JPS59197341A - Forming method of casting mold - Google Patents

Abstract

PURPOSE:To reduce the time for curing and to prevent strength deterioration and deformation by using molding sand added and kneaded with a prescribed self-curing binder and evaporating forcibly moisture. CONSTITUTION:Molding sand S added and kneaded with a binder contg. a water soluble crosslinking agent and a catalyst for reaction of said crosslinking agent is prepd. Said water soluble binder is selected from the group consisting of a saccharide, the methylolurea or methylolmelamine or a methylolalkyl. Said catalyst for reaction is selected from an org. acid and inorg. acid or the metallic salt, ammonium salt or alkanol amine salt thereof. The prepd. sand S is packed into the space formed of a pattern provided with plural vent holes communicating with the surface to the rear surface and a molding flask 5. Compressed air of an ordinary temp. is penetrated through the inside of such sand S to cure the sand S at a high speed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mold making method in which a mold is drawn using foundry sand to which a water-soluble binder has been added and kneaded.

Specifically, a water-soluble crosslinking agent selected from the group consisting of sugars, methylolated products or alkylated methylolated products of urea or melamine, and organic acids, inorganic acids, or metal salts, ammonium salts, or alkanolamine salts thereof. The present invention relates to a method of molding a mold using foundry sand to which a binder containing as an essential component the catalyst for the reaction of the crosslinking agent is added and kneaded.

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 and harmful gases in shell molding, cold box, and bardock methods, and the Problems such as corrosion 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 uses water-soluble glue as a binder, and then the molding sand is dried and hardened by suction. Publication No. 56-4342 further describes a method of filling a pre-heated model with foundry sand using water-soluble glue as a binder, and drying and hardening the Tsubame foundry sand using the heat radiated from the model. Japanese Unexamined Patent Publication No. 57-171544 discloses that after filling molding sand with water-soluble glue as a binder into a combined model, one of the models is removed and hot air is passed through the open surface to cool the molding sand. Each method of drying and curing the material is disclosed. However, in the first method, molding sand mixed with a water-soluble glue binder is heated in advance, which causes stickiness and prevents the molding sand from filling every corner of the model. In the second method, the surface of the mold dries and hardens relatively quickly, but the inside of the molding sand does not harden. <, there was a drawback that the whole was not uniform. Furthermore, the third method requires the use of hot air, which poses a problem from an energy standpoint. In addition, since the binder in all of these is water-soluble, it may absorb moisture while left standing, or
Alternatively, when used as a green mold core, there was a problem that the green mold sand absorbed moisture, resulting in strength deterioration and deformation.

The present invention has been made in view of these problems, and uses a molding agent that uses a binder that self-hardens without deteriorating in strength or deforming even if left as is. The purpose of this invention is to provide a mold manufacturing method for molding.

The present invention will be explained below based on examples.

(1) has a recess (2) on the lower surface, and the recess (2) on the upper surface.
This is a model with a plurality of ventilation holes (3) that lead to the mold (2), and on the upper surface of this model (1), there is a casting flask (5) with crosspiece members (4) installed at approximately equal pitches between the opposing side walls at the upper position. ) is placed, and in the space formed by the model (1) and the flask (5), a material selected from the group consisting of sugars, methylolated products of urea or melamine, or alkylated methylolated products is placed. a water-soluble crosslinking agent, and a catalyst for the reaction of the crosslinking agent selected from organic acids, inorganic acids, or metal salts, ammonium salts, or alkanolamine salts thereof as essential components. It is filled with sand (S) (hereinafter referred to as foundry sand) (Fig. 1).

Next, as shown in FIG. 2, foundry sand (S) is placed in the space.
The model (1) and flask (5) filled with is the hollow chamber (
The four parts (2) are attached to the ground surface of the model stand (9) with the communicating hole (8) that leads to
is placed in the communication hole (8) and the hole (1o), and when compressed air at room temperature is supplied from the air supply hole (7), the compressed air flows through the hollow chamber (6), the communication hole (8), hole (10),
It flows into the flask (5) through the four vent holes (3) extending over four parts (2), flows through the molding sand (S), promotes evaporation of moisture, and is exhausted to the outside. Harden sand (S) at high speed. After hardening the foundry sand (S) by aerating compressed air for a predetermined period of time, the supply of compressed air is stopped. Next, as shown in FIG. 3, the model (1) and the mold (S') are released.

In addition, after filling the space formed by the model (1) and the flask (5) with molding sand (S), as shown in Figure 4, the plate (13) with the communicating hole (12) ) Hole (1) on the soil surface
4) Place the molding sand (S) through the gasket (15), then cover the molding sand (S) with the cover plate (16) in an airtight manner, and supply compressed air at room temperature from the air supply hole (17). However, the molding sand (S) may be hardened at high speed by flowing through the molding sand (S). Alternatively, as shown in FIG. 5, the molding sand (S) may be filled to a required thickness according to the shape of the model (1).

As is clear from the above explanation, according to the present invention, foundry sand that has been kneaded with a binder that has self-hardening properties is used, and then compressed air is passed through the foundry sand to forcibly evaporate the moisture in the foundry sand. As a result, the time required to harden the molding sand can be greatly shortened, molds can be produced efficiently, and there is no possibility of strength deterioration or deformation due to moisture absorption, and energy savings are achieved. This yuzu has the effect of being useful for the industry and has good disintegration properties, and its contribution to the 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 cross-sectional views showing other embodiments and examples of the present invention. Figure 1 Mine 3ε Figure 2 Mine 44 Figure Rod 5

Claims (1)

[Claims] A water solution selected from the group consisting of sugars and methylolated products or alkylated methylolated products of urea or melamine is placed in a space formed by a mold having a plurality of ventilation holes communicating from the surface to the back side. The foundry sand is mixed with a binder containing as essential components a crosslinking agent and a reaction catalyst for the crosslinking agent selected from an organic acid, an inorganic acid, or a metal salt, ammonium salt or alkanolamine salt thereof. A mold making method characterized in that after filling the molding sand, compressed air at room temperature is passed through the molding sand to harden the molding sand at a high speed.