JPS60166141A - Molding method - Google Patents

Abstract

PURPOSE:To form efficiently a uniform and stable casting mold by packing molding sand added with a binder to a pattern formed with a mold coating layer on the surface in contact therewith and performing simultaneously solidification of a sand mold and transfer of the mold coating to the sand mold by holding at an ordinary temp. CONSTITUTION:A refractory mold coating material added with a self-curable material is preliminarily coated on a pattern 1 to form a mold coating layer 2 on the surface and molding sand 3 to and with which an inorg. or org. self- curable binder is added and mixed is packed into the pattern 1 in contact therewith. The sand 3 and the pattern 1 are then held at an ordinary temp., by which the solidification of the mold 3 and the transfer of the mold coating 2 to the sand mold 3 are simultaneously carried out. The production of the uniform and stable casting mold having high accuracy is thus made possible by making use of the self-curing reaction without using special heat energy.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the η1 method for making molds with excellent energy saving properties.

A model with a mold coating applied to its surface is held in a frame, molding sand greened with a binder is brought into contact with the model, and then heated using an electrical heating method or a dielectric heating method using microwaves. A method has been developed in which a coating mold on the surface of a model is transferred to the surface of a sand mold, and a mold made of a sand mold is provided with a coating layer on the surface. The molds obtained in this way have been attracting attention recently because they have high precision using the TJ method and do not require much skill in molding, but they all have the following problems. In other words, in the electric heating method, (force) The heating effect depends on the distance from the electrode, so the transfer state varies depending on the location and is less reliable.

(4) If the thickness of the good conductor film (e.g. resin) for energization is not always constant, the transfer effect will vary due to the difference in current density.Also, in order to form a coating film on the model surface, advanced technology and a large amount of work will be required. It is labor intensive and inefficient.

lΦ　There is a problem in terms of safety management because electricity is applied.

L ■　The current application time required for transfer is long.

There are many problems. Furthermore, in heating methods using microwaves, the reliability of transfer is impaired due to differences in p frequencies.

・A material that is highly transparent to microwaves must be used as a model.

+i+ Equipment costs will be quite expensive.

・4) Restricted by the size of the mold.

The above problems are mainly caused by the use of thermal energy for transferring the coating mold, and there has been a strong demand for a more economical and highly practical molding method.

The present invention has been made in view of the above-mentioned circumstances, and provides a molding method that makes it possible to obtain uniform, stable, and highly accurate molds by utilizing self-hardening reactions without using special thermal energy. It is something.

That is, the mold making method according to the present invention uses a model that has been coated with a fire-resistant coating agent containing a self-hardening substance to form a coating layer on its surface, and then adds and mixes an inorganic or organic self-hardening binder. The molding sand is brought into contact with the mold, filled, and held at room temperature, thereby simultaneously solidifying the sand mold and transferring the coated mold onto the sand mold.

First, to explain this in more detail based on the drawings showing the embodiments, FIG. layer 2
is formed, and molding sand 3 is filled in close contact with this mold layer 2.

As the model 1, all commonly used models such as wooden molds and metal molds can be used. The mold coating agent constituting the mold coating layer 2 is made by adding a room temperature curable resin and a solvent to a fire-resistant aggregate such as graphite, alumina, magnesia, etc., and further adding a catalyst that acts as a curing accelerator as necessary. Those added can be used. Examples of room temperature curable resins include polyvinyl acetate emulsion, but other materials such as phenol resins, epoxy resins, alkyd resins, furan resins, and urethanes can also be used. As the solvent, for example, alcohol, water, etc. can be used.

Furthermore, as the catalyst, aromatic compounds such as sulfonic acid and inorganic acids such as phosphoric acid can be used. Examples of these combinations are as follows.

Graphite 100 parts (volume parts, referred to below) Room temperature curable resin (e.g. polyvinyl acetate emulsion) 1 to 5 parts Solvent 1-
10 parts Catalyst 3 parts A mold coating agent such as the one described above is applied to the surface of the model 1 using an appropriate coating method such as brush coating T, but before this coating 711, a suitable mold release agent ( For example, 4 cloths (for example, methane epoxy resin, varnish, tenker, etc.) are prepared.

As the foundry sand, self-hardening kneading sand to which an organic or inorganic binder (binding agent) is added is used. Examples of the blending of this kneaded sand are as follows.

A (Using an inorganic binder) Silica sand 100 parts Water glass 7 parts / Sand C1S 3 parts / Sand B (Using an organic binder) Silica sand IOO part Furaflan resin 1.5 parts / Sand hardening agent (Inorganic Acid or organic acid) 7 parts/sand Foundry sand consisting of 4 parts kelized sand was applied to the mold layer 2 as shown in Figure 1.
When it was brought into contact with Model 1 equipped with and kept at room temperature,
Approximately 1 hour for kneading sand A using an inorganic binder.
In the case of the kneaded sand B using an organic binder, the mold could be removed after being left at room temperature for about 30 minutes, and the transfer of the coating mold and hardening of the sand mold were completed. The obtained mold had a coating mold on the surface of the sand mold and had extremely high dimensional accuracy, and the surface stability was also good. The mold removal time can be adjusted over a wide range depending on the type and amount of the binder and other additives. The holding temperature may be room temperature, or appropriate heating may be performed in order to promote the reaction within a range consistent with the purpose of the present invention.

In addition, as a result of actually pouring metal using a mold manufactured by this molding method, an extremely excellent casting surface with high dimensional accuracy comparable to precision shizo was obtained. Figure 2 shows the relationship between the standing time during molding and mold strength, and Figure 3 shows the relationship between the standing time and residual moisture in the coating mold. As can be seen from these figures, a mold with excellent strength can be obtained in a relatively short period of time. Although the examples have been described above, this molding method can be applied to various other molds and coating molds that use additives that self-harden through condensation reactions or other chemical reactions.

As explained below, the mold making method according to the present invention is an excellent method that can efficiently and easily manufacture a mold having a highly accurate and stable surface. Also,
Since no special energy is required for transferring the coating mold, it is excellent in terms of economy and equipment.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of the molding method according to the present invention, Figures 2 and 3.
The figure is a graph showing the relationship between the standing time and the properties of the mold. l... Model, 2... Coating layer, 3... Foundry sand. Patent applicant Yamakawa Sangyo Co., Ltd. Agent Patent attorney Hiroshi Sugawara

Claims (1)

[Claims] (1) Using a model that has been coated with a fire-resistant coating agent containing a self-hardening substance to form a coating layer on the surface, molding sand mixed with an inorganic or organic self-hardening binder is applied to this model. A mold making method characterized by solidifying a sand mold and transferring a coated mold onto the sand mold at the same time by contacting and filling the mold and holding it at room temperature.