Tool for textiles and production method for same

Abstract

The tool (10) for textiles according to the invention consists of chromium steel, into which carbon has been embedded in locally varying amounts during a carbonizing process. Thermal treatment achieves a formation of martensite with the maximum achievable hardness, in particular in those zones in which larger carbon fractions have been introduced. A tool for textiles with zones of differing hardnesses can thus be produced without having to subject the individual zones with differing hardnesses to different process conditions during the production process. The hardness is controlled on the basis of the degree of deformation of the tool for textiles.

Claims

1. A tool (10) having a size within a range of thickness of needles for textiles, the tool comprising: a base body including a chromium steel and portions (14, 15) whose material displays differing degrees of deformation, said base body having a chromium content of 11% to 30%, an aluminum content of less than 0.3 percent by weight, a copper content of less than 0.4 percent by weight, and a total carbon content of more than 0.8% in at least one surface zone; wherein the base body consists essentially of a carburized chromium steel; wherein the base body has an initial carbon content of not more than 0.7%; wherein less than 20% of individual carbide crystals at a surface of the tool are connected by fusible links.

2. The tool for textiles as in claim 1 wherein the base body consists essentially of a chromium steel having a nickel content of not more than 12%.

3. The tool for textiles as in claim 1, wherein the base body contains chromium carbide.

4. The tool for textiles as in claim 1, wherein the base body hasin zones close to the tool's surfacea higher carbon content than in zones remote from the tool's surface.

5. The tool for textiles as in claim 1, wherein the base body includes full-hardness martensite.

6. The tool for textiles as in claim 1, wherein the base body is elongated and has, along its length, portions having different degrees of deformation and/or different surface/volume ratios.

7. The tool for textiles as in claim 6, wherein the base body has, in the zones displaying greater degrees of deformation and or greater surface/volume ratios, a greater hardness than in zones displaying lower degrees of deformation and/or lower surface/volume ratios.

8. The tool for textiles as in claim 1, wherein the base body is less deeply hardened in portions displaying lower degrees of deformation than in portions displaying greater degrees of deformation.

9. The tool for textiles as in claim 1, wherein the base body consists essentially of a carburized chromium steel having an initial carbon content of not more than 0.5%.

10. The tool for textiles as in claim 9, wherein the base body consists essentially of a carburized chromium steel having an initial carbon content of not more than 0.3%.

11. A method for providing tools (10) having a size within a range of thickness of needles for textiles, the method comprising: deforming various portions of a tool blank of a chromium steel with a base body having a chromium content of at least 11%, an aluminum content of below 0.3 percent by weight, a copper content of below 0.4 percent by weight, and a total carbon content of more than 0.8% in at least one surface zone, wherein the base body consists essentially of a carburized chromium steel, wherein the base body has an initial carbon content of not more than 0.7%, and wherein less than 20% of individual carbide crystals at a surface of the tool are connected by fusible links, with differing degrees of deformation for production of at least one working portion (14) and one shank portion (15), carburizing the tool blank under chromium carbide formation, applying a hardening temperature to the carburized tool blank, quenching the tool blank for formation of martensite.

12. The method as in claim 11, wherein the deformation of the tool blank in the working portion (14) includes a flow of the material in an entire cross-section of the tool and/or an ablation of material.

13. The method as in claim 11, wherein the carburizing takes place at a temperature between 900 C. and 1050 C.

14. The method as in claim 11, wherein the carburizing is performed by a carbon-containing carrier gas.

15. The method as in claim 11, wherein the applying the hardening is performed at a temperature that is higher than, equal to or lower than the temperature used for carburization.

16. The method as in claim 11, wherein the quenching comprises a freezing of the tool blank.

17. The method as in claim 11, wherein the base body consists essentially of a carburized chromium steel having an initial carbon content of not more than 0.7%.

Description

(1) Additional details of advantageous embodiments of the invention can be inferred from the description, the claims and the drawings. They show in

BRIEF DESCRIPTION OF THE DRAWINGS

(2) FIGS. 1 to 3 schematized representations of various embodiments of tools for textiles;

(3) FIG. 4 a schematized lateral view, partially in section, with cross-sections, of a sewing needle according to FIG. 2;

(4) FIG. 5 a temperature/time diagram for hardening the tool for textiles;

(5) FIG. 6 a greatly enlarged section of the working portion of a tool for textiles according to FIG. 1;

(6) FIG. 7 a greatly enlarged surface view of the working portion according to FIG. 6, in the region of its notch;

(7) FIG. 8 a greatly enlarged surface view of a working portion according to FIG. 6, in the region of its tip; and

(8) FIG. 9 a greatly enlarged surface view of a working portion according to FIG. 6, in the region of its tip, displaying inadequate surface quality.

DETAILED DESCRIPTION

(9) FIGS. 1 to 3 show various embodiments of a tool 10 for textiles. FIG. 1 shows the tool 10 for textiles as a felting needle 11. FIG. 2 shows the tool 10 for textiles as a sewing needle 12. FIG. 3 shows the tool 10 for textiles as a knitting needle 13. Furthermore, the tool 10 for textiles may be a warp-knitting needle, a tufting needle, a crocheting needle, a loop catcher, a sinker or more of the like.

(10) Typically, a tool for textiles, irrespective of design type, comprises a working portion 14 that can come into contact with threads, yarns or fibers. Furthermore, the tool 10 for textiles comprises a shank portion 15 that is disposed to support the tool for textiles in a receptacle and to guide and hold the working portion 14.

(11) Preferably, the tool 10 for textiles is manufactured from a longitudinal, cut material, for example, a section of wire, a strip of sheet metal or the like. After such a blank has been provided, it is plastically deformed by a deforming process in order to form the desired structures on the working portion 14 and the shank portion 15. On the working portion 14, these are typically substantially farther remote from the original form than in the case of the shank portion 15. Using the example of the felting needle 11, it can be seen that the diameter of the working portion 14 has been reduced substantially more than that of the shank portion 15. Likewise, the cross-section may also deviate clearly from the circular form. The form changes in zones that later are to display greater hardness are predominantly produced by plastic deformation. Deforming techniques are used that generate a large number of offsets. In particular the process is guided in such a manner that the zones that are subject to a strong plastic deformation are the ones that are later to display great hardness. It is also possible, that a machining process be substituted or added in order to produce or manufacture the desired geometric configurations of the surface. In so doing, the working portion may be imparted with zones having a surface/volume ratio that is greater than in other zones.

(12) Normally, the material existing in the working portion 14 has been more plastically deformed than in the shank portion 15. Furthermore, the surface/volume ratio may be greater than in other zones. This applies to the diameter reduction as well as to not specifically illustrated hooks and/or barbs provided on the working portion 15. The example of the sewing needle 12 shows that, in particular the region of its eye 16, as well as an adjoining thread groove 17 as well as its tip 18, have been subjected to a strong plastic deformation and, optionally, also to a material ablation in order to produce the desired structures. In the case of the knitting needle 13, the working portion 14 has also been considerably more strongly deformed than the shank portion 15. In particular its hook 19 that has been produced by plastic deformation is distinguished by a substantially greater flow of the material during manufacture than is observed on the shank portion 15.

(13) This situation is shown in greater detail by FIG. 4 where the example of the sewing needle 12 is used. The cross-section is essentially round in the region of the round shank. If the needle 12 was made of a wire, the diameter 20 is only minimally changed. The material in this case displays minimal compression and flow. In contrast, in the region of the thread groove 17, the cross-section 21 is considerably more deformed. During plastic deformation, the entire cross-section 21 was deformed. The degree of deformation is even greater in the region of the eye 16. Here, the cross-section 22 is split and extremely deformed overall. The degree of deformation is slightly less again toward the tip 18, as is shown by the cross-section 23.

(14) The sewing needle 12 has differing thicknesses in its shank portion 15 and its working portion 14. These are produced by a uniform hardening treatment. In so doing, it is possible with the method according to the invention to expose the needle 12, as well as any other tool 10 for textiles, on its working portion 14 as well as on its shank portion 15 to the same heating and cooling media. Nevertheless, despite the filigree structure of the tools for textile materials and the resultant approximately similar cooling rate of the shank portion 15 and the working portion 14, it is possible for different hardness profiles to form. For example, in the shank portion 15, the cross-section 20 may have a relatively high carbon percentage and great hardness in an outer zone 24 close to the surface, whereas a core zone 25 remote from the surface displays a lower carbon content and thus less hardness. Likewise, the cross-section 22 may also have a zone 24 close to the surface and a core-zone 25. Preferably, in this case however, the zone 24 close to the surface is thicker. The core-zone 25 remote from the surface is substantially smaller. It may also disappear completely. The carbon percentage in the zone 24 close to the surface of the shank portion 15 may be as great as or also less than the carbon content of the zone 24 close to the surface of the working portion 14, for example on eye 16. While the carbon content in the shank portion 15 decreases from the surface to the core, the carbon content in the working portion 14 may decrease minimally from the surface to the core. In addition, the carbon content in the working portion 14 may overall be greater than in the shank portion 15. It is also possible for the carbon content in the entire cross-section 22 (21 or 23) of the working portion 14 to be constant.

(15) Preferably, the tool 10 for textiles consistsbefore thermal treatmentof a chromium steel, for example X10Cr13, X20Cr13, X46Cr13, X65Cr13, X6Cr17, X6CrNi18-10 or X10CrNi18-8. Following the thermal treatment, these may contain additional carbon and chromium carbides.

(16) FIG. 6 shows a greatly enlarged detail of the working portion 14 of the felting needle according to FIG. 1 in the region of a notch 26. In the event of a 4000 times enlargement, the surface has the appearance in the region of the notch 26 as in FIG. 7. As is obvious, the appearance is defined by a number of roundish or even elongated carbide crystals, in particular chromium carbide crystals 27, that have the approximate shape of beans or peas and otherwise project from the plane 28 defined by the surface. Preferably, however, they do not form a cohesive layer and are hardly or not at all fused together. The individual roundish carbide crystals have a diameter of preferably 0.2 to 1 m. They are elongated and can have a longitudinal dimension between 2 and 3 m and a transverse dimension between 0.5 and 2 m.

(17) Outside the notch 26in particular in the region of the tip of the working portionthe surface is configured preferably as is obvious from FIG. 8, for example. The carbide crystals 27 are stochastically distributed over the surface 28 and have predominantly the form of roundish beans or peas. Again, an overall pimply appearing surface with a layer of carbide crystals embedded in the surface and partially projecting therefrom is formed. The individual carbide crystals 27 are at a distance from one another and are only rarely or not fused together. Fusible links 29 can be found only in a negligible minority of individual carbide crystals, i.e., preferably less than 20 percent thereof. The size of the individual carbide crystals 27 fluctuates between 0.3 m and 1.5 m. The plurality of the carbide crystals have an approximately roundish form with a diameter between 0.3 and 1.5 m. Elongated types have a transverse dimension of up to 1.5 m and a longitudinal dimension of up to 4 m.

(18) For better illustration, FIG. 9 additionally illustrates a less desirable surface configuration, in which the individual carbide crystals 27 are frequently bonded to one another by fusible links 29. As a result of this, irregularly formed cohesive carbide crystals are formed, these having a length and width exceeding 1 m, wherein some fused carbide crystal zones may also be larger than 2 m.

(19) The felting needle 11 and, in general, a tool 10 for textiles having a hardened surface structure according to FIGS. 7 and 8 on the working portion 14 is distinguished by low susceptibility to breakage, great hardness and low thread sliding resistances.

(20) A comparison of FIGS. 7 and 8 with FIG. 9 shows how the surfaces that have proved to be advantageous differ in quality from the surface shown by FIG. 9.

(21) The carbides in FIGS. 7 and 8 have a predominantly convex form and are largely free of concave zones, whereas the carbides in FIG. 9 have a predominantly concave form. The carbides in FIGS. 7 and 8 are largely free of fusible links.

(22) The carburization of the tool can be performed as follows:

(23) In a first step, a tool blank is provided, said blank consisting, for example, of a sheet metal strip, a wire section or the like, of a steel having a chromium content of at least 11 percent by weight. Here, steel is understood to mean an iron base alloy. Preferably the tool blank consists of X10Cr13, X20Cr13, X46Cr13, X65Cr13, X6Cr17, X6CrNi18-10 or X10CrNi18-8. This tool blank is now subjected to non-cutting and/or cutting deformation processes. These deformation processes compriseat least in the working portion 14plastic deformation processes. Referring to the plastic deformation processes, the material in the working portion 14 flows substantially more than in the shank portion 15. The deformation processes may comprise stamping, rolling, kneading and similar deformation methods. At the points of the working portion 14 that are to be fully hardened, the plastic deformation covers the entire material cross-section. In so doing, the more strongly deformed material displays more offsets than the more weakly deformed material. Furthermore, within the framework of plastic deformation or also within the framework of cutting processing, it is possible to bring about an increase of the surface/volume ratio.

(24) In a next working step the tool blank is brought to a carbonization temperature T.sub.C. It is preferably between 900 C. and 1050 C. Carbonization is performed in a vacuum furnace. It is supplied with a carbon carrier gas, for example acetylene, at a low pressure of a few millibar. This may be done with a continuous gas flow or also intermittently (pulsed). In this case the carbon accumulates in the surface layer. A part of the carbon reacts with the chromium contained in the chromium steel to form chromium carbide. The enlarged surface may cause a stronger carbon absorption in the affected zones during carburization.

(25) In the hardening process hereinafter, preferably the entire tool 10 for textiles is brought to a hardening temperature.

(26) In a subsequent step the tool 10 for textiles is quenched starting from the hardening temperature T.sub.H. In so doing, one or more cooling steps are employed. For example, the tool 10 for textiles may first be cooled to a quenching temperature T.sub.Q that is at, or minimally above, ambient temperature, for example. After a time of a few seconds to minutes, the tool 10 for textiles may then be cooled to a freezing temperature T.sub.K in order to remain there for an extended time (one minute to several hours). The manufacturing process then ends with the reheating of the tool 10 for textiles to ambient temperature T.sub.Z.

(27) With the concept according to the invention it is possible to attain tools for textiles having a hardness gradient in longitudinal as well as in transverse direction from the outside in, as well as from the working portion 14 toward the shank portion 15. A high wear resistance and a high rust resistance are achieved despite the high carbon content. A longer useful life is the result. The method does not require surface activation. Due to the carbonization at high temperature, the passive layers on the surface of the tool for textiles do not interfere with the carbon absorption.

(28) The tool 10 for textiles according to the invention consists of chromium steel, into which carbon has been embedded in locally varying amounts during a carbonization process. Thermal treatment achieves a formation of martensite with the maximum achievable hardness, in particular in those zones in which larger carbon fractions have been introduced. A tool for textiles with zones of differing hardnesses can thus be produced without having to subject the individual zones with differing hardnesses to different process conditions during the production process. The hardness is controlled on the basis of the degree of deformation of the tool for textiles.

LIST OF REFERENCE SIGNS

(29) 10 Tool for textiles 11 Felting needle 12 Sewing needle 13 Knitting needle 14 Working portion 15 Shank portion 16 Eye 17 Thread region 18 Tip 19 Hook 20-23 Cross-section 24 Zone of the shank portion 15 close to the surface 25 Core zone of the shank portion 15 remote from the surface 26 Notch 27 Carbide crystals 28 Level 29 Fusible links