JPH0745153B2 - Mold for press-fit molding of synthetic resin - Google Patents

Description

TECHNICAL FIELD The present invention relates to a molding die for molding a molded article such as a roll or a tire with a thermosetting synthetic resin such as a polyurethane resin.

[Conventional technology]

When molding molded products such as rolls and tires with conventional thermosetting synthetic resins such as polyurethane resin, the liquid resin stock solution is poured into the synthetic resin molding hollow part from the top of the mold and heated for a certain period of time. Generally, a method of demolding after curing is performed.

[Problems to be Solved by the Invention]

In the conventional method of injecting the synthetic resin stock solution into the mold from the upper part of the mold, in the process of injecting the synthetic resin stock solution, air bubbles are trapped in the stock solution or bubbles adhere to the inner surface of the mold and they are cured as they are. There is a risk that air bubbles will be contained in the product or the traces of air bubbles on the surface of the molded product will remain as dents, resulting in defects in the product.

Therefore, an object of the present invention is to provide a mold for molding a thermosetting synthetic resin molded product without entrapment of bubbles.

[Means for Solving the Problems]

In order to achieve the above object, the inventors of the present invention have conducted extensive studies, and by press-fitting the synthetic resin stock solution into the mold from the lower end of the hollow part of the molding mold so as to gently push it up,
The inventors have found that a molded product free of air bubbles can be obtained, and completed the present invention.

That is, according to the present invention, a horizontal flat plate-shaped lower die is detachably fitted to the upper surface of the lower die, and an injection passage for a synthetic resin stock solution is formed between the lower die and the injection passage. An upper mold having a synthetic resin stock solution injection hole communicating with the upper mold, one or more cylindrical outer molds vertically fitted on the upper mold and communicating with the injection passage, and an outer mold inside the outer mold. Fixing means for fixing a metal core to the inner surface of the mold with a gap therebetween, and the gap between the metal core and the cylindrical outer mold coaxially arranged in the cylindrical outer mold. The gist of the present invention is a thermosetting synthetic resin molding die in which a synthetic resin stock solution is press-fitted from below to integrally mold the metal core and the synthetic resin.

〔Example〕

Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a sectional view of an example of a mold for molding a roll made of polyurethane resin by the method of the present invention.

(1) is a horizontal plate-shaped lower mold, (2) is an upper mold fitted to the upper part of the lower mold (1), and an injection of a synthetic resin stock solution with a narrow gap between the lower mold (1) Forming a passageway (3).
(4) is a cylindrical outer mold, and is fitted on the upper mold (2) and held upright. The upper lid (5) is fitted on the upper end of the outer mold (4). A metal core (7), which is embedded in a roll (6) to be molded and integrally molded, has its lower end fitted to a disk-shaped projection (8) provided at the center of the upper surface of the upper mold (2), The cylindrical outer die (4) is loaded upright in the hollow portion. By fitting the upper holding member (9) to the upper end of the middle core (7) and fitting the upper holding member (9) into the center hole (11) of the upper lid (5), the middle core (7) ) Is accurately held in the outer mold (4) at a predetermined position coaxial with the outer mold (4), and a cylindrical gap for injecting the synthetic resin stock solution between the surface of the core (7) and the inner surface of the outer mold (4). (12) is formed.

The upper mold (2) has a resin liquid introduction hole (10) vertically penetrating from the cylindrical gap (12) between the core (7) and the outer mold (4) to the lower injection passageway (3). Are provided at several positions on the circumference, and a resin injection hole (13) communicating with the injection passage (3) from the outside is provided.

To form rolls and pipes using the above mold, the whole mold is preheated to a predetermined temperature, and a liquid synthetic resin stock solution obtained by mixing two kinds of reaction solutions of polyurethane resin is injected into the resin injection hole (13 ) Through the injection passage (3) between the upper mold (2) and the lower mold (1) and the resin liquid introduction hole (10) penetrating the upper mold (2), and around the core (7). It is injected by gently pushing it up from its lower end into the hollow portion formed by the cylindrical gap (12), and the synthetic resin stock solution is filled in the cylindrical gap (12).

After the resin stock solution is poured, the roll is integrally molded by maintaining the predetermined curing temperature for a certain period of time and curing the molded resin until it does not deform, then disassembling the mold into each part and embedding the core (7). The molded resin and the resin cured in the injection passage (3) are taken out. After that, the molded product is further completely cured in a secondary curing tank maintained at a predetermined temperature, and if necessary, finish processing is performed by a cutting machine or the like.

FIG. 2 is a plan view of another mold used in the method for press-fitting a synthetic resin according to the present invention, and FIG. 3 is a sectional view taken along line AA of the same, showing a mold capable of simultaneously molding a plurality of rolls or pipes. Indicates the type. Similar to the mold of FIG. 1, it has a flat plate-shaped lower mold (1) and an upper mold (2) fitted on the upper surface thereof, and the upper mold (2) has a plurality of cylindrical outer molds (4). Fit and stand. The lower mold (1) has a center core fitting hole (14) for holding the center core (7) coaxially with the outer mold (4) with a cylindrical gap (12) in the outer mold (4). To provide. Upper mold (2) and lower mold (1) have screws (15)
Secure with.

When the synthetic resin stock solution is press-fitted from the resin injection hole (13), it passes through the flat plate-shaped injection passageway (3) between the upper mold (2) and the lower mold (1), and the respective core (7) and outer mold ( The synthetic resin stock solution is injected into each of the cylindrical gaps (12) between 4) so as to be pushed up from the lower end at the same time.

[Action]

According to the mold for press-fitting molding of the synthetic resin of the present invention, the resin stock solution is gently injected from the lower end of the molding hollow portion of the mold so as to be pushed up, and the liquid level thereof is gently raised. Therefore, as in the conventional method of injecting the synthetic resin stock solution from the upper part of the mold, the vicinity of the liquid surface is not agitated due to the impact of the drop of the liquid, and bubbles are not entrained, and defects due to bubbles inside and on the surface of the synthetic resin molded product. There is no danger of

〔The invention's effect〕

According to the press-fitting mold for synthetic resin of the present invention, it is possible to obtain a synthetic resin molded product which is free from defects due to bubbles and has excellent quality.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an example of a synthetic resin press-fitting mold of the present invention, FIG. 2 is a plan view of another embodiment of the mold of the present invention, and FIG. Is. (1) …… Lower mold, (2) …… Upper mold, (3) …… Injection passage, (4) …… Outer mold, (5) …… Upper lid, (6) …… Roll, (7)… … Core, (8) …… disc-shaped protrusion, (9) …… upper holding member, (10) …… resin liquid introduction hole, (11) …… center hole, (12) …… cylindrical gap, ( 13) …… Resin injection hole, (14) …… Center core fitting hole, (15) …… Screw.

Continuation of front page (51) Int.Cl. ⁶ Identification number Reference number in the agency FI Technical display area B29K 105: 22 B29L 22:00 30:00 (72) Inventor Kamakari Ryutaro Rokutaro Inami-cho, Kako-gun, Hyogo Prefecture No. 1183, Fugaya Toyo Tire & Rubber Co., Ltd. Hyogo Works Akashi Plant (56) References JP-A 64-16618 (JP, A) JP-A 59-91043 (JP, A) SAI 59-131813 (JP, U) Actual Kaihei 1-68813 (JP, U)

Claims (2)

[Claims] 1. A substantially flat plate-shaped lower die which is installed horizontally, and which is detachably fitted to the upper surface of the lower die and forms an injection passage for a synthetic resin stock solution between the lower die and the injection passage. An upper mold having a synthetic resin stock solution injection hole communicating with the upper mold, one or more cylindrical outer molds vertically fitted on the upper mold and communicating with the injection passage, and an outer mold inside the outer mold. Fixing means for fixing a metal core to the inner surface of the mold with a gap therebetween, and the gap between the metal core and the cylindrical outer mold coaxially arranged in the cylindrical outer mold. A thermosetting synthetic resin molding die in which a synthetic resin stock solution is press-fitted into the underside to integrally mold the metal core and the synthetic resin. 2. The injection passage is a passage having a horizontal plate-like gap, and a plurality of the cylindrical outer dies are vertically erected on the upper die above the injection passage, and a plurality of synthetic resins are simultaneously formed. The synthetic resin molding die according to claim 1, wherein the molded body is molded.