CS241636B1 - A method of surface treatment of steel components of spinning devices of open-end spinning machines - Google Patents

Abstract

Method of surface treatment of steel parts of the spinning gear of spinning machines by ion nitriding. Ion nitriding is carried out in an atmosphere containing ammonia or a mixture of nitrogen and hydrogen with a pressure of 1 - 105 Pa at a temperature of 450 - 580 °C for 8-42 hours. The wear resistance of the parts is improved. It is used for parts of the spinning gear of textile spinning machines.

Description

Method of surface treatment of steel components of open-end spinning machines

Method of surface treatment of steel components of spinning machinery of spinning machines by ion nitriding. The ionic nitriding is carried out in an atmosphere containing ammonia or a mixture of nitrogen and hydrogen at a pressure of 1 - 105 Pa at 450 - 580 ° C for 8-42 hours. The wear resistance of the components is improved. It is used for spinning components of textile spinning machines.

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The invention relates to the surface treatment of steel components of an open-end spinning machine.

The components of the spinning mechanism determine the operational capability and the automatic operation of pretty spinning spinning machines. These components are so far made of aluminum alloys and the functional surfaces are cured by electrolytic oxidation. Until recently, this technological process was satisfactory, but due to the increase in the power of the spinning machines, it is also necessary to solve the increase in the service life of the components of the spinning device by using new technology.

For this purpose, coating technologies of aluminum components of the spinning device with various hard layers, applied by means of magnetron reactive deposition or by means of high-frequency plasma (eg Ti N, Si C, SiN) layers were tested. Although these thin layers x y x y x y showed an increase in hardness and abrasion resistance of the functional surfaces of the components of the spinning site, they did not satisfy the inadequate adhesion (the layer peeled off during operation). Among other technologies increasing surface hardness and abrasion resistance, a boriding method was used. The disadvantage of this method was the brittleness of the boride layers, which caused problems in the operation of the spinning device.

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The essence of the method of surface treatment of steel components of an open-end spinning machine according to the invention consists in that the components are ionically nitrided in a working atmosphere containing ammonia or a mixture of nitrogen and hydrogen, the hydrogen content being three times higher than nitrogen and can be reduced up to zero value; total pressure ranging from 1 to 10 bar, at 450 to 580 ° C, for 8 to 42 hours. The working atmosphere may be formed such that it may contain max. 1% of a gaseous hydrocarbon, such as methane, and oxygen at the end of the process.

By utilizing the proposed ion nitriding technology in the components of the spinning mechanism of open-end spinning machines, the service life of these components can be increased several times. The value of the increase in service life will depend on the type of fibers to be processed, the choice of steel from which the component will be made and the selected ion nitriding parameters. The choice of steel will take into account, on the one hand, the requirement to increase durability and, on the other hand, the price of steel. Furthermore, good machinability of the components is ensured, since the advantage of the method according to the invention is that the components of the spinning device do not need to be quenched and tempered prior to ionic nitriding and can therefore be machined to final dimensions in the annealed condition. At the same time, the costs of hardening and tempering as well as the machining costs of components are eliminated. Another advantage of ion nitriding over sputtering is that the diffusion layer is formed evenly according to the geometrical shape of the components, which in this case cannot be ensured by the sputtering method for the entire range of components of the spinning site.

The advantage of ionic nitriding over conventional nitriding is that the surface layer of nitrides produced in an anomalous glow discharge has excellent frictional and anticorrosive properties, is compact, free of pores and does not crack, thus increasing the resistance of components to abrasive wear and chemical influences. In addition, there is additional energy and labor savings, as the resulting layers do not have to be reground, which is necessary after conventional nitriding. Also, the growth rate of the layer is at ionic

- 3 nitriding greater. 2 «β3β

The advantage of ion nitriding over thin-film sputtering methods is that a wide range of components can be processed in an ion nitriding device, the cost of this technology being much lower and the device available. The ionic niiridaCg technology is less demanding on surface roughness and surface cleaning quality prior to sputtering. The diffusion character of the layer resulting from ionic nitriding also results in superior layer adhesion, much better than sputtering.

In order to utilize the proposed technology of the invention, it is necessary to manufacture the components of the spinning device from any steel which can be selected with regard to the economics of component manufacture and the stressing method. Further details of the pressure, temperature and composition of the atmosphere are set forth in the following description of the invention.

When determining the optimal temperature of the ion nitriding process, it is necessary to take into account not only the fact that at higher temperatures the growth of the nitriding layer (surface interlayers of iron nitrides and the diffusion zone) is faster, but it is necessary to take into account the required layer quality. relatively low nitriding temperatures. A nitriding temperature in the range of 470 ° C to 52 ° C is recommended for the treatment of high &fBX ± abrasion fibers.

The determination of the optimal length of the ion nitriding process is indirectly dependent on the nitriding temperature, i.e. the higher the nitriding temperature is selected, the shorter the time required to form a nitriding layer of a given depth. The minimum duration of the ion nitriding process is 8 hours or there will be no continuous surface interlayer of nitridic phases in less time, which guarantees good friction properties. However, since the increase in nitriding layer depth slows considerably with increasing time, it is not economical to extend the nitriding time beyond 42 hours. Furthermore, the depth of the nitriding layer, especially the surface interlayer of the nitridic phases, depends on the type of steel used. For steels with higher alloy content, a nitriding time of at least 16 hours is therefore recommended.

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The determination of the optimum nitrogen to hydrogen ratio in the working atmosphere depends on the desired quality and the desired growth kinetics of the nitriding layer. When processing fibers that cause high abrasion of components, it is recommended to select an atmosphere in a ratio of N ₂ : H 2 = 1: 3, thereby partially prolonging the nitriding time, but achieving a high consolidation of the nitriding layer. When processing less abrasive fibers, the hydrogen content can be minimized. Good friction properties of the layer can also be achieved by admitting a hydrocarbon gas or an oxygen-containing gas to the working atmosphere of nitrogen and hydrogen.

The determination of the optimum working pressure depends on the size of the functional openings and the shape complexity of the components. If the holes in the component do not need to be nitrided, they can be blinded or the working pressure selected such that the glow discharge does not burn in the holes. If the holes have to be ion-nitrided, the working pressure must be chosen so that the glow discharge burns in them. In addition to the very small diameters that cannot be nitrided, for each diameter there is a working pressure range at which the orifice can be nitrided. However, the hollow discharge area must be avoided, as the hole or the entire component may overheat. Similarly, due to the shape complexity of the components of the spinning device, it is necessary to select a working pressure such that ion nitriding occurs at all points to be nitrided.

Thus, for example, in spinning rotors having vent holes, e.g. / 5 mm and holes for pressing the rotor onto the bearing pin, eg. ó 10 mm, different working pressures can be selected for ion nitriding, which can be as follows:

- If the ventilation or compression holes are to be nitrided, the working pressure must be selected in the range (5.5 to 7). IQ ² Pa

- if the vent hole does not need to be nitrided and the press hole is to be nitrided, a working pressure in the range (4 to 7) must be selected. 10 ^ Pa,

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if none of the apertures need to be nitrided, ni2 can be tridied in a pressure range (0.1 to 1.5). 10 Pa, or the crimping hole can be blinded and nitrided in the pressure range (0.1 to 3). 10 ² Pa and (5.5 to 7) .10 ² Pa. Another possibility is to blind all holes and nitriding at any pressure in the range of 1 to 10 Pa.

If some of the components of the spinning device are required primarily to improve the frictional properties and not the abrasion resistance, ionic nitriding can be performed very well with the addition of hydrocarbon gas or oxygen, or both, resulting in carbonitrides, oxinitrides or oxicarbonitrides with excellent friction properties.

The increase in surface hardness and microhardness relative to the base material depending on the steel used and the nitriding heat is shown in the following table:

Temperature Carbon Nitride-Steel; ce Hardness increase:

C) (Hv 5)

47 ° to 51 ° 13o to 150 510 ° to 5 & 0 ° 100 to 150 Example J.

and low alloy Micro-Medium alloy steel increase; Increase Increase Micro-

hardness: hardness; hardness; (Hm 50) (Hv 5) (Hm 50) 500 to 750 400 to 850 700 to 1650 400 to 600 100 to 650 240 to 1400 annealed steel ČSN 15340 was nitrided

sO at ⁴⁷⁰ C for 35 hours in an atmosphere formed by a mixture of nitrogen and hydrogen in a ratio of 1: 3 at a pressure Pa and 1,3.10 initial microhardness Hm 250 50 371 Hv and the hardness was increased to 5 Hm 50 1950 and 1100 Hv 5.

Example 2.

Low alloy steel DIN 14 220 was nitrided at 500 ° C for 8 hours in an atmosphere at a pressure čpavHkové ^£ 3.10 Torr

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- β and values of the original microhardness 192 Hm 50 and hardness 173 Hv 5 were increased to 679 Hm 50 and 700 Hv 5.

Using the method according to the invention, it is possible to maximize the lifetime of all components of an open-end spinning machine by improving their resistance to the stresses by suitably selected ion nitriding technology and by the appropriate choice of the steel from which they will be made. In view of the results of the foregoing variants and in view of the versatility of ionic nitriding in terms of the steels used and the shape complexity and dimensions of the components, ionic nitriding currently appears to be the optimum technology under the conditions established by the invention.

In addition to increasing the service life of the components of the spinning device, the quality of the spun fibers also increases due to the low friction coefficient of the nitrided surface with which they come into contact.

Claims (3)

SUBJECT OF THE INVENTION 1. A method of surface treatment of steel components of an open-end spinning machine, characterized in that the components are ion-nitrided in the pressure range 1 to 10 ³ Pa at a temperature of 450 ° to 580 ° C for 8 to 42 hours in a working atmosphere containing ammonia or a mixture of nitrogen and hydrogen, the hydrogen content being at most three times the nitrogen and can be reduced to zero. 2. A process according to claim 1 wherein the working atmosphere contains at most 1% hydrocarbon gas, e.g. methane. 3. The process of claim 1 wherein oxygen is admitted to the working atmosphere at the end of the ion nitriding process.