JPS59137150A - Mold forming method - Google Patents

Abstract

PURPOSE:To dry and strengthen uniformly molding sand by admitting compressed air into the molding sand from the front side of a mold so that the air flows uniformly in the molding sand. CONSTITUTION:A molding flask 4 is placed atop a pattern board 3 with a pattern provided with plural vent holes 2, and molding sand S added and kneaded with a water soluble binder is packed in the space formed of the board 3 and the flask 4. The board 3 and the flask 4 are placed atop a pattern base 8 which has internally a hollow chamber 5, is punched with a communicating hole 6 communicated with the chamber 5 on the top surface and is provided with a feed hole 7 on the side face, and cold or heated compressed air is fed through the hole 7 into the chamber 5. The air flows through the chamber 5, the hole 6, the hole 9a, a recess 1 and the holes 2 into the sand S, thereby drying and curing effectively and successively the sand S from the surface of the mold in the direction of the top surface and thus drying and hardening uniformly the sand over the entire part thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for making a mold using foundry sand mixed with a water-soluble binder.

In recent years, there have been problems with the disposal of used foundry sand, the high price of synthetic resin binders, and problems such as the generation of foul-smelling gases and harmful gases and the corrosion of these devices in the shell molding method, cold box method, hardx method, etc. Problems such as these are occurring. To this end, molding methods using water-soluble glue or the like as a binder have recently been proposed.

For example, JP-A-53-19923 discloses a method in which a model is filled with molding sand that has been heated in advance and mixed with a water-soluble binder, and then the molding sand is dried and hardened by suction.
Furthermore, JP-A No. 56-4342 discloses a method in which foundry sand mixed with a water-soluble binder is filled into a preheated model, and the foundry sand is dried and hardened by the heat radiated from the model. However, each technology has been disclosed. However, the former method has the drawback that the molding sand mixed with a water-soluble binder is heated in advance, which causes stickiness and prevents the molding sand from filling every corner of the model. There were problems such as easy evaporation of water and difficulty in keeping the moisture constant.

In the latter method, the surface of the mold dries and hardens relatively quickly, but it is difficult to harden the inside of the molding sand, which has the disadvantage that the entire mold is not uniform. In addition, since the model had to be made into an expensive mold, the cost of the mold became high, creating an economical problem.

The present invention has been made in view of these problems, and includes adding a water-soluble binder to a space formed by a mold plate with a model equipped with a plurality of ventilation holes and a casting flask. After filling the kneaded foundry sand, room temperature or heated compressed air is vented into the foundry sand from the surface side of the mold through the ventilation holes, thereby uniformly drying and hardening the entire foundry sand. The purpose is to provide

The present invention will be explained below based on examples.

As shown in Fig. 1, the upper surface of a model board (3) with a model has a recess (1) on the back surface and a plurality of ventilation holes (2) communicating with the recess (1) from the surface. , the flask (4) is placed, and in the space formed by the model plate with model (3) and the flask (4), roasted dextrin, oxidized starch, alpha starch, starch ester, starch ether, Foundry sand (S) mixed with water-soluble binders such as high amylose (hereinafter referred to as
The molding sand (S) is filled to a predetermined density, and the molding sand (S) is leveled so that it is approximately flush with the upper surface of the flask (4), and then a hollow is formed inside as shown in Fig. 2. Room (5
), and has a communication hole (6) on the top surface communicating with the hollow chamber (5), and a supply hole (7) on the side surface. A model plate (3) and a flask (4) are positioned through a packing (9) with a hole (9) so that the hollow chamber (1) and the hole (9a) are aligned with the communication hole (6). After being placed, when normal temperature or heated compressed air is supplied to the hollow chamber (5) from the supply hole (7), the air flows through the hollow chamber (5), the communication hole (6), the hole (9a), and the four parts (1).
) and into the foundry sand (S) through the vent hole (2),
The foundry sand (S) is effectively dried and hardened sequentially from the surface of the mold toward the upper surface, and the entire molding sand is uniformly dried and hardened. on the other hand,
The air is discharged to the outside through the upper surface of the mold surface of the molding sand (S). After drying and hardening the foundry sand (S), as shown in the third factor, a model plate with a model (3) and the dry hardened foundry sand (S)
The flask (4) holding the mold is released from the mold to complete molding.

Further, in the above embodiment, ventilation of room temperature or heated compressed air may be stopped midway, and the unhardened portion of the molding sand on the upper surface side of the molding sand may be removed to provide a backup type as shown in FIG.

Further, as shown in Fig. 4, molding sand (S) is filled to the required thickness according to the model shape of the model plate (3) with model, and then the molding sand (S) is dried and hardened in the same manner as above. However, a backup type as shown in FIG. 5 may be used.

From the above explanation, it is clear that according to the present invention, foundry sand can be dried and hardened uniformly and effectively, and only a small amount of air is needed to dry and harden the foundry sand. In addition, because room-temperature or heated compressed air is introduced into the molding sand from the surface side of the mold so that it flows uniformly through the molding sand, advanced technology is not required to set the position of the ventilation holes. It has a powerful effect and its contribution to this type of industry is significant.

[Brief explanation of the drawing]

Figures 1 to 3 are process diagrams showing embodiments of the present invention;
5 and 5 are process diagrams showing another embodiment of the present invention. (Mine 3) Figure 4, Figure 5

Claims (1)

[Claims] After filling the space formed by the casting flask and a molding plate with a plurality of ventilation holes communicating from the front surface to the back surface with molding sand mixed with a water-soluble binder to a predetermined density, A method for making a mold, which comprises blowing room temperature or heated compressed air into the molding sand from the surface side of the mold through the ventilation holes, thereby drying and hardening the molding sand.