JP2011064218A - Wear-resistant chain - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wear-resistant chain markedly improved in wear resistance by coating the surfaces of pins with hydrogen-free DLC of high hardness with good adhesiveness. <P>SOLUTION: The problem is solved by the wear-resistant chain formed of a plurality of link plates bendably connected to each other by the pins having: a carbide coat formed on a base material by diffusion coating; and a DLC coat on the carbide coat. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a chain in which a plurality of link plates such as a roller chain, a bush chain, and a silent chain mainly used as a timing chain of an automobile are connected to each other so as to be able to bend alternately by pins, and more specifically, by surface treatment of pins. The present invention relates to a chain with improved wear resistance.

  Conventionally, a hard carbide layer such as chromium carbide or vanadium carbide has been formed on the surface of the pin in order to suppress wear caused by sliding between the pin and bushing or the pin and link plate, which causes chain elongation of an automobile timing chain. (For example, refer to Patent Document 1).

  In addition, in order to improve the wear resistance, it has been attempted to apply a DLC coating on the surface of the pin (see, for example, Patent Documents 2 and 3).

JP 2004-293586 A JP 2006-29462 A JP 2005-291349 A

  However, due to the recent increase in engine displacement and the increase in chain tension and the decrease in the amount of additives such as P and S in engine oil, the chain usage environment in automobile timing systems is an environment where wear is promoted. . Therefore, the conventional measure of forming a hard carbide layer on the surface of the pin is insufficient, and a measure for further reducing wear elongation is required.

  Further, as a countermeasure for applying DLC coating on the surface of the pin, when an operation test with a chain was carried out, peeling occurred and there was a problem in adhesion. This is considered to be because the residual compressive stress of DLC is large and the difference in hardness between the base material and DLC is large.

  Moreover, the characteristics of DLC vary greatly depending on the hydrogen content. Particularly, the hardness can be as large as 1000 to 5000 Hv. Although it is desired to use a hydrogen-free DLC film having a higher hardness for improving the wear resistance, it has been difficult due to the aforementioned adhesion problem. In Patent Document 3, it is stated in the paragraph [0011] of the same document that “the structure of the DLC layer is usually an amorphous structure containing some hydrogen and has a diamond bond or a graphite bond”. It is not envisaged to use a hydrogen-free DLC film as is done.

  Therefore, the technical problem to be solved by the present invention, that is, the object of the present invention is to provide a wear-resistant chain in which the hardness of hydrogen-free DLC is coated on the surface of the pin with high adhesion and the wear resistance is remarkably improved. Is to provide.

  First, the invention according to claim 1 is a wear-resistant chain in which a plurality of link plates are connected to each other so as to be bent alternately by pins, and the pins are provided with a carbide coating formed on a base material by a diffusion penetration method. The problem is solved by having a DLC coating on the carbide coating.

  Here, the diffusion penetration method in the present invention means a carbide coating that reacts with carbon contained in the base material to form carbide by diffusion penetration of carbide forming elements such as chromium and vanadium. Specifically, there are a powder pack method, a coating method, a plating heating method, a molten salt method, a fluidized bed furnace method, and the like. The DLC in the present invention means a diamond-like carbon, that is, a carbon film having characteristics similar to diamond known as diamond-like carbon, and is one of new materials for hard thin films.

  The invention according to claim 2 further solves the problem in the wear-resistant chain according to claim 1, wherein the carbide coating is a chromium carbide coating or a vanadium carbide coating.

  The invention according to claim 3 is the wear-resistant chain according to claim 1, wherein the carbide coating is formed on the base material of the pin, and the vanadium carbide formed on the chromium carbide coating. By comprising a film, the said subject is further solved.

  According to a fourth aspect of the present invention, in the wear resistant chain according to any one of the first to third aspects, after the carbide coating is formed, a quenching and tempering treatment is performed, and then a polishing treatment is performed. Thus, the above-described problem is further solved.

  The invention according to claim 5 further solves the problem in the wear-resistant chain according to any one of claims 1 to 4 because the DLC film is hydrogen-free.

  According to the first aspect of the present invention, in a wear-resistant chain in which a plurality of link plates are connected to each other by a pin so as to be able to bend, the pin has a carbide coating formed on the base material by a diffusion penetration method. And having a DLC coating on the carbide coating, the carbide coating formed by the diffusion penetration method has strong adhesion to the base material, and the hardness of the pin base material and the DLC coating. Since the difference between the hardness of the DLC film and the hardness of the DLC film is moderated by the carbide film having an intermediate hardness, the adhesion of the DLC film to the pin base material is improved, and the wear resistance of the chain is improved.

  In addition, since the hard carbide coating is provided on the pin base material, even if the DLC coating is peeled off, the pin base material is not exposed, thereby preventing the wear of the base material from being accelerated.

  According to the invention according to claim 2, in the wear-resistant chain according to claim 1, the carbide coating is harder than the base material of the pin and softer than the DLC coating because the carbide coating is a chromium carbide coating or a vanadium carbide coating. Therefore, the adhesion between the pin base material and the DLC film is improved.

  According to the invention of claim 3, in the wear-resistant chain according to claim 1, a chromium carbide film formed on the base material of the pin and a vanadium carbide film formed on the chromium carbide film. Since the hardness of the pin base material, the hardness of the chromium carbide coating, the hardness of the vanadium carbide coating, and the hardness of the DLC coating are gradually increased, the adhesion between the pin base material and the DLC coating is further improved. In addition, the wear resistance of the chain is improved.

  According to the fourth aspect of the present invention, in the wear resistant chain according to any one of the first to third aspects, after the carbide coating is formed, the quenching and tempering processes are performed, and then the polishing process is performed. This improves the adhesion between the carbide coating and the pin base material and improves the adhesion between the carbide coating and the DLC coating, further improving the adhesion between the pin base material and the DLC coating and improving the chain resistance. Abrasion is improved. In addition, by polishing the carbide coating as the underlayer, the surface roughness is reduced. As a result, the surface roughness of the DLC coating formed on the carbide coating is also reduced, so that the wear resistance can be further improved. Become.

  According to the fifth aspect of the present invention, in the wear resistant chain according to any one of the first to fourth aspects, since the hardness of the DLC film increases due to the DLC film being hydrogen-free, Combined with the improved adhesion, the chain wear resistance is improved.

1 is a perspective view of a roller chain that is Embodiment 1 of the present invention. FIG. Sectional drawing of the pin surface of the roller chain of Example 1. FIG. The figure which shows the elongation curve by the acceleration test of the roller chain of Example 1. FIG. The perspective view of the silent chain which is Example 2 of this invention.

  The present invention relates to a wear-resistant chain in which a plurality of link plates are connected to bendable alternately by pins, and the pins have a carbide coating formed on a base material by a diffusion penetration method, and on the carbide coating. If a DLC film is provided on the surface of the pin to provide a wear-resistant chain with a significantly improved wear resistance by coating the surface of the pin with high hardness hydrogen-free DLC with good adhesion, Any particular embodiment may be used.

  In other words, the wear-resistant chain of the present invention may be a chain of any shape as long as a plurality of link plates are connected by a pin so as to be alternately bent. For example, it may be a roller chain or a silent chain.

  An example in which the present invention is applied to a roller chain will be described with reference to FIGS. Here, FIG. 1 is a perspective view of the roller chain of the first embodiment, FIG. 2 is a cross-sectional view of the pin surface of the roller chain of the first embodiment, and FIG. 3 is an acceleration of the roller chain of the first embodiment. It is a figure which shows the elongation curve by a test.

  In the roller chain 10, a pair of bushes 12 having both ends thereof press-fitted into the bushing holes 11 a of the pair of inner plates 11, and both ends of pins 16 pierced into the bushing 12 are disposed on both outer sides of the pair of inner plates 11. The outer plate 14 is press-fitted into the pin hole 14a. And the roller 13 is extrapolated to the bush 12 rotatably.

  Then, a chromium carbide film having a thickness of 15 μm was formed on the base material of the pin 16 by a diffusion permeation method, and a vanadium carbide film having a thickness of 10 μm was formed thereon.

  A powder pack method was used as the diffusion penetration method used in this example. Specifically, carbon and powder in the base material are first obtained by burying a pin (base material) in a powder containing metal (chromium, vanadium) for forming a carbide and heating to a predetermined temperature. The metal inside diffuses to form a film. Since the film formed by interdiffusion exhibits remarkable adhesion to the film formed by other methods, the peeling between the base material and the intermediate layer is less than that of the intermediate layer formed by a method such as the PVD method. Hard to occur.

  For this reason, compared to an intermediate layer formed by a method such as the PVD method, even if the DLC is worn or partially peeled off, the base material is less likely to be worn and effective in maintaining the wear resistance.

  The pin 16 having the carbide film formed on the base material in this way was quenched and tempered, and then polished. After the polishing treatment, a hydrogen-free DLC film having a thickness of 2 μm was formed on the carbide film. As a method for forming the hydrogen-free DLC film, a known PVD method was adopted. A cross-sectional view of the surface of the pin subjected to such surface treatment is shown in FIG.

  As shown in FIG. 2, the pin 16 of the roller chain 10 has a chromium carbide film having a hardness of about 1800 Hv formed on a base material having a hardness of about 600 Hv, and a vanadium carbide film having a hardness of about 2400 Hv formed thereon. A hydrogen-free DLC film having a hardness of 3000 Hv or more is formed thereon. Thus, since the hardness is changed stepwise, the adhesion between the coatings is improved and peeling is unlikely to occur.

  In order to confirm the effect of the wear-resistant chain of Example 1, an acceleration test was performed using a motoring tester under the following conditions, and the chain elongation (%) was measured. As a comparative example, a hydrogen-free DLC film having a thickness of 2 μm, a chromium carbide film having a thickness of 15 μm, and a vanadium carbide film having a thickness of 10 μm were used. The result is shown in FIG.

<Test conditions>
B) Chain: Roller chain with a pitch of 6.35mm b) Number of sprocket teeth: 23 x 46 c) Chain load: 1.5kN
D) Rotational speed: 6500 revolutions / minute e) Test time: 2000 hours

  As can be seen from FIG. 3, it can be seen that the coating layer of Example 1 has improved the wear resistance by a factor of two or more compared to a coating layer consisting only of a hydrogen-free DLC coating, a chromium carbide coating, and a vanadium carbide coating.

  As described above, according to the roller chain of the present embodiment, the hard hydrogen-free DLC film, which has been considered unsuitable as a coating material in terms of adhesion, is used as a pin coating material. As a result, the wear resistance of the roller chain can be dramatically improved.

  Next, an example in which the present invention is applied to a silent chain will be described with reference to FIG. Here, FIG. 4 is a perspective view of the silent chain of the second embodiment.

  Below, the chain comprised as a silent chain which is Example 2 of this invention is demonstrated based on FIG.

  As shown in FIG. 4, the silent chain 20 includes guide links A and inner link plates 22 having a pair of pin holes 22a, a pair of teeth 22b, and a back surface 22c that are alternately displaced in the longitudinal direction of the silent chain 20. The guide plates 24 having the pin holes 24a are arranged in the non-guide rows B, respectively, are arranged on the outermost sides of the guide rows, and the pins 26 are inserted into the respective pin holes 22a of the inner link plate 22. Both ends are fitted and fixed in pin holes 24 a of the guide plate 24.

  Then, the same coating as in Example 1 was applied on the base material of the pin 26. In order to confirm the effect of the wear-resistant chain of Example 2, an acceleration test was performed using a motoring tester under the same conditions as in Example 1, and the chain elongation (%) was measured. Results were obtained.

  As described above, according to the wear-resistant chain of the present invention, the hydrogen-free DLC coating, which has been considered to be unsuitable for the coating material of the chain pin because of its high hardness but adhesion problem, is used as a base. By using a chromium carbide coating and a vanadium carbide coating as the coating layer, the hardness difference between the base material and the hydrogen-free DLC coating has been changed stepwise, and as a result, the peel resistance of the coating has been significantly improved. And the effect is tremendous.

DESCRIPTION OF SYMBOLS 10 ... Roller chain 11 ... Inner plate 12 ... Bush 13 ... Roller 14 ... Outer plate 14a ... Pin hole 16 ... Pin 20 ... Silent chain 22 ... Inside Link plate 22a ... Pin hole 22b ... Teeth 22c ... Back surface 24 ... Guide plate 24a ... Pin hole 26 ... Pin A ... Guide row B ... Non-guide row

Claims (5)

In a wear-resistant chain in which a plurality of link plates are connected by pins so that they can be bent alternately,
A wear-resistant chain, wherein the pin has a carbide coating formed on a base material by a diffusion permeation method and a DLC coating on the carbide coating.   The wear-resistant chain according to claim 1, wherein the carbide coating is a chromium carbide coating or a vanadium carbide coating.   2. The wear-resistant chain according to claim 1, wherein the carbide coating comprises a chromium carbide coating formed on a base material of a pin and a vanadium carbide coating formed on the chromium carbide coating.   The wear-resistant chain according to any one of claims 1 to 3, wherein after the carbide coating is formed, a quenching treatment is performed after a quenching and tempering treatment.   The wear-resistant chain according to any one of claims 1 to 4, wherein the DLC coating is hydrogen-free.

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