JPS5927263B2 - Precision casting pattern manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a pattern for precision casting, and more specifically, to a method for manufacturing a pattern by assembling divided members and adhering them to each other.

When manufacturing patterns for precision casting, it is difficult to mold them in one piece.
- It is necessary to obtain a pattern in the shape of a cast product by gluing separately molded members together at the parting surfaces of the pattern.

Therefore, an application method has been used in which each member is held together at the adhesive surface, left at a temperature of 100° C., and then the adhesive is applied to the adhesive surface with a brush.

Since the material of the pattern is most often wax, adhesives made of the same material as the pattern, such as paraffin wax, have been most widely used.

However, according to this method, there was a phenomenon in which the adhesive 2 protruded from the adhesive surface as shown in FIG.

Furthermore, in the case of a thin pattern, there was a phenomenon in which the thickness of the bonded portion became non-uniform.

These phenomena had a high tendency to lead to deterioration of pattern properties.

In addition, when looking at the conventional manufacturing method from the perspective of ease of manufacturing patterns, especially when manufacturing a pattern with a thin wall and a wide adhesive surface, it takes time to apply the coating to the adhesive surface, resulting in poor workability. It was extremely bad.

For this reason, in the case of a thin material, there was a high risk that the pattern would be deformed during the coating process.

Furthermore, conventional manufacturing methods were not suitable for mass production of patterns.

The present invention aims to provide a method to overcome these drawbacks.

The method according to the present invention is a method for manufacturing a precision casting pattern by integrating pattern members that have been molded separately by adhesion, and holds the pattern member made of urea resin with its surfaces to be bonded together. In addition, the pattern member is immersed in a paraffin bath while maintaining a state in which paraffin permeates between the mating surfaces.

In the present invention, a urea resin pattern material generally referred to as ureamics is used.

As the urea-based resin, resin materials that are mainly composed of addition products, condensation products, and co-condensation products of urea and epoxy from the reaction between urea and formalin, and in which fillers and the like are added are used.

However, it is possible to use various resin materials that use urea as a starting material and have the characteristics of a urea resin and the properties required for the pattern, such as hardness, low shrinkage, expansion coefficients, etc.

In addition, the paraffin used as the adhesive material in the present invention at ℃ 8 is solid at room temperature and has a melting point of 50 ℃ 8.
The material at 0°C has the following properties required as an adhesive.

That is, (1) it does not dissolve the pattern material, i.e., urea resin, (2) it has a low ash content, (3) it has a viscosity that allows for uniform adhesion or sealing, (4) Paraffin that meets the above requirements satisfies the following requirements: 1) quick drying, and 5) easy handling and safety.

The present invention was tested by immersing a urea resin pattern in a bath of adhesive other than paraffin, but when the surface quality of the pattern deteriorated, there was a problem due to the wettability of the adhesive to the pattern. It was discovered that a paraffin bath is most suitable for urea resin pattern materials.

In the method according to the present invention, the pattern member is held together on the surface to be bonded by using an adhesive locally or using a jig to fix the pattern member. This condition is maintained during immersion in the paraffin bath.

FIG. 2 shows the state of the pattern adhered by the method according to the invention.

The plates 1 are glued together by an adhesive 2, which penetrates and adheres between opposite surfaces of the plates, thereby increasing the wall thickness uniformly.

The pattern thickness increase is influenced by the paraffin bath temperature and immersion time.

That is, if the temperature of the paraffin bath is too low, the thickness of the pattern will be non-uniform and air bubbles will adhere to the pattern.

In addition, the melting point of Yuryamicus is 120 to 130°C, and Yuryamicus is not made of wax.
Even if it is closed, it is sensitive to heat and deforms, so if the temperature of the paraffin bath becomes high or the immersion time is too long, the pattern will deform and become unusable.

Therefore, the temperature of the paraffin bath is between 90°C and 110°C.
The appropriate immersion time is 3±1 seconds.

The pattern produced by the method according to the present invention is characterized by the fact that the bonding position cannot be determined (the wall thickness increases uniformly at the bonding point at °C).

An example of a preferable pattern that utilizes such characteristics is a thin-walled pipe that is a combination of divided patterns.

When making thin-walled pipes using conventional manufacturing methods, the wall thickness at the joints becomes so thick that the bonding position can be determined at a glance.

Bulging at joints on the outside of the pipe can be corrected by running a grinder over the product.

However, although the bulges at the joints on the inner surface can be corrected when the pipe is short, it is difficult to correct it when the pipe is long.

However, with the method of the invention no modification of the bonding location is necessary.

A preferred example of the pattern produced according to the present invention is a pattern with a complicated shape, for example, a pattern in which several round rods are erected on the surface of a flat plate.

When such patterns are manufactured using conventional manufacturing methods, the adhesive often protrudes from the bonded surface or requires further sealing after bonding.

In such cases, the shape of the pattern is complicated, making it difficult to correct or line the pattern.

However, according to the present invention, bonding and sealing can be carried out in a few seconds, and at the same time, the corners are provided with an R of about .degree.

A cast product manufactured using a pattern assembled by this method is just like a product made using an integral pattern.

In addition, when carrying out the present invention, it is necessary to make the divided patterns small in anticipation of an increase in wall thickness when the patterns are bonded.

Also, the degree of increase in wall thickness can be changed by changing the bath temperature and immersion time.

Hereinafter, the present invention will be explained in detail based on Examples.

In all Examples, the pattern material was urea resin, and paraffin had a melting point of around 65°C.

Example 1 A test was conducted in which 14 sets of two plates each having a length and a width of 40 mm were bonded together.

The thickness of the plates ranged from 0.5 mm to 2.7 mm for each set.

Two parts of the board were sandwiched together to fix the adhesive part of the board, and the sheet metal body was immersed in a paraffin bath.

The temperature of the paraffin bath and the immersion time were varied as shown in Table 1.

Tests were conducted using five test materials under each experimental condition.

The results are shown in Table 1. The results of immersion time of 3 seconds in Table 1 are as follows:
Pattern thickness increase (
Fig. 3 shows the relationship between the vertical axis and the vertical axis.

The range in which the pattern properties were good is indicated by diagonal lines as the optimum temperature range.

Example 2 In producing a pipe-shaped pattern, first, a two-part pattern 1 a t i b as shown in FIG. 4 was produced.

The plate thickness is 1.0 to 1.5 mm. Division pattern 1a,
In order to position 1b on the adhesive surface, insets 3a and 3b are provided in the seed portions of the divided pattern.

The divided putters were held together as shown in FIG. 5, and immersed in a paraffin bath at 110° C. for 3 seconds while maintaining this alignment.

After gluing and assembling the integrated pattern into a tree, a mold was made, and 5C8I8 material was poured into the mold.

In manufacturing this pipe-shaped pattern, since the thickness of the pattern was uniform, there was no need to modify the pattern after bonding.

The castings also had surface textures similar to those produced with a monolithic pattern.

Example 3 The plan view is shown in Fig. 6, and the front view is shown in Fig. 7.
In order to produce cast products like this, patterns were created by combining round bars and flat plates.

The round rod and flat plate were fixed using adhesive so that they would not break even if they were tilted when immersed in a paraffin bath.

At this stage, only a small amount of adhesive was applied to the center of the round bar.

Thereafter, the whole was immersed in a paraffin bath at 105° C. for 4 seconds to completely integrate it.

After that, a mold was made and 5C8I8 was poured into the product.

When producing the pattern in this example, adhesion and stitching were performed at the same time, and the corners where the round bar and the flat plate were in contact were rounded.

The bonded pattern could be used for mold making without any modification.

As can be seen from the above description, according to the manufacturing method of the present invention, it is possible to complete in just a few seconds the integration of divided patterns, which conventionally took a considerable amount of time.

Also, the operator does not need to be highly skilled. In addition, since the effects described in detail in the Examples are achieved, the present invention is extremely useful in manufacturing patterns for precision casting.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a pattern made by the conventional manufacturing method, Figure 2 is a cross-sectional view of a pattern made by the manufacturing method of the present invention, and Figure 3 is the relationship between paraffin bath temperature and pattern thickness increase. FIG. 4 is a perspective view of the divided pattern, FIG. 5 is a perspective view of the integrated pattern of FIG. 4,
FIG. 6 is a plan view of a specific example of the pattern, and FIG. 7 is a front view of the pattern shown in FIG. 1-pattern member, 2-adhesive layer.

Claims (1)

[Claims] 1. A method for manufacturing a pattern for precision casting by integrating pattern members that have been molded separately by adhesion, comprising: aligning and holding the pattern member made of urea resin with its surfaces to be bonded at ℃°C; A method for manufacturing a pattern for precision casting, characterized in that the pattern member is immersed in a paraffin bath while maintaining a state in which paraffin permeates between mating surfaces.