-set temperature: 100 °C
heat-set time: 0.5 sec - 5 sec

[0080] The measurement results on the residual torques of the yarns treated by the above Experimental Examples are shown in Fig. 8.

[0081] As will be seen from the graph shown in Fig. 9, there is perceived a large difference in heat-set effect of the yarn subjected to the heat-set treatment for the heat-set time of less than 2.5 sec at the heat-set temperature of more than 90 °C as exemplified in the fourth experimental example with the heat-set time of 5 sec and in the seventh experimental example with the heat-set time of 1 sec to secure the residual torque of the yarn 53 at 5T/50 cm. The following table indicates the residual torque of the yarn 53 corresponding to the heat-set time measured by the seventh experimental example.

heat-set time (sec)	residual torque (T/50cm)	residual torque (%)
5	5	6
2.5	5	6
1	5	6
0.5	12	14
0.2	18	21
0.1	22	26

[0082] Residual torque (%) = Residual Torque after Treatment / Residual Torque before Treatment

[0083] Here, the lower limit of the heat-set time will be examined as follows. From the previous table made by the seventh experimental example, it is recognized that the heat-set time should be 0.1 sec for the residual torque of 26 % (heat-set ratio 74 %) and that the heat-set time should be 1 sec or more for making the twist of the yarn heat-set at almost 100 %. As shown in Fig. 9, the twist of the yarn is uniformly heat-set as the heat-set time of the yarn 53 become long, thereby bringing even heat-set effect to the yarn 53. In this way, the twist of the yarn 53 can be heat-set at a predetermined heat-set ratio if the heat-set temperature and the heat-set time are selected in consideration of the denier of the yarn 53, the operational efficiency of the yarn 53 and others. When the yarn 53 was tried to be treated at the heat-set time of 100 °C and at a heat-set time of below 1 sec, it is recognized that there is expected slight heat-set effect for the treated yarn 53, however, there is large unevenness for the residual torques of the yarns, which results in failure in providing practical use under these conditions. It is thus to be appreciated that the heat-set time of the yarn 53 be above 0.1 sec.

<Eighth to Tenth Experimental Examples>

[0084] The set temperatures (heat-set temperatures) of the fluid reservoir 56, and the immersing time of the yarn in the fluid 58 (heat-set time) were tried to be varied as in the following conditions for having the twist of the yarn 53 heat-set. The heat-set effect in relatively long time interval were examined. The torque of the yarn 53 before the heat-set treatment of the yarn was 80 - 88 (T/50 cm).

Eighth Experimental Example

heat-set temperature: 70 °C
heat-set time: 0.1 sec - 15 sec

Ninth Experimental Example

heat-set temperature: 80 °C
heat-set time: 5 sec - 60 sec

Tenth Experimental Example

heat-set temperature: 90 °C
heat-set time: 5 sec - 90 sec

[0085] The measurement results on the residual torques of the yarns treated by the above Experimental Examples are shown in Fig. 10.

[0086] As will be seen from the graph shown in Fig. 10, the heat-set effect of the twisted yarn 53 can be recognized by the experimental results as becoming high in proportion to the high heat-set temperature while the residual torque of the yarn being gradually diminished as the heat-set time for the yarn becomes long.

[0087] Here, the upper limit of the heat-set time will be examined as follows.

[0088] The optimum value of the heat-set temperature in the previously described steam box process ranges from 60 °C to 80 °C. From this fact, it is recognized that when the yarn 53 is treated at the twist heat-set ratio of 85 % (residual torque 15 %) in the ninth experimental example with the heat-set temperature of 80 °C the heat-set time should be 30 sec in Fig. 10 since the torque of the yarn 53 before the heat-set treatment of the yarn should be varied from 80 - 88T/50cm to 13T/50cm. A new synthetic fiber, machine yarn and the like of 200de - 300de are considered to constitute a clothing yarn which has a volume approximately three times that of the yarn 53 (92de), viz., a diameter 1.7 times that of the yarn 53 (92de). In order to heat-set the above clothing yarn at the heat-set ratio of 85 % in the ninth experimental example, the heat-set time of the clothing yarn should be 90 sec which is tantamount to three times that of the yarn 53 treated in the ninth experimental example. The upper limit of the heat-set time is thus considered to practically be 90 sec in consideration of the operational efficiency of the above apparatus and the like.

<Eleventh Experimental Example>

[0089] Three kinds of yarns 53 respectively having twist number of 632T/M, 1472T/M and 1945T/M were prepared, and the set temperature (heat-set temperature) of the fluid reservoir 56 were unchanged. Under these conditions, the immersing times of the yarn 53 (heat-set time) immersed in the fluid 58 were varied as shown in the following list to have the twist of the yarn 53 heat-set and to examine the variation of the heat-set effect based on the twist number of the yarn 53. Incidentally, the torques of the yarns 53 not subjected to the heat-treatment of the yarn were indicated at 80 - 88 (T/50cm), 80 - 88 (T/50cm), and 112 - 127 (T/50cm),
   Heat Set Temperature: 80 °C
   Heat Set Time: 1 sec, 2.5 sec, 5 sec, 10 sec, 15 sec, 30 sec

[0090] The measurement results on the residual torques of the yarns treated by the above Examples are shown in Fig. 11.

[0091] The heat-set effect is shown in Fig. 11 by residual torques represented by the twist turns (T/50cm) of the yarns 53. The heat-set effects of the yarns 53 are estimated from Fig. 11 to differ on the twist turns of the yarns 53, however, the heat-set effects of the yarns 53 respectively having the twist numbers 1472T/M and 1945T/M are not recognized to drastically differ as shown by the relation between the heat-set time and the residual torque (%) in Fig. 12. This makes it possible to estimate that the twist turns of the yarn scarcely affect the heat-set effect of the yarn in the range of the yarn twist turns of 1500 -2000 T/M.

<Twelfth Experimental example>

[0092] 

[0093] The weight 76 suspended from the yarn 53 was replaced with another weight different in weight to keep the tensions of the yarn 53 at 25 gr. and 50 gr., and the set temperature (heat-set temperature) of the fluid reservoir 56 were unchanged. Under these conditions, the immersing times of the yarn 53 (heat-set time) immersed in the fluid 58 were varied as shown in the following list to have the twist of the yarn 53 heat-set and to examine the variation of the heat-set effect based on the tensions of the yarn 53. Incidentally, the torques of the yarns 53 not subjected to the heat-treatment of the yarn were indicated at 80 - 88 (T/50cm).
   Heat Set Temperature: 80 °C
   Heat Set Time: 5 - 30 sec

[0094] The measurement results on the residual torques of the yarns treated by the above Examples are shown in Fig. 13.

[0095] As will be seen in Fig. 13, the heat-set effect of the yarn 53 is improved if the yarn 53 is of tension having a relatively small value.

[0096] The previously mentioned examples have been stated with the heat-set temperatures of 90 - 100 °C which are relatively high to have the twist of the yarn 53 heat-set, thereby resulting in the heat-set time being set at 0.25 to 2.5 seconds, relatively short times. According to the present invention, however, the heat-set temperature may be set at a relatively low level of 60 °C, and the heat-set time may be prolonged depending upon the twist heat-set ratio of the yarn 53. Although the upper limit of the heat-set time is not necessarily limited, the heat-set time is preferably below 90 sec similar to the previous examples in consideration of the depth of the fluid reservoir 56 and the traveling speed of the yarn 53. More specifically, the heat-set temperature ranging from 60 °C to 100 °C and the heat-set time ranging from 0.1 sec to 90 sec should be predetermined according to the present invention for treatment of the twisted yarn 53 to bring the same effect as that of the above examples and to ensure the yarn 53 commensurate in feeling with that of the yarn twist-set at a predetermined heat-set ratio in the steam box process.

[0097] The foregoing examples have been explained with the yarn 53 immersed in the fluid 58, however, the yarn 53 may be forced into contact with the fluid 58 in place of being immersed in the fluid 58. For this end, there is proposed a water imparting apparatus 55 which is shown in Fig. 14 as being exemplified to comprise a fluid reservoir 90 accommodating therein a fluid heated at a temperature ranging from 60 °C to 100 °C, a first roller 91 having a peripheral surface partly immersed in the fluid 98, and a second roller 92 held in pressing contact with the first roller 91 at a position spaced apart from the fluid 98. The yarn 93 which is traveling at a predetermined speed from the snail guide 94 to the feed roller 95 after being twisted by the twisting spindle 51 can be forced into contact with the fluid 98 on the periphery of the first roller 91 for a predetermined time interval. The time interval may be varied in response to the rotation speed of the first roller 91 in the range of 0.1 to 90 seconds. The yarn 93 is imparted with a roughly even amount of fluid by the first roller 91 and the second roller 92 before the residual amount of fluid on the peripheral surface of the yarn is removed by the compressed air unit 60 and then directly or indirectly heated by the heating unit 61. The treatment performed by the water imparting apparatus previously mentioned can ensure advantageous effects same as those of the foregoing examples by making the core and surface portions of the yarn 93 evenly and rapidly heat-set in their twists. The reference numerals 90a and 90b respectively represent through bores formed in the fluid reservoir 90 to allow the yarn 93 to pass therethrough.

[0098] The means for imparting the fluid to the twisted yarn may be constituted by other embodiments of atomizing fluid to the yarn, or otherwise blowing fluid to the yarn through bores formed in the yarn guide to have the yarn imparted with the fluid while being passed on the yarn guide to be held in contact with the fluid. These embodiments can also bring same effects as those of the previously mentioned examples.

[0099] By the reason that the above heat-setting process according to the invention comprising the step of having the twisted yarn held in contact with a liquidized fluid heated at a temperature of 60 to 100 °C for a time interval of 0.1 to 90 seconds to heat-set the twist of the yarn, the yarn produced by the process as set forth in the above is not of the feeling of the yarn inferior to the yarn produced by the steam box process and can continuously be produced with the core and surface portions being evenly heat-set in addition to the advantages of the process. Further, the process can provide at a low cost a full package formed by the yarn wound on the bobbin without any rewinding operation needed in the conventional process.

[0100] While there have been described about the preferred embodiments of the present invention in the foregoing description, various modifications and adaptations thereof may be made within the spirit of the present invention as set forth in the following claims.

Claims

1. A process of having a yarn (13; 53) twisted while said yarn (13; 53) is travelling along a yarn travel path and then heat-treating said twisted yarn (13; 53) to have the twist of said yarn (13; 53) heat-set, comprising the steps of:
   having said twisted yarn (13; 53) held in contact with a liquidized fluid (18; 58) of heat conductivity higher than that of air and imparting said liquidized fluid (18; 58) to said twisted yarn (13; 53), and
   heating said twisted yarn (13; 53) and said liquidized fluid (18; 58) imparted to said twisted yarn (13; 53) to a degree that the twist of said yarn (13; 53) is heat-set.

2. A process of having a yarn (13; 53) twisted while said yarn (13; 53) is travelling along a yarn travel path and then heat-treating said twisted yarn (13; 53) to have the twist of said yarn (13; 53) heat-set, comprising the steps of:
   heating a liquidized fluid (18; 58) of heat conductivity higher than that of air to a degree that said liquidized fluid (18; 58) is hot enough to heat-set the twist of said yarn (13; 53), and
   having said twisted yarn (13; 53) held in contact with said heated liquidized fluid (18; 58) to impart said heated liquidized fluid (18; 58) to said yarn (13; 53) and heat-setting the twist of said yarn (13; 53) by said heated liquidized fluid (18; 58).

3. A process of having a yarn (53) made mainly of polyethylene terephthalate twisted while said yarn (53) is travelling along a yarn travel path and then heat-treating said yarn (53) to have the twist of said yarn (53) heat-set, comprising the steps of:
   having said twisted yarn (53) held in contact with a liquidized fluid (58) of heat conductivity higher than that of air for 0.1 to 90 seconds and imparting said liquidized fluid (58) to said twisted yarn (53), and
   heating said twisted yarn (53) and said liquidized fluid (58) imparted to said twisted yarn (53) to a temperature of 60 to 100 °C to heat-set the twist of said yarn (53).

4. A process of having a yarn (53) made mainly of polyethylene terephthalate twisted while said yarn (53) is travelling along a yarn travel path and then heat-treating said yarn (53) to have the twist of said yarn (53) heat-set, comprising the steps of:
   heating a liquidized fluid (58) of heat conductivity higher than that of air to a temperature of 60 to 100°C, and
   having said twisted yarn (53) held in contact with said heated liquidized fluid (58) for 0.1 to 90 seconds to impart said heated liquidized fluid (58) to said yarn (53) and heat-setting the twist of said yarn (53) by said heated liquidized fluid (58).

5. A process as set forth in any preceding Claim, in which said twisted yarn (13; 53) is held in contact with said liquidized fluid (18; 58) by passing said twisted yarn (13; 53) through said liquidized fluid (18; 58).

6. A process as set forth in any one of Claims 1 to 4, in which said twisted yarn (13; 53) is held in contact with said liquidized fluid (18; 58) by coating said liquidized fluid (18; 58) onto said twisted yarn.

7. A process as set forth in any preceding Claim, further comprising the step of removing said liquidized fluid (18; 58) from said twisted yarn (13; 53) on said yarn travel path after the heat-treatment of said twisted yarn (13; 53).

8. A process as set forth in Claim 5, or in Claim 7 when dependent upon Claim 5, in which said twisted yarn (53) is held in contact with said liquidized fluid (58) by passing said twisted yarn (53) through said liquidized fluid (58) for 0.1 to 90 seconds.

9. A process as set forth in any preceding Claim, in which said yarn (13; 53) is twisted at a twist number not less than 600 turns per meter.

10. An apparatus for having a yarn (13; 53) twisted while said yarn (13; 53) is travelling along a yarn travel path and heat-treating said twisted yarn (13; 53) to have the twist of said treated yarn (13; 53) heat-set, comprising:
yarn transferring means (15, 19 and 23; 31 and 32; 55, 59 and 63; 91 and 92) for transferring said yarn (13; 53) along said yarn travel path,
yarn twisting means (11) for twisting said yarn (13; 53) on said yarn travel path,
fluid imparting means (2; 30; 42; 90) for imparting a liquidized fluid (18; 58) to said twisted yarn (13; 53) on said yarn travel path by holding said twisted yarn (13; 53) in contact with said liquidized fluid (18; 58) of heat conductivity higher than air, and
yarn heating means (2 or 21; 30; 42 or 61; 90) for heating said twisted yarn (13; 53) on said yarn travel path and said liquidized fluid (18; 58) imparted to said twisted yarn (13; 53) to a degree that the twist of said yarn (13; 53) is heat-set.

11. An apparatus as set forth in Claim 10, in which said fluid imparting means (2; 90) comprises a fluid reservoir (16; 56) for reserving said liquidized fluid (18; 58), and a yarn treating roller (17; 57) immersed in said liquidized fluid (18; 58) of said fluid reservoir (16; 56) to be held in contact with said twisted yarn (13;53) passing through said liquidized fluid (18;58), said yarn treating roller (17; 57) being vertically moveable to have the immersed length of said twisted yarn (13; 53) varied in response to the position of said yarn treating roller (17; 57) in said liquidized fluid (18;58).

12. An apparatus as set forth in Claim 10 in which said fluid imparting means (30; 90) comprises a fluid reservoir (36; 96) for a reserving said liquidized fluid (18; 58), and a yarn treating roller (31; 91) held in contact with said twisted yarn (13; 53) and partially immersed in said liquidized fluid (18; 58) to impart said liquidized fluid (18; 58) to said twisted yarn (13; 53) on the periphery of said yarn treating roller (31; 91) exposed to the air.

13. An apparatus as set forth in either one of Claims 11 or 12, in which said fluid imparting means (30; 90) further comprises a contact roller (32; 92) held in frictional contact with and rotatable together with said yarn treating roller (31; 91) to have said twisted yarn (13; 53) pass between said contact roller (32; 92) and said yarn treating roller (31; 91).

14. An Apparatus as set forth in Claim 11, or Claim 13 when dependent upon Claim 11, in which said fluid imparting means (2;42) is operated to have said twisted yarn (13; 53) immersed in said liquidized fluid (18; 58) at an immersed time varied in response to the position of said yarn treating roller (17; 57) in the range of 0.1 to 90 seconds.

15. An apparatus as set forth in Claim 12, or Claim 13 when dependent upon Claim 12, in which said fluid imparting means (30; 90) is operated to have said twisted yarn (13; 53) held in contact with said liquidized fluid (18; 58) at a contact time varied in response to the rotation speed of said yarn treating roller (31; 91) within the range of 0.1 to 90 seconds.

Drawing