JP2005147305A - Retainer for roller bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce abrasion and to prevent early seizure by reducing slide friction resistance of a guide surface of a retainer relative to a planetary gear and an inner peripheral surface of a planetary roller. <P>SOLUTION: In the retainer 7 for the roller bearing 6, a cured layer 7c by heat curing treatment such as cementation is formed on a side of at least guide surface of a matrix material 7a comprising a steel material. A surface of the cured layer 7c is cleaned such that an oxide layer does not exist. A hard film of high hardness such as a DLC film 9 and a CrN film is coated on the cleaned surface. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a roller bearing retainer, and more specifically, in a planetary power transmission device including a planetary gear or a planetary roller, holding the roller bearing interposed between the planetary gear or the planetary roller and its support pin. Related to the vessel.

Planetary power transmission devices used for deceleration and gear shifting, for example, planetary gear type devices, have a structure in which a planetary gear is provided on a carrier via a support pin. While rotating, it revolves around the sun gear on the center side. A roller bearing is interposed between the planetary gear and its support pin (see Patent Document 1).
JP 2000-134869 A

  In the planetary power transmission device, a large centrifugal force acts on the revolving planetary gear. Therefore, in the roller bearing interposed between the planetary gear and its support pin, the lubricating oil flows out and is likely to be poorly lubricated or unlubricated. Under such a lubrication state, the roller bearing retainer is also displaced by the centrifugal force to the inner peripheral surface side of the planetary gear and comes into sliding contact with it. May occur.

  On the other hand, in general rolling bearings for high-speed rotation, a hard film such as a DLC film (diamond-like carbon film) may be formed on the surface of the raceway or rolling element in order to improve wear resistance and seizure resistance. It has been proposed that a similar hard film is formed on the surface of the cage.

  Since the surface of the DLC film has hardness similar to that of diamond, the DLC film has excellent wear resistance and friction resistance is as small as that of molybdenum disulfide and fluororesin, and has been conventionally used as a lubricating material.

  However, the surface of the cage is generally rough, and simply forming a hard film not only provides the required wear resistance and seizure resistance, but also increases the aggressiveness of damaging the surface of the mating member. There's a problem.

  The roller bearing cage according to the present invention has a hardened layer formed by thermosetting treatment on the surface of the base material, the oxide layer is removed from the surface of the hardened layer, and the surface of the hardened layer has a higher hardness than the hardened layer. A hard film is coated.

  Examples of the hard film include a DLC film, a chromium-based thin film such as a CrN film, and a titanium-based thin film such as a TiN film and a TiC film.

  In the cage configured as described above, the guide surface that is coated with the hard film and becomes the outermost surface is in contact with the inner peripheral surface of the outer ring member such as the planetary gear or the outer peripheral surface of the inner ring member such as the support pin. Even if the sliding frictional resistance of the surface is greatly reduced and it is strongly slidably contacted with the mating surface by centrifugal force, etc., there is little wear, no seizure occurs early, and the mating member is damaged. Never give.

  In manufacturing, a hard layer is coated on the clean surface of the hardened layer by removing the oxide layer generated on the surface of the hardened layer as the hardened layer is formed on the surface of the base material by thermosetting. Therefore, the adhesiveness between the base material and the hard film is good, and peeling is difficult to occur.

  As a preferred embodiment of the present invention, the surface of the cured layer is smoothed by polishing, the surface roughness of the smoothed surface is the maximum height Ry3 or less, and the surface roughness of the hard film is 10 points. The average roughness Rz may be 1.0 or less. If the base of the hard film is rough, the surface of the hard film also becomes rough due to the influence. However, in the above configuration, the surface of the hard film depends on the surface roughness of the cured layer that is the base. Smoothness and sliding frictional resistance are reduced.

  As a further preferred embodiment of the present invention, the thickness of the hard film may be 2 μm or more and 3 μm or less. With this film thickness, the coating cost can be kept low, and the effect of the surface condition of the hardened layer that is the base of the hard film hardly appears on the front side of the hard film, and is the outermost surface of the cage. The surface of the hard film can be smoothed and the frictional resistance can be made extremely small.

  As another preferred embodiment of the present invention, the oxygen concentration on the cleaned surface of the cured layer may be 2 ppm or less. With this oxygen concentration, the adhesion between the base material and the hard film is not hindered.

  In the present invention, in addition to the above, an intermediate layer mainly composed of metal may be provided inside the hard film. Examples of the metal component include Cr, W, Ti, Si, Ni, Fe, Co, and the like, and it is preferable that the metal component be a metal contained in the base steel material. When such an intermediate layer is interposed, not only peeling of the hard film is prevented, but also internal stress can be relaxed.

  According to the present invention, not only the hard film is coated with good adhesion on the guide surface side of the cage, but also the guide surface with respect to the inner peripheral surface of the planetary gear or the planetary roller is a hard film with high hardness. Since it is composed of a surface, sliding frictional resistance is low, wear is suppressed, and seizure is prevented.

  The best embodiment of the present invention will be described with reference to FIGS. 1 is a front view of a planetary power transmission device including a roller bearing retainer of the present invention, FIG. 2 is a longitudinal side view of the device of FIG. 1, and FIG. 3 is a half of the roller bearing retainer of the present invention. It is sectional drawing of a part, and has also shown the expanded cross-sectional shape of the surface part of a holder | retainer. FIG. 4 is an enlarged cross-sectional view of a surface portion for illustrating a manufacturing process of the cage of FIG.

  1 and 2, the planetary power transmission device of the present embodiment is a gear type, and includes a sun gear 1, a ring gear 2 disposed at an outer peripheral side of the sun gear 1, and a sun gear 1. And a plurality of planetary gears 3 (four in the illustrated example) provided in mesh with the two gears 1 and 2 and a carrier disposed coaxially on one side of the sun gear 1 in the axial direction. 4, and each planetary gear 3 is rotatably supported by a support pin 5 projecting from the carrier 4. Between the inner peripheral surface of the planetary gear 3 and the outer peripheral surface of the support pin 5, a roller bearing 6 composed of the cage 7 and 8 of the present invention is interposed.

  FIG. 3 shows a portal cage made by pressing and welding as the cage 7 of the roller bearing 6 of the present invention. The retainer 7 has a plurality of pockets 71 for accommodating the rollers 8 along the circumferential direction, and a recess 72 is formed at an axially intermediate position on the inner periphery. There is a recess 73 extending outward in the circumferential direction at an axially intermediate portion of each pocket 71.

  The retainer 7 uses a steel material as a base material 7a, and at least the outer peripheral surface 7b side of the surface portion of the retainer 7 is a hardened layer by thermosetting treatment as shown in part A of FIG. 7c is formed, and a DLC film (diamond-like carbon film) 9 is formed on the surface of the hardened layer 7c as a hard film that is harder than the hardened layer 7c and is thinner than the hardened layer 7c.

  The details will be described with reference to FIG. 3 and FIGS. 4A, 4B, and 4C in the order of the manufacturing process. The base material 7a of the cage 7 is mainly made of carbon steel such as SPCD. Alternatively, carburized steel such as SCM415 is employed. In the machined cage, a bearing steel such as SUJ2 may be used.

  The base material 7a is formed into a predetermined cylindrical shape by pressing and welding, and the surface is polished. A hardened layer 7c is formed on the outer peripheral surface portion of the base material 7a by carburizing, quenching and tempering, and the surface hardness is set to HV450 or more. What is necessary is just the hardness of maximum HV580. Although the depth of the hardened layer 7c is 0.1 mm or more, of course, it is necessary to leave a portion that is not hardened in the core portion of the base material 7a.

  In addition to the above, other thermosetting treatments such as carbonitriding and nitriding may be used for forming the hardened layer 7c.

  By the way, when the hardened layer 7c is formed by thermosetting, the oxide layer 10 is usually formed on the surface of the hardened layer 7c as a deteriorated layer as shown in FIG. If such a layer 10 remains, problems such as easy peeling will occur when a film is formed on the surface.

  Therefore, in this embodiment, after forming the hardened layer 7c, the oxide layer 10 is removed by a mechanical cleaning method such as shot blasting or sand blasting, or a chemical cleaning method such as etching, and FIG. As shown in FIG. 5, the surface of the hardened layer 7c (which is also the outer peripheral surface 7b of the base material 7a) is cleaned so that no oxide is present. As a result of the removal, it suffices if the oxygen concentration at the surface portion of the cured layer 7c is 2 ppm or less.

  Next, the surface 7b of the hardened layer 7c from which the oxide has been removed is polished to smooth the surface 7b of the hardened layer 7c as shown in FIG. The roughness is set to a maximum height Ry3 or less.

  On the cleaned and smooth surface 7b of the hardened layer 7c, a DLC film 9 is coated as a hard film, and the retainer 7 having a surface portion structure as already shown in part A of FIG. can get. The film thickness of the DLC film 9 is set to 2 to 3 μm corresponding to the surface roughness (Ry3 or less) of the hardened layer 7c which is the base. The surface roughness of the DLC film 9 may be in the range of 10-point average roughness Rz 0.1 or more and 1.0 or less.

  Although the DLC film 9 is coated by sputtering, it may be coated by other methods such as a CVD method, a plasma CVD method, an ion beam forming method, an ionized vapor deposition method, and the coating method is not particularly limited. The temperature at the time of coating should be set to 200 ° C. or less, if possible, lower than the tempering temperature of the carburizing process. This is to prevent a degeneration phenomenon such as a decrease in hardness in the hardened layer 7c due to the heat during coating of the DLC film 9.

  In addition to the DLC film 9, examples of the hard film include a chromium-based thin film such as a CrN film and a titanium-based thin film such as a TiN film and a TiC film. The method for forming these films is not particularly limited, but the film thickness and surface roughness are preferably set to the same values as those of the DLC film 9. Moreover, the temperature at the time of coating of CrN film etc. should be 200 degrees C or less if possible, and should be lower than the tempering temperature of carburizing treatment at the highest.

  According to the structure of the said embodiment, the hardening layer 7c by the thermosetting process is formed in the outer peripheral surface 7b side used as the guide surface of the holder | retainer 7, and the DLC film 9 is coated on the surface, The Since the surface is smooth, there is little slip resistance, and even if it is strongly slidably contacted with the inner peripheral surface of the planetary gear 3 that is a member on the outer ring side by centrifugal force or the like, there is little wear and seizure occurs early. Will not cause.

  In the cage 7 having the above-described configuration, the oxide layer 10 is not interposed between the surface 7b of the cured layer 7c and the DLC film 9, and the DLC film 9 is formed on the cleaned surface 7b of the cured layer 7c. Since it is coated, the adhesion between the base material 7a and the DLC film 9 is good, and peeling is unlikely to occur.

  In addition, since the surface 7b of the hardened layer 7c of the base material 7a that is the base of the DLC film 9 is smoothed, the surface of the DLC film 7c is also smoothed accordingly, and the friction coefficient is reduced.

  In the above embodiment, the cage 7 is an outer ring guide type, and a hardened layer 7c and a hard film such as a DLC film 9 or a CrN film are formed on the outer peripheral surface 7b side as a guide surface. The hardened layer 7c and the hard film 9 may be formed on the inner peripheral surface side of the base material 7a, or may be formed on the outer peripheral surface 7b side and the inner peripheral surface side, respectively.

  A hard film such as a DLC film 9 or a CrN film is directly coated on the surface 7b of the hardened layer 7c of the base material 7a, and a metal such as Cr, W, Ti, Si, Ni, Fe, and Co is a main component. An intermediate layer may be provided, and a hard film such as the DLC film 9 may be formed on the outside of the intermediate layer. The metal component of the intermediate layer is preferably a metal contained in the base steel material.

  In the above embodiment, the portal cage 7 made by press and welding is shown. However, the present invention can be applied to other types of cages, for example, M-type cages made by milling. Applicable.

  The roller bearing 6 having the cage 7 of the present invention is not limited to the planetary gear 3, and may be interposed between the planetary roller and its support pin, and generally a cage and roller type roller bearing is provided. Can be used in places.

The front view of the planetary power transmission device containing the holder | retainer of the roller bearing of this invention. FIG. 2 is a longitudinal side view of the apparatus of FIG. 1. It is sectional drawing of the half part of the holder | retainer of the roller bearing of this invention, and has also shown the expanded cross-sectional shape of the surface part of a holder | retainer. The expanded sectional view of the surface part for showing the manufacturing process of the holder | retainer of FIG.

Explanation of symbols

3 planetary gear 5 carrier 6 roller bearing 7 cage 7a base material 7b outer peripheral surface 7c hardened layer 8 roller 9 DLC film (hard film)

Claims (1)

  A cured layer is formed on the surface of the base material by heat curing, the oxide layer is removed from the surface of the cured layer, and a hard film having a hardness higher than that of the cured layer is coated on the surface of the cured layer. A cage for roller bearings.

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