JP2011241007A - Roller chain - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a roller chain with a long life secured without supply of lubricating oil.SOLUTION: The roller chain 1 includes: an inner link 2 constituted by connecting paired inner link plates 21 at their mutually facing both ends with cylindrical bushes 22, respectively; an outer link 3 constituted by connecting paired outer link plates 31 at their mutually facing both ends with pins 32 rotatably inserted through the bushes 22, respectively; and rollers 4 rotatably disposed around outer peripheral surfaces of the bushes 22, respectively. Here, nitriding is performed to both bushes 22 and rollers 4.

Description

 The present invention relates to a roller chain.

 2. Description of the Related Art A heat treatment apparatus (carburizing furnace) that performs a carburizing process on an object to be processed in a high temperature furnace is known. In the furnace of such a heat treatment apparatus, a chain conveyor or the like for conveying an object to be processed is provided, and a roller chain is used for the chain conveyor. The roller chain is connected by an inner link formed by connecting both ends of a pair of inner link plates with a cylindrical bush, and a pin that is rotatably inserted between the ends of a pair of outer link plates through a bush. And an outer link and a roller that is rotatably provided around the outer peripheral surface of the bush. The roller chain is wound around a sprocket or the like and moves along a guide rail extending in one direction.

 As the roller chain moves, the roller rolls on the guide rail, so that the roller slides and rotates with respect to the bush. Further, the bush and the pin slide as the roller chain moves while being wound around the sprocket or the like. Lubricating oil is supplied to the roller chain in order to lubricate between the roller and the bush and between the bush and the pin and reduce wear at the sliding portions. In order to supply the lubricating oil, the lubricating oil is preliminarily applied to an oil bath type supply device in which a part of the moving roller chain is immersed in an oil tank storing the lubricating oil, a roller formed of a sintered material having a gap, or the like. An oil-free roller chain to be included is used (see, for example, Patent Document 1).

JP 2004-286115 A

 By the way, the temperature in the furnace of the heat treatment apparatus is high (for example, 400 ° C.), and the lubricating oil supplied to the roller chain evaporates in the furnace. Therefore, the evaporated lubricating oil adheres to the surface of the object to be processed, which affects the carburizing process, and there is a possibility that the carburizing quality of the object to be processed is deteriorated. Further, the evaporated lubricating oil may be carbonized and solidified in the furnace to generate carbide (coking). For stable operation of the heat treatment apparatus, it is necessary to remove the carbide, and periodic maintenance work for removing the carbide has occurred. Furthermore, when an oil bath type supply device is used to supply lubricating oil to the roller chain, there is a problem that the consumption of lubricating oil due to evaporation increases and the running cost increases.

 On the other hand, when the so-called oil-free operation in which no lubricating oil is supplied to the roller chain is used, the sliding portion between the roller and the bush wears rapidly, and the life of the roller chain is shortened. When the roller chain has a short life, parts replacement work and the like frequently occur, and the running cost increases. Therefore, there is a problem that the current roller chain cannot be oil-free.

 The present invention has been made in consideration of the above points, and an object thereof is to provide a roller chain that can ensure a long life without supplying lubricating oil.

In order to solve the above problems, the present invention employs the following means.
The roller chain according to the present invention is rotatably inserted between the inner link formed by connecting both ends of the pair of inner link plates with a cylindrical bush and the both ends of the pair of outer link plates through the bush. A roller chain comprising outer links each connected by a pin, and a roller that is rotatably provided around the outer peripheral surface of the bush, wherein both the bush and the roller are nitrided Is adopted.
According to the present invention, since both the bush and the roller are nitrided, the surface hardness of the bush and the roller is improved. That is, the hardness at the sliding portion between the bush and the roller is improved.

 Further, the roller chain according to the present invention employs a configuration in which nitriding treatment using the SP-NITE method is performed on both the bush and the roller.

 The roller chain according to the present invention employs a configuration in which both the bush and the roller are made of austenitic stainless steel.

 Further, the roller chain according to the present invention employs a configuration in which the pin is nitrided.

 Further, the roller chain according to the present invention employs a configuration in which the pin is subjected to nitriding treatment using the SP-NITE method.

According to the present invention, the following effects can be obtained.
According to the present invention, the hardness at the sliding portion between the bush and the roller is improved by the nitriding treatment. Therefore, both the bush and the roller have high wear resistance, and a roller chain including such a bush and roller has an effect that a long life can be secured without supplying lubricating oil.

It is the schematic which shows the structure of the roller chain in embodiment of this invention. It is a vertical sectional view showing the positional relationship between the roller chain and the guide rail in the embodiment of the present invention. It is the schematic which shows the general process conditions of the nitriding process using SP-NITE method. It is the schematic which shows the process conditions in embodiment of this invention of the nitriding process using SP-NITE method. It is a perspective view which shows schematic structure of the abrasion test with respect to a test material. It is a graph which shows the result of the abrasion test with respect to a test material.

 Hereinafter, embodiments of the present invention will be described with reference to FIGS. In each drawing used for the following description, the scale of each member is appropriately changed to make each member a recognizable size.

1A and 1B are schematic views showing a configuration of a roller chain 1 in the present embodiment, in which FIG. 1A is a partial cross-sectional plan view, and FIG. 1B is a cross-sectional view taken along line AA in FIG. FIG. 2 is a vertical sectional view showing the positional relationship between the roller chain 1 and the guide rail R in the present embodiment.
The roller chain 1 is used in a heat treatment apparatus (not shown). As an example of the heat treatment apparatus, there is a vacuum carburizing furnace that performs a carburizing process on a workpiece W (see FIG. 2) such as a steel material in a furnace at a high temperature (for example, 400 ° C.) and a vacuum (several hundred Pa). A chain conveyor (not shown) for conveying the workpiece W is provided in the furnace of the heat treatment apparatus, and the chain conveyor includes a roller chain 1. That is, the roller chain 1 is used under a high temperature and vacuum environment.

As shown in FIG. 1, the roller chain 1 includes an inner link 2, an outer link 3, and a roller 4.
The inner link 2 has a configuration in which both ends of a pair of inner link plates 21 are connected by a cylindrical bush 22 respectively. The inner link plate 21 is a plate member extending in one direction. At both ends of the inner link plate 21, through holes that penetrate in the thickness direction are formed. The bush 22 is a member formed in a cylindrical shape, and is fitted and fixed to the through holes at both ends of the inner link plate 21. The pair of inner link plates 21 are connected via a pair of bushes 22 at positions facing each other. The bush 22 is formed using austenitic SUS316 stainless steel.

 The outer link 3 has a configuration in which both ends of the pair of outer link plates 31 are respectively connected by link pins 32 (pins) that are rotatably inserted into the bush 22. The outer link plate 31 is a plate member extending in one direction. At both ends of the outer link plate 31, through-holes that penetrate in the thickness direction are formed. The link pin 32 includes a pin head having a diameter larger than the diameter of the pin body at one end of the pin body formed in a columnar shape. A pair of outer link plates 31 are disposed on both sides of the inner link 2, and the link pins 32 are provided through the through holes and bushes 22 at both ends of the outer link plate 31. At least the link pin 32 is rotatably inserted into the bush 22. A split pin 33 is provided on the opposite side of the pin head of the link pin 32. The split pin 33 is for preventing the link pin 32 from falling off the outer link plate 31. Further, instead of the split pin 33, a crimped portion may be formed on the opposite side of the pin head.

 The roller 4 is for smoothly moving the roller chain 1, and is rotatably provided surrounding the outer peripheral surface of the bush 22. The roller 4 is formed using austenitic SUS316 stainless steel.

 As shown in FIG. 2, the roller chain 1 provided on the chain conveyor of the heat treatment apparatus is installed on a guide rail R extending in one direction (a direction perpendicular to the paper surface). The workpiece W conveyed by the roller chain 1 is supported by the inner link plate 21. The outer peripheral surface of the roller 4 is in contact with the support surface of the guide rail R. That is, the workpiece W is supported by the guide rail R via the inner link plate 21, the bush 22 and the roller 4 in the roller chain 1. In particular, due to the weight of the workpiece W, the outer peripheral surface of the bush 22 is in strong contact with the inner peripheral surface of the roller 4. The roller chain 1 is wound around a sprocket (not shown), and a driving device (not shown) for moving the roller chain 1 is connected to the sprocket.

The roller chain 1 moves along the guide rail R by driving of the driving device, and the workpiece W is conveyed. The roller 4 rolls on the support surface of the guide rail R as the roller chain 1 moves. That is, the roller 4 slides and rotates with respect to the bush 22. Further, the bush 22 and the link pin 32 slide as the roller chain 1 moves while being wound around the sprocket.
The amount of sliding between the roller 4 and the bush 22 is larger than the amount of sliding between the bush 22 and the link pin 32. Furthermore, as described above, the outer peripheral surface of the bush 22 is in strong contact with the inner peripheral surface of the roller 4 due to the weight of the workpiece W. For this reason, when the roller chain 1 reaches the end of its life due to wear of the sliding portion, the end of its life is often reached by wear of the sliding portion between the roller 4 and the bush 22.

 Subsequently, the material and surface treatment of the roller 4 and the bush 22 will be described in more detail. FIG. 3 is a schematic diagram showing general processing conditions for nitriding using the SP-NITE method, which is a method of gas nitriding. FIG. 4 is a schematic diagram showing processing conditions in the present embodiment of nitriding using the SP-NITE method. Note that the nitriding treatment conditions shown in FIGS. 3 and 4 show both the temperature profile indicating the change over time of the treatment temperature for the object to be treated and the supply timing of the atmospheric gas supplied into the treatment furnace. Is.

 As described above, the roller 4 and the bush 22 are formed using austenitic SUS316 stainless steel. This stainless steel is a tempered material that has been subjected to quenching and tempering.

Further, the roller 4 and the bush 22 in the present embodiment are subjected to nitriding using the SP-NITE method.
Nitriding is a surface treatment method in which nitrogen is immersed from the surface of an object to be treated such as a steel material or a titanium alloy to improve the hardness of the surface portion. As the nitriding treatment, there are methods such as a salt bath soft nitriding method, a gas nitriding method, and a plasma nitriding method. In the gas nitriding method, the object to be treated is placed in an atmosphere of ammonia gas (NH ₃ ) or nitrogen gas (N ₂ ), and the object to be treated is heated to a temperature below the austenitizing temperature (800 ° C. to 900 ° C.), In this method, nitrogen is infiltrated into the surface of the object to be processed and cured.

 The SP-NITE method in the present embodiment is a method belonging to the gas nitriding method. For example, when steel is used as the object to be nitrided, the surface of the steel is generally coated with an oxide film (passive film), and the oxide film is removed or activated for proper nitriding. It is necessary to make it. In the SP-NITE method, by introducing CX gas that activates the surface of an object to be treated in an atmosphere of ammonia gas and nitrogen gas, nitriding treatment can be performed with an oxide film, and after treatment, A special nitride layer (so-called SP layer) is formed on the surface of the processed material.

Next, general processing conditions will be described with reference to FIG.
The temperature profile of the nitriding process using the SP-NITE method is divided into a heating period P1, a processing period P2, and a cooling period P3.
The temperature raising period P1 is a period during which the temperature of the object to be processed is increased to the processing temperature for the object to be processed such as the roller 4 and the bush 22. In addition, although 5 hours is illustrated as temperature rising period P1, it is not limited to this, You may adjust suitably according to conditions, such as the material of a to-be-processed object, and the surface hardness of the to-be-processed object calculated | required.
The treatment period P2 is a period during which nitriding treatment is performed on the workpiece. The processing period P2 is exemplified as 14 hours, and the processing temperature is exemplified as 400 ° C., but is not limited to this, depending on conditions such as the material of the object to be processed and the surface hardness of the object to be processed. You may adjust suitably. In addition, as above-mentioned, it is necessary to set process temperature to below the austenitizing temperature (800 degreeC to 900 degreeC) of a to-be-processed object.
The cooling period P3 is a period during which the workpiece at the processing temperature is cooled to room temperature. In addition, although 3 hours are illustrated as the cooling period P3, it is not limited to this, You may adjust suitably according to the material of a to-be-processed object, the grade of the deformation | transformation and damage at the time of cooling, etc.

Moreover, the above-mentioned CX gas, ammonia gas, and nitrogen gas are illustrated as atmospheric gas supplied in a processing furnace.
The supply of the CX gas is started at any point in the temperature raising period P1, and is stopped at any point in the processing period P2. The CX gas supply period indicated by reference numeral P4 in FIG. 3 may be appropriately adjusted according to conditions such as the material of the workpiece and the surface hardness of the workpiece to be obtained. In general, the supply of CX gas is started when the object to be processed has not yet reached the processing temperature, as shown in FIG.
The supply of ammonia gas is started at any point in the temperature raising period P1, and is stopped at any point in the cooling period P3. The supply period of the ammonia gas may be appropriately adjusted according to conditions such as the material of the object to be processed and the surface hardness of the object to be processed. The supply of the ammonia gas is started when the workpiece is heated in the temperature raising period P1, and is stopped when the temperature of the workpiece is lower than the processing temperature in the cooling period P3. It is common.
The supply of nitrogen gas is generally started when the object to be processed starts to be heated in the temperature raising period P1, and is stopped when the temperature of the object to be processed becomes normal temperature and the cooling is completed in the cooling period P3. is there.

Next, with reference to FIG. 4, the process with respect to the roller 4 and the bush 22 which are to-be-processed objects in this embodiment is demonstrated. In this embodiment, the object to be processed is subjected to nitriding treatment under the following processing conditions. However, the present invention is not limited to this, and nitriding treatment under general SP-NITE method processing conditions may be performed. Good.
The temperature raising period P1, the processing period P2, and the cooling period P3 are set to 5 hours, 14 hours, and 3 hours, respectively, and the processing temperature is set to 400 ° C.
The supply of CX gas is started when the workpiece reaches the processing temperature (400 ° C.) (that is, at the end of the temperature raising period P1), and the supply period (P4) is several hours (1 to 5 hours). It is adjusted appropriately within the range. Moreover, ammonia gas is supplied only in the whole period of the processing period P2. That is, the supply of ammonia gas is started from the end of the temperature raising period P1, and the supply thereof is stopped simultaneously with the start of the cooling period P3.

In the temperature raising period P1, the temperature is raised by heating from room temperature to the processing temperature (400 ° C.). In the temperature raising period P1, since the object to be processed is arranged in an atmosphere of nitrogen gas that is an inert gas, changes such as oxidation occurring in the object to be processed can be suppressed.
The temperature of the workpiece reaches the processing temperature, and the processing period P2 starts. In the treatment period P2, the surface of the object to be treated is activated by the introduction of the CX gas, and the ammonia gas that starts to be supplied simultaneously with the CX gas and the nitrogen constituting the nitrogen gas permeate from the surface of the object to be treated. The treatment temperature and treatment time in this embodiment are set to 400 ° C. and 14 hours, respectively, with the aim of improving the corrosion resistance of the workpiece. When nitrogen penetrates, a nitrided layer (a compound layer (so-called white layer) or a diffusion layer) is formed on the surface of the object to be processed, and the surface hardness of the object to be processed is improved. The thickness of the nitride layer formed by the SP-NITE method is 10 μm to several tens of μm. When the object to be processed is SUS316 stainless steel and the SP-NITE method is performed under the conditions of this embodiment, the surface hardness of the object to be processed is about 1000 Hv.

In the cooling period P3, the temperature of the object to be processed is lowered from 400 ° C. to room temperature. In addition, supply of ammonia gas is stopped with the start of the cooling period P3.
This completes the nitriding treatment for the roller 4 and the bush 22 that are the objects to be processed in the present embodiment. After the treatment, the white layer may be removed by polishing or the like.

 By subjecting both the roller 4 and the bush 22 to nitriding treatment using the SP-NITE method, these surface hardnesses are both improved to about 1000 Hv. That is, the hardness at the sliding portion between the roller 4 and the bush 22 is improved. Therefore, both the roller 4 and the bush 22 have high wear resistance, and the roller chain 1 having such a roller 4 and the bush 22 can ensure a long life without supplying lubricating oil. It becomes possible.

Next, the results of experiments carried out with the development of the roller chain 1 that can ensure a long life without supplying lubricating oil will be described. FIG. 5 is a perspective view showing a schematic configuration of a wear test on a test material. FIG. 6 is a graph showing the results of a wear test on the test material.
The present inventors verified a material and a combination of a pair of test materials that can reduce the amount of wear by sliding a pair of test materials selected from a plurality of materials to each other and referring to the amount of wear. As shown in FIG. 5, the configuration of the wear test includes a flat plate member 5 simulating the roller 4 and a columnar member 6 simulating the bush 22. The outer peripheral surface of the columnar member 6 is brought into contact with the plate surface of the flat plate member 5, and a load is applied in the plate thickness direction of the flat plate member 5, while the column is parallel to the plate surface of the flat plate member 5 (direction indicated by reference numeral S). The member 6 was reciprocated, and the volume lost by wear (wear volume, mm ³ ) was measured for each of the flat plate member 5 and the cylindrical member 6. The test conditions of the wear test were as follows: load 19.6 N, sliding speed 10 mm / s, reciprocating stroke 10 mm, test material temperature 400 ° C., sliding time 6 hours (Hr), and test atmosphere was vacuum.

 Table 1 shows combinations of test materials used for the flat plate member 5 simulating the roller 4 and the cylindrical member 6 simulating the bush 22.

As shown in Table 1, S45C carbon steel was selected for both the flat plate member 5 and the columnar member 6 as a conventional material. S45C carbon steel is a material used for a conventional general roller chain 1.
Even if both the conventional roller 4 and the bush 22 are formed using S45C carbon steel, each material is subjected to a tempering process, a carburizing process, etc., and the conventional roller 4 and the bush 22 are They had different hardness. This is because, by making the hardness of the two different, a member having a low hardness is worn and ground by a member having a high hardness in the initial stage of wear, and the contact area between the two is in order to follow the outer shape of the member having a high hardness. This is because the contact pressure is reduced by increasing the value of the pressure, and it has been found that the total wear amount of both can be suppressed in the long term. Therefore, in the conventional roller 4 and the bush 22, both hardness was different from each other.
In addition, the hardness of each S45C carbon steel used for the flat plate member 5 and the cylindrical member 6 shown in Table 1 is the same.

In addition to the conventional material, the amount of wear was measured for four types of combinations from the test material A to the test material D.
“SUS403 (NV nitriding)” shown in Table 1 represents a material obtained by nitriding a martensitic SUS403 stainless steel using an NV nitriding method which is one method of gas nitriding. The NV nitriding method is a method in which an oxide film of a workpiece is replaced with a fluoride film by gas activation treatment with NV gas, and nitrogen is rapidly permeated from the surface of the workpiece while removing the fluoride film with ammonia gas. It is. Even by the NV nitriding method, the surface hardness of the object to be processed can be set to the same surface hardness (1000 Hv or more) as when the SP-NITE method is used.

“SUS440CQT” shown in Table 1 represents a material obtained by subjecting martensitic SUS440C stainless steel to a tempering treatment.
In addition, “SUS403QT” shown in Table 1 represents a material obtained by subjecting martensitic SUS403 stainless steel to a tempering treatment.
In addition, “SUS316 (SP-NITE)” shown in Table 1 represents a material obtained by nitriding austenitic SUS316 stainless steel using the SP-NITE method. Note that the test material D has the same combination as the roller 4 and the bush 22 in the present embodiment.

According to the results of the wear test shown in FIG. 6, nitriding treatment using a SP-NITE method on austenitic SUS316 stainless steel for both the flat plate member 5 imitating the roller 4 and the cylindrical member 6 imitating the bush 22. It can be seen that the wear volume of the combination of the test material D subjected to is the smallest.
According to the conventional knowledge, the wear volume in the combination of the test materials C having different hardnesses should be smaller than the combination of the test materials D in which the hardness of the flat plate member 5 and the cylindrical member 6 is the same. The result is the opposite of conventional knowledge. This means that for materials with a certain hardness or less, the amount of long-term wear can be reduced by making the hardness of the two different, as in the conventional knowledge, but for materials with a certain hardness or more, the hardness of both is the same. It is conceivable that the amount of wear can be reduced by doing so.

Moreover, the combination of the test material A shown in Table 1 is that the flat plate member 5 is formed from a material obtained by nitriding martensitic SUS403 stainless steel using the NV nitriding method, and the cylindrical member 6 is martensitic. SUS440C stainless steel made from a material subjected to a tempering treatment. All of these materials have high hardness, but their hardness is different because of different materials and surface treatments. On the other hand, in the combination of the test materials D in the present embodiment, both the flat plate member 5 and the columnar member 6 are formed of a material obtained by performing nitriding treatment using SP-NITE method on austenitic SUS316 stainless steel. . Here, before the nitriding treatment is performed, the hardness of the austenitic stainless steel is lower than that of the martensitic stainless steel.
However, as shown in FIG. 6, the wear volume in the combination of the test materials D is smaller than the wear volume in the combination of the test materials A. That is, even austenitic stainless steel can be provided with high wear resistance by performing nitriding using the SP-NITE method, and the flat plate member 5 and the cylindrical member 6 (that is, the roller 4 and the bush 22) can be provided. It has been found that wear can be reduced.

 Further, since the martensitic stainless steel has high hardness, it is difficult to machine, and the consumption of the processing tool is severe. Therefore, the labor and cost of manufacturing the roller 4 and the bush 22 tend to increase. On the other hand, since the hardness of the austenitic stainless steel before nitriding is lower than that of martensitic stainless steel, it is possible to reduce the labor and cost of manufacturing the roller 4 and the bush 22.

According to the result of the wear test shown in FIG. 6, the roller 4 and the bush 22 are both provided with such a roller 4 and the bush 22 by subjecting SUS316 stainless steel to nitriding treatment using the SP-NITE method. It has been found that the chain 1 can ensure a long life without supplying lubricating oil.
Therefore, when the roller chain 1 in this embodiment is used for a heat treatment apparatus (carburizing furnace) or the like, it is not necessary to supply lubricating oil for reducing wear. That is, it is possible to achieve complete oil-free, and there are the effects of improving the carburizing quality of the workpiece W and reducing maintenance costs and running costs by preventing the generation of carbides and eliminating the consumption of lubricating oil.

Therefore, according to the present embodiment, the following effects can be obtained.
According to this embodiment, the hardness at the sliding portion between the roller 4 and the bush 22 is improved by nitriding using the SP-NITE method. Therefore, both the roller 4 and the bush 22 have high wear resistance, and the roller chain 1 having such a roller 4 and the bush 22 can ensure a long life without supplying lubricating oil. There is.

 As described above, the preferred embodiments according to the present invention have been described with reference to the accompanying drawings, but the present invention is not limited to the examples. Various shapes, combinations, and the like of the constituent members shown in the above-described examples are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

 For example, in the above embodiment, the nitriding treatment using the SP-NITE method is performed on the roller 4 and the bush 22, but the present invention is not limited to this, and the nitriding treatment is performed using another nitriding method. Also good. For example, the nitriding treatment may be performed by using an NV nitriding method that is a method of gas nitriding. Further, a nitriding method other than the gas nitriding method such as a salt bath soft nitriding method or a plasma nitriding method may be used. In the case of employing the salt bath nitriding method, it is preferable to use the isonite LS method that reduces the environmental load. Such a nitriding method is preferably the same for the roller 4 and the bush 22.

In the above embodiment, the roller 4 and the bush 22 are subjected to nitriding using the SP-NITE method. In addition to this, the link pin 32 sliding with the bush 22 may be subjected to nitriding. Good. The nitriding treatment applied to the link pin 32 is preferably performed using the same method as the nitriding treatment applied to the bush 22.
By nitriding the link pin 32 as well, both the link pin 32 and the bush 22 have high wear resistance, so that wear between the link pin 32 and the bush 22 is reduced. By using such a link pin 32, a long life of the roller chain 1 can be ensured even when the oil is made completely oil-free without supplying lubricating oil to the roller chain 1.
Further, the link pin 32 may be formed of austenitic stainless steel and subjected to nitriding treatment. By using austenitic stainless steel, the labor and cost of processing can be reduced compared to the case of using martensitic stainless steel, for example.

 Moreover, in the said embodiment, although the material used for the roller 4 and the bush 22 is SUS316 stainless steel, it is not limited to this, The material (alloy steel, high alloy steel, titanium which can give nitriding treatment) Alloy). In addition, since the surface hardness after nitriding treatment varies depending on the material used, it is preferable to use a material having a surface hardness after nitriding treatment of 1000 Hv or more.

DESCRIPTION OF SYMBOLS 1 ... Roller chain, 2 ... Inner link, 21 ... Inner link plate, 22 ... Bush, 3 ... Outer link, 31 ... Outer link plate, 32 ... Link pin (pin), 4 ... Roller

Claims (5)

An inner link formed by connecting both ends of a pair of inner link plates with cylindrical bushes, and an end of a pair of outer link plates connected by pins that are rotatably inserted into the bushes. A roller chain comprising an outer link and a roller that is rotatably provided around the outer peripheral surface of the bush,
A roller chain characterized in that nitriding treatment is applied to both the bush and the roller. The roller chain according to claim 1,
A roller chain, wherein the bushing and the roller are both subjected to nitriding using an SP-NITE method. In the roller chain according to claim 1 or 2,
The bush and the roller are both made of austenitic stainless steel. The roller chain according to claim 1,
A roller chain, wherein the pin is subjected to nitriding treatment. The roller chain according to claim 2,
A roller chain, wherein the pin is subjected to a nitriding treatment using an SP-NITE method.

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