JP2693548B2 - Cold box mold manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to an improvement in a method for manufacturing a cold box mold.

(Prior Art) Conventionally, a hot box method such as a shell mold method has been generally used as a method for molding a mold. In this hot box method, casting sand is blown into a preheated mold. Since it is a method of molding a mold by heating and curing with, there is a pollution problem that it requires fuel for heating and produces a bad odor during heating and curing, so recently as an alternative method The cold box method is being adopted.

However, the mold produced by the cold box method has drawbacks in that it has smaller bond strength and is more brittle than the mold produced by the hot box method.

Therefore, for example, as disclosed in JP-A-60-124436, as a method for producing a molding sand for a cold box capable of increasing the strength of a mold, a silane coupling agent is mixed with refractory particles such as silica sand. A method has been proposed in which a binder such as a resin is added and kneaded to the kneaded product after kneading.

(Problems to be solved by the invention) However, in the molding sand obtained by the method of the above-mentioned proposal example, since the mixing amount of the silane coupling agent is extremely small, the silane coupling agent is uniformly distributed in the refractory particles. It is difficult to distribute, and therefore, the function of the silane coupling agent is not sufficiently exerted to the entire refractory particles, and the strength of the mold has not yet been increased to the desired strength.

The present invention has been made in view of such a point, and its purpose is to disperse the silane coupling agent in the refractory particles by appropriately mixing the silane coupling agent in the refractory particles. It is intended to improve the adhesiveness of the refractory particles and the binder so that the strength of the cold box mold is surely increased.

(Means for Solving the Problem) In order to achieve the above object, the means for solving the problems of the present invention is to first mix and knead a refractory particle such as silica sand with a silane coupling agent and a nonpolar solvent. Next, a binder such as a resin is added to this kneaded product and kneaded to obtain a molding sand. After that, a cold box mold is formed using this mold sand.

(Operation) With the above-mentioned configuration, in the method of the present invention, since the silane coupling agent is mixed with the non-polar solvent in the refractory particles such as silica sand and kneaded, the silane coupling agent is non-polar during the kneading. The solvent is used as a medium to quickly and uniformly disperse the refractory particles, whereby the function of the silane coupling agent is sufficiently exerted on the refractory particles as a whole. Adhesion between the material particles and the binder is improved. Therefore, the strength of the cold box mold produced using the foundry sand composition in which the adhesion between the refractory particles and the binder is improved can be surely increased.

(Example) Hereinafter, a method for manufacturing a cold box mold according to an example of the present invention will be described.

First, a mixture of a silane coupling agent and a nonpolar solvent is mixed with refractory particles such as silica sand and kneaded for 2 minutes, for example. Examples of the silane coupling agent used here include N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane (CKBM602 manufactured by Shin-Etsu Chemical Co., Ltd.), γ-
Aminopropyltriethoxysilane (KBE902 manufactured by Shin-Etsu Chemical Co., Ltd.) and N-β (aminoethyl) γ-aminopropyltrimethoxysilane (KBM603 Shin-Etsu Chemical Co., Ltd.)
Manufactured) and the like. Further, the mixing amount of the silane coupling agent is preferably set to be in the range of 0.0005 to 0.003 wt% with respect to the refractory particles. That is, as is clear from the data showing the relationship between the mixing amount of the silane coupling agent and the compressive strength of the mold immediately after molding shown in FIG. 1, the mixing amount of the silane coupling agent was less than 0.0005 wt% or 0.005 wt%.
If it exceeds 3 wt%, the compressive strength of the mold immediately after molding will be 30 kg / cm.
It is smaller than ² and smaller. In obtaining this data, the mixing amount of the binder to be described later with respect to the refractory particles was 2 wt%, and the mixing amount of kerosene as the nonpolar solvent was 0.2%.
set to wt% respectively.

The non-polar solvent is used to prevent the reaction with the silane coupling agent, and examples thereof include kerosene, spindle oil and C heavy oil. Also,
The amount of the mixture is preferably set to be in the range of 0.1 to 0.4 wt% with respect to the refractory particles. That is, as is clear from the data showing the relationship between the mixing amount of kerosene and the compression strength of the mold immediately after molding shown in Table 1 below, when the mixing amount of kerosene is less than 0.1 wt% or exceeds 0.4 wt%, This is because the compressive strength immediately after molding of the mold becomes small. When obtaining this data, the amount of silane coupling agent (CKBM602) mixed with refractory particles (Yayoi silica sand) was set to 0.0.
The mixing amount of 01 wt% and the binder was set to 2.0 wt%.

Incidentally, the amount of silane coupling agent (CKBM602) mixed with refractory particles is 0.001 wt% and the amount of binder is 2.
The compressive strength of the mold immediately after molding when set to 0 wt% and the nonpolar solvent mixture amount of 0.3 wt% are 28.8% respectively when the nonpolar solvent is kerosene and spindle oil.
kg / cm ^2, in the case of C heavy oil was the 27.7kg / cm ^2,
In the above cases, it was as small as 23.9 kg / cm ² when the non-polar solvent was not mixed, and as small as 20.7 kg / cm ² when both the non-polar solvent and the silane coupling agent were not mixed. It was This also indicates that the non-polar solvent and the silane coupling agent have a considerable influence on the compression strength of the mold immediately after molding.

Next, after leaving the kneaded product for 15 minutes, for example, a binder such as a resin is added to the kneaded product and kneaded for 2 minutes to obtain molding sand. The binder used here is composed of, for example, a phenol resin and a curing agent such as polyisocyanate.

After that, the molding sand is filled in a molding die, and then an amine gas is passed through the molding die for 10 seconds to mold the cold box mold.

Then, the amine gas in the molding die is removed by an air purging step, and the molded cold box mold is taken out of the molding die.

As described above, in this embodiment, since the mixture of the silane coupling agent and the nonpolar solvent is mixed with the refractory particles such as silica sand and kneaded, the silane coupling agent is mixed with the nonpolar solvent during the kneading. As rapidly dispersed uniformly in the refractory particles as, by which the function of the silane coupling agent can be sufficiently exerted with respect to the entire refractory particles, during the subsequent addition of the binder, with the refractory particles and The adhesiveness with the binder can be structured. Therefore, by using this molding sand, it is possible to surely increase the strength of the cold box mold.

In order to prove this, the relationship between the mixing amount of the binder and the compressive strength of the mold immediately after molding was examined in the case of this example and the case of the comparative example. As a result, as shown in Table 2 below,
In order to obtain the same compressive strength, this example can reduce the amount of the binder mixed by about 10 wt% as compared with the comparative example, which means that the refractory particles and the binder are mixed with each other. Shows that the adhesiveness of the mold is improved, that is, the strength of the mold can be increased. In the comparative example, molding sand made of only refractory particles mixed with a binder was used without using a silane coupling agent or a nonpolar solvent.

In the above examples, the mixture of the silane coupling agent and the nonpolar solvent was mixed with the refractory particles such as silica sand and kneaded, but not limited to this, for example, refractory particles,
It is also possible to employ a method in which a silane coupling agent and a non-polar solvent are mixed and kneaded at the same time, and even in this case, the same operational effect as in the above-mentioned embodiment can be obtained.

(Effects of the Invention) As described above, according to the method of the present invention, the silane coupling agent is not mixed with the refractory particles such as silica sand by mixing and kneading the silane coupling agent and the nonpolar solvent. Since it is intended to quickly and uniformly disperse in the refractory particles via a polar solvent, by adding and kneading the binder thereafter, the foundry sand with improved adhesion between the binder and the refractory particles. Therefore, when a mold for a cold box is formed by using this foundry sand, it is possible to surely increase the strength thereof.

[Brief description of the drawings]

FIG. 1 is a diagram showing data showing the relationship between the compressive strength immediately after molding of a cold box mold molded by the method of the present invention and the mixing amount of a silane coupling agent.

Claims (1)

(57) [Claims] 1. A refractory particle such as silica sand is mixed and kneaded with a silane coupling agent and a non-polar solvent, and then a binder such as a resin is added and kneaded to the kneaded product to obtain a foundry sand. Then, a method for producing a cold box mold is characterized in that a cold box mold is formed using this foundry sand.