JP6780972B2 - Plate-shaped spring made of carbon / carbon composite material and bent in a zigzag shape - Google Patents

Description

The present invention relates to a zigzag, plate-like spring made of a carbon / carbon composite material capable of exhibiting its performance particularly when used in a high temperature environment.

Spring is used as a mechanical element in various machines, devices, and mechanisms, and today it is an indispensable and important part in household products, industrial products, and other fields.

Conventionally, the spring is generally manufactured of a metal material, and stainless steel, low alloy steel, tool steel, titanium alloy and the like have been mainly used. However, springs made of metal materials are inferior in heat resistance and cannot exhibit sufficient spring characteristics in a high temperature usage environment, and therefore cannot be used or can not be used for a long period of time.

For example, even if the spring is made of a material called a heat-resistant alloy, if the temperature exceeds 400 ° C, the strength is significantly reduced and the deformation is remarkable, and a sudden settling phenomenon occurs. Therefore, as a spring in such a high temperature environment. Could not be used.

When the spring is used at an environmental temperature exceeding 400 ° C., the spring may be manufactured using a super heat-resistant alloy such as Inconel or Hastelloy, but even with such a super heat-resistant alloy, the temperature should be 700 ° C. If the temperature exceeds the temperature, the strength is significantly reduced and the deformation is remarkable, and a sudden settling phenomenon occurs. Therefore, the spring cannot be used in such a high temperature environment.

Furthermore, coil springs are also manufactured using ceramics such as silicon nitride and zirconia instead of super heat-resistant alloys such as Inconel and Hastelloy, but such ceramic coil springs originally have low toughness. Since it is vulnerable to thermal shock, it is highly likely to be destroyed if it is used repeatedly in a high temperature environment. Further, at a high temperature exceeding 500 to 1000 ° C., the strength is rapidly lowered, which may lead to breakage.

In order to solve such a problem, a coil spring made of a carbon / carbon composite material (also referred to as a C / C composite) is manufactured (see Patent Document 1). The carbon / carbon composite material (also called C / C composite) is a fiber-reinforced composite material in which carbon fibers, which are reinforcing fibers, are hardened with graphite or a matrix of carbon, and is several times as large as that of a conventional carbon material or graphite material. Because it has excellent heat resistance, abrasion resistance, and toughness, as well as strength and elasticity, nose caps for spacecraft, leading edges of wings, aircraft, racing cars, Shinkansen vehicles, large heavy vehicles, etc. It is a material that has been used for brakes, structural materials in heat treatment furnaces, trays, heaters, product handling forks in semiconductor manufacturing furnaces and solar cell manufacturing furnaces, high temperature jigs for metal processing, and the like.

The coil spring made of carbon / carbon composite material disclosed in Patent Document 1 is, for example,
(1) The raw material, preformed yarn, is made into yarn, tape, or sheet, and then
(2) The preformed yarn is wound around a core rod which is a mold together with a coil material (mold) for holding a gap, and the raw material preformed yarn and the coil material (mold) are alternately arranged.
(3) Molded by hot pressing at about 300 to 2000 ° C. under normal pressure or pressure.
(4) Remove the coil material (mold) from the molded product and remove it.
(5) It is manufactured by carbonizing at 700 to 1200 ° C. as needed and then graphitizing at 1500 to 3000 ° C.

In the coil spring made of a carbon / carbon composite material disclosed in Patent Document 1, the preformed yarn is wound around a core rod which is a mold in the manufacturing process together with a coil material (mold) for holding a gap, and the raw material preformed yarn is used. And the coil material (mold) are arranged alternately, and after molding, it is necessary to remove the coil material (mold) from the core rod which is the mold, so that there is a problem that it takes too much manpower to mass-produce.

Further, since the coil spring made of the carbon / carbon composite material disclosed in Patent Document 1 adopts the manufacturing method as described above, the carbon fiber which is the reinforcing fiber of the carbon / carbon composite material has a spiral shape of the coil spring. Since it was composed of a carbon / carbon composite material as a so-called unidirectional reinforcing material oriented only in the longitudinal direction of the spiral along the line, the strength and elastic modulus (such type) can be used as a spring. Although the shear modulus of the spring is particularly important), the shear modulus is low as a coil spring that supports a large load, and it cannot be said that the spring has a sufficient function.

Japanese Unexamined Patent Publication No. 6-264497

The present invention has been made in view of the above-mentioned technical background, and is a spring that can be used repeatedly even in a high temperature environment exceeding 1000 ° C., has a simple manufacturing process, and can be mass-produced. It is an object of the present invention to provide a spring having a high shear modulus capable of supporting a large load.

In order to solve the above problems, the inventors first conceived that instead of the coil-shaped spring, a plate-shaped spring bent in a zigzag shape is composed of a carbon / carbon composite material.
Further, in the flat plate-shaped carbon / carbon composite material, the inventors have compared the carbon fiber as a unidirectionally reinforced carbon / carbon composite material in which carbon fibers as a reinforcing material are aligned in one direction in the in-plane direction of the flat plate. We found that the carbon fibers were randomly oriented in the plane and the shear elasticity in the plane of the two-dimensional randomly oriented carbon / carbon composite material laminated in layers was dramatically improved. The present invention was conceived by applying this fiber orientation to a carbon / carbon composite material of a plate-shaped spring bent in a zigzag shape.

That is, in the invention according to the first aspect, in a plate-shaped spring that bends in a zigzag shape in the XY axis plane and has a predetermined width in the Z-axis direction, the plate-shaped spring is composed of a carbon / carbon composite material. It has a structure in which short fibrous carbon fibers, which are reinforcing fibers, are randomly oriented in two dimensions in the XY axis plane, and short fibrous carbon fibers, which are two-dimensionally randomly oriented in the Z axis direction, are layered . It was a plate-shaped spring.

Further, in the invention according to the second aspect, in the method for manufacturing a plate-shaped spring according to the first aspect , in the plate-shaped spring, short fibrous carbon fibers which are reinforcing fibers are two-dimensionally randomly oriented. The method used was to manufacture a plate-shaped spring having a structure formed by cutting from a laminated plate made of carbon / carbon composite material .

In the present invention, as a result of forming a zigzag bent plate spring made of a carbon / carbon composite material having the above-mentioned structure, the spring can be repeatedly used even in a high temperature environment exceeding 1000 ° C. It has become possible to provide a spring that is simple and can be mass-produced.
Further, it has become possible to provide a spring having a high shear modulus capable of supporting a large load.

FIG. 1 shows a typical example of a plate-shaped spring made of a carbon / carbon composite material and bent in a zigzag shape according to the present invention. FIG. 2 shows a laminated plate made of carbon / carbon composite material in which short fibrous carbon fibers, which are reinforcing fibers, are two-dimensionally randomly oriented from a plate-shaped spring made of carbon / carbon composite material which is bent in a zigzag shape according to the present invention. It shows the state of being machined by cutting from.

Hereinafter, a plate-shaped spring made of a carbon / carbon composite material and bent in a zigzag shape according to the present invention will be described.
The carbon / carbon composite material (also called C / C composite) is a fiber-reinforced composite material in which carbon fibers, which are reinforcing fibers, are hardened with graphite or a matrix of carbon, and is several times as much as a conventional carbon material or a graphite material. It is a material that has the strength and elastic modulus of graphite, and also has excellent heat resistance, abrasion resistance, and toughness. Further, the carbon / carbon composite material is also known as a material having a high specific strength and a high specific composition because of its low specific gravity and high strength and rigidity (elastic modulus).

The carbon / carbon composite material is one in which carbon fibers are oriented in only one direction, one in which carbon fibers are oriented in two directions in a plane, one in which carbon fibers are three-dimensionally oriented in three directions, and carbon fibers (short fibers). In addition to those in which carbon fibers (short fibers) are three-dimensionally randomly oriented in a plane, those in which carbon fibers are oriented in various patterns have been devised so far.

Regarding the manufacturing method of carbon / carbon composite material, in addition to the resincher method, the CVD method, the manufacturing method using preformed yarn, etc., short fibrous carbon fiber, binder pitch powder, coke powder, and stickiness A manufacturing method using a sheet-shaped intermediate material composed of a binder has been developed.

FIG. 1 shows a typical example of a plate-shaped spring 1 made of a carbon / carbon composite material and bent in a zigzag shape according to the present invention. The spring 1 is a zigzag shape and is composed of a main body portion 2 bent in a plurality of stages, one end side 3 and the other end side 4. The number of bending steps, the width dimension w, the thickness dimension t, and the slit dimension ts of the main body portion 2 are set from the load used by the plate-shaped spring 1 bent in a zigzag shape, the amount of deflection, and the like.

The zigzag bent plate-shaped spring 1 made of carbon / carbon composite material can be used for both tension and compression, and has different ends (one end side 3 and others) for tension and compression. The shape of the end side 4) is determined, and the free height of the spring 1 and the like are set respectively.

The plate-shaped spring 1 bent in a zigzag shape shown in FIG. 1 is shown as an example, and is not limited to the spring having the appearance shown in FIG. For example, in the plate-shaped spring 1 bent in a zigzag shape in FIG. 1, in addition to the width dimension w, the thickness dimension t, and the slit dimension ts, the L dimension in the drawing has a constant dimension in each bent stage. However, these dimensions may have a shape that changes for each stage, or may change continuously or discontinuously for each stage.

Next, an example of a method for manufacturing a plate-shaped spring 1 made of a carbon / carbon composite material and bent in a zigzag shape according to the present invention will be described.
In the present embodiment, a plate-shaped spring made of a carbon / carbon composite material using a sheet-like intermediate material composed of short fibrous carbon fiber, binder pitch powder, coke powder, and a binder is bent into a zigzag shape. The manufacturing method of No. 1 will be described.

The sheet-like intermediate material for producing the carbon / carbon composite material used in the present embodiment is composed of short fibrous carbon fibers, binder pitch powder, coke powder, and a binder.

The carbon fiber used in the present embodiment may be any of polyacrylonitrile (PAN) -based, rayon-based, and pitch-based yarns, and any of flame-resistant yarns, carbonized yarns, and graphitized yarns. You can also use things. In the present embodiment, the carbon fibers are in the form of short fibers, and the fiber length is not particularly limited, but the length is preferably 1 to 50 mm, and further if the length is 1 to 25 mm. preferable.

The binder pitch powder used in the present embodiment is a petroleum and / or coal-based binder pitch powder having softness, has a softening temperature in the range of 60 to 320 ° C., and has a quinoline insoluble content of 0 to 80 weight. It can be an isotropic, latently anisotropic, or anisotropic binder pitch obtained from petroleum and / or coal having a percentage and a volatile content of 10 to 60% by weight.

This binder pitch powder is used for binding reinforcing fibers (carbon fibers) and coke powder described later as an aggregate, and the average particle size thereof is preferably 0.5 to 60 microns. More preferably, it is 3 to 20 microns.

Further, the coke powder used in the present embodiment is a petroleum and / or coal-based coke powder having no softening property, which is intended to have an aggregate role and does not have a softening point. The volatile content is 10% by weight or less, preferably 2% by weight or less. As the coke powder, either petroleum-based or coal-based powder can be used, and the average particle size thereof is preferably 0.5 to 30 microns, more preferably 1 to 20 microns.

The blending ratio of the softening petroleum and / or coal-based binder pitch powder and the non-softening petroleum and / or coal-based coke powder is not particularly limited, but the binder pitch / by weight ratio. Coke = 90/10 to 10/90 is preferable, and 70/30 to 30/70 is more preferable.

In addition, the binder used in the present embodiment is used to adhere the binder pitch powder and the coke powder, and to adhesively bond the mixture of the binder pitch powder, the coke powder, and the binder to the carbon fibers. It is a thing. As the binder, those industrially used as thickening stabilizers (or pastes) such as methyl cellulose can be used, and naturally-derived thickening stabilizers and chemically synthesized thickening stabilizers can be used. Any of the stabilizers can be used.

An organic solvent such as alcohol or water can be used as the dispersion liquid to be added to the mixture of the binder pitch powder, the coke powder, and the binder. The volume content of the carbon fibers is preferably 5 to 70% by volume, preferably 20 to 60% by volume, based on the total volume of the intermediate materials.

The sheet-shaped intermediate material used in the present embodiment is manufactured through the following steps.
(1) A step of forming a mixed solution by mixing a binder pitch powder, a coke powder, a binder, and a dispersion liquid in a predetermined compounding ratio.
(2) A step of uniformly dispersing the short fibrous carbon fibers in the mixed solution by putting the mixed solution and a predetermined amount of short fibrous carbon fibers in the mixing tank and stirring the mixture.
(3) A step of pumping a mixed solution in which short fibrous carbon fibers are dispersed and mixed from a mixing tank to a paper machine, which is a known technique, for paper making.

In the sheet-like intermediate material thus obtained, the short fibrous carbon fibers are two-dimensionally and randomly oriented in the sheet surface, and are arranged in a non-woven fabric shape in a state of being entangled with each other. Then, the continuous sheet-like non-woven fabric composed of the short fibrous carbon fibers and the binder pitch powder, the coke powder, and the binder arranged around the short fibrous carbon fibers is a binder blended in the mixed solution. It has a predetermined tackiness depending on the agent.

Next, a method of manufacturing a plate-shaped spring 1 made of a carbon / carbon composite material and bent in a zigzag shape by using the sheet-shaped intermediate material described above will be described.
First, the sheet-shaped intermediate material produced by the above-mentioned method is cut into a predetermined size and stacked in a plurality of layers. The number of sheet-like intermediate materials to be stacked is determined by the required plate thickness of the finally obtained carbon / carbon composite material.

After arranging a plurality of stacked sheet-shaped intermediate materials in a hot press mold, they are pressure-baked at about 300 to 2000 ° C. and normal pressure to 500 kg / cm ² in a hot press to form a plate (laminated plate 10). Mold into. After pressure firing, the laminated plate 10 formed from the hot press mold is taken out, and then carbonized at 700 to 1200 ° C. and graphitized at 1500 to 3000 ° C. as necessary to laminate the carbon / carbon composite material. Obtain plate 10.

Next, a step of cutting out a plate-shaped spring 1 bent in a zigzag shape from a laminated plate 10 made of a carbon / carbon composite material by machining will be described with reference to FIG.
FIG. 2 shows a state in which a plate-shaped spring made of a carbon / carbon composite material and bent in a zigzag shape is cut out from a laminated plate 10 made of a carbon / carbon composite material by cutting.

In FIG. 2, the Z-axis direction indicates the direction in which the sheet-shaped intermediate materials in which the carbon fibers are two-dimensionally and randomly oriented are laminated. Therefore, in the molded carbon / carbon composite material laminated plate 10, the short fibrous carbon fibers are two-dimensionally and randomly oriented in the XY axis plane, but are short fibrous in the Z axis direction. The carbon fibers are not oriented.

Therefore, the plate-shaped spring 1 bent in a zigzag shape is machined from the laminated plate 10 made of carbon / carbon composite material with the direction as shown in FIG. 2 by machining, so that the inside of the XY axial plane is formed. It is possible to obtain a plate-shaped spring 1 that is bent in a zigzag shape and has a predetermined width in the Z-axis direction and is bent in a zigzag shape. Since such a processing method can be adopted, if a laminated plate 10 made of a carbon / carbon composite material having a predetermined size is manufactured, a large amount of plate-shaped springs 1 bent in a zigzag shape can be produced by machining. It will be possible to produce in.

By using the processing method as described above, the short fibrous carbon fibers, which are reinforcing fibers, are two-dimensionally randomly oriented in the XY axis plane, and the short fibrous carbon fibers are two-dimensionally randomly oriented in the Z-axis direction. It is possible to obtain a plate-shaped spring 1 bent in a zigzag shape having a structure in which fibers are layered.

When such a plate-shaped spring 1 bent in a zigzag shape is used as a compression spring or a tension spring, the load-deflection characteristic of the plate-shaped spring 1 is XY of each plate bent in a zigzag shape of the plate-shaped spring 1. It is determined by the bending rigidity in the axial plane (the bending rigidity is determined by the tensile elastic modulus of each plate bent in a zigzag shape) and the shear rigidity.

In a flat plate-shaped carbon / carbon composite material, the tensile modulus of a unidirectionally reinforced carbon / carbon composite material (fiber content Vf = 40%) in which carbon fibers as a reinforcing material are aligned in one direction in the in-plane direction of the flat plate. The modulus and shear modulus and the tensile modulus and shear modulus in the XY axial planes of the carbon / carbon composite material laminate 10 (fiber content Vf = 40%) obtained by the above-mentioned manufacturing method. By comparison, the unidirectionally reinforced carbon / carbon composite material in which the carbon fibers were aligned in one direction in the in-plane direction of the flat plate had a tensile modulus of 100 GPa and a shear modulus of 4.6 GPa.
On the other hand, the laminated plate 10 made of carbon / carbon composite material obtained by the above-mentioned production method had a tensile elastic modulus of 50 GPa and a shear elastic modulus of 17 GPa.

That is, although the tensile elastic modulus of the carbon / carbon composite laminate 10 obtained by the above-mentioned manufacturing method and the tensile elastic modulus of the unidirectionally reinforced carbon / carbon composite material have substantially the same values, the above-mentioned manufacturing method The shear modulus of the obtained laminated plate 10 made of carbon / carbon composite material is 3.7 times that of the unidirectionally reinforced carbon / carbon composite material, and the carbon / carbon composite material obtained by the above-mentioned manufacturing method. It was found that the shear rigidity of the laminated plate 10 made of the above product was extremely high.

Therefore, in the case of the plate-shaped spring 1 bent in a zigzag shape that needs to support a large load, short fibrous carbon fibers, which are reinforcing fibers, are two-dimensionally randomly oriented in the XY axial planes as described above, and Z It is desirable that the short fibrous carbon fibers, which are two-dimensionally randomly oriented in the axial direction, have a layered structure.

When it is not necessary to support such a large load, a plate-shaped spring 1 bent in a zigzag shape may be manufactured by a manufacturing method different from the manufacturing method described above.

For example, a plurality of sheet-shaped intermediate materials are laminated, placed in a hot press mold having a zigzag bent cavity, and pressed by a hot press at about 300 to 2000 ° C. and normal pressure to 500 kg / cm ^2. It is also possible to adopt a manufacturing method in which the product is finished in the shape of a plate-shaped spring that is bent in a zigzag shape by firing. After forming into the shape of a plate-shaped spring bent in a zigzag shape, carbonization treatment may be performed at 700 to 1200 ° C. and graphitization treatment at 1500 to 3000 ° C., if necessary.

Alternatively, a sheet-like intermediate material (intermediate material of unidirectional material) in which carbon fibers as a reinforcing material are aligned in one direction in the in-plane direction of a flat plate, or a plain weave or satin weave using carbon fibers is woven. A sheet-shaped intermediate material using a cloth material (intermediate material of the cloth material) is manufactured by the same method as the sheet-shaped intermediate material in which carbon fibers are two-dimensionally and randomly oriented as described above, and is unidirectional. an intermediate material of the intermediate material and cloth material of the wood laminating a plurality, placed in a hot press mold having a cavity that is bent it to zigzag, about 300 to 2000 ° C. in a hot press, a normal pressure ~500kg / cm ² It is also possible to adopt a manufacturing method in which the shape of the plate-shaped spring is finished in the shape of a plate-shaped spring that is bent in a satin-fold shape by pressure-baking with

In addition, a sheet-like intermediate material (intermediate material of unidirectional material) in which carbon fibers, which are reinforcing materials, are aligned in one direction in the in-plane direction of a flat plate, and carbon fibers are woven into a plain weave or a red woven material. A sheet-shaped intermediate material using a cloth material (intermediate material of the cloth material) is laminated in the Z direction shown in FIG. 2, and the carbon / carbon material is pressure-fired to have a direction as shown in FIG. Alternatively, the plate-shaped spring 1 bent in a zigzag shape may be machined from the laminated plate 10 made of carbon / carbon composite material by machining.

In the above cases as well, after forming into the shape of a plate-shaped spring bent in a zigzag shape, carbonization treatment may be performed at 700 to 1200 ° C. and graphitization treatment at 1500 to 3000 ° C., if necessary.

Further, in the above description, a method of manufacturing a plate-shaped spring 1 bent in a zigzag shape by using an intermediate material having a specific configuration has been described, but the present invention is not limited thereto. An intermediate material having a structure different from that described above may be used, or a plate-shaped spring 1 bent in a zigzag shape may be manufactured by a resin method or a CVD method.

1 Plate-shaped spring bent in a zigzag shape 2 Main body 3 One end side 4 One end side 10 Laminated plate

Claims (2)

A plate-shaped spring that bends in a zigzag shape in the XY-axis plane and has a predetermined width in the Z-axis direction, and the plate-shaped spring is made of a carbon / carbon composite material.
The short fibrous carbon fibers that are reinforcing fibers are two-dimensionally randomly oriented in the XY axis plane, and the short fibrous carbon fibers that are two-dimensionally randomly oriented in the Z-axis direction have a layered structure. A characteristic plate-shaped spring. The method for manufacturing a plate-shaped spring according to claim 1.
The plate-shaped spring is a method for manufacturing a plate-shaped spring , wherein short fibrous carbon fibers, which are reinforcing fibers, are formed by cutting from a laminated plate made of a carbon / carbon composite material that is two-dimensionally randomly oriented.