JP2005195150A - Rolling device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rolling device which can raise the contact bondability of a hard film, which can maintain a low frictional resistance for a long period and which has an excellent durability. <P>SOLUTION: A cone roller bearing 1 as this rolling device includes a cone roller 4. The large diameter side end face 4c of the cone roller 4 has an annular surface 4f as a rolling slide part in a sliding contact with the collar part 7 of an inner ring 3. A treated region 9 where chemical polishing treatment as an oxide removing treatment is performed, is formed on the entire surface of the cone roller 4. The hard film 11 is formed on the front surface of the region 10 including the annular surface 4f as the rolling slide part of the part of the treated region 9. The hard film 11 preferably includes a diamond-like carbon film. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a rolling device such as a rolling bearing, a ball screw, and a linear motion rolling guide device.

For example, roller bearings are widely used as rolling bearings in automobiles, industrial machines, and the like. Usually, a roller bearing includes a steel inner ring, a steel outer ring, and a roller interposed between the inner and outer rings, and guides the roller with a flange formed on at least one of the inner ring and the outer ring.
However, the roller bearing has a problem that the rotational resistance is large due to the influence of the frictional resistance between the roller and the flange portion.

Therefore, it has been proposed to form a hard coating only on a required portion of the collar portion (see, for example, Patent Document 1).
JP 2001-82466 A

However, the adhesion of the hard film to the base material is poor, and there is a problem in performance that the rotational resistance of the roller bearing increases due to peeling of the hard film, and a problem in durability that the bearing life is reduced. This type of problem is not limited to rolling bearings, but generally exists in rolling devices.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a rolling device that can increase the adhesion of a hard coating, maintain a low frictional resistance over a long period of time, and is excellent in durability.

  For example, when a hard film is formed on a part of a component (friction surface) for the purpose of reducing frictional resistance, an oxide removal process is performed as a pretreatment for the base treatment of the part where the hard film is formed. Since the surface does not become a friction surface, for example, the oxide (black skin) after the heat treatment remains in the portion where the hard film is not formed. As a result of earnest research on the decrease in adhesion of the hard film, the inventor of the present application originally required the formation of a hard film even if a complete oxide removal treatment was performed on the base region of the hard film. It has been found that the adhesion of the hard coating is reduced if a small amount of oxide such as black skin remains in a region that is not applied (for example, a non-friction surface) and is adjacent to the base region.

  The present invention has been made on the basis of the above findings, and in a rolling device including a plurality of components including rolling sliding portions that are in rolling contact or sliding contact with each other, an oxide formed on the surface of at least one component And a hard film formed on the surface of a region to be processed that has been subjected to the removal process and a region that is a part of the region to be processed and includes at least a part of the rolling sliding portion.

  According to this invention, on the surface of the component part, not only the region where the hard coating is formed but also the region adjacent to the region where the hard coating is formed and where the hard coating is not formed is subjected to the oxide removal treatment. Since there exists, the adhesiveness of a hard film can be made high. As a result, peeling of the hard coating can be prevented over a long period, the frictional resistance can be kept low over a long period of time, and the life can be improved.

It is preferable to remove all oxides formed on the surface of the component. More preferably, a region to be treated is provided on the entire surface of the component.
When the oxide removal treatment includes one of shot peening treatment and barrel polishing treatment, the treated region of the component part, for example, oxide on the entire surface is easily and reliably removed by a mechanical removal method. It is preferable in that it can be performed.

When the oxide removal treatment includes a chemical polishing treatment, a region to be treated of a component part, for example, oxide on the entire surface can be easily and reliably removed, and mechanical removal is particularly difficult. It is preferable in that the oxide at the site can be removed reliably.
When the hard film includes a diamond-like carbon film, the lubricity is excellent, so that the frictional resistance can be further reduced. Moreover, the aggression with respect to the counterpart material is small and the durability can be further improved.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a cross-sectional view of a tapered roller bearing as a rolling device according to an embodiment of the present invention.
In the present embodiment, the present rolling device will be described based on the tapered roller bearing 1, but the present invention is not limited to this. For example, as described later, other rolling bearings such as ball bearings, ball screws, A dynamic rolling guide device or the like may be used.

The tapered roller bearing 1 includes an outer ring 2 as a race member, an inner ring 3 as a race member, a plurality of tapered rollers 4 as rolling elements, and a cage 5 as a plurality of components. The plurality of tapered rollers 4 are incorporated in a state of being held by a cage 5 and interposed between the outer ring 2 and the inner ring 3.
The outer ring 2 has a raceway surface 2b as a raceway formed by a conical surface on the inner periphery 2a.

The inner ring 3 includes a raceway surface 3b as a raceway formed on the outer periphery 3a by a conical surface, a first flange 6 extending radially outward from an edge on the small diameter side of the raceway surface 3b, and a large raceway surface 3b. And a second flange portion 7 extending radially outward from the radial edge. The first and second flange portions 6 and 7 each have a guide surface 8 that guides the rolling of the tapered roller 4.
The tapered roller 4 has a truncated cone shape. The tapered roller 4 has a rolling surface 4a having a conical surface, a small diameter side end surface 4b, and a large diameter side end surface 4c. A chamfered portion (not shown) by C chamfering or R chamfering is provided between the end surfaces 4b and 4c and the rolling surface 4a.

The small-diameter side end surface 4 b has an annular portion 4 d that can face the guide surface 8 of the flange portion 6 of the inner ring 3.
The large-diameter side end surface 4c has a circular shallow recess 4e formed at the center when the tapered roller 4 is shaped, and an annular surface 4f surrounding the circular recess 4e.
The cage 5 has a plurality of pockets 5a each having a hole for holding a plurality of tapered rollers 4 respectively.

  The outer ring 2, the inner ring 3, the plurality of tapered rollers 4, and the cage 5 include rolling sliding portions that are in rolling contact or sliding contact with each other. For example, each of the raceway surfaces 2b and 3b of the outer ring 2 and the inner ring 3 and the rolling surface 4a of the tapered roller 4 correspond to rolling sliding portions that are in rolling contact with each other. The guide surface 8 of the first flange portion 6 of the inner ring 3 and the annular surface 4d of the small diameter side end surface 4b of the tapered roller 4 are in sliding contact with each other and correspond to a rolling sliding portion. The guide surface 8 of the second collar portion 7 of the inner ring 3 and the annular surface 4f of the large-diameter end surface 4c of the tapered roller 4 are in sliding contact with each other and correspond to a rolling sliding portion. The rolling surface 4a and end surfaces 4b and 4c of the tapered roller 4 and the peripheral portion 5b of the pocket 5a of the cage 5 are in sliding contact with each other, and correspond to a rolling sliding portion.

FIG. 2 is a perspective view of the tapered roller 4. Please refer to FIG. 1 and FIG.
The feature of the present embodiment is that a region 9 to be treated is formed on the entire surface of the tapered roller 4 as a component part, which has been subjected to a chemical polishing treatment as an oxide removal treatment. Specifically, the to-be-processed area 9 includes a rolling surface 4a, a small diameter side end surface 4b, a large diameter side end surface 4c, and a chamfered portion. A hard film 11 is formed on the surface 10a of a part of the region 10 to be treated, and the region 10 on which the hard film 11 is formed includes at least a part of the annular surface 4f as a rolling sliding part. Specifically, it coincides with the entire area of the annular surface 4f.

In the present embodiment, the case where the hard coating 11 is formed to include the entire annular surface 4f will be described. However, for example, the hard coating 11 may be formed on a part of the annular surface 4f or other than the annular surface 4f. It may be formed on the rolling sliding part.
The tapered roller 4 includes a roller main body 12 that forms a schematic shape of the tapered roller 4 and the above-described hard coating 11 that is formed on a part of the surface of the roller main body 12. The roller body 12 is made of bearing steel and is subjected to carburizing, quenching and tempering treatment as heat treatment. By this heat treatment, an oxide (black skin) may be formed on the surface of the roller body 12. The formed oxide is removed by chemical polishing before the hard coating 11 is formed, and the rolling sliding portion is mechanically polished.

The chemical polishing treatment is performed on the entire surface of the roller body 12 as a production intermediate after the heat treatment in the production process. The chemical polishing treatment is also applied to a portion where the hard coating 11 is not formed in a later step, for example, the above-described depression 4e and chamfered portion.
In the chemical polishing treatment, the roller body 12 after heat treatment is immersed as a part to be treated in a treatment solution such as an acidic solution, and the oxide on the surface thereof is dissolved to remove the oxide from the surface. The treatment liquid is prepared, for example, by mixing a hydrogen fluoride (HF) solution and a hydrogen peroxide (H ₂ O ₂ ) solution with ion-exchanged water so as to have a predetermined molar concentration and diluting it. The whole surface of the part to be treated is exposed and immersed in the treatment liquid to remove the oxide on the whole surface.

As the hard film 11, a diamond-like carbon (hereinafter also referred to as “DLC”) film can be shown.
The DLC film is formed on the surface to be formed with a film thickness of about 1.0 to 5.0 μm, for example, by a sputtering method using carbon as a target, and has a Vickers hardness of about 1000 to 2000 (Hv). It constitutes a hard film having hardness. For example, the surface roughness of the DLC film is controlled to 0.1 μm or less in terms of centerline average roughness (Ra). The DLC film is bonded to the surface to be formed with a predetermined adhesion force (at least 40 N or more, preferably 60 N), and does not peel from the surface to be formed. Further, the DLC film is a film having a low attacking property against the abutting material, a small friction coefficient, an excellent wear resistance, and a slight self-lubricating property, and the guide surface 8 of the flange portion 7 of the inner ring 3. Fretting wear can be suppressed.

In the formation of the DLC film by the sputtering method, the pressure in the deposition chamber into which the introduction gas such as argon gas or hydrocarbon gas is introduced is set to about 10 ⁻³ to 10 (Torr), the discharge voltage is 100 to 2000 (V), and the current is 2 To 10 (A), carbon is vapor-deposited on the above-described surface to be formed, which is the target surface. As a result, a DLC film having the above film thickness, hardness, etc., and having an amorphous structure in which the graphite (SP ² ) structure and the diamond (SP ³ ) structure coexist is formed on the surface to be formed. When this DLC film is formed, the surface portion other than the target surface is masked by a mask member so that carbon does not adhere.

Further, if the DLC film thickness is less than 1.0 μm, the wear resistance is insufficient, and if it exceeds 5.0 μm, not only the cost becomes enormous, but also the internal stress due to the film thickness being too thick increases. Cause peeling. Therefore, the preferable film thickness of the DLC film is 1.0 to 5.0 μm, more preferably 3.0 μm.
Further, when the adhesion force of the DLC film to the surface to be formed is less than 40 N, the DLC film is likely to be peeled off.

Further, if the hardness of the DLC film is less than 1000 in terms of Vickers hardness (Hv), the wear resistance is insufficient, and if it exceeds 2000, internal stress increases and causes peeling.
In addition to the above-described sputtering method, other physical vapor deposition methods (PVD) such as ion plating by ion beam vapor deposition using benzene as a source gas, chemical vapor deposition (CVD), or plasma spraying using a plasma jet, etc. The DLC film may be formed using the thermal spraying method. Further, the adhesion (adhesion strength) to the surface on which the DLC film is formed may be enhanced by finishing the surface to be formed by knurling or the like. However, PVD such as the above-described sputtering method is a film formation method using a physical mechanism, so it is not affected by the material of the surface to be formed, and is higher for the surface to be formed than other film formation methods. Since adhesion can be easily secured, it is optimal for forming a DLC film.

  In the present embodiment, not only the region 10 where the hard coating 11 is formed on the surface of the tapered roller 4, but also the region 9a adjacent to the region 10 where the hard coating 11 is formed and where the hard coating 11 is not formed. Since the polishing treatment is performed, the adhesion of the hard coating 11 can be increased. Furthermore, since all of the oxide formed on the surface of the tapered roller 4 is removed, it is preferable for further improving the adhesion of the hard coating 11. Since the to-be-processed area | region 9 is provided in the whole surface of the tapered roller 4, all the oxides can be removed reliably and it is preferable in order to improve the adhesiveness of the hard film 11 further. As a result, peeling of the hard coating 11 can be prevented over a long period of time, and the friction torque as a frictional resistance can be maintained low over a long period of time, and the life can be improved.

When the oxide removal treatment includes the chemical polishing treatment, the treated region 9 of the tapered roller 4, for example, the oxide on the entire surface can be removed easily and reliably, and mechanical removal is particularly difficult. It is preferable in that the oxide at the site can be removed reliably.
Since the hard coating 11 includes the DLC film, the lubricity is excellent, and therefore the friction torque can be further reduced. Moreover, the aggressiveness with respect to the opposing material, for example, the guide surface 8 of the collar part 7 of the inner ring | wheel 3, is small, and durability can be improved more. This effect can be obtained regardless of the type of DLC film.

In addition, the carburizing abnormal layer can be removed and the fatigue strength can be improved by oxide removal treatment such as chemical polishing treatment. At the same time, by forming the DLC film, it is possible to suppress an increase in the friction torque and improve the seizure resistance and the wear resistance.
Next, another embodiment will be described. In the following description, differences from the above-described embodiment will be mainly described, and description of similar configurations will be omitted. Moreover, in the case of illustration, the same code | symbol is attached | subjected about the same structure.

For example, in the tapered roller 4 of the tapered roller bearing 1 of the present invention, the hard coating 11 is formed so as to include only the annular surface 4f, but this is not limitative. For example, the entire surface of the tapered roller 4 is subjected to chemical polishing, and the hard coating 11 is formed on a surface that is a part of the entire surface and includes at least one of the rolling surface 4a and the two annular surfaces 4d and 4f. There is a case.
Referring to FIG. 1, the tapered roller bearing 1 of the present invention is not limited to the case including the tapered roller 4 having the hard coating 11 formed thereon. For example, the outer ring 2, the inner ring 3, the plurality of tapered rollers 4, When the oxide removal process is performed on the entire surface of at least one component selected from the group including the cage 5 and the hard coating 11 is formed on a part of the surface of the component subjected to the oxide removal process There is. For example, in the outer ring 2, the hard coating 11 may be formed on the surface including the raceway surface 2b. For example, in the inner ring 3, the hard coating 11 may be formed on the surface including at least one of the raceway surface 3b and the two guide surfaces 8. For example, in the cage 5, the hard coating 11 may be formed on the surface including the peripheral edge 5b of the pocket 5a.

  Referring to FIG. 3, the rolling device of the present invention may be a cylindrical roller bearing 13. The cylindrical roller bearing 13 includes, as components, an outer ring 15 as a race member formed with a raceway surface 14, an inner ring 17 as a race member formed with a raceway surface 16, a plurality of cylindrical rollers 18 as rolling elements, and It has a cage 19. Each of the raceway surfaces 14 and 16 as the raceways formed by the cylindrical surfaces of the outer ring 15 and the inner ring 17 and the rolling surface 18a formed by the cylindrical surface of the cylindrical roller 18 correspond to rolling sliding portions that are in rolling contact with each other. The guide surfaces 8 of the flange portions 20 at both ends of the inner ring 17 and the annular surfaces 18c of both end surfaces 18b of the cylindrical roller 18 are in sliding contact with each other and correspond to rolling sliding portions. Further, the rolling surface 18a and the two annular surfaces 18c of the cylindrical roller 18 and the inner peripheral edge 19b of the pocket 19a of the cage 19 are in sliding contact with each other and correspond to a rolling sliding portion.

  In the cylindrical roller bearing 13 of the present invention, an oxide removal treatment is performed on the entire surface of at least one component selected from the group including the outer ring 15, the inner ring 17, the plurality of cylindrical rollers 18, and the cage 19, and the oxide The hard film 11 may be formed on a part of the surface of the component subjected to the removal process. For example, in the outer ring 15, the hard coating 11 may be formed on the inner periphery 15 b as a surface including the raceway surface 14. For example, in the inner ring 17, the hard coating 11 may be formed on the outer periphery 17 b as a surface including at least one of the raceway surface 16 and the two guide surfaces 8. For example, in the cylindrical roller 18, the hard coating 11 may be formed on the surface including at least one of the rolling surface 18a and the annular surfaces 18c at both ends. For example, in the cage 19, the hard coating 11 may be formed on the surface including the peripheral edge portion 19b of the pocket 19a.

Further, the guide surface 8 as a rolling sliding portion of the tapered roller bearing 1 and the cylindrical roller bearing 13 may be provided on a flange provided on at least one of the outer rings 2 and 26 and the inner rings 3 and 17 or omitted. It is also possible.
Referring to FIG. 4, the rolling device of the present invention may be a deep groove type ball bearing 21. The ball bearing 21 includes, as components, an outer ring 22 as a race member, an inner ring 23 as a race member, a plurality of balls 24 as rolling elements, and a cage 25. Each of the raceway grooves 22a and 23a as the races of the outer ring 22 and the inner race 23 and the surface of the ball 24 correspond to a rolling sliding portion that is in rolling contact with each other. The surface of the ball 24 and the inner peripheral edge 25b of the pocket 25a of the cage 25 are in sliding contact with each other and correspond to a rolling sliding portion.

  FIG. 4 illustrates the case where the hard coating 11 is formed on the outer ring 22, the inner ring 23, and the cage 25, but the ball bearing 21 of the present invention includes the outer ring 22, the inner ring 23, and the cage 25. In some cases, the entire surface of at least one component selected from the group is subjected to an oxide removal treatment, and the hard coating 11 is formed on a part of the surface of the component subjected to the oxide removal treatment. For example, in the outer ring 22, the hard coating 11 may be formed on the surface including the raceway groove 22a. For example, in the inner ring 23, the hard coating 11 may be formed on the surface including the raceway groove 23a. For example, in the cage 25, the hard coating 11 may be formed on the surface including the peripheral edge 25b of the pocket 25a. Moreover, although a hard film (not shown) may be formed on the entire surface of the ball 24, the ball 24 in this case is outside the scope of the present invention.

Furthermore, the rolling device of the present invention is not limited to the above-described tapered roller bearing 1, cylindrical roller bearing 13, and ball bearing 21, but can be applied to other known rolling bearings not shown. The present invention can also be applied to rolling devices other than rolling bearings, such as ball screws and linear motion rolling guide devices.
In each said embodiment, an oxide removal process is not limited to a chemical polishing process, For example, a shot peening process, a barrel polishing process, etc. may be sufficient. Any one of chemical polishing, shot peening, barrel polishing, and other known oxide removal processes may be performed, or a plurality of processes may be combined. Furthermore, you may give a superfinishing process after these processes.

  In the case where the oxide removal treatment includes one of shot peening treatment and barrel polishing treatment, it is easy to remove the component, for example, the region 9 to be treated of the tapered roller 4, for example, the oxide on the entire surface, by a mechanical removal method And it is preferable at the point which can remove reliably. The oxide removal process may include both a shot peening process and a barrel polishing process, but if one is included but the other is not included, the processing cost can be reduced.

  In each of the above-described embodiments, the region 9 to be treated for oxide removal is provided on the entire surface of at least one component. It may be provided in a part. However, when the region 9 to be treated is provided on a part of the surface of at least one component, the oxide removal treatment is applied to the part of the surface in a state where the region excluding the part is masked. Will be implemented. For example, in order to form the hard coating 11 on the annular surface 4f of the large-diameter end surface 4c of the tapered roller 4 of the tapered roller bearing 1, the rolling surface 4a and the small-diameter end surface 4b are masked and subjected to oxide removal treatment. When the hard coating 11 is formed by masking the recess 4e of the rolling surface 4a, the small diameter side end surface 4b and the large diameter side end surface 4c, oxide (black skin) remains on the small diameter side end surface 4b. There is no problem.

  In each of the above embodiments, the hard coating may be a DLC film containing tungsten or a DLC film containing silicon. Further, the DLC film may contain metal in addition to tungsten and silicon. Further, a chromium nitride (CrN) film, titanium nitride (TiN) film, or the like may be used as the hard film. Moreover, the hard film may consist of a single film or may have a plurality of films, and preferably includes a DLC film as described above.

  When tungsten or silicon is contained in the DLC film, the adhesion between the DLC film and the surface to be formed can be improved, and as a result, the DLC film can be firmly formed on the surface to be formed. Further, it is possible to reliably prevent the DLC film from peeling from the surface to be formed, and to improve the durability of the DLC film. In addition, since the adhesion between the surface to be formed can be improved, it is not necessary to finish the surface to be formed into a rough surface by knurling or the like.

  In addition, in the DLC film containing tungsten, it is preferable to form the film so that the tungsten component is contained more on the formation surface side than on the film surface side. In other words, by tilting the composition component of the DLC film so that many tungsten components, which are metal atoms, are present on the surface to be formed of a metal material, the adhesion strength of the DLC film to the surface to be formed can be easily improved. It is because it can be made.

The DLC film containing tungsten is, for example, a sputtering method using tungsten carbide as a target in a deposition chamber in which argon gas or hydrocarbon gas as an introduction gas is introduced, or tungsten in a deposition chamber in which hydrocarbon gas is introduced. The pressure in the vapor deposition chamber is about 10 ⁻³ to 10 (Torr), the discharge voltage is 100 to 2000 (V), and the current is 2 to 10 (A). By performing this, a film is formed on the surface to be formed.

  For example, when a film is formed by sputtering using tungsten carbide as a target in an argon gas atmosphere, a tungsten carbide film is formed. This tungsten carbide film is substantially the same as a diamond-like carbon film containing tungsten. It has become a thing. Therefore, the tungsten-containing DLC film includes the tungsten carbide film as described above.

Further, during the formation of the DLC film containing tungsten, the composition component of the DLC film is tilted by appropriately changing the amount of hydrocarbon gas or shielding the surface to be formed with a shutter. Can do. Alternatively, a chromium film may be formed as a base film for the DLC film containing tungsten.
In addition, various design changes can be made within the scope of matters described in the claims.

Below, this invention is demonstrated based on an Example and a comparative example.
[Example]
In the manufacturing process of the tapered roller 4 of the tapered roller bearing 1, the oxide film on the entire surface is removed by chemical polishing, and the hard coating 11 is formed on the annular surface 4f of the large-diameter side end surface 4c. Got. No oxide film (black skin) remains on the surface of the tapered roller 4. Further, as the hard coating 11, a DLC film containing silicon was adopted. The necessary number of tapered rollers 4, the outer ring 2, the inner ring 3, and the cage 5 were incorporated to obtain the tapered roller bearing 1 of the example. The outer ring 2, the inner ring 3 and the cage 5 are not formed with a hard film 11.
[Comparative example]
The difference between the comparative example and the example will be described. That is, in the tapered roller of the comparative example, a hard coating was formed in a state where the oxide film in the hollow portion on the large-diameter side end surface remained, and a tapered roller as a comparative example was obtained. A predetermined number of tapered rollers of a comparative example, an outer ring, an inner ring, and a cage were incorporated to obtain a tapered roller bearing as a comparative example. In other respects, the comparative example and the example are the same.
[test]
The tapered torque bearing 1 of the example and the tapered roller bearing of the comparative example were subjected to the following torque measurement test and seizure test, respectively, and the results were evaluated.
[Torque measurement test]
(Test method) In the test machine, the tapered roller bearing 1 of the example and the tapered roller bearing of the comparative example are assembled as bearings to be tested, an axial load is applied to the bearing to be tested, and the rotation of the outer ring is stopped. The inner ring is continuously rotated at a predetermined rotation speed. When incorporating into the testing machine, a predetermined amount of lubricating oil is supplied to the bearing under test.

In the torque measurement test, the friction torque during rotation of the inner ring of the bearing under test at a predetermined rotational speed at the time when a predetermined time has elapsed after the start of the test is measured. After the measurement, the rotation of the inner ring of the bearing under test is stopped, and the bearing under test is removed and disassembled. The disassembled tapered roller is observed, and the presence or absence of peeling of the DLC film is confirmed.
(Test conditions) The rotation speed was set at three speeds of 10 rotations / minute, 1000 rotations / minute, and 2000 rotations / minute. The axial load was 4000N. ATF (Automatic Transmission Fluid) was used as the lubricating oil.

(Test results) The results of the torque measurement test are shown in FIG. FIG. 5 is a graph showing the relationship between the measured value of the friction torque in the torque measurement test and the rotational speed of the comparative example, and the measured value (Nm) of the friction torque on the vertical axis, and the inner ring on the horizontal axis. The rotation speed (number of rotations per minute) is shown, an example is shown in the white area, and a comparative example is shown in the black area.
Specifically, when the rotational speed is 10 revolutions / minute, the friction torque of the example is 0.6 Nm, the friction torque of the comparative example is 0.72 Nm, and the example is 17% than the comparative example. It was a small value. When the rotational speed was 1000 rpm, the friction torque of the example was 0.25 Nm, the friction torque of the comparative example was 0.29 Nm, and the example was 14% smaller than the comparative example. . When the rotational speed was 2000 rpm, the friction torque of the example was 0.22 Nm, the friction torque of the comparative example was 0.25 Nm, and the example was 12% smaller than the comparative example. .

Thus, the measured value of the friction torque of the Example was a value smaller by 10% or more than the Comparative Example. Thereby, it was confirmed that the friction torque is lower in the example than in the comparative example.
Moreover, from the result of visual observation after the test, it was found that the DLC film of the tapered roller bearing of the example did not peel, whereas the DLC film of the tapered roller bearing of the comparative example peeled. As a result, it was confirmed that the adhesion of the DLC film was higher in the example than in the comparative example.
[Burn-in test]
(Test method) In the test machine, the tapered roller bearing 1 of the embodiment and the tapered roller bearing of the comparative example are assembled as bearings to be tested, an axial load is applied to the bearing to be tested, and the outer ring stops rotating. Are continuously rotated at a predetermined rotational speed. At the time of incorporation in the testing machine, a predetermined amount of lubricating oil is supplied to the bearing under test, and no oil is supplied after the start of the test, and seizure occurs in the bearing under test. When the rotation of the inner ring is locked or a spark is generated, it is determined that seizure has occurred. The elapsed time from the start of the seizure test to the time when seizure occurred was measured, and this elapsed time was obtained as the seizure life.

Three samples S1, S2 and S3 of the tapered roller bearing of the example and three samples S4, S5 and S6 of the tapered roller bearing of the comparative example were tested.
(Test conditions) The rotational speed was 5000 rpm, the axial load was 4000 N, and ATF was used as the lubricating oil.
(Test results) The results of this seizure test are shown in FIG. FIG. 6 is a graph showing the burn-in life of the examples and comparative examples for each of the samples S1 to S6. The vertical axis represents the burn-in life (seconds), and the samples S1, S2, and S3 of the example are shown in the white areas. Samples S4, S5, and S6 of the comparative examples are shown by black portions.

Specifically, the burn-in lifetimes of the samples S1, S2, and S3 of the example were 923 seconds, 875 seconds, and 845 seconds, respectively. In contrast, the burn-in lifetimes of Comparative Samples S4, S5, and S6 were 615 seconds, 588 seconds, and 705 seconds, respectively.
The average value of the seizure life of the samples S1, S2, and S3 of the example is 881 seconds, which is 1.4 times that of the average value of the seizure life of the samples S4, S5, and S6 of the comparative example, which is 636 seconds. It was. Thus, it was confirmed that the example was less likely to be burned than the comparative example, and the durability of the example was high.

  The torque measurement test and the burn-in test are acceleration tests in which severe conditions that are not assumed in normal use conditions are imposed. Therefore, the tapered roller bearing of the present invention does not cause seizure in normal use and has a sufficiently long life.

It is sectional drawing of the tapered roller bearing as a rolling device of one Embodiment of this invention. FIG. 2 is a perspective view of the tapered roller shown in FIG. 1, in which a region to be treated is surrounded by a one-dot chain line, and a region where a hard coating is formed is illustrated as a hatched portion. It is sectional drawing of the cylindrical roller bearing as a rolling device of other embodiment of this invention. It is sectional drawing of the ball bearing as a rolling device of further another embodiment of this invention. It is a graph which shows the relationship between the measured value of the friction torque of the Example and comparative example in a torque measurement test, and a rotational speed. It is a graph which shows the burn-in lifetime of the Example and comparative example in a burn-in test for every sample.

Explanation of symbols

1 Tapered roller bearing (rolling device)
2,15,22 Outer ring (component)
2b, 3b, 14, 16, 22a, 23a Raceway surface (rolling sliding part)
3, 17, 23 Inner ring (component)
4 Tapered rollers (components)
4a, 18a Rolling surface (rolling sliding part)
4d, 4f, 18c Annular surface (rolling sliding part)
5, 19, 25 Cage (component)
5b, 19b, 25b Pocket peripheral part (rolling sliding part)
9 Processed area 10 Area 10a Surface 11 Hard film (diamond-like carbon film)
13 Cylindrical roller bearing (rolling device)
18 Cylindrical rollers (components)
21 Ball bearing (rolling device)
24 balls (components)

Claims (4)

In a rolling device comprising a plurality of components including rolling sliding parts that are in rolling contact or sliding contact with each other,
Formed on the surface of the region to be treated which has been subjected to oxide removal treatment and formed on the surface of at least one component, and the region of the region to be treated that includes at least part of the rolling sliding portion A rolling device comprising a hard coating. The rolling device according to claim 1,
The rolling device characterized in that the oxide removal treatment includes any one of a shot peening treatment and a barrel polishing treatment. The rolling device according to claim 1,
The rolling device characterized in that the oxide removal treatment includes a chemical polishing treatment. In the rolling device according to any one of claims 1 to 3,
A rolling device, wherein the hard coating includes a diamond-like carbon film.

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