JPS6343045Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a plastic mold suitable for molding large-sized molded products.

For example, when molding plastic using a large mold with a length of about 3600 mm and a width of 750 mm, the molding conditions are such that the mold is preheated to 80°C when pouring the metal, and cooled down to 30°C when releasing the mold. Given that its preheating and cooling takes a very long time, e.g. 30-40 minutes, thus increasing the time required for one cycle of molding and making the price of the molded article very high;
In addition, since it takes a long time to form, it has a disadvantage in mass production.

The present invention has been developed in view of the above-mentioned circumstances, and its purpose is to provide a plastic mold that significantly shortens the time required for heating and cooling, thereby reducing the manufacturing cost of molded products.

An embodiment of the present invention will be described below with reference to the drawings. Reference numeral 1 denotes a cavity manufactured by electroforming, in which a flange portion 3 is integrally extended around the periphery of a concave portion 2 having an uneven shape that matches the outer shape of the molded product. Reference numeral 4 denotes a rectangular outer frame made of a steel plate, which is fixed to the outer peripheral edge of the flange portion 3 by welding or the like. Reference numeral 5 denotes a reinforcing frame which is substantially parallel to the back side of the cavity 1 and fixed by welding or the like at regular intervals. It has a widening concave portion 7. 8
is a flow pipe made of, for example, a copper pipe or an aluminum pipe, which is housed in the concave portion 6, and a heat transfer member 9 made of, for example, aluminum is sandwiched between the flow pipe and the back surface of the cavity 1. There is. A semicircular concave portion 10 approximately equal to the outer diameter of the flow pipe 8 is provided on the lower surface of the heat transfer member 9 so that it comes into contact with the flow pipe 8 over a wide contact area. The flow pipe 8 is positioned by the groove 10 so that the flow pipe 8 is spaced apart from the left and right side walls of the groove 6 by a predetermined gap 11, respectively. Reference numeral 12 denotes a backing material filled in the outer frame 4, which is preferably made of epoxy resin or concrete. The above explanation is for the lower die of the mold, but since the upper die has a similar structure, the explanation will be omitted.

When performing cast molding using such a mold, first, before extruding the molten metal, hot oil is supplied and circulated in the flow pipe 8 to heat the cavity 1 to, for example, 80°C, and then , the molten metal is extruded, and as soon as the supply of the molten metal into the cavity 1 is finished, the supply of hot oil into the flow pipe 8 is stopped and cooling water is supplied instead, so that the temperature of the cavity 1 reaches, for example, 30°C. When the temperature drops, the mold is opened and the molded product is taken out.

The configuration of this embodiment provides various excellent practical effects as described below. That is, the flow pipe 8 has a large contact area and is in contact with the heat transfer member 9 made of aluminum material, which has higher thermal conductivity than the reinforcing frame 5, and the thermal resistance between it and the cavity 1 is extremely small. Since the reinforcing frame 5 is only in line contact, the thermal resistance is extremely high, and the gap 11 existing between the flow pipe 8 and the grooved portion 6 acts as a heat insulating layer. The heat from the hot oil supplied into the tube 8 is extremely efficiently transmitted to the cavity 1 via the heat transfer member 9, but on the contrary, it is hardly transmitted to the reinforcing frame 5, and the cavity 1 is rapidly preheated. Become so. Furthermore, lining material 1 of cavity 1
Since 2 is made of epoxy resin or concrete and has good heat retention properties and prevents heat radiation from the cavity 1 as much as possible, the time required to preheat the cavity 1 is greatly shortened in general, and cooling water is similarly supplied into the flow pipe 8. Even in such a case, the cavity 1 can be cooled in an extremely short time, and the time required for one cycle of molding can be greatly shortened. That is, length 3600mm, width
Even with a large mold of about 750 mm, it takes 5 to 6 minutes to preheat from 30℃ to 80℃ and about 4 minutes to cool from 80℃ to 30℃, which reduces the time required for one molding cycle compared to conventional structures. Therefore, the manufacturing capacity can be increased six times.

Further, although the cavity 1 has a tendency to be easily distorted due to the heat from the flow pipe 8 in the portion close to the flow pipe 8, the flow pipe 8 is located within the concave portion 6 of the reinforcing frame 5, and the cavity 1 Since the reinforcing frame 5 is located at a position where distortion is most likely to occur, distortion of the cavity 1 is prevented as much as possible and high dimensional accuracy can be maintained.

Furthermore, if concrete is used for the backing material 12, the material cost will be low and the heat retention will be sufficiently high, making it very economical.

As is clear from the above description, the present invention is suitable for reducing costs by shortening the molding cycle of large molded products, and is also suitable for mass production. A plastic mold suitable for various molding methods can be provided.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, with FIG. 1 being a longitudinal sectional view and FIG. 2 being an enlarged longitudinal sectional view of the main parts. In the drawing, 1 is a cavity, 4 is an outer frame, 5 is a reinforcing frame, 6 is a grooved part, 8 is a flow pipe, 9 is a heat transfer member, 1
2 is a backing material.

Claims (1)

[Scope of utility model registration request] A cavity is formed by electroforming, and a metal reinforcing frame is attached to the back side of the cavity. A distribution pipe that is housed in the groove and through which a heating or cooling liquid flows, and a distribution pipe that is housed in the groove and extends from the reinforcing frame so as to be in close contact with the outer surface of the circulation pipe and the outer surface of the cavity, respectively. A plastic mold made of a heat transfer material with high thermal conductivity.