JPS5825916A - Continuous molding method for graphite shape - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of stacking a plurality of flexible graphite sheets (hereinafter simply referred to as sheets), pressing them together and molding them. More specifically, the present invention relates to a method of supplying an appropriate number of sheets between a pair of upper and lower forming rolls and continuously pressing them together to form a graphite molded body.

Graphite has excellent heat resistance, chemical resistance, and lubricity, and its sheet-like products are used as gaskets in various mechanical devices, automobiles, etc.
It is widely used in practical applications such as Nosotsuking. However, due to its excellent physical properties, there is a strong demand for gutter-shaped or other irregularly shaped products, and there has been a desire from various fields for the development of a molding method that would make this possible.

Conventionally, when trying to obtain a gutter-like shape like a cylinder split vertically from a sheet of graphite, when a single sheet was deformed under pressure, the plasticity was extremely small due to the graphite's crystal structure, resulting in cracks and cracks.・It is known that wrinkles etc. may occur. For example, a sheet with a density of 1.0 g/cm3 and a wall thickness of 0.5 mm will wrinkle when bent into a curved surface with a radius of curvature of 10 mm or less, and a sheet with a wall thickness of 1.5 mm will wrinkle when bent into a curved surface with a radius of curvature of 50 mm or less. If it is bent, it will wrinkle, and if the radius of curvature is less than 30 degrees, it will break. Similarly, as can be easily inferred from its crystal structure, a graphite sheet has a small degree of stress relaxation, and it is impossible to maintain the desired shape when an external force is removed.

Therefore, instead of pressing and molding a single relatively thick graphite sheet, a method may be considered in which a suitable number of relatively thin graphite sheets are piled up and pressure molded.

In other words, by crimping and molding multiple graphite sheets into one piece, it is possible to avoid wrinkles or cracks, and to maintain the desired shape even when external forces are removed due to the adhesion between the sheets. be.

However, when pressure forming multiple graphite sheets using the conventionally known mold press method, air remains between the sheets because the gas permeability of the graphite sheets is extremely low.
It comes as a blister.

In addition, in this case, the structure of graphite is a layered lattice made up of layers of connected inner carbon rings, so
Since the sheets are not crimped and integrated at all corresponding points, stress remains in the molded body. This stress is not relieved, and therefore, after being removed from the mold, it cannot maintain the same shape as the mold. Alternatively, in severe cases, the sheets may peel off from each other. Furthermore, in such a molding method, in order to obtain a molded product with a density of about 1.8 fl/cm3, a pressure of 800 to 1 OOO kg/cm2 is required depending on the shape of at least 40 Okti/cmz%, so an extremely large press is required. This requires a machine and is expensive.

Furthermore, there is a major drawback in terms of labor and time, since graphite sheets must be supplied each time the molding is performed.

The inventors of the present invention conducted extensive research to eliminate these drawbacks, and as a result, they arrived at the present invention, which enables molded products that do not bulge due to residual air or have residual stress when multiple sheets are stacked, crimped, and molded into one piece. The goal is to provide a way to obtain

Another object of the present invention is to provide the above-mentioned method which is economical and suitable for mass production of target products.

These and other features and benefits will become apparent from the following detailed description, taken in conjunction with the accompanying drawings.

According to the present invention, a graphite sheet stack consisting of a plurality of flexible graphite sheets is formed by a pair of upper and lower forming rolls each having a roll surface of a predetermined shape, and the crimping width of the stack is increased in stages. The crimping rolls are continuously introduced between the crimping rolls with the smallest crimping width of the plurality of crimping roll groups, and are sequentially transferred to the crimping rolls with the larger crimping width.
Crimp width is applied.

Next, the present invention will be described with reference to the accompanying drawings.

FIG. 1 shows an example of the shape of a graphite molded body obtained by the present invention. This molded body has a trough-like shape with a width of 56 mm and a height of 44 m and a radius of 24 mm at the bottom and a thickness of approximately 0.5 ff1l++, and can be obtained by the apparatus 1 shown in FIG.

FIG. 2 shows a schematic diagram of a continuous forming apparatus for graphite compacts in which the present invention is carried out. Graphite sheet supply roll 2+2at
The graphite sheet 3 supplied from 2b+2c is superimposed and guided between a lower forming roll 4 and a lower forming roll 5 that constitute a pressure forming roll, and is sequentially stacked between a lower forming roll 4a, a lower forming roll 5a, and a lower forming roll. Roll 4b and lower forming roll 5
b. The material is pressure-molded while being guided between the lower forming roll 4c and the lower forming roll 5c. As a method of introducing a stacked graphite sheet, which is made by stacking a plurality of graphite sheets, into a pressure-bonding roll, it is possible to introduce a stacked graphite sheet in advance between the pressure-bonding rolls, or by introducing a stacked graphite sheet between the pressure-bonding rolls. They may be overlapped at the same time.

Each roll rotates at the same speed. Roll gap adjustment handle 6.6a.

Upper molding o-le 5 p 5 a H5 by 6b and 6c
The thickness, density, etc. of the molded product can be changed by raising or lowering b+5c and adjusting the distance between the lower molding rolls. Although FIG. 2 shows a single-support type roll forming machine in which the roll is supported only on one side, a double-support type roll forming machine is preferred.

FIG. 3, FIG. 4, FIG. 5, and FIG. 6 show a lower forming roll and an enlarged front view of the lower forming roll. The apparatus for carrying out the method of the invention is equipped with several sets of crimping rolls. The lower forming rolls are shaped to match the shape of the intended molded product, and those having the same concave surface can be used.

The width of the suppressing convex surface of the lower forming roll is gradually increased so that the crimping width gradually increases. For example, if the first lower forming roll has a width such that the center or one end of the sheet is crimped and integrated with a width of 10 to 20 mm, the second lower forming roll also has a width of 10 to 25 mm. Make the sheet wide enough to pressurize it. The width of the pressing convex surface of the third lower forming roll is made wider so that the sheet can be pressed with a width 10 to 25 mm wider than the crimping width of the second lower forming roll.

In this way, the width of the suppressing convex surface of the lower forming roll is gradually increased, and the width is finally set to be the same as the desired formed object. Therefore, the larger the width of the molded body, the greater the number of rolls required.

It is appropriate to design the amount of increase in the width of the lower forming roll (Δ theory) as follows.

Flat part 20mm≦Δ≦30. mm The curved part differs depending on the radius of curvature (Rmm), and if R is 50wI+ or more, 18 questions ≦Δ≦25 R is 35W
In the case of an~50m1, 13th key ≦Δ≦20 victory R is 20■
~ In the case of 35 shouts, IO key ≦ Δ ≦ 17 kaku R is 10 WII +
In the case of 1 to 20 letters, 8■≦∆≦13 kaku, <, thunder vertical is ∆-,R However, the larger the central angle, the smaller ∆ should be, and the smaller the central angle, the better ∆ should be larger. Curvature 360R360
If the R radius is R1 and the central angle is θ, then ≦Δ≦ 3° (however, θ<160°) is the standard, but Δ should not exceed 25 mm.

The sheet used in the present invention has a density of 0.797cm3~
1.0 g/cFn3, preferably 0.8 g/, -,13
~0.9,! 9/Use the one from Confucian 3. 0.7j
If it is less than i/cm3, the sheet will be brittle and crack easily.If it exceeds 1,09/cm3, a skin layer with metallic luster will be formed on the sheet surface, and the sheet will not have self-adhesive properties even if it is pressed. Not only is it difficult to integrate, but the crimp strength is also weak.Also, the thickness is selected depending on the thickness and density of the desired molded product, but the thicker the material, the greater the brittleness, so it is best to mold a curved surface with a small radius of curvature. When doing so, thick sheets cannot be used and many thin sheets are stacked.Generally, the thickness is 0.25
~0.4 kaku is used.

In the present invention, a sheet with a density of 0.897 cm and a thickness of 0.4977 that satisfies the preferable conditions is shown in FIG.
) and the compact density (117 cm3') are shown in Table 1.

Table 1 In order to properly press and integrate this sheet, it is necessary to make the density of the molded product 1.097 cm3 or more.

Generally, the density of the compact is 0.29 compared to the density of the original sheet.
The density and thickness of the sheet are selected so that the density is 7 cm3 or more, preferably 0.25 g/cm3 or more.

This is the same even if a high-density sheet of 1.5 jJ 7cm3 or more is used, but it is necessary to use a sheet of 1.5 fi/cm3 or more. Forming load is required.

The lower the density of a flexible graphite sheet, the more brittle it becomes and the easier it is to break when it is bent. So the density of the sheet is 0.7g/
(7) If it is less than 3, the sheet itself is likely to break. Furthermore, in order to produce a graphite molded body with a high density, a large number of sheets with a low density must be crimped together, so it is not rational for manufacturing to use a material sheet with a density of less than 0.79/cm@3.

Therefore, unless you want to obtain a molded product with a particularly low density (0.9 g/3 or less), the density is 0. The use of sheets less than '79/cm3 should be avoided. On the other hand, compacts with relatively high density, e.g. density 1.8, li' 7 cm3
, if you want to obtain a molded body with a wall thickness of 05, the density is 1.5g/
The crimp strength is greater when three sheets with a density of 1.0 g/cm3 and a wall thickness of 0.3 mm are crimp-bonded than when three sheets with a wall thickness of crn3 in the 02 column are crimp-bonded. According to the invention, the density is 0.
By using a sheet of 7 to 1.097 cm3, a molded article with a density of 1.0 to 1.897 cm3 can be obtained in good condition. The thickness of the material sheet is set by determining the density of the material sheet and the number of material sheets to be crimped from the density of the formed object and the thickness of the formed object. Since it will be wrapped around r2c, the thickness should be 0.5 to avoid bulk.
It is preferable not to exceed mm. If there is a problem with the thickness, adjust the number of sheets to be crimped.

FIG. 7 shows a schematic cross-sectional view of another example of the shape of a graphite molded body obtained by the present invention. In the case of a molded article having such a wavy cross-sectional shape, the sheet may be pressure-formed in stages from one end to the other end.

For example, the height is 10 mm, the length is 64 m, and the radius of the curved surface is 20.
When obtaining a corrugated molded product as shown in Fig. 7, the first roll crimps and integrates a width of 16 mm from one end, and the second roll crimps and integrates the part crimped and integrated with the first roll. A roll with a width of 32 mm plus the adjacent width of 16 mm is used. Further, the third roll has a width of 48mm, and the fourth roll has a width of 64mm for forming.

FIG. 8 shows a preferred H shape of the upper forming roll used in the present invention. By eliminating the corners of the ends of the suppressing convex surface in this way, it is possible to prevent streaks and scratches from forming on the molded article.

If the method of the present invention is carried out, the air existing inside the graphite sheets and between the sheets during molding will be exhausted, and at the same time, the corresponding parts of each sheet will be pressed together without any force, so no residual stress will be left and no swelling or swelling will occur. There is no upper part 9, and it is possible to continuously mold a molded product having substantially uniform wall thickness, density, and peel strength between sheets, and by appropriately cutting it, a desired length can be obtained.

Hereinafter, the present invention will be explained in more detail with reference to Examples, but the scope of the present invention is not limited to the Examples.

Example 1 A graphite sheet 3 having a density of 0.997 cm3, a thickness of 0.25 mm, and a width of 110 mm was placed on graphite sheet supply rolls 2 and 2a.

2b and 2c are each mounted in a roll form, and the upper forming roll 5 has a width of 15mm, 5a' has a width of 30mm, 5b has a width of 45+Mn, and 5c has a width of 56mm. Four sheets were superimposed and fed between the forming rolls. At this time, the gap between the upper forming roll and the lower forming roll is determined depending on the thickness of the desired formed product, and in this example, the gap is 0.
It was set to 5 mm. The density of the molded body at this time is as follows. In this way, the graphite sheet is formed from forming rolls 4 and 5 to 4.
A and 5a, 4b and 5b, and 4c and 5c were molded under pressure in sequence. Forming rolls 4.5 are used to press-form a width of 15 cm at the center of the formed body, and forming rolls 4a and 5
In a, the width of 15m on both sides adjacent to the width of 15m in the center part which was pressure-molded by 4 and 5 is pressure-molded, and furthermore, the forming roll 4
In b and 5b, the 15 mm width on both sides of the outer side adjacent to the 30 mm width part that was pressure-formed by the forming rolls 4a and 5b is pressure-formed, and then the remaining part is pressure-formed by the forming rolls 4c and 5c. Molding is complete.

The resulting molded product has a cross-sectional shape as shown in Figure 9 (,), and the peel strength between the second and third sheets of this molded product was measured using a Shimadzu Autograph IS-2000. As a result of the measurement, a peel strength chart as shown in FIG. 9(b) was obtained. A, A' are both ends of the gutter-shaped molded body,
B and B' indicate the transition from a curved surface to a flat surface, and C indicates the position of the lowest part of the molded body.

Comparative Example 1 A graphite sheet with the same density and thickness as the graphite sheet used in Example 1 was cut into a width of 110ffi++11 and a length of 70fi, and four sheets were stacked and press-molded using a conventional mold consisting of male and female sets. . The molded body obtained as a result is shown in Figure 10 (,
), and as a result of measuring the peel strength of this molded body in the same manner as in Example 1, a heat peel strength chart as shown in FIG. 10(b) was obtained. In the conventional pressing method using a mold, a minimum value appears on the chart due to residual air, but this is not shown because it is not quantitatively reproducible.

Comparative Example 2 A graphite sheet with the same density and thickness as the graphite sheet used in Example 1 was cut into pieces with a width of 110 mm and a length of 70 mm.
The sheets were stacked one on top of the other and pressure-molded using the isostatic pressing method (FIG. 12). The molded product obtained as a result had a cross-sectional shape as shown in FIG.
A peel strength chart as shown in b) was obtained. 12th
In the figure, 7 is a graphite sheet, 8 is rubber, 9 is a mold (male mold), 10 is a frame material, and 11 is a liquid which is a pressure medium.

Although the hydrostatic press method provides ideal uniform pressure, it is not suitable for mass production or the production of long objects, and the equipment is expensive.

As is clear from the peel strength charts shown in FIG. 9(b), FIG. 10(b), and FIG. 11(b), the method of the present invention is more suitable for mass production than the isostatic pressing method. Although it is suitable and the equipment is inexpensive, it produces graphite compacts with peel strength properties close to those of graphite compacts obtained by isostatic pressing, and far superior to conventional mold press methods. Provides a graphite molded body with excellent peel strength properties. Furthermore, the method of the present invention, like the isostatic pressing method, yields graphite compacts free of residual air.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of the shape of a graphite compact obtained by the present invention, FIG. 2 is a schematic diagram of a continuous molding apparatus for carrying out the method of the present invention, and FIGS. 3, 4, and 5 6 and 6 are schematic front views of the pressure forming roll, and FIG. 7 is a schematic diagram showing another example of the shape of the graphite molded body obtained by the present invention.
FIG. 8 is a schematic diagram of a main forming roll with rounded corners preferably used in the present invention, FIG. 9(a) is a schematic cross-sectional diagram of a graphite molded product obtained by the present invention, and FIG. A peel strength chart of a graphite molded body, FIG. 10 ( ) is a schematic cross-sectional view of a graphite molded body molded with a conventional mold, and FIG. 1O ( b ) is a peel strength chart of the graphite molded body, and FIG. 11 ( a) is a schematic cross-sectional view of a graphite molded body obtained by the isostatic pressing method, 1st
FIG. 1(b) is a one-press strength chart of the graphite molded body, and FIG. 12 is a schematic diagram of an apparatus for the hydrostatic pressing method. 1... Continuous molding device, 2.2 a + 2 b, 2
c...Graphite sheet supply roll, 3...Graphite sheet, 4, 4a. 41) , 4 e ”' lower forming roll, 5, 5a, 5
b. 5c-main forming roll, 6, 6a, 6b,
6 c-Roll gap adjustment knob. Patent applicant: Fukubi Chemical Industry Co., Ltd. Figure 1 Figure 2 Figure 3 Figure 4 Figure 9 (0) Figure 10 Figure 11 1 Figure 12

Claims (3)

[Claims] (1) A graphite sheet stack made by stacking a plurality of flexible graphite sheets is formed by a pair of upper and lower forming rolls each having a roll surface of a predetermined shape, and the crimping width of the stack increases in stages. The graphite sheet is continuously introduced between the crimping rolls with the smallest crimping width in the crimping roll group, and is sequentially transferred to the crimping rolls with the larger crimping width, thereby gradually increasing the crimping width while overlapping the graphite sheets. A continuous molding method for graphite molded bodies characterized by crimping and integrating the entire body. (2) The graphite molded body according to claim (1), wherein the central part of the stacked graphite sheet body is first crimped, and the crimped width is gradually expanded to both ends. Continuous molding method. (3) The graphite molded article according to claim (1), wherein one end of the graphite sheet stack is first crimped, and the crimping width is gradually expanded to the other end. Continuous molding method.