A fluted roller for the draft apparatus of a spinning machine and a method of producing same

Abstract

 The present invention relates to a fluted or grooved roller (2) suitable for use in the draft apparatus of a spinning machine, and a method for producing the same. The surface of the roller (2) with grooves (1) is formed from a steel material and then quench hardened. Consequently, the surface is finished by a shot peening process.

Description

[0001] This invention relates to a fluted or grooved roller for use in the draft apparatus of a spinning machine and a method of producing same.

[0002] In the draft apparatus of a spinning machine for stretching fiber bundles such as slivers, rovings, slubbings or the like, there are employed a pair of top and bottom rollers for securely nipping or grasping the fibers therebetween without causing injury. For this purpose, the bottom roller is constituted by a fluted or grooved roller formed with a number of grooves 1 generally extending in the axial direction of the roller at each of spaced locations where the fiber bundles are caused to pass through between the paired rollers, as shown in Fig. 1 of the accompanying drawing, in which the fluted roller is generally designated by a reference numeral 2.

[0003] With reference to such a fluted roller, it has been known that factors, such as the surface condition of the fluted roller 2, and the geometrical configuration of corner edge portions 3a of protrusions 3 shown in Fig. 2, are very important factors in the fiber wrapping around the roller as well as in the breakage of the fiber bundles. Assuming that the fluted roller 2 is used with the corner edge portions 3a remaining sharp without being rounded off, there may arise a danger that the fiber bundle or the cot of the top roller could be damaged. On the other hand, a roller having the corner portions 3a rounded off with an extremely great curvature will necessarily involve some degradation in the fiber nipping capability. Also, it has been known that a fluted roller with a finished surface having many fine and sharp projections (i.e. having remarkable rough surface) promotes the tendency of fiber wrapping and deposition or adhesion of flies to adversely affect the spinned product.

[0004] In view of the above known facts, it is understood that a fluted roller should satisfy the following requirements:

(1) It should be capable of applying a uniform nipping force to the fibers without giving rise to injury of the top roller, apron, etc.;

(2) The fluted surface (the top surface of each protrusion 3) of the roller should be so smooth that wrapping of the roller by fibers as well as deposition or adhesion of the flies and/or dust can be avoided while allowing the fibers to easily drape on the fluted surface; and

(3) The roller should exhibit excellent corrosion/abrasion resistance.

[0005] Heretofore, in order to perform the required surface finishing of the fluted roller, a method has been generally adopted, in which a mechanical polishing process such as buffing or the like is carried out in succession to the formation of the grooves (fluting) and the subsequent quench hardening. Alternatively, a method in which an electrolytic polishing is performed after the fluting and hardening by a high-frequency induction heating process (reference may be made to Japanese Patent Publication No. 4743/1967) has been utilized.

[0006] However, with the surface finishing process relying only on mechanical polishing such as buffing, many fine streaks each exhibiting directivity will be formed to remain in the polished surface of the roller, while the roundness imparted to the corner portions of the protrusions defining the grooves come to differ significantly from one another, as a result of which the fluted roller becomes susceptible to the fiber wrapping, fly or dust deposition and the application of fiber nipping pressure also becomes disproportional. Further, such a roller lacks adequate corrosion resistance. On the other hand, the electrolytic polishing method can certainly assure an improvement over the above-mentioned method in respect to the low susceptibility of the finished roller to the occurrence of fiber wrapping and deposition of flies and dust by virtue of the high degree of smoothness of the polished roller surface. Additionally, the corrosion resistance of a roller having the surface finished by electrolytic polishing can be enhanced to a certain extent as well. However, the electrolytic polishing method is disadvantageous in that variations in the state of the finished surface more occur in comparison to the mechanical polishing method, thus giving rise to problems.

[0007] Therefore, it is an object of the present invention to provide a fluted roller for the draft apparatus of a spinning machine and a method for producing same, which roller has a surface finished uniformly and which can exhibit a reduced susceptibility to the wrapping of fibers, adhesion or deposition of flies and dust, can achieve a uniform and positive fiber nipping or gripping pressure, and which is excellent in respect to corrosion and abrasion resistance.

[0008] For achieving the above and other objects of the present invention which will become more apparent as description proceeds, there is provided according to a general aspect of the present invention a method of producing a fluted roller constituting the draft apparatus of a spinning machine, the roller being formed from a steel material and then hardenedg, characterized in that the fluted roller is processed by shot peening after being hardened.

[0009] The present invention also provides a fluted roller constituting the draft apparatus of a spinning machine, the fluted roller being formed from a steel material and then hardened, characterized in that the fluted roller has a surface finished by shot peening.

[0010] In a preferred embodiment of the present invention, the shot employed in the shot peening is formed of a vitreous (glass) material. The shot may be formed of a material having a hardness higher than that of the steel material of the roller and a greater ionization coefficient than that of iron.

[0011] According to another aspect of the present invention, the fluted roller formed from a steel material and then hardened has a surface finished by a first shot peening process carried out by using shot of a material having a hardness higher than that of the steel material and a second shot peening carried out in succession to the first peening by using shot of a material exhibiting a greater ionization coefficient than that of iron.

[0012] More specifically, the surface of a fluted roller made from a steel material and quench hardened is finished by a shot peening process for smoothing the surface of the fluted roller. Although the invention is not limited to any apparatusicular hardening process, a high-frequency induction hardening method is preferred. When subjected to the shot peening, the surface of a workpiece to be processed is generally worked by the shot blasted or projected from a blast finishing machine onto the surface of the workpiece. In this connection, it should be noted that the surface of the workpiece is not ground but beaten by the shot. As a consequence, not only are burrs on the surface of the workpiece broken away, but also fine and radical roughness on the surface are smoothed, thus making the occurrence of the fiber wrapping phenomenon as well as deposition of the flies and dust on the surface of the fluted roller difficult. Further, with the shot peening process, the corner portions of the groove defining protrusions can be suitably rounded off, which is very advantageous in suppressing variations in the fiber nipping pressure as well as in protecting the apron and the top roller against injuries. The curvature for the rounding can be selectively determined depending of the size, hardness and the beating speed of the shot as employed among others.

[0013] Moreover, by repeating the beating of the roller surface with the shot, texture of the surface layer of the fluted roller is micro-structured, while at the same time the texture is changed to undergo surface-hardening. This means that the abrasion resistance of the fluted roller is improved correspondingly. Further, another advantage brought about by the shot peening can be seen in that compressive stress remains at the surface of the fluted roller to thereby increase fatigue strength.

[0014] When shot of a vitreous material such as, for example, glass beads are used, the whole surface of the fluted roller is eventually covered by a thin layer of a glass material, as the result of which there is provided a fluted roller which is less susceptible to corrosion or rust even when the fluted roller is used in highly humid environments. The resistance of the roller to rust (i.e. corrosion resistance) is greatly improved when compared with rollers finished by electrolytic polishing. Instead of carrying out a single-step shot peening by using only glass beads as shot, a two-step shot peening process may preferably be employed, according to which the processing for removing the burrs and/or roughness is first performed by using shot of abrasive grains or shot of iron or stainless steel material, to then be followed by a second step in which the shot peening is carried out using glass beads. In that case, the time required for the shot peening as a whole can be shortened as compared with shot peening effected by using only the glass beads, whereby the manufacturing cost can be reduced correspondingly. In particular, when burrs removal is performed by using shot of a stainless steel material, the effect of the surface hardening due to the textural change of the surface layer of the roller becomes remarkable. Of course, it goes without saying that a mixture of glass beads and beads of one or more of abrasive grains, iron and stainless steel materials may equally be used. Although the present invention is not limited to any particular type of blasting machine, an air-acceleration type blasting machine is preferred. The surface finished by the shot peening process is more uniform than that realized by electrolytic polishing.

[0015] Primarily, for the purposes of imparting the fluted roller with the property to resist corrosion due to humidity, it is possible to carry out shot peening by using shot made of a material having a greater ionization coefficient than iron such as, for example, aluminum, zinc or the like, in addition to shot peening effected by using shot having a hardness higher than that of the roller material. (The first mentioned shot peening differs from normal shot peening because the hardness of aluminum, zinc or the like is far lower than that of the fluted roller to be processed.) When shot of zinc or aluminum is used as the beating means, zinc or aluminum tends to be deposited on the roller surface. In this connection, it must be noted that for corrosion of iron to take place, iron must first be ionized and for ionization, it is necessary that a great number of water molecules be present. However, a water layer formed over the surface of the fluted roller through deposition of water molecules from the atmosphere may provide sufficient water molecules for ionization.

[0016] By using glass beads as the peening shot, the whole surface of the fluted roller is covered with a thin glass film, making it difficult for water molecules to be present on the roller surface in an amount large enough to cause rust to be generated. In contrast, when zinc or the like is employed as the shot material, zinc or the like is not necessarily deposited in the form of a film covering the whole roller surface but may only be deposited locally. This means that a water deposition layer capable of providing water molecules in a number large enough to ionize iron may exist on the roller surface. However, since the standard electrode potential of zinc or the like is more negative than that of iron, zinc or the like is ionized in precedence to the ionization of iron. Accordingly, even if an amount of water molecules sufficient to ionize metals is present on the roller surface, zinc or the like deposited on the fluted roller is ionized prior to ion, whereby the fluted roller can be protected against generation of rust. It should be mentioned that the fluted roller having the surface processed by shot peening with glass beads may additionally be processed by using shot of zinc, aluminium or the like.

[0017] The above and other objects, novel features and advantages of the present invention will be more apparent from the following description of an exemplary embodiment of the invention. Parenthetically, the accompanying drawing shows a structure of a fluted roller an improvement of which the present invention is concerned with, in which:

Fig. 1 is a fragmentary elevational view of a fluted roller; and

Fig. 2 shows a cross-section of the same with a portion being broken away.

[0018] The mechanical structure of the fluted roller itself is known heretofore and apparent from the description made hereinbefore. Accordingly, repeated description will be unnecessary. The following description is directed to an exemplary embodiment of the invention.

Exemplary Embodiment

[0019] A fluted roller made of a carbon steel material was hardened by using a high-frequency induction heating apparatus and subsequently subjected to a shot peening process by using No. 300 size glass beads blasted under an air pressure of 5.5 kgf/cm² from an air blasting machine. For the surface of the fluted roller thus finished, distribution of elements in a depthwise direction was measured through an electron spectroscopy. As a result, silicon, calcium and other constituents of the glass beads were detected over the whole roller surface to a depth of about 100 angstroms. Thus, a glass layer having a thickness of about 100 angstroms was formed over the whole surface of the fluted roller.

[0020] The abovementioned fluted roller was held within an isothermal/humidistatic bath set at a temperature of 40°C and a humidity of 95 % together with a fluted roller electrolytically polished and serving as a comparative control sample, whereon a corrosion resistance test was carried out by observing the state of generation of rust on both of the fluted rollers. It was found that the state of rust generated on the fluted roller according to the invention after a time lapse of 120 hours was equivalent to the state of rust prevailing on the control sample after a lapse of 24 hours.

[0021] Additionally, time taken for auto-reduction of the surface coating was measured for both fluted rollers. It was found that auto reduction of the fluted roller processed on the basis of the present invention took about twice as long as that for the electrolytically polished roller, which fact substantiates that the fluted roller according to the present invention exhibits higher resistance to corrosion than the electrolytically polished roller.

[0022] It should be understood that the invention can equally be applied to a knurled bottom roller for the draft apparatus of a spinning machine.

[0023] Comparison of the fluted roller shot by glass beads alone according to the invention with those finished through the conventional buffing and electrolytic polishing, respectively, are summarised in the following table.

[0024] As appreciated from the foregoing, the present invention can provide a fluted roller for the draft part of a spinning machine, which can resist fiber wrapping and deposition of flies and dust with positive and uniform fiber nipping pressure comparable to or superior to fluted rollers finished through conventional electrolytic polishing processes and which is vastly superior to the latter in respect to abrasion resistance and fatigue strength, resulting in greatly extended effective life. Further, the quality of the finished surface of the fluted roller according to the present invention is featured by high uniformity.

[0025] The many features and advantages of the invention are apparent from the detailed specification and thus it is intended by the appended claims to cover all such features and advantages of the invention which fall within the true spirit and scope thereof. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.

Claims

1. A method of producing a fluted roller for use in the draft apparatus of a spinning machine, the roller being formed from a steel material and then hardened, characterized in that the fluted roller is surface finished by shot in a shot peening process after being hardened.

2. A method according to claim 1, characterized in that the shot is formed of a vitreous material.

3. A method according to claim 1, characterized in that the shot comprises glass beads, and beads formed of at least one material selected from abrasive grains, iron, and stainless steel.

4. A method according to claim 1, characterized in that the shot is formed of a material having a hardness higher than that of the steel material and an ionization coefficient greater than that of iron.

5. A method according to claim 1, characterized in that the shot peening process comprises a first step of shooting glass beads, and a second subsequent step of shooting beads formed of at least one material selected from abrasive grains, iron, stainless steel, zinc, and aluminum.

6. A method according to claim 1, characterized in that the shot peening process comprises a first step of shooting beads formed of a material having a hardness higher than that of the steel material, and a second subsequent step of shooting beads formed of a material having an ionization coefficient greater than that of iron.

7. A hardened fluted roller for use in the draft apparatus of a spinning machine, the roller being formed from a steel material, characterized in that the roller has a surface layer formed therearound by shot peening after being hardened.

8. A roller according to claim 7, characterized in that the surface layer is a glass layer having a thickness of about 100 angstroms.

Drawing