JPS591905B2 - Manufacturing method of graphite gasket - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a graphite gasket material having portions of different densities in the same product.

An internal combustion engine is composed of main structures such as a cylinder head, a cylinder block, and an oil pan, and a cylinder rad gasket is used as a sealing material for the cylinder head and cylinder block.

Conventional cylinder head gaskets are equipped with thin metal plates called grommets in a circular shape around each hole to prevent leakage of high-pressure combustion gas in the combustion chamber, as well as leakage from oil and water holes. leakage was prevented by applying high surface pressure.

However, during actual use, a sliding phenomenon occurs on the surface of the gasket material due to a difference in thermal expansion between the cylinder head and the cylinder block.

Gasket materials with metal grommets have the disadvantage that the surface pressure on the grommet is high, so slippage occurs here, and a large shearing force is applied, causing abnormal phenomena such as cracks and chips, which can lead to gas leaks. There is.

The purpose of the present invention is to provide a highly productive method for forming the areas around the combustion chamber, water holes, and sleeve holes by using graphite gasket material with excellent compression and recovery properties except for the reinforcing core material without using metal grommets. The graphite gasket material is engineered to have high density and high surface pressure during tightening to prevent leakage and has extremely good performance without sliding problems due to thermal expansion differences. It lies in providing well.

The present invention is characterized in that the portions of the metal reinforcing plate having wire mesh or protrusions that require high surface pressure are filled with a larger amount of gasket material than other portions, and furthermore, the wire mesh or protrusions are placed approximately in the center of the thickness of the gasket material. The present invention relates to a method for producing a graphite gasket material in which a metal reinforcing plate having the following properties is installed and then integrally molded under pressure to provide a partial density difference.

In the present invention, the portions of the metal reinforcing plate having wire mesh or protrusions that require high surface pressure are around the combustion chamber, water holes, armholes, etc.

As the gasket material in the present invention, graphite with a highly developed crystal structure such as natural graphite, quiche graphite, and pyrolytic graphite is mixed with a strongly oxidizing solution such as a mixture of concentrated sulfuric acid and nitric acid, or a mixture of concentrated sulfuric acid and potassium permanganate. Graphite particles are used that are in a green form and have compressive recovery properties, which are obtained by acid treatment with a treatment solution to generate a graphite intercalation compound, washing with water, rapid heating, and expansion treatment in the direction of the C-axis force of the graphite crystal.

The details of the present invention will be explained below with reference to the drawings.

Prepare a mold with steps as shown in Figure 1 in order to create a density difference between areas such as the combustion chamber, water holes, and oil fill areas that require high surface pressure, that is, high density, and areas where low density is sufficient. do.

It's just ugly. This step can be adjusted variably using spring 6 until it disappears.

Next, a predetermined amount of graphite particles 1 are put into this mold.

In this case, the amount of filling in areas that need to be high density will be larger than in areas with low density due to the effect of the level difference.

Next, a reinforcing plate 2 made of metal having protrusions on both sides is installed, and a predetermined amount of graphite particles 3 are placed on its upper surface.

Next, as shown in FIG. 2, by pressurizing and integrally molding until there are no steps, a partially dense graphite gasket shown in FIG. 3 is obtained.

In addition, in the present invention, the graphite particles 1 on the top and bottom of the metal reinforcing plate 2
and 3 are tablets with different densities made using a water mold in advance) [The graphite gasket is then fabricated by pressurizing and integrally molding both sides of the tablet through a metal reinforcing plate having a wire mesh or protrusions in the center. You may do so, and there are no particular restrictions.

The density difference between the high-density portion 4 and the low-density portion 5 can be freely changed by setting the step.

Generally, a density difference of 1.1 to 2.0 times the phase degree is preferred.

When the molded body thus obtained is installed in an internal combustion engine and tightened to a specified torque, the high-density part will have a higher surface pressure than the low-density part, making it possible to seal out high-pressure gas, oil, and water during combustion. Since the surface of the sliding part is made entirely of graphite, there is little sliding resistance, and there are no defects such as cracking or chipping that occur in metal grommets, and the gasket exhibits good performance.

Furthermore, since materials for the combustion chamber, sleeve holes, and water holes are not required, there is an advantage that a large amount of material can be saved.

The present invention will be explained in detail below.

Example 1 100 g of natural scaly graphite from the Soviet Union having a fixed carbon content of 97 mm and a peak of 48 mesh was treated in a mixed acid of 300 g of 95% sulfuric acid and 100 g of 62 mm nitric acid for 2 hours, and then washed with water. The graphite particles (expanded graphite) having compression recovery properties were obtained by heating and expanding the particles in a furnace of about 8,000 liters for 2 minutes.

Next, a mold for a gasket for a gasoline engine as shown in FIG. 1 having a combustion chamber with a diameter of 50 mm (ψ gauze) was made.

In addition, in this mold, a step of 1711 Lm was provided in a part of the combustion chamber with an outer diameter of 60 mm ψ and an inner diameter of 50 - ψ to achieve high density.

First, a certain amount of the graphite particles 1 obtained above are uniformly charged into the mold.

Next, SPC steel plates with a thickness of 0.2 mrn were cut into diameters of 1 mm at intervals of 2.5 mm. Metal reinforcing plate 2 with split holes (OmQψ) drilled alternately on the top and bottom so that the height of the claws is approximately 1.8 mm/L.
Insert.

Furthermore, a certain amount of graphite particles 3 are uniformly added to the top surface.
Pressure molding is carried out using the method shown in Fig. 2 so that the plate thickness becomes 1.5 mm under a surface pressure of 50 kg/cm2.

The thus obtained graphite gasket has a density of 1.77 g/C1113 in the high density part 4 and 1.38' in the low density part 5.
/cfrL3, and when tightening this graphite gasket, if the overall thickness is in the order of 1.4, the contact pressure of the high density part is 350kg/cIn2, and the contact pressure of the low density part is 120kgZ
It has been confirmed through experimental support that the σ attack occurs.

In addition, when this graphite gasket is installed on an actual engine, the load is 4/
When a 100-hour durability test was conducted on No. 4, it showed good gasket performance with no leakage.

According to the present invention, there is a sleeve hole for leaking high pressure combustion gas in the combustion chamber.
It is possible to obtain a graphite gasket material with high productivity, which prevents leakage from water holes and has extremely good performance without sliding problems due to differences in thermal expansion.

[Brief explanation of drawings]

1 and 2 are schematic diagrams showing the method for manufacturing a graphite gasket according to the present invention, in which FIG. 1 is a sectional view showing the state before molding, FIG. 2 is a sectional view showing the state after molding, FIG. 3 is a plan view of the graphite gasket according to the present invention. Explanation of symbols 1...Graphite particles, 2...
Metal reinforcing plate, 3...Graphite particles, 4...
・High density part, 5...Low density part, 6...
Spring.

Claims (1)

[Claims] 1 Fill the part of the metal reinforcing plate with a wire mesh or protrusions that requires a high surface l+ with a larger amount of gasket material than other parts, and furthermore, fill the metal reinforcing plate with a wire mesh or protrusions approximately in the center of the thickness direction of the gasket material. A method for producing a graphite gasket material, which is characterized by installing a reinforcing plate made of carbon dioxide, and then integrally molding it under pressure to create a partial density difference.