JPS589740A - Mold coating method into multiple layers - Google Patents

Abstract

PURPOSE:To prevent the cracking of coating films and the burning of molds by applying multiple layers of thick mold coatings of different kinds on patterns and packing molding sand contg. a binder on the surfaces thereof then hardening the sand by heating. CONSTITUTION:Thick mold coating layers consisting of three layers; a zircon type mold coating layer 2, a magnesia type mold coating layer 3 and a graphite type mold coating layer 4 are coated successively on a wooden pattern 1. Each layer is about 2mm. thick, and the entire patt is about 6mm. thick. Molding sand contg. an inorg. or org. type binder is packed on the mold coating layers, and further microwave electromagnetic waves are irradiated to the entire part. Then the mold coats are transferred to a mold 5 and further the mulled sand in the mold 5 hardens. Since the mold coating materials can be transferred in sufficient amt. to the mold 5 by the above-mentiond method, burning is prevented, and the cracking of the mold coats on the mold 5 when they are brought into contact with molten metal is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION Marriage molding agents are originally highly fire resistant and are expected to form a dense and strong coating film on the mold surface. In addition, if high-temperature casting materials such as special steel are used in a pot, for example, silica sand is used as an aggregate, even if the same coating mold is applied as before, a product with a low melting point will form at the interface between the molten metal and the mold. It forms a reactant (fayalite), which further penetrates into the interstices of the sand grains and reacts with the sand grains, causing casting.

Therefore, as a method to prevent such seizing, measures have been taken to prevent the phosphorous layer, mainly by replacing the silica sand as an aggregate with silica sand and improving the so-called foundry sand. However, if low-grade silica sand can be used in products such as special steel, and if it is possible to prevent molding, it will definitely contribute greatly to resource and labor savings. In addition, □゛Even if chromite sand is used, products that require ultra-high temperature casting or large steel products can only be coated with a cram-type film to a certain thickness, so products with no casting deposits are not available. The current situation is that many defects are caused. Furthermore, one of the causes of this sticking is that when the molten metal comes into contact with the casting W, cracks are generated in the coating mold, and the molten steel inside and outside the mold connects and permeates through the cracks.

In view of the above, the present invention provides a model with a thick coating of multiple layers using different coating agents in order to freely thicken the coating layer, and molding sand containing a binder is applied to the model. fill the surface,
It is characterized by heating the entire portion. The heating method is a multi-layer coating mold applied to the model by using a microwave, -p irradiation, dryer, etc.
When coating a model, the thickness of the coating layer can be freely controlled) and is transferred to the mold surface to prevent burning. t7'h% Such a layer that thickens the coating film also prevents the occurrence of cracks and is extremely advantageous as a countermeasure against defects.

As the plurality of coating layers, a coating layer based on silica, a coating layer based on graphite, a coating layer based on zircon, a coating layer based on 1 gnesia, etc. are used.

The foundry sand may be any organic or inorganic caking agent.
Furthermore, there are no restrictions such as environmentally kneaded sand or self-hardening sand, and it has the characteristics of dry transfer of multilayer eyelid type and bonding at the same time, and satisfies the requirements for one casting.

Example! , Graphite-based, diμcon-based,
A thick layer of magnesia-based paint is applied to the eyelids one after another. The thickness of each layer is approximately 2cm, and the total thickness of the binding 1 is 6m. All of the binders for coating molds are the same as those commonly used in the past.

After this coating work is completed, the layer 1119 is filled with mixed wire foundry sand containing an organic/inorganic binder.

Next, after the work is completed, the entire structure including the towing model is irradiated with microwave electromagnetic waves using III for 60 seconds. This activates the molecular movement of the eyelid mold itself, and the eyelid mold is transferred to the mold by the heat exchange effect, and the kneaded sand in the mold is further hardened.

Since this invention is configured as described above, it is possible to transfer a sufficient amount of the mold coating agent onto the mold, prevent baking, and further prevent cracks when P1!1 on the mold comes into contact with the molten metal. It can be eliminated.

These effects cannot be achieved simply by increasing the thickness of one type of coating layer. For example, in the case of a cast steel mold, the graphite coating layer can be placed as the innermost layer to prevent the introduction of carbon into the cast steel, allowing the entire layer to be thicker while still maintaining fire resistance. The Zil 1F layer has the advantage that the high cost of the material can be covered by the combined use of other coating agents.

Furthermore, in this invention, dehydration and hardening of the mold can be performed at the same time.

[Brief explanation of the drawing]

Broom 1 Figure 1 is a sectional view showing a mold setting situation according to the present invention. (1)...Wood mold (2)...Zircon type coating layer■
...Magnesia-based coating layer (4)...Graphite-based coating layer (5)...Mold, ゛zo, pu(j

Claims (1)

[Claims] A multi-layer #11 type method, which is characterized in that a plurality of thick coating molds with different coating agents are applied to the model, the surface of the molding sand is filled with molding sand containing a caking agent, and the entire layer is heated.