JP6910211B2 - Carbon / carbon composite spring element and its manufacturing method - Google Patents

Description

The present invention relates to a spring element made of a carbon / carbon composite material, which can exhibit its performance particularly when used in a high temperature environment, and more specifically, can be used as a spring washer in a high temperature environment. The present invention relates to a spring element and its manufacturing method.

Spring elements that can be used as spring washers are used as mechanical elements in various machines, devices, and mechanisms, and today, they are indispensable and important parts in household products, industrial products, and other fields. It has become.

Conventionally, the spring washer 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, spring washers made of metal materials are inferior in heat resistance and cannot exhibit sufficient spring characteristics in a high temperature environment, and therefore cannot be used in a high temperature environment or in a high temperature environment. Long-term use is not possible.

For example, even a spring washer made of a material called a heat-resistant alloy has a remarkable decrease in strength and deformation at a temperature exceeding 400 ° C., and a sudden settling phenomenon occurs. Therefore, a spring is used in such a high temperature environment. Could not be used as a washer.

When the pulling washer is used at an environmental temperature exceeding 400 ° C., a spring washer can be manufactured using a super heat-resistant alloy such as Inconel or Hastelloy. Even with such a super heat-resistant alloy, the temperature is 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, spring washers can be manufactured using ceramics such as silicon nitride and zirconia instead of super heat-resistant alloys such as Inconel and Hastelloy, but such ceramic spring washers originally have low toughness and are resistant to thermal shock. Because it is weak, 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 spring washer made of a carbon / carbon composite material (also referred to as a C / C composite) is disclosed (see Patent Document 1). A carbon / carbon composite material (also called a 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 a conventional carbon material or a graphite material. Because of its strength and elastic modulus, as well as excellent heat resistance, abrasion resistance, and toughness, nose caps for spacecraft, leading edges of wings, 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 spring washer made of carbon / carbon composite material disclosed in Patent Document 1 was manufactured by the following manufacturing method.
(1) Tensile Strength 200 kg / mm ² or more, and a prepreg braided tensile modulus 24,000 kg / mm ² or more bundles or sleeve-like carbon fiber was heated wound in a spiral groove of the jig, is semi-cured,
(2) Next, the semi-cured coiled molded body was removed from the jig, further heated, and completely cured to obtain a coiled molded body.
(3) Next, the coiled molded body is carbonized, impregnated with pitch or the like as necessary, fired, and graphitized to obtain a coiled material of CCM (carbon / carbon composite material).
(4) Further, a CCM spring washer is obtained by cutting and separating each turn.

Since the spring washer made of a carbon / carbon composite material disclosed in Patent Document 1 employs the above-mentioned manufacturing method, the carbon fiber, which is a long fiber, extends along the wire of the coil or the coil. Since the fiber orientation was further spirally extended along the strands of the spring washer, it had enough strength and elasticity to be used as a spring washer (in the spring washer, torsional rigidity is particularly important). However, as a spring washer that supports a large load, its torsional rigidity is low, and it cannot be said that it is performing its sufficient function.

Further, since the spring washer made of carbon / carbon composite material disclosed in Patent Document 1 adopts the manufacturing method as described above, a jig having a spiral groove is required for each different washer diameter. In addition, since the carbon / carbon composite material molded into a coil shape was cut and separated for each turn, mass production was difficult and the cost was high.

Japanese Unexamined Patent Publication No. 9-07924

The present invention has been made in view of the above-mentioned technical background, and is a spring element that can be repeatedly used even in a high temperature environment exceeding 1000 ° C. and has high torsional rigidity capable of supporting a large load. An object of the present invention is to provide a spring element that has a spring element and can be used as a spring washer.

In order to solve the above problems, in the invention according to the first aspect, the spring element is a spiral annular spring element, and the spring element has a layer structure in which the spring element is laminated in parallel with the surface facing the central axis direction of the spring element. A spiral annular spring element having a structure made of a two-dimensional carbon / carbon composite material.

Further, in the invention according to the second aspect, in the spiral annular spring element of the invention according to the first aspect, the two-dimensional carbon / carbon composite material is a surface of the carbon fiber nonwoven fabric facing the central axis direction of the spring element. A spiral annular spring element having a layer structure in which the spring elements are laminated in parallel with each other is used.

Further, the invention according to the third aspect is a method for manufacturing a spiral annular spring element.
A sheet in which carbon fibers are oriented in one direction, or a flat carbon / carbon composite material or a precursor of a carbon / carbon composite material having a layer structure in which a woven fabric or a non-woven fabric made of carbon fibers is laminated in a flat plate shape is formed. Steps and
A step of carving an annular molded body having a circumferential angle of less than 360 degrees from a flat carbon / carbon composite material or a precursor of a carbon / carbon composite material.
Steps to spirally shape an annular molded body,
The step of firing the shaped spiral annular molded body,
A method for manufacturing a spiral annular spring element having a structure composed of the above.

Further, in the invention according to the fourth aspect, in the method for manufacturing a spiral annular spring element according to the third aspect, the spiral annular spring element having a configuration in which the firing temperature in the firing step is 1000 ° C. to 3000 ° C. It was used as a method for manufacturing a spring element.

Further, in the invention according to the fifth aspect, in the method for manufacturing a spiral annular spring element according to the third or fourth aspect, in the firing step, firing is performed while maintaining the shape of the spiral annular molded body. This is a method for manufacturing a spiral annular spring element having the above configuration.

In the present invention, as a result of using a spring element made of a carbon / carbon composite material having the above-mentioned structure, it has become possible to provide a spring element that can be repeatedly used even in a high temperature environment exceeding 1000 ° C.
Further, in the spiral annular spring element having a layer structure in which carbon fiber non-woven fabric is laminated in parallel with the surface facing the central axis direction of the spring element, the torsional rigidity can be dramatically improved. It has become possible to provide a spring element having high torsional rigidity that can support a large load.
Further, according to the method for manufacturing a spiral annular spring element according to the present invention, since an expensive manufacturing jig is not required and cutting processing is easy, mass production is easy and cost reduction is achieved. Is now possible.

FIG. 1 shows a typical example of a spring element made of a carbon / carbon composite material according to the present invention. FIG. 2 shows a typical manufacturing process of a spring element made of a carbon / carbon composite material according to the present invention.

Hereinafter, the spring element made of a carbon / carbon composite material 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 large as that of a conventional carbon material or 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 rigidity because it has a small specific gravity and a high strength and rigidity (elastic modulus).

The carbon / carbon composite material includes carbon fibers oriented in only one direction, carbon fibers oriented in two or multiple directions in a plane, carbon fibers oriented in three directions three-dimensionally, and carbon fibers ( In addition to those in which (short fibers) are randomly oriented in a plane and carbon fibers (short fibers) are arranged in a three-dimensional manner, 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 (prepreg-shaped intermediate material) composed of a binder has been developed.

FIG. 1 shows a typical example of the spring element 1 made of a carbon / carbon composite material according to the present invention. The spring element 1 has a spiral annular shape composed of a spiral main body portion 11, one end side 12, and the other end side 13. Here, the spiral annular shape means a state in which the main body portion 11 spirally extends from one end side 12 to the other end side 13 of the spring element 1, as shown in FIG. Further, the inscribed angle from one end side 12 to the other end side 13 of the spring element 1 is less than 360 degrees, and a slit 14 is formed between the one end side 12 and the other end side 13.

The cross-sectional dimensions (w, b), outer diameter (D), and height (H) of the wire of the spring element 1 (see FIG. 1 for the notation of each dimension) are the load and the amount of deflection in which the spring element 1 is used. Determined by. Note that FIG. 1 shows that the wire of the spring element 1 has a rectangular cross-sectional shape, but the present invention is not limited to this.

The spring element 1 according to the present invention is composed of a two-dimensional carbon / carbon composite material (meaning a carbon / carbon composite material in which carbon fibers as reinforcing fibers are oriented in a plane), and the spring element 1 It has a layer structure laminated in parallel with the surface facing the central axis direction.
Here, "having a layer structure laminated in parallel with the surface of the spring element 1 facing the central axis direction" means the central axis direction of the spring element 1 shown in FIG. 1 (X direction in FIG. 1). It means that it has a layer structure laminated in parallel along the a1 surface (upper side surface in the front view of FIG. 1) and the a2 surface (lower side surface in the front view of FIG. 1) which are the surfaces facing the above. It is a thing.

As the carbon fiber used for each layer of the two-dimensional carbon / carbon composite material in the present invention, various forms can be used. For example, a sheet in which carbon fibers are aligned in one direction and oriented at different orientation angles (angle ply sheet), a woven fabric woven with a carbon fiber bundle, and short fibrous carbon fibers are randomly arranged in a paper shape. An oriented non-woven fabric can be used.

Next, an embodiment as an example of a method for manufacturing a spring element 1 made of a carbon / carbon composite material according to the present invention will be described.
The manufacturing method described here is a manufacturing method using a carbon fiber non-woven fabric, and is a sheet-like intermediate material composed of short fibrous carbon fibers, a binder pitch powder, coke powder, and a binder (a sheet-like intermediate material). Although a prepreg-like intermediate material) is used, the method for manufacturing the spring element 1 made of a carbon / carbon composite material according to the present invention is not limited to this.

The sheet-like intermediate material (prepreg-like intermediate material) for producing the carbon / carbon composite material used in the present embodiment is composed of short fibrous carbon fiber, binder pitch powder, coke powder, and binder. It is configured.

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, preferably having a length of 1 to 50 mm, and even more preferably having a length of 1 to 25 mm.

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 even more preferable.

Further, 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 fiber. 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.

As the dispersion liquid to be added to the mixture of the binder pitch powder, the coke powder, and the binder, an organic solvent such as alcohol or water can be used. 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 (prepreg-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 blending 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 papermaking.

In the sheet-like intermediate material (prepreg-like intermediate material) thus obtained, the short fibrous carbon fibers are 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 the spring element 1 made of a carbon / carbon composite material by using the sheet-shaped intermediate material (prepreg-shaped intermediate material) described above will be described.
FIG. 2 shows a flowchart of a process for manufacturing a spring element 1 made of a carbon / carbon composite material.

In step 101 of forming a flat plate-shaped carbon / carbon composite material or a precursor of a carbon / carbon composite material, when a sheet-shaped intermediate material (prepreg-shaped intermediate material) is used, it is manufactured through the above-mentioned steps. A plurality of sheet-shaped intermediate materials (prepreg-shaped intermediate materials) are laminated, and pressurized and heated using a hot press or the like. At this time, it is desirable that the heating temperature is higher than the temperature at which the binder pitch powder is softened and further caulked.

Further, the pressure to pressurize is appropriately set so that the laminated sheets of the sheet-shaped intermediate material (prepreg-shaped intermediate material) are in close contact with each other without being washed away when the binder pitch powder is softened, and a dense molded product can be obtained. NS.

In step 101 of forming the flat plate-shaped carbon / carbon composite material or the precursor of the carbon / carbon composite material, the binder pitch powder is softened and further heat-treated to a temperature higher than the caulking temperature, and then the obtained flat plate is obtained. The carbonization treatment and the graphitization treatment may be performed, and further, the pitch impregnation treatment may be performed in the intermediate stage of each treatment, and the carbonization treatment and the graphitization treatment may be repeated a plurality of times.

Further, the precursor in step 101 for molding the flat plate-shaped carbon / carbon composite material or the precursor of the carbon / carbon composite material adopts, for example, a process of producing the flat plate-shaped carbon / carbon composite material by the resincher method. In this case, it is intended to include a molded product (flat plate) at the stage where the resin which is the matrix material is cured.

Next, in step 102 of carving out the annular molded body, a circle having a slit as shown in FIG. 1 is obtained from the flat plate-shaped carbon / carbon composite material or the precursor of the carbon / carbon composite material obtained in step 101. The annular molded body is machined out. At this time, the presence of the slit 14 forms an annular molded body having a circumferential angle of less than 360 degrees.
The cross-sectional shape of the annular molded body is rectangular, but the cross-sectional shape is not limited to this, and a chamfered portion or a rounded portion may be provided at the corner portion.

Next, in step 103 in which the annular molded body is formed into a spiral shape, the annular molded body obtained in step 102 of carving out the annular molded body is subjected to the end faces of one end side 12 and the other end side 13. Is deformed by applying an external force so as to be separated from the spring element 1 in the central axis direction (X direction in FIG. 1), and the annular molded body is held by an appropriate jig while maintaining this deformed state. As a result, the annular molded body is shaped into a spiral shape as shown in FIG.

Next, in step 104 of firing the shaped spiral annular molded body, the spirally shaped annular molded body is fired in step 103. The firing temperature is preferably higher than the environmental temperature at which the spring element 1 is used, and it is particularly desirable to fire at 1000 ° C. to 3000 ° C.

Further, in step 104 of firing the shaped spiral annular molded body, in order to form an appropriate spiral shape, the shape of the spiral annular molded body can be fired while being held by an appropriate jig. desirable.

The torsional rigidity and shear strength of the spring element 1 manufactured by the manufacturing process using the sheet-shaped intermediate material (prepreg-shaped intermediate material) using the non-woven fabric described here are determined.
Torsional rigidity 4560 N ・ cm ²
Shear strength 54.6 MPa
It is manufactured by a process similar to the manufacturing process described here, using preformed yarn, which is a unidirectional reinforcing material, and using a two-dimensional reinforced carbon / carbon composite material that is alternately laminated at 0 ° / 90 °. The torsional rigidity and shear strength of the spring element 1 are
Torsional rigidity 997 N ・ cm ²
Shear strength 13.7 MPa
Met. It should be noted that these values represent the average values of the five data, and the torsional rigidity is defined by the following equation.
Torsional stiffness = Torsional modulus x moment of inertia of area The shear strength shown here indicates the value obtained by applying a shear load to a washer-shaped test piece.

1 Spring element 11 Main body 12 One end side 13 The other end side 14 Slit

Claims (4)

A spiral annular spring element, the spring element, Ri consists 2D carbon / carbon composite material having a layer structure that is stacked parallel to the surface facing the central axis of the spring element, the two-dimensional The carbon / carbon composite material is a spiral annular spring element having a layer structure in which carbon fiber non-woven fabrics are laminated in parallel with a surface of the spring element facing the central axis direction. A method for manufacturing a spiral annular spring element.
A sheet in which carbon fibers are oriented in one direction, or a flat carbon / carbon composite material or a precursor of a carbon / carbon composite material having a layer structure in which a woven fabric or a non-woven fabric made of carbon fibers is laminated in a flat plate shape is formed. Steps and
A step of carving an annular molded body having a circumferential angle of less than 360 degrees from a flat carbon / carbon composite material or a precursor of a carbon / carbon composite material.
Steps to spirally shape the annular molded body,
The step of firing the shaped spiral annular molded body and
A method for manufacturing a spiral annular spring element, which comprises. In the method for manufacturing a spiral annular spring element according to claim 2.
A method for manufacturing a spiral annular spring element, wherein the firing temperature in the firing step is 1000 ° C. to 3000 ° C. In the method for manufacturing a spiral annular spring element according to claim 2 or 3.
The firing step is a method for manufacturing a spiral annular spring element, which comprises firing while maintaining the shape of the spiral annular molded body.

Images