JP3205955B2 - Embedded structure of shaft hole insert fittings for resin molded products - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for burying insert fittings in a shaft hole of a resin molded product such as a pulley made of synthetic resin.

[0002]

2. Description of the Related Art A pulley made of a synthetic resin material (hereinafter referred to as a resin pulley) is used as a pulley or an idler for driving an accessory of an automobile engine. As shown in FIG.
An insert fitting 2 is embedded in an inner diameter boss portion 1a of this type of resin pulley 1 for the purpose of reinforcing in the axial direction and the torsional direction. This insert metal fitting 2 is cylindrical,
A plurality of windows 2a are opened at predetermined intervals in the circumferential direction,
A part of the synthetic resin material forming the resin pulley 1 goes around the inner peripheral side of the insert fitting 2 through the window 2a,
The shaft guide portion 1b is provided. The inner peripheral surface of the shaft guide portion 1b is circumferentially engaged with the rotating shaft 3 and
A spline groove 1c or a key groove is formed to prevent relative rotation of the spline groove and transmit torque.

[0003]

In the above-mentioned conventional structure, the insert fitting 2 receives an axial compressive force due to the tightening of the nut 4 for attaching the resin pulley 1 to the rotating shaft 3. The inner diameter boss portion 1a and the shaft guide portion 1b are sufficiently reinforced in the axial direction, but are spline grooves 1c that receive torque.
Alternatively, since the keyway is formed in the shaft guide portion 1b made of a synthetic resin material, a problem is pointed out that the shear fracture strength of the shaft guide portion 1b in the torsional direction is low. Further, the cylindrical insert fitting 2 is manufactured by a process of cutting a steel pipe or the like and perforating a plurality of windows 2a, but such a process has had to increase the cost.

The present invention has been made under the above circumstances, and its main technical problems are to improve the mechanical strength in the shaft hole of a resin molded product and to reduce the manufacturing cost. Is to reduce.

[0005]

Means for Solving the Problems The technical problems described above are:
This can be effectively solved by the present invention. That is, the embedded structure of the shaft hole insert fitting of the resin molded product according to the present invention includes a cylindrical portion provided with a required number of resin connecting portions and a flange extending from one axial end to the inner diameter side in the resin molded product. And a shaft guide portion made of a synthetic resin material on the inner peripheral side of the cylindrical portion is formed continuously with the synthetic resin material on the outer peripheral side of the cylindrical portion through the resin connecting portion. is there. In addition, the resin contact section
A portion through which a plasticized synthetic resin material passes during molding of a resin molded product, and is formed of, for example, a hole or a notch.

The insert fitting has an L-shaped cross-sectional shape including a cylindrical portion and a flange portion bent from one axial end of the cylindrical portion to the inner diameter side, and is manufactured by punching and stamping a metal plate. Can be.
The shaft guide portion through which the shaft is inserted is formed continuously with the outer peripheral side of the cylindrical portion via a resin connecting portion formed in the cylindrical portion, and is reinforced in the axial direction and the torsion direction by insert metal fittings. . In particular, when the resin molded product is attached to the outer periphery of the shaft by a nut or a bolt screwed to the shaft end, an axial compressive force due to the tightening of the nut or the like is received by the cylindrical portion and the flange portion of the insert fitting. . Therefore, preferably, the flange portion is formed in a tapered shape that forms an obtuse angle with respect to the cylindrical portion, and an appropriate gap is formed between the flange portion and the end surface of the shaft guide portion made of a synthetic resin material. Is not transmitted to the shaft guide portion made of a synthetic resin material on the inner periphery of the cylindrical portion, so that the compressive strain of the shaft hole portion and the destruction due to it are effectively prevented.

In the case where the resin molded product is a rotary component such as a pulley attached to a rotary shaft, a detent means for circumferentially engaging the shaft side is formed at the inner peripheral end of the flange portion of the insert fitting. Thus, the insert fitting has a torque transmitting function. In this case, since the torque transmission to the synthetic resin material is performed at the resin connecting portion of the cylindrical portion which is on the outer diameter side by the radial width of the flange portion with respect to the outer peripheral surface of the rotating shaft, the shear fracture strength in the torsional direction is improved. be able to. Also, in this case, a fuse function of breaking at a predetermined torque is provided to the joint portion made of a synthetic resin material in the resin communication portion, and when abnormal torque is generated, the joint portion is broken to cut off torque transmission, so that the entire device is cut off. It is possible to prevent the abnormality from spreading.

[0008]

FIG. 1 shows an embodiment in which a buried structure of a shaft hole insert fitting of a resin molded product according to the present invention is applied to a resin pulley. Reference numeral 10 denotes a resin molded product. The resin pulley 20 is an insert fitting buried in the inner diameter boss portion 11 of the resin pulley 10. The insert fitting 20 is formed by punching and stamping a metal plate, and has a substantially L-shaped bent cross section cut along a plane passing through the axis, and is disposed in a mold before forming the resin pulley 10. By doing so, the resin pulley 10 is embedded and integrated.

As shown in the perspective view of FIG. 2, the insert fitting 20 includes a cylindrical portion 21 and a flange portion 22 which is bent from one axial end of the cylindrical portion 21 to the inner diameter side and extends. In the cylindrical portion 21, a plurality of circular punching windows 21a are formed at predetermined intervals in the circumferential direction as resin connecting portions, and a part of the synthetic resin material forming the inner diameter boss portion 11 of the resin pulley 10 is When the resin pulley 10 is molded in the mold, the resin pulley 10 goes around the inner peripheral side of the cylindrical portion 21 through the punching window 21a, thereby forming the shaft guide portion 12 continuous with the inner diameter boss portion 11. A spline groove 12a circumferentially engaging with a spline groove 30a formed on the outer peripheral surface of the rotary shaft 30 is formed on the inner peripheral surface of the shaft guide portion 12 made of a synthetic resin material on the inner periphery of the cylindrical portion 21 of the insert fitting 20. A spline groove 22 a is formed in the inner peripheral end of the flange portion 22 of the insert fitting 20 in a direction axially continuous with the spline groove 12 a of the shaft guide portion 12.

The resin pulley 10 having the above structure is inserted into the shaft end of the rotary shaft 30 in its shaft hole, and is fixedly fastened via a spring washer 32 by a nut 31 screwed with the shaft end. Since the axial compression force due to this tightening is received by the insert fitting 20, the axial compression strain on the inner diameter boss portion 11 and the shaft guide portion 12 made of a synthetic resin material is significantly reduced. Conversely, the flange portion 22 of the insert fitting 20 that receives the axial tightening load by the nut 31 is backed up by the shaft guide portion 12 inside the insert metal member 20, so that the buckling of the flange portion 22 itself is effectively reduced. Is prevented.

In the above mounting state, the spline groove 22 a formed on the inner diameter end of the flange portion 22 of the insert fitting 20 is formed along with the spline groove 12 a formed on the inner peripheral surface of the shaft guide 12. It is radially engaged with the spline groove 30a on the surface. Therefore, the torque transmission between the resin pulley 10 and the rotating shaft 30 is substantially performed by the spline groove 22a of the flange portion 22 of the insert fitting 20 and the connecting portion 13 made of a synthetic resin material in the punching window 21a of the cylindrical portion 21. And the torsional shear force exerted by the torque on the shaft guide portion 12 made of a synthetic resin material on the inner peripheral side of the cylindrical portion 21 is significantly reduced.

As a resin connecting portion for forming the plasticized synthetic resin material on the inner peripheral side of the insert fitting 20 at the time of molding the resin pulley 10, a circular punching window 21a as shown in FIG. In addition to these, for example, various embodiments shown in FIGS. 3 to 5 as other embodiments can be considered. Of these, the insert fitting 20 shown in FIG. 3 is formed by punching a plurality of U-shaped notches 21b at predetermined circumferential intervals at an end portion (hereinafter, referred to as a rear end portion) of the cylindrical portion 21 opposite to the flange portion 22. Things. FIG. 4 shows the cylindrical portion 21.
A plurality of bent pieces 21c whose rear ends are bent to the outer diameter side are formed at a plurality of predetermined intervals in the circumferential direction to form a U-shaped notch 21d corresponding to the bent pieces 21c. Due to the torque transmission function of the piece 21c, the torsional strength of the resin pulley 10 is further improved. The insert fitting 20 shown in FIG. 5 is formed by punching out each notch 21e into an undercut shape in which both ends in the circumferential direction are symmetrical oblique sides.
The sliding resistance in the axial direction with respect to the synthetic resin material formed in e is increased, and the joining strength in the axial direction is increased.

In each of the above-described embodiments, the flange portion 22 of the insert fitting 20 has a surface substantially perpendicular to the axis, and the inner surface of the flange portion 22 is located on the inner peripheral side of the cylindrical portion 21. And is integrally joined to the end surface of the shaft guide portion 12 made of a synthetic resin material. Therefore, as described above, the flange portion 22 is backed up by the shaft guide portion 12. In other words, the axial compressive load of the nut 31 is reduced to a certain extent via the flange portion 22. No. 12 is transmitted. Therefore, in the embodiment shown in FIGS. 6 and 7, the flange portion 22 of the insert fitting 20 is tapered at an obtuse angle with respect to the cylindrical portion 21 in order to reliably block the compressive load on the shaft guide portion 12 made of a synthetic resin material. A gap g is formed between the shaft center of the shaft guide portion 12 and an end surface 12b that is substantially perpendicular to the shaft guide portion 12.
Creep can be prevented.

The embedded structure as shown in FIG. 6 is realized by the molding method shown in FIG. That is, first, the insert metal fitting 20 is inserted into the cavity 40a for molding the resin pulley of the metal mold 40 having the upper mold 41, the lower mold 42, and the core mold 43 so that the flange portion 22 thereof is substantially perpendicular to the axis by pressure contact with the upper mold 41. After being elastically deformed, the cavity 40a is filled with a plasticized synthetic resin material. Then, after the synthetic resin material is cured, when the mold 40 is released,
Since the flange portion 22 is restored to the original tapered shape shown by the broken line in the drawing, the flange portion is peeled off from the synthetic resin material formed inside the insert fitting 20, and the gap g shown in FIG. 6 is formed.

According to this embodiment, FIG.
In order to show the state of attachment to the nut 31, the tightening load of the nut 31 is applied by the insert fitting 20 to the rear end face 2 of the cylindrical portion 21.
The flange portion 22 is elastically deformed substantially at right angles to the shaft center when received at 1f and the inner diameter end portion 22b of the flange portion 22, thereby generating a large pressing force against the seat surface 31a of the nut 31. For this reason, the axial compressive force due to the tightening of the nut 31 is hardly transmitted to the shaft guide portion 12 made of a synthetic resin material on the inner periphery of the cylindrical portion 21, and the flange portion 22 has the tapered shape as described above. Since it has a function of a washer that generates a large pressing force against the bearing surface 31a of the nut 31 by being elastically deformed from the original shape, the spring washer 32 as shown in FIG. 1 is not required.

In each of the illustrated embodiments, when forming the resin pulley 10, a cylindrical portion is used as a resin connecting portion for turning a part of the plasticized synthetic resin material into the inner peripheral side of the insert fitting 20. The punching window 21a or the cutouts 21b, 21d, 21e formed in the opening 21 are relatively large, and their sizes are adjusted to an allowable torque value,
By appropriately setting the material and the like of the synthetic resin material, the punching window 21a or the notches 21b, 21d,
A fuse function for preventing an excessive load can be given to the joint portion 13 made of a synthetic resin material in 21e. That is,
For example, when an abnormal torque is generated in a rotating device such as a pump driven by the resin pulley 10,
Due to this torque, the connecting portion 13 as a fuse is broken by a circumferential shearing force, and the torque transmission is interrupted. Therefore, it is possible to prevent the abnormalities due to the excessive torque from spreading to the entire device on the driving side.

The present invention is not to be construed as being limited to the embodiment shown in the drawings, and can be applied to a buried structure of an insert fitting buried in a shaft hole of a resin molded product other than the resin pulley 10. is there. As the rotation preventing means formed on the inner peripheral surface of the shaft guide portion 12 made of a synthetic resin material and the inner diameter end portion of the flange portion 22 of the insert fitting 20, a key groove or the like can be formed in addition to the spline groove 22a. However, depending on the resin molded product, such a detent means is not always necessary.

[0018]

According to the embedded structure of the shaft hole insert fitting of the resin molded product according to the present invention, the following effects are realized. (1) The insert fitting has an L-shaped cross-section and can be manufactured by stamping and stamping a metal plate, so that the manufacturing cost is reduced by 30 to 60% as compared with a conventional steel pipe. . (2) Since the shaft hole of the resin molded product is reinforced in the axial direction and the torsion direction by the cylindrical portion and the flange portion of the insert fitting, the durability is improved. (3) By forming a rotation preventing means at the inner peripheral end of the flange portion of the insert fitting with respect to the shaft, it is possible to improve the shear fracture strength of the shaft hole portion in the torsional direction. (4) By forming the flange portion of the insert fitting into a tapered shape to provide spring properties, it is possible to prevent the shaft hole made of synthetic resin material on the inner periphery of the cylindrical portion from being broken due to compressive strain. Becomes unnecessary. (5) The breakage of the synthetic resin material in the resin connecting portion formed in the cylindrical portion can prevent the device from being damaged due to the generation of abnormal torque.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an embodiment in which an embedded structure of a shaft hole insert fitting of a resin molded product according to the present invention is applied to a resin pulley, cut along a plane passing through an axis.

FIG. 2 is a perspective view showing the insert alone in the embodiment of FIG. 1;

FIG. 3 is a perspective view showing an insert fitting alone according to another embodiment of the present invention.

FIG. 4 is a perspective view showing an insert fitting alone according to another embodiment of the present invention.

FIG. 5 is a perspective view showing an insert fitting alone according to another embodiment of the present invention.

FIG. 6 is a cross-sectional view of a principal part showing another embodiment of the present invention by cutting along a plane passing through an axis.

FIG. 7 is a perspective view showing the insert fitting alone in the embodiment of FIG. 6;

FIG. 8 is an explanatory view showing a molding method for realizing the embodiment of FIG. 6;

FIG. 9 is a cross-sectional view of a main part showing a mounting state of the resin pulley in the embodiment of FIG. 6 cut along a plane passing through an axis.

FIG. 10 is a cross-sectional view showing a conventional example of a buried structure of a shaft hole insert fitting of a resin molded product, cut along a plane passing through an axis.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Resin pulley (resin molded article) 11 Inner diameter boss part 12 Shaft guide part 12a Spline groove 12b End face 13 Coupling part 20 Insert fitting 21 Cylindrical part 21a Punching window (resin connection part) 21b, 21d, 21e Notch (resin connection part) 21c Bending piece 21f Rear end face 22 Flange part 22a Spline groove (rotation preventing means) 22b Inner diameter end part 30 Rotating shaft 31 Nut 32 Spring washer 40 Mold 40a Cavity 41 Upper mold 42 Lower mold 43 Core mold

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) B29C 45/00-45/24 B29C 45/46-45/84

Claims (4)

(57) [Claims] 1. A required number of resin connecting portions (21a, 21b, 21d, 21) are provided on a resin molded product (10).
e) Opened cylindrical part (21) and this cylindrical part (2)
An insert fitting (20) comprising a flange portion (22) extending from one end in the axial direction to the inner diameter side of 1) is embedded, and a shaft guide portion made of a synthetic resin material on the inner peripheral side of the cylindrical portion (21). (12) is the resin connecting portion (21a, 21b, 2)
A buried structure of a shaft hole insert fitting of a resin molded product, which is formed continuously with a synthetic resin material on the outer peripheral side of the cylindrical portion (21) through 1d, 21e). 2. The shaft guide according to claim 1, wherein the flange portion (22) is formed in a tapered shape forming an obtuse angle with respect to the cylindrical portion (21), and the flange portion (22) and the shaft guide made of a synthetic resin material. End face (12b) of part (12)
And a gap (g) is formed between the metal member and the shaft hole insert fitting of the resin molded product. 3. The method according to claim 1, wherein a detent means (22a) is formed at an inner peripheral end of the flange portion (22) so as to engage with the shaft side in a circumferential direction. Embedded structure of shaft hole insert fittings for resin molded products. 4. The resin connecting part (21a, 21a) formed in the cylindrical part (21) according to claim 1,
(b, 21d, 21e). A buried structure of a shaft hole insert fitting for a resin molded product, wherein a joint portion (13) made of a synthetic resin material in (b), (21d, 21e) is a fuse portion that breaks at a predetermined torque.