JP6413728B2 - Manufacturing method of bearing cage - Google Patents

Description

  The present invention relates to a method for manufacturing a bearing cage.

  Generally, the bearing cage is manufactured by injection molding. Specifically, as shown in FIG. 7, an annular cavity 140 corresponding to a bearing cage that is a molded body is formed in a molding die, and a resin injection gate 150 provided at the peripheral portion of the cavity 140 is used. It is manufactured by injecting a dissolved resin material (thermoplastic resin) and solidifying by cooling.

  The molten resin injected into the cavity 140 flows into the cavity 140 as two flows on both sides in the circumferential direction, and merges again at a position opposite to the resin injection gate 150 in the radial direction and joined to each other. , A weld 100W is formed. Generally, since the resin cage for bearings thus molded by injection is only one in which the molten resin is fused and integrated, uniform mixing of the molten resin does not occur, and the strength decreases in the weld 100W. Is well known.

  Further, when a reinforcing fiber material such as glass fiber, carbon fiber, or metal fiber is added as a reinforcing material to the molten resin, the reinforcing fiber material is oriented perpendicular to the flowing direction of the molten resin in the weld 100W. Does not develop. Furthermore, in portions other than the weld 100W, the reinforcing fiber material is oriented in parallel with the flow direction of the dissolved resin, so that the strength difference between the portion and the weld becomes large.

  Thus, the resin cage for bearings manufactured by injection molding often breaks from weak welds. In particular, when the weld is formed at a portion where stress is most easily concentrated (for example, at the pocket bottom where the wall thickness is the thinnest in the pocket, or at the corner R portion where the annular portion and the column portion intersect), the portion. Damage tends to occur, and the durability of the cage is impaired. Therefore, conventionally, the following countermeasures have been taken.

  In the method for manufacturing a synthetic resin cage of Patent Document 1, gates are provided at a plurality of locations in the circumferential direction of the cavity of the molding die. Further, among the plurality of regions between the gates, the circumferential distance of some regions is set to be longer than the circumferential distance of other regions, and the injection resin material merging point in the region having a long circumferential distance Only the resin reservoir is provided. Thus, the injected injected resin material is caused to flow from the cavity into the resin reservoir to prevent the weld strength from being lowered.

  In the resin cage of Patent Document 2, the total number of pocket portions is an odd number, and the number of pocket portions arranged between the gates is the most even. The hot water pool is positioned at one of the pillar portions formed at both ends of the pocket portion located at the center in the circumferential direction between the gates where the pocket portion is an odd number. Thereby, the weld formed in the region between the gates where the pocket portion is odd is formed at a position deviated in the circumferential direction from the bottom portion of the pocket portion, thereby improving the rigidity of the cage.

Japanese Patent No. 3666536 JP 2008-095770 A

  However, in the manufacturing method described in Patent Document 1, a resin reservoir is provided at a joint location of the injected resin material, that is, a position that coincides with the weld formation position. Therefore, there is a problem that the reinforcing fiber material is easily oriented perpendicular to the flow direction of the resin material in the vicinity of the communication portion (opening) of the resin reservoir communicating with the cavity, and the weld reinforcement effect cannot be sufficiently obtained.

  In the resin cage described in Patent Document 2, in the region between the gates where there is no hot water pool and the pocket portion is an even number, a weld is formed in which the molten resin is simply welded and integrated with the pillar portion. Therefore, the weld strength may be insufficient depending on the use conditions.

  This invention is made | formed in view of the subject mentioned above, The objective is to provide the manufacturing method of the cage for bearings which can suppress a strength fall.

The above object of the present invention can be achieved by the following constitution.
(1) Manufacture of a bearing cage molded by injecting a molten resin into the cavity from three resin injection gates provided at the peripheral edge of a substantially annular cavity formed in the molding die. A method,
The bearing cage is
A substantially annular base;
An even number of 3 column portions protruding in the axial direction at a predetermined interval in the circumferential direction from the axial one end side surface of the base portion;
The same number of pockets as the pillars formed by the mutually opposing surfaces of a pair of adjacent pillars and the axial one end side surface of the base;
Have
When the regions between the resin injection gates adjacent to each other are first to third regions,
The three resin injection gates are respectively provided at positions shifted from the circumferential center of the column portion to the circumferential one side so that the number of the pockets in the first to third regions is equal to each other.
At the center in the circumferential direction of the column portion furthest away from both ends of the first to third regions, a resin reservoir capable of storing the dissolved resin is provided, respectively.
The bearing cage manufacturing method according to claim 1, wherein a cross-sectional area of the communication portion of the resin reservoir communicating with the column portion is ¼ or less of a cross-sectional area of the resin injection gate.

According to the manufacturing method of the bearing cage of the present invention, the three resin injection gates are respectively provided with columns so that the number of columns is set to an even number and the number of pockets in the first to third regions is equal to each other. The resin pool is provided at a position shifted from the circumferential center of the portion to one side in the circumferential direction, and in the circumferential center of the column portion furthest away from both ends of the first to third regions. It is done.
Therefore, the melted resin supplied from each resin injection gate is displaced in the vicinity of the column part farthest from both ends of the first to third regions, more specifically, from the circumferential center of the column part to one side in the circumferential direction. The welds are formed at the different positions, and a weld is formed. Here, since the resin reservoir is provided at the center in the circumferential direction of the column portion, the weld formation position and the resin reservoir arrangement position are shifted in the circumferential direction, and a pressure gradient of the dissolved resin is easily generated between the weld and the resin reservoir. Become. Therefore, the forced resin flow caused by the pressure gradient can prevent the reinforcing fiber material from being oriented perpendicular to the flow direction of the dissolved resin in the weld.
In particular, as described above, the weld is formed at a position shifted from the circumferential center of the column part to one side in the circumferential direction, and the resin reservoir is disposed at the circumferential center of the column part. The forced flow of the dissolved resin occurs in the direction in which the cross-sectional area of the flow path increases. Therefore, since the region in which the fiber orientation is disturbed in the weld moves to a portion having a large cross-sectional area, the weld strength is further improved.
Further, since the cross-sectional area of the communication portion of the resin reservoir is ¼ or less of the cross-sectional area of the resin injection gate, the inflow of the molten resin into the resin reservoir starts after the molten resin merges, and the forced in the weld The effect of controlling the orientation of the reinforcing fiber material by the flow of the resin can be expressed more reliably.

It is a top view of the crown-shaped cage manufactured by the manufacturing method concerning a 1st embodiment. It is a top view of the crown-shaped cage manufactured by the manufacturing method concerning a 2nd embodiment. In Example 1, it is a figure which shows a mode that melt | dissolution resin flows. In comparative example 1, it is a figure showing signs that melted resin flows. In Comparative example 2, it is a figure which shows a mode that melt | dissolution resin flows. In comparative example 3, it is a figure showing signs that dissolution resin flows. It is sectional drawing of the shaping die used for the manufacturing method of the conventional bearing retainer.

  Hereinafter, each embodiment of the manufacturing method of the bearing retainer concerning the present invention is described in detail based on a drawing.

(First embodiment)
FIG. 1 shows a bearing cage 1 of the present embodiment (hereinafter, simply referred to as a cage). The cage 1 is a so-called crown-shaped cage, and has a substantially annular base portion 10 and a plurality of even-numbered multiples of 3 and 3 protruding in the axial direction at a predetermined interval in the circumferential direction from the axial end surface 12 of the base portion 10 ( 12 in the present embodiment), and a pair of adjacent pillars 20, 20, which are opposed to each other, 22 and 22, and one axial side surface 12 of the base 10, and is a rolling element (non-rotating member) of the bearing. And a plurality of even-numbered multiples 3 (12 in the present embodiment) of pockets 30. That is, the number of the column parts 20 and the pockets 30 is the same, and both are formed by an even multiple of 3. The column parts 20 are provided on both sides in the circumferential direction of the respective pockets 30.

  In such a manufacturing method of the cage 1, a three-point gate type injection molding is adopted. Specifically, the cage 1 includes three resin injection gates (hereinafter simply referred to as gates) 51 provided on the outer peripheral side peripheral portion of an annular cavity (not shown) formed in the molding die. The molten resin to which the reinforcing fiber material is added is injected into the cavity and molded by cooling and solidifying. Examples of resin materials include polyamide resins such as 46 nylon and 66 nylon, resins such as polybutylene terephthalate, polyphenylene sulfide (PPS), polyether ether ketone (PEEK), and polyether nitrile (PEN). % Of a reinforcing fiber material (for example, glass fiber or carbon fiber) is used. In FIG. 1, the cavity is not shown, but its internal structure is substantially the same as the structure of the cage 1.

  Dissolved resin is supplied to each gate 51 from a substantially cylindrical sprue 55 via a substantially cylindrical runner 53 extending in the radial direction. The sprue 55 extends in the axial direction at the approximate center of the cage 1 (cavity) and is connected to the runner 53. Therefore, the molten resin supplied from the sprue 55 reaches each gate 51 via each runner 53 and flows into the cavity from each gate 51 simultaneously.

  Assuming that the region between the adjacent gates 51 is the first to third regions S1 to S3, the three gates 51 are arranged so that the number of pockets 30 in the first to third regions S1 to S3 is equal to each other. The In the present embodiment, the number of pockets 30 in each of the first to third regions S1 to S3 is four. The three gates 51 are provided at positions shifted from the center in the circumferential direction of the column part 20 to one side in the circumferential direction (counterclockwise in the figure).

  A column 20 that is farthest from both ends (positions where the gate 51 is provided) of the first to third regions S1 to S3 is provided with a resin reservoir 40 capable of storing a dissolved resin. The resin reservoir 40 communicates with the outer peripheral surface at the center in the circumferential direction of the column part 20.

  In such a configuration, the vicinity of the column portion 20 farthest from both ends of the first to third regions S1 to S3 between the adjacent gates 51 that are injected from the gate 51 into the cavity, more specifically, the column portion. The weld W is formed at a position shifted from the circumferential center of 20 toward one side in the circumferential direction. Here, since the resin reservoir 40 is provided at the center in the circumferential direction of the column portion 20, the weld W forming position and the resin reservoir 40 disposition position are shifted in the circumferential direction, and the molten resin is interposed between the weld W and the resin reservoir 40. The pressure gradient is likely to occur. Therefore, the forced flow of the resin due to the pressure gradient can prevent the reinforcing fiber material from being oriented perpendicular to the flow direction of the dissolved resin in the weld W. In particular, as described above, the weld W is formed at a position shifted from the circumferential center of the column portion 20 to one side in the circumferential direction, and the resin reservoir 40 is disposed at the circumferential center of the column portion 20. The forced flow of the dissolved resin occurs in the direction in which the cross-sectional area of the flow path increases from W toward the resin reservoir 40. Therefore, since the region in which the fiber orientation is disturbed in the weld W moves to a portion having a large cross-sectional area, it has an effect of further improving the weld W strength. As described above, the orientation of the reinforcing fiber material of the weld W is controlled, the weld W strength is improved, and consequently the strength reduction of the cage 1 can be suppressed.

  Here, the cross-sectional area of the communication portion 42 of the resin reservoir 40 that communicates with the column portion 20 and is an opening to the cavity is set to ¼ or less of the cross-sectional area of the gate 51. According to this, since the melted resin merges and the weld W is formed after the weld W is formed, the orientation of the reinforcing fiber material is controlled by the forced resin flow in the weld W. An effect can be expressed more reliably.

(Second Embodiment)
Next, the manufacturing method of the bearing retainer according to the second embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 2, the present embodiment is different from the above-described embodiment in that a resin reservoir 40 is provided on the inner peripheral surface of the column portion 20. Other configurations are the same as those in the above embodiment, and the same effects as those in the above embodiment can be obtained.

(Example)
Next, the analysis result about the relationship between the cross-sectional area of the communication part 42 of the resin reservoir 40 and the cross-sectional area of the resin injection gate 51 will be described.

  As shown in FIGS. 3 to 6 and Table 1, in Example 1 and Comparative Examples 1 to 3, the cavity 60 is a simple simple ring model, the diameter (cross-sectional area) of the resin injection gate 51 is constant, and the resin reservoir 40 The state in which the dissolved resin G flows when the diameter (cross-sectional area) of the communication portion 42 of the resin was changed was analyzed by a resin flow analysis software “3D TIMON” manufactured by Toray Engineering Co., Ltd.

  As shown in Comparative Examples 1 to 3 in FIGS. 4 to 6, when the ratio of the cross-sectional area of the communication portion 42 to the cross-sectional area of the resin injection gate 51 is 0.44 to 1.00, the dissolved resins G merge. Before, the inflow of the dissolved resin G into the resin reservoir 40 starts. In these cases, the effect of forcibly causing the resin to flow in the weld W after the molten resin G merges is small, and the effect of controlling the orientation of the reinforcing fiber material in the weld W is difficult to be exhibited.

  On the other hand, when the ratio of the cross-sectional area of the communication portion 42 to the cross-sectional area of the resin injection gate 51 is 0.25, as shown in the first embodiment of FIG. The dissolved resin G does not flow into. For this reason, after melt | dissolution resin G merges and the weld W is formed, the effect which raise | generates forced resin flow to the weld W is large, and the effect which controls the orientation of the reinforcing fiber material in the weld W is expressed.

  Thus, when the cross-sectional area of the communication portion 42 of the resin reservoir 40 is ¼ or less of the cross-sectional area of the resin injection gate 51, the molten resin G flows into the resin reservoir 40 before the molten resin G merges. It became clear that the effect which controls the orientation of the reinforcing fiber material in the weld W was expressed.

  In addition, this invention is not limited to each embodiment mentioned above, A deformation | transformation, improvement, etc. are possible suitably.

  Thus, the manufacturing method of the bearing cage of the present invention is not limited to the above-described crown-shaped cage 1 and can be applied to various types of cages such as a comb-shaped cage.

  In addition, the bearing cage of the present invention is suitable for rolling bearings because it is less durable and excellent in durability. That is, such a rolling bearing has an inner ring, an outer ring, a plurality of rolling elements provided between the inner ring and the outer ring, and the rolling element is held in a pocket so that the rolling element can roll freely, and has excellent durability. Can satisfy the requirements such as high-speed rotation and high load.

DESCRIPTION OF SYMBOLS 1 Bearing cage 10 Base 12 One axial side surface 20 Column 22 Opposite surface 30 Pocket 40 Resin reservoir 42 Communication part 51 Resin injection gate 53 Runner 55 Sprue 60 Cavity G Dissolved resin S1-S3 Area W Weld

Claims (1)

A method of manufacturing a bearing retainer that is molded by injecting a molten resin into the cavity from three resin injection gates provided at the peripheral edge of a substantially annular cavity formed in a molding die. And
The bearing cage is
A substantially annular base;
An even number of 3 column portions protruding in the axial direction at a predetermined interval in the circumferential direction from the axial one end side surface of the base portion;
The same number of pockets as the pillars formed by the mutually opposing surfaces of a pair of adjacent pillars and the axial one end side surface of the base;
Have
When the regions between the resin injection gates adjacent to each other are first to third regions,
The three resin injection gates are respectively provided at positions shifted from the circumferential center of the column portion to the circumferential one side so that the number of the pockets in the first to third regions is equal to each other.
At the center in the circumferential direction of the column portion furthest away from both ends of the first to third regions, a resin reservoir capable of storing the dissolved resin is provided, respectively.
The bearing cage manufacturing method according to claim 1, wherein a cross-sectional area of the communication portion of the resin reservoir communicating with the column portion is ¼ or less of a cross-sectional area of the resin injection gate.

Images