EP0020399B1 - Spinning steel ring for ring frames and continuous ring twists - Google Patents

Abstract

The spinning steel ring (1) is partially hardened, that is to say in a local area (8) of the ring wherein there is provided a traveller flange (2) with its guiding surface (3). This area (8) is comprised of an outer softer running-in layer (11) and of a hardened core (9). The running-in layer (11) comprises a superficial layer of iron nitride (7) which gradually transforms into an austenitic and martensitic transition layer (10) containing nitrogen of which the austenite contents decreases inwardly, thereby enhancing the hardness. After the iron nitride layer (7) has been worn, the traveller may slide onto the transition layer (10) of which the hardness increases gradually and which becomes more resistent as it wears. In this manner, the running in time is considerably reduced and it allows without any trouble after the running-in. The dimensions of the spinning ring (1) are strictly maintained due to the fact that the hardening is limited to the area (8).

Description

The invention relates to a spinning ring made of steel for ring spinning and ring twisting machines with a rotor guide surface, which has a hardened structure and an outer layer with a non-metal diffused into it.

A known spinning ring of the aforementioned type (for example US Pat. No. 2,987,871 or US Pat. No. 3,084,501) is subjected to case hardening at 830 ° C. and then sulfurization in a salt bath at approx. 565 ° C. to produce it. whereby a soft, sulfur-containing surface layer with a thickness of 50µ up to a few tenths of a millimeter is achieved. This is followed by a further case hardening or induction hardening at about 855 ° C in order to restore the hardness lost during the sulfurization. Due to the sulfur introduced, the outer hardened layer has lubricating properties which can reduce the run-in time for the runner. However, this run-in layer can be completely removed by the runner. In this way, not only are the desired lubricating properties of the rotor guide surfaces lost on the known ring, but the hardened, sulfur-free steel base is exposed, so that the known disadvantages of welding the rotor and ring occur again. The fully hardened ring has e.g. also no longer the necessary shape obtained during the shaping, e.g. Roundness, because it is known to be affected by the hardening that occurs above the structural transformation temperature. Any out-of-roundness that is evened out in the outer layer therefore affects the rotor again on the hardened steel base. The known spinning rings with a hardened structure therefore do not have the desired properties as are required for a finished, usable ring.

Another known spinning ring made of hardened steel (CH-A-430.522) has an outer, approximately 3-50 .mu.m deep surface layer made of soft, unhardened steel, which is caused by the removal of carbon as a result of annealing during the hardening process and therefore a lack of structural change during the hardening process. Despite the smoothing by the runner when running in while removing the mild steel, there is a ferritic surface due to the decarburization, which favors the tendency to seize the runner. This known spinning ring also has the disadvantage that as the soft layer progresses, the rotor gets onto the hardened steel base and e.g. the dimensional accuracy of the ring is also impaired when it is annealed above the structural transformation temperature. The lack of an alloy component extracted during the hardening process does not therefore remedy the disadvantages of a ring made of hardened steel with a non-metal doped in the surface layer.

From FR-A-1333500 a method for gas nitriding non-alloyed iron is also known, in which a layer of martensite is formed below an outer layer.

The outer layer thus formed has good anti-friction properties, which are increased by the natural porosity of the layer.

It is the object of the invention to create a spinning ring of the type mentioned at the outset without the disadvantages of the previously known spinning rings with an outer running-in layer on the rotor guide surface, by means of which a rapid passivation, i.e. Reduction of their tendency to adhesion, and adaptation to the rotor shape and thus safe operation is to be achieved.

The object is achieved according to the invention in that the ring in an hardened zone containing the rotor guide surface has an outer, nitrogen-containing, softer inlet layer than the hardened steel with an increasing cross-section inward hardness, and in that the hardened zone locally on a part containing the rotor guide surface of the ring is limited and connects to an unhardened area of the ring.

The invention is based on the knowledge that the behavior of nitrogen and its influence on the structure of steel are used to control the structural change in the hardened zone and thus the structure formation in the nitrogen-containing area of the spinning ring and thus in the inlet layer.

In the ring according to the invention, therefore, an outer iron nitride layer enriched by diffusion with nitrogen can be formed, which gives a nitrogen-rich, softer structure containing hardened austenite during hardening. It is thus possible to reverse the known undesirable effects and properties of the non-metallic component nitrogen in the steel structure and those of a hardened structure for a spinning ring by combining them into an advantageous effect. In the ring according to the invention, therefore, the running-in layer is preferably present with an austenitic-martensitic structure, the austenite content of which decreases in the direction of the hardened steel base to the same extent as the content of the nitrogen which has diffused in, and thus results in the increasing hardness inside. In this way, a continuous in the structure of the structure of the running-in layer which transitions hardened steel base is anchored, which anchors the running-in layer in the steel base by the nitrogen diffused therein during hardening and avoids a sudden transition of the structure from the running-in layer to the hardened steel base. With the spinning ring according to the invention, the runner can continuously access the structure, which is becoming increasingly older and more resistant to wear and tear, when the run-in layer is removed while the run-in layer is removed.

The spinning ring according to the invention is thus protected against adhesive scuffing and the occurrence of welded-on material, as has been the case with the ungreased sliding of two metallic materials onto one another and therefore between a rotor and the previously known spinning rings.

Even after the runner has been worked into the run-in layer, a runner guide surface can therefore be created for the runner which, owing to its nitrogen content, has a high feed resistance and does not lead to the notorious welding of the runner and ring. During the run-in, e.g. any remaining shape errors in the rotor guide surface due to the softer running-in layer have been eliminated.

In the spinning ring according to the invention e.g. the running-in layer is quickly smoothed due to its lower hardness in the outer area, so that even at rotor speeds e.g. of more than 30 m / sec there is no risk of seizure in the rotor guide surface. A considerable shortening of the running-in process can be achieved without any appreciable reduction in the normal production speed, because the runner can continuously reach a surface of increasing hardness and thus increasing stability, damage to the runner guide surface such as e.g. by G. Stähli, signs of wear on the treads of high-speed steel spinning rings, causes and formation mechanism, Melliand Textilbereichte 53 (1972), pages 1101 to 1103, are avoided. For example, after 1-3 bobbin changes, i.e. after a short time to full production speed, e.g. to a runner speed of 34 m / sec, so that e.g. there is also no time-consuming entry schedule for ring and runner. Less runner wear and thus a longer service life for the runner are achieved, as a result of which the number of thread breaks can also be reduced.

To produce the spinning ring according to the invention, after the final shaping of the same, the non-metallic component nitrogen is introduced into the surface of the ring made of unhardened steel at a temperature below the structural transformation temperature and an outer, nitrogen-rich iron nitride layer is formed The structural transformation temperature is preferably hardened in a locally limited zone which contains the rotor guide surface and remains restricted to the part of the ring which contains the rotor guide surface, as a result of which the finished shape of the ring can be maintained unchanged. The dimensional accuracy of the spinning ring, e.g. Roundness and flatness of the same are guaranteed, which is known to always be impaired when the entire ring body is hardened. The partial hardening can be controlled in such a way that e.g. the entire core of a flange cross section is hardened or only a hardened layer is present and a core made of unhardened steel remains in the flange cross section.

• Fig. 1 einen Spinnring aus härtbarem Stahl, im Schnitt, in schematischer Darstellung,
• Fig. 2 einen Teil des Spinnringes von Fig. 1, in vergrösserter Darstellung,
• Fig. 3 einen Teil eines Spinnringes aus härtbarem Stahl, im Schnitt, in schematischer, vergrösserter Darstellung und
• Fig. 4 einen Teil eines anderen Spinnringes aus härtbarem Stahl, im Schnitt, in schematischer, vergrösserter Darstellung.

The invention is explained below in further embodiments with reference to the drawing. Show it:

• 1 is a spinning ring made of hardenable steel, in section, in a schematic representation,
• 2 shows part of the spinning ring of FIG. 1, in an enlarged view,
• Fig. 3 shows a part of a spinning ring made of hardenable steel, in section, in a schematic, enlarged view and
• Fig. 4 shows a part of another spinning ring made of hardenable steel, in section, in a schematic, enlarged view.

A spinning ring 1 made of steel, such as can be used for a ring spinning or ring twisting machine, has an annular upper rotor flange 2 with a rotor guide surface 3 for receiving a rotor 4 guiding a thread. A flange 5, which is also annular, is connected to the flange 2 , on which an outwardly angled, annular mounting flange 6 for attaching the spinning ring 1 is formed on a ring bench of the machine, not shown. The spinning ring 1 is made in one piece with the flange 2, the ring web 5 and the limiting flange 6.

As also shown in FIG. 2, the spinning ring 1 has an outer layer 7 made of iron nitride on its entire surface in the steel. In a locally limited zone 8, in which the flange 2 with the rotor guide surface 3 is located, the spinning ring 1 made of unhardened steel is fully hardened in the entire core 9 of the zone 8, so that in the flange 2 there is a fully hardened structural ring with an outer contour of the flange 2 given rotation surface RF is formed. In zone 8, a transition layer 10 is formed between the iron nitride layer 7 and the hardened steel base in the core 9, ie the hardened structure 9a thereof, with a hardness which is lower than that of the hardened steel base, and which together with the iron nitride layer 7 in the Zone 8 gives a run-in layer 11 for the rotor 4. The hardened zone 8 extends from a flange upper edge 2a beyond the rotor flange 2 to an immediately adjoining area 12 of the ring web 5 at a height of the spinning ring 1 indicated by A, which is less than a total height B of the spinning ring 1. In the area 12 of the ring web 5, the hardened zone connects to an area 13 of the spinning ring 1 made of the uncured steel. The zone height A is preferably chosen to be so large that all areas of the outer surfaces of the spinning ring 1 that come into contact with parts of the rotor, for example also with rotor ends 4a, lie within the hardened zone 8. Between the hardened structure 9a in zone 8 and the remaining area 13, which has an unhardened structure 13a, there is a delimited structure transition 14 which results from the temperature profile or temperature gradient in the steel material during hardening.

To form the running-in layer 11, the spinning ring 1 manufactured with the desired usable dimensions is entirely nitrided in its surface at a temperature which is below the structural transformation temperature of the steel used, preferably at 500-600 ° C, e.g. at 560-580 ° C, the dimensional accuracy of the spinning ring 1 remains guaranteed. Bath nitriding, e.g. According to the so-called Tenifer process, also called the tuff ride process, as stated in Durferrit House Bulletins, Issue 35, December 1962, by Degussa, Dept. Durferrit, Frankfurt / Main, or a e.g. short-term gas nitriding takes place, e.g. by G. Stähli et al., Comparative Investigations on Bad Nitrided and Nicotrated Samples, Material und Technik, 2 (1974), No. 3, 126-135. In this case, the iron nitride layer 7, e.g. with about 10-12 weight percent nitrogen. Depending on the duration and intensity of the nitriding and the type of steel, the layer 7 can have a thickness C of up to approx. 50, e.g. 5-10µ and compared to the hardness of the unhardened steel with e.g. a Vickers hardness of 100-200 HV, a greater hardness, e.g. a Vickers hardness of 400-600 HV can be achieved. By diffusing nitrogen a few tenths of a millimeter beyond the layer thickness C in a small amount of less than 0.1 percent by weight, a so-called diffusion layer (not shown) can result in the ferrite of the uncured steel.

The spinning ring is then in the locally limited zone 8, i.e. only partially, while heating to temperatures above the structural transformation temperature of the steel used, e.g. to 800-900 ° C, and cooling, i.e. Harden, hardened. When heated to the hardening temperature, nitrogen diffuses from the iron nitride layer 7 into the steel base, i.e. into the steel base inwards, which leads to a transition zone corresponding to the transition layer 10 with a falling nitrogen content away from the layer 7 inwards. During the subsequent hardening, a transformation of austenite into martensite is inhibited in accordance with the gradient of the nitrogen content in the transition zone and the transition layer 10 is formed with a decreasing content of austenite and an increasing content of martensite.

As a result of the residual austenite content, the layer 10 therefore has a lower hardness than the hardened steel base of the core 9 containing austenite-free martensite structure and has e.g. starting from a Vickers hardness of around 700 HV, increasing hardness inwards except for e.g. a Vickers hardness of more than 700 HV, e.g. 900 HV, owning steel base.

In the manner described above, the spinning ring 1 can be formed in the locally delimited zone 8 in succession with the inlet layer 11 from the remaining iron nitride layer 7 and the adjoining transition layer 10 with increasing hardness and the core 9 made from hardened steel. After hardening, the spinning ring 1 has a fine-porous surface in the hardened zone 8. The spinning ring 1 is therefore preferably mechanically in zone 8, e.g. reworked by grinding or slurry blasting, whereby the running-in layer 11 with the outer iron nitride layer 7 is exposed and smoothed and a low-pore surface, free of processing traces of manufacture and scale, is achieved. The rotor 4 can thus work smoothly in the initially soft iron nitride layer 7 and remove it quickly and then reaches the transition layer 10 to an increasing hardness thereof, thereby preventing damage to the running surface.

The iron nitride layer 7 also achieves a substantially improved corrosion resistance for the spinning ring 1, as a result of which the covering of the spinning ring 1 e.g. with an anti-rust agent.

The partial hardening of the spinning ring 1 can be carried out by means of electrical induction hardening, e.g. by means of a completely closed, non-overlapping induction coil which is connected to the part of the ring 1 to be hardened, i.e. the flange 2 of the same, e.g. is applied around its outer circumference. This allows zone 8 to be seamless, i.e. be formed without an abutting location or overlap. As a result of the steep drop in temperature in the area 13 lying outside the sharply delimited electrical field, the well-defined structural transition 14 occurs, which e.g. is known to be clearly recognizable in a micrograph with the unarmed eye.

The partial hardening of the spinning ring 1 in the zone 8 can, for example, depending on the type of steel, a thickness D and a height E of the flange 2, the desired height A of the zone 8 with ent accordingly adjusted intensity, or high energy density and / or duration, for example by means of high-frequency (HF) or medium-frequency (MF) induction hardening for a short time, for example for a duration of only seconds, in other words in the range of seconds, or in fractions of seconds. With HF hardening, hardening can be achieved, for example, with flange thickness D in the range of 3-5 mm and flange height E in the range of 1.5-2 mm, in which hardened structure 9a is at a zone height away from flange top edge 2a of, for example, 0.5-1.0 mm. With an MF hardening, the spinning ring 1 can be hardened from the upper edge 2a to the ring web 5 at a height in the range of 2-3 mm. The structural hardening can also be carried out by means of electron beam, laser beam or flame hardening. Depending on the shape of the spinning ring and / or the flange and depending on the hardening process, the hardening can be carried out at a desired zone height from the outside or the inside of the spinning ring. There can also be a so-called turning ring with a double flange and with two hardened zones, which are limited to the two flanges.

A flame-hardenable steel is preferably used as the type of steel. For this, e.g. Steel grades as specified by ISO standard No. 683 / X) i-1972, e.g. a Cf45 or Cf53 steel, or a steel specified in accordance with DIN standard No. 17.212, e.g. a Cf70 or 49CrMo4 steel, or a 100Cr6 steel, e.g. in the steel-iron material sheet nos. 200 and 350 of the iron and steel industry standards, Association of German Ironworkers, Düsseldorf.

In the embodiment according to FIG. 3, a spinning ring 16, as can also be used on a ring spinning or ring twisting machine, has a locally limited, hardened zone 17, in which an upper, adjoining a ring web 18 and machined therewith from one piece Flange 19 lies with a rotor guide surface 20. The zone 17 extends from a flange upper edge 19a beyond the flange 19 to an immediately adjoining area 21 of the ring web 18 at a height F which is less than a total height G of the spinning ring 16 which is shown in part. In zone 17, a run-in layer 22 for a rotor (not shown) is formed in the surface of the steel, which has an outer layer 23 containing iron nitride, which extends over the entire outer surface of the spinning ring 16, to which one is hardened in zone 17 this limited, nitrogen-containing transition layer 24 connects, in which there is an austenitic-martensitic structure with an inwardly decreasing austenite content and therefore increasing hardness. Due to the partial hardening of the spinning ring 16, which can be carried out as described in the embodiment according to FIG. 1, a layer 25 is formed in the zone 17 which adjoins the transition layer 24 and is hardened in accordance with the contour of the flange 19, so that in the hardened zone 17 successively the run-in layer 22, the hardened layer 25 and a core 26 made of unhardened steel are present. Between the hardened layer 25 and the unhardened structure 26a there is again a delimited structure transition 27. The inlet layer 22 has the same properties as were described for the inlet layer 11 1 of the embodiment according to FIGS. 1 and 2. The contour hardening can e.g. by so-called pulse hardening in a fraction of a second, e.g. in the range of milliseconds, e.g. by G. Stähli, "The short-term surface hardening of steel by high-energy impulses", Material und Technik 1974, No. 4, pages 163-171. The hardening limited to the contour in zone 17 has the advantage that the risk of the spinning ring being distorted and thus e.g. an occurrence of out-of-roundness can be further reduced.

The embodiment according to FIG. 4 shows a spinning ring 28 made of steel, with an annular web 29 and an attached flange 30 with a rotor guide surface 31 and with a hardened zone 32 which is locally limited to a part of the spinning ring 28 containing the flange 30. In zone 32 there is an inlet layer 33 in the surface of the steel, to which a hardened steel base 34 adjoins. The entire thickness H of the running-in layer 33 consists of an austenitic-martensitic structure 33a with a decreasing austenite content, continuously passing into the hardened steel base 34, with a decreasing austenite content, so that the running-in layer 33 hardens inwards again. By appropriate temperature control during hardening of an iron nitride layer 36 previously formed in the surface of the unhardened steel, it can be achieved that the iron nitride is broken down and residual austenite is formed in the layer 33 up to the outer surface 35. Due to the partial hardening of the spinning ring 28, a structure transition 38 is again present between the hardened structure 33a of the steel base 34 and an unhardened region 37 of the spinning ring 28.

Claims (23)

1. Steel ring for ring spinning and ring twisting machines with a traveller guide surface which has a hardened structure and an outer layer containing a diffused-in non-metal characterised in that, in a hardened zone (8; 17; 32) containing the traveller guide surface (3; 20; 31), the ring (1; 16; 28) has an outer, nitrogen-containing running-in layer (11; 22; 33) which is softer than the hardened steel and in section is of increasing hardness inwardly, and in that, the hardened zone (8; 17; 32) is locally limited to a part (2, 12; 18, 21; 30) of the ring (1; 16; 28) containing the traveller guide surface (3; 20; 31) and adjoins an unhardened region (13; 26; 37) of the ring (1 ; 16; 28).

2. Ring according to patent claim 1, characterised in that the whole core (9) of the zone (8) of the ring (1) containing the traveller guide surface (3) is hardened.

3. Ring according to patent claim 1, characterised in that the running-in layer (22), a hardened layer (25) and a core (26) of unhardened steel succeed one another in the hardened zone (17).

4. Ring according to patent claim 1, characterised in that the running-in layer (11; 22) has on the whole external surface of the ring (1; 16) an outer iron nitride layer (7; 23) which is adjoined in the hardened zone (8; 17) by a nitrogen-containing, austenitic-martensitic transition layer (10; 24) with the increasing hardness, merging continuously into the structure (9a) of the hardened zone (8; 17).

5. Ring according to patent claim 1, characterised in that the hardened zone (8; 17; 32) has a Vickers hardness of more than 700 HV.

6. Ring according to patent claim 1, characterised in that a clearly defined transition (14; 27; 37) is present between the locally limited hardened zone (8; 17; 32) and the unhardened structure (13a) of the steel.

7. Ring according to patent claim 1, characterised in that the steel is flame hardenable.

8. Ring according to one of patent claims 2 to 7, characterised in that the steel is for example an 1 00Cr6, Cf45, Cf53, Cf70 or 49CrMo4 steel.

9. Ring according to patent claim 1, characterised in that the hardened zone (8; 17; 32) and the unhardened region (13; 26; 37) are provided in the ring (1; 16; 28) made in one piece.

10. Ring according to patent claim 1, characterised in that in the locally limited hardened zone (8; 17; 32) a ring, the structure of which is hardened throughout, is present over the whole periphery under the running-in layer (11; 22; 33).

11. Ring according to one of patent claims 1 to 3, characterised in that a part of the ring (1; 16; 28) containing the hardened zone (8; 17; 32) is a traveller flange (2; 19; 30) located on a web-portion (5; 18; 29) of the ring.

12. Ring according to patent claim 11, characterised in that the hardened zone (8; 17) extends beyond the traveller flange (2; 19) into the immediately adjoining region (13; 21) of the web-portion (5; 18) of the ring.

13. Ring according to one of patent claims 1 to 12, characterised in that the ring (1; 16; 28) has a fine-pored outer peripheral layer in the hardened zone (8; 17; 32).

14. Ring according to one of patent claims 1 to 12, characterised in that the ring (1; 16; 28) has in the hardened zone (8; 17; 32) an outer surface having few pores.

15. Ring according to patent claim 1, characterised in that the hardened zone (8; 17) has a height (A; F) which is less than the overall height (B) of the ring (1; 16).

16. Method for the production of a steel ring with a traveller guide surface for ring spinning and ring twisting machines, in which after the formation of the ring a non-metal is introduced through the surface thereof at a temperature lower than the structure-transition temperature and thereafter hardening is effected at a temperature above the structure-transition temperature characterised in that an outer, nitrogen-rich layer of iron/nitride is formed in the outer surface of the ring of unhardened steel and thereafter the ring is hardened in a locally limited zone containing the traveller guide surface.

17. Method according to patent claim 16, characterised in that the whole outer surface of the ring is nitrided below the structure transition temperature and a martensitic structure containing remnant austenite is formed in the outer layer in the locally limited zone.

18. Method according to patent claim 16 or 17, characterised in that the iron/nitride layer is formed with a nitrogen content of approximately 10 per cent by weight.

19. Method according to patent claim 17, characterised in that, in the locally limited zone, the whole iron/nitride layer and a zone of the steel substrate adjoining thereon are converted into the austenitic-martensitic structure.

20. Method according to patent claim 16 or 17, characterised in that only a traveller flange located on a web-portion of the ring is hardened.

21. Method according to patent claim 16 or 17, characterised in that only the traveller flange and an immediately adjoining region of the web-portion of the ring are hardened.

22. Method according to patent claim 16, characterised in that the locally limited zone is hardened with high energy density, for example by electrical induction, electronic beam or laser beam, during an interval of the order of seconds or fractions of a second.

23. Method according to patent claim 16, characterised in that the outer surface of the ring is mechanically worked in the locally limited zone after the hardening to remove scale and porosity.

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