JP2004293586A - Wear-resistant chain and manufacturing method for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wear-resistant chain having a high wear-resistant property in an oxidizing atmosphere without causing hydrogen brittleness. <P>SOLUTION: A coated layer composed mainly of chromium carbide and a coated layer composed mainly of a vanadium carbide are alternately laminated into more than three layers on a surface of at least one component forming the chain, and are also laminated so that the layer come in touch with the component is set to be the coated layer composed mainly of the chromium carbide. Consequently, oxidation resistance provided by the chromium carbide and a wear resistance provided by the vanadium carbide synergistically act each other, and the wear-resistant property in an oxidizing atmosphere is remarkably improved. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a chain used as a transport chain, a power transmission chain, a timing chain of an automobile engine, and the like.
[0002]
[Prior art]
As means for improving the wear resistance of a chain that slides flexibly, it is known to apply zinc plating or nickel plating to the surface of a component constituting the chain or to form a hardened layer of a metal carbide such as chromium carbide or vanadium carbide. (For example, see Patent Documents 1 and 2).
[0003]
[Patent Document 1]
Japanese Patent No. 322037 [Patent Document 2]
Japanese Patent No. 3199225
[Problems to be solved by the invention]
However, when zinc plating or nickel plating is applied to the surface of a chain component, when a plating film is formed, hydrogen generated in the pickling or plating process penetrates into the metal structure of the chain component and causes hydrogen embrittlement. However, there has been a problem that the mechanical strength of the component is significantly reduced.
[0005]
In addition, although the hardened layer of a metal carbide such as chromium carbide or vanadium carbide has much better abrasion resistance than zinc-plated or nickel-plated layers, vanadium carbide has insufficient oxidation resistance. It has been pointed out that when used in an oxidizing atmosphere such as in an engine room, sufficient durability cannot be obtained.On the other hand, chromium carbide has been used to respond to the recent demand for higher speed and higher load on chains. Was insufficient in abrasion resistance.
[0006]
Accordingly, an object of the present invention is to provide a wear-resistant chain having high wear resistance even in an oxidizing atmosphere without causing hydrogen embrittlement. Another object of the present invention is to manufacture a wear-resistant chain having high wear resistance even in an oxidizing atmosphere without causing hydrogen embrittlement by a simple method without using a special film forming apparatus. It is an object of the present invention to provide a manufacturing method that can be used.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, a wear-resistant chain according to claim 1 is characterized in that at least one component constituting the chain is provided with a coating layer mainly composed of chromium carbide and a coating layer mainly composed of vanadium carbide. It is constituted by laminating alternately layers or more so that the layer in contact with the component becomes a coating layer mainly composed of chromium carbide.
[0008]
Further, in the method for producing a wear-resistant chain according to claim 2, at least three coating layers mainly composed of chromium carbide and coating layers mainly composed of vanadium carbide are alternately formed on the surface of at least one component constituting the chain. And a method for producing a wear-resistant chain laminated such that a layer in contact with the component is a coating layer mainly composed of chromium carbide, wherein a powder mainly composed of chromium and a powder mainly composed of vanadium are provided. After immersing the component in a processing powder obtained by mixing the above components, the component is maintained at a processing temperature of 650 to 800 ° C. for a certain period of time, and then maintained at a processing temperature of 900 to 1000 ° C. for a certain period of time. And a step of holding the same for a certain time.
[0009]
Here, as the powder mainly containing chromium, for example, commercially available pure chromium powder of about 30 to 200 mesh, pure chromium powder: about 60 to 65% by weight; carbon: about 9% by weight or less; silicon: 8% by weight % Or less; high-carbon ferrochrome powder having a composition of balance iron and inevitable impurities (phosphorus, sulfur, etc.) or chromium: about 65 to 70% by weight; carbon: about 0.1% by weight or less; silicon: 1% by weight Less than or equal to about; powder containing chromium in an amount of more than 50% by weight, such as low-carbon ferrochrome powder having a balance of iron and unavoidable impurities (phosphorus, sulfur, etc.) can be used.
[0010]
On the other hand, examples of the powder containing vanadium as a main component include commercially available pure vanadium powder of about 325 mesh or less, pure vanadium powder: about 75 to 85% by weight, carbon: about 0.2% by weight or less, and silicon: 2% by weight. % Or less; it is possible to use a general-purpose ferrovanadium powder having a balance of iron and inevitable impurities (aluminum, phosphorus, sulfur, etc.).
[0011]
The chains covered by the present invention are all metal chains that bend and slide, such as transmission chains used in engines and the like, transport chains used in logistics transportation, and cable guide chains that protect and guide cables. Contains. Further, in the present invention, as the components forming the coating layer, all the components constituting the chain are targeted.In particular, the coating layer is formed on pins and plates that are liable to be in contact with each other during the operation of the chain and slidably worn. Is most effective.
[0012]
[Action]
Since the present invention has the above-described device configuration, it has the following effects unique to the present invention.
[0013]
According to the wear-resistant chain according to claim 1, at least three coating layers mainly composed of chromium carbide and coating layers mainly composed of vanadium carbide are alternately formed on the surface of at least one component constituting the chain, and Since the layer in contact with the component is laminated so as to be a coating layer mainly composed of chromium carbide, the oxidation resistance of the chromium carbide and the wear resistance of the vanadium carbide act synergistically to form an oxidizing atmosphere. Abrasion resistance inside is remarkably improved. Furthermore, by laminating the coating layer mainly composed of chromium carbide and the coating layer mainly composed of vanadium carbide, the internal stress generated in the coating layer is reduced, and the occurrence of peeling and cracking in the coating layer is suppressed. .
[0014]
According to the method for producing a wear-resistant chain according to claim 2, at least three coating layers mainly composed of chromium carbide and three or more coating layers mainly composed of vanadium carbide are alternately formed on the surface of at least one component constituting the chain. And a method for producing a wear-resistant chain laminated such that a layer in contact with the component is a coating layer mainly composed of chromium carbide, wherein a powder mainly composed of chromium and a powder mainly composed of vanadium are provided. And after immersing the component in the processing powder, maintaining the processing temperature at 650 to 800 ° C. for a certain time, then maintaining the processing temperature at 900 to 1000 ° C. for a certain time, and further processing at 650 to 800 ° C. Chromium or vanadium, which originally contained in the base material, selectively reacts with carbon and chromium or vanadium, and a special film forming device such as a CVD device or PVD device. Without requiring, also, it is possible to form three or more layers of the coating layer without such setup change.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Preferred embodiments of the present invention will be described based on examples. FIG. 1 shows an example in which the present invention is applied to a roller chain 20. In this example, the parts forming the roller chain 20 are liable to be worn by sliding with each other, and the parts forming the roller chain 20 and the chain peripheral parts such as sprockets and tensioner levers used together with the roller chain 20 are slid. A coating layer mainly composed of chromium carbide and a coating mainly composed of vanadium carbide are applied to the outer surface of the pin 25 corresponding to the portion, the inner and outer peripheral surfaces of the bush 22, the inner peripheral surface of the pin hole formed in the plate 24, and the like. Three or more layers are alternately laminated so that a layer in contact with the above-mentioned portion becomes a coating layer mainly composed of chromium carbide.
[0016]
Such a coating layer is formed by the following method. The component for forming the coating layer is immersed in a treatment powder obtained by mixing a powder mainly containing chromium and a powder mainly containing vanadium as described above. Then, after maintaining at a processing temperature of 650 to 800 ° C. for a certain time, the processing temperature is maintained at a processing temperature of 900 to 1000 ° C. for a certain time, and further, at a processing temperature of 650 to 800 ° C. for a certain time.
[0017]
Chromium carbide has a property of forming a film stably in a temperature range of 650 ° C. or more, and vanadium carbide has a property of forming a film in preference to other substances in a temperature range of 900 ° C. or more. Therefore, by immersing the component to form the coating layer on a treatment powder obtained by mixing a powder mainly composed of chromium and a powder mainly composed of vanadium, and performing a heat treatment while changing the temperature as described above, the chromium carbide is formed. A coating layer mainly composed of vanadium carbide is formed on a coating layer mainly composed of chromium, and a coating layer composed of three layers in which a coating layer mainly composed of chromium carbide is further formed thereon can be formed. Note that, by adding an oxide such as Al ₂ O ₃ as a sintering inhibitor to the above-mentioned treated powder or adding a halide such as NH ₄ Cl as a reaction accelerator, for example, The formation of chromium carbide and vanadium carbide can be promoted, and the quality can be stabilized.
[0018]
The thickness of the coating layer can be adjusted by adjusting the processing time in the heat treatment in the range of 10 to 120 minutes. In this example, heat treatment was performed at 700 ° C. for 40 minutes, at 950 ° C. for 60 minutes, and at 700 ° C. for 60 minutes. FIG. 2 shows a cross-sectional distribution of the composition of the coating layer formed as described above. As is apparent from this figure, by performing the above-described heat treatment, three coating layers composed of a coating layer mainly composed of chromium carbide and a coating layer mainly composed of vanadium carbide are formed. In addition, since the coating layer has a boundary region where the composition ratio of the two gradually changes at the boundary between the chromium carbide layer and the vanadium carbide layer, the generation of internal stress between the coating layers is suppressed, and the peeling resistance is improved. An excellent film can be obtained.
[0019]
In order to confirm the effect of the wear-resistant chain of the present invention, a roller chain with a coating layer made of chromium carbide (2 μm) -vanadium carbide (3 μm) -chromium carbide (3 μm) was applied to the outer surface of the roller. A wear test was performed in oil using a motoring tester under the following conditions, and the wear amount of the coating layer was measured. As a comparative example, one having a coating layer of chromium carbide (8 μm) and one having a coating layer of vanadium carbide (8 μm) were used. The result is shown in FIG.
<Test conditions>
B) Chain: roller chain with a pitch of 6.35 mm b) Number of sprocket teeth: 23 x 46 c) Chain load: 1.5 kN
D) Rotation speed: 6500 rotations / minute E) Test time: 2000 hours
As can be seen from FIG. 3, the coating layer of the present invention is slightly inferior in wear resistance as compared with the coating layer composed only of vanadium carbide, but has a 40% reduction in abrasion compared with the coating layer composed only of chromium carbide. To some extent.
[0021]
Next, in order to confirm the effect of the wear-resistant chain of the present invention in an oxidizing atmosphere, a wear test similar to the above was conducted in an oil obtained by adding a small amount of sulfuric acid to a new oil. The result is shown in FIG.
[0022]
As can be seen from FIG. 4, the coating layer of the present invention is slightly inferior in abrasion resistance as compared with the coating layer composed only of chromium carbide, but has an abrasion amount of 20% as compared with the coating layer composed only of vanadium carbide. To some extent.
[0023]
As can be seen from the results of the abrasion test, the coating layer of the present invention has abrasion resistance that can cope with a high-speed and high-load chain in both new oil and an oxidizing atmosphere. In the embodiment, three coating layers composed of a coating layer mainly composed of chromium carbide and a coating layer mainly composed of vanadium carbide are used, but three or more coating layers can be used. In that case, it is preferable that the outermost layer be a coating layer mainly composed of chromium carbide having excellent acid resistance.
[0024]
【The invention's effect】
As described above, the wear-resistant chain and the method for manufacturing the wear-resistant chain according to the present invention have the above-described configuration, and thus have the following effects unique to the present invention.
[0025]
First, according to the wear-resistant chain according to claim 1, at least three parts of a coating layer mainly composed of chromium carbide and a coating layer mainly composed of vanadium carbide are alternately formed on the surface of at least one component constituting the chain. And, since the layer in contact with the component is laminated so as to be a coating layer mainly composed of chromium carbide, the oxidation resistance of chromium carbide and the wear resistance of vanadium carbide act synergistically, The wear resistance in an oxidizing atmosphere is significantly improved. In addition, since the diffusion layer is formed between the coating layers, the stacked coating layers have excellent peeling resistance.
[0026]
According to the method for manufacturing a wear-resistant chain according to claim 2, three coating layers mainly composed of chromium carbide and three coating layers mainly composed of vanadium carbide are formed on the surface of at least one component constituting the chain. A method for producing an abrasion-resistant chain, wherein the layers in contact with the above-mentioned parts alternately, and the layer in contact with the component is a coating layer mainly composed of chromium carbide, wherein the powder mainly composed of chromium and the powder mainly composed of vanadium And after immersing the component in the processing powder, maintaining the processing temperature at 650 to 800 ° C. for a certain time, then maintaining the processing temperature at 900 to 1000 ° C. for a certain time, and further processing at 650 to 800 ° C. It has a process of holding for a certain period of time, so it does not require a special film forming device such as a CVD device or PVD device, and has excellent wear resistance without changing the setup. It can be reproducibly easily form a layer or coating layer. In addition, since the coating layer can be formed without intrusion of hydrogen into the metal structure of the components constituting the chain, the wear-resistant chain manufactured by this method does not cause hydrogen embrittlement.
[Brief description of the drawings]
FIG. 1 is a perspective view of a wear-resistant chain according to Embodiment 1 of the present invention.
FIG. 2 is a diagram showing a composition distribution in a cross section of a coating layer used in the present invention.
FIG. 3 is a view showing the results of a wear test in fresh oil.
FIG. 4 is a diagram showing the results of a wear test in an oxidizing atmosphere.
[Explanation of symbols]
20 ・ ・ ・ Roller chain 21 ・ ・ ・ Inner plate 22 ・ ・ ・ Bush 23 ・ ・ ・ Roller 24 ・ ・ ・ Outer plate 25 ・ ・ ・ Pin

Claims (2)

On the surface of at least one part constituting the chain,
A coating layer mainly composed of chromium carbide and a coating layer mainly composed of vanadium carbide are alternately laminated in three or more layers, and a layer in contact with the component is laminated so as to be a coating layer mainly composed of chromium carbide. Wear-resistant chains. On the surface of at least one part constituting the chain,
A wear-resistant chain in which three or more coating layers mainly composed of chromium carbide and coating layers mainly composed of vanadium carbide are alternately laminated so that the layer in contact with the component is a coating layer mainly composed of chromium carbide. The method of manufacturing
After immersing the component in a processed powder obtained by mixing a powder mainly containing chromium and a powder mainly containing vanadium,
After maintaining at a processing temperature of 650 to 800 ° C. for a certain time,
Holding at a processing temperature of 900 to 1000 ° C. for a certain time,
The method for producing a wear-resistant chain further comprises a step of maintaining the processing temperature at 650 to 800 ° C. for a certain time.

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