JPH094632A - Bush - Google Patents

Abstract

PURPOSE: To increase the strength of a weld part partially formed on the outer peripheral side of a bush at the time of forming a synthetic resin-made molding. CONSTITUTION: A bush 10 is formed in such a manner that a projecting piece 12 is beaten out approximately in the tangential direction from one part in the circular direction of a cylindrical metallic bush main body 11, a window part 11a formed by being beaten out is formed in a part of the circumferential wall of a bush main body 11 and when it is integrally buried in the hole part 2 of a synthetic resin molding 1 by means of insert forming, the projecting piece 12 is set in a metallic die so that it may be positioned to the opposite side in the circular direction relative to the inflow side of plasticized synthetic resin material. The plasticized synthetic resin material to be formed generates turbulent flow F' on the tip of flow by means of projecting piece 12 and the window part 11a so that a fused weld part may be formed on a surface complicatedly combined or intertwined, thereby its strength against any residual tensile stress generated by volume contraction, etc., of the synthetic resin after formation may be increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bush that is integrally embedded in the inner periphery of a hole or the like for inserting a bolt of a synthetic resin molded product to reinforce the hole.

[0002]

2. Description of the Related Art As shown in FIG. 6, generally, the inner periphery of a bolt insertion hole 2 formed in a flange portion 1a of a synthetic resin molded product 1 is reinforced by a metal bush 3 against bolt tightening force. Has been done and this bush 3
Is integrally embedded in the inner periphery of the hole 2 by insert molding when the synthetic resin molded product 1 is molded. Conventionally, as this type of bush 3, a bush having a simple cylindrical shape as illustrated is used. Also, bush 3
The outer peripheral surface of the is subjected to knurling (not shown) or the like for preventing rotation and coming off.

[0003]

In the molding of the synthetic resin molded product 1, the bush 3 is preset at a predetermined position in a mold (not shown) corresponding to the flange portion 1a.
The plasticized synthetic resin material that has flowed in through the gate G of the mold flows in the outer periphery of the bush 3 while being branched toward both sides in the circumferential direction as indicated by an arrow F in the drawing, and the tip of the flow F is formed. Since the portions collide with each other at a position symmetrical with respect to the gate G in the circumferential direction and merge with each other, a weld portion W is formed substantially along a plane passing through the axial center of the bush 3. In this weld portion W, the flow F of the plasticized synthetic resin material is not completely fused and is discontinuous, so that the other portion (non-weld) formed by the continuous flow F of the plasticized synthetic resin material is used. Part)
In comparison with, the tensile strength causes a strength reduction of about 60%. Therefore, in the case of the weld portion W formed along the plane passing through the axial center of the bush 3, the residual tensile force in the circumferential direction generated around the bush 3 due to shrinkage of the synthetic resin material after molding, heat cycle, or the like. It is pointed out that stress may cause cracking.

The present invention has been made under the circumstances as described above, and its technical problem is that a weld portion formed by a part of the outer circumference of a bush is molded at the time of molding a synthetic resin molded product. It is to improve the strength.

[0005]

The above-mentioned technical problems are as follows.
This can be effectively solved by the present invention. That is, the first of the present invention is, in a bush integrally embedded in the inner periphery of the hole of the synthetic resin molded product at the time of molding the synthetic resin molded product, a bush main body having a cylindrical shape and a circumference of the bush main body. A certain number of projecting pieces projecting toward the outer peripheral side are provided in a part of the direction, and the projecting pieces are formed by punching out a part of the bush main body in a direction intersecting the radial direction. In the second aspect of the present invention, the bush body is formed by roll-bending a metal plate, and the projecting piece has an end portion of an opposite side formed by roll-bending the metal plate with respect to an axis of the bush body. It is folded back into an inclined shape.

[0006]

When a synthetic resin molded product in which a bush is integrally embedded in a hole is molded, a required number of projecting pieces formed on the bush body and projecting to the outer peripheral side flow to both sides in the circumferential direction on the outer periphery of the bush main body. It causes turbulence in the plasticized synthetic resin material. For this reason, a non-planar weld portion is formed in which the flows of the plasticized synthetic resin material from both sides in the circumferential direction are complicatedly mixed and combined in an intertwined or entangled state, and the strength thereof is improved. Further, since the projecting piece projects into the synthetic resin, the fixing property of the bush to the synthetic resin molded product is improved.

When the projecting piece is formed by punching out a part of the peripheral wall of the bush main body in a direction intersecting the radial direction, in addition to the projecting piece, one of the bush main body The window portion formed in the portion also has the function of causing the turbulent flow, and the rotation-preventing and slip-out preventing actions. Further, when the bush body is formed by roll-bending a metal plate, a projecting piece obtained by folding back the ends of mutually opposing sides of the metal plate by roll-bending into a shape inclined with respect to the axis of the bush body. Has a function of causing spiral turbulence at the tip of the flow of the plasticized synthetic resin material on the outer periphery of the bush body to be entangled with each other, whereby the weld portion is formed in a complicated and intricate non-planar shape. It

[0008]

1 is a perspective view showing a first embodiment of a bush according to the present invention. That is, the bush 10 according to this embodiment has a cylindrical metal bush body 11 and a portion of the bush body 11 in the circumferential direction from the circumferential direction to the outer circumferential side in a direction intersecting the radial direction (for example, a substantially tangential direction). It is provided with one protruding piece 12. This protrusion 12
Is formed by punching out a part of the peripheral wall of the metal bush main body 11 in a U shape, and by the punching, a part of the peripheral wall of the metal bush main body 11 has a shape corresponding to the protrusion 12. The window portion 11a is opened.

FIG. 2 is an explanatory view showing a molding process of a synthetic resin molded product 1 in which the bush 10 of the first embodiment is integrally embedded. That is, the bush 10 is integrally embedded in the hole 2 formed in the flange portion 1a of the synthetic resin molded product 1 by insert molding. When the synthetic resin molded product 1 is molded, the bush 10 is plastic. It is preset at a predetermined position in the mold corresponding to the flange portion 1a so that the projecting piece 12 is located on the opposite side in the circumferential direction with respect to the gate G which is the inflow port of the synthetic resin material. For this reason, the plasticized synthetic resin material that has flowed in from the gate G is, as shown by the arrow F in FIG.
1. The gate G is branched to the both sides in the circumferential direction,
When joining together at a position on the opposite side, turbulent flow F'is generated by the projecting piece 12 and the window portion 11a, so that a flow portion from both is complicatedly formed to form a welded portion which is fused in an intertwined or entangled state. It For this reason, the strength of the weld portion against the residual tensile stress in the circumferential direction generated by the volume shrinkage of the synthetic resin after molding is improved.

Considering the state after molding of the synthetic resin molded product 1, the projecting piece 12 projects into the wall thickness of the flange portion 1a made of synthetic resin, and a part of the synthetic resin is present in the bush body. Since it enters into the window portion 11a of 11, the shearing cross-sectional area in the circumferential direction and the axial direction increases.
Therefore, the fixing property of the bush 10 to the synthetic resin molded product 1 is remarkably improved, as compared with the conventional rotation preventing / disengaging device by knurling. Therefore, it is not necessary to knurl the outer peripheral surface of the bush body 11.

FIG. 3 is a perspective view showing a second embodiment of the bush according to the present invention, and FIG. 4 is a development view thereof. That is, the bush 10 ′ according to the second embodiment has a cylindrical metal bush main body 13, a part of which in the circumferential direction projects from both axial ends to the outer peripheral side and is inclined with respect to the axial center of the bush main body 13. And the bush 1 is provided on a part in the circumferential direction of the end face on the one side in the axial direction.
Notch 1 for positioning when setting 0'in the mold
5 are formed.

The bush body 13 is formed by roll-bending a metal plate 130 punched into a shape shown in the development view of FIG. In this metal plate 130, the opposite ends of the opposite sides 131, 131 formed by roll bending serve as triangular bending margins 132, 132, respectively, while the other ends of the opposite sides 131, 131 are bent at the opposite ends. Teens 13
The extension parts 133 and 133 having a shape substantially corresponding to 2 are formed. The bending margin 132 serves as the projecting piece 14 by being folded back along the portion indicated by the broken line in the drawing to the side opposite to the roll bending direction of the metal plate 130, and the extension 133 is also shown in FIG. Since the bending margin 132 is folded back to form the protrusion 14,
This is to prevent a gap having a shape corresponding to the bending margin 132 from being formed in a part of the peripheral wall of the.

FIG. 5 is an explanatory view showing a molding process of a synthetic resin molded product 1 in which the bush 10 'of the second embodiment is integrally embedded. That is, the bush 10 ′ is positioned and set by the notch 15 at a predetermined position in the mold (not shown) so that the projecting pieces 14, 14 are located on the opposite sides in the circumferential direction with respect to the gate G. Therefore, the plasticized synthetic resin material that has flowed in from the gate G in the molding step flows while branching to the outer circumferential side of the bush body 13 in the circumferential direction as shown by the arrow F in the process of shaping the flange portion 1a, Turbulent flow is generated by the projecting pieces 14, 14 at a position opposite to the gate G. That is, since both the projecting pieces 14 and 14 have a shape inclined in the same direction with respect to the axial center of the bush main body 13, a part of the flow F of the plasticized synthetic resin material is guided in the spiral direction, and is separated. A part of the flow of the air flows over or bypasses the projecting piece 14, and these flows intersect, merge, or collide with each other. Therefore, since the weld portion formed by this is entangled and fused in a very complicated manner and is formed into a non-planar shape that is included in a wide range in the circumferential direction, the strength against the residual tensile stress in the circumferential direction after molding is high. Increase.

Further, since the projections 14 and 14 are formed by obliquely folding back the corners (bending margins 132) of the metal plate 130, the projections 14 and 14 are not formed in a shape projecting to both axial sides of the bush body 13. Therefore, it is not exposed from the end surface of the flange portion 1a of the molded synthetic resin molded product 1. In the second embodiment, after the synthetic resin molded product 1 is molded, the projecting pieces 14, 14 project into the wall thickness of the flange portion 1a made of synthetic resin. It will be easily understood that the anti-rotation and anti-loose functions improve the fixing property.

The present invention is not limited to the illustrated embodiment. For example, also in the bush 10 of the first embodiment shown in FIGS. 1 and 2, at the position on the axially one end surface of the bush body 11 on the opposite side to the projecting piece 12 in the circumferential direction, the same as in the second embodiment. Alternatively, a notch for positioning may be formed. Further, the size and inclination angle of the projecting pieces 12 and 14 are arbitrarily determined.

[0016]

According to the bush of the present invention, when molding a synthetic resin molded article in which the bush is integrally embedded,
The protrusion protruding from the bush main body to its outer periphery creates a fused state in which the weld part formed in the confluence part of the plasticized synthetic resin material is intricately entangled during the shaping process, and the shrinkage of the synthetic resin material after molding or The strength against the residual tensile stress in the circumferential direction generated around the bush due to a heat cycle or the like can be improved, the occurrence of cracks can be effectively prevented, and the fixation of the bush to the molded product can be improved.

[Brief description of drawings]

FIG. 1 is a perspective view showing a first embodiment of a bush according to the present invention.

FIG. 2 is an explanatory view showing a flow of a plasticized synthetic resin material in a molding process of a synthetic resin molded product in which the bush of the first embodiment is integrally embedded.

FIG. 3 is a perspective view showing a second embodiment of the bush according to the present invention.

FIG. 4 is a development view of the bush of the second embodiment.

FIG. 5 is an explanatory view showing a flow of a plasticized synthetic resin material in a molding process of a synthetic resin molded product in which the bush of the second embodiment is integrally embedded.

FIG. 6 is an explanatory diagram showing a flow of a plasticized synthetic resin material in a molding process of a synthetic resin molded product in which a bush according to a conventional example is integrally embedded.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Synthetic resin molded product 1a Flange part 2 Hole part 10,10 'Bushing 11,13 Bush main body 11a Window part 12,14 Projection piece 15 Notch 130 Metal plate 131 Opposing side 132 Bending allowance 133 Extension part

Claims (2)

[Claims] 1. A bush body (11) having a cylindrical shape in a bush (10) integrally embedded in a hole (2) of a synthetic resin molded product (1) when the synthetic resin molded product (1) is molded. ) And a required number of projecting pieces (12) projecting to the outer peripheral side in a part of the bush body (11) in the circumferential direction, the projecting piece (12) includes a part of the bush body (11). A bush characterized by being formed by stamping in a direction intersecting the radial direction. 2. A bush body (13) having a cylindrical shape in a bush (10 ') integrated with a hole (2) of a synthetic resin molded product (1) when the synthetic resin molded product (1) is molded. And a required number of projecting pieces (14) projecting to the outer peripheral side in a part of the bush body (13) in the circumferential direction, the bush body (13) being formed by roll-bending a metal plate (130). The projecting piece (14) has a shape inclined with respect to the axis of the bush body (13) by using the end portion of the opposite side (131) formed by roll bending of the metal plate (130) as a bending margin (132). A bush characterized by being folded back in.