JP2014001756A - Retainer for conical roller bearing, and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin retainer for a conical roller bearing that can be stably and continuously molded and has excellent circularity, and a manufacturing method thereof.SOLUTION: A retainer for a conical roller bearing comprising: a small-diameter annular section; a large-diameter annular section; plural column sections coupling the small-diameter annular section and the large-diameter annular section and arranged at predetermined intervals in a circumferential direction; and plural pocket sections defined by the small-diameter annular section, the large-diameter annular section and the plural column sections and respectively housing conical rollers is injection-molded by a die for molding a retainer. At least three resin injection gates are arranged at predetermined intervals in the circumferential direction at a portion of the die for molding the retainer corresponding to an inner periphery of the small-diameter annular section of the retainer for the conical roller bearing, and an under-cut section is formed across an entire circumference.

Description

  The present invention relates to a tapered roller bearing retainer and a method for manufacturing the same.

  As shown in FIG. 2, the tapered roller bearing retainer includes a small-diameter annular portion 3, a large-diameter annular portion 5, and a small-diameter annular portion 3 and a large-diameter annular portion 5 that are connected in the circumferential direction. A plurality of column portions 7 arranged at a predetermined interval, a small-diameter ring portion 3, a large-diameter ring portion 5, and a plurality of column portions 7, each of which contains a plurality of tapered rollers (not shown). What is provided with the pocket part 9 is known.

  Such a tapered roller bearing retainer 1 (hereinafter sometimes simply referred to as a “retainer”) has been conventionally manufactured by injection molding. As the mold for injection molding, a two-plate type mold is mainly used, and a melt of a resin composition in which a reinforcing fiber material or the like is blended with a thermoplastic resin or a thermoplastic resin from one or a plurality of gates is used as a mold. After pouring into the mold and cooling and solidifying the melt, the mold is opened, and the cage remaining in the movable mold is ejected by an ejector mechanism such as an ejector pin. Note that the gate installation position and the number of installations are appropriately set according to the size of the cage, the mold structure, the amount of resin material used for parts other than the cage (mainly sprue and runner), and the like.

  The circularity of the cage is important for a bearing that incorporates the cage thus formed to rotate normally. If the roundness of the cage is poor, the cage may come into contact with the race rings (outer ring, inner ring) or excessively collide with the rollers during rotation of the bearing, thereby hindering rotation of the bearing. Therefore, various measures have been studied and implemented in order to secure the roundness of the cage and improve the roundness.

  For example, in Patent Document 1, in a resin cage manufactured by injection molding using a mold and a manufacturing method thereof, the mold has three or four gates, and the cage thickness is relative to the cage outer diameter. It is described that the ratio is 0.05 to 0.15, and the outer diameter of the cage is 10 mm or more. By configuring in this way, the fluidity of the molten resin and the orientation of the glass fiber, etc. are improved, and the strain and deformation at the time of solidification are dispersed in the circumferential direction by the three or four welds, and the perfect circle of the cage We are trying to improve the degree.

  Moreover, in patent document 2, in the manufacturing method of a rolling bearing, while injection-molding so that the number of pockets of a cage may become an even number, the gate of the metal mold | die used for the said injection molding is the number of pockets on the inner diameter side of a cage. It is described that half the number is provided on the circumference equally. With this configuration, a large number of welds are formed on the circumference of the molded product at equal intervals, the shape of the molded product is made uniform, and the roundness of the cage is improved.

  Further, in Patent Document 3, in the method of manufacturing a synthetic resin cage for roller bearings, when a molten resin is injected into a mold cavity through a gate to mold the cage, the cage is equally divided in the circumferential direction of the cage. It is described that injection molding is performed by disposing a gate for injecting a molten resin in the central portion of the axial height of all the column portions arranged in the above. As a result, joints that can be made at positions where the molten resin has flowed equidistantly are formed at equidistant positions in the circumferential direction, and the conditions when the molten resin material in all the column parts is cooled and solidified are made uniform. It aims to improve the roundness.

  Further, in order to improve the strength of the corner portion of the cage pocket, the following measures have been studied and implemented for the gate of the resin cage for the tapered roller bearing. For example, Patent Document 4 discloses a method for manufacturing a cage for a tapered roller bearing in which a die gate is provided for each pocket at an intermediate position between adjacent column portions on the inner peripheral surface of a small-diameter annular portion. Further, Patent Document 5 discloses a tapered roller bearing retainer in which a gate portion into which a molten resin is injected is formed on an extension of each column portion of a small-diameter annular portion.

Japanese Patent Laying-Open No. 2005-083406 JP 2004-068861 A JP 2002-005176 A JP 2007-321926 A JP 2006-070926 A

  By the way, when manufacturing a holder | retainer by injection molding like the patent documents 1-5 mentioned above, when a metal mold | die is opened, a holder | retainer may be taken by a fixed mold | type. In such a case, it is necessary to stop the molding and remove the cage from the fixed mold, which makes it impossible to continuously mold the cage.

  In order to solve such a problem, a technique is known in which a mold release undercut portion is provided on the movable mold side so that the molded cage remains reliably in the movable mold having a protruding mechanism. However, when the cage is protruded from the movable mold, the undercut portion is forcibly removed, so that the cage is deformed, and the roundness is deteriorated.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a resin cage for a tapered roller bearing that can be stably continuously molded and has excellent roundness, and a method for manufacturing the same. There is to do.

The above object of the present invention can be achieved by the following constitution.
(1) a small-diameter annular part,
A large-diameter annulus,
A plurality of pillars that connect the small-diameter annular part and the large-diameter annular part and are arranged at predetermined intervals in the circumferential direction;
A plurality of pocket portions defined by the small-diameter annular portion, the large-diameter annular portion, and the plurality of pillar portions, each containing a tapered roller;
A method of manufacturing a tapered roller bearing retainer, wherein a cage for a tapered roller bearing is injection-molded by a cage molding die,
At least three resin injection gates are arranged at predetermined intervals in the circumferential direction on a portion of the cage molding die corresponding to the inner peripheral surface of the small diameter annular portion of the cage for the tapered roller bearing, And the undercut part is formed over the perimeter, The manufacturing method of the retainer for tapered roller bearings characterized by the above-mentioned.
(2) The undercut portion is located in an axial direction between the resin injection gate and an axially outer end portion of a portion corresponding to the inner peripheral surface of the small diameter annular portion ( A method for producing a cage for a tapered roller bearing according to 1).
(3) The method for manufacturing a tapered roller bearing retainer according to (1) or (2), wherein an outer diameter of the large-diameter annular portion of the tapered roller bearing retainer is 120 mm or more.
(4) A tapered roller bearing retainer manufactured by the method for manufacturing a tapered roller bearing retainer according to any one of (1) to (3).

According to the invention described in (1) above, since the resin injection gate is installed at a portion corresponding to the inner peripheral surface of the small-diameter annular portion, the flow length and volume of the sprue portion and the runner portion can be minimized. The mold variation and material cost can be reduced, and the mold structure can be made relatively simple.
In addition, since at least three resin injection gates are provided, three or more welds are formed in the annular portion of the cage, and it is possible to avoid elliptical deformation that extremely deteriorates the roundness of the annular portion. .
In addition, since a plurality of resin injection gates are arranged (equally arranged) at predetermined intervals in the circumferential direction, welds are also formed equally, and deformation is concentrated on a part of the annular portion of the cage. It is possible to prevent the roundness from greatly deteriorating.
Furthermore, the position where the undercut part is provided is close to the resin injection gate, so the pressure loss when filling the resin is small, and the original roundness is relatively stable and corresponds to the good inner peripheral surface of the small-diameter ring part. By setting it as the portion to be used, the roundness of the entire cage can be kept good even if it is affected by the deformation caused by forcible removal when protruding from the movable mold.

  According to the invention described in (2) above, since the undercut portion is located between the resin injection gate and the axially outer end portion of the portion corresponding to the inner peripheral surface of the small-diameter annular portion, the holding The small-diameter annular portion of the vessel can be released more quickly from the deformed state that accompanies unreasonable removal when protruding. Furthermore, it is possible to prevent the undercut portion from interfering with the edge of the mold gate.

  According to the invention described in (3) above, a cage having a large size in which the flow length of the molten resin is long and variations in molding are likely to occur, particularly a cage having an outer diameter of a large-diameter annular portion of 120 mm or more. However, it is possible to ensure good roundness.

It is a perspective view of the retainer for tapered roller bearings concerning the embodiment of the present invention. It is a perspective view of the conventional retainer for tapered roller bearings.

  Hereinafter, an embodiment of a manufacturing method of a retainer for tapered roller bearings concerning the present invention is described in detail.

  As shown in FIG. 1, a tapered roller bearing retainer 1 (hereinafter sometimes simply referred to as “retainer”) manufactured by the manufacturing method of the present invention includes a small-diameter annular portion 3 and a large-diameter circle. A plurality of (18 in FIG. 1) column portions 7 that connect the ring portion 5, the small-diameter ring portion 3 and the large-diameter ring portion 5 and are arranged at predetermined intervals in the circumferential direction, and a small-diameter ring A plurality of (18 in FIG. 1) pocket portions 9 that are defined by the portion 3, the large-diameter annular portion 5, and the plurality of column portions 7, each of which accommodates a tapered roller (not shown).

  The cage 1 is a two-plate type cage molding die (not shown. Hereinafter, it may be simply referred to as “mold”), which is a fixed type and a movable type corresponding to the shape of the cage 1. And manufactured by injection molding.

  A portion of the mold corresponding to the inner peripheral surface of the small-diameter annular portion 3 of the cage 1, that is, the outer peripheral surface of the movable mold, is provided with a plurality of resin injection gates at predetermined intervals (equal distribution) in the circumferential direction (FIG. 1). In the figure, reference numeral 11 denotes a mark generated by cutting the resin solidified in the gate from the molded product, that is, a gate mark. In the present embodiment, a total of nine resin injection gates are provided for every other pocket portion 9, and the middle in the circumferential direction of each of the nine pocket portions 9 and the middle in the axial direction of the small-diameter annular portion 3. Is located. The number of these resin injection gates is not particularly limited as long as it is at least three or more. Further, the gate size and the gate system are not particularly limited, and may be appropriately selected according to the shape of the cage 1 and the mold structure. For example, a submarine gate, a side gate, an overlap gate, or the like is used as the gate system. .

  And the cage | basket 1 inject | pours the thermoplastic resin or the melt of the resin composition which mix | blended the reinforcing fiber material etc. with the thermoplastic resin from the resin injection gate of the mold mentioned above, and after cooling and solidifying the melt, It is obtained by opening the mold and projecting the cage 1 remaining in the movable mold by an ejecting mechanism such as an ejector pin. Examples of the resin material include polyamide resins such as 46 nylon and 66 nylon, polybutylene terephthalate, polyferlen salside (PPS), polyether ether ketone (PEEK), polyether nitrile (PEN), and the like. A resin composition to which 50 wt% reinforcing fiber (for example, glass fiber or carbon fiber) is added is used.

  Here, the mold of the present embodiment has a portion corresponding to the inner peripheral surface of the small-diameter annular portion 3 of the cage 1, that is, an undercut portion (in FIG. Reference numeral 13 is a convex portion formed by cooling and solidifying the resin composition filled in the undercut portion. The undercut portion is formed between the resin injection gate and the axially outer end portion of the portion corresponding to the inner peripheral surface of the small diameter annular portion 3 in the axial direction. Therefore, the convex portion 13 of the cage 1 is also formed at the axially outer end portion (lower end portion in FIG. 1) of the inner peripheral surface of the small diameter annular portion 3. Note that the shape of the undercut portion is a shape that protrudes from a portion corresponding to the inner peripheral surface of the small-diameter annular portion 3 of the mold (that is, a concave portion is formed on the inner peripheral surface of the small-diameter annular portion 3 of the cage 1. However, it is preferable to have a concave shape as in this embodiment because the mold processing is easy.

As described above, according to the manufacturing method of the tapered roller bearing retainer of the present embodiment, the resin injection gate is installed at a portion corresponding to the inner peripheral surface of the small diameter annular portion 3 of the mold. The flow length and volume of the sprue portion and the runner portion can be minimized, the molding variation and material cost can be reduced, and the mold structure can be made relatively simple.
Further, since at least three resin injection gates are provided, three or more welds are formed in the small-diameter or large-diameter annular portions 3 and 5 of the cage 1, and the roundness of the small-diameter or large-diameter annular portions 3 and 5 is formed. Can be avoided.
Further, since the plurality of resin injection gates are arranged (equally arranged) at a predetermined interval in the circumferential direction, the welds are also formed equally, and the small-diameter or large-diameter annular portions 3, 5 of the cage 1 are formed. It is possible to prevent the roundness from greatly deteriorating due to the concentration of deformation in a part of the surface.
Furthermore, since the position where the undercut portion is provided is close to the resin injection gate, the pressure loss at the time of resin filling is small, the original roundness is relatively stable, and the good inner peripheral surface of the small-diameter annular portion 3 is provided. By adopting the corresponding portions, the roundness of the cage 1 as a whole can be kept good even if it is influenced by deformation due to unreasonableness when protruding from the movable mold.

  Further, since the undercut portion is located between the resin injection gate and the axially outer end portion of the portion corresponding to the inner peripheral surface of the small diameter annular portion 3, the small diameter annular portion 3 of the cage 1 is It is possible to release more quickly from the deformed state due to unreasonableness at the time of protrusion. Furthermore, it is possible to prevent the undercut portion from interfering with the edge of the mold gate.

  In addition, the present invention is suitable even for a cage having a large size in which the flow length of the molten resin is long and variation in molding is likely to occur, particularly a cage having an outer diameter of the large-diameter annular portion of 120 mm or more. It is possible to ensure circularity.

Example 1
Next, in the same manufacturing method as that of the above-described embodiment, the cage 1 (large-diameter annular portion outer diameter: Φ120 mm, small-diameter annular portion outer diameter: Φ106 mm, width: 42 mm, pocket number: 18, gate number: 9 ) 50 pieces were injection molded continuously. As the material, a resin composition in which 25% by mass of glass fiber was blended with polyamide 66 resin was used. And the outer diameter roundness of the large diameter annular part 5 and the small diameter annular part 3 of these 50 cages 1 was measured, and the average value and the maximum value were obtained. The measurement results are shown in Table 1.

(Example 2)
The same manufacturing method as that of the above-described embodiment, and cage 1 having a specification different from that of Example 1 (large-diameter annular portion outer diameter: Φ140 mm, small-diameter annular portion outer diameter: Φ122 mm, width: 50 mm, number of pockets: 21 The number of gates: 3) 50 pieces were continuously injection molded. The resin injection gates are arranged in three equal positions (every six column portions) at an extension position in the middle of the column portion 7 in the portion corresponding to the inner peripheral surface of the small-diameter annular portion 3 of the mold. . As the material, a resin composition in which 30% by mass of glass fiber was blended with polyamide 46 resin was used. And the outer diameter roundness of the large diameter annular part 5 and the small diameter annular part 3 of these 50 cages 1 was measured, and the average value and the maximum value of these were obtained. The measurement results are shown in Table 1.

(Comparative Example 1)
The undercut portion is the same as that of the above-described embodiment except that the undercut portion is provided not on the portion corresponding to the inner peripheral surface of the small-diameter annular portion 3 but on the portion corresponding to the inner peripheral surface of the large-diameter annular portion 5. Cage 1 having the same specifications as in Example 1 in the manufacturing method (outer diameter of large ring portion: Φ120 mm, outer diameter of small ring portion: Φ106 mm, width: 42 mm, number of pockets: 18, number of gates: 9) 50 The pieces were continuously injection molded. Similarly to Example 1, the material used was a resin composition in which 25% by mass of glass fiber was blended with polyamide 66 resin. And the outer diameter roundness of the large diameter annular part 5 and the small diameter annular part 3 of these 50 cages 1 was measured, and the average value and the maximum value were obtained. The measurement results are shown in Table 1.

(Comparative Example 2)
A cage 1 having the same specifications as in Example 1 except that no undercut portion is provided, and a cage 1 having the same specifications as in Example 1 (outer diameter of large diameter annular portion: Φ120 mm, outer diameter of small diameter annular portion: Φ106 mm) , Width: 42 mm, number of pockets: 18, number of gates: 9) Attempts were made to continuously injection mold 50 pieces. However, the cage 1 remained in the fixed mold during the continuous molding, and 50 continuous moldings were not possible. After the molding was stopped and the cage 1 was removed from the fixed mold, 50 continuous injection moldings were attempted again. However, the cage remained in the stationary mold again before reaching 50, and continuous molding was not possible. . In addition, the material used the resin composition which mix | blended 25 mass% of glass fibers with the polyamide 66 resin similarly to Example 1. FIG.

  As shown in Table 1, in the cage 1 of Examples 1 and 2 in which an undercut portion is provided in a portion corresponding to the inner peripheral surface of the small-diameter annular portion 3 of the mold, the outer diameter of the large-diameter annular portion 5 is increased. The roundness of the diameter and the roundness of the outer diameter portion of the small-diameter annular portion 3 are substantially the same value, and the roundness of the cage 1 as a whole is kept good. On the other hand, in the cage of Comparative Example 1 in which the undercut portion is provided in the portion corresponding to the inner peripheral surface of the large diameter annular portion 5 of the mold, the roundness of the outer diameter of the large diameter annular portion 5 is extremely large. As a result, the maximum roundness of the entire cage also becomes twice or more the values of the first and second embodiments, and it is understood that the roundness of the entire cage also deteriorates. As described above, according to the manufacturing method of the present invention, it has been clarified that it is possible to provide a cage that can be stably continuously formed and is excellent in roundness.

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

DESCRIPTION OF SYMBOLS 1 Retainer for tapered roller bearing 3 Small diameter annular part 5 Large diameter annular part 7 Column part 9 Pocket part 11 Gate mark 13 Convex part

Claims (4)

A small diameter ring part,
A large-diameter annulus,
A plurality of pillars that connect the small-diameter annular part and the large-diameter annular part and are arranged at predetermined intervals in the circumferential direction;
A plurality of pocket portions defined by the small-diameter annular portion, the large-diameter annular portion, and the plurality of pillar portions, each containing a tapered roller;
A method of manufacturing a tapered roller bearing retainer, wherein a cage for a tapered roller bearing is injection-molded by a cage molding die,
At least three resin injection gates are arranged at predetermined intervals in the circumferential direction on a portion of the cage molding die corresponding to the inner peripheral surface of the small diameter annular portion of the cage for the tapered roller bearing, And the undercut part is formed over the perimeter, The manufacturing method of the retainer for tapered roller bearings characterized by the above-mentioned. The undercut portion is located in an axial direction between the resin injection gate and an axially outer end portion of a portion corresponding to the inner peripheral surface of the small diameter annular portion. The manufacturing method of the cage for tapered roller bearings of description. The method for manufacturing a tapered roller bearing retainer according to claim 1 or 2, wherein an outer diameter of the large-diameter annular portion of the tapered roller bearing retainer is 120 mm or more. A tapered roller bearing retainer manufactured by the method for manufacturing a tapered roller bearing retainer according to any one of claims 1 to 3.

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