JPH02147210A - Plastic molding tool - Google Patents

Abstract

PURPOSE:To manufacture with ease a complicated facial form of a cavity mold and lengthen, the life of a molding tool, by a method wherein the cavity mold and a core mold are made respectively of ceramics and a metal. CONSTITUTION:A pipe 4 made of resin of a combustible material is arranged within a gypsum mold 7, then molding is performed by casting ceramics of alumina within the gypsum mold 7, then the pipe 4 of the combustible material is burnt by firing the same after molding, which is gasified and a temperature controlling hole 3 of a cave is formed within the ceramics. A cavity mold 1 made of the ceramics which is molded in this manner and a core mold 2 made of a metal are fitted respectively to a fixed head die plate 5 and moving head die plate 6. The cavity mold 1 made of ceramics is free from difficulty in machining as compared with the cavity mold made of the metal and capable of performing manufacturing at a drastically low cost and obtains very smooth surface roughness also. Since the core mold 2 is made of the metal, machining which is ascribable to a dividing/pulling out device is performed as usual.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a mold for plastic molding, especially a mold for producing a large number of plastic products, or a mold for producing plastic products in which the surface has a WL rough shape or pattern. Concerning types useful as types.

(Prior Art) Conventional plastic molding molds, both the cavity type and the core type, are made of metal, and their surface shapes and patterns are machined using precision processing machines.

(Problem to be solved by the invention) With this conventional metal mold, manufacturing of complex shapes and patterns is difficult and expensive as it requires machining mainly through cutting. If they were produced in large quantities, there was a problem in that the surface wear of the cavity would be great and the service life would be short. In addition, the temperature adjustment holes in the mold must be drilled from several directions and some of them must be closed off with plugs or the like, resulting in a time-consuming process.

The object of the present invention is to solve the above-mentioned problems of conventional plastic molding molds, to have excellent wear resistance and corrosion resistance, and to have a long lifespan, and to easily manufacture molds with complex shapes and patterns and holes for temperature adjustment. The aim is to provide a mold for plastic molding that can be done.

(Means for Solving the Problems) The gist of the present invention that solves the problems is as follows: 1) In a plastic molding mold, the cavity mold is made of ceramic;
2) A mold for plastic molding according to claim 1, wherein the core mold is made of metal. 2) The mold for plastic molding according to claim 1, wherein the cavity mold is manufactured into a desired shape by a ceramic molding method such as injection molding or pressure casting molding. ) Claim 1 or 2, wherein the tube is formed by arranging a tube made of a combustible material in a ceramic, molding the ceramic, and firing it.
In the plastic mold described.

(Function) In this invention, since the cavity mold is made of ceramic, ceramic molding methods such as injection molding and pressure casting molding, which are easier to create shapes and surface patterns than machining, can be used, and complex surface shapes and patterns can be created. V-shaped ones can be easily manufactured. It is also possible to mass produce a cavity type.

Since the cavity mold is made of ceramic, it has the excellent wear and corrosion resistance properties of ceramic, and has a lifespan approximately three times longer than that of a metal mold.

Furthermore, forming the temperature adjustment hole can be done by placing a tube of flammable material inside the ceramic, molding the ceramic, and burning it to form a cavity for the temperature adjustment hole inside the cavity mold. , the hole can be easily formed. Also, the shape of the hole can be changed freely.

(Example) Examples will be described below based on the drawings.

This example is an example in which alumina ceramic is used for the entire hollow mold (1), and a pressure casting method is used to form the cavity mold.

FIG. 1 is a sectional view showing the plastic molding mold of this embodiment, FIG. 2 is an explanatory view showing the state during plastic injection molding, and FIG. 3 is an explanatory view showing the molding method of a ceramic cavity mold. In the figure, (2) is a metal core type, (3) is a temperature adjustment hole, (4) is a resin tube made of flammable material, (5) is a fixed side mounting plate, and (6) is a movable side mounting plate. be.

In this example, a resin tube (4) made of combustible material is placed inside a plaster mold (7) shown in Fig. 3, then alumina ceramic is injected and molded, and then fired after molding. The tube (4) made of combustible material is burned and gasified to form a hollow temperature adjustment hole (3) in the ceramic.

Ceramic cavity mold ('l) formed in this way
is attached to the fixed side mounting plate (5), and the metal core type (2) is attached to the fixed side mounting plate (5).
is attached to the movable side mounting plate (6) (see Figure 1).

FIG. 2 shows the molding state in which the cavity mold +1) and the core mold (2) are fitted together, and water at a desired temperature is passed through the temperature adjustment hole (3) and plastic is injected.

The ceramic cavity mold (1) of this example had less difficulty in machining than the metal cavity mold, and could be manufactured at a much lower cost, and had a very smooth surface. . Since the core mold (2) is made of metal, mechanical work caused by the dividing/extracting device can be performed as before.

Using the mold of this example, 50,000 molded products of ABS resin (8) were produced, and the wear of the ceramic recesses of the cavity mold and the surface finish of the molded products were observed. As a result, compared to metal, the wear of the four parts was about three times as many times as the same wear state, and a significant improvement in wear resistance was observed. Also, the surface finish of 9 degrees was good with natural surface roughness.

(Effects of the Invention) As described above, according to the present invention, the cavity mold is made of ceramic and the core mold is made of metal, thereby greatly improving the wear resistance and corrosion resistance as a plastic molding mold. We were able to extend the mold life. In addition, it is easy to manufacture the complex surface shapes and patterns of the cavity type, and in the case of the cavity type, in which combustible tubes are placed and molded in ceramic, it is extremely easy to form holes for temperature adjustment, making it a low-cost product. The mold can be provided.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an embodiment, FIG. 2 is an explanatory view showing the state during plastic molding, and FIG. 3 is an explanatory view showing the molding method of the cavity mold. (1): Cavity type (2): Core type (3
): Temperature adjustment hole (4): Pipe made of flammable material (5)
: Fixed side mounting plate (6): Movable side mounting plate (7) Two plaster type Patent applicant: Daishin Giken Co., Ltd. Agent: Sho Toshima, Department 4

Claims (1)

[Scope of Claims] 1) A mold for plastic molding, characterized in that the cavity mold is made of ceramic and the core mold is made of metal. 2) The mold for plastic molding according to claim 1, wherein the cavity mold is manufactured into a desired shape by a ceramic molding method such as injection molding or pressure casting. 3) Claim 1 or 2, wherein the tube is formed by arranging a tube made of a combustible material in a ceramic, molding the ceramic, and firing it.
The described plastic mold.