JP3040954B2 - Plastic hinge - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a plastic hinge used for furniture, stationery, personal items, and the like.

[0002]

2. Description of the Related Art Conventionally, in a plastic hinge (or hinge), a cylindrical shaft insertion portion is provided so as to alternately mesh with an end face of a pair of blades, and a metal inner diameter is provided on the cylindrical inner diameter. It is customary to insert a pin. Also,
In the case of a plastic pencil case or the like, polypropylene is used for 0.25
It is customary to integrally form a thin plate of about mm and use this as a hinge.

[0003]

There are various types of plastic products having hinges which repeatedly rotate and bend over a long period of use, and the above-mentioned thin plate hinges are usually used. Since such a hinge is made of a plastic molding die in a flat shape, even if it is bent, a force that always attempts to restore it to a flat shape is acting, so it can be applied to certain types of products. There was a drawback that the usability was poor when applied. Moreover, polypropylene, which is a material suitable for plastic hinges, does not always have physical and chemical properties that are satisfactory for all products. Rather, many products require the use of other high-strength, high-rigidity plastics, but such high-strength, high-rigidity materials cannot be used as thin-plate hinges.

Further, similarly to a conventional metal hinge, a pair of wing plates each having a cylindrical shaft insertion portion are formed of plastic, and a metal pin is inserted into the inside of the pair of wing plates. Cutting, assembling, etc., it has been relatively expensive.

[0005]

SUMMARY OF THE INVENTION The present invention seeks to integrally mold a pivotable hinge having a structure similar to that of a conventional metal hinge with plastic, and for that purpose, a structure of a plastic molding die. By sliding a part (core) of the mold in the direction perpendicular to the mold opening direction, a support shaft is protruded from the end surface of the cylindrical portion, and a cylindrical portion fitted to the support shaft is simultaneously formed. It was made. As a result, the pair of hinges is completed by one-shot molding, and no assembling work is required.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the drawings. As shown in FIG. 1, the hinge according to the present invention has several columnar shaft supports 1a and cylindrical shaft inserts 1b, 2b which engage with each other on adjacent end surfaces of a pair of blades 1, 2, and a central portion thereof. The other cylindrical shaft insertion portion 1b is attached to the cylindrical shaft support portion 1a,
The support shafts 1s and 1s penetrating through the center shaft of 2b are integrally formed to protrude. 1d is a hole for a mounting screw.

An embodiment of a mold for forming such a hinge integrally formed with plastic will be described. A movable-side mold plate 10 of the injection molding die includes blade blade cavities 11 and 12 for forming a pair of blades 1 and 2, a columnar shaft support 1 a, and cylindrical shaft inserts 1 b and 2 b. Column-shaped cavity 11a for molding a semicircular portion, cylindrical-shaped cavity 1
1b, 11b, 12b, and 12b are recessed on the adjacent end surfaces of the respective blade cavity portions 11 and 12. Therefore, the cavity partition wall 13 for partitioning between the adjacent columnar portion cavities 11a, 12b, 11b is erected. On the other hand, the fixed side mold plate 20 has
a, The cylindrical cavities 21a, 22b, 21b for molding the semicircular portions on the opposite sides of the shaft insertion portions 1b, 2b are recessed at positions facing the cylindrical cavities provided in the movable mold plate 10. I do. Also in this fixed-side mold plate 20, the cavity partition wall 23 for partitioning each of the cylindrical cavities 21a, 22b, 21b is erected so as to abut the partition wall 13 of the movable mold plate 10. . It is desirable that the cavity partition walls 13 and 23 formed as described above are made as thin as possible in strength by hardening a steel material for a mold by heat treatment or the like.

Next, a support shaft 1s integrally connected to the columnar support shaft portion 1a formed by the cavities 11a and 21a is penetrated through the other cylindrical shaft insertion portions 1b and 2b to protrude therefrom. The slide cores 31 are fixed to the fixed mold 2 as described above.
It is mounted on the movable mold plate 10 by engaging with the finger pins 30, 30 inserted therethrough. This slide core 31, 3
Reference numeral 1 denotes a mold closing process of a mold;
It has cylindrical cores 31a, 31a that pass through 2b, 22b and reach the ends of the cavities 11a, 21a. Then, the inner diameter holes 31c, 3c of the cylindrical cores 31a, 31a are formed.
1c is a cavity for molding the support shafts 1s, 1s, and the thick portions 31b, 31b of the cylindrical cores 31a, 31a form gaps 1c, 2c between the support shaft 1s and the cylindrical shaft insertion portions 1b, 2b. Also, the cavity partition walls 13 and 23 abut against the outer peripheral edges of the cylindrical cores 31a and 31a to separate the respective cylindrical cavities, and the shaft support portion 1a and the shaft insertion portion 1
b and 2b can be separated and molded.

When plastic is injection-molded into the mold having the above structure, the molten resin is filled into the cavity from the gate G, and the pair of blades 1 and 2, the columnar shaft support 1a, and the shaft insert 2 are formed.
b, 1b and the support shaft 1s are formed in one shot. Next, when the mold is opened, the slide cores 31, 31 slide outward (left and right in the drawing) of the mold by the inclined finger pins 30, 30, and the cylindrical cores 31a, 31a are moved into the cavities 12b, 22b, 11b, 21b so that the molded product can be taken out at right angles to the mold surface. In this way, the two blades are
The hinge is molded in the engaged state by s. Further, when the mold is closed again, the slide cores 31, 31 slide toward the center of the mold by the finger pins 30, 30, and the tips of the cylindrical cores 31a, 31a reach the end faces of the shaft support cavities 11a, 21a. It becomes ready for plastic injection.

[0010]

The integrally formed hinge obtained by molding as described above is different from the conventional one, and is manufactured in a completed form without the necessity of assembling work such as insertion of a rotating part into a shaft. Is reduced.

The hinge of the present invention is not limited to the hinge (hinge) shown in FIG. 1, but may be used for hinges of various articles such as a hinge for connecting a frame R and a string F of the glasses shown in FIG. It can be molded as one piece.

Conventional plastic hinges have been formed by forming a plate-like bent portion using polypropylene, but the hinge of the present invention uses polyamide, polyacetal, or other engineering plastics having excellent strength and sliding performance. It is considered that the plastic hinge can be applied to a product requiring strength.

[Brief description of the drawings]

FIG. 1 is a plan view of a hinge showing an embodiment of the present invention.

FIG. 2 is a bottom view of the hinge of FIG. 1;

FIG. 3 is a perspective view showing a main part of a molding die for performing integral molding.

FIG. 4 is a perspective view showing a main part of a slide core of a mold.

FIG. 5 is a perspective view of a main part of one embodiment used as a hinge of glasses.

[Explanation of symbols]

 1, 2 Blade plate 1a Shaft support 1b, 2b Shaft insertion portion 1s Support shaft 10 Movable mold 11, 12 Blade plate cavity 11a, 21a Shaft support cavity 13, 23 Cavity partition wall 11b, 21b, 12b, 22b Shaft insertion Part cavity 20 Fixed side mold 30 Finger pin 31 Slide core

Claims (1)

(57) [Claims] 1. A pair of blades engaging with adjacent end surfaces of a pair of blades.
A plurality of columnar support portions and several shaft insertion portions are protruded, and a support shaft that penetrates the center axis of the shaft insertion portion is integrally formed in the columnar support portion and the shaft insertion portion is rotated. A method of manufacturing a plastic hinge, wherein the plastic hinge is formed so as to be movable.