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(11) | EP 0 140 526 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Intermining mulifilament yarns |
| (57) A method of intermingling one or more multifilament yarns comprises feeding said
yarn or yarns along a yarn channel having a uniform V-shaped cross-section throughout
its length and admitting at least one fluid stream to said channel in a direction
transversely of the channel and at a velocity such that air turbulence in the channel
causes the yarn filaments to intermingle. A device for intermingling multifilament yarns, comprises a yarn channel of V-shaped cross-section having two convergent channel sides bridged by a third side having a yarn entry slot positioned adjacent a fluid channel for admitting a high velocity fluid stream to said channel in a direction transversely of the axis of yarn travelling in said channel in use so as to intermingle the yarn filaments and prevent escape of the yarn from the channel. |
[0002] It is well known that multifilament yarns, as extruded, possess undesirable aesthetics and handle, and require further processing to render them pleasing to the eventual consumer. Undoubtedly the false twist texturing technique has become accepted worldwide as the preferred method. Increasing machine throughput speeds, quality demands, and need for greater efficiency relevant to operational costs have highlighted inadequacies in the structure of the false twisted yarn and product package as produced on the most modern texturing machines. Recently, a method has been developed for intermingling or interlacing the yarn filaments on such false twist machines using a stream of fluid, e.g. air, directed transversely of the yarn whilst it is travelling through a guide. Turbulent air flow in the guide is thought to cause the filaments to separate and twist around each other, the twist being propagated upstream and downstream of the yarn to form regions of high coherence known as nips or nodes separated by regions of low coherence in which the yarn filaments remain substantially parallel. Use of such devices has been shown to offer methods of alleviating the above problems although presently there is no commercially available device that totally fullfills these requirements.
[0003] Some information about the intermingling process is contained in U.S. Patent No. 2 985 995 to du Pont of 1961 and an article in Chemiefasern Textilindustrie, March 1981, entitled "Mechanismus der Verwirbelung von Filamentgarmen" (Mechanisms of the intermingling of filament yarns) by Weinsd8rfer. Both publications describe yarn intermingling devices or jets comprising essentially a yarn passageway in combination with one or more air ducts for directing a stream of high velocity air at the yarn axis. Weinsd8rfer tested nine parameters with regard to their influenoe on interlacing density : pressure of the air, yarn tension, yarn speed, diameter of the air channel, diameter of the yarn channel, angle between yarn and air channel, length of the yarn channel, cross-section shape of the yarn channel, and application of several air channels. He showed that the shape of the yarn channel cross-section was of great importance for the effectiveness of the jet with a jet having a semi-circular shaped yarn channel cross-section being most efficient at low air pressure thus reducing air consumption. As a result of these and other studies it is now generally accepted in the art that the optimum yarn-channel cross-section for intermingling is semi-circular. Currently arailable commercial devices use either circular or semi-circular cross-section yarn channels.
[0005] According to a first aspect of the present invention there is provided a method of intermingling one or more multifilament yarns, comprising feeding said yarn or yarns along a yarn channel having a uniform V-shaped cross-section throughout its length and admitting at least one fluid stream to said channel in a direction transversely of the channel and at a velocity such that-air turbulence in the channel causes the yarn filaments to intermingle.
[0006] According to a second aspect of the present invention there is provided a device for intermingling multifilament yarns, comprising a yarn channel of V-shaped cross-section having-two convergent channel sides bridged by a third side having a yarn entry slot positioned adjacent a fluid channel for admitting a high velocity fluid stream to said channel in a direction transversely of the axis of yarn travelling in said channel in use so as to intermingle the yarn filaments and prevent escape of the yarn from the channel.
[0007] The invention will now be further described, by way of example only , with reference to the accompanying drawings, in which :-
Fig. 1 is a plan view of one embodiment of intermingling device in accordance with the invention;
Fig. 2 is a corresponding side elevation;
Fig. 3 is an end view;
Fig. 4 is a plan view of a cover of the device;
Fig. 5 is a side view of the cover;
Fig. 6 is a side elevation of a slightly different embodiment from the one shown in Fig. 2 with yarn guides mounted thereon;
Fig. 7 is an end view of one of the yarn guides of Fig. 6,
Figs. 8 and 9 are corresponding plan and side views of the yarn guide of Fig. 7;
Fig. 10 is a plan view of a second embodiment of intermingling device in accordance with the invention;
Fig. 11 is a corresponding end elevation of the device shown in Fig. 10, and
Fig. 12 is an end elevation to an enlarged scale of part of the device shown in Figs. 10 and 11.
[0008] Referring now to the drawings, an intermingling device comprises a rectangular block 1 with side flanges 2 and 3 made in one piece of ferrous material. The flat upper surface 4 of the block 1 is formed with a central V-section yarn channel 5 extending transversely thereof. Midway along the yarn channel 5 is an air inlet 6 disposed in the floor of the channel 5 in the angle between the downwardly convergent sides thereof. The air inlet 6 is the outlet end of a bore in the block 1 having a narrow section 7 and an enlarged section 8 adapted to be connected to a source of air under pressure. It will be noted that the narrow bore section 7 is at right angles to yarn channel 5 in both the plane extending lengthwise of the channel 5 (Fig. 2) and in the plane extending transversely of the channel 5 (Fig. 3).
[0009] The upper surface 4 of the block 1 has dowel holes 9, 10 for respective dowel pins (not shown) for locating a cover 11 having a lower surface 12, which is congruent with said surface 4 and has corresponding dowel holes 13, 14. The cover 11 may be made of magnetic material in order that it may be held firmly on the block 1 while nevertheless being easily removed and replaced to facilitate yarn thread-up.
[0010] The flanges 2, 3 have respective bores 15, 16 which are in line with the yarn channel 5 as seen in the plan view of Fig. 1. The bores 15, 16 have respective side openings 17, 18 which are threaded to receive set screws (now shown) for fixing the position of guide posts 19, 20 received in the bores 15, 16 (Fig. 6). Each guide post 19, 20 has a forked upper end which receives a yarn guide element 21, 22 made of ceramic material. As shown in Figs. 7 to 9 each yarn guide element 21, 22 is of generally rectangular shape with a recess in its upper edge comprising a lead-in 23 and a guide slot 24 in which the yarn runs in use. The guide posts 19, 20 are so positioned that the guide slots 24 of the yarn guide elements 21, 22 cause the yarn (Y in Fig. 6) to run in a straight line centrally of the channel 5, i.e. without contacting the sides thereof or the surface 12 of the cover 11 and substantially equidistant from said sides and surface, when no air is entering the channel 5 through the inlet 6.
[0011] The yarn channel 5 is of uniform V-shaped cross-section throughout its length, i.e. its profile comprises downwardly convergent, substantially planar side walls and does not vary from one end of the channel to the other. In the illustrated embodiment, the sides of the channel 5 are mutually inclined at an angle of 60° but, although this is the preferred angle, other angles of between 30° and 1200 are also within the scope of the invention although at the extremes of this range it may be necessary to expend undesirably large volumes of air to achieve the intermingling effect.
[0012] Tests were carried out to compare the performance of jets of the invention having different induded angles and the results are summarized in Table I. Surprisingly, the best results were obtained with an included angle of 60° and this jet was then found to perform better than a commercially available jet - see Table II. For testing each jet was installed after texturising and before wind-up of a Scragg FT machine. Yarn was processed to commercially acceptable process specification at 600mm. The feed yarn was 120 denier 34 filaments Du Pont Polyethylene Terephthalate and the draw ratio was 1.67:1. The yarns were tested using an automatic yarn entanglement tester type R2040 manufactured by Rothchild Messinstrumente A.G. of Zurich. A minimum of 25 measurements were performed on each yarn.
[0013] It will be appreciated that other modifications may be made without departing from the scope of the invention. For example, while the air jet or stream issuing from the air inlet 6 must be directed transversely of the yarn axis, i.e. the line Y taken by the yarn in Fig. 6, it is possible to angle the air stream in the direction of travel of the yarn by inclining the air passage 7 slightly out of the perpendicular position shown in Fig. 2.
[0014] The second embodiment of intermingling device comprises a self-threading yarn guide block 25 extending between yarn guides 26, 27 (Figs. 10 and 11). As best seen in the end elevation of Fig. 12, the block 25 has a central V-section yarn channel 28 extending therethrough. The yarn channel 28 is of uniform V-shaped cross-section throughout its length and the angle subtended by its downwardly converging sides is 60°. A lateral air inlet 29 enters the yarn channel 28 midway therealong at its upper left-hand edge as viewed in Fig. 12. The yarn channel 28 is connected by a constricted passage 30 to a V-section groove 31 in the upper surface of the block 25 serving as a lead-in for the yarn travelling between the guides 26, 27. The air inlet 29 is connected to a source of compressed air by an air channel 32 (Fig. 10) and a coupling (Fig. 11).
[0015] In use of the second embodiment the yarn to be intermingled is laid in the yarn guides 26, 27 so as to rest in the lead-in groove 31 of the block 25. When the air is turned on a suction effect is created in the passage 30 so as to assist entry of the yarn into the yarn channel 28. Air turbulence positions the yarn centrally in the channel 28 and the incoming air prevents the yarn from re-entering the passage 30 and accidentally escaping from the channel 28.
[0016] The above description has been concerned with processingbf a single yarn having multiple continuous filaments of extruded synthetic material. It will be appreciated that the invention is not so restricted. Thus, the yarn may be made of staple (discontinuous) fibre of material or synthetic material and the term "filament" is used in the claims to include both continuous and discontinuous filaments or fibres. Also, two or more yarns may be provided simultaneously so as to commingle the filaments thereof and produce a composite yarn.
1. A method of intermingling one or more multifilament yarns, comprising feeding said
yarn or yarns along a yarn channel having a uniform V-shaped cross-section throughout
its length and admitting at least one fluid stream to said channel in a direction
transversely of the channel and at a velocity such that air turbulence in the channel
causes the yarn filaments to intermingle.
2. A method as claimed in claim 1, wherein the outlet of the fluid channel is in the
floor of the yarn channel between the divergent sides thereof.
3. A method as claimed in claim 1 or 2, wherein the sides of the yarn channel are
inclined at an angle of between 30° and 120°.
4. A method as claimed in claim 3, wherein said angle is 600.
5. A method as claimed in anyone of-the preceding claims, wherein the yarn channel
is closed by a cover which is held in position by a magnetic force so as to be readily
removable for thread-up of the yarn.
6. A method as claimed in any one of the preceding claims, wherein yarn guides are
so positioned at or adjacent the ends of the yarn channel as to define a line of travel
of the yarn or yarns centrally along the channel with clearance from the sides thereof.
7. A device for intermingling multifilament yarns, comprising a yarn channel of V-shaped
cross-section having two convergent channel sides bridged by a third side having a
yarn entry slot positioned adjacent a fluid channel for admitting a high velocity
fluid stream to said channel in a direction transversely of the axis of yarn travelling
in said channel in use so as to intermingle the yarn filaments and prevent escape
of the yarn from the channel.
8. A device as claimed in claim 7, wherein the yarn channel is so shaped adjacent
the yarn entry slot as to cause a suction effect in said slot thereby facilitating
threading of the yarn into the channel.
9. A method of intermingling one or more multifilament yarns, substantially as herein
described with reference to the accompanying drawings.
10. A device for intermingling multifilament yarns, substantially as herein described
with reference to the accompanying drawings.