JP4186205B2 - Bearing with resin pulley - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a bearing with a resin pulley that is suitable for an idler bearing, a tensioner bearing, and the like that are used for adjusting belt tension and changing a traveling path in an automobile timing belt, an auxiliary machine driving belt, and the like.
[0002]
[Prior art]
Conventionally, in order to reduce the weight and reduce the cost of bearings used in auxiliary machinery driving belts for transmitting engine rotational power to automobile auxiliary machinery, the outer peripheral surface of the metal outer ring of the rolling bearing is used. In addition, a bearing with a resin pulley formed by integrally molding a pulley made of synthetic resin is used.
[0003]
An example of a resin pulley 10 of a conventional bearing with a resin pulley will be described with reference to FIGS. 1 and 2. The resin pulley 10 is provided between an inner diameter cylindrical portion 11 fixed to an outer ring of a rolling bearing (not shown), an outer diameter cylindrical portion 12 having a belt guide surface 13, and the inner diameter cylindrical portion 11 and the outer diameter cylindrical portion 12. The disc portion 14 and a plurality of reinforcing ribs 15 that are radially formed on both surfaces of the disc portion 14 at predetermined intervals.
[0004]
[Problems to be solved by the invention]
Conventionally, the resin pulley 10 is manufactured by injection molding of synthetic resin. That is, the rolling bearing or its outer ring is centered and fixed in the mold, and the mold cavity is filled with a molten resin via a resin injection gate and solidified, and then the mold is opened for molding.
[0005]
However, when the resin pulley 10 is injection-molded, the molten resin injected from each gate joins in the molding die, and a weld is generated at the joining portion. For example, a weld often occurs in the inner diameter cylindrical portion 11 that is in the vicinity of the outer ring of the rolling bearing on the end surface opposite to the gate side end surface.
[0006]
When a weld is generated in the inner cylindrical portion 11, a crack is generated in the resin pulley 10 starting from the weld portion due to a difference in linear expansion coefficient between the resin pulley 10 and the metal outer ring, and the resin pulley 10 is damaged. There was a problem.
[0007]
In particular, when the weld formation direction is substantially parallel to the direction of thermal expansion extending radially outward from the rolling bearing, cracks are likely to occur in the resin pulley 10.
[0008]
An object of the present invention is to provide a bearing with a resin pulley that can suppress the occurrence of cracks in the resin pulley starting from the weld portion and prevent the resin pulley from being damaged.
[0011]
[Means for Solving the Problems]
Claim 1 of the present invention is a resin pulley with bearings which is integrally molded resin pulley on the outer peripheral surface of the outer ring of the rolling bearing, the resin pulley, an inner diameter cylindrical portion for fixing the outer ring of the rolling bearing, An outer diameter cylindrical portion having a belt guide surface; a disk portion provided between the inner and outer diameter cylindrical portions; and a plurality of reinforcing ribs radially formed on the disk portion; A pair of gates respectively formed between the adjacent portion of the first reinforcing rib and the second and third reinforcing ribs sequentially adjacent to the first reinforcing rib are arranged in the circumferential direction of the resin pulley. They are arranged sequentially.
[0012]
According to the resin pulley with a bearing according to claim 1 of the present invention, the inner diameter of the cylindrical portion, and the adjacent portion of the first reinforcing rib, between the second and third reinforcing ribs sequentially adjacent to the first reinforcing rib By forming a pair of gates, the molten resin flowing in from each gate joins at the intersection of the second reinforcing rib and the inner cylindrical portion, and a weld is formed inclined with respect to the radial direction of the resin pulley. Is done. In this way, the weld formation direction is not substantially parallel to the direction of thermal expansion extending radially outward from the rolling bearing, and the weld area increases, so that the resin pulley and the metal Due to the difference in the coefficient of linear expansion from the outer ring, it is possible to suppress the occurrence of cracks in the resin pulley starting from the weld portion. In addition, since the weld is formed in the thick reinforcing rib portion, it is possible to further suppress the occurrence of cracks in the resin pulley.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to FIGS. The structure of the resin pulley 10 of the bearing with the resin pulley is the same as the example shown in FIGS.
[0014]
FIG. 3 shows a front view of a bearing 20 with a resin pulley formed by integrally molding the resin pulley 10 on the outer periphery of the rolling bearing 30. The rolling bearing 30 is composed of an inner ring 31, an outer ring 32, ball and roller rolling elements 33, and the like, and a resin pulley 10 is provided by fixing the inner cylindrical portion 11 to the outer ring 32. Reference numerals 40 and 41 denote gates formed on one end face of the inner diameter cylindrical portion 11 of the resin pulley 10.
[0015]
FIG. 4 shows a partially enlarged front view of the resin pulley 10. The gate 40 is formed in a portion adjacent to the first reinforcing rib 15 a of the inner diameter cylindrical portion 11. Further, the gate 41 is formed in the inner cylindrical portion 11 between the second reinforcing rib 15b and the third reinforcing rib 15c that are sequentially adjacent to the first reinforcing rib 15a in the clockwise direction. Similarly, the gates 40 and 41 are sequentially arranged at equal intervals in the circumferential direction of the resin pulley 10.
[0016]
FIG. 5 shows a cross-sectional view of the molding process of the resin pulley 10. The mold for molding the resin pulley 10 includes an upper mold 50 and a lower mold 51. The rolling bearing 30 is centered and fixed between the upper and lower molds 50 and 51, and the cavity around it is filled with molten resin.
[0017]
Here, 52 is a cavity for the inner diameter cylindrical portion 11, 53 is a cavity for the outer diameter cylindrical portion 12, 54 is a cavity for the disc portion 14, and 55 is a cavity for the reinforcing rib 15. Further, a gate hole 56 is opened in the cavity 52 for the inner diameter cylindrical portion corresponding to the formation place of the gates 40 and 41. Reference numeral 57 denotes a runner.
[0018]
When the molten resin is filled from the gate hole 56 through the runner 57 in the state where the rolling bearing 30 is set, the molten resin flows in the cavity 52 for the inner diameter cylindrical portion, and for the cavity 54 for the disk portion and the reinforcing rib. , And reaches the cavity 53 for the cylindrical portion of the outer diameter, and is filled in the cavities 52, 53, 54, and 55.
[0019]
As shown in FIG. 4, the molten resin filled from each gate hole 56 joins in the cavity at the intersection of the reinforcing rib 15 and the inner diameter cylindrical portion 11.
[0020]
That is, the molten resin filled from the gate hole 56 corresponding to the gate 40 flows left and right in the circumferential direction in the cavity 52 for the inner diameter cylindrical portion, and the cavity 54 for the disk portion and the adjacent first reinforcing rib. It spreads to the cavity 55 for reinforcement ribs corresponding to 15a.
[0021]
In addition, the molten resin filled from the gate hole 56 corresponding to the gate 41 flows in the left and right in the circumferential direction in the cavity 52 for the inner diameter cylindrical portion, and spreads to the cavity 54 for the disk portion. Further, in the reinforcing rib cavity 55 corresponding to the second reinforcing rib 15 b, the molten resin filled from the gate hole 56 corresponding to the gate 40 is merged. Since the fluidity of the molten resin is higher in the thick part of the cavity than in the thin part of the cavity, the molten resin easily flows in the cavity 55 portion for the reinforcing rib, and the flow of the molten resin changes, and the second It flows into the reinforcing rib cavity 55 corresponding to the reinforcing rib 15b. As a result, a weld 42 is formed at an intersection between the second reinforcing rib 15b and the inner diameter cylindrical portion 11 so as to be inclined with respect to the radial direction of the resin pulley 10.
[0022]
Similarly, the molten resin filled from the gate hole 56 corresponding to the gate 41 and the gate hole 56 corresponding to the next gate 40 are also filled at the intersection of the third reinforcing rib 15 c and the inner diameter cylindrical portion 11. The melted resin merged and inclined with respect to the radial direction of the resin pulley 10 forms a weld 43. Hereinafter, the welds 42 and 43 are formed so as to be sequentially inclined with respect to the radial direction of the resin pulley 10, that is, so as not to be substantially parallel to the thermal expansion direction P extending radially outward from the rolling bearing 30. .
[0023]
The welds 42 and 43 may be formed so as to be inclined with respect to the radial direction of the resin pulley 10 at the intersection between the reinforcing rib 15 and the inner diameter cylindrical portion 11, and as in the above-described embodiment, the inner diameter cylindrical portion. 11 is not limited to the gates 40 and 41 formed between the adjacent portions of the first reinforcing ribs 15a and the second and third reinforcing ribs 15b and 15c, respectively. The number can be arbitrarily selected.
[0024]
Moreover, in the said embodiment, although the gate 41 was formed in the center part between the 2nd and 3rd reinforcement ribs 15b and 15c, it should just be between the 2nd and 3rd reinforcement ribs 15b and 15c, In particular, it does not have to be formed at the center.
[0025]
【The invention's effect】
According to the bearing with a resin pulley of the present invention, it is possible to suppress the occurrence of cracks in the resin pulley starting from the weld portion and to prevent the resin pulley from being damaged.
[Brief description of the drawings]
FIG. 1 is a front view of a resin pulley.
2 is a cross-sectional view taken along the line II-II in FIG.
FIG. 3 is a front view of a bearing with a resin pulley in an embodiment of the present invention.
FIG. 4 is a partially enlarged front view of a resin pulley according to an embodiment of the present invention.
FIG. 5 is a cross-sectional view of a resin pulley molding process according to an embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Resin pulley 11 Inner diameter cylindrical part 12 Outer diameter cylindrical part 13 Belt guide surface 14 Disk part 15 Reinforcement rib 20 Bearing 30 with resin pulley Rolling bearing 31 Inner ring 32 Outer ring 33 Rolling elements 40, 41 Gates 42, 43 Weld

Claims (1)

A bearing with a resin pulley in which a resin pulley is integrally formed on the outer peripheral surface of an outer ring of a rolling bearing,
The resin pulley is radially formed on an inner diameter cylindrical portion fixed to the outer ring of the rolling bearing, an outer diameter cylindrical portion having a belt guide surface, a disk portion provided between the inner and outer diameter cylindrical portions, and the disk portion. A plurality of reinforcing ribs,
A pair of gates respectively formed between an adjacent portion of the one end surface of the inner diameter cylindrical portion with the first reinforcing rib and the second and third reinforcing ribs sequentially adjacent to the first reinforcing rib, A bearing with a resin pulley arranged sequentially in a circumferential direction of the resin pulley.

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