JP2005147244A - Manufacturing method for retainer for roller bearing and retainer for roller bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a retainer capable of ensuring required strength even if a hard film is formed. <P>SOLUTION: Cementation heat treatment is applied to a retainer matrix material 7 comprising carbon steel or cemented steel and the hard film having higher hardness than a cementation cured layer is formed on the outer front surface at a lower temperature than the temperature corresponding to annealing temperature of the cementation heat treatment. <P>COPYRIGHT: (C)2005,JPO&amp;NCIPI

Description

  The present invention relates to a roller bearing retainer.

Some roller bearing retainers are interposed between a planetary gear or planetary roller and a support pin in a planetary power transmission device including a planetary gear or planetary roller. Such a planetary power transmission device, for example, a planetary gear type device, has a configuration in which a planetary gear is provided on a carrier through a support pin. During operation, the planetary gear rotates around the support pin while rotating around the support pin. It revolves around the sun gear on the side, and 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, the lubricating oil flows out in the roller bearing interposed between the planetary gear and its support pin, and is likely to be poorly lubricated or unlubricated.

  Under such a lubrication state, the roller bearing cage is also displaced by the centrifugal force to the inner peripheral surface side of the planetary gear and comes into sliding contact, so that wear occurs and seizure occurs early. May occur.

  On the other hand, in general rolling bearings for high-speed rotation, it has been proposed to form a hard film on the surface of the bearing ring or rolling element in order to improve wear resistance and seizure resistance. It is considered to form a DLC film or the like. However, when a general DLC film is formed to increase the wear resistance and seizure resistance, the film forming process temperature is high, which is a thermal factor during the film forming process. It is conceivable that the cage is tempered and the strength of the cage decreases.

  The method for producing a roller bearing cage of the present invention includes a step of forming a hardened layer having a predetermined hardness by carburizing heat treatment on the surface of the cage base material, and a tempering temperature of the carburizing heat treatment below the tempering temperature of the carburized heat treatment after the above step. Forming a hard film having a hardness higher than the above-mentioned hardness at the processing temperature.

  According to the present invention, the surface hardness of the cage base material obtained by performing the carburizing heat treatment is ensured by forming the hard film on the cage base material at a temperature lower than the tempering temperature of the carburizing heat treatment. Thus, a roller bearing cage having the required strength can be obtained.

  As a preferred embodiment of the present invention, the surface hardness of the cage base material after performing the carburizing heat treatment is in the range of HV450-600. Preferably the surface hardness is HV 480-560, more preferably the surface hardness is HV 490-550.

  Further, the hard film is formed at a temperature lower than 300 ° C., preferably 200 ° C. or lower.

  As the hardened layer is formed by carburizing heat treatment, that is, thermosetting treatment, an oxide layer is generally formed on the surface of the hardened layer, and the surface becomes rough. If a hard film is coated on the hardened layer in this state, the hardened layer is easily peeled off, the required wear resistance and seizure resistance are difficult to obtain, and the surface of the mating member may be damaged. Therefore, it is preferable to form a hard film after removing the oxide layer on the surface of the hardened layer. By doing so, the adhesion between the cage base material and the hard film is improved, and the peeling of the hard film is effective. Therefore, it is possible to effectively prevent the counterpart member from being damaged. In addition, by forming a hardened layer having intermediate hardness between the cage base material and the hard film, the strength of the entire cage is increased and good toughness is obtained.

  The cage for roller bearings of the present invention is obtained by subjecting a cage base material made of carbon steel or carburized steel to a carburizing heat treatment, and holding the cage base material at a temperature lower than a temperature corresponding to a tempering temperature of the carburizing heat treatment. It is characterized in that a hard film having a higher hardness than the base metal and rich in lubricity is formed.

Examples of the hard film include chromium thin films such as a DLC film, a CrN film, and a Cr ₂ N film, and titanium thin films such as a TiN film, a TiC film, and a TiCN film. You may comprise a hard film with the kind of these thin films, or the combination of multiple types. However, the film forming temperature is lower than the temperature corresponding to the tempering temperature of the carburizing process.

  The hardness of this type of hard film is much higher than that of the cured layer on the surface of the cage base material, and has a low friction coefficient (μ), so that it has high lubricity. Adjustment of the hardness etc. of these hard films is easily possible.

  In the roller bearing cage having the above-described structure, the hard film is formed on the cage base material at a temperature lower than the temperature corresponding to the tempering temperature of the carburizing heat treatment. After that, the surface hardness of the retainer base material is ensured and has the necessary strength.

  In addition, even when used in poorly lubricated or non-lubricated environments, the surface of the hard film rich in lubricity serves as a guide surface for the mating surface, so it comes into contact with the mating surface with a low coefficient of friction. It is possible to prevent seizure and extend the life.

  In the roller bearing cage of the present invention, the necessary strength can be ensured as a whole while forming a hard film on the surface.

  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 the surface portion for showing the manufacturing process of the cage of FIG. 3, and FIG. 5 is a schematic diagram of the compressive strength test.

  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 is provided. 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 at predetermined intervals in the circumferential direction, and a recess 72 is formed at an axially intermediate position on the inner periphery. A concave portion 73 extending outward in the circumferential direction is formed at an axially intermediate portion of each pocket 71. A column portion 74 is formed between pocket codes 71 adjacent to each other in the circumferential direction, and each column portion 74 is passed between the annular portions 75 on both sides in the axial direction to integrate them.

  The retainer 7 uses a steel material as a base material 7a. Among the surface portions, at least the outer peripheral surface 7b side serving as a guide surface has a thermosetting treatment as shown in an enlarged portion A in FIG. A hardened layer 7c is formed. On the surface of the hardened layer 7c, a DLC (diamond-like carbon) film 9 is formed 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 in the order of the manufacturing process of the cage 7 with reference to FIG. 3 and FIGS. 4 (A), 4 (B), and 4 (C). The base material 7a of the cage 7 is mainly made of carbon steel such as SPCD or carburized steel such as SCM415. 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 of the base material 7a by carburizing, quenching and tempering. The hardness of the surface of the hardened layer 7c is set to HV450 to 600, preferably HV460 to 560. In the case of carburizing, the tempering temperature is set to a temperature of about 300 ° C.

  The depth of the hardened layer 7c is 0.1 mm or more. However, by leaving a portion having the hardness of the raw material (base material 7a) that is not hardened at the core of the base material 7a, the hardness of the outer shell is high and the inside is The cage 7 as a whole is given a predetermined flexibility as a lower hardness. Therefore, the depth of the hardened layer 7c may be 0.5 mm at the maximum. In addition to the above, other thermosetting treatments such as carbonitriding and nitriding may be used for forming the hardened layer 7c.

  When the hardened layer 7c is formed by thermosetting, an oxide layer 11 is usually formed on the surface of the hardened layer 7c as a deteriorated layer as shown in FIG. If such a layer 11 remains, there is a problem that when the layer 11 is formed on the surface, the layer 11 is easily peeled off.

  Therefore, in the present embodiment, after the hardened layer 7c is formed, the oxide layer 11 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 oxide is removed and cleaned on the surface of the hardened layer 7c (also the outer peripheral surface 7b of the base material 7a). As a result of removing the oxide layer 11, it is desirable that the oxygen concentration in the surface portion of the hardened layer 7c is 2 ppm or less.

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

  A DLC film 9 is formed as a hard film on the surface 7b of the cured layer 7c that has been cleaned and smoothed. 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.

  The DLC film 9 is formed by, for example, a sputtering method among PVD processing methods. The temperature at the time of film formation needs to be lower than the tempering temperature 300 ° C., preferably 200 ° C. or less, in the carburizing process. This is to prevent heat generation during the formation of the DLC film 9 from causing a degeneration phenomenon such as a decrease in hardness in the hardened layer 7c.

  In addition, when the film is formed, if the temperature is lower than the tempering temperature of the carburizing process, the film formation method is also particularly suitable for film formation by other methods such as a CVD method, a plasma CVD method, an ion beam forming method, and an ionized vapor deposition method. It doesn't matter.

  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. The film thickness and surface roughness are set to the same values as those of the DLC film 9. Further, the temperature during film formation needs to be lower than 300 ° C., preferably 200 ° C. or lower. This is for the same reason as described above.

  Thus, by carrying out the film formation of the DLC film 9 at a temperature lower than the tempering temperature of 300 ° C. and preventing a degeneration phenomenon such as a decrease in hardness in the hardened layer 7 c, the cage 7 has the compressive strength of the annular portion 75 as For example, it will be manufactured so as to be 500 N or more.

  In the case shown in FIG. 5, this compressive strength test is performed, for example, at 5 mm / min with respect to the outer peripheral surface of the cage 7 with the radial direction on the test table 10 (with the outer peripheral surface placed on the test table 10). The load F is applied from above to vertically downward.

  According to the above configuration, since the DLC film 9 is formed at a temperature lower than the tempering temperature of 300 ° C., the hardened layer 7c is prevented from being deteriorated such as a decrease in hardness. Therefore, the cage 7 can withstand use. Necessary compressive strength is secured.

  Further, the surface of the DLC film 9 becomes a guide surface with respect to the mating surface and comes into contact with the mating surface with a low coefficient of friction, and wear and seizure can be prevented. Since the DLC film 9 has a lubricating action and its surface becomes a guide surface one after another, it is possible to prevent wear and seizure of the base material 7a over a long period of time and to extend the life of the cage 7.

  In the cage 7 of the present invention, the oxide layer 11 generated on the surface of the hardened layer 7c as the hardened layer 7c is formed by the thermosetting treatment is removed, and the DLC film is formed on the clean surface of the hardened layer 7c. 9 is formed, the adhesion between the base material 7a and the DLC film 9 is good, and the DLC film 9 is hardly peeled off.

  In addition, since the surface 7b of the hardened layer 7c of the base material 7a, which is the base of the DLC film 9, is smoothed, the surface of the DLC film 7c is also smoothed accordingly, and the DLC film 9 becomes the guide surface. If this happens, the sliding frictional resistance is small.

  In the above embodiment, the cage 7 is an outer ring guide type, and the hardened layer 7c and the hard film such as the DLC film 9 are formed on the outer peripheral surface 7b side as the guide surface. And the hard film 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.

  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. Schematic diagram of compressive strength test.

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 (8)

Forming a hardened layer of a predetermined hardness by carburizing heat treatment on the surface of the cage base material;
Forming a hard film having a hardness greater than the above hardness at a treatment temperature equal to or lower than the tempering temperature of the carburizing heat treatment on the surface of the cured layer after the step;
A method for manufacturing a roller bearing retainer.   The method for manufacturing a roller bearing retainer according to claim 1, wherein the hardness of the hardened layer is set to HV450 to 600.   The method for manufacturing a roller bearing retainer according to claim 1 or 2, wherein the depth of the hardened layer is set to 0.1 mm or more.   The method for manufacturing a roller bearing cage according to any one of claims 1 to 3, wherein a processing temperature for forming the hard film is set to 300 ° C or lower.   The method for manufacturing a roller bearing retainer according to any one of claims 1 to 4, further comprising a step of removing the oxide layer from the surface of the hardened layer between the two steps. A cage base material on which a hardened layer of a predetermined hardness is formed on the surface;
A hard film formed on the surface of the cage base material and having a hardness higher than the hardness of the cured layer;
A roller bearing retainer.   The roller bearing retainer according to claim 6, wherein the hardened layer is formed by carburizing heat treatment and has a hardness of HV450-600.   The roller bearing retainer according to claim 6 or 7, wherein the hard film is made of any one of a chromium-based thin film, a titanium-based thin film, and a DLC thin film.

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