JPH044076A - Method for coating casting - Google Patents

Abstract

PURPOSE:To greatly improve efficiency and to prevent the dropping and splashing of coating material at the time of moving and transporting by subjecting heated castings to dip coating, thereby expediting the dryness of the coating material and accelerating the dryness of the coating material in recessed parts even if the castings have the recessed parts. CONSTITUTION:The castings of automobile parts which are produced by sand mold and have ruggedness on the surfaces are subjected to a shot blasting treatment, by which the sand on the surfaces thereof is removed. The castings heated by a heat treatment are thereafter dipped into a coating material tank contg. phthalic acid resin varnish as the coating material and are thereby coated at the point of the time the castings are cooled to about 70 deg.. The coating material on the surfaces of the castings is dried up upon lapse of 4 to 5 minutes after pulling up if the castings are pulled up from the coating material tank and are rested in the atm. The outflow of the coating material from the recessed parts on the surfaces is obviated even if the castings are turned over.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a method of coating a cast product, and more particularly to a method of dip coating.

[Conventional technology]

Conventionally, casting products (hereinafter referred to as castings) were painted by disassembling the mold, removing the foundry sand by shot blasting, and then hanging the castings on a hanger or placing multiple castings in a mesh basket. This was then dipped into the tank where the paint was stored, and the paint was applied using what is known as dobu dipping.

[Invention or problem to be solved]

However, in the above-mentioned conventional method of painting castings, paint not only scatters in the workplace, contaminating the workplace, but also poses a risk of workers getting caught in the scattered paint and falling down. In other words, castings usually have irregularities on their surface or inside, so when the item is soaked in a gutter, paint accumulates in the recesses, and the drying progress of the paint in the recesses is slow. If the casting was moved or transported before the paint had completely dried, the paint would drip from the casting, causing paint to scatter all over the work area. If an attempt is made to prevent such scattering of paint, the problem arises that the paint accumulated in the recesses of the casting cannot be moved until it dries, thereby reducing work efficiency. SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and its purpose is to provide a method for coating castings that can speed up the drying of paint.

[Means to solve the problem]

In order to achieve the above objectives, the casting coating method according to the present invention has the following features:
It is characterized by dip coating heated castings. Further, the heating is characterized by using residual heat during manufacturing of the casting or residual heat during heat treatment of the casting. In the above configuration, the casting is any casting that can be obtained using a sand mold or a metal mold. The raw material for coating is usually a rust-preventing oil such as phthalic acid resin varnish, which is used to prevent rust from castings and to add luster to the casting surface. Of course, other well-known paints can also be used. The temperature of the casting is 50-100°C. Particularly preferably, the temperature is around 70°C. The higher the temperature, the faster the paint dries, but it is considered to be within a safe temperature range without the risk of paint deterioration or ignition.6 To heat the casting to the above temperature, heat it with a well-known heater. However, since the casting is at a temperature above the above-mentioned temperature during manufacture, it is economical to apply the coating when the casting has been cooled to the above-mentioned temperature. Also, castings are sometimes heat treated to improve their material quality, and in this case, the heat treatment is also heated to a temperature higher than the above temperature, so the temperature at that time may be used. For dip painting, if the casting is large, it is hung on a hanging device, or if it is relatively small, multiple castings are placed in a mesh basket, and this is transferred to a tank where the paint is stored. This is done by immersing the fish in the dobu-zuke process.

[Effect]

In the method for coating a casting according to the present invention, a heated casting is coated by dipping. After painting, when the casting is pulled out of the paint tank, the #i surface paint is quickly dried, and the paint that has accumulated on the surface of the casting and in the recesses formed inside it is also quickly dried. 6. is used as residual heat during casting manufacturing or heat treatment.

【Example】

A casting of an automobile part weighing approximately 6 kg and having an uneven surface, manufactured by a sand mold, was subjected to sotoblasting treatment to remove sand on the surface. Thereafter, when the casting heated by the heat treatment was cooled to about 70°C, it was immersed in a paint tank containing phthalic acid resin varnish for painting. When a casting was pulled out of a paint tank and left in the atmosphere, 4.5 minutes after pulling it up, the 'a'
The paint on the surface of the garment was dry, and even when the casting was tipped over, the paint did not flow out from the recesses on the surface.

[Comparative example]

After cooling the same casting as in the above example to room temperature, it was painted by dipping using the same paint as in the above example. When 4.5 minutes had passed since the casting was lifted from the paint tank, the paint on the surface of the casting had not yet dried, and when the casting was turned over, the paint that had accumulated in the recesses on the surface flowed out. It took about 60 minutes for the paint on the surface of the casting to dry, and about 150 minutes for the paint on the recesses on the surface to completely dry.

【Effect of the invention】

The coating method for castings according to the present invention involves coating the castings by dipping them in a heated state, so that the paint dries quickly, and even if the castings have recesses, the paint inside the recesses will dry. This also improves efficiency significantly, and prevents paint from dripping or scattering during movement or transportation of castings. Further, the heating of the casting can be done economically since the residual heat from the manufacturing of the casting or the residual heat from the heat treatment can be used.

Claims (2)

[Claims] (1) A method for coating a cast product, which is characterized by dip-coating a heated cast product. (2) The method for coating a cast product according to claim 1, wherein the heating is performed using residual heat during production of the cast product or residual heat during heat treatment of the cast product.