Bearing cage and manufacturing method therefor

Abstract

The resin injection gate is disposed at the pillar part. When the bearing cage is divided into first and second regions by an imaginary line connecting the resin injection gate and a weld to be formed at a position radially facing the resin injection gate, a resin reservoir that can store therein the melted resin is formed at the pillar part in only one of the regions. A circumferential distance between the resin reservoir and the weld is smaller than a circumferential distance between the resin reservoir and the resin injection gate. A cross-sectional area of a communicating part of the resin reservoir, which is configured to communicate with the pillar part, is equal to or less than a quarter of a cross-sectional area of the resin injection gate.

Claims

1. A manufacturing method of a bearing cage, the method comprising: forming the bearing cage by injecting melted resin from a resin injection gate, which is provided at a peripheral edge part of a substantially circular ring-shaped cavity formed in an injection mold, into the substantially circular ring-shaped cavity, wherein the bearing cage includes: a substantially circular ring-shaped base part, a plurality of pillar parts spaced with predetermined intervals in a circumferential direction and protruding axially from one axial end side surface of the base part, the plurality of pillar parts including at least a first pillar part and a second pillar part, and pockets whose number is equal to a number of the pillar parts formed by facing surfaces of a pair of the pillar parts adjacent to each other and one axial end side surface of the base part, wherein the resin injection gate is disposed at the first pillar part, wherein when the bearing cage is divided into first and second regions by an imaginary line connecting the resin injection gate and a weld line to be formed at a position radially facing the resin injection gate, a resin reservoir that can store therein the melted resin is formed at the second pillar part in only one of the regions, wherein a circumferential distance between the resin reservoir and the weld line is smaller than a circumferential distance between the resin reservoir and the resin injection gate, wherein a cross-sectional area of a communicating part of the resin reservoir, which is configured to communicate with the second pillar part, is equal to or less than a quarter of a cross-sectional area of the resin injection gate, wherein the resin reservoir is provided at the second pillar part where a thickness in a radial direction, of the second pillar part, is a largest thickness, in the radial direction, of the second pillar part, and wherein the radial direction is a direction from a radial center of the bearing cage to the second pillar part.

2. The manufacturing method of a bearing cage according to claim 1, wherein the plurality of pillar parts is odd in number, and wherein the second pillar part is adjacent, in the circumferential direction, the weld line.

3. The manufacturing method of a bearing cage according to claim 1, wherein the plurality of pillar parts is even in number, and wherein the resin injection gate is offset from a circumferentially central portion of the first pillar part.

4. The manufacturing method of a bearing cage according to claim 1, wherein the second pillar part, communicating with the resin reservoir, is provided adjacent to the weld line in the circumferential direction.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a plan view of a crown-shaped cage manufactured by a manufacturing method of a first embodiment.

(2) FIG. 2 is a plan view of a crown-shaped cage manufactured by a manufacturing method of a second embodiment.

(3) FIG. 3 is a plan view of a crown-shaped cage manufactured by a manufacturing method of a third embodiment.

(4) FIG. 4 is a plan view of a comb-shaped cage manufactured by a manufacturing method of a fourth embodiment.

(5) FIG. 5 is a plan view of a crown-shaped cage manufactured by a manufacturing method of a fifth embodiment.

(6) FIG. 6 is a plan view of a crown-shaped cage manufactured by a manufacturing method of a sixth embodiment.

(7) FIG. 7 is a plan view of a crown-shaped cage manufactured by a manufacturing method of a seventh embodiment.

(8) FIG. 8 is a plan view of a crown-shaped cage manufactured by a manufacturing method of an eighth embodiment.

(9) FIG. 9 is a plan view of a crown-shaped cage manufactured by a manufacturing method of a ninth embodiment.

(10) FIG. 10 is a plan view of a crown-shaped cage manufactured by a manufacturing method of a tenth embodiment.

(11) FIG. 11 is a plan view of a comb-shaped cage manufactured by a manufacturing method of an eleventh embodiment.

(12) FIG. 12 depicts a flowing aspect of melted resin in Embodiment 1.

(13) FIG. 13 depicts a flowing aspect of melted resin in Comparative Example 1.

(14) FIG. 14 depicts a flowing aspect of melted resin in Comparative Example 2.

(15) FIG. 15 depicts a flowing aspect of melted resin in Comparative Example 3.

(16) FIG. 16 is a sectional view of an injection mold that is to be used in a manufacturing method of a bearing cage of the related art.

DETAILED DESCRIPTION OF EMBODIMENTS

(17) Hereinafter, each embodiment of a bearing cage and a manufacturing method therefor of the present invention will be described in detail with reference to the drawings.

First Embodiment

(18) FIG. 1 depicts a bearing cage 1 (which will also be simply referred as ‘cage’, in the below) of a first embodiment. The cage 1 is a so-called crown-shaped cage, and includes a substantially circular ring-shaped base part 10, an odd number of pillar parts 20 (thirteen pillar parts, in the first embodiment) spaced with predetermined intervals in a circumferential direction and protruding axially from one axial end side surface 12 of the base part 10, and an odd number of pockets 30 (thirteen pockets, in the first embodiment), each of which is formed by facing surfaces 22, 22 of a pair of the pillar parts 20, 20 adjacent to each other and one axial end side surface 12 of the base part 10 and is configured to hold a rolling element (not shown) of a bearing. That is, the numbers of the pillar parts 20 and the pockets 30 are the same and are also odd, and the pillar parts 20 are provided at both circumferential sides of each of the pockets 30.

(19) As a manufacturing method of the cage 1, one point gate-type injection molding is adopted. Specifically, the cage 1 is formed by injecting melted resin having a reinforcing, fiber material added thereto from a resin injection gate (hereinafter, simply referred to as ‘gate’) 51, which is provided at a peripheral edge part of an inner periphery side of an annular cavity (not shown) formed in an injection mold, into the cavity and cooling and solidifying the melted resin. As the resin material, a resin composition in which a reinforcing fiber material (for example, glass fiber or carbon fiber) of 10 to 50 wt % is added to a polyamide-based resin such as 46 nylon and 66 nylon or a resin such as polybutylene terephthalate, polyphenylene sulfide (PPS), polyetheretherketone (PEEK), polyethernitrile (PEN) and the like is used. Meanwhile, in FIG. 1, although the cavity is not shown, an internal structure thereof is substantially the same as the structure of the cage 1.

(20) The gate 51 is supplied with the melted resin from a substantially cylindrical sprue 55 via a substantially cylindrical runner 53. The sprue 55 axially extends at a substantial center of the cage 1 (cavity), and is connected to the runner 53.

(21) The gate 51 is disposed at a position corresponding to the pillar part 20, i.e., a position at which it overlaps with the pillar part 20 in the circumferential direction. Therefore, the melted resin injected from the gate 51 into the cavity and flowing toward both circumferential sides is joined each other on a bottom of the pocket 30 radially facing the pillar part 20 at which the gate 51 is provided. In this case, a weld line W (which is shown with a broken line in FIG. 1) is formed on the bottom of the pocket 30.

(22) Here, the cage 1 (cavity) is bisected into first and second regions S1 and S2 by an imaginary line M connecting the gate 51 and the weld line W. At this time, a resin reservoir 40 that can store therein the melted resin is provided on an outer peripheral surface of the pillar part 20 in only one region (the first region S1, in the first embodiment) of the first and second regions S1 and S2. Therefore, when the resin reservoir 40 is provided at the pillar part 20 in the first region S1, like the first embodiment, the resin reservoir 40 is not provided in the second region S2. According to the resin reservoir 40 provided in this way, after the melted resin merges to form the weld line W, the melted resin is introduced into the resin reservoir 40. Therefore, a pressure gradient of the melted resin occurs between the weld line W and the resin reservoir 40 and a forcible resin flow is caused due to the pressure gradient, so that the reinforcing fiber material is suppressed from being oriented perpendicularly to the flow direction at the weld line W.

(23) A circumferential distance between the resin reservoir 40 and the weld line W is set shorter than a circumferential distance between the resin reservoir 40 and the gate 51. In the meantime, the circumferential distance between the resin reservoir 40 and the weld line W is preferably set to be extremely shorter. That is, like the first embodiment, the resin reservoir 40 is preferably provided at the first pillar part 20 (the pillar part 20 adjacent to the pocket 30 in which the weld line W is formed) in the circumferential direction from a position at which the weld line W is formed. Thereby, the forcible resin flow can be easily caused at the weld line W after the melted resin merges, so that the orientation of the reinforcing fiber material at the weld line W is suppressed and the strength of the weld line W is thus improved.

(24) A cross-sectional area of a communicating part 42 of the resin reservoir 40, which is configured to communicate with the pillar part 20, is set to be equal to or less than a quarter of a cross-sectional area of the gate 51. According to this configuration, after the melted resin merges to form the weld line W, the introduction of the melted resin into the resin reservoir 40 starts. Accordingly, it is possible to more securely realize the effect of suppressing the orientation of the reinforcing fiber material by the forcible resin flow at the weld line W.

Second Embodiment

(25) Subsequently, a manufacturing method of a bearing cage in accordance with a second embodiment of the present invention is described with reference to the drawing.

(26) As shown in FIG. 2, the second embodiment is different from the first embodiment, in that the resin reservoir 40 is provided on an inner peripheral surface of the pillar part 20. The other configurations are similar to the first embodiment, and the similar effects to the first embodiment can be accomplished.

Third Embodiment

(27) Subsequently, a manufacturing method of a bearing cage in accordance with a third embodiment of the present invention is described with reference to the drawing.

(28) As shown in FIG. 3, the third embodiment is different from the first and second embodiments, in that the resin reservoir 40 is provided on the outer peripheral surface of the second pillar part 20 in the circumferential direction from the position at which the weld line W is formed. Also in this configuration, since the circumferential distance between the resin reservoir 40 and the weld line W is set shorter than the circumferential distance between the resin reservoir 40 and the gate 51, the forcible resin flow can be easily caused at the weld line W after the melted resin merges, so that the orientation of the reinforcing fiber material at the weld line W is controlled and the strength of the weld line W is thus improved. The other configurations and effects are similar to the first and second embodiments.

Fourth Embodiment

(29) Subsequently, a manufacturing method of a bearing cage in accordance with a fourth embodiment of the present invention is described with reference to the drawing.

(30) FIG. 4 depicts a bearing cage 1A (which will also be simply referred to as ‘cage’, in the below) of the fourth embodiment. The cage 1A is a so-called comb-shaped cage, and includes a substantially circular ring-shaped base part 10A, an odd number of pillar parts 20A (thirteen pillar parts, in the fourth embodiment) spaced with predetermined intervals in a circumferential direction and protruding axially from one axial end side surface 12A of the base part 10A, and an odd number of pockets 30A (thirteen pockets, in the fourth embodiment), each of which is formed by facing surfaces 22A, 22A of a pair of the pillar parts 20A, 20A adjacent to each other and one axial end side surface 12A of the base part 10A and is configured to hold a rolling element (not shown) of a bearing. That is, the numbers of the pillar parts 20A and the pockets 30A are the same and are also odd, and the pillar parts 20A are provided at both circumferential sides of each of the pockets 30A.

(31) Also for the comb-shaped cage 1A, the similar manufacturing method to the embodiments can be applied.

(32) That is, the gate 51 is disposed at a position corresponding to the pillar part 20A, i.e., a position at which it overlaps with the pillar part 20A in the circumferential direction. Therefore, the melted resin injected from the gate 51 into the cavity and flowing toward both circumferential sides is joined each other on a bottom of the pocket 30A radially facing the pillar part 20A at which the gate 51 is provided. In this case, a weld line W (which is shown with a broken line in FIG. 4) is formed on the bottom of the pocket 30A.

(33) The resin reservoir 40 that can store therein the melted resin is provided on an inner peripheral surface of the pillar part 20A in only the first region S1 of the first and second regions S1 and S2 bisected by the imaginary line M. Also, the circumferential distance between the resin reservoir 40 and the weld line W is set shorter than the circumferential distance between the resin reservoir 40 and the gate 51. In the fourth embodiment, the resin reservoir 40 is provided at the first pillar part 20A (the pillar part 20A adjacent to the pocket 30A in which the weld line W is formed) in the circumferential direction from the position at which the weld line W is formed. Also, the cross-sectional area of the communicating part 42 of the resin reservoir 40, which is configured to communicate with the pillar part 20A, is set to be equal to or less than a quarter of the cross-sectional area of the gate 51.

(34) As described above, also in the manufacturing method of the comb-shaped cage 1A, the similar effects to the embodiments can be accomplished.

Fifth Embodiment

(35) FIG. 5 depicts a bearing cage 1 (which will also be simply referred as ‘cage’, in the below) of a fifth embodiment. The cage 1 is a so-called crown-shaped cage, and includes a substantially circular ring-shaped base part 10, an even number of pillar parts 20 (fourteen pillar parts, in the fifth embodiment) spaced with predetermined intervals in a circumferential direction and protruding axially from one axial end side surface 12 of the base part 10, and an even number of pockets 30 (fourteen pockets, in the fifth embodiment), each of which is formed by facing surfaces 22, 22 of a pair of the pillar parts 20, 20 adjacent to each other and one axial end side surface 12 of the base part 10 and is configured to hold a rolling element (not shown) of a bearing. That is, the numbers of the pillar parts 20 and the pockets 30 are the same and are also even, and the pillar parts 20 are provided at both circumferential sides of each of the pockets 30.

(36) As a manufacturing method of the cage 1, one point gate-type injection molding is adopted. Specifically, the cage 1 is formed by injecting melted resin having a reinforcing fiber material added thereto from a resin injection gate (hereinafter, simply referred to as ‘gate’) 51, which is provided at a peripheral edge part of an inner periphery side of an annular cavity (not shown) formed in an injection mold, into the cavity and cooling and solidifying the melted resin. As the resin material, a resin composition in which a reinforcing fiber material (for example, glass fiber or carbon fiber) of 10 to 50 wt % is added to a polyamide-based resin such as 46 nylon and 66 nylon or a resin such as polybutylene terephthalate, polyphenylene sulfide (PPS), polyetheretherketone (PEEK), polyethernitrile (PEN) and the like is used. Meanwhile, in FIG. 5, although the cavity is not shown, an internal structure thereof is substantially the same as the structure of the cage 1.

(37) The gate 51 is supplied with the melted resin from a substantially cylindrical sprue 55 via a substantially cylindrical runner 53. The sprue 55 axially extends at a substantial center of the cage 1 (cavity), and is connected to the runner 53.

(38) The gate 51 is disposed at a position corresponding to the pillar part 20, i.e., a position at which it overlaps with the pillar part 20 in the circumferential direction. Particularly, in the fifth embodiment, the gate 51 is disposed at a circumferentially central portion of the pillar part 20. Therefore, the melted resin injected from the gate 51 into the cavity and flowing toward both circumferential sides is joined each other at a circumferentially central portion of the pillar part 20 radially facing the pillar part 20 at which the gate 51 is provided. In this case, a weld line W (which is shown with a broken line in FIG. 5) is formed at the circumferentially central portion of the pillar part 20.

(39) Here, the cage 1 (cavity) is bisected into first and second regions S1 and S2 by an imaginary line M connecting the gate 51 and the weld line W. At this time, a resin reservoir 40 that can store therein the melted resin is provided on an outer peripheral surface of the pillar part 20 in only one region (the first region S1, in the fifth embodiment) of the first and second regions S1 and S2. Therefore, when the resin reservoir 40 is provided at the pillar part 20 in the first region S like the fifth embodiment, the resin reservoir 40 is not provided in the second region S2. According to the resin reservoir 40 provided in this way, after the melted resin merges to form the weld line W, the melted resin is introduced into the resin reservoir 40. Therefore, a pressure gradient of the melted resin occurs between the weld line W and the resin reservoir 40 and a forcible resin flow is caused due to the pressure gradient, so that the reinforcing fiber material is suppressed from being oriented perpendicularly to the flow direction at the weld line W.

(40) Also, the strength is a little decreased in the vicinity of a part at which the resin injection gate 51 or the resin reservoir 40 is provided, although the decrease in the strength is less than at the part at which the weld line W is formed. However, since the resin injection gate 51 or the resin reservoir 40 is provided at the pillar part 20 having an axial thickness larger than the pocket 30, it is possible to suppress the decrease in the strength of the bearing cage 1.

(41) A circumferential distance between the resin reservoir 40 and the weld line W is set shorter than a circumferential distance between the resin reservoir 40 and the gate 51. In the meantime, the circumferential distance between the resin reservoir 40 and the weld line W is preferably set to be extremely shorter. That is, like the fifth embodiment, the resin reservoir 40 is preferably provided at the first pillar part 20 (the pillar part 20 adjacent to the pillar part 20 at which the weld line W is formed) in the circumferential direction from a position at which the weld line W is formed. Thereby, the forcible resin flow can be easily caused at the weld line W after the melted resin merges, so that the orientation of the reinforcing fiber material at the weld line W is suppressed and the strength of the weld line W is thus improved.

(42) A cross-sectional area of a communicating part 42 of the resin reservoir 40, which is configured to communicate with the pillar part 20, is set to be equal to or less than a quarter of a cross-sectional area of the gate 51. According to this configuration, after the melted resin merges to form the weld line W, the introduction of the melted resin into the resin reservoir 40 starts. Accordingly, it is possible to more securely realize the effect of suppressing the orientation of the reinforcing fiber material by the forcible resin flow at the weld line W.

(43) In the meantime, the resin reservoir 40 is not limited to the configuration where it is provided on the outer peripheral surface of the pillar part 20. That is, even when the resin reservoir 40 is provided on an inner peripheral surface of the pillar part 20, the similar effects can be accomplished.

(44) Also, the pillar part 20 at which the resin reservoir 40 is provided is not particularly limited inasmuch as the circumferential distance between the resin reservoir 40 and the weld line W is set smaller than the circumferential distance between the resin reservoir 40 and the gate 51. That is, the resin reservoir 40 may be provided at the second or third pillar part 20 in the circumferential direction from the pillar part 20 at which the weld line W is formed. Also in this case, since the circumferential distance between the resin reservoir 40 and the weld line W is set smaller than the circumferential distance between the resin reservoir 40 and the gate 51, the forcible resin flow can be easily caused at the weld line W after the melted resin merges, so that the orientation of the reinforcing fiber material at the weld line W is controlled and the strength of the weld line W is thus improved.

Sixth Embodiment

(45) Subsequently, a manufacturing method of a bearing cage in accordance with a sixth embodiment of the present invention is described with reference to the drawing.

(46) As shown in FIG. 6, the sixth embodiment is different from the fifth embodiment, in that the gate 51 is disposed at a position deviating in one circumferential direction (a counterclockwise direction, in FIG. 6) from the circumferentially central portion of the pillar part 20. In this case, the melted resin injected from the gate 51 into the cavity and flowing toward both circumferential sides is joined each other at a position radially facing the pillar part 20 at which the gate 51 is provided, and the joined part becomes the weld line W. That is, the weld line W is formed between the circumferentially central portion of the pillar part 20 and the bottom of the pocket 30 in the circumferential direction. In the meantime, the bottom of the pocket 30 is a part, which is positioned at a circumferentially central portion of the pocket 30 and at which the axial thickness of the pocket 30 is smallest.

(47) Here, regarding the first and second regions S1 and S2, a region including the pillar part 20L, in which the bottom of the pocket 30 does not exist between the pillar part 20L, and the weld line W, of the pair of pillar parts 20L, 20R adjacent to the weld line W in the circumferential direction is set as the first region S1. At this time, the resin reservoir 40 is provided on the outer peripheral surface of the pillar part 20 in only the first region S1. On the other hand, the resin reservoir 40 is not provided at the pillar part 20 in the second region S2.

(48) The resin reservoir 40 is disposed in this way, so that after the melted resin merges to form the weld line W, the forcible flow of the melted resin is caused at the weld line W in a direction in which a cross-sectional area of a flow path increases (a direction facing toward the first region S1). Accordingly, the orientation of the reinforcing fiber material at the weld line W is suppressed and a region in which the fiber orientation is disturbed is moved to a part of which the cross-sectional area is larger, so that it is possible to further improve the strength of the weld line W.

(49) Particularly, in the sixth embodiment, since the resin reservoir 40 is provided at the pillar part 20L (the first pillar part 20L in the circumferential direction from the position at which the weld line W is formed), which is adjacent to the weld line W in the circumferential direction, of the pillar parts 20 in the first region S1, the forcible resin flow can be easily caused at the weld line W after the melted resin merges, so that the orientation of the reinforcing fiber material of the weld line W is controlled and the strength of the weld line W is thus improved.

Seventh Embodiment

(50) Subsequently, a manufacturing method of a bearing cage in accordance with a seventh embodiment of the present invention is described with reference to the drawing.

(51) As shown in FIG. 7, the seventh embodiment is different from the sixth embodiment, in that the resin reservoir 40 is provided on the inner peripheral surface of the pillar part 20. The other configurations are similar to the sixth embodiment, and the similar effects to the sixth embodiment can be accomplished.

Eighth Embodiment

(52) Subsequently, a manufacturing method of a bearing cage in accordance with an eighth embodiment of the present invention is described with reference to the drawing.

(53) As shown in FIG. 8, the eighth embodiment is different from the fifth to seventh embodiments, in that the resin reservoir 40 is provided on the outer peripheral surface of the second pillar part 20 in the circumferential direction from the position at which the weld line W is formed.

(54) Also in this configuration, since the resin reservoir 40 is provided in the first region S1, the orientation of the reinforcing fiber material at the weld line W is controlled and a region in which the fiber orientation is disturbed is moved to a part of which the cross-sectional area is larger, so that it is possible to further improve the strength of the weld line W. Also, since the circumferential distance between the resin reservoir 40 and the weld line W is set smaller than the circumferential distance between the resin reservoir 40 and the gate 51, the forcible resin flow can be easily caused at the weld line W after the melted resin merges, so that the orientation of the reinforcing fiber material at the weld line W is controlled and the strength of the weld line W is thus improved. The other configurations and effects are similar to the above embodiments.

Ninth Embodiment

(55) Subsequently, a manufacturing method of a bearing cage in accordance with a ninth embodiment of the present invention is described with reference to the drawing.

(56) As shown in FIG. 9, the ninth embodiment is different from the eighth embodiment, in that the resin reservoir 40 is provided on the inner peripheral surface of the pillar part 20. The other configurations are similar to the eighth embodiment, and the similar effects to the eighth embodiment can be accomplished.

Tenth Embodiment

(57) Subsequently, a manufacturing method of a bearing cage in accordance with a tenth embodiment of the present invention is described with reference to the drawing.

(58) As shown in FIG. 10, the tenth embodiment is different from the fifth to ninth embodiments, in that the resin reservoir 40 is provided on the outer peripheral surface of the third pillar part 20 in the circumferential direction from the position at which the weld line W is formed. The other configurations are similar to the fifth to ninth embodiments, and the similar effects to the fifth to ninth embodiments can be accomplished.

(59) In the meantime, the resin reservoir 40 is not limited to the configuration where it is provided on the outer peripheral surface of the pillar part 20. That is, even when the resin reservoir 40 is provided on the inner peripheral surface of the pillar part 20, the similar effects can be accomplished.

(60) Also, the pillar part 20 at which the resin reservoir 40 is provided is not particularly limited inasmuch as the resin reservoir is provided at the pillar part 20 in only the first region S1 and the circumferential distance between the resin reservoir 40 and the weld line W is set smaller than the circumferential distance between the resin reservoir 40 and the gate 51.

Eleventh Embodiment

(61) Subsequently, a manufacturing method of a bearing cage in accordance with an eleventh embodiment of the present invention is described with reference to the drawing.

(62) FIG. 11 depicts a bearing cage 1A (which will also be simply referred to as ‘cage’, in the below) of the eleventh embodiment. The cage 1A is a so-called comb-shaped cage, and includes a substantially circular ring-shaped base part 10A, an even number of pillar parts 20A (fourteen pillar parts, in the eleventh embodiment) spaced with predetermined intervals in a circumferential direction and protruding axially from one axial end side surface 12A of the base part 10A, and an even number of pockets 30A (fourteen pockets, in the eleventh embodiment), each of which is formed by facing surfaces 22A, 22A of a pair of the pillar parts 20A, 20A adjacent to each other and one axial end side surface 12A of the base part 10A, and is configured to hold a rolling element (not shown) of a bearing. That is, the numbers of the pillar parts 20A and the pockets 30A are the same and are also even, and the pillar parts 20A are provided at both circumferential sides of each of the pockets 30A.

(63) Also for the comb-shaped cage 1A, the similar manufacturing method to the fifth to tenth embodiments can be applied.

(64) That is, the gate 51 is disposed at a position corresponding to the pillar part 20A, i.e., a position at which it overlaps with the pillar part 20A in the circumferential direction. Therefore, the melted resin injected from the gate 51 into the cavity and flowing toward both circumferential sides is joined each other at a circumferentially central portion of the pillar part 20A radially facing the pillar part 20A at which the gate 51 is provided. In this case, a weld line W (which is shown with a broken line in FIG. 11) is formed at the circumferentially central portion of the pillar part 20A.

(65) The resin reservoir 40 that can store therein the melted resin is provided on an inner peripheral surface of the pillar part 20A in only the first region S1 of the first and second regions S1 and S2 bisected by the imaginary line M. Also, the circumferential distance between the resin reservoir 40 and the weld line W is set shorter than the circumferential distance between the resin reservoir 40 and the gate 51. In the eleventh embodiment, the resin reservoir 40 is provided at the first pillar part 20A (the pillar part 20A adjacent to the pillar part 20A, at which the weld line W is formed, in the circumferential direction) in the circumferential direction from the pillar part 20A at which the weld line W is formed. Also, the cross-sectional area of the communicating part 42 of the resin reservoir 40, which is configured to communicate with the pillar part 20A, is set to be equal to or less than ¼ of the cross-sectional area of the gate 51.

(66) As described above, also in the manufacturing method of the comb-shaped cage 1A, the similar effects to the fifth to tenth embodiments can be accomplished.

(67) In the meantime, the resin reservoir 40 is not limited to the configuration where it is provided on the inner peripheral surface of the pillar part 20A. That is, even when the resin reservoir 40 is provided on the outer peripheral surface of the pillar part 20A, the similar effects can be accomplished.

(68) Also, the pillar part 20A at which the resin reservoir 40 is provided is not particularly limited inasmuch as the circumferential distance between the resin reservoir 40 and the weld line W is set smaller than the circumferential distance between the resin reservoir 40 and the gate 51. That is, the resin reservoir 40 may be provided at the second or third pillar part 20A in the circumferential direction from the pillar part 20A at which the weld line W is formed. Also in this case, since the circumferential distance between the resin reservoir 40 and the weld line W is set smaller than the circumferential distance between the resin reservoir 40 and the gate 51, the forcible resin flow can be easily caused at the weld line W after the melted resin merges, so that the orientation of the reinforcing fiber material at the weld line W is controlled and the strength of the weld line W is thus improved.

(69) Also, the manufacturing methods of the crown-shaped cage 1 in accordance with the fifth to tenth embodiments can be applied to the manufacturing method of the comb-shaped cage 1A.

(70) Like this, the manufacturing method of the bearing cage of the present invention is not limited to the crown-shaped cage 1 and the comb-shaped cage 1A, and can be applied to a variety of cages.

Embodiment 1

(71) Subsequently, an analysis result of a relation between the cross-sectional area of the communicating part 42 of the resin reservoir 40 and the cross-sectional area of the resin injection gate 51 is described.

(72) As shown in FIGS. 12 to 15 and Table 1, in Embodiment 1 and Comparative Examples 1 to 3, a cavity 60 is configured as a simple circular ring model, a diameter (the cross-sectional area) of the resin injection gate 51 is made constant, a diameter (the cross-sectional area) of the communicating part 42 of the resin reservoir 40 is changed, and a flowing state of the melted resin G is analyzed by resin flow analysis software “3D TIMON” available from Toray Engineering Co., Ltd

(73) TABLE-US-00001 TABLE 1 Comparative Comparative Comparative Embodiment 1 Example 1 Example 2 Example 3 (FIG. 12) (FIG. 13) (FIG. 14) (FIG. 15) diameter of gate (mm) 1.2 cross-sectional area of gate (mm) 1.13 diameter of communicating part 0.6 0.8 1 1.2 of resin reservoir (mm) cross-sectional area of 0.28 0.50 0.79 1.13 communicating part of resin reservoir (mm) ratio of cross-sectional area 0.25 0.44 0.69 1.00 of communicating part of resin reservoir to cross-sectional area of gate filling pattern The melted resin The melted resin is introduced into is not introduced the resin reservoir before merger. into the resin reservoir before merger.

(74) As shown in Comparative Examples 1 to 3 of FIGS. 13 to 15, when the ratio of the cross-sectional area of the communicating part 42 to the cross-sectional area of the resin injection gate 51 is 0.44 to 1.00, the introduction of the melted resin G into the resin reservoir 40 starts before the melted resin G merges each other. In this case, the effect of causing the forcible resin flow at the weld line W after the melted resin G merges is reduced, so that it is difficult to realize the effect of controlling the orientation of the reinforcing fiber material at the weld line W.

(75) On the other hand, as shown in Embodiment of FIG. 12, when the ratio of the cross-sectional area of the communicating part 42 to the cross-sectional area of the resin injection gate 51 is 0.25, the melted resin G is not introduced into the resin reservoir 40 until the melted resin G merges. For this reason, after the melted resin G merges to form the weld line W, the effect of causing the forcible resin flow at the weld line W is large, so that the effect of controlling the orientation of the reinforcing fiber material at the weld line W is realized.

(76) Like this, it is clear that when the cross-sectional area of the communicating part 42 of the resin reservoir 40 is equal to or less than a quarter of the cross-sectional area of the resin injection gate 51, the melted resin G is not introduced into the resin reservoir 40 until the melted resin G merges, so that the effect of controlling the orientation of the reinforcing fiber material at the weld line W is realized.

(77) In the meantime, the present invention is not limited to the respective embodiments, and can be appropriately modified and improved.

(78) Also, the bearing cage of the present invention can be applied to a rolling bearing because the decrease in the strength is small and the durability is excellent. That is, since the rolling bearing includes an inner ring, an outer ring, a plurality of rolling elements provided between the inner ring and the outer ring, and a bearing cage configured to rollably keep the rolling elements in pockets and having the excellent durability, it is possible to meet requirements such as high-speed rotation, high load and the like.

DESCRIPTION OF REFERENCE NUMERALS

(79) 1, 1A: bearing cage 10, 10A: base part 12, 12A: one axial end side surface 20, 20A, 20L, 20R: pillar part 22, 22A: surface 30, 30A: pocket 40: resin reservoir 42: communicating part 51: resin injection gate 53: runner 55: sprue 60: the cavity G: melted resin M: imaginary line S1: first region S2: second region W: weld line