JP7516051B2 - Insert bearing and manufacturing method thereof, sintered bearing suitable for insert bearing, sintered insert part and manufacturing method thereof, sintered part suitable for sintered insert part - Google Patents

Description

The present invention relates to an insert bearing that integrates a sintered bearing and an exterior part and a manufacturing method thereof, a sintered bearing suitable for an insert bearing, an insert sintered part and a manufacturing method thereof, and a sintered part suitable for an insert sintered part.

Sintered bearings are made by impregnating the interior of the sintered body with lubricating oil in advance, and the oil seeps out to lubricate the friction surfaces through the pumping action caused by the rotation of the shaft and thermal expansion due to frictional heat. Since sintered bearings can be used for long periods of time without lubrication, they are widely used as bearings for rotating shafts in automobiles, home appliances, audio equipment, etc.
In order to incorporate such sintered bearings into structures such as automobiles, they are integrated with exterior components such as housings by insert molding. In this case, radial and thrust loads act on the sintered bearing, so it is necessary to prevent both rotation relative to the exterior component and axial removal.

For example, Patent Document 1 discloses a sintered bearing (sintered part) having bottomed grooves formed in the outer peripheral surface at positions that do not coincide with each other in the axial direction, the bottomed grooves extending from both end faces to each end face and partway along the axial direction. It is described that when a resin part (exterior part) is integrally molded onto the outer peripheral surface of the sintered bearing by insert molding, the resin gets into the bottomed grooves, preventing rotation and axial falling off.
Also, Patent Document 2 discloses a sintered bearing (sintered part) in which an axially extending groove and a circumferentially extending enlarged diameter part are formed on the outer circumferential surface of the sintered bearing (sintered part), with the groove part interrupting the circumferential extension of the enlarged diameter part. When a resin part is integrally molded on the outer circumferential surface of the sintered bearing by insert molding, the resin gets into the groove part, preventing the sintered bearing from rotating relative to the resin part, and the enlarged diameter part is integrated so as to bite into the resin part, preventing the sintered bearing from coming loose in the axial direction.

JP 2003-159720 A JP 2003-193113 A

When insert-molding a sintered part such as a sintered bearing into a resin part, a space (cavity) is formed on the outer periphery of the sintered part placed in a molding die, and molten resin is injected into the cavity to fill it. At this time, in order to cover the outer periphery of the sintered part with the resin part, a cavity is formed around the outer periphery of the sintered part with both end faces abutted against the molding die.
However, because the injection pressure acts on the molten resin filling the cavity, the molten resin may penetrate into the contact surface between the sintered part and the molding die, forming a thin resin film on both end surfaces of the sintered part. If a resin film is formed on both end surfaces of the sintered part, it may not only spoil the appearance, but also cause interference with other parts.

The present invention was made in consideration of these circumstances, and aims to integrate a sintered part, such as a sintered bearing, with an exterior part, such as a resin part, by insert molding, without forming a film on at least one end face of the sintered part.

The method for producing an insert bearing of the present invention includes a sintered bearing forming step of forming a sintered bearing by powder molding, and an insert molding step of forming an insert bearing in which an exterior part is integrated with the outer periphery of the sintered bearing,
In the sintered bearing forming step, a large diameter portion having an outer diameter larger than both end portions is formed on an outer periphery of the sintered bearing, and a groove or a protrusion is formed along an axial direction on an outer periphery of the large diameter portion,
The insert molding process includes a mold assembly process in which the outer peripheral surfaces of the tip ends of both ends of the sintered bearing are abutted circumferentially against the inner peripheral surface of an insert molding die, and the base ends of the both ends and the periphery of the large diameter portion are covered with the insert molding die at intervals to form a cavity on the outer periphery of the sintered bearing, and a filling process in which, after the mold assembly process, the cavity is filled with molten material that will become the exterior part.

The insert bearing of the present invention has a sintered bearing and an exterior part molded integrally with the outer periphery of the sintered bearing, and the outer periphery of the sintered bearing is formed with a large diameter part having an outer diameter larger than both ends, and a groove or protrusion is formed along the axial direction on the outer periphery of the large diameter part, and the exterior part is formed in a shape that embeds the base end and the large diameter part at both ends of the sintered bearing except for the tip end.

A sintered bearing suitable for this insert bearing has a large diameter portion on the outer periphery that is larger in outside diameter than both ends, and grooves or ridges are formed on the outer periphery of the large diameter portion along the axial direction.

According to the present invention, the sintered bearing and the exterior part such as a resin part are prevented from rotating by the grooves or ridges of the sintered bearing, and are integrated in a state where they are prevented from coming off in the axial direction by the large diameter part. In addition, since the base end and the large diameter part of both ends of the sintered bearing are formed in a shape that embeds them, except for the tip ends, the end faces of both ends of the sintered bearing are prevented from being covered in a film-like shape by the material of the exterior part.

In one embodiment of the sintered bearing, the groove or ridge is formed over the entire length of the large diameter portion. Alternatively, the groove or ridge may be formed from one end face of the large diameter portion to partway along the length.

In one embodiment of the sintered bearing, tapered portions may be formed at both ends, the outer diameter of which gradually increases toward the large diameter portion.
In the insert molding process, the inner peripheral surface of the insert molding die comes into contact with the outer peripheral surfaces of both ends of the sintered bearing, but because the insert molding die comes into contact with the tapered portions, it is difficult for a gap to form between the insert molding die and the sintered bearing. This makes it possible to reliably prevent leakage of the molten material due to the pressure applied when the molten material is filled.

The method for producing an insert sintered part of the present invention includes a sintered part forming step of forming a sintered part by powder molding, and an insert molding step of forming an insert sintered part in which an exterior part is integrated with the outer periphery of the sintered part,
In the sintered part forming step, a groove or a protrusion is formed on an outer periphery of the sintered part except for at least one end portion thereof,
The insert molding process includes a mold assembly process in which the outer peripheral surface of the one end is abutted circumferentially against the inner peripheral surface of an insert molding mold, and the grooves or protrusions in the area excluding the one end are covered with the insert molding mold at intervals to form a cavity on the outer periphery of the sintered part, and a filling process in which, after the mold assembly process, the cavity is filled with molten material that will become the exterior part.

The insert sintered part of the present invention has a sintered part and an exterior part molded integrally with the outer periphery of the sintered part, and grooves or protrusions are formed on the outer periphery of the sintered part except for at least one end, and the exterior part is formed in a shape that embeds the outer periphery of the sintered part except for the tip of the one end.

Sintered parts suitable for this insert sintered part have grooves or protrusions formed on the outer periphery of the area excluding at least one end.

According to the present invention, the sintered part and the exterior part such as the resin part are prevented from rotating by the grooves or protrusions of the sintered part and are integrated. In addition, the sintered part is formed in such a way that the outer periphery is embedded except for the tip part at least on one end, so that at least one end face of the sintered part is prevented from being covered in a film-like shape by the material of the exterior part.

In one embodiment of the insert sintered part, the sintered part is made of a sintered bearing, and a large diameter part having an outer diameter larger than that of the one end part is formed on the outer periphery of the sintered bearing, and the large diameter part is formed with at least one of the groove or ridge along the axial direction on the outer periphery of the large diameter part, and the groove or ridge along the radial direction of the large diameter part.

In one embodiment of the insert sintered part, the large diameter portion is formed in the area of the outer periphery of the sintered part excluding both ends, and the exterior part is formed in a shape that embeds the base end portion excluding the tip end portions of both ends and the large diameter portion.

The sintered bearing of the present invention has a large diameter portion formed on the outer periphery of an area excluding at least one end, the large diameter portion having an outer diameter larger than that of the at least one end, and at least one of a groove or ridge along the axial direction on the outer periphery of the large diameter portion and a groove or ridge along the radial direction on one end face of the large diameter portion is formed on the large diameter portion.

In one embodiment of the sintered bearing, the groove or ridge is formed along the axial direction over the entire length of the outer circumferential surface of the large diameter portion. Alternatively, the groove or ridge may be formed along the axial direction from one end surface of the large diameter portion to partway along the length.

In one embodiment of the sintered bearing, at least one of the ends may be formed with a tapered portion whose outer diameter gradually increases toward the large diameter portion.
In this case, in the insert molding step, the inner peripheral surface of the insert molding die comes into contact with the outer peripheral surface of at least one end of the sintered bearing, but because the insert molding die comes into contact with the tapered portion, it is difficult for a gap to form between the insert molding die and the sintered bearing. This makes it possible to reliably prevent leakage of the molten material due to the pressure applied when the molten material is filled.

In the present invention, a sintered part such as a sintered bearing and an exterior part are prevented from rotating by grooves or protrusions in the sintered part, and are integrated with each other. Furthermore, the sintered part and the exterior part can be integrated by injection molding without forming a film made of the material of the exterior part on at least one end face of the sintered part.

1 is a vertical cross-sectional view showing an insert bearing according to a first embodiment of the present invention. FIG. 2 is a perspective view of a sintered bearing used in the insert bearing of FIG. 1 . FIG. 3 is a vertical sectional view of the sintered bearing of FIG. 2 . FIG. 3 is an end view of the sintered bearing of FIG. 2 as viewed from one side in the axial direction. 4 is a flowchart showing a manufacturing process of the insert bearing of the first embodiment. FIG. 2 is a vertical cross-sectional view showing a state in which a molded body is being formed in a molding process. FIG. 2 is a vertical cross-sectional view showing a state in which a sintered body is being straightened in a straightening process (left half) and a state in which the sintered body has been removed from the straightening die (right half). FIG. 2 is a vertical cross-sectional view showing a state after a mold clamping step in an injection molding step. FIG. 11 is a perspective view of a sintered bearing used in the insert bearing of the second embodiment of the present invention. FIG. 10 is a vertical cross-sectional view of the sintered bearing of FIG. FIG. 10 is an end view of the sintered bearing of FIG. 9 as viewed from one side in the axial direction. FIG. 11 is a vertical cross-sectional view showing a state in which the sintered body is being straightened in the second straightening step, in which the left half shows a state in which the sintered body has been removed from the straightening die, and the right half shows a state in which the sintered body has been removed from the straightening die. FIG. 11 is a perspective view of a sintered bearing used in the insert bearing of the third embodiment of the present invention. FIG. 14 is a vertical cross-sectional view of the sintered bearing of FIG. 13. FIG. 14 is an end view of the sintered bearing of FIG. 13 as viewed from one side in the axial direction. FIG. 2 is a vertical cross-sectional view showing a state in which a sintered body is being straightened in a straightening process (left half) and a state in which the sintered body has been removed from the straightening die (right half). FIG. 11 is a longitudinal sectional view of a sintered bearing used in an insert bearing according to a fourth embodiment of the present invention. FIG. 18 is an end view of the sintered bearing of FIG. 17 as viewed from one side in the axial direction. FIG. 13 is a longitudinal sectional view of a sintered bearing used in an insert bearing according to a fifth embodiment of the present invention. FIG. 20 is an end view of the sintered bearing of FIG. 19 as viewed from one axial side. FIG. 2 is a vertical cross-sectional view showing a state after a mold clamping step in an injection molding step. FIG. 13 is a longitudinal sectional view of a sintered bearing used in an insert bearing according to a sixth embodiment of the present invention. FIG. 23 is an end view of the sintered bearing of FIG. 22 as viewed from one axial side. FIG. 13 is an enlarged longitudinal sectional view showing a portion of an insert bearing according to a seventh embodiment of the present invention. FIG. 25 is a perspective view of a sintered bearing used in the insert bearing of FIG. 24 . 25 is a vertical cross-sectional view showing a state during a mold clamping step in an injection molding process in the manufacturing method of the insert bearing of FIG. 24. FIG. 13 is an enlarged longitudinal cross-sectional view showing a portion of an insert bearing according to an eighth embodiment of the present invention. FIG. 28 is a perspective view of a sintered bearing used in the insert bearing of FIG. 27. FIG. 13 is an enlarged longitudinal cross-sectional view showing a portion of an insert bearing according to a ninth embodiment of the present invention. FIG. 30 is a perspective view of a sintered bearing used in the insert bearing of FIG. 29 . 12 is an enlarged longitudinal cross-sectional view showing a portion of an insert bearing according to a tenth embodiment of the present invention. FIG. FIG. 32 is a perspective view of a sintered bearing used in the insert bearing of FIG. 31 . FIG. 23 is an enlarged longitudinal cross-sectional view showing a portion of an insert bearing according to an eleventh embodiment of the present invention. FIG. 34 is a perspective view of a sintered bearing used in the insert bearing of FIG. 33 .

Hereinafter, embodiments of the present invention will be described. In each of the following embodiments, a resin part is integrated with a sintered bearing by injection molding. Therefore, in the embodiments, the exterior part of the present invention is a resin part, and the insert molding process is an injection molding process.
In the following embodiments, a sintered bearing is exemplified as the sintered part, and an insert sintered bearing is exemplified as the insert sintered part.

[First embodiment]
First, an insert bearing according to the first embodiment will be described. In the first to sixth embodiments described below, a large diameter portion is provided at approximately the center of the outer periphery of the sintered bearing used in the insert bearing, and the large diameter portion has an outer diameter larger than both ends of the sintered bearing.
As shown in FIG. 1, this insert bearing 1 has a cylindrical sintered bearing 10 formed from a sintered body of metal powder, and a resin part 20 (corresponding to the exterior part of the present invention) molded integrally with the outer periphery of the sintered bearing.
2 to 4, the sintered bearing 10 has a bearing hole 11 formed in the center in a penetrating state, and is formed in a stepped shape with an outer diameter larger in the axially intermediate portion than in both end portions 12. In this embodiment, both small-diameter end portions 12 are formed to have the same outer diameter and length (height), and a large-diameter portion 13 in the middle is formed to have a length (height) excluding both end portions 12.

Additionally, a plurality of grooves 14 extending from one end to a midway point in the axial direction are formed at intervals in the circumferential direction on the outer periphery of the large diameter portion 13. In this embodiment, ten grooves 14 shorter than half the length (height) of the large diameter portion 13 are formed at intervals of 36°. The deepest portions of these grooves 14 are formed as a concave arc surface, and both sides of the concave arc surface are connected to the outer periphery of the large diameter portion 13 by convex arc surfaces.
In this embodiment, a radially protruding ridge 15 is formed along the circumferential direction at the axially intermediate position of the large diameter portion 13 .

On the other hand, the resin part 20 is an exterior part that constitutes a part of, for example, an automobile part, a housing of a home appliance, a mechanical part, etc. to which the sintered bearing 10 is attached, and is provided so that the tip ends of both ends 12 are exposed and the base ends (root parts) of both ends 12 and the large diameter part 13 are embedded in the outer periphery of the sintered bearing 10 as shown in FIG. 1. That is, in the resin part 20, the bearing holder 21 is fixed integrally to the outer periphery of the sintered bearing 10, and the bearing holder 21 is formed to a height smaller than the overall height of the sintered bearing 10, and the entire large diameter part 13 is embedded from the midpoint of the axial direction of both ends 12 of the sintered bearing 10. Therefore, both end faces of the large diameter part 13 are covered by the bearing holder 21. Reference numeral 22 denotes a bracket that is connected to other parts.

A method for manufacturing the insert bearing 1 thus formed (a method for manufacturing a sintered insert part) will now be described.
5, the insert bearing 1 is manufactured through a sintered bearing formation process (sintered part formation process) in which a sintered bearing 10 is formed by powder molding, and then an injection molding process (corresponding to the insert molding process of the present invention) in which the sintered bearing 10 formed in the sintered bearing formation process is placed in an injection molding die (corresponding to the insert molding die of the present invention) and a resin part 20 is formed integrally with the outer periphery of the sintered bearing 10 by injection molding. Each process will be described in detail below.

<Sintered bearing forming process>
The sintered bearing formation process includes a molding process for forming a green body 10' that will become the sintered bearing 10, a sintering process for sintering the green body 10' to form a sintered body (not shown), and a straightening process (sizing process) for straightening the sintered body.

(Molding process)
6, a molding die 40 for forming the molded body 10' includes a die 42 having a circular through hole 41 formed therein, and a core rod 43 disposed in the through hole 41. A first upper punch 44 and a first lower punch 45, and a second upper punch 46 and a second lower punch 47 are provided in upper and lower pairs from the outside between the die 42 and the core rod 43. These punches 44 to 47 are formed in a concentric cylindrical shape with the core rod 43 at the center.

Then, powder is filled into the space formed by the die 42, core rod 43, first lower punch 45, and second lower punch 47, and compressed by the upper and lower punches 44 to 47 to form the green body 10'. At this time, by making the distance between the first punches 44, 45 smaller than the distance between the second punches 46, 47, a stepped green body 10' is formed with a large diameter portion 13' on the outer periphery. In addition, a bearing hole 11' is formed in a through state by the core rod 43.

(Sintering process)
The resulting molded body 10' is heated to sinter the powder, forming a sintered body.

(Straightening process)
The sintered body is subjected to sizing using a sizing die 50. In this sizing process, the outer shape is finished to the final dimensions, and a groove 14 is formed on the outer periphery of the large diameter portion 13.
7, a first upper punch 54 and a first lower punch 55, and a second upper punch 56 and a second lower punch 57 are provided in upper and lower pairs from the outside between a die 52 in which a circular through hole 51 is formed and a core rod 53 placed in the through hole 51. These punches 54 to 57 are formed in a concentric cylindrical shape with the core rod 53 at the center.

In addition, a convex portion 58 for forming the groove 14 is formed on the upper end of the first lower punch 55. The sintered body is then pressed axially by the first punches 54, 55 and the second punches 56, 57 while being pushed between the die 52 and the core rod 53, thereby correcting the sintered body. In this case, the first upper punch 54 and the first lower punch 55 correct the outer peripheral surface of the large diameter portion of the sintered body to a midpoint in the height direction. Therefore, after correction, the sintered body (sintered bearing) 10 has a groove 14 on the outer peripheral portion of the large diameter portion 13, as well as a convex streak 15 along the circumferential direction at a midpoint in the height direction.

<Injection molding process>
The sintered bearing 10 formed as described above is integrally molded with the resin part 20 by an injection molding process. This injection molding process includes a mold clamping process (corresponding to the mold assembly process of the present invention) in which the sintered bearing 10, with a cavity 61 formed on the outside, is placed in an injection molding die 60, and an injection process (corresponding to the filling process of the present invention) in which molten resin (corresponding to the molten material of the present invention) that will become the resin part is injected into the cavity 61.

<Mold clamping process>
8, the injection mold 60 has a fixed die 62 and a movable die 63, between which the sintered bearing 10 is held, and a cavity 61 is formed in which molten resin is filled on the outer periphery of the sintered bearing 10. The sintered bearing 10 is held in a fitted state in recesses 64, 65 of the fixed die 62 and the movable die 63 up to midway along the length of both ends, so that the inner circumferential surfaces of the recesses 64, 65 abut over the entire circumference of the outer circumferential surfaces of both ends 12 of the sintered bearing 10. The cavity 61 has a bearing retaining space 66 formed to surround the outer periphery of the sintered bearing 10, and a communicating portion 67 communicates with the bearing retaining space 66. The large diameter portion 13 of the sintered bearing 10 and the base ends (root portions) of both ends 12 near the large diameter portion 13 are exposed in the bearing retaining space 66 of the cavity 61. A sprue 68 for supplying molten resin is connected to the cavity 61 via a gate 69 , and a plunger (not shown) for injecting the molten resin is connected to the sprue 68 .

<Injection process>
As shown in Fig. 8, molten resin is injected into a cavity 61 of a clamped injection molding die 60. At this time, injection pressure acts inside the cavity 61, but because the tip ends of both ends 12 of the sintered bearing 10 are fitted into the recesses 64, 65 of the fixed die 62 and the movable die 63 and the tip ends of both ends 12 are not exposed inside the cavity 61, the injection pressure acts on the outer surface of the sintered bearing 10 excluding the tip ends of both ends 12. For this reason, the molten resin does not leak out to both end faces of the sintered bearing 10. Even if the molten resin does get into the gap between the contact surfaces of the sintered bearing 10 and the die 60, it will only leak slightly around the outer circumferential surfaces of both ends 12 of the sintered bearing 10.

As shown in FIG. 1, the insert bearing 1 has a central portion including the large diameter portion 13 at both ends 12 of the sintered bearing 10, excluding the tip portion, surrounded by the resin part 20, and the sintered bearing 10 and the resin part 20 are prevented from rotating by the groove 14, and are integrated in a state where they are prevented from coming off in the axial direction by the large diameter portion 13. Furthermore, because no resin film is formed on both end surfaces of the sintered bearing as described in the prior art, the appearance is not marred and interference with other parts is suppressed.

[Second embodiment]
9 to 11 show a sintered bearing 100 used in an insert bearing of the second embodiment. The sintered bearing 100 of this embodiment does not have the protruding rib 15 of the large diameter portion 13 that was provided in the sintered bearing 10 of the first embodiment. In the second embodiment and the subsequent embodiments, elements common to the first embodiment are given the same reference numerals to simplify the explanation.
In this second embodiment, the straightening process is performed in two stages. That is, in the first straightening, grooves 14 are formed in the outer periphery of the large diameter portion 13 by the method described in the first embodiment (first straightening). In this first straightening, ridges 15 are also formed in the outer periphery of the large diameter portion 13 together with the grooves 14. In the second straightening, the ridges 15 are removed (second straightening). In this second straightening, the inner periphery of the die is formed into a cylindrical surface, and the outer periphery of the large diameter portion 13 is straightened by this cylindrical surface, thereby finishing the outer periphery of the large diameter portion 13 into a cylindrical surface.

12 shows a correction die 70 used in the second correction. In this correction die 70, a first upper punch 74 and a first lower punch 75, and a second upper punch 76 and a second lower punch 77 are provided in an upper and lower pair from the outside between a die 72 in which a circular through hole 71 is formed and a core rod 73 disposed in the through hole 71. However, unlike the correction die 50 (see FIG. 7) used in the first correction, the inner peripheral surface of the cylindrical die 72 forms the outer peripheral surface of the large diameter portion 13, and the upper end of the first lower punch 75 abuts against the end surface of the large diameter portion 13.
After this second correction, injection molding can be performed in the same manner as in the first embodiment, to obtain an insert bearing (not shown) in which the central portion, including the large diameter portion 13 at both ends 12 of the sintered bearing 100 but excluding the tip portions, is surrounded by a resin part 20 (see Figure 1).

As with the first embodiment, this insert bearing is integrated with the sintered bearing 100 and the resin part 20, which are prevented from rotating by the groove 14 and from coming loose in the axial direction by the large diameter part 13. In addition, no resin film is formed on either end of the sintered bearing 100, so the appearance is not marred and interference with other parts is suppressed.

[Third embodiment]
13 to 15 show a sintered bearing 101 used in an insert bearing of the third embodiment. In the sintered bearing 101 of this embodiment, a plurality of grooves 141 are formed in the outer periphery of the large diameter portion 13 along the axial direction over the entire length of the large diameter portion 13 to both end faces of the large diameter portion 13.
When manufacturing this sintered bearing 101, a straightening die 80 shown in Fig. 16 is used in the straightening step after the molding step and sintering step of the sintered bearing process. This straightening die 80 has a first upper punch 84 and a first lower punch 85, and a second upper punch 86 and a second lower punch 87 arranged in an upper and lower pair from the outside between a die 82 in which a circular through hole 81 is formed, and a core rod 83 placed in the through hole 81. In this case, a plurality of protrusions 88 penetrating along the axial direction are formed at intervals in the circumferential direction on the inner peripheral surface of the through hole 81 of the die 82, and grooves 89 into which the protrusions 88 of the die 82 are slidably fitted are formed at intervals in the circumferential direction on the outer periphery of the first upper punch 84 and the first lower punch 85.

By placing the sintered body in this correction die 80 and correcting it, grooves 141 are formed at intervals in the circumferential direction on the outer periphery of the large diameter portion 13 .
As in the other embodiments, the insert bearing formed from this sintered bearing 101 has the sintered bearing 101 and the resin part 20 prevented from rotating by the groove 141 and integrated in a state prevented from coming loose in the axial direction by the large diameter portion 13, and since no resin film is formed on both end faces of the sintered bearing 101, the appearance is not marred and interference with other parts is suppressed.

[Fourth embodiment]
17 and 18 show a sintered bearing 102 used in an insert bearing of the fourth embodiment. As in the third embodiment, the sintered bearing 102 of this embodiment has a plurality of grooves 142 formed in the large diameter portion 13 of the sintered bearing 102 along the axial direction over the entire length of the large diameter portion 13 to both end faces of the large diameter portion 13, but in this embodiment, the cross-sectional area of the grooves 142 is larger than that of the grooves 141 of the third embodiment, and therefore these grooves 142 are formed in a molding process rather than a straightening process.

That is, although not shown in the figures, the molding die is configured like the corrective die 80 of the third embodiment, a plurality of ridges penetrating along the axial direction are formed at intervals in the circumferential direction on the inner periphery of the through hole of the die, and grooves into which the ridges of the die are slidably fitted are formed at intervals in the circumferential direction on the outer periphery of the first lower punch and the first upper punch. The ridges of the die form grooves 142 on the outer periphery of the large diameter part of the compact.
Then, the molded body having groove 142 formed on the outer periphery of large diameter portion 13 is subjected to a sintering process and a straightening process to form sintered bearing 102, which is then injection molded to surround large diameter portion 13 and integrated with resin part 20 to produce the insert bearing.

[Fifth embodiment]
19 and 20 show a sintered bearing 103 used in an insert bearing of the fifth embodiment. In this embodiment, the sintered bearing 103 is not formed with a straight cylindrical shape at both ends 121, but is formed with a tapered shape in which the outer diameter gradually decreases from the large diameter portion 131 toward both ends. The gradient θ of the tapered surface of both ends (tapered portions) 121 is formed to, for example, 15° (taper angle 30°). In addition, the groove 143 formed in the large diameter portion 131 is formed halfway along the length of the large diameter portion 131, and the open tip is formed on the tapered surface (end surface of the large diameter portion 131). In addition, a convex rib 15 is formed along the circumferential direction at the center position in the height direction of the large diameter portion 131.

This sintered bearing 103 is formed by the same sintered bearing forming process as in the first embodiment. The tapered surfaces of both ends 121 are formed during the molding process, but if the gradient θ is small, they may be formed during the straightening process. In the injection molding process, the inner surfaces of the recesses 641, 651 of the fixed die 62 and the movable die 63 are formed into tapered surfaces at the same angle as both ends 121 of the sintered bearing 103 by the injection molding die 600 shown in FIG. 21 during the mold clamping process, and the fixed die 62 and the movable die 63 are clamped together by the tapered fit of both ends 121 of the sintered bearing 103 into the recesses 641, 651.

In this mold clamped state, the tapered surfaces of both end portions 121 of the sintered bearing 103 and the tapered surfaces of the recesses 641, 651 of the injection molding die 600 are fitted together, so that molten resin is less likely to enter between the tapered surfaces compared to the abutment state between straight cylindrical surfaces as in the first embodiment, and resin leakage from not only both end faces but also the outer circumferential surfaces (tapered surfaces) of both end portions 121 can be reliably prevented.
The protruding ridge 15 formed at the intermediate position of the large diameter portion 131 may be removed in the second correction by performing the correction process in two steps, as in the second embodiment.

Sixth Embodiment
22 and 23 show a sintered bearing 104 used in an insert bearing of the sixth embodiment. In the sintered bearing 104 of this embodiment, like the sintered bearing 103 of the fifth embodiment, both end portions 121 are tapered so that the outer diameter gradually decreases from the large diameter portion 131 toward both ends. The gradient of this tapered surface is, for example, 15° (taper angle 30°). Furthermore, the groove 144 formed in the large diameter portion 131 is formed over the entire length of the large diameter portion 131, and both ends in the open state are each formed into a tapered surface.

Although not shown in the figures, it is also possible to make the cross-sectional area of the groove larger than that of the sintered bearing of the sixth embodiment, as in groove 142 shown in FIG. 18, and to form the groove in the molding process rather than in the straightening process.

[Seventh embodiment]
In the seventh embodiment to the eleventh embodiment described below, an example is described in which a large diameter portion is provided in a region excluding one end of the outer periphery of a sintered bearing used in an insert bearing, and this large diameter portion has an outer diameter larger than that of one end of the sintered bearing.
Fig. 24 shows a vertical cross section of a portion (half of the sintered bearing 105 and a portion of the resin part 20A) of the insert bearing 1A (insert sintered part) of the seventh embodiment, and Fig. 25 shows the sintered bearing 105 used in the insert bearing 1A. Note that Fig. 24 shows only a portion of the insert bearing 1A, but the overall shape is the same as the shape shown in Fig. 1.
The sintered bearing 105 of this embodiment differs from the sintered bearings 10, 101 to 104 of the first to sixth embodiments in that it has a large diameter portion 135 that extends to the other end 123. In other words, the end face of the large diameter portion 135 and the end face of the other end 123 are located on the same plane and are continuous.

The outer periphery of the sintered bearing 105 is embedded in the resin part 20A except for the tip of one end 122 (the end continuing to the end face of the end 122). In other words, the resin part 20A exposes the tip of one end 122 in the outer periphery of the sintered bearing 105, and embeds the base end (root part) and large diameter part 135 of one end 122. In other words, in the resin part 20A, the bearing holder 21A is fixed integrally to the outer periphery of the sintered bearing 105, and the bearing holder 21A is formed at approximately the same height as the entire height of the sintered bearing 105, and embeds the entire large diameter part 13 from the midpoint in the axial direction of one end 122 of the sintered bearing 105. Therefore, both end faces of the large diameter part 13 are covered by the bearing holder 21.

The end 122 on one side of the sintered bearing 105 is tapered, with the outer diameter gradually decreasing from the large diameter portion 135 toward the end 122. The gradient of this tapered surface is, for example, 15° (taper angle 30°). The groove 145 formed in the large diameter portion 135 is formed over the entire length of the large diameter portion 131, and both ends in the open state are each formed into a tapered surface. The shape of this groove 145 is approximately the same as the groove 141 shown in FIG. 13.

The manufacturing method for such an insert bearing 1A is substantially the same as the manufacturing method for the sintered bearing 10 of the first embodiment, but there are some differences in the shapes of the injection molding dies used in the mold clamping step and the injection molding step.
FIG. 26 is a vertical cross-sectional view showing a state during a mold clamping step in an injection molding process in a manufacturing method of the insert bearing 1A.

26, the injection mold 60A has a fixed mold 62A and a movable mold 63A, and the sintered bearing 105 is held between the fixed mold 62A and the movable mold 63A, and a cavity 61A is formed in which molten resin is filled on the outer periphery of the sintered bearing 105. The sintered bearing 105 is held in a fitted state up to the middle position in the length direction of one end 122 in the recess 64A of the fixed mold 62A, so that the inner surface of the recess 64A abuts on the outer periphery of one end 122 of the sintered bearing 105 over the entire circumference. In addition, the end face of the other end 123 abuts on the end face of the protruding part 65A protruding from the inner surface of the movable mold 63A. The cavity 61A has a bearing holding space 66 formed to surround the outer periphery of the sintered bearing 105, and a communication part 67 communicates with this bearing holding space 66. In the bearing holding space 66 of the cavity 61, the outer circumferential surface and end surface of the large diameter portion 135 of the sintered bearing 10 and the base end (root portion) of one end 122 near the large diameter portion 135 are exposed. A sprue 68, through which molten resin is supplied, is connected to the cavity 61 via a gate 69, and a plunger (not shown) for injecting molten resin is connected to the sprue 68.

Then, molten resin is injected into the cavity 61A of the clamped injection molding die 60A. At this time, injection pressure acts inside the cavity 61A, but the tip of one end 122 of the sintered bearing 105 is placed in a fitted state in the recess 64 of the fixed die 62A and the movable die 63A, and the other end 123 is abutting the protruding part 65A. Since the tip of one end 122 is not exposed in the cavity 61, the injection pressure acts on the outer surface of the sintered bearing 105 except for the tip of the end 122. Therefore, the molten resin does not leak out to the end face of the end 122 of the sintered bearing 105. Even if the molten resin penetrates between the contact surfaces of the sintered bearing 105 and the die 60, it will only leak slightly on the outer circumferential surface of the end 122 of the sintered bearing 105.

As shown in FIG. 24, this insert bearing 1A has the sintered bearing 105 at one end 122, except for the tip, surrounded by the resin part 20A (the outer circumferential surface and both end faces of the large diameter part 13), and the sintered bearing 105 and the resin part 20A are prevented from rotating by the groove 145 and are integrated in a state where they are prevented from coming off in the axial direction by the large diameter part 135. And because no resin film is formed on both end faces of the sintered bearing as described in the prior art, the appearance is not marred and interference with other parts is suppressed.

[Eighth embodiment]
Fig. 27 shows an enlarged portion of the insert bearing 1B (sintered insert part) of the eighth embodiment, and Fig. 28 shows a sintered bearing 106 used in the insert bearing 1B. As shown in Figs. 27 and 28, the sintered bearing 106 of this embodiment has a large diameter portion 135 similar to the seventh embodiment, and only the shape of the groove formed in this large diameter portion 135 differs from that of the sintered bearing 106 of the seventh embodiment. In the eighth embodiment and the subsequent embodiments, elements common to the seventh embodiment are designated by the same reference numerals to simplify the description.

As shown in Figures 27 and 28, the grooves 146 formed in the large diameter portion 135 of this sintered bearing 106 are ten grooves 146 shorter than half the length (height) of the large diameter portion 135, formed at 36° intervals on the end face side of one end 122 of the large diameter portion 135. The deepest part of each of these grooves 146 is formed as a concave arc surface, and both sides are connected to the outer circumferential surface of the large diameter portion 135 by convex arc surfaces. The shape of the grooves 146 is approximately the same as the groove 14 shown in Figure 2.

[Ninth embodiment]
Fig. 29 shows an insert bearing 1C (insert sintered part) of the ninth embodiment, and Fig. 30 shows a sintered bearing 107 used in the insert bearing 1C. As shown in Figs. 29 and 30, the sintered bearing 107 of this embodiment has a large diameter portion 135 similar to the seventh embodiment, and only the shape of the groove formed in this large diameter portion 135 is different from that of the sintered bearing 106 of the seventh embodiment.

As shown in Figures 29 and 30, the grooves 147 formed in the large diameter portion 135 of this sintered bearing 107 are ten grooves 146 shorter than half the length (height) of the large diameter portion 135, formed at 36° intervals on the end face side of the other end 123 of the large diameter portion 135. The deepest part of each of these grooves 147 is formed as a concave arc surface, and both sides are connected to the outer circumferential surface of the large diameter portion 135 by convex arc surfaces. The shape of the grooves 147 is approximately the same as the groove 14 shown in Figure 10.

[Tenth embodiment]
Fig. 31 shows an insert bearing 1D (insert sintered part) of the tenth embodiment, and Fig. 32 shows a sintered bearing 108 used in the insert bearing 1D. As shown in Figs. 31 and 32, the sintered bearing 108 of this embodiment has a large diameter portion 135 similar to the seventh embodiment, and only the shape of the groove formed in this large diameter portion 135 is different from that of the sintered bearing 106 of the seventh embodiment.

The grooves 148 formed in the large diameter portion 135 of this sintered bearing 108 are formed on the end face on one end 122 side of the large diameter portion 135, as shown in Figures 31 and 32. Four of these grooves 148 are formed at 90° intervals and extend in the radial direction of the end face of the large diameter portion 135. The deepest parts of these grooves 148 are formed flat, and have an inclined surface that gradually increases in diameter from the deepest part to the upper side.

[Eleventh embodiment]
Fig. 33 shows an insert bearing 1E (insert sintered part) of the eleventh embodiment, and Fig. 34 shows a sintered bearing 109 used in the insert bearing 1E. As shown in Figs. 33 and 34, the sintered bearing 109 of this embodiment has a large diameter portion 135 similar to the tenth embodiment, and differs from the sintered bearing 108 of the tenth embodiment only in the position of the groove formed in this large diameter portion 135.

The grooves 149 formed in the large diameter portion 135 of the sintered bearing 109 are formed on the end face of the large diameter portion 135 opposite the one end 122, as shown in Figures 33 and 34. Four grooves 149 are formed at 90° intervals and extend in the radial direction of the end face of the large diameter portion 135. The end face of the large diameter portion 135 coincides with the end face of the other end 122, but the grooves 149 do not erode the end face of the other end 122. In other words, the grooves 149 extend in the radial direction within the range of the large diameter portion 135. The shape of the grooves 148 is the same as the grooves 148.

In the tenth and eleventh embodiments, the grooves 148, 149 are formed on the end face of the large diameter portion 135, but even in this case, the resin part 20A is embedded around the grooves 148, 149, so the same effects as in the above embodiments can be achieved. In other words, the grooves formed in the large diameter portion 135 may be formed on the outer circumferential surface of the large diameter portion 135, may be formed on the end face, or may be formed on both the outer circumferential surface and the end face of the large diameter portion 135.

Furthermore, the present invention is not limited to the configuration of the above-described embodiment, and various changes can be made to the details of the configuration without departing from the spirit of the present invention.
For example, in each of the above embodiments, a groove is formed in the large diameter portion, but a protrusion may be formed along the axial direction instead of the groove. Also, it is preferable to form a plurality of these grooves or protrusions at intervals in the circumferential direction, but it is also possible to form only one.
Furthermore, in the above embodiment, the exterior part is made of a resin part and is insert molded by injection molding, but the present invention can also be applied to an exterior part made of a metal part such as an aluminum alloy and insert molded by casting. In this case, the sintered bearing and the exterior part made of a metal part are integrated by placing the sintered part in a mold (insert molding die) and assembling it (assembling process), and filling the cavity around it with molten metal (molten material) that will become the metal part (filling process).

In the above embodiment, a sintered bearing is used as an example of a sintered part, and an insert bearing is used as an example of an insert sintered part, but this is not limited to this. For example, the sintered part may be a valve seat, a bush, etc. In other words, the present invention is not limited to sintered bearings, but can be applied to any sintered part, and can be applied to all products in which this sintered part is integrated with an exterior part.

1, 1A, 1B, 1C, 1D, 1E Insert bearings (sintered insert parts)
10, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109 Sintered bearings (sintered parts)
10' Molded body 11 Bearing hole 12, 121 End 122 End (one end)
123 End (other end)
13, 131, 135 Large diameter portion 14, 141, 142, 143, 144, 145, 146, 147, 148, 149 Groove 15, 88 Convex strip 20 Resin part (exterior part)
21 Bearing holder 40 Molding die 50, 70, 80 Correction die 60, 60A, 600 Injection molding die (insert molding die)
61, 61A Cavity 62, 62A Fixed mold 63, 63A Movable mold 64, 64A, 65, 641, 651 Recess 65A Protrusion 66 Bearing retaining space

Claims (10)

The method includes a sintered bearing forming step of forming a sintered bearing by powder molding, and an insert molding step of forming an insert bearing by integrating an exterior part with the outer periphery of the sintered bearing,
In the sintered bearing forming step, a large diameter portion having an outer diameter larger than both end portions is formed on an outer periphery of the sintered bearing, and a groove or a protrusion is formed along an axial direction on an outer periphery of the large diameter portion,
The insert molding process includes a mold assembly process in which the outer peripheral surfaces of the tip ends of both ends of the sintered bearing are abutted circumferentially against the inner peripheral surface of an insert molding mold, and the base ends of both ends and the periphery of the large diameter portion are covered with the insert molding mold at intervals to form a cavity on the outer periphery of the sintered bearing, and a filling process in which, after the mold assembly process, the cavity is filled with molten material that will become the exterior part. An insert bearing comprising a sintered bearing and an exterior part integrally molded on the outer periphery of the sintered bearing, a large diameter part having an outer diameter larger than both ends is formed on the outer periphery of the sintered bearing, and a groove or protrusion is formed on the outer periphery of the large diameter part along the axial direction, and the exterior part is formed in a shape that embeds the base end and the large diameter part excluding the tip end at both ends of the sintered bearing. The insert bearing according to claim 2, characterized in that the groove or ridge is formed over the entire length of the large diameter portion. The insert bearing according to claim 2, characterized in that the groove or protrusion is formed from one end face of the large diameter portion to partway along the length. An insert bearing according to any one of claims 2 to 4, characterized in that a tapered portion is formed at both ends, the outer diameter of which gradually increases toward the large diameter portion. The method includes a sintered part forming step of forming a sintered part by powder molding, and an insert molding step of forming an insert sintered part by integrating an exterior part with an outer periphery of the sintered part,
In the sintered part forming step, a groove or a protrusion is formed on an outer periphery of the sintered part except for at least one end portion, which is formed in a tapered shape with an outer diameter gradually decreasing toward a tip end of the sintered part,
The insert molding process includes a mold assembly process in which the outer peripheral surface of the one end portion is brought into circumferential contact with an inner peripheral surface of a tapered recess of an insert molding die, and the groove or protrusion in the region excluding the one end portion is covered with the insert molding die at intervals to form a cavity on the outer peripheral portion of the sintered part, and a filling process in which, after the mold assembly process, a molten material that will become the exterior part is filled into the cavity,
A method for manufacturing an insert sintered part, characterized in that in the mold assembly step, a tapered surface of the end of the sintered part is fitted into a tapered surface of the recess of the insert molding die. A sintered part and an exterior part integrally formed on an outer periphery of the sintered part,
a large diameter portion having an outer diameter larger than both end portions is formed on the outer circumferential portion of the sintered bearing, and at least one of the groove or the protrusion is formed on the outer circumferential surface of the large diameter portion along the axial direction, and the groove or the protrusion is formed along the radial direction of the large diameter portion,
The exterior part is formed in a shape in which the base end portions excluding the tip portions of both ends and the large diameter portion are embedded. The sintered insert part according to claim 7 , wherein the groove or ridge is formed along the axial direction over the entire length of the outer circumferential surface of the large diameter portion. The sintered insert part according to claim 7 , wherein the groove or ridge is formed along the axial direction from one end face of the large diameter portion to a midway point in the length direction. 8. The sintered insert part according to claim 7 , wherein at least one of the ends is formed with a tapered portion whose outer diameter gradually increases toward the large diameter portion.

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