JP2012107703A - Cage for rolling bearing, method of manufacturing the same, and rolling bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inexpensively provide a cage having no void, having high strength and superior in dimensional accuracy, without requiring a separate mechanism exclusive to compression and deburring work of a pocket.SOLUTION: A molding metal mold for forming a cavity coincident with a cage shape and arranging a movable pin of sliding in the cavity in the cavity arranged in a proper place of a boundary surface corresponding to a cage annular ring part end surface of the cavity, is used. After filling the cavity and a dead space by injecting a melting resin composition in a state of forming the dead space between the tip of the movable pin and the boundary surface by pulling the movable pin, the tip of the movable pin is made to coincident with the boundary surface by moving the movable pin before solidifying the melting resin composition, a resin contraction quantity in solidification of becoming a void occurrence source is complemented, and next, the cage for a rolling bearing is manufactured by solidifying the melting resin composition still in a compressed state. The rolling bearing including the cage obtained in this way, is also provided.

Description

  The present invention relates to a rolling bearing cage made of synthetic resin and a method for manufacturing the same. Moreover, this invention relates to a rolling bearing provided with the said holder | retainer.

  In rolling bearings, in order to cope with rotation at high speed, a synthetic resin cage that is lightweight and excellent in flexibility is often used. A synthetic resin cage is generally manufactured by an injection molding method. The molten resin composition is injected and filled into a cavity of a molding die, and the molten resin composition is solidified by holding and cooling. . However, in a normal injection molding method, if the cage is thick, voids due to a difference in volume shrinkage due to a temperature difference between the inside and the outside are likely to occur during cooling. Therefore, in a large cage, the strength often decreases due to voids generated during molding.

  Normally, the holding pressure is increased to compensate for the shrinkage of the resin so as not to generate voids. However, if the holding pressure is increased unnecessarily, the mold clamping force will be lost to the injection pressure and mold opening will occur. Cause burr. Further, at a position far from the gate, sufficient pressure cannot be applied due to pressure loss, and generation of voids cannot be suppressed.

  For this reason, it has been proposed to devise the design of the cage to suppress the generation of voids. For example, in Patent Document 1, in a cage for a tapered roller bearing, by providing a meat stealing portion in the annular portion and the column portion, the cage is made thin overall and uniform in thickness, and the cooling rate is maintained in the cage. Uniform throughout, eliminating temperature differences and reducing voids. However, since the entire cage is thin, even if no void is generated, the strength of the cage itself is reduced, so that there is a limit to thinning.

  An injection compression molding method is also known as a method for suppressing the generation of voids without reducing the thickness. This injection compression molding method is a method in which the molding die is moved after injection filling and compression is applied to the resin. Unlike ordinary injection molding, a uniform high pressure is applied to the entire molded product without pressure loss. And thereby the generation of voids is suppressed. As the injection compression method, as shown in Patent Documents 2 to 4, the mold is held on the movable side just before the cavity coincides with the shape of the cage using the mold clamping mechanism of the molding machine, and the molten resin composition is put there. After the injection filling, a method for moving the movable side mold until the cavity matches the shape of the cage and applying compression, or another mechanism dedicated to compression as in Patent Documents 5 to 7, is provided. ) And the movable mold are completely clamped, and after injection filling, a method of performing compression by moving to another mechanism dedicated to compression is known.

Japanese Patent No. 3774706 JP-A-9-39046 JP-A-8-323813 JP 2005-231239 A Japanese Patent Publication No. 4-30329 Japanese Patent Laid-Open No. 6-24679 Japanese Patent Laid-Open No. 7-80894

  However, since the cage has pockets for holding the rolling elements, it is generally difficult to mold by the injection compression method as described above. That is, in order to form a pocket, the cavity must be completely clamped until it matches the shape of the cage, and then the molten resin composition must be injection-filled and solidified. However, as described above, since the cavity is not completely clamped when the resin is filled for compression, the molten resin composition enters the portion corresponding to the pocket of the cavity. Since the resin is not completely discharged, burrs may remain in the pocket of the obtained cage, or the pocket may not be formed in some cases. For this reason, a deburring process or the like is separately required, resulting in an increase in cost.

  In addition, since the molten resin composition that has entered the portion that does not match the shape of the original cage is compressed, a large pressure is applied to the molding die during compression, which may cause damage to the molding die. .

  Furthermore, in the method of adding another mechanism dedicated to compression, a device, equipment, and process of another mechanism are required, resulting in an increase in cost.

  The present invention has been made in view of such a situation. A cage having no voids, high strength, and excellent dimensional accuracy can be obtained at a low cost without requiring a separate mechanism dedicated to compression or a deburring operation of a pocket. The purpose is to provide.

In order to achieve the above object, the present invention provides the following.
(1) A method of manufacturing a rolling bearing cage made of synthetic resin by an injection molding method,
A molding metal in which a cavity matching the shape of the cage is formed, and a movable pin that slides in the cavity is provided in a cavity provided at an appropriate position on the boundary surface corresponding to the end surface of the cage annular portion of the cavity. After using the mold and filling the cavity and the void by injecting the molten resin composition in a state where a void is formed between the tip of the movable pin and the boundary surface by pulling the movable pin, Before the molten resin composition is solidified, the movable pin is moved so that the tip of the movable pin coincides with the boundary surface, and the resin shrinkage at the time of solidification that becomes a void generation source is complemented. A method for producing a cage for a rolling bearing, wherein the molten resin composition is solidified as it is.
(2) The method for manufacturing a rolling bearing cage according to (1), wherein the cage is for a roller bearing, and the cavity is provided to face the cage pillar.
(3) After the resin is cured, the molding die is opened, and the movable pin is moved beyond the boundary surface to release the cage, (1) or (2) above A method for manufacturing a cage for a rolling bearing.
(4) A rolling bearing retainer obtained by the method according to any one of (1) to (3) above.
(5) A rolling bearing comprising the rolling bearing cage according to (4) above.

  According to the present invention, the molten resin composition injected into the cavity is compressed by the movement of the movable pin, and the resin shrinkage at the time of solidification that becomes a void generation source is complemented, so that a high-strength cage can be obtained. . In addition, warpage, sink marks, deformation, and the like can be prevented, and dimensional accuracy is improved. Furthermore, since the cavity matches the shape of the cage, the molten resin composition does not enter the pocket, eliminating the need for deburring the pocket and further eliminating the need for a separate mechanism dedicated to compression. Can be manufactured at low cost.

It is a perspective view which shows an example of the retainer for tapered roller bearings. (A) It is a partial cross section figure which shows the metal mold | die used for manufacture of the retainer for tapered roller bearings of FIG. 1, and the figure which shows the state when injecting and filling a molten resin composition, (B) Filling It is a figure which shows a state when solidifying a molten resin composition. It is a figure which shows another example about arrangement | positioning of the cavity and movable pin of the metal mold | die shown in FIG. It is a figure which shows another example about arrangement | positioning of the cavity of a shaping die shown in FIG. 2, and a movable pin. It is a perspective view which shows an example of the crown type cage for ball bearings. FIG. 6 is a partial cross-sectional view showing a molding die used for manufacturing the crown type cage of FIG. 5, and shows a state when the molten resin composition is injection-filled; (B) a filled molten resin composition; It is a figure which shows the state when making it solidify. It is a perspective view which shows an example of the retainer for cylindrical roller bearings. It is a perspective view which shows an example of the retainer for angular ball bearings. It is a perspective view which shows the other example of the retainer for angular ball bearings. It is the upper side figure and side view which show an example of the retainer for needle roller bearings.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a perspective view showing a tapered roller bearing retainer 1 which is an example of a rolling bearing retainer, and has a shape in which upper and lower annular portions 10A and 10B are connected by a plurality of column portions 11. A pocket 12 for holding a tapered roller (not shown) is formed by the two annular portions 10A, 10B and the adjacent column portions 11, 11.

  In order to manufacture this tapered roller bearing retainer 1, in the present invention, a molding die 20 shown in FIG. 2 is used. FIG. 2 is a partial cross-sectional view showing the molding die 20 corresponding to the side surface of the tapered roller bearing retainer 1, but when the mold is clamped, the cavity matches the shape of the tapered roller bearing retainer 1 21 is formed. That is, the cavity 21 includes an upper annular cavity 21A corresponding to the upper annular part 10A, a lower annular cavity 21B corresponding to the lower annular part 10B, and a columnar cavity corresponding to the pillar part 11. 21C is connected to the upper annular cavity 21A, the lower annular cavity 21B, and the adjacent columnar cavity 21C, 21C corresponding to the pocket 12 of the tapered roller bearing retainer 1. A pocket portion 22 is formed. Furthermore, the molding die 20 is provided with a cavity 26 extending in a direction perpendicular to the boundary surface 25 at an appropriate position of the boundary surface 25 with the lower annular cavity 21B of the cavity 21. Is provided with a movable pin 30 that slides in the vertical direction in the figure.

  At the time of molding, as shown in (A), the upper annular hollow portion 21A, the lower annular hollow portion 21B and the columnar hollow portion 21C of the cavity 21 are held for the tapered roller bearing in the same manner as in a normal injection molding method. The mold 20 is clamped so as to match the shape of the vessel 1. At that time, the movable pin 30 is pulled, that is, lowered in the example shown in the figure, and a void 27 is formed between the tip 30a of the movable pin 30 and the boundary surface 25 of the lower annular cavity 21B of the cavity 21. . Then, with the void 27 formed, the molten resin composition is injected and filled through a gate (not shown). Thereby, in addition to the cavity 21, the void 27 is filled with the molten resin composition.

  Next, before the molten resin composition is solidified, as shown in (B), the movable pin 30 is moved upward in the figure so that the tip 30a is placed on the boundary surface 25 of the lower annular cavity 21B of the cavity 21. Match. Thereby, the molten resin composition filled in the space 27 is pushed into the cavity 21, and the molten resin composition is compressed inside the cavity 21.

  In the production of the normal tapered roller bearing retainer 1, voids are likely to occur at the connecting portion between the upper annular cavity 21A or the lower annular cavity 21B and the columnar cavity 21C. In FIG. 2A, the void is schematically indicated by “◯”. However, according to the above method, the resin shrinkage (void) that becomes a void generation source is supplemented by pushing the molten resin composition in the void 27 into the cavity. Accordingly, the volume of the void 27 is set in consideration of the resin shrinkage.

  And it hold | maintains in this compression state, and solidifies a molten resin composition through a holding pressure and a cooling process.

  Thereafter, the tapered roller bearing retainer 1 is obtained by opening the mold. However, the tapered roller bearing retainer 1 can be easily released from the molding die 20 by further raising the movable pin 30. it can. Since the obtained tapered roller bearing retainer 1 is obtained by filling the molten resin composition only into the cavity 21 matching the shape of the retainer and solidifying it, no burrs are generated in the pocket 12, and the dimensional accuracy is improved. Will be expensive.

  In the above, the molten resin composition is not limited, and for example, a polyamide, polyphenylene sulfide resin, polyimide resin, polyether ether ketone resin and a fiber reinforcing material such as glass fiber, carbon fiber, potassium titanate whisker, etc. Used. Moreover, in order to suppress the thermal deterioration at the time of shaping | molding and use, you may add an iodide type | system | group heat stabilizer and an amine heat stabilizer independently, or both. Furthermore, in order to improve impact resistance, rubber-based materials such as ethylene propylene non-diene rubber (EPDM) may be blended.

  Further, the number of the cavities 26 is not limited and may be one, but by providing the cavities 26 at a plurality of places, voids are eliminated over the entire cage. For example, as shown in FIG. 3, a cavity 26 can be provided at an intermediate position of the width of each pocket portion 22.

  In the above description, the cavity 26 is provided at an intermediate position of the width of the pocket portion 22. However, as shown in FIG. 4, the cavity 26 is preferably provided so as to face the columnar empty portion 21 </ b> C. As shown in FIG. 2 (A), voids are likely to occur at the connecting portion between the upper annular cavity 21A or the lower annular cavity 21B and the columnar cavity 21C. By providing them so as to face each other, voids are hardly generated.

  Further, although not shown, the cavity 26 may be provided on the upper annular cavity 21 </ b> A side of the cavity 21.

  The manufacturing method of the present invention can be applied to various cages in addition to the tapered roller bearing cage 1. For example, the present invention can be applied to the production of a crown type cage 1A for ball bearings as shown in FIG. In this crown-type cage 1A, pillars 11A are erected at equal intervals on one side of an annular base 10D, and a ball (not shown) is formed by a pair of adjacent pillars 11A, 11A. A pocket 12A for holding is formed. Each column portion 11A includes a pair of claws 11X and 11Y on both sides of the flat portion 11T.

  In such a crown type cage 1A, the column portion 11A is the thickest portion, and voids are likely to occur in the central portion of the column portion 11A. Therefore, in the present invention, as shown in FIG. 6, a cavity 21 that matches the shape of the cage is formed, and the cavity 26 is located at an intermediate position between the claw-shaped empty portions 11x and 11y corresponding to the claw 11X and 11Y of the column portion 11A. And the forming mold 20 provided with the movable pins 30 is used. In FIG. 6A, the void is schematically indicated by “◯”. In the same manner as described above, after the movable pin 30 is pulled as shown in (A) and the molten resin composition is injected and filled with the void 27 formed, the movable pin 30 is flattened as shown in (B). The molten resin composition in the space 27 is pushed into the cavity 21 by moving to the boundary surface 11t corresponding to the portion 11T, and the resin shrinkage that becomes a void generation source is complemented. Next, by solidifying while maintaining this state, a crown-shaped cage 1A without voids is obtained.

  In the molding die 20 used for manufacturing the crown type cage 1A, the cavity 26 may be provided on the boundary surface 10d corresponding to the base portion 10D.

  In addition, for example, FIG. 7 shows an example of a cylindrical roller bearing retainer 1B. For the cylindrical roller bearing retainer 1B, it is necessary to use a radial draw die (split mold) for mold release. If the molten resin composition is injected and filled without completely clamping the cavity until it matches the shape of the cage, the molten resin composition enters the split surface in addition to the pocket portion of the cavity. Therefore, in the conventional injection compression method, deburring work is required at the pocket 12B and the part corresponding to the split surface. However, according to the present invention, deburring work becomes unnecessary in addition to preventing voids.

  Further, it can be applied to the manufacture of cages for angular ball bearings as shown in FIGS. 8 and 9 and cages for needle roller bearings as shown in FIG. 10, and cavities having shapes corresponding to the respective cages are provided. And using a molding die provided with a movable pin at an appropriate position on the boundary surface corresponding to the end surface of the annular portion, preferably at an intermediate position between the pockets or facing the column portion, and By performing injection filling, holding and solidification of the same molten resin composition, in addition to preventing voids, a pocket deburring operation is not required.

  The present invention provides a rolling bearing including a cage manufactured as described above. All the cages have no voids and high strength, and have excellent durability and high reliability.

DESCRIPTION OF SYMBOLS 1 Retainer 10A, 10B for tapered roller bearings Annular part 11 Pillar part 12 Pocket 20 Molding die 21 Cavity 25 Interface 26 Cavity 27 Cavity 30 Movable pin

Claims (5)

A method of manufacturing a roller bearing cage made of synthetic resin by an injection molding method,
A molding metal in which a cavity matching the shape of the cage is formed, and a movable pin that slides in the cavity is provided in a cavity provided at an appropriate position on the boundary surface corresponding to the end surface of the cage annular portion of the cavity. After using the mold and filling the cavity and the void by injecting the molten resin composition in a state where a void is formed between the tip of the movable pin and the boundary surface by pulling the movable pin, Before the molten resin composition is solidified, the movable pin is moved so that the tip of the movable pin coincides with the boundary surface, and the resin shrinkage at the time of solidification that becomes a void generation source is complemented. A method for producing a cage for a rolling bearing, wherein the molten resin composition is solidified as it is.   2. The method of manufacturing a cage for a rolling bearing according to claim 1, wherein the cage is for a roller bearing, and the cavity is provided to face the cage column portion.   3. The rolling bearing cage according to claim 1, wherein after the resin is cured, the molding die is opened, and the movable pin is moved beyond the boundary surface to release the cage. 4. Production method.   A rolling bearing retainer obtained by the method according to any one of claims 1 to 3. A rolling bearing comprising the rolling bearing cage according to claim 4.

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