JPS6353899B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a cast product having an uneven pattern.

Conventionally, in order to produce cast products with uneven patterns, especially when the uneven patterns are complex, the specified uneven patterns are carved in advance into model materials such as wooden molds or metal molds, and by using these model materials, the uneven patterns can be created. It was used to manufacture cast products, but engraving complex patterns on model materials requires a great deal of time and effort, and it is not cost-effective to do anything other than produce large quantities of cast products. It was difficult to form a complex uneven pattern with a small number of cast products.

This invention focuses on the fact that foamable synthetic resins such as styrofoam, urethane, etc. can be easily melted by organic solvents such as thinner or heat from heating elements such as a baking iron, and can easily form uneven patterns on the surface of the styrofoam body. Then, we manufacture cast products using these patterned Styrofoam bodies as model materials.
The object of the present invention is to provide a method for manufacturing a cast product that eliminates the above-mentioned drawbacks. Embodiments of the present invention will be described in detail below based on the drawings.

That is, the first step is to form a predetermined uneven pattern on the surface of the foamable synthetic resin body 1 while dissolving the foamable synthetic resin using an organic solvent, a heating element, or the like.

As the foamable synthetic resin body 1, a foamed polystyrene plate, a foamed urethane plate, or the like is used, and the thickness of the final cast product corresponds to the thickness of the foamed polystyrene plate or the like. Thinner or the like is used as the organic solvent, and a heating iron or the like is used as the heating element. By applying or pressing these onto the surface of the Styrofoam board, the surface of the Styrofoam board is dissolved. An uneven pattern a is to be formed, and since the styrofoam plate is extremely easily dissolved with thinner, a baking iron, etc., any complicated uneven pattern can be easily formed.

Styrofoam has excellent flexibility, so it can be formed into curved surfaces in addition to flat surfaces to form patterns, and it can also be made into three-dimensional shapes by cutting the polystyrene into the required shape and pasting the cut pieces together. It is also possible to construct it into a model material.

In the second step, the foamable synthetic resin is patterned in the first step in organic self-hardening molding sand 2 mixed with a sand binder containing an organic solvent capable of causing the foamable synthetic resin body 1 to undergo reaction shrinkage. The body 1 is buried, and a mold with a back pattern is formed by caking and hardening of the molding sand, and at the same time, the organic solvent in the sand binder and Styrofoam are gradually reacted, and the Styrofoam is dissolved and made into a liquid. The mold 3 is completed by releasing the contracted foamable synthetic resin body.

Examples of sand binders containing organic solvents include furan,
It uses phenol, urethane, and other modified resins, and creates organic self-hardening molding sand by adding 1 part of sand binder to 100 parts of sand, and the sand binder is the same. The organic solvent in the binder and Styrofoam are gradually reacted, and the Styrofoam is dissolved and liquefied while shrinking.

In the same mold 2, the foamed polystyrene on which the uneven pattern a was formed in the first step is buried, and the back side pattern opposite to the pattern a is formed by caking and hardening of the molding sand with the sand binding agent.
In addition to molding a mold with a', the Styrofoam is melted and shrunk by reacting with a sand binder.In order to proceed with this reaction, the mold must be left in place for about 1 to 2 hours after the casting. The Styrofoam must be left buried in the sand 2.

In other words, the shrinkage effect of Styrofoam caused by the sand binder has a time lag with the self-hardening effect of the molding sand caused by the sand binder, and the self-hardening effect of the molding sand occurs first, followed by the shrinkage of the Styrofoam. The organic solvent for the sand binder is selected and the mixing ratio with the sand is specified so that the effect occurs.

After the mold with the back pattern a' is molded, the contracted Styrofoam is easily released, and the mold 3 is completed.

The third process is the back pattern completed in the second process.
Molten metal is poured into the mold 3 of a' and solidified, and a cast product 4 is extracted from the mold.

This invention has the following effects.

In other words, the main point of the present invention is to use a foamable synthetic resin body, form a complex uneven pattern on the same synthetic resin body with an organic solvent or a heating element, and use a sand binder containing an organic solvent to form molding sand. Since the mold is released by melting and shrinking the synthetic resin inside, the foamable synthetic resin is highly flexible, so it is easy to release the mold even on a reverse gradient, so special consideration should be given to the draft angle of the mold. In addition, the foamable synthetic resin body has sufficient strength to withstand sand pressure, and furthermore, after the initial strength of the mold of organic self-hardening molding sand is obtained, the binder in the molding sand is The contained organic solvent gas gradually reacts with the foamable synthetic resin body, shrinking the synthetic resin body and creating a gap at the contact surface with the mold, making mold release extremely easy and complicated. It can easily and reliably produce patterns with reverse slopes, has excellent reproducibility of complex patterns, is suitable for manufacturing small quantities of cast products, and is economical with fewer steps than conventional processes. It has the effect of being able to be manufactured.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of each step in the method of the present invention. FIGS. 2 to 4 are explanatory diagrams of various patterns in the arrow direction view of FIG. 1. 1: foamable synthetic resin, 2: molding sand, 3: mold,
4: Cast product, a: Uneven pattern, a′: Back pattern.

Claims (1)

[Claims] 1. First step of a method for manufacturing a cast product with an uneven pattern, which comprises the following steps: A predetermined uneven pattern is formed on the surface of a foamable synthetic resin body while melting the same with an organic solvent, a heating element, etc. The process of forming. Second step: embedding the foamed synthetic resin body with the pattern formed in the first step in organic self-hardening molding sand mixed with a sand binder containing an organic solvent that can react and shrink the foamable synthetic resin body; A process in which a mold with a back pattern is formed by hardening the molding sand, and the mold is completed by releasing the foamable synthetic resin body that has shrunk due to the organic solvent in the sand binder. Third step: Pour the molten metal into the mold of the second step, and after solidifying,
The process of extracting a cast product from a mold.