JPH01181945A - Core for casting - Google Patents

Abstract

PURPOSE:To drastically reduce the deteriorating ratio of a product and to surely remove sands in a product for short time by using salt or sand as main material and adding the specific concn. of CaC2 to this. CONSTITUTION:After adding 1-10wt.% CaC2 to salt core sand core using the salt or the sand as the main material the pressurization and heating-formation are executed. When the added quantity of CaC2 is a little, as generated quality of C2H2 with action of water is a little, collapsiblity of the core is poor, and when the CaC2 is so much, as contacting action with moisture in the air is executed, the prevention of moisture absorption in the core is difficult. When product taking out from the metallic mold is dipped into the water or the water is sprayed, the core in the product is rapidly collapsed and removed with C2H2 from CaC2 generating by contacting action with the water. Further, by adding phenol resin as binder combining salt grain at the prescribed quantity, the pressurization and heating-formation may be executed. By this method, the sands, etc., from the product can be surely removed and the removing work of the core can be drastically improved.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a casting core used in a mold casting method such as a gravity casting method, a low pressure casting method, or a die casting method. Pressurized with salt or sand as the main material so that it can be easily disintegrated and removed.

The present invention relates to a salt core or a sand core that is heat-formed and is mainly used as a placing core that is assembled and set in a mold when casting molten metal such as A1 alloy or zTI alloy.

<Conventional technology and its problems> Conventionally, this type of salt core or sand core for casting has high strength and heat resistance so that there is no risk of it collapsing due to the injection pressure of the molten metal applied when pouring the molten metal or its thermal shock. Various types of cores have been developed to meet these conditions so that they can be easily disintegrated and removed from the product after casting, but all of the cores have poor disintegration properties and require time and effort to remove the core after casting. Not only did it cost more, but it also caused a huge amount of waste.

For example, when removing a salt core from a product cast using a salt core, there is a method of spraying high-pressure water at a constant pressure onto the core to dissolve the core. When the core is removed using high-pressure water, there is a tendency for the core to not be completely eluted and a portion of it remains in the product.As a result, the remaining core increases the defective rate of the product and leads to waste. 17570
(see publication).

On the other hand, in the case of sand cores, unlike salt cores, they do not dissolve even when sprayed with water, so the product is made by thermally decomposing, for example, phenol resin, which is added at the time of molding as a binder to bind sand grains, by heating at high temperatures. It is common to use a method of removing from the inside, but in reality, this method of removal is about 45
Since phenolic resin cannot be thermally decomposed unless it is heated at a high temperature of 0℃ for a long time of 3 to 4 hours, equipment such as a heating furnace that can maintain a high temperature of about 450℃ is required. As a result, the product is also heated, causing swelling and cracking in the product due to the heat effect, often resulting in a defective product, and furthermore requiring fuel costs and labor (man-hours).

<Problem to be Solved by the Invention> The technical problem to be solved by the present invention is that after casting, the product can be immersed in water such as a water tank or sprayed with tap water. It is an object of the present invention to provide a casting core that can be disintegrated and removed reliably and in a short period of time.

Means for Achieving the Technical Problem> The technical means taken by the present invention to achieve the above object is to use salt or sand as the main material, and to add Ca in weight percent.
The method is to add 1 to 10% of Cz, pressurize and heat mold.

According to the above-mentioned technical means of the present invention, when the product taken out from the mold after casting is immersed in water or sprayed with water, the core in the product becomes immersed in water. It is rapidly disintegrated by C2H2 from CaC2 generated by the contact action of CaC2, and is removed from the product.

<Example> The present invention will be explained in detail. In the present invention, it is necessary to suppress the amount of Ca Cz added within 1 to 10% by weight.

The reason for this is that if it is less than 1%, the amount of C2H2 generated by the interaction with water or hot water is too small, resulting in poor core disintegration and disintegration, and if it is more than 10%, the contact effect with moisture in the atmosphere There is a risk that This is because it becomes difficult to prevent the so-called hygroscopicity of the core.

Therefore, C is added to the salt core or sand core whose main material is salt or sand.
a C; 2 is added in an amount of 1 to 10% by weight, and the mixture is pressurized and heated.

In addition, when molding the casting core of the present invention, for example, when making a salt core with a diameter of 25 mm and a thickness of 10 nm, the weight is approximately 400 kg/c.
The material is press-molded at a pressure of i, and heated at a heating temperature of about 200° C. for a certain period of time. It is also possible to add 1 to 5% by weight of phenolic resin as a binder to bind the salt grains to the salt, which is the main material when forming the salt core, and then pressurize and heat mold it. The phenolic resin is added as an organic powder.

Next, using the salt cores made under the above-mentioned molding conditions, a disintegration test was conducted with respect to the amount of Ca C2 added, and the results are shown in FIG.

As is clear from the table shown in FIG. 1, the salt core of the present invention has Ca
It was confirmed that when the amount of C2 added was 7%, it disintegrated in a short time of about 2 minutes. Note that these experimental results were obtained by immersing the salt core in water (cold water); if the core were immersed in hot water or sprayed with high-pressure water, the time it would take for the core to disintegrate would be much shorter. It is something that becomes.

<Effects of the Invention> As mentioned above, the casting core of the present invention is made of salt or sand as the main material and 1 to 10% by weight of CaCz is added thereto, so that it cannot be immersed in water or When water is sprayed on it, it is rapidly destroyed by 02 H2 generated from Ca C2 due to the action with water. Therefore, there is no need for a part of the core to remain in the product or to heat it as in the past, so the defective rate of the product can be significantly reduced and it can be removed reliably and quickly from the product. Moreover, the core removal work was greatly improved, and a highly practical casting core could be provided.

Therefore, the intended purpose was achieved.

Claims (1)

[Claims] The main material is salt or sand, plus CaC in weight percent.
A casting core characterized by containing _21 to 10% of the additive.