JPH1034664A - Mold for vulcanization of rubber molded article and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease manufacturing cost of a mold for vulcanization a rubber molded article. SOLUTION: In a mold for vulcanization of a ruber molded article wherein a vent piece 7 with an outer diameter of 2.0-4.0mm is inserted into an opening part on the inner face side of the mold of vent holes 4 and 5 communicated with the inner and outer faces of the mold 1 and a vent hole 8 with a hole diameter of 0.1-1.0mm is penetrated through this vent piece 7 in the axial direction, the vent piece 7 is prepd. by cutting a drawn aluminum pipe into a specified length.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an air vent in an axial direction at an opening of an exhaust hole for discharging gas remaining between a rubber molded product and a mold on the inner side of the mold. A rubber molded product vulcanizing mold in which a rubber material flows out into a vent hole by mounting a vent piece, and a protrusion formed on the surface of the rubber molded product is easily cut at the time of mold release, and a method of manufacturing the same. About.

[0002]

2. Description of the Related Art Generally, when a rubber molded product such as a tire is vulcanized by using a mold, air or other gas remains between the rubber material charged in the mold and the inner surface of the mold. In addition, since the residual gas forms a defective portion based on poor vulcanization on the surface of the rubber molded product, the conventional mold has an exhaust hole communicating with the inner and outer surfaces of the mold, where the gas tends to stagnate. Many holes are formed in the mold to discharge residual gas between the inner surface of the mold and the rubber molded product.

However, since the exhaust hole has a large hole diameter (usually around 2 to 3 mm), when the gas is exhausted, the rubber material easily flows out into the exhaust hole together with the gas, and the surface of the vulcanized rubber molded product is discharged. Unsuitable protrusions (spews) are formed as products. For this reason, there is a disadvantage that an extra step of cutting and removing the protrusion is required, and the molding cost is increased.

Accordingly, various proposals have been made for a mold that does not require such a process of treating protrusions. For example, a ventilation hole having a small diameter is provided in the opening on the inner surface side of the exhaust hole of the mold in the axial direction. There is a structure in which a vent piece made of a metal such as iron or a synthetic resin provided in the above is fitted.

[0005]

However, if a large number of exhaust holes are drilled at locations where gas is likely to stagnate and vent pieces are to be disposed in all of them, the total number of vent pieces becomes enormous, and depending on the mold, In this case, several hundred to one thousand vent pieces are required, and the cost required for the vent pieces is extremely high if the number of replacement pieces is added during maintenance and cleaning of the mold.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and a vulcanization mold for a rubber molded product capable of reducing the production cost of a mold by drastically reducing the production cost of a vent piece. It is an object of the present invention to provide a manufacturing method thereof.

[0007]

The rubber mold vulcanization mold of the present invention has an outer diameter of 2.0 mm to 4.0 mm at an opening on the mold inner surface side of an exhaust hole communicating with the inner and outer surfaces of the mold. 0mm vent piece is fitted, and the hole diameter of this vent piece is 0.1mm ~
A 1.0 mm ventilation hole penetrated in the axial direction,
The vent piece is obtained by cutting a drawn aluminum tube into a predetermined length. Here, "pulled aluminum pipe" refers to an aluminum pipe having a predetermined dimension drawn through a mold hole such as a die and elongated.

According to the present invention, a drawn aluminum pipe having a desired outer diameter / hole diameter and an extended length can be obtained from an aluminum pipe having an arbitrary outer diameter / hole diameter by drawing. After that, a desired vent piece can be obtained only by cutting the drawn aluminum pipe after extension into a predetermined length.

Therefore, according to the manufacturing method of the present invention, an arbitrary aluminum pipe is drawn and has an outer diameter of 2.0 mm to 4.0 mm.
After producing a drawn aluminum tube extending to 0 mm and an inner diameter of 0.1 mm to 1.0 mm, the drawn aluminum tube is cut into a predetermined length to produce a vent piece,
A mold is manufactured using this vent piece.

In the case of a conventional vent piece, first, a long columnar body having an outer diameter of 2.0 mm to 4.0 mm is cut into a large number, and each cut piece has an inner diameter of 0.1 mm in the axial direction.
A hole of about 1.0 mm had to be drilled with high precision by machine processing so that there was no gap. In this case, since the pieces are machined one by one, the production cost per piece is very high.

On the other hand, in the case of the vent piece of the present invention, the outer diameter of the vent piece can be obtained only by passing the aluminum tube through the die hole of the die or the like, and the cost of the drawing process is very low. The minute holes serving as vent holes of the vent piece are provided as relatively large holes in the aluminum tube before drawing. It is not necessary to drill holes later by machining as in the prior art. Therefore, if the present invention is used, a bent piece can be manufactured from a drawn aluminum pipe at very low cost, and the manufacturing cost per piece is very low. Also, there is no fear of hole displacement.

The drawn aluminum pipe is desirably cut by grinding. In the case of cutting with a metal cutter or laser, burrs may be formed at the cutting location and finishing processing is required after cutting, but in the case of grinding processing, there is no risk that burrs will be formed at the cutting place, and finishing is performed. This is unnecessary and leads to further cost reduction.

[0013]

FIG. 1 is a sectional view of a main part of a vulcanizing mold for a rubber molded product according to an embodiment of the present invention. FIG.
In the figure, reference numeral 1 denotes a mold. The mold 1 includes a base 2 made of iron and a large number of segments 3 made of aluminum supported by the base 2 and forming an inner surface of the mold. The segment 3 has an exhaust hole 4 that opens to the inner surface of the mold penetrating to the rear surface. The exhaust hole 4 communicates with an exhaust hole 5 that passes through the rear surface of the segment 3 and penetrates the inner and outer surfaces of the base 3.

A large-diameter pilot hole 6 is formed in the opening of the exhaust hole 4 on the inner surface side of the mold, and a vent piece 7 is fitted into the pilot hole 6. Outer diameter D ₀ of this vent piece 7
Is 3.0 mm. Further, the vent piece 7 is provided with a ventilation hole 8 penetrating in the axial direction. The hole diameter d ₀ of the ventilation hole 8 is 0.8 mm.

The mold according to the present invention is manufactured as follows. The ventilation holes 4 and 5 are formed in the base 2 and the segment 3. A pilot hole 6 is formed in the ventilation hole 4 of the segment 3.
In parallel with this, the vent piece 7 is manufactured. First, an aluminum tube having an arbitrary outer diameter, hole diameter, and length is prepared, and the aluminum tube is drawn through a die hole of a predetermined die to produce a drawn aluminum tube 9 (see FIG. 2). This drawn aluminum tube 9 has an outer diameter D ₁ of 3.0 mm and a hole diameter d ₁ of 0.8.
mm, the length is expanded to 1000-2000m
m. Next, the elongated drawn aluminum tube 9 is cut at a pitch of about 15 mm. Cutting is performed by grinding. Thus, the vent piece 7 is manufactured.

The manufactured vent piece 7 is fitted into the prepared hole 6 of the ventilation hole 4 of the segment 3 from the inner side of the mold. Then, the head of the vent piece 7 is finished in accordance with the inner surface shape of the segment 3.

When a mold is manufactured by using the present invention, the manufacturing cost of the vent piece is reduced to 1/3 to 1/4 as compared with the conventional case, and it has been found that the mold manufacturing cost can be greatly reduced.

[0018]

According to the present invention, it is possible to greatly reduce the cost of manufacturing a metal mold as compared with the related art.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part of a mold for vulcanizing a rubber molded product according to the present invention.

FIG. 2 is a side view and a front view of a drawn aluminum tube,

FIG. 3 is a side view of a vent piece.

[Explanation of symbols]

1 mold 2 base 3 segments 3 4,5 exhaust hole 7 ventlid 7 9 drawn aluminum tube D _0, D ₁ outer diameter d _0, d ₁ pore size

Continued on the front page (51) Int.Cl. ⁶ Identification number Reference number in the agency FI Technical display location B29K 105: 24

Claims (3)

[Claims] 1. A vent piece having an outer diameter of 2.0 mm to 4.0 mm is fitted in an opening of an exhaust hole communicating with the inner and outer surfaces of the mold on the inner surface side of the mold. .1
In a vulcanizing mold for rubber molded articles provided with a ventilation hole of 1.0 mm to 1.0 mm in the axial direction, the vent piece is formed by cutting a drawn aluminum tube into a predetermined length. Mold for vulcanization of molded products. 2. A method for vulcanizing a rubber molded product according to claim 1, wherein an aluminum pipe having a predetermined size is drawn in advance to have an outer diameter in a range of 2.0 mm to 4.0 mm.
A vulcanized rubber molded product characterized by producing a drawn aluminum tube extending to an inner diameter of 0.1 mm to 1.0 mm, and cutting the drawn aluminum tube to a predetermined length to produce a vent piece. Manufacturing method of metal mold. 3. The method according to claim 2, wherein the drawn aluminum pipe is cut by grinding.