JPS62200021A - Bearing - Google Patents

Abstract

PURPOSE:To secure a bearing at the specified accuracy by means of injection molding alone, by opening a gate in a bridging part bridging two-strip paired rings, and molding these rings. CONSTITUTION:Two-strip rings 5 of plastics are molded on an outer circumferential (setting) surface 7 of the ball bearing constituted of an outer ring 1, an inner ring 2, a cage 3 and a ball 4, but these elements are embedded in an annular groove 6 at the base, and projected out of the outer circumferential surface 7. And, both these rings 5 are connected with each other by a bridging part 13 constituted of synthetic resin burying a depression part 11 in depth H installed on the outer circumferential surface 7. These rings 5 are molded by means of injection molding of synthetic resin, between a metal mold 10 and the outer circumferential surface 7 via a runner 8 and a gate 9, by this metal mold 10. And, the gate 9 is opened at the center of the bridging part 13. With this constitution like that, a bearing at the specified accuracy is securable by means of injection molding alone, without entailing any polishing work afterward.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a structure for mounting a bearing to an axle box.

(Prior art) Bearings that support motorcycle crankshafts, alternator shafts, etc. are assembled into aluminum axle boxes, and due to the difference in thermal expansion between them, "
A change in fit occurs.In order to absorb this change in fit and always securely fix the bearing in the axle box, a synthetic resin ring is provided around the outer circumference of the bearing, and the shaft is inserted through the ring. The structure is such that the box supports the bearing (Special Publication Act 1976-1976).
(See Japanese Utility Model Publication No. 86 and Japanese Utility Model Application Publication No. 53-79953).

FIG. 6 shows a ball bearing using the above-mentioned conventional technique. Outer shaft 1. Domestic import 2. A ball bearing consisting of a retainer 3 and balls 4 has its outer ring 1 clamped and fixed by an axle box (not shown). A resin ring 5 is the molding. The ring 5 fills an annular groove 6 provided in the outer ring 1 and protrudes from the outer peripheral surface 7 of the outer shaft 1 by a predetermined amount. Two grooves 6 and two rings 5 are provided at intervals in the axial direction.

The ball bearing is attached to the axle box by elastically deforming the protrusion of the ring 5, and a small gap is formed between the outer peripheral surface 7 of the outer ring 1 and the inner surface of the axle box. Since the elastically deformed ring 5 changes its deformation amount in accordance with changes in the "fit", the ball bearing is always securely fixed to the axle box.

The ring 5 may be formed by placing the entire ball bearing in a mold 10, as shown in FIG.

Only the outer ring 1 is placed in a mold 10 and molded around the outer periphery of the outer ring 1 by injection molding a synthetic resin. 8 is a runner and 9 is a gate. The gates 9 are provided at a plurality of locations (usually 4 to 6 gates) on each ring 5 so that the ring 5 is formed uniformly over its entire circumference. In addition,
In this example, a submarine gate is used as the gate 9, and gate cutting is automatically performed during mold release.

(Problems to be Solved by the Invention) Incidentally, the outer circumferential dimension of the ring 5 is required to be accurate, but this is essentially not possible with conventional injection molding methods.

That is, the ring 5 causes "sink" as shown in FIG. 6(a) due to shrinkage due to its solidification, but this "sink" does not occur uniformly over the entire circumference of the ring 5. In particular, there is a difference between the gate part and the weld part, which causes unevenness.

The "fit" is not uniform over the entire circumference.

Furthermore, the degree of dimensional accuracy depends not only on the precision of the mold but also on the injection method of the synthetic resin. In order to improve the roundness of the ring 5, a plurality of gates 9 are provided at equal intervals in the circumferential direction, but if a submarine gate is used and the gates are cut by tearing them off during demolding, as shown in FIG. The gate portion 9a becomes convex.

Furthermore, if the fit between the outer ring 1 and the mold 10 is not appropriate, or if there is a misalignment between the grooves 6 of the outer ring 1 and the grooves of the mold 10, burrs will occur. There is a difference in injection pressure between the parts where there is no surface and uneven thickness occurs, which also causes a decrease in roundness.

In order to eliminate the above-mentioned drawbacks, it is necessary to perform a polishing process after injection molding to improve the accuracy of the outer circumferential dimension of the ring 5, but this is not necessary in the present invention.

The purpose of this is to make it possible to obtain a predetermined precision only by injection molding.

(Means for Solving the Problems) For the above purpose, the present invention provides two grooves on the mounting surface (outer circumferential surface 7) of the bearing to the axle box, in addition to a pair of annular grooves 6, a bridge bridging them. A portion 13 is provided, and a gate 9 is provided opposite the center of the bridging portion 13. Further, the annular groove 12 for forming the ring protrusion provided in the mold 10 is narrower than the annular groove 6 provided in the mounting surface (outer peripheral surface 7).

(Function) By the synthetic resin injected into the space (mainly the annular grooves 6 and 12) formed between the mold 10 and the mounting surface of the bearing,
Two rings 5 are formed, but they are bridged by a bridge section 13. This bridge section 13 has a gate section 9a.
is formed and protrudes, but since the outer diameter of the bridge portion 13 is smaller than the outer diameter of the ring 5, the apex of the gate portion 9a does not protrude beyond the ring 5. Also, mold 1
The width of the annular groove 12 is narrower than the annular groove 6 provided on the mounting surface.

Even if the position of the mold 10 is slightly shifted, the annular groove 12 faces the annular groove 6 without being offset, so that no burrs are generated.

(Embodiment) FIGS. 1 and 2 show a first embodiment of the present invention. Outer ring 1, inner ring 2. Retainer 3. Two rings 5 made of synthetic resin are molded on the outer circumferential (mounting) surface 7 of the ball bearing composed of balls 4, and they are arranged in an annular groove 6.
The base portion is buried in and protrudes from the outer circumferential surface 7.

As shown in an enlarged view in FIG. 1(a), both rings 5 are connected by a bridge section 13 made of synthetic resin that fills a depression 11 with a depth h provided on the outer circumferential surface 7. . Further, the protruding portion of the ring 5 is formed to have an arcuate cross section. Note that the depth h is selected to be about 0.2+nm at the minimum. In this case, the height is set to be approximately 0.1 mm lower than the height of the protrusion.

The ring 5 is molded by injection molding using a mold 10 shown in FIG. That is, a runner 8. The synthetic resin is injection molded through the gate 9. The submarine gate 9 opens at the center of the bridge section 13.

Since the annular groove 12 of the mold 10 has an arcuate cross-section, the protrusion of the ring 5 has an arcuate cross-section. Further, the width of the annular groove 12 is 0.1 mm wider than the width a of the annular groove 6.
Even if the position of the mold 1o is slightly shifted, since these molds face each other and constitute the outer mold and the inner mold of the ring 5.

If it is within the difference between both ri, both grooves 6 and 12 will not be offset, and no beams will occur due to this.

Synthetic resin injected from submarine gate 9 is in depression 1
1 into the annular grooves 6 and 12 to form the ring 5, but even if a "sink" occurs at that time, since the ring 5 does not have a direct gate part 9a, it flows uniformly over the entire circumference. It becomes ``sink''.

Does not affect roundness. Furthermore, since the gate portion 9a is formed on the bridge portion 13 and does not protrude beyond the ring 5, it does not reduce the mounting accuracy when mounting the bearing.

Furthermore, the arcuate cross-sectional shape of the protrusion of the ring 5 is the shape of the mold 1.
This makes it possible to forcefully remove the material from the "o" position and prevent the shape from deforming in the axial direction. Further, the assembly work of the bearing can be facilitated.

FIG. 3 shows a second embodiment of the invention. In this example, four rings 5 are provided.

The four rings 5 are divided into two sets of two adjacent rings, and each set is connected by a separate bridge section 13.

FIG. 4 shows a third embodiment. In this example, the outer circumferential surface 7 of the outer ring 1 is not provided with a depressed portion 11. Instead, a depression is provided in the mold 10 to form the bridging part 13.

FIG. 5 shows an example in which the present invention is applied to a bearing that receives thrust loads. In this example, the axial end face 14 of the outer shaft 1 is used as the mounting surface, so the ring 5 is protruded from there.
A bridging portion 13 also communicates between the two rings 5.

(Effects) As described above, the present invention molds the ring by opening the gate in the bridging part that bridges a pair of two rings.As a result, no gate part remains on the ring itself, and as a result, it is difficult to form a ring. There is no reduction in accuracy and the number of gates can be halved. In addition, even if a "sink" occurs, since the gate is not provided on the ring itself, it will be uniform over the entire circumference and will not reduce the roundness. Since the width is narrower than the width of the annular groove on the mounting surface, no burrs will be generated even if there is a slight misalignment of the mold, and there will be no deterioration in accuracy due to this.

Therefore, a bearing with a predetermined accuracy can be obtained by simply injection molding without requiring subsequent polishing.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a first embodiment of the present invention, FIG. 1(a) is an enlarged view of the main part of FIG. 1, and FIG. 2 is a sectional view showing the molding process of the first embodiment. 3, 4, and 5 are cross-sectional views of the second, third, and fourth embodiments of the present invention. FIG. 6 is a sectional view showing the prior art, FIG. 6 ( ) is an enlarged view of the main part thereof, FIG. 7 is a sectional view showing the molding process, and FIG. 8 is a front view showing the prior art. 5...Ring 6...Annular groove 7...
Outer peripheral surface (mounting surface) 9... Gate 9a... Gate part 10... Mold 12... Annular groove
13... Bridge part patent applicant Koyo Seiko Co., Ltd. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 6 (Q) Figure 8

Claims (2)

[Claims] (1) A bearing in which a ring made of synthetic resin is molded in a protruding manner on the mounting surface of the bearing for the axle box, wherein the mounting surface is provided with two annular grooves, and both rings have two annular grooves, A mold having an annular groove having a width narrower than the annular groove is formed by injection molding between the annular groove and a synthetic resin injection gate is provided facing the center of the recessed part. bearings. (2) The bearing according to claim 1, wherein the cross-sectional shape of the protruding portion of the ring is arcuate.