JP7660002B2 - Cages and ball bearings - Google Patents

Description

This invention relates to a cage and a ball bearing, and in particular to a one-piece cage with horns, such as a crown cage, that is provided on a ball bearing.

In rolling bearings that require high speed rotation in high temperature environments such as automobiles and machine tools, horn-shaped cages made of synthetic resin are used, which are less aggressive to the rolling elements and have excellent lubricity. On the other hand, horn-shaped cages made of synthetic resin are less resistant to deformation due to centrifugal force compared to metal ones, so when used at high speeds, the cantilever-shaped horns are easily deformed radially outward due to centrifugal force.

In recent years, with the improvement of performance and miniaturization of automobiles and other vehicles, there is a trend for bearings to rotate at even higher speeds, take up less space, and operate at higher temperatures. There is a risk that a cage made of synthetic resin will not be resistant to deformation due to centrifugal force. In other words, if the horns are deformed radially outward by centrifugal force, the area on the tip side and inner diameter side of the horns may come into contact with the rolling elements, hindering the rolling of the rolling elements, or cause abnormal wear or cracks in the cage, or interfere with the inner surface of the outer ring, preventing the bearing from rotating normally without damage. When such concerns exist, cages formed by insert molding, which integrates synthetic resin and metal materials, are used.

The cage disclosed in Patent Document 1 comprises a metal material having a reinforcing ring that is continuous around the entire circumference and a number of reinforcing protrusions that protrude from the reinforcing ring to one side in the axial direction. The reinforcing ring is disposed in the annular portion of the cage and is integrated with the synthetic resin that forms the annular portion. The reinforcing protrusions are disposed in the horns of the cage and are integrated with the synthetic resin that forms the horns. The annular portion of the cage has improved bending rigidity and torsional rigidity against centrifugal force due to the reinforcing ring made of metal, which has higher rigidity than synthetic resin. In particular, the reinforcing ring has an L-shaped cross section around the entire circumference, which enhances the reinforcing effect of the annular portion. Furthermore, the reinforcing protrusions form one side of the L-shaped cross section, which enhances the reinforcing effect of the horns.

The reinforcing protrusions and reinforcing rings each have a through hole. The through holes are filled with synthetic resin, which bonds the synthetic resin and metal material together. Before the metal material is inserted, the metal material is dipped in adhesive, which strengthens the bond between the synthetic resin and metal material.

JP 2020-46069 A (Figures 1 to 4, paragraphs 0002 to 0027)

However, in the cage of Patent Document 1, the reinforcing protrusions made of metal are circumscribed on the synthetic resin that forms the horns and are positioned on the outer diameter of the horns, maximizing the outer diameter of the reinforcing protrusions. This is detrimental to the measures to reduce the mass of the horns (reinforcing protrusions) and reduce the centrifugal force acting on the horns.

In addition, a large through hole is formed in the center of the circumferential width of the reinforcing protrusion to allow for an integral bond with the synthetic resin, and the mass of the reinforcing protrusion is reduced by forming the through hole. However, on the other hand, there is little solid portion where the reinforcing protrusion extends continuously in the axial direction from the reinforcing ring, and the reinforcing efficiency of the reinforcing protrusion at the horn is not good. The reduction in reinforcing efficiency due to the formation of the through hole is also the case with reinforcing rings made of metal.

In addition, the reinforcing protrusions are bonded to the synthetic resin at the periphery of the synthetic resin that forms the horn, but this requires a process of applying adhesive, which makes manufacturing inefficient. If the bond comes apart, the reinforcing effect of the reinforcing protrusions will be lost.

The problem that this invention aims to solve is to efficiently provide reinforcement with metal in a cage in which an annular portion and multiple horns are formed by insert molding that integrates synthetic resin and metal, a reinforcing ring made of metal is disposed in the annular portion, and reinforcing protrusions made of metal are disposed in the horns.

In order to achieve the above object, the present invention provides a cage having an annular portion and a plurality of horns protruding from the annular portion at equal intervals in the circumferential direction to one side in the axial direction, the space between the horns adjacent in the circumferential direction being a pocket for accommodating rolling elements, the annular portion and the plurality of horns being formed by insert molding that integrates a synthetic resin with a metal material, the metal material having a reinforcing ring that is continuous around the entire circumference and a plurality of reinforcing protrusions protruding from the reinforcing ring to one side in the axial direction, the reinforcing ring being disposed in the annular portion, and the plurality of reinforcing protrusions being disposed in the horns, respectively, the reinforcing protrusions having a solid plate portion extending from the reinforcing ring to one side in the axial direction, the solid plate portion extending to one side and the other side in the circumferential direction of the horn, and the synthetic resin covering the solid plate portion from both radial and circumferential sides.

According to the above configuration, the solid plate portion of the reinforcing protrusion extends from the reinforcing ring portion toward one axial side, and also extends to one and the other circumferential sides of the horn, and is covered from both radial and circumferential sides with synthetic resin. This allows the solid plate portion with a wide circumferential width and no through holes to be integrated with the synthetic resin to efficiently reinforce the horn, and ultimately allows efficient reinforcement with metal material.

More specifically, the reinforcing ring has a base plate portion that is solid and continuous around the entire circumference and extends in the radial direction, the base plate portion extends around the inner diameter side and the outer diameter side of the annular portion, and the entire base plate portion is embedded in the synthetic resin. In this way, the base plate portion, which has a wide radial width and no through holes, can be integrated with the synthetic resin to efficiently reinforce the annular portion. In addition, in the circumferential region where the horn and the annular portion are present, the reinforcing protrusion made of metal and the reinforcing ring form an L-shaped cross section without any through holes, which allows particularly efficient reinforcement.

The reinforcing protrusions are preferably continuous with the inner circumference of the reinforcing ring. In this way, the reinforcing protrusions are positioned closer to the central axis (inner diameter side) of the retainer, and centrifugal force acting on the solid plate portion can be reduced, compared to when the reinforcing protrusions are continuous with the outer circumference of the reinforcing ring.

The reinforcing projection may have a rib portion bent from the solid plate portion so as to be discontinuous with the reinforcing ring and to abut against a side surface on one axial side of the reinforcing ring in the axial direction. In this way, the rib portion and the side surface on one axial side of the reinforcing ring abut against each other to resist centrifugal force, and the bending rigidity of the reinforcing projection against centrifugal force can be increased. In addition, since the rib portion is formed by bending from the solid plate portion, it is possible to form the rib portion larger and increase the bending rigidity of the reinforcing projection against centrifugal force, compared to when the rib portion is formed by recessing the continuous portion between the reinforcing ring and the solid plate portion.

The rib portion may be formed on one or both circumferential sides of the reinforcing projection. In this way, the rib portion and the reinforcing ring butt against each other on one or both circumferential sides of the reinforcing projection, so that the bending rigidity of the reinforcing projection against centrifugal force can be further increased.

The reinforcing protrusions are preferably formed to be thinner than the thickness of the base portion of the reinforcing ring. In this way, the mass of the reinforcing protrusions can be reduced, thereby reducing the centrifugal force acting on the reinforcing protrusions.

The rib portion is preferably shaped so that it becomes shorter in the radial direction toward one side in the axial direction. In this way, the mass of the rib portion is suppressed at the tip side of the reinforcing projection without reducing the abutment portion between the rib portion and the reinforcing ring, so that the centrifugal force acting on the reinforcing projection can be further suppressed.

The reinforcing projection has an exposed end that is exposed from the synthetic resin toward one side in the axial direction, and the entire remaining portion of the reinforcing projection, excluding the exposed end, is embedded in the synthetic resin. In this way, insert molding can be performed in which the exposed ends of the multiple reinforcing projections are utilized to place the metal material in the mold, and most of the metal material can be covered with synthetic resin to integrate the metal material and the synthetic resin.

The reinforcing ring may have a flange portion extending in the axial direction. In this way, the flange portion can further increase the rigidity of the reinforcing ring.

The flange portion extends in the other axial direction so as to have an exposed end portion that is exposed from the synthetic resin toward the other axial direction, and the entire remaining portion of the reinforcing ring, excluding the exposed end portion, is embedded in the synthetic resin. In this way, insert molding can be performed in which the exposed end portion of the flange portion is utilized for placing the metal material in the mold, and most of the metal material can be covered with synthetic resin to integrate the metal material and the synthetic resin.

The metal material is preferably formed from cold-rolled steel plate. In this way, the reinforcing rings and reinforcing protrusions can be formed by metal press processing using a mold. Here, cold-rolled steel plate refers to steel that conforms to the "Cold-rolled steel plate and steel strip" of the Japanese Industrial Standards (JIS G3141:2017).

The thickness of the metal material should be 4% to 6% of the diameter of the rolling elements. If the material is cold-rolled steel plate, a thickness of 4% or more of the diameter of the rolling elements will provide the reinforcing effect of the metal material, but a thickness of more than 6% is not preferable as there is a concern that the thickness will be excessive.

The synthetic resin can be at least one of a thermosetting resin and a thermoplastic resin.

A ball bearing comprising the retainer of this invention, an inner ring, an outer ring, and the plurality of rolling elements arranged between the inner ring and the outer ring, has excellent resistance to deformation of the retainer due to centrifugal force, making it suitable for high-speed rotation.

As described above, by adopting the above configuration, the present invention can efficiently provide reinforcement with metal in a retainer in which an annular portion and multiple horns are formed by insert molding that integrates synthetic resin and metal material, a reinforcing ring made of metal is disposed in the annular portion, and reinforcing protrusions made of metal are disposed in the horns.

FIG. 1 is a cross-sectional view showing a ball bearing according to a first embodiment of the present invention. FIG. 1 is a side view showing a cage according to a first embodiment of the present invention, viewed from one axial side; 3 is a cross-sectional view taken along line III-III in FIG. FIG. 1 is a partial perspective view of a metal material according to a first embodiment; A cross-sectional view showing the state before and after deformation of the cage shown in Figure 2 4A and 4B are cross-sectional views showing the state of a cage of a comparative example before and after deformation. FIG. 11 is a partial cross-sectional view showing a cage according to a second embodiment of the present invention. FIG. 11 is a partial perspective view of a metal material according to a second embodiment. FIG. 9A is a schematic cross-sectional view of a workpiece used in the manufacturing process of the metal material shown in FIG. 8 taken along line A-A in FIG. 9B, and FIG. 9B is a side view of the workpiece shown in FIG. 9A from one axial side. FIG. 1A is a schematic diagram showing a cross section of the workpiece in the next process taken along line A-A in FIG. 1B, and FIG. 1B is a side view showing the workpiece in FIG. 1A from one axial side. FIG. 1A is a schematic diagram showing a cross section of the workpiece in the next process taken along line A-A in FIG. 1B, and FIG. 1B is a side view showing the workpiece in FIG. 1A from one axial side.

The following describes a first embodiment of the present invention with reference to the attached drawings, Figures 1 to 6.

The cage 1 shown in Figures 1 to 5 is a bearing component for evenly arranging multiple rolling elements 4 between an inner ring 2 and an outer ring 3 in the circumferential direction. The multiple rolling elements 4 are interposed between an inner raceway 5 formed on the inner ring 2 and an outer raceway 6 formed on the outer ring 3. The rolling elements 4 consist of balls.

In FIG. 1, the central axes (not shown) of the cage 1, inner ring 2, and outer ring 3 are arranged coaxially and correspond to the bearing central axis, which is the design center of rotation of the ball bearing. Hereinafter, the central axis of the cage 1 will be simply referred to as the "central axis."

Here, the axial direction refers to the direction along the central axis. One axial side refers to one axial direction, which is the right side in FIG. 1. The other axial side refers to the opposite direction to the one direction, which is the left side in FIG. 1. The radial direction refers to the direction perpendicular to the central axis. The radially outer side refers to the direction moving away from the central axis in the radial direction, which is the upper side in FIG. 1. The radially inner side refers to the direction approaching the central axis in the radial direction, which is the lower side in FIG. 1. The circumferential direction refers to the direction along the circumference that goes around the central axis. One circumferential side refers to one circumferential direction, which is either left or right in FIG. 2, and the other circumferential side refers to the opposite direction to the one direction.

As shown in Figures 3 to 5, the cage 1 has an annular portion 7 extending in the circumferential direction, and a number of horns 8 protruding from the annular portion 7 in one axial direction at equal intervals in the circumferential direction. The annular portion 7 and the number of horns 8 are formed by insert molding, which integrates a synthetic resin 9 and a metal material 10. The entire cage 1 is formed by insert molding.

The space between adjacent horns 8, 8 in the circumferential direction forms a pocket 11 that houses the rolling element 4.

The cage 1 accommodates the rolling elements 4 in pockets 11 surrounded on three sides by the circumferentially adjacent horns 8, 8 and the annular portion 7. The pockets 11 are spaces that are open radially outward, radially inward, and to one axial side. The same number of pockets 11 are formed as the number N of the multiple horns 8. Each pocket 11 accommodates one rolling element 4. The cage 1 has a shape with N-fold rotational symmetry about its central axis.

The radially outer opening and the radially inner opening of the pocket 11 have a diameter that does not allow the rolling elements 4 to pass radially. The cage 1 is a crown-shaped cage that can accommodate multiple rolling elements 4 arranged between the inner and outer raceways 5, 6 in multiple pockets 11 by elastically deforming the multiple horns 8 to widen the opening on one axial side of the pocket 11 in the circumferential direction.

The outer and inner diameter surfaces of the annular portion 7 are each cylindrical surfaces extending in the circumferential direction. The outer and inner diameter surfaces of the horns 8 are flush with the outer and inner diameter surfaces of the annular portion 7. The outer and inner diameters of the retainer 1 correspond to the diameters of imaginary cylindrical surfaces circumscribing or inscribing the annular portion 7 and the multiple horns 8, respectively. The other axial side of the retainer 1 is made up of the other axial side of the annular portion 7.

The horn portion 8 has a solid base 12 that is axially connected to the annular portion 7, and a pair of claws 13a, 13b that protrude from the solid base 12 to one side in the axial direction.

The solid base 12 is connected in the circumferential direction between the pockets 11, 11 adjacent in the circumferential direction. The pair of claws 13a, 13b consists of a first claw 13a and a second claw 13b that are spaced apart from each other in the circumferential direction. Each claw 13a, 13b is a cantilever beam that protrudes into the air from one axial side of the solid base 12.

A recessed space with depth from the tip of the claw to the other axial direction is formed between the pair of claws 13a, 13b of the horn 8. This reduces the volume of the horn 8 compared to when the recessed space is filled with a resin part. The reduction in the volume of the horn 8 reduces the centrifugal force acting on the horn 8 when the cage 1 rotates, suppressing deformation of the horn 8 due to the centrifugal force.

The surface of the cage 1 that forms the pocket 11 is made of synthetic resin 9. The resin surface that forms the pocket 11 is shaped roughly along an imaginary spherical surface, and includes a contact area that defines the pocket clearance between the cage 1 and the rolling elements 4. The cage 1 and the rolling elements 4 can move relatively freely within the range of the pocket clearance. The center of the imaginary spherical surface coincides with the centers of the rolling elements 4 that are arranged on the pitch circle diameter of the multiple rolling elements 4. The resin surface that forms the pocket 11 is plane-symmetrical with respect to an imaginary plane that includes the centers and central axes of the rolling elements 4 that are arranged on the pitch circle diameter.

By pressing the pair of claws 13a, 13b from the tip in the axial direction against the rolling element 4 that is interposed between the inner and outer raceways 5, 6, each claw 13a, 13b is elastically deformed, widening the opening on one axial side of the pocket 11, and the rolling element 4 enters between the adjacent horns 8, 8.

The metal material 10 has a reinforcing ring 14 that is continuous around the entire circumference, and a number of reinforcing protrusions 15 that protrude from the reinforcing ring 14 to one side in the axial direction. The reinforcing ring 14 is disposed in the annular portion 7. The reinforcing protrusions 15 are each disposed in the horn portion 8.

The metal material 10 is formed from a cold-rolled steel plate such as SPCC or SPCD. The entire metal material 10 can be formed by metal press processing using a die.

The thickness of the metal material 10 is 4% or more and 6% or less of the diameter of the rolling element 4. This thickness is satisfactory for the entire metal material 10. If the thickness is 4% or more, the reinforcing effect of the metal material 10 can be obtained, but if the thickness exceeds 6%, the thickness becomes too large, which is undesirable in terms of embedding in synthetic resin and reducing mass.

The reinforcing ring 14 consists of a base portion 16 that is solidly connected around the entire circumference and extends in the radial direction, and multiple bent portions 17 that connect the base portion 16 and the reinforcing protrusions 15.

The base plate portion 16 does not have a hole that penetrates it in the axial direction. The base plate portion 16 extends around the entire circumference to the inner and outer diameter sides of the annular portion 7. The inner and outer diameter sides of the annular portion 7 are bounded by an imaginary cylindrical surface that bisects the difference between the inner and outer diameters of the annular portion 7 in the radial direction.

The end of the inner diameter side of the substrate portion 16 is located on the inner diameter side of the annular portion 7, close to the inner diameter surface of the annular portion 7 (i.e., close to the inner diameter surface of the annular portion 7 with respect to an imaginary cylindrical surface that further bisects the difference between the aforementioned boundary and the inner diameter of the annular portion 7 in the radial direction). Similarly, the end of the outer diameter side of the substrate portion 16 is located on the outer diameter side of the annular portion 7, close to the outer diameter surface of the annular portion 7.

The bent portion 17 is a bent portion that has been plastically deformed by bending the portion that is to become the reinforcing protrusion 15 toward one side in the axial direction.

The inner circumference of the reinforcing ring 14 is made of a circular plate edge of the base plate portion 16 that is continuous around the entire circumference. Therefore, the inner diameter of the reinforcing ring 14 is constant around the entire circumference. The inner diameter of the reinforcing ring 14 corresponds to the inner diameter of the metal material 10.

The outer periphery of the reinforcing ring 14 is made up of a plurality of bent portions 17 and a plurality of arc-shaped plate edges extending in an arc concentric with the circular plate edge between adjacent bent portions 17, 17 in the circumferential direction. The outer diameter of the reinforcing ring 14 corresponds to the diameter of an imaginary circle circumscribing the plurality of bent portions 17. The outer diameter of the reinforcing ring 14 corresponds to the outer diameter of the metal material 10.

The multiple reinforcing protrusions 15 are each continuous with the outer periphery of the reinforcing ring 14 at the bent portion 17. The circumferential pitch of the multiple reinforcing protrusions 15 corresponds to the pitch of the horn portion 8. The diameter of an imaginary circle circumscribing the multiple reinforcing protrusions 15 is equal to the outer diameter of the reinforcing ring 14.

The reinforcing projection 15 is made of a solid plate portion that extends from the bent portion 17 of the reinforcing ring 14 to one side in the axial direction. The reinforcing projection 15 (solid plate portion) extends to one side and the other side in the circumferential direction of the horn portion 8. The one side and the other side in the circumferential direction of the horn portion 8 are bounded by an imaginary plane that bisects the horn portion 8 in the circumferential direction and includes the central axis.

The end of the reinforcing piece 15 on one circumferential side is located close to the nearest pocket 11 on that circumferential side of the horn 8 (i.e., close to the pocket 11 on an imaginary plane that further bisects the area between the aforementioned boundary and the nearest pocket 11 in the circumferential direction and includes the central axis). Similarly, the end of the reinforcing piece 15 on the other circumferential side is located close to the nearest pocket 11 on the other circumferential side of the horn 8.

The circumferential width of the reinforcing protrusion 15 is set constant over the entire length of the reinforcing protrusion 15.

The entire reinforcing ring 14 is embedded in the synthetic resin 9 that forms the annular portion 7, and has no exposed portion. Therefore, the entire base portion 16 is embedded in the synthetic resin 9. The entire surface of the annular portion 7 is made up of the inner diameter surface, the outer diameter surface, the side surface on the other axial direction, and the pocket bottom that defines the portion of the pocket 11 on the other axial direction, and is formed from the synthetic resin 9.

The solid base 12 of the horn section 8 is made of synthetic resin 9 and a reinforcing protrusion 15. Each of the claws 13a, 13b is made only of synthetic resin 9. The synthetic resin 9 covers the reinforcing protrusion 15 (solid plate section) on both radial sides (inner and outer sides) and circumferential sides (one side and the other side).

The reinforcing projection 15 has an exposed end 18 that is exposed from the synthetic resin 9 toward one axial side. The exposed end 18 is located at one axial end of the solid base 12, and is a component of the side surface of the retainer 1 on one axial side. The entire remainder of the reinforcing projection 15, excluding the exposed end 18, is embedded in the synthetic resin 9.

The synthetic resin 9 may be any resin that can be injection molded, such as engineering plastics, and may be at least one of thermoplastic resin and thermosetting resin, and may be either crystalline resin or non-crystalline resin. The synthetic resin may be primarily composed of thermosetting resin or thermoplastic resin, with other thermosetting resins, thermoplastic resins, rubber, glass fiber (GF), carbon fiber, carbon black, graphite, etc. added as appropriate.

There is no adhesive layer between the metal material 10 and the synthetic resin 9. In insert molding, since almost the entire metal material 10 is embedded in the synthetic resin 9, it is possible to strongly integrate the metal material 10 and the synthetic resin 9 without bonding the synthetic resin 9 and the metal material 10 with an adhesive. Therefore, it is possible to omit the process of applying adhesive to the metal material 10 before inserting the metal material 10 into a mold (not shown). When inserting the metal material 10 into a mold, the metal material 10 can be arranged so that the central axis of the metal material 10 faces the axial direction by contacting the exposed end 18 with the mold at three or more locations equally spaced in the circumferential direction. In addition, as a means for preventing the metal material 10 from moving improperly due to the flow of the synthetic resin 9 injected into the mold, for example, a means for magnetically attracting the exposed end 18 to the mold by installing an electromagnet in the mold can be adopted.

The deformation of the cage 1 due to centrifugal force at a specified bearing rotation speed was calculated by CAE analysis for the cage 1 in which the synthetic resin 9 was formed using polyamide 66 (PA66) + GF and the metal material 10 was formed using SPCC equivalent to 5% of the rolling elements 4. In addition, a comparison example in which the metal material 10 was omitted from the cage 1 and replaced with the polyamide 66 (PA66) + GF was also calculated by numerical analysis. The specified bearing rotation speed was 5000 to 10000 rpm, and calculations were performed for every 1000 rpm (6 conditions). Considering the value of dmn (pitch circle diameter of the rolling elements 4 x bearing rotation speed per minute) in the ball bearing used as the base model for the CAE analysis, a bearing rotation speed of 5000 rpm corresponds to a dmn value of 240,000, and a bearing rotation speed of 10,000 rpm corresponds to a dmn value of 540,000.

In an analysis example of the retainer 1, the state of deformation at 10,000 rpm is shown in Figure 5, and in a comparative example, the state of deformation at 10,000 rpm is shown in Figure 6. In Figures 5 and 6, the solid lines show the shape of the retainer at 10,000 rpm, and the dashed lines show the shape of the retainer when the bearing is stopped. Points A and A' shown in Figures 5 and 6 are the corners where the tips of the claws 13b and 13b' of the horns 8 and 8' intersect with the inner diameter surface.

In the analysis example of the cage 1, the displacement amount is the difference between the radial position of point A when the bearing is stopped and the radial position of point A at a specified bearing rotation speed. In the comparative example, the displacement amount is the difference between the radial position of point A' when the bearing is stopped and the radial position of point A' at a specified bearing rotation speed.

In the analysis results of the analysis example and the comparative example of the retainer 1, it was confirmed that the displacement δ of the analysis example of the retainer 1 was smaller than the displacement δ' of the comparative example under all speed conditions from 5,000 to 10,000 rpm. In particular, at 10,000 rpm, the displacement δ of the analysis example of the retainer 1 was 29% smaller than the displacement δ' of the comparative example. From these analysis results, it was confirmed that the metal material 10 of the retainer 1 shown in Figures 1 to 4 has a reinforcing effect against centrifugal force.

As described above, the cage 1 is made of a solid plate portion in which the reinforcing protrusion 15 extends from the reinforcing ring 14 to one side in the axial direction, and the reinforcing protrusion (solid plate portion) 15 extends to one and the other circumferential sides of the horn portion 8. The synthetic resin 9 covers the reinforcing protrusion 15 from both radial and circumferential sides. This allows the circumscribed circle diameter of the reinforcing protrusion 15 to be smaller than that of the horn portion 8, compared to when the reinforcing protrusion 15 is the outer diameter surface of the horn portion 8. Also, compared to when a through hole is formed in the reinforcing protrusion 15 to integrally bond it to the synthetic resin 9, the reinforcing protrusion 15 and the synthetic resin 9 can be strongly integrated without using adhesive, and the reinforcing protrusion 15 can efficiently reinforce the horn portion 8 by widening the circumferential direction of the solid portion extending axially in a continuous manner from the reinforcing ring 14, thereby allowing efficient reinforcement by the metal material 10.

In addition, the retainer 1 has a base plate portion 16 in which the reinforcing ring 14 is solidly connected around the entire circumference and extends in the radial direction, and the base plate portion 16 extends around the inner and outer diameter sides of the annular portion 7 around the entire circumference. The entire base plate portion 16 is filled with synthetic resin 9, so that compared to forming a through hole in the reinforcing ring 14 to integrally bond it to the synthetic resin 9, the reinforcing ring 14 and the synthetic resin 9 are strongly integrated without using adhesive, and the solid portion of the reinforcing ring 14 that extends in a continuous manner around the entire circumference is made wider in the radial direction to efficiently reinforce the annular portion 7. This makes the reinforcement by the metal material 10 more efficient, and in the circumferential region where the horn portion 8 and the annular portion 7 are present, the reinforcing protrusion 15 and the reinforcing ring 14 form an L-shaped cross section without a through hole, so that reinforcement can be particularly efficient.

In addition, the retainer 1 has an exposed end 18 where the reinforcing protrusions 15 are exposed from the synthetic resin 9 toward one axial side, and the entire remaining part of the reinforcing protrusions 15 except for the exposed end 18 is embedded in the synthetic resin 9. This allows insert molding to be performed in which the exposed end 18 of the multiple reinforcing protrusions 15 is utilized for positioning the metal material 10 in a mold, and most of the metal material 10 can be covered with the synthetic resin 9 to integrate the metal material 10 and the synthetic resin 9.

In addition, because the metal material 10 of the retainer 1 is made of cold-rolled steel plate, the reinforcing ring 14 and reinforcing protrusion 15 can be easily formed by metal press processing.

In addition, the thickness of the metal material 10 of the retainer 1 is 4% to 6% of the diameter of the rolling elements 4, so that the reinforcing effect of the metal material 10 can be obtained while avoiding excessive thickness.

In addition, the ball bearing according to the first embodiment has excellent resistance to deformation of the cage 1 due to centrifugal force, making it suitable for high-speed rotation.

In this way, the retainer 1 is made of a metal plate having higher rigidity than the synthetic resin 9, and is provided with the reinforcing ring 14, which is formed with a wide solid portion without through holes as described above, and the metal material 10, which reinforces the annular portion 7 and the horn portion 8 with a plurality of reinforcing protrusions 15, so that the rigidity of the retainer 1, particularly the ring rigidity and torsional rigidity of the horn portion 8, can be improved. As a result, even when the ball bearing is operated at high speed in a high-temperature environment, deformation of the retainer 1 due to centrifugal force or heat, and vibration deformation of the retainer 1 due to disturbances can be suppressed, and the claws 13a, 13b of the horn portion 8 can be prevented from interfering with the inner peripheral surface of the outer ring 3, which would damage the retainer 1, and the performance of the ball bearing and, ultimately, the performance of the rotating machine device can be maintained in a good condition. In addition, in the unlikely event that a crack or the like occurs in the retainer 1, the inserted metal material 10 can maintain the shape of the retainer and retard the progress of the crack.

The second embodiment of the present invention will be described with reference to Figures 7 to 11. Note that the following will only describe the differences from the first embodiment.

As shown in Figures 7 and 8, the metal material 20 according to the second embodiment has a reinforcing ring 21 and a reinforcing protrusion 22 whose shapes have been changed from those of the first embodiment.

The reinforcing ring 21 has a flange portion 24 that extends axially from the base portion 23. The flange portion 24 is formed by bending the outer periphery of the base portion 23 toward the other axial side.

The reinforcing piece 22 consists of a solid plate portion 25 that is continuous with the inner circumference of the base plate portion 23 of the reinforcing ring 21, and a pair of rib portions 26, 26 that are connected to both sides of the solid plate portion 25 in the circumferential direction.

The rib portion 26 is provided discontinuously with the reinforcing ring 21, and is bent from the solid plate portion 25 to extend radially. The rib portion 26 faces the base portion 23 of the reinforcing ring 21 in the axial direction. When the reinforcing projection 22 is deformed radially outward by centrifugal force, the rib portion 26 butts against the base portion 23 in the axial direction. This butting makes it possible to resist the centrifugal force acting on the reinforcing projection 22. The butting portion between the rib portion 26 and the base portion 23 is formed on the outer diameter side of the base portion 23 to improve resistance.

The rib portion 26 is shaped so that it becomes shorter in the radial direction from the point where it butts against the base plate portion 23 toward one side in the axial direction.

The outer diameter of the reinforcing ring 21 is constant around the entire circumference. The outer diameter of the metal material 20 corresponds to the outer diameter of the reinforcing ring 21. The inner diameter of the reinforcing ring 21 corresponds to the diameter of an imaginary circle inscribed in the bent portion connected to the reinforcing protrusion 22.

The reinforcing protrusion 22 is formed to be thinner than the thickness of the base plate portion 23 of the reinforcing ring 21. This difference in thickness is satisfied between the reinforcing protrusion 22 and the base plate portion 23 as a whole. The base plate portion 23 is the main portion that exerts torsional rigidity, and since it does not affect the mass of the horn portion 8, it is preferable to make it thicker than the reinforcing protrusion 22. Since the reinforcing protrusion 22 affects the mass of the horn portion 8, it is preferable to make it as thin as possible. The thickness of the auxiliary flange portion 24 does not need to be as thick as the base plate portion 23, and is equal to or less than the thickness of the solid plate portion 25. Similarly, the auxiliary rib portion 26 does not need to be as thick as the base plate portion 23 or the solid plate portion 25, and is made thinner than the thickness of the solid plate portion 25.

The flange portion 24 has an exposed end portion 27 that is exposed from the synthetic resin 9 toward the other axial side. The exposed end portion 27 is made up of the tip surface of the flange portion 24 on the other axial side that is continuous around the entire circumference.

The total axial length of the reinforcing piece 22 is shorter than that of the first embodiment because the reinforcing effect is enhanced by the high rigidity of the pair of ribs 26, 26, thereby suppressing the centrifugal force acting on the reinforcing piece 22. The total axial length of the reinforcing piece 22 is more than 1/4 and less than half of the total axial length of the horn portion 8.

The entire reinforcing protrusion 22 is embedded in the synthetic resin 9. The entire remaining part of the reinforcing ring 21, except for the exposed end 27, is embedded in the synthetic resin 9. During insert molding, since almost the entire metal material 20 is embedded in the synthetic resin 9, it is possible to strongly integrate the metal material 20 and the synthetic resin 9 without bonding them with an adhesive. When inserting the metal material 20 into the mold, the exposed end of the metal material 20 that is continuous around the entire circumference is brought into contact with the mold at three or more locations that are evenly spaced in the circumferential direction, so that the central axis of the metal material 20 can be arranged to face the axial direction.

The manufacturing method for the reinforcing protrusions of the metal material 20 is shown generally in Figures 9(a) to 11(b).

9(a) and (b), the workpiece W is a flat blank plate punched out from a cold-rolled steel plate. The workpiece W is made up of an annular plate portion W1 as a reinforcing ring, and multiple bent pieces W2 that protrude from the inner diameter side plate edge of the annular plate portion W1 to the inner diameter side at equal intervals in the circumferential direction. The bent pieces W2 are made up of a rectangular plate portion W3 as a solid plate portion, and a pair of approximately triangular plate portions W4 as a pair of ribs. The approximately triangular plate portion W4 and the annular plate portion W1 are cut out when punched out from the cold-rolled steel plate, and a small clearance C is formed between the approximately triangular plate portion W4 and the annular plate portion W1. The bent pieces W2 are made thinner than the annular plate portion W1 by pressing when punching out from the cold-rolled steel plate, and the approximately triangular plate portion W4 in particular is made thinner.

Next, a pair of approximately triangular plate sections W4 are bent 90 degrees relative to the rectangular plate section W3 by metal pressing, so that they are erected in an axial and radial direction as shown in Figures 10(a) and 10(b).

Next, the rectangular plate portion W3 of the workpiece W is bent 90 degrees relative to the annular plate portion W1 by metal pressing, so that it extends in the axial direction as shown in Figures 11(a) and (b). This completes the reinforcing protrusion 22 consisting of a solid plate portion 25 and a pair of rib portions 26, 26, and the pair of rib portions 26, 26 are arranged so that they are in contact with or face each other in the axial direction with a small clearance on one side of the annular plate portion W1 on the axial direction, and butt against each other when deformed by centrifugal force.

Then, the flange portion 24 shown in Figures 7 and 8 is formed by metal pressing, bending the outer periphery of the annular plate portion W1 by 90 degrees, and the reinforcing ring 21 is completed. The flange portion 24 may also be formed when punching out the cold-rolled steel plate.

In the retainer according to the second embodiment, the reinforcing protrusions 22 are continuous with the inner circumference of the reinforcing ring 21, so that the reinforcing protrusions 22 are positioned further inward than in the first embodiment, thereby reducing the centrifugal force acting on the solid plate portion 25.

In addition, the retainer according to the second embodiment has a reinforcing protrusion 22 that is provided discontinuously with the reinforcing ring 21 and a rib portion 26 that is bent from the solid plate portion 25 so as to abut against a side surface on one axial side of the reinforcing ring 21 in the axial direction. This allows the rib portion 26 to abut against the side surface on one axial side of the reinforcing ring 21 to resist centrifugal force, thereby increasing the bending rigidity of the reinforcing protrusion 22 against centrifugal force. Also, the rib portion 26 can be bent to make it larger, thereby increasing the bending rigidity of the reinforcing protrusion 22 against centrifugal force.

In addition, in the cage according to the second embodiment, the rib portions 26 are formed on both circumferential sides of the reinforcing projection 22, and therefore the rib portions 26 butt against the reinforcing ring 21 on both circumferential sides of the reinforcing projection 22, further increasing the bending rigidity of the reinforcing projection 22 against centrifugal force. Note that the rib portions may be formed on only one of the circumferential sides of the reinforcing projection 22 (not shown), but forming the rib portions 26 on both circumferential sides of the reinforcing projection 22 as in the second embodiment results in superior bending rigidity of the reinforcing projection 22.

In addition, in the retainer according to the second embodiment, the reinforcing protrusions 22 are formed thinner than the thickness of the base portion 23 of the reinforcing ring 21, and the reinforcing protrusions 22 are made thinner with increased rigidity due to the formation of the rib portions 26, thereby reducing the mass of the reinforcing protrusions 22 and suppressing the centrifugal force acting on the reinforcing protrusions 22.

In addition, the retainer according to the second embodiment has a shape in which the rib portion 26 becomes shorter in the radial direction toward one side in the axial direction, so that the mass of the rib portion 26 can be reduced at the tip side of the reinforcing projection 22 without reducing the abutment portion between the rib portion 26 and the reinforcing ring 21, thereby further reducing the centrifugal force acting on the reinforcing projection 22.

In addition, in the cage according to the second embodiment, the reinforcing ring 21 has a flange portion 24 extending in the axial direction, which can further increase the rigidity of the reinforcing ring 21.

In addition, the retainer according to the second embodiment extends in the other axial direction so that the flange portion 24 has an exposed end portion 27 that is exposed from the synthetic resin 9 toward the other axial direction, and the entire remaining portion of the reinforcing ring 21, excluding the exposed end portion 27, is embedded in the synthetic resin 9. This allows insert molding to be performed in which the exposed end portion 27 of the flange portion 24 is utilized for positioning the metal material 20 in the mold, and most of the metal material 20 can be covered with the synthetic resin 9 to integrate the metal material 20 and the synthetic resin 9.

In the second embodiment, CAE analysis revealed that by changing the position of the reinforcing protrusion 22 to the inner diameter side as described above, thinning the reinforcing protrusion 22, adopting the rib portion 26, and adopting the flange portion 24, the rigidity of the retainer can be improved by nearly 170% compared to the first embodiment.

The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. Therefore, the scope of the present invention is indicated by the claims rather than the above description, and it is intended to include all modifications within the meaning and scope of the claims.

REFERENCE SIGNS LIST 1: cage 2: inner ring 3: outer ring 4: rolling element 7: annular portion 8: portion 9: synthetic resin 10, 20: metal material 11: pocket 12: solid base 13a, 13b: claws 14, 21: reinforcing ring 15, 22: reinforcing protrusion 16, 23: base plate portion 18, 27: exposed end portion 24: flange portion 25: solid plate portion 26: rib portion

Claims (13)

A cage comprising an annular portion and a plurality of horns protruding from the annular portion at equal intervals in the circumferential direction to one side in the axial direction, wherein spaces between adjacent horns in the circumferential direction form pockets for accommodating rolling elements, the annular portion and the plurality of horns being formed by insert molding that integrates a synthetic resin with a metal material, the metal material integrally having a reinforcing ring continuing around the entire circumference and a plurality of reinforcing projections protruding from the reinforcing ring to one side in the axial direction, the reinforcing ring being disposed on the annular portion, and the plurality of reinforcing projections being respectively disposed on the horns,
the reinforcing piece has a solid plate portion extending solidly from the reinforcing ring toward one side in the axial direction, the solid plate portion extending to one side and the other side in the circumferential direction of the horn,
The synthetic resin covers the solid plate portion from both radial and circumferential sides,
The reinforcing piece is continuous with the inner periphery of the reinforcing ring,
A retainer characterized in that the reinforcing projection is discontinuous with the reinforcing ring and has a rib portion bent from the solid plate portion so as to axially abut against a side surface on one axial side of the reinforcing ring . the reinforcing ring has a base plate portion which is continuous and solid around the entire circumference and extends in a radial direction, the base plate portion extending around the entire circumference to the inner diameter side and the outer diameter side of the annular portion,
2. The cage according to claim 1, wherein the base plate portion is entirely embedded in the synthetic resin. 3. The cage according to claim 1 , wherein the rib portion is formed on one or both sides in the circumferential direction of the reinforcing projection. 4. The cage according to claim 1 , wherein the reinforcing projection is formed to be thinner than a thickness of the base plate portion of the reinforcing ring. The cage according to claim 1 , wherein the rib portion is shaped so as to become shorter in the radial direction toward one axial side. The cage according to claim 1 , wherein the reinforcing ring has a flange portion extending in the axial direction. A cage comprising an annular portion and a plurality of horns protruding from the annular portion at equal intervals in the circumferential direction to one side in the axial direction, wherein spaces between adjacent horns in the circumferential direction form pockets for accommodating rolling elements, the annular portion and the plurality of horns being formed by insert molding that integrates a synthetic resin with a metal material, the metal material integrally having a reinforcing ring continuing around the entire circumference and a plurality of reinforcing projections protruding from the reinforcing ring to one side in the axial direction, the reinforcing ring being disposed on the annular portion, and the plurality of reinforcing projections being respectively disposed on the horns,
the reinforcing piece has a solid plate portion extending solidly from the reinforcing ring toward one side in the axial direction, the solid plate portion extending to one side and the other side in the circumferential direction of the horn,
The synthetic resin covers the solid plate portion from both radial and circumferential sides,
The retainer according to claim 1, wherein the reinforcing ring has a flange portion extending in the axial direction . A retainer as described in claim 6 or 7, wherein the flange portion extends to the other axial side so as to have an exposed end portion exposed from the synthetic resin toward the other axial side, and the entire remainder of the reinforcing ring excluding the exposed end portion is embedded in the synthetic resin. A retainer as described in any one of claims 1 to 8, wherein the reinforcing projection has an exposed end portion exposed from the synthetic resin toward one axial side, and the entire remainder of the reinforcing projection portion excluding the exposed end portion is embedded in the synthetic resin . The cage according to claim 1 , wherein the metal material is made of a cold-rolled steel plate. 11. The cage according to claim 10 , wherein the thickness of the metal material is 4% to 6% of the diameter of the rolling elements. 12. The cage according to claim 1 , wherein the synthetic resin is at least one of a thermosetting resin and a thermoplastic resin. A ball bearing comprising: the cage according to claim 1 ; an inner ring; an outer ring; and a plurality of the rolling elements disposed between the inner ring and the outer ring.

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