JP5887803B2 - Fastening structure of resin molding - Google Patents

Description

  The present invention relates to a fastening structure of a resin molded body made of a thermoplastic resin, and more particularly to a technique for fastening a member to be fastened to a hollow molded body made of a synthetic resin with a screw member.

  Conventionally, it is desired to fasten another member with a screw member to a synthetic resin hollow molded body. The hollow molded body is formed with a particularly thin wall. For this reason, even if the male screw member is simply screwed into the wall portion of the hollow molded body, the fitting length of the screw cannot be sufficiently secured, and the necessary fastening force cannot be obtained. Accordingly, the hollow molded body is required to have a fastening structure that can sufficiently secure the fitting length of the screw. Various techniques have been proposed as a fastening structure for hollow molded bodies (see, for example, Patent Document 1).

  As shown in FIG. 7, in the fastening structure 100 described in Patent Document 1, in blow molding of the hollow panel 101 made of synthetic resin, a concave nut embedded hole 103 is provided in a part of the wall portion 102, and after molding, The nut 104 is fitted into the nut embedding hole 103. According to this technique, by fitting the nut 104 to the wall portion 102, the fitting length of the screw can be increased even with the thin wall portion 102.

  Further, in Patent Document 2, in a method of manufacturing a resin molded product, a nut is cast into a hard resin to form a hard resin molded product, and this hard resin molded product is further cast into the resin molded product. This technique is disclosed. According to this technique, the strength around the nut can be increased by the hard resin molding.

Japanese Patent No. 2791826 JP 2009-121635 A

  In the fastening structure of Patent Document 1 described above, the holding portion 105 that holds the nut 104 has substantially the same thickness as the wall portion 102 of the hollow molded body 101, and the wall thickness is small. Even with such a thin holding section 105, there is no problem in strength if the force applied to the holding section 105 is small. However, in recent years, a fastening structure with higher rigidity has been demanded, and a technique for further increasing the strength around the screw member is desired.

  In this regard, in the technique disclosed in Patent Document 2, the nut is wrapped with a hard resin molded body. According to this technique, the amount of resin around the screw member can be increased, and the strength around the screw member can be increased.

  However, the wall portion of the hollow molded body is generally molded by pressing a cylindrical parison or sheet against the molding surface of the mold. It is difficult to cast a hard resin molding into the wall portion thus molded. That is, the technique of Patent Document 2 is suitable for an injection molded product obtained by flowing a molten resin in a mold, but is not suitable for a hollow molded body. For this reason, in a hollow molded object, the technique which can increase the resin amount of a screw member periphery is calculated | required.

  This invention is made | formed in view of such a situation, The objective is to increase the amount of resin, and to provide the fastening structure of the resin molded object which can implement | achieve the strength improvement of a screw member periphery, especially a hollow molded object. It is in.

Fastening structure of the resin molded body according to the present invention, the workpieces on the wall surface of the thermoplastic resin of the resin molded body in the fastening structure of the resin molded body fastened with the male screw member, integral with the wall portion of the front Symbol resin molding a thermoplastic resin parts products to be of, has a cylindrical body which exhibits the wall portion be made of synthetic resin to be partially recessed toward the outside to the inside substantially barrel bottomed tubular, The cylindrical body has an outer peripheral surface wrapped in a recessed portion of the wall portion, and an inner peripheral surface that opens into the wall surface and into which the male screw member is screwed, and the outer peripheral surface includes an opening of the cylindrical body. A taper surface is provided to reduce the diameter toward the end and prevent the tubular body from being pulled out from the depressed portion.

The fastening structure of the resin molded body according to the present invention is further characterized in that the thickness of the peripheral wall of the cylindrical body is set larger than the thickness of the wall portion of the resin molded body .
In the fastening structure of the resin molded body according to the invention , the outer peripheral surface further extends in a band shape along the axis of the cylinder, and a convex portion that prevents rotation around the axis of the cylinder relative to the depression. A recess is provided.

  According to the present invention, the amount of resin around the male screw member can be greatly increased by the cylindrical body made of synthetic resin. Therefore, the fastening strength around the male screw member can be increased.

It is sectional drawing of the fastening structure of the hollow molded object concerning this invention. (A) is a perspective view of a cylinder, (b) is a cross-sectional view of a cylinder, and (c) is a figure showing the example of change of (b). It is a figure which shows the shaping | molding method of a hollow molded object, (a) is a figure which shows the process of inserting a cylinder, (b) is a figure which shows the process of pushing out a parison, (b) is a figure which shows a blow process. It is an exploded view of the fastening structure of a hollow molded object. It is a figure explaining the effect | action of the taper surface of a cylinder. It is AA sectional view taken on the line of FIG. 5, and is a figure explaining the effect | action of a convex part. It is a figure explaining the basic composition of the conventional fastening structure.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention (hereinafter referred to as embodiments) will be described in detail with reference to the accompanying drawings. Note that the same number is assigned to the same element throughout the description of the embodiment.

  As shown in FIG. 1, a fastening structure 10 for a hollow molded body is configured to fasten a member 12 to be fastened to a wall surface 21 of a hollow molded body 20 with a male screw member 11, and is integrated into the hollow molded body 20 by insert molding. A cylindrical body 30 is provided.

The configuration of each part of the fastening structure 10 will be described in detail.
The hollow molded body 20 is, for example, a panel constituting an exterior body of an electric device such as a computer or a copying machine, or a panel constituting a housing body such as a cabinet or a locker. The material of the hollow molded body 20 can be selected from various synthetic resin materials, but polyolefin resins such as polyethylene and polypropylene are suitable. In addition, it is also possible to obtain the hollow molded body 20 having high rigidity and high heat insulation by filling the hollow portion 22 with a foam material.

  The hollow molded body 20 has two wall portions 23 and 24 that face each other with a hollow portion 22 therebetween. One wall portion 23 is formed with a depressed portion 25 that is recessed inward from the wall surface 21 side (outside). The depressed portion 25 is a portion formed by the cylindrical body 30 when the hollow molded body 20 is molded, and wraps around the outer peripheral surface 31 of the cylindrical body 30.

  The fastened member 12 is, for example, a metal plate material such as a hinge. The male screw member 11 is, for example, a metal screw or bolt. The member to be fastened is not limited to a metal plate, and any type, shape, and material can be used as long as the member can be attached to the wall surface 21. The male screw member may have any shape and material as long as it has a male screw. In particular, the male screw member is fixed while the male screw cuts the cylindrical inner peripheral surface 32. Arbitrary things such as length and pitch can be used, and it is not necessary to select one that matches the thread of the nut as in the case of inserting the nut.

  As shown in FIG. 2A, the cylindrical body 30 is an insert part made of a synthetic resin that is inserted into a mold in advance prior to molding the hollow molded body 20 (see FIG. 1). The cylindrical body 30 has a substantially barrel-shaped bottomed cylindrical shape and has a cylindrical inner peripheral surface 32 that opens to the wall surface 21 (see FIG. 1). The male screw member 11 (see FIG. 1) is screwed into the inner peripheral surface 32. The inner diameter of the inner peripheral surface 32 is set to be smaller than the outer diameter of the screw of the male screw member 11 such that the male screw member 11 is screwed. The thickness of the peripheral wall of the cylindrical body 30 is preferably set larger than the thickness of the wall portion 23 (see FIG. 1).

  The material of the cylindrical body 30 can be selected from various materials including polyolefin resins such as polyethylene and polypropylene, but in consideration of welding with the hollow molded body 20, it is molded with the same material as the hollow molded body 20. It is preferable. For example, the cylindrical body 30 may be molded using an extra material (so-called burrs) protruding from the cavity of the mold when the hollow molded body 20 is molded. In this case, good welding with the hollow molded body 20 can be obtained, and material loss can be reduced.

  A tapered surface 35 that is reduced in diameter toward the opening end 33 is provided on the opening end 33 side of the outer peripheral surface 31. Further, the outer peripheral surface 31 is provided with a convex portion 36 extending in a band shape from the open end 33 toward the bottom portion 34 along the axis 30 a of the cylindrical body 30.

  As shown in FIG. 2B, the convex portion 36 is formed in a semi-cylindrical cross section, and for example, a plurality (four in this case) are provided in the circumferential direction of the outer peripheral surface 31. In addition, as shown in FIG. 2C, a concave portion 37 having a semicircular cross section may be provided on the outer peripheral surface 31 instead of the convex portion 36. In addition, the number and shape of the convex part 36 and the recessed part 37 are not specifically limited to embodiment, and are arbitrary.

Next, a method for forming the hollow molded body 20 will be described with reference to FIG.
As shown in FIG. 3, in this molding method, the first mold 41 for molding one wall portion 23 (see FIG. 1) of the hollow molded body and the other wall portion 24 (see FIG. 1) are molded. A second mold 42 is used. The molding surface 41 a of the first mold 41 is provided with a protrusion 43 that protrudes toward the second mold 42.

  As shown in FIG. 3A, first, the cylindrical body 30 is inserted into the protrusion 43. Next, as shown in FIG. 3B, after the molten cylindrical parison 44 is extruded between the molds 41 and 42, the molds 41 and 42 are closed, and the parison 44 is molded into the mold. 41, 42. And as shown in FIG.3 (c), gas is blown into the parison 44, and the parison 44 swells so that it may closely_contact | adhere to the molding surfaces 41a and 42a and the outer peripheral surface 31 of the cylinder 30. FIG. At this time, the parison 44 is sufficiently spread in the narrow space 45 formed between the tapered surface 35 and the molding surface 41a (arrow (1)).

  As a result, the depressed portion 25 is formed so as to wrap the entire outer peripheral surface 31. At the same time, a tapered holding portion 26 that holds and holds the tapered surface 35 is formed in the depressed portion 25. After cooling, the molds 41 and 42 are opened, the hollow molded body 20 is taken out, and the burrs protruding from the cavity 46 are removed.

  Then, as shown in FIG. 4, the hollow molded body 20 in which the cylindrical body 30 is integrated is obtained. Then, the male screw member 11 is passed through the through hole 12 a of the fastened member 12 and screwed into the inner peripheral surface 32 of the cylindrical body 30. As a result, the fastened member 12 is fastened between the head portion 11 a of the male screw member 11 and the wall surface 21.

  As described above, according to the embodiment of the present invention described above, the amount of resin around the male screw member 11 can be greatly increased by the cylindrical body 30 made of synthetic resin, and the strength around the male screw member 11 can be increased.

  Further, as shown in FIG. 5, due to the tightening of the male screw member 11, the movement of the fastened member 12, etc., the force F is received in the direction in which the cylindrical body 30 is pulled out (the direction indicated by the arrow in the drawing). In addition, the holding portion 26 firmly presses the tapered surface 35. As a result, the cylindrical body 30 is prevented from being pulled out. In addition, it is also possible to prevent pull-out by forming a step portion, a groove portion, or a flange portion along the circumferential direction instead of the tapered surface 35.

  Furthermore, as shown in FIG. 6, when the male screw member 11 is screwed in, the cylindrical body 30 receives the torque T in the direction indicated by the arrow in the figure, but the convex portion 36 is engaged with the concave portion of the wall portion 23. Therefore, rotation around the axis 30a is prevented. Thereby, the male screw member 11 can be fastened with higher torque, and the fastening force can be increased. In addition, even if the recessed part 37 (refer FIG.2 (c)) is used instead of the convex part 36, the effect | action similar to the convex part 36 is acquired. Further, instead of the convex portion 36 and the concave portion 37, it is possible to prevent rotation by making the cross section of the cylindrical body 30 into an irregular (non-circular) cross section.

  As mentioned above, although this invention was demonstrated using embodiment, it cannot be overemphasized that the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiments. Further, it is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

  For example, in the embodiment, the hollow molded body is molded by a blow molding method using a cylindrical parison, but the molding method is not particularly limited to the blow molding method and is arbitrary. For example, instead of a cylindrical parison, two molten sheets are arranged between a plurality of divided molds, and a sealed space between the sheets and the divided molds is sucked to form a hollow molded body. You may shape | mold. Such a molding method is suitable for producing a resin molded body having higher rigidity because it is easy to put a foam material or the like as a core material between two sheets. In addition, when forming a resin molding using a mold, such as vacuum / compression molding using a thermoplastic resin sheet or injection molding using a molten resin, insert parts are set in the mold and the resin molding What is necessary is just to integrate with a wall surface.

DESCRIPTION OF SYMBOLS 10 Fastening structure 11 Male screw member 12 Fastened member 20 Hollow molded body 21 Wall surface 23 Wall part 25 Depressed part 30 Cylindrical body 30a Axis 31 Outer peripheral surface 32 Inner peripheral surface 33 Open end 35 Taper surface 36 Convex part 37 Concave part

Claims (3)

In the fastening structure of the resin molded body that fastens the member to be fastened to the wall surface of the resin molded body made of thermoplastic resin with a male screw member,
Before Symbol a thermoplastic resin parts products are integrated in the wall portion of the resin molding, there the wall portion made of synthetic resin to be partially recessed toward the outside to the inside substantially barrel-bottomed It has a cylindrical body that exhibits a cylindrical shape,
The cylindrical body has an outer peripheral surface wrapped in a depressed portion of the wall portion, and an inner peripheral surface that opens in the wall surface and into which the male screw member is screwed.
A fastening structure for a resin molded body, wherein the outer peripheral surface is provided with a tapered surface that reduces a diameter toward an opening end of the cylindrical body and prevents the cylindrical body from being pulled out from the depressed portion.   2. The fastening structure for a resin molded body according to claim 1, wherein a thickness of a peripheral wall of the cylindrical body is set larger than a thickness of a wall portion of the resin molded body.   3. The outer peripheral surface is provided with a convex portion or a concave portion that extends in a strip shape along the axis of the cylindrical body and prevents rotation around the axis of the cylindrical body with respect to the depressed portion. The fastening structure of the resin molding as described in 2.

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