JPH042336B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a mold for forming a fugitive model used in precision casting.

(Conventional technology and issues) Conventionally, molds for precision casting fugitive models using pour-in fugitive model materials such as naphthalene-based model materials and urea-based model materials require machining of plaster female molds or blank surfaces. Aluminum molds are used to form molding cavities, but female plaster molds are bulky and have poor thermal conductivity.
In addition, they have the disadvantage of being easily damaged, while those made of aluminum, although the above-mentioned disadvantages are relatively improved, have the disadvantage of increasing processing costs and high costs.

The present invention was made in view of such problems, and an object of the present invention is to provide a mold for forming fugitive models that is lightweight, has good thermal conductivity, is easy to manufacture, and can reduce manufacturing costs. shall be.

(Means for Solving the Problems) The mold of the present invention, which has been made to achieve the above object, has a molding cavity 5 formed in the center of the mating surfaces of the upper mold 3 and the lower mold 4, which can be assembled in parts. In the fugitive model forming mold, the upper mold 3 and the lower mold 4 are formed into a shell shape by a copper layer formed by electroforming.

(Function) Since the upper mold and the lower mold are formed into a shell shape using a copper layer, they are lightweight and have extremely excellent thermal conductivity.
Therefore, the model material injected into the molding cavity can be rapidly solidified and cooled. In particular, since the model material in contact with the inner surface of the molding cavity is rapidly cooled, the model surface can be made to have a dense structure. Disappearance after cooling Even after the model is removed from the mold, the mold is lightweight and retains little heat, so it quickly cools down to room temperature, resulting in a decrease in the cooling capacity of the mold even after repeated use. Never.

Further, since the copper layer forming the shell-like upper mold and lower mold is formed by electroforming, it can be manufactured extremely easily regardless of the shape of the molding cavity.

(Example) The present invention will be described below along with a mold for forming a fugitive model 1 for a turbine blade as shown in FIG. 1 and a manufacturing method thereof.

First, in order to make the mold for this model 1,
The master mold for electroforming is prepared. In other words, in the case of the model 1 which is divided into upper and lower parts on the C plane as shown in FIG.
A set of upper and lower molds is formed in advance. Fig. 2 shows a mother die 2 for manufacturing the upper mold formed corresponding to the shape of the upper half (the B-B arrow plane in Fig. 2 is the A-A arrow plane in Fig. 1). (corresponds to the position of the surface). Matrix 2
consists of a convex portion 2a having a shape corresponding to the upper half of the model 1, and a flat portion 2b continuous with the convex portion 2a and provided around at least three circumferences of the convex portion 2a. The master mold 2 is made of plaster, reinforced plastic, cast aluminum, or any other material.

The electroforming mother mold 2 formed into a predetermined shape is subjected to a conductive treatment on the convex portions 2a and the flat portions 2b, and then, together with the copper material for the consumable electrode, is bathed in a plating bath of copper sulfate or copper borate solution, etc. The electrode is immersed in the copper material, and electricity is applied between it and the electrode copper material. Then, due to the action of the battery, the copper separated from the consumable electrode is transferred and electrodeposited on the surface of the mother mold in a layered manner, and after a certain period of time, a copper layer of several mm to more than 10 mm is formed on the surface of the mother mold. If the copper layer is peeled off from the surface of the mother mold in this state, a shell-shaped pure copper upper mold with high surface precision, whose inner surface is a faithful copy of the mother mold surface, is obtained. The lower mold is also manufactured in the same manner as the upper mold.

FIG. 3 shows a molding die in which the shell-shaped copper upper mold 3 and lower mold 4 each manufactured in this way are assembled, and the center part of the mold mating surface of the upper mold 3 and lower mold 4 is A molding cavity 5 is formed, and flange portions 3a, 4a are formed on the periphery of the molding cavity 5, and an upper mold 3 and a lower mold 4 are connected by bolts, nut clips, etc., so that they can be divided and assembled freely. .

Comparing this copper shell mold to a plaster mold, it weighs about 1/5, takes 1/5 to 1/8 the molding time, and has a semi-permanent service life.

(Effects of the Invention) As explained above, the fugitive model forming mold of the present invention has an upper mold and a lower mold formed in a shell shape by a copper layer, so it is lightweight and has extremely excellent thermal conductivity. The model material injected into the molding cavity can be quickly solidified and cooled, and since the mold retains only a small amount of heat after molding, it can be quickly cooled to room temperature, and even if used repeatedly without interruption, the cooling ability will not be lost. You can perform casting work without any trouble. In addition, the part of the injected model material that comes into contact with the inner surface of the molding cavity is rapidly cooled and the model surface becomes densely textured, which contributes to improving the smoothness and surface precision of the inner surface of the mold manufactured using the model. Therefore, a mold suitable for precision casting can be easily produced.

In addition, since the copper layer that forms the shell-like upper and lower molds is formed by electroforming, there is no need for cutting when forming the molding cavity, regardless of the shape of the molding cavity. It can be manufactured extremely easily.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing an example of a fugitive model, Fig. 2 is a sectional view showing an example of a mother mold for electroforming, and Fig. 3 is a sectional view of a mold for forming a shell-shaped fugitive model according to an example. be. 1... Erasable model, 2... Mother mold for electroforming, 3...
Upper mold, 4...lower mold, 5...molding cavity.

Claims (1)

[Scope of Claims] 1. A fugitive model molding die in which a molding cavity 5 is formed in the center of the mating surfaces of an upper mold 3 and a lower mold 4 that can be assembled in parts, comprising: 4. A fugitive model molding die, characterized in that 4 is formed into a shell shape by a copper layer formed by electroforming.