JP2011190860A - Double-row cylindrical roller bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a double-row cylindrical roller bearing increased in rotational accuracy, durability, and service life by suppressing the lowering of the strength of the resin retainers due to wear during the operation. <P>SOLUTION: This double-row cylindrical roller bearing 1 includes an inner ring 2, an outer ring 3, double-rows of cylindrical rollers 4 rollingly disposed between these both rings, and a set of retainers 10, 10 each holding the cylindrical rollers 4 in each row. Each retainer 10 is a resin injection-molded part which includes an annular part 11 and a plurality of column parts 12 axially projecting from one end surface 11a of the annular part 11 and which defines pockets 13 for holding the cylindrical rollers between the column parts 12, 12 adjacent to each other in the circumferential direction. The set of retainers 10, 10 are disposed while the annular parts 11 abut on each other. At least one of the set of retainers 10, 10 has a molded recessed part 14 in the other end surface 11b of the annular part 11. The recessed part 14 includes a part of a weld part W in the radial direction, particularly an outer diameter side area. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a double row cylindrical roller bearing.

  As is well known, in machine tools such as machining centers, CNC lathes, and milling machines, the main shaft is usually supported rotatably by a bearing, and a cylindrical roller bearing is suitably used as the main shaft support bearing. . This cylindrical roller bearing is roughly divided into a single-row cylindrical roller bearing in which cylindrical rollers are arranged in a single row and a double-row cylindrical roller bearing in which cylindrical rollers are arranged in a double row, which are properly used according to the application and required characteristics. Yes.

  The cylindrical roller bearing includes, as main constituent members, an inner ring and an outer ring, a cylindrical roller disposed so as to be able to roll between the races of both wheels, and a cage in which a pocket for holding the cylindrical roller is defined. Cages are mainly divided into metal and resin. Metal cages have high strength, but their specific gravity is high, making them unsuitable for high-speed rotation applications such as machine tool spindle support. is there. In addition, the metal cage is liable to generate wear powder, and as a result of contamination of the lubricant by the wear powder, there is a problem that the lubrication performance tends to be lowered. Therefore, recently, such a problem hardly occurs and an inexpensive resin cage tends to be used.

  FIG. 10 shows an outline of a known resin cage used for a double row cylindrical roller bearing. As shown in FIGS. 10 (a) and 10 (b), the cage 101 includes an annular portion 102 and a plurality of column portions 103 protruding in the axial direction from one end surface (inner end surface) 102a of the annular portion 102. A so-called comb-shaped cage is defined, and a pocket 104 is defined between the column portions 103 and 103 adjacent to each other in the circumferential direction so as to hold the cylindrical roller in a rollable manner. The retainer 101 is assembled between the inner and outer rings in a so-called back-to-back state in which the other end surfaces (outer end surfaces) 102b of the annular portion 102 are opposed to each other (the annular portion 102 is abutted). For example, see Patent Document 1).

  By the way, the accuracy of the cage, particularly the roundness, greatly affects the bearing performance. As an example of a measure for increasing the roundness of the cage 101 made of resin, it is conceivable to inject and fill molten resin into the cavity from a plurality of gates arranged at equal intervals in the circumferential direction. When the molten resin is injected in this manner, the molten resin flows in the circumferential direction in the cavity and joins between two adjacent gates. Therefore, after the molding is performed in the above-described manner, the released cage 101 is a gate trace 108 formed by dividing the resin remaining in the gate at the time of mold release and a merged trace of the molten resin. Weld lines (weld portions) 107 appear alternately in the circumferential direction.

JP 2004-301232 A

  Although the degree varies depending on the molding conditions and the type of resin used, the weld portion 107 is formed in a raised shape (projection shape) raised from the surface of the annular portion 102 or the column portion 103 as shown in FIG. . Therefore, during operation of a bearing in which the cage 101 injection-molded in the above manner is assembled in a back-to-back state, the weld portion 107 of one cage 101 and the weld portion 107 of the other cage 101 are preferentially slid. Dynamic contact (sliding contact). A high-density and high-strength layer called a skin layer including the formation region of the weld portion 107 is formed on the surface layer portion of the cage 101 that is injection-molded with resin. As described above, the weld portion 107 is formed. When the sliding contact with each other preferentially occurs, the skin layer of the weld portion 107, which is generally the weakest strength portion, wears preferentially, so that the strength of the cage 101 decreases significantly, and the durability life of the bearing is adversely affected. There's a problem.

  For example, if the portion of the weld portion 107 that appears on the outer end surface 102b is removed by machining such as grinding and polishing, the problem of wear of the weld portion 107 during operation can be avoided. However, when machining is performed, the skin layer is thinned or removed in the same manner as when it is slidable and worn during operation, so it is impossible to avoid a decrease in the strength of the cage and a decrease in the durability of the bearing. . In addition, since the number of processing steps increases, the cost merit due to resinization decreases. The various problems described above become more apparent as the number of gates is increased for the purpose of improving the accuracy (particularly roundness) of the cage 101.

  An object of the present invention is to provide a double-row cylindrical roller bearing that is capable of suppressing a decrease in strength of a resin cage due to wear during operation, and that has high rotational accuracy and a long durability life.

  In order to achieve the above object, in the present application, as a first invention, an inner ring and an outer ring, a double-row cylindrical roller disposed so as to be able to roll between both wheels, and each row of the cylindrical rollers are individually held. Each retainer has an annular part and a plurality of pillars projecting in an axial direction from one end face of the annular part, and a cylindrical roller between neighboring pillar parts in the circumferential direction. In a double-row cylindrical roller bearing in which a pair of cages are disposed in a state where the annular portions are butted against each other, at least one of the pair of cages A double-row cylindrical roller bearing having a recess formed on the other end surface of the annular portion, the recess being provided so as to include a partial region in the radial direction of the weld portion. .

  According to such a configuration, in at least one of the cages, the exposure amount of the weld portion on the other end surface of the annular portion serving as the mutual sliding contact surface of the cage is reduced as compared with the conventional product shown in FIG. For this reason, among the skin layers formed on the cage surface layer portion, a case where a pair of conventional products shown in FIG. 10 is used to reduce the cage strength caused by preferential wear of the weld formation region during bearing operation. It can be suppressed compared to. In addition, since the concave portion functions also as a holding portion for a lubricant (for example, grease) filled in the bearing, excellent lubrication performance is stably maintained. Thereby, the progress speed of wear is effectively suppressed.

  In addition, since the concave portion is molded, the skin layer cannot be thinned and the strength of the cage is not reduced as in the case where the concave portion is formed by machining, and the accuracy of the cage (particularly true) Even if the number of gates is increased for the purpose of improving (roundness), the mass production cost does not change. Therefore, it is possible to achieve high accuracy of the cage without causing a special increase in cost, and it is possible to suppress a decrease in strength of the cage. As described above, according to the present invention, it is possible to provide a double row cylindrical roller bearing having high rotational accuracy and a long durability life at low cost.

  Here, the contact surface pressure between the pair of cages tends to be higher in the radially outer (outer diameter side) region due to the centrifugal force acting during operation. In other words, the wear of the cage during operation proceeds most rapidly in the outer diameter side region of the other end face of the annular portion. For this reason, it is desirable to provide the concave portion so as to include at least the radially outer region of the weld portion. Thereby, the early fall of cage | basket intensity | strength can be suppressed effectively. Of course, it is also possible to provide the concave portion so as to include the entire radial region of the weld portion (form the radial groove on the other end surface of the annular portion in the radial direction). It is possible to more effectively suppress a decrease in cage strength due to wear during operation.

  In the above configuration, one of the pair of cages on the side having at least the concave portion including the weld portion further has a concave portion formed to include the gate mark on the other end surface of the annular portion. be able to. In this way, even if the gate mark is formed in a protruding shape on the other end surface of the annular portion, the gate mark is removed due to wear due to sliding contact between the gate marks and a decrease in cage strength due to this. It becomes possible to suppress without processing.

  In the case where a recess including a gate mark is provided, the depth dimension of the recess may be equal to the depth dimension of the recess provided to include the weld part, but the depth dimension of each recess is increased. As the volume reduction amount increases, the required cage strength may not be ensured. As a result of verification by the inventor of the present application, it has been found that the protruding amount of the gate trace is smaller than that of the weld portion. Therefore, when the depth dimension of the recess including the weld portion is h1, and the depth dimension of the recess including the gate mark is h2, the depth dimension of each recess is set so as to satisfy the relational expression of h1> h2. Is desirable. Accordingly, it is possible to effectively suppress a decrease in cage strength due to wear during operation while keeping the volume reduction amount to a necessary minimum.

  By the way, when the cage is a resin injection-molded product, it is necessary to design in consideration of the shape (dimension) change accompanying molding shrinkage. More specifically, in the case of injection molding of resin with a ring portion and a cage having a plurality of column portions projecting from one end surface of the ring portion, the other end surface of the ring portion is as shown in FIG. If it is a flat surface without irregularities, the amount of molding shrinkage (sink amount) in the radial direction intermediate portion of the other end surface of the annular portion tends to increase. When a cage in which such molding shrinkage has occurred is assembled between the inner and outer rings in a state of back-to-back alignment, the contact between the other end surfaces becomes local, so that the contact surface pressure increases, and as a result, wear tends to occur. Such a problem is caused by having a molded annular recess at the outer diameter end and inner diameter end of the other end face of each annular part of each cage. In the direction, the intermediate part can be relaxed by forming it thicker than the both end parts. This is because the height difference in the other end surface of the annular portion after molding shrinkage can be reduced.

  In order to achieve the above object, in the present application, as a second invention, an inner ring and an outer ring, a double row of cylindrical rollers arranged to roll between both wheels, and each row of the cylindrical rollers are individually held. Each retainer has an annular part and a plurality of pillars projecting in an axial direction from one end face of the annular part, and between neighboring pillar parts in the circumferential direction. In a double-row cylindrical roller bearing in which a pair of cages are arranged in a state where the annular portions are abutted with each other, an injection molded product of a resin that defines a pocket for holding the cylindrical rollers. Provided is a double-row cylindrical roller bearing characterized in that at least one has an annular concave portion molded at the outer diameter end portion of the other end face of the annular portion.

  According to such a configuration, as described above, the sliding contact between the cages can be avoided in the outer diameter side region where the contact surface pressure during operation is the highest. Therefore, compared with the case where the cage shown in FIG. 10 is used, a situation where the skin layer, particularly the skin layer in the welded portion forming region is worn by sliding contact with the operation and the strength of the cage is reduced is effectively suppressed. be able to. Since other functions and effects are in accordance with the first invention of the present application described above, the description thereof is omitted here.

  Also in the second invention of the present application, each cage is provided with an annular shape in order to prevent as much as possible the speed of progress of wear during operation due to a decrease in accuracy of the other end face of the annular portion due to molding shrinkage. It is desirable to have a molded annular recess at the outer diameter end and inner diameter end of the other end surface.

  The above-described double-row cylindrical roller bearing according to the present invention can be preferably used, for example, for supporting a spindle of a machine tool.

  As described above, according to the present invention, it is possible to effectively suppress a decrease in strength of the resin cage caused by wear during operation. As a result, it is possible to provide a double row cylindrical roller bearing with high rotational accuracy and long durability life at low cost.

It is a schematic sectional drawing of the double row cylindrical roller bearing which concerns on embodiment of this invention. It is a partial front view of the holder | retainer shown in FIG. 1A is a partially enlarged rear view of the cage shown in FIG. 1, FIG. 1B is a cross-sectional view taken along line AA in FIG. 1A, and FIG. 1C is a cross-sectional view taken along line BB in FIG. Sectional drawing and (d) figure are the principal part enlarged views of (c) figure. (A) A figure is a partial expanded rear view of the holder | retainer which concerns on a modification, (b) A figure is the BB sectional drawing in (a) figure. (A) A figure is a partial expanded rear view of the holder | retainer which concerns on a modification, (b) A figure is CC sectional schematic sectional drawing in (a) figure. It is a measurement result which shows the amount of protrusions of a weld part and a gate trace, respectively, in the sample product of a cage. Both (a) and (b) are partial enlarged rear views of a cage according to a modification. It is a schematic sectional drawing of the double row cylindrical roller bearing which concerns on other embodiment of this invention. (A) is a figure which shows typically the case where the holder | retainer which concerns on a modification is arrange | positioned in the state of back alignment, (b) A figure is a partial expanded rear view of the holder | retainer shown to (a) figure. (A) is a partially enlarged front view of a conventional cage, (b) is a cross-sectional view taken along line AA in (a), and (c) is a cross-sectional view taken along line BB in (a). It is.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  FIG. 1 is a schematic cross-sectional view of a double row cylindrical roller bearing 1 according to an embodiment of the present invention. A double-row cylindrical roller bearing 1 shown in FIG. 1 is incorporated in, for example, a spindle device of a machine tool, and supports a spindle (not shown) that is rotationally driven at high speed with respect to a housing (not shown). The inner ring 2 having double-row inner tracks 2a, 2a, the outer ring 3 having double-row outer tracks 3a, 3a, and the inner track 2a of the inner ring 2 and the outer track 3a of the outer ring 3 are arranged so as to roll freely. The double-row cylindrical rollers 4 and a pair of cages 10 and 10 for individually holding the rows of the cylindrical rollers 4 are provided. A center rod 2b and an outer rod 2c extending outward in the radial direction are respectively provided at the axial central portion and both axial ends of the inner ring 2, and the inner track 2a is provided between the middle rod 2b and the outer rod 2c. Is formed. The cages 10 and 10 are incorporated between the inner and outer rings in a so-called back-to-back state in which the annular portions 11 are butted together. The internal space of the double row cylindrical roller bearing 1 is filled with grease as a lubricant.

  As shown in FIG. 2 and FIGS. 3A and 3B, each cage 10 is projected in an axial direction from an annular portion 11 having an annular shape and one end surface (inner end surface) 11a of the annular portion 11. A plurality (28 in the present embodiment, see FIG. 2) of pillar portions 12 are provided integrally. The column portions 12 are arranged at equal intervals in the circumferential direction, and a pocket 13 is defined between the column portions 12 and 12 adjacent to each other in the circumferential direction so as to hold the cylindrical roller 4 in a rollable manner.

  The cage 10 is an injection-molded product of a resin (molten resin) in which, for example, polyphenylene sulfide (PPS) is used as a base resin, and a filler such as a reinforcing material is appropriately blended therein. Injection molding of the cage 10 is performed by injecting and filling molten resin into the cavity through a plurality of gates arranged in the circumferential direction. In this embodiment, as shown in FIG. Injection molding is performed so that gate traces G (formed by dividing the resin remaining in the gate at the time of mold release) are formed at equal intervals in the direction. Thus, by injecting molten resin into the cavity from a plurality of gates arranged at equal intervals in the circumferential direction, a highly accurate cage 10 having high roundness can be obtained. As shown in FIG. 3 (b), each gate mark G is provided at an intermediate portion in the circumferential direction of the pillar portion 12 every other pillar portion 12. Since the cage 10 is injection-molded so that the gate mark G is formed in such a manner, the molten resin is formed in the middle part in the circumferential direction of each column part 12 where the gate mark G is not formed in the circumferential range. A weld portion W, which is a merged trace, is formed. Each part of the cage 10 is not subjected to machining such as grinding and polishing. Therefore, the weld portion W has a protruding shape that is raised above its periphery (the surface of the cage).

  In the present embodiment, the other end surface (outer end surface) 11b of the annular portion 11 serving as a facing surface (sliding contact surface) of each cage 10 with the mating side, as shown in FIG. A plurality of recesses 14 are provided at intervals. Each recess 14 is provided in the formation region of the weld portion W in the outer end surface 11b of the annular portion 11, and includes the radially outer region of the weld portion W here as shown in FIG. Is provided. Furthermore, each concave portion 14 is formed in a radial groove shape with an outer diameter end portion opened in the outer peripheral surface 11 c of the annular portion 11, and the weld portion W is individually provided in the circumferential range of the concave portion 14. . As shown in FIG. 3D, the depth dimension h <b> 1 of the recess 14 is set to be larger than the protruding amount hw of the weld portion W. Therefore, of the weld portion W appearing on the outer end surface 11b of the annular portion 11, the outer diameter side region located within the range of the concave portion 14 is as if accommodated in the concave portion 14 on the outer end surface 11b. Not exposed. On the other hand, in the weld portion W appearing on the outer end surface 11b of the annular portion 11, the inner diameter side region is exposed on the outer end surface 11b.

  The configuration described above can be obtained by molding the recess 14 at the same time as the cage 10 is injection molded. Specifically, in the molding die of the cage 10, a predetermined position corresponding to the shape of the concave portion 14 is formed at an intermediate position between adjacent gates in the circumferential direction, that is, a position where the molten resin merges to form the weld portion W. What is necessary is just to provide the shaping part of a shape.

  As described above, in the double-row cylindrical roller bearing 1 according to the present invention, each cage 10 has the concave portion 14 formed on the outer end surface 11b of the annular portion 11, and the concave portion 14 has the weld portion W. Are provided so as to include a partial region in the radial direction. According to such a configuration, the exposure amount of the weld portion W on the outer end surface 11b which is a sliding surface of the cages 10 and 10 is reduced as compared with the case where the conventional cage shown in FIG. 10 is used. Can do. Therefore, even when the bearing 1 is in operation, it is possible to prevent the skin layer of the weld portion W, which is the weakest strength portion, from being worn preferentially, thereby reducing the strength of the cage 10. Moreover, since the recessed part 14 functions also as a holding | maintenance part (holding groove) of the grease with which the inside of the bearing 1 is filled, the outstanding lubrication performance is stably maintained. This effectively suppresses the rate of progress of wear caused by the mutual sliding contact during operation.

  The concave portion 14 can be formed by subjecting the cage 10 to injection molding and then performing machining such as grinding. However, if the machining is performed, the skin layer is scraped off, resulting in a decrease in strength. Inevitably, if the number of gates is increased for the purpose of improving the accuracy of the cage 10, the number of processing steps increases accordingly. On the other hand, since the concave portion 14 is molded in the present invention, the mass production cost does not change even if the number of gates is increased, and the skin layer cannot be thinned. Therefore, high accuracy of the cage 10 can be achieved without incurring a special cost increase, and the strength reduction of the cage 10 can be suppressed. As described above, according to the present invention, it is possible to provide the double row cylindrical roller bearing 1 with high rotational accuracy and long durability life at low cost.

  In the present embodiment, the concave portion 14 has an outer diameter end portion opened to the outer peripheral surface 11c of the annular portion 11 so as to include the outer diameter side region of the weld portion W. There is no opening in the inner peripheral surface 11 d of the annular portion 11. In this case, as described above, the inner diameter side region of the weld portion W is exposed on the opposing surface (outer end surface 11b) to the counterpart side, and therefore is retained due to the sliding contact between the weld portions W during operation. It is also considered that the strength of the vessel 10 may decrease. However, during the bearing operation, the cage 10 is deformed to the outer diameter side by the action of centrifugal force, so that the contact surface pressure between the outer end surfaces 11b and 11b becomes higher in the outer diameter side region. In other words, the wear of the cage 10 during operation proceeds most rapidly in the outer diameter side region of the annular portion outer end surface 11b. Therefore, as in the present embodiment, if the recess 14 is provided so as to include the outer diameter side region of the weld portion W, it is possible to effectively suppress an early decrease in the cage strength, which is preferable.

  In order to delay and avoid the wear of the skin layer of the weld portion W, which is the weakest strength portion, as much as possible, the depth dimension h1 of the concave portion 14 is set sufficiently larger than the protruding amount hw of the weld portion W. There is a need. Here, as shown in FIG. 3 (d), the depth dimension h1 of the recess 14 is set to a value obtained by adding a surplus of the dimension hx to the raised amount hw of the weld portion W. The surplus dimension hx is determined in consideration of the maximum wear amount of the outer end face 11b of the annular portion 11 during the bearing operation.

  In the double-row cylindrical roller bearing 1 according to the present embodiment, each of the cages 10 and 10 is a recess that is molded so that the outer end surface 11b of the annular portion 11 includes a partial region in the radial direction of the weld portion W. 14, it is sufficient that the recess 14 is provided on the annular portion outer end surface 11 b of at least one of the cages 10. That is, even with such a configuration, the wear amount of the weld portion W during operation is suppressed as compared with the case where a set of the conventional products shown in FIG. 10 is used.

  As mentioned above, although one Embodiment of this invention was described, embodiment of this invention is not limited to what is shown above. Hereinafter, although other embodiment of this invention is described, there is no change in the structure of the inner ring 2, the outer ring 3, and the cylindrical roller 4, and only the structure of the cage 10 is substantially different from that described above. . Therefore, in the following, the cage 10 is extracted and shown, and the illustration of the double row cylindrical roller bearing 1 is basically omitted.

  For example, as shown in FIGS. 4 (a) and 4 (b), the concave portion 14 of the cage 10 is molded so as to include the entire radial region of the weld portion W, that is, the outer diameter end portion is annular. It may be molded on the outer peripheral surface 11c of the portion 11 and the inner diameter end portion thereof opens on the inner peripheral surface 11d of the annular portion 11. In this case, wear of the skin layer of the weld portion W accompanying operation is further effectively suppressed. Therefore, the life of the double-row cylindrical roller bearing 1 can be further extended.

  Further, at least one of the pair of cages 10 and 10 on the side having the concave portion 14 includes a gate mark G formed on the outer end surface 11b of the annular portion 11 as shown in FIG. Such a recess 15 may be further molded. In the illustrated example, the concave portion 15 including the gate mark G is formed in a radial groove shape on the outer end surface 11b of the annular portion 11 in the same manner as the concave portion 14 including the weld portion W shown in FIG. As described above, if the recess 15 including the gate trace G is further molded, even when the protruding gate trace G is formed on the outer end surface 11b of the annular portion 11, the operation of the bearing is accompanied. Thus, it is possible to suppress a situation in which the gate traces G are slidably contacted with each other and are worn and the cage strength is reduced due to this, without the gate trace G being removed.

  In this case, as shown in FIG. 5B, the depth dimension h2 of the recess 15 including the gate trace G is set smaller than the depth dimension h1 of the recess 14 including the weld W (h1> h2). As a result, the strength reduction of the cage 10 due to wear due to operation is effectively suppressed while the volume reduction amount of the cage 10 is kept to the minimum necessary.

  The reason why the dimensional relationship between the concave portions 14 and 15 is set as described above is based on the measurement result of the sample product shown in FIG. That is, when the inventor of this application injects resin into the cavity through a plurality of gates arranged at equal intervals in the circumferential direction to obtain a sample product of the cage 10 having an annular shape, the sample product is formed in this sample product. The dimensional relationship between the raised amount hg of the gate mark G and the raised amount hw of the weld portion W is because hw> hg as shown in FIG. Furthermore, the protruding amount hg of the gate trace G is less than 50% of the protruding amount hw of the weld portion W. Therefore, in consideration of the safety factor, it is more desirable to set the depth dimension h2 of the recess 15 including the gate mark W so as to further satisfy the relational expression of h2> 0.5h1.

  In addition, at least one of the pair of cages 10 and 10 on the side having the concave portion 14 is molded at the outer diameter end portion of the outer end surface 11b of the annular portion 11 as shown in FIG. It may further have an annular recess 16 formed. According to such a configuration, it is possible to suppress sliding contact in a region where the contact surface pressure between the cages 10 and 10 is high, so that the strength of the cage 10 is further reduced due to wear during operation. Effectively suppressed.

  By the way, when the cage 10 provided with the annular portion 11 and the plurality of column portions 12 protruding from the inner end surface 11a of the annular portion 11 as described above is injection-molded with resin, particularly the outer end surface 11b of the annular portion 11. There is a tendency that the molding shrinkage amount (sink amount) of the intermediate portion in the radial direction becomes large. When such a cage 10 is incorporated in the bearing 1 in a back-to-back state, the contact between the outer end surfaces 11b and 11b becomes local, so that the contact surface pressure increases, and as a result, wear is likely to occur during bearing operation. . As shown in FIG. 7B, such a problem is alleviated by molding an annular recess 16 at the outer diameter end and the inner diameter end of the outer end surface 11b of the annular portion 11 of each cage 10. can do. In other words, the intermediate portion in the radial direction of the annular portion 11 where the amount of molding shrinkage is large is formed thicker than other places. In this way, the height difference in the outer end surface 11b of the annular portion 11 after molding shrinkage can be reduced, so that an excessive increase in contact surface pressure is avoided and effective in suppressing wear.

  FIG. 8 is a schematic cross-sectional view of a double row cylindrical roller bearing 1 according to another embodiment of the present invention. In the double-row cylindrical roller bearing 1 shown in the figure, one of the pair of cages 10 and 10 (left cage 10 in the illustrated example) is molded at the outer diameter end of the annular outer end surface 11b. The annular recess 17 is provided. In this configuration, the outer end surface 11b of the annular portion 11 of each cage 10 is not provided with the concave portion 14 including the weld portion W or the concave portion 15 including the gate mark G as described above. Similarly to the case where the cage 10 shown in FIG. 7A is used, it is possible to avoid sliding contact between the cages 10 in the outer diameter side region where the contact surface pressure is highest. Therefore, a situation in which the skin layer, particularly the skin layer in the welded portion W forming region is worn by sliding contact with the operation and adversely affects the strength of the cage 10 and the durability life of the bearing 1 is effectively suppressed. .

  As shown in FIGS. 9A and 9B, the annular recess 17 shown in FIG. 8 is molded on the outer diameter end and the inner diameter end of the annular outer end surface 11b of the cages 10 and 10. May be. In this way, as described with reference to the embodiment shown in FIG. 7B, the wear progressing speed during operation is increased due to a decrease in accuracy of the annular outer end surface 11b due to molding shrinkage. Can be prevented as much as possible. In this case, the sliding contact between the cages 10 and 10 during the bearing operation is performed by a convex portion provided between the annular concave portions 17 and 17. Therefore, the mutual sliding contact area of the cages 10 and 10 is limited as compared to the case of using the cage 101 in which the outer end surface of the annular portion is configured as a flat surface without unevenness as shown in FIG. Thereby, the mutual contact amount of the weld portion W is reduced, and as a result, the wear amount of the skin layer is also reduced.

  In this case, if the surface area of the outer end surface 11b of the annular portion 11 is 100, the total area of the annular recess 17 is desirably 80 or more. In other words, even if the skin layer of the convex portion is worn by mutual sliding contact between the convex portions provided between the annular concave portions 17 and 17, 80% or more of the skin layer remains on the outer end surface 11b of the annular portion 11. Thus, the dimension of the recess 17 is set. Thereby, the stable bearing performance is ensured over a long period of time.

  Although the embodiment of the present invention has been described above, various modifications can be made to the above-described cage 10. For example, in the embodiment shown in FIGS. 3 to 5 and 7, the depth dimension h <b> 1 of the recess 14 provided so as to include the weld portion W does not necessarily have to be constant over the entire radial direction. It may be different. For example, the depth dimension h1 can be gradually increased from the inner diameter side toward the outer diameter side.

  Although not shown, it is desirable that the cross-sectional shape of the concave portion 14 including the weld portion W and the concave portion 15 including the gate mark G is not a rectangular shape but an arc shape or a combination of arcs. This is because if the cross section of the concave portion 14 or the like is configured by a combination of straight lines, stress concentrates on a portion where the straight lines intersect when a centrifugal force is applied, which may become a breakage starting point of the cage 10.

DESCRIPTION OF SYMBOLS 1 Double row cylindrical roller bearing 2 Inner ring 3 Outer ring 4 Cylindrical roller 10 Cage (Cylinder roller bearing cage)
11 annular portion 11a one end surface (inner end surface)
11b The other end surface (outer end surface)
12 pillar part 13 pocket 14 recessed part 15 recessed part 16 annular recessed part 17 annular recessed part G gate trace W weld part

Claims (8)

The inner ring and the outer ring, a double-row cylindrical roller disposed so as to be able to roll between the two wheels, and a set of cages that individually hold each row of the cylindrical rollers, each cage includes an annular portion, A resin injection-molded product having a plurality of column portions projecting in an axial direction from one end surface of the annular portion, and defining a pocket for holding the cylindrical roller between adjacent column portions in the circumferential direction; and In a double-row cylindrical roller bearing in which a pair of cages are arranged in a state where the annular portions are butted,
At least one of the pair of cages has a recessed portion molded on the other end surface of the annular portion,
The double row cylindrical roller bearing is characterized in that the concave portion is provided so as to include a partial region in the radial direction of the weld portion.   The double row cylindrical roller bearing according to claim 1, wherein the concave portion is provided so as to include at least a radially outer region of the weld portion.   2. One of the pair of cages, wherein one of the sides having at least a concave portion including a weld portion further has a concave portion molded to include a gate mark on the other end surface of the annular portion. Or the double row cylindrical roller bearing of 2.   4. The double-row cylinder according to claim 3, wherein a relational expression of h1> h2 is satisfied, where h1 is a depth dimension of a recess including a weld part and h2 is a depth dimension of a recess including a gate mark. Roller bearing.   The double row according to any one of claims 1 to 4, wherein each retainer has a ring-shaped recess formed at the outer diameter end and the inner diameter end of the other end surface of the annular portion. Cylindrical roller bearing. The inner ring and the outer ring, a double-row cylindrical roller disposed so as to be able to roll between the two wheels, and a set of cages that individually hold each row of the cylindrical rollers, each cage includes an annular portion, A resin injection-molded product having a plurality of column portions projecting in an axial direction from one end surface of the annular portion, and defining a pocket for holding the cylindrical roller between adjacent column portions in the circumferential direction; and In a double-row cylindrical roller bearing in which a pair of cages are arranged in a state where the annular portions are butted,
A double-row cylindrical roller bearing, wherein at least one of the pair of cages has a ring-shaped recess formed at the outer diameter end of the other end face of the annular portion.   7. The double row cylindrical roller bearing according to claim 6, wherein each cage has an annular concave portion formed by molding at an outer diameter end portion and an inner diameter end portion of the other end face of the annular portion.   The double-row cylindrical roller bearing according to any one of claims 1 to 7, which is used for supporting a spindle of a machine tool.

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