JPS5844447B2 - Compression mold for flexible graphite particles - Google Patents

Description

[Detailed description of the invention] The present invention relates to a compression mold for flexible graphite particles.

More specifically, the present invention relates to a compression molding mold for flexible graphite particles that can make the bulk density of flexible graphite particles filled into the mold uniform.

Conventionally, lightweight caterpillar-shaped flexible graphite particles (hereinafter referred to as It is known that graphite particles (often referred to simply as graphite particles) have excellent compression moldability and can easily be formed into sheet-like or block-like molded products when pressed alone or mixed with a binder.

Moreover, these graphite molded bodies have excellent heat resistance, chemical resistance, and lubricity, and are widely used as gaskets and backings in various mechanical devices, automobiles, and the like.

However, in general, graphite particles have a bulk density Q, Qig/cc
They are lightweight particles, and they become lumpy even under a slight pressure of several 9/crit or less, making it difficult to fill them with material during molding, which tends to result in non-uniform molded products.

Furthermore, since it is easily compressed, a considerably deep mold is required when molding thick-walled products, which has the disadvantage of causing restrictions in processing and increasing mold production costs.

Therefore, the present inventors first developed graphite particles with a compression ratio of 1.0 to
After being conveyed and press-fitted into a mold attached to the tip of the extruder by an extrusion molding machine equipped with a 3.5 screw,
We proposed a method to easily form thick molded products by recompressing the graphite particles filled in the mold.

← Japanese Patent Publication No. 56-42613). However, this method δ
Even in this case, there is a disadvantage that the graphite particles filled into the mold still have a small bulk density and contain a large amount of air.

For this reason, the graphite particles that are conveyed and press-fitted into the mold by the screw are well-transmitted to the part near the filling port from the screw, which compresses the graphite particles well and increases the bulk density. Because pressure transmission from the screw is insufficient in this area, the bulk density is smaller than in the area near the filling port.

As a result, even in the molded body obtained by recompressing the filled graphite particles, the problem of nonuniform physical properties remained unsolved.

Furthermore, a considerable amount of air is contained in the area away from the filling port from the screw, and this air cannot escape during compression molding, so it may remain inside the molded object and cause peeling phenomenon. In areas close to the compression molding process, the graphite particles are crushed and compressed by the pressure of the screw before the compression molding process, and the compression moldability, which is a feature of flexible graphite particles, is lost before the compression molding process. The disadvantage was that the strength was weakened.

Furthermore, if air remained in the mold, slippage would occur at the tip of the screw when filling a certain amount of graphite particles into the mold, resulting in a time-consuming filling process and poor production efficiency.

The inventors of the present invention have conducted intensive research into an economical molding die that has uniform physical properties and is capable of producing a graphite molded body without blistering or peeling due to residual air, and has a short mold length. This invention has been achieved.

Therefore, one object of the present invention is to uniformly increase the bulk density of flexible graphite particles filled in a mold while maintaining compression moldability of the flexible graphite particles before being compressed. Accordingly, it is an object of the present invention to provide a mold for molding flexible graphite particles, which can efficiently produce a molded article having uniform physical properties.

Another object of the present invention is to provide an economical compression molding mold having a short mold length for compression molding flexible graphite particles.

According to the present invention, a molding die for compression molding flexible graphite particles is passed through a molding die, and a mold is placed on the wall portion of the mold corresponding to a portion of the inner wall surface of the mold that is not in contact with a molded article after compression molding. A mold for compression molding flexible graphite particles is provided, the mold being characterized by having at least one hole communicating between the inside and outside of the mold.

Next, the configuration of one embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is an overall view of a flexible graphite particle forming apparatus.

1 is a hopper, 2 is a vertical screw extruder, 3 is a press cylinder, 4 is a take-out cylinder, 5 is a fixed plate, 6 is a rotary plate, 7 is a molding die of the present invention, 8 is a lower punch cylinder, 9 is a support column, 10 is a rotating disk drive motor.

The molding die 7 is provided with at least one hole that communicates the inside and outside of the mold in a wall portion of the mold corresponding to a portion of the inner wall surface that does not come into contact with the molded product after compression molding. be.

FIG. 2 is a sectional view showing an example of an embodiment of the present invention,
A state in which flexible graphite particles 14 are filled from a vertical screw extruder 2 into a mold 7 of the present invention is shown.

11 is a screw, 12 is a cylinder, and 13 is a hole.

The holes 13 provided in the molding die 7 allow the filling ((
The flexible graphite particles are deaerated, the bulk density of the flexible graphite particles is uniformly increased, and air is prevented from remaining in the graphite molded body.

Furthermore, as a result of the holes, no slip occurs during filling, improving filling efficiency.

Although a vertical screw extruder is shown in FIGS. 1 and 2, a horizontal screw extruder may also be used, and the molding die of the present invention can be used regardless of the type of the screw extruder.

Further, in the present invention, the bulk density of the raw material is 0. OL! i'
/(Flexible expanded graphite particles of A or less are immersed in a liquid, stirred until the graphite particles are compressed and increased in density and simultaneously become granules, separated from the liquid, and the resulting product is dried. The obtained graphite granules are preferably used.

In the present invention, graphite particles and graphite granules are similarly referred to as flexible graphite particles.

FIG. 3 is a diagram showing a state in which the flexible graphite particles filled as shown in FIG. 2 are compression-molded.

15 is a compression molded graphite molded body.

The diameter of the pores varies depending on the particle size of the graphite particles or graphite granules used, but is generally 0.5 mm or more and 3 mm or less, preferably 1 mm or more and 2 mm or less.

However, the shape of the hole is not limited and may be circular or any other shape.

Further, the hole does not have to pass straight through the outside and inside of the mold, but may be a meandering hole.

[Brief explanation of the drawing]

Figure 1 is an overall view of the flexible graphite particle molding device, Figure 2 is a sectional view of the main part showing the state in which flexible graphite particles are being supplied to the molding die, and Figure 3 is a diagram of the flexible graphite particle forming device. FIG. 2 is a cross-sectional view of a compression molding mold showing a state in which particles are compression molded. 7...Compression mold, 13...Li2
...Flexible graphite particles, 15... Compression molded graphite molded body.

Claims (1)

[Claims] 1. A molding mold for compression molding flexible graphite particles, and a wall portion of the mold corresponding to a portion of the inner wall surface of the mold that does not contact the molded product after compression molding, is provided with a mold inside and outside the mold. A mold for compression molding flexible graphite particles, characterized in that the mold is provided with at least one hole communicating with the two.