JPS608536A - Carbon brake and manufacture thereof - Google Patents

Abstract

PURPOSE:To increase the friction coefficient and reduce the amount of wear, while prevent fiber from comming off when a brake is operated by arranging carbon fiber which is embedded in a carbon brake, at an angle to a sliding surface. CONSTITUTION:Carbon fiber 1, which is embedded in a carbon brake, is arranged at an angle to a sliding surface. In this case, when the reinforcing material is, e.g., a cloth, although the fiber used in the cloth has generally a sine curve form, the direction of the fiber as a whole can be represented by a straight line. And the direction indicated by this straight line is determined to be the direction of the fiber 2. Thereby, characteristics of high friction coefficient, small amount of wear, and without the comming off of fiber at the time of operating the brake, can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a carbon brake with excellent braking characteristics.

More specifically, it relates to a carbon brake disc or a carbon brake pad in which carbon mtru is oriented at an angle with respect to the sliding surface.

Conventionally, carbon brake discs were compression-molded from the thickness direction, that is, from the sliding surface, so most of the reinforced carbon fibers were almost parallel to the sliding surface. For this reason, there were problems such as a low coefficient of friction and fibers falling off during braking operation, resulting in unstable braking behavior.

In order to improve this, attempts have been made to use relatively long fibers and short fibers and to randomly orient the short fibers (5 mm or less). However, since the long fibers, which are the dominant element, are parallel to the 18 trend, sufficient improvement has not been achieved.

As a result of intensive studies on these problems, the present inventors have found that these problems can be improved by orienting most of the fibers at an angle with respect to the sliding surface.

That is, the present invention provides the following features: (2) The embedded carbon fibers are oriented at an angle If with respect to the sliding surface, and the inner periphery and/or outer periphery is arranged in a rotating manner with unidirectional carbon fibers or carbon fiber fabrics. Carbon brake (3) A cylindrical composite material reinforced with carbon fibers, in which the carbon fiber reinforced thermosetting resin composite material is oriented so as to cross a plane perpendicular to the axis of the cylinder. This method of manufacturing a carbon brake is characterized by cutting the carbon brake in a direction perpendicular to the axis of the carbon brake, and performing sintering and densification in an inert atmosphere before or after the cutting.

In the present invention, the angle of the fiber with respect to the sliding movement refers to the substantially linear direction of the fiber, and does not indicate the angle in the partial micro unit length of the fiber. Preferably, the fibers or their extensions in the direction of the fibers are oriented at an angle such that they extend from one sliding surface to the other opposing surface.

The direction of a+1tIli will be explained with reference to the drawings.

Figures 1 (a) to (c) show the fibers and their directions, 1 shows the fibers and 2 shows the fiber directions. Show direction. Although the fibers used in textiles have a sinusoidal curve, the overall direction of the fibers can be tied in a straight line. The direction represented by this straight line is the direction of the fibers. (
(b) and (c) show cases where the fibers are not regular.

In the present invention, the fibers are oriented at an angle with respect to the sliding surface. This means that the fibers are oriented at an angle with respect to the sliding surface when pressure is applied from the direction of the sliding surface, and as a result, the fibers are oriented in a direction substantially perpendicular to the pressing direction. This is meant to exclude cases where it is oriented.

According to the present invention, the carbon brake has carbon fibers oriented at an angle with respect to the sliding motion.
During brake operation, the friction coefficient is high, the amount of wear is small (and there is almost no shedding of fibers, and it exhibits stable brake operation characteristics.

The carbon brake of the present invention is manufactured by cutting, firing, densification, and optionally heat treatment. Calcining is performed to carbonize organic matter, densification is performed to make the structure denser, and this consists of the steps of impregnation and firing, and heat treatment is mainly performed to improve the thermal oxidation resistance of the material. It is something that can be done.

The carbon fibers used in the present invention are carbon fibers obtained by carbonizing precursors mainly composed of rayon, polyacrylonitrile, pitch, etc. at 800 to 2000°C in an inert atmosphere, or graphite fibers graphitized at temperatures of 2000°C or higher. It is a fiber.

Thermosetting resins used for molding and curing: Refuran, phenol, polyimide, epoxy, etc./Resins that have high viscosity or are solid must be dissolved in an appropriate solvent or melted by heating.

Further, in order to make it dense, the composite material is impregnated with various resins such as furan and phenol, or coal tar pitch, and then fired in an inert atmosphere such as nitrogen or argon.

This densification can also be performed by heating the composite material to 700-2000°C in a non-oxidizing atmosphere such as nitrogen, hydrogen, or argon, and introducing a hydrocarbon gas such as methane, ethane, or benzene. Yes (Chemical Paper Deposition).

Further, heat treatment is usually performed to change the carbon arrangement structure and improve thermal oxidation resistance. This heat treatment was performed at 2000 to 3000°C in an inert gas atmosphere.
It is done by This heat treatment not only improves thermal oxidation resistance but also has the effect of facilitating impregnation with resin, etc. during densification. If necessary, densification and heat treatment are repeated until predetermined characteristics are obtained.

The carbon brake of the present invention is useful for aircraft, railway vehicles, automobiles, and motorcycles, and is particularly useful for multi-type disc brakes for aircraft.

Next, a method for manufacturing the carbon brake disc of the present invention will be explained.

1) Flow molding method A mixture of carbon fibers with a fiber length of 5 to 40 mm and a thermosetting resin (e.g., phenol, furan, epoxy, polyimide resin, etc.) is flowed in the axial and longitudinal directions of a cylindrical shape. After orienting the fibers in the flow direction, the resin is cured to form a cylindrical molded product. Next, a disc-shaped molded product is obtained by cutting the molded product in a direction perpendicular to the axial direction (radial direction) of the cylinder, that is, into slices.

Next, the temperature of the disc-shaped molded product is gradually increased in an inert atmosphere and heated and fired to 800 to 1500°C, thereby converting the matrix resin into a carbonaceous material. Depending on the shape of the molded product and the operability of the process, the cylindrical molded product may be fired in an inert atmosphere and then cut into a disc-shaped carbon material.

Next, the carbon material is impregnated with a liquid organic substance such as pitch or furan resin, and then densified by firing in an inert atmosphere. This densification can also be achieved by the chemical paper deposition (commonly known as CVD) method, in which the carbon material is held in a high-temperature inert atmosphere and the introduced hydrocarbon gas is thermally decomposed to deposit carbon. .

2) Filament winding method A method in which carbon fiber filaments 1 to 1 impregnated with a thermosetting resin such as phenol resin or furan resin are wound around a predetermined mandrel at an angle in the circumferential direction (direction perpendicular to the axial direction of the mandrel). After obtaining a cylindrical molded product, the carbon brake of the present invention is obtained by firing in an inert atmosphere, cutting into a disk shape, densification, and heat treatment.

A tape such as carbon m141 fabric may be used instead of carbon fiber filaments.

3) Cross rolling method Carbon fiber filament cloth impregnated with thermosetting resin or Carbon I! i-fiber spun yarn cloth After being wound and laminated on a fixed mandrel and cured, cutting process, 1L densification,
Perform heat treatment, etc.

Firing (carbonization) for manufacturing the carbon brake of the present invention
The order of steps such as densification, heat treatment, and cutting is not particularly fixed. Further, it is preferable that the densification and heat treatment be repeated.

Furthermore, either densification or heat treatment may be performed first. That is, heat treatment is performed after firing, followed by densification, or vice versa.

Cutting is done at some stage after initial resin curing. However, if the cutting is performed before densification, the material is slow and difficult to process. Therefore, cutting is preferably performed at several stages of densification and heat treatment. Densification after cutting can further enhance the densification effect. This is because cutting increases the surface area.

To facilitate cutting, perform cutting before firing one culm for densification. This is because the non-carbonized resin acts as a binder and prevents damage to the fragile carbon material 1'31.

According to the method of the present invention, a large number of carbon brakes can be manufactured at the same time, and production efficiency can be improved.

As described above, in the case of the carbon material of the present invention in which the carbon fibers are oriented at an angle to the sliding surface, compared to the conventional carbon material in which the carbon fibers are approximately parallel to the sliding surface, the carbon fibers are oriented in the circumferential or radial direction. Although the strength tends to decrease, there is no problem under normal usage conditions. When high strength is required under severe usage conditions, unidirectional carbon fibers or carbon fiber fabrics may be laminated and reinforced on the outer periphery and/or the inner periphery as described below. This reinforcement is particularly effective for fixing notches on the outer or inner circumference of disc brakes and the like. In the case of reinforcing this notch, the composite material is cut to a size slightly smaller than a predetermined shape, and then carbon fibers are laminated in a spiral manner to obtain a predetermined shape. On the outer or inner periphery of a composite material in which the embedded carbon fibers are oriented at an angle to the sliding surface, unidirectional carbon fiber strips or carbon fiber fabrics are swirled around the outer and inner periphery to cure the composite material. It may be used before, after curing, after firing, after densification, or after heat treatment.

In the case of the flow molding method, carbon fibers impregnated with a thermosetting resin can be swirled and laminated on the outer periphery of the cavity of the female mold or the outer periphery of the male mold to be used, and then molding can be performed by the flow molding method.

Further, in the manufacturing method using a mandrel, unidirectional carbon fibers or carbon fiber fabrics impregnated with a thermosetting resin in advance are laminated in the circumferential direction of the mandrel, and then formed by the filament winding method or cross rolling method.

Alternatively, in any of the above methods, carbon fibers impregnated with a thermosetting resin are laminated by rotation at any stage after shaping, cutting, firing, densification, or heat treatment, and then hardening, firing, etc. I do.

EXAMPLES Hereinafter, the present invention will be explained with reference to examples, and comparative examples will be shown.

Example Contains resin for bundling carbon fiber filaments impregnated with Luzole type phenolic resin! (Re) (32% by weight) was cut into 20 mIn pieces to create chopped strand prepreg.

This prepreg was filled into the female mold center part of the mold shown in Figure 2, and heated to 170"C120kg/'cm2 using a hot press.
．． After curing for 60 minutes, a cylindrical composite material was produced. After cutting and removing 15 mm of the upper and lower ends of this composite material, the thickness was 10 mm.
Cut into rounds, outer diameter 115mm, inner diameter 55mm, thickness 10mm.
A disk-shaped composite material of mm was produced.

The composite material was heated to 1000° C. at 2° C./min in a nitrogen atmosphere and held for 30 minutes to change the organic matrix to carbonaceous (firing step).

In order to make this carbon material dense, it was impregnated with pitch at 200° C. under reduced pressure, and then fired.

After repeating this impregnation and firing process 5 times, 2
After raising the temperature to 2000℃ at 00'C/hr, heat treatment was performed by holding it for 30 minutes, resulting in a density of 1.65g/cm'' and an outer diameter of 11.
A carbon brake with a diameter of 5 mm, an inner diameter of 55 mm, and a thickness of 10+11111 mm was manufactured.

When the carbon brake was cut perpendicular to the sliding direction (disc surface) and the m-fiber orientation of the cross section was observed, most of the fibers were oriented almost perpendicular to the sliding direction.

Example 2 A #plain fiber filament bundle (RC 35% by weight) impregnated with resonyl type phenolic resin was filament-winded onto a mandrel with an outer diameter of 55+nm so as to form an angle of 60'' with the axial direction of the mandrel. Cured for 2 hours, length approximately 500,111 m, outer diameter 115 m
A cylindrical composite material of 155 mm in m 1 was produced.

The composite material was subjected to a firing process in the same manner as in Example 1.

Next, 50 mm of both ends were cut off, the pieces were cut into rings with a thickness of 1101 nm, and after being processed to have an outer diameter of 115 mm and an inner diameter of 55 mm, densification and heat treatment were performed in the same manner as in Example 1.
A carbon disk with a density of 1.65 g/cm'' was prepared.

Example 3 Carbon 41i fiber spun yarn uNh manufactured by Toho Bethlon Co., Ltd.
(8 sheets of satin 320g/m') for Franc $741J
tt (Hitafuran V F-302, touch fly', 0,
After applying 40og/m2 of 5 wt% (containing 5 wt%) and breguring at 70'C for 30 minutes, the outer diameter of 11 was applied to a mandrel with an outer diameter of 55 mm so that the Vf (fiber volume content) was 35%.
The layers were laminated by rotation to a thickness of 5 ml+ and heated and cured at 150°C for 2 hours.

This laminate was fired, cut, densified and heat treated in the same manner as in Example 2 to produce a carbon disk with a density of 1.60 g/am1.

Example 4 Cut after hardening in Example 7, outer diameter 115 mm,
Carbon fiber unidirectional prepreg impregnated with resol-type phenolic resin was laminated circumferentially to a thickness of 1 mm on the outer and inner peripheries of a disk-shaped composite material with an inner diameter of 501 Il 11 and a thickness of 10 V++, and then fired in the same manner as in Example 1. Densified and heat treated, outer diameter 117mm, inner diameter 48n+m, thickness 1
A 0 mm carbon disc was obtained.

Comparative Example 1 A chopped strand prepreg produced in the same manner as in Example 1 was subjected to ordinary compression molding using a mold as shown in FIG.
A cylindrical composite material of llllln was produced.

This composite material was subjected to cutting, firing, densification, and heat treatment in the same manner as in Example 1 to produce a carbon brake having a density of 1.65 g/cm', an outer diameter of 115 mm, an inner diameter of 55 mm, and a thickness of 10 mm. .

When the carbon brake was cut at right angles to the sliding surface and the ll1m orientation of the cross section was observed, all the fibers were oriented almost parallel to the sliding direction.

Comparative Example 2 A prepreg was produced in the same manner as in Example 1 using a carbon fiber spun 7-strand fabric manufactured by Toho Bethlon Co., Ltd., and the outer diameter was 1.
A cylindrical composite material having a diameter of 10 mm and an inner diameter of 55 mm was prepared in the same manner as in Comparative Example 1 using the mold shown in FIG. This composite material was subjected to cutting, firing, densification, and heat treatment in the same manner as in Example 1, and the density was 1.65 (1/CmX, outer diameter 115
A carbon brake with an inner diameter of 55 mm and a thickness of 110 nm was produced.

When the carbon brake was cut perpendicular to the sliding direction and the m-fiber orientation of the cross section was observed, all the fibers were oriented almost parallel to the sliding direction.

[Brief explanation of the drawing]

Figure 1 (a), (b), and (c) show the fiber direction, Figure 2 is a cross-sectional schematic diagram of the mold used in Example 1, and Figure 3 is the mold used in Comparative Example 1. FIG. 3 is a schematic cross-sectional view of the mold. 1: Fiber, 2: Fiber direction, 3: Male type, 4: Field type

Claims (4)

[Claims] (1) A carbon brake in which embedded carbon fibers are oriented at an angle to the sliding surface. (2) A carbon brake in which embedded carbon fibers are oriented at an angle to the sliding surface, and the inner circumference and/or outer circumference is arranged in a rotating manner using unidirectional carbon fibers or carbon fiber fabrics. (3) A cylindrical composite material using carbon fiber as a reinforcing material,
The carbon fiber-reinforced thermosetting resin composite material whose fibers are oriented to cross a plane perpendicular to the axis of the cylinder is cut in a direction perpendicular to the axis of the cylinder, and before or after the cutting, the carbon fiber-reinforced thermosetting resin composite is placed in an inert atmosphere before or after the cutting. A method for manufacturing a carbon brake, characterized by performing firing and densification in a carbon brake. (4) The manufacturing method according to claim (3), which is characterized in that heat treatment is performed after firing and densification.