阅读说明：本技术 碳/碳复合材料弹簧元件及其制造方法 (Carbon/carbon composite spring element and method for producing same ) 是由 橘正晴 龟崎昭雄 松村和 于 2018-05-31 设计创作，主要内容包括：[问题]为了提供即使在超过1000℃的高温环境中也可以重复使用,具有使得能够支撑大负荷的高的扭转刚度,并且可以用作弹簧垫圈的弹簧元件。[方案]这种螺旋环形形状的弹簧元件配置成包含具有堆叠的层结构的二维碳/碳复合材料,其中层沿着所述弹簧元件的中心轴线方向堆叠。([ problem ] to provide a spring element which can be reused even in a high-temperature environment exceeding 1000 ℃, has a high torsional rigidity that enables a large load to be supported, and can be used as a spring washer. This spiral ring-shaped spring element is configured to include a two-dimensional carbon/carbon composite material having a stacked layer structure in which layers are stacked in a central axis direction of the spring element.)

1. A spring element having a helical and an annular shape,

wherein the spring element is made of a two-dimensional carbon/carbon composite material having a layer structure with layers laminated in parallel with a surface of the spring element facing in a direction of a central axis of the spring element.

2. Spring element with a spiral and a ring shape according to claim 1,

wherein the two-dimensional carbon/carbon composite has a layer structure having a layer of a carbon fiber nonwoven fabric laminated in parallel with a surface of the spring element facing in a direction of a central axis of the spring element.

3. A method for manufacturing a spring element having a helical and toroidal shape, comprising:

a step for forming a sheet of a carbon/carbon composite or a precast sheet of a carbon/carbon composite having a layer structure constructed by laminating a unidirectional carbon fiber sheet, a carbon fiber woven cloth, or a carbon fiber non-woven fabric,

a step for cutting out an element having a ring shape from the sheet or the prefabricated sheet of the carbon/carbon composite, wherein a central angle of the element having a ring shape is less than 360 degrees,

a step for forming the element having the annular shape into a spiral shape, and

a step for heat-treating the element having the spiral and annular shape.

4. Method for manufacturing a spring element having a spiral and a ring shape according to claim 3,

wherein the temperature of the heat treatment ranges from 1000 ℃ to 3000 ℃.

5. Method for manufacturing a spring element having a spiral and a ring shape according to claim 3 or 4,

wherein the step for heat-treating the element having the spiral and annular shape is characterized by the step of heat-treating the element while maintaining the shape of the element having the spiral and annular shape.

Technical Field

The present invention relates to a spring element made of a carbon/carbon composite material that can exert its properties particularly in a high-temperature environment. In particular, the present invention relates to a spring element that can be used as a spring washer in a high temperature environment and a method of manufacturing the same.

Background

Spring elements that can be used in spring washers are used as mechanical components in a variety of machines, devices, and mechanisms. Spring elements are nowadays a necessary and important component in the field of domestic products, industrial products and the like.

Typically, spring washers are generally made of metallic materials such as stainless steel, low alloy steel, tool steel, and titanium alloys.

However, metal spring washers have poor heat resistance, and thus they cannot exhibit sufficient spring characteristics in a high-temperature environment. Therefore, the metal spring washer cannot be used or cannot be used for a long time in a high-temperature environment.

For example, even if the spring washer is made of a heat-resistant alloy, the strength and deformation of the spring washer are significantly reduced and increased, respectively, and the subsidence resistance of the spring washer is also significantly reduced in a high-temperature environment exceeding 400 ℃. Therefore, even spring washers made of heat resistant alloys cannot be used in such high temperature environments.

When the spring washer is used in a high temperature environment exceeding 400 ℃, a spring washer made of a super heat-resistant alloy such as inconel alloy (inconel alloy), hastelloy alloy (hastelloy alloy), and the like may be used.

However, even spring washers made of super heat resistant alloys have their strength significantly reduced, their deformation significantly increased, and their subsidence resistance significantly reduced in a high temperature environment exceeding 700 ℃. Therefore, they cannot be used as springs in such high temperature environments.

Further, the spring washer may be made of ceramics such as silicon nitride and zirconia instead of inconel and hastelloy and the like. However, spring washers made of ceramics may be broken when they are repeatedly used in a high temperature environment due to their inherently low toughness and low thermal shock resistance. Further, in a high temperature environment exceeding 500 to 1000 ℃, spring washers made of ceramics may be broken due to their reduced strength.

In order to solve the problems described in the above paragraphs, a spring washer made of a carbon/carbon composite (also referred to as "C/C composite") is disclosed (see patent document 1).

Carbon/carbon composites ("C/C composites") are fiber-reinforced composites formed by hardening carbon fibers as reinforcing fibers with a graphite or carbon matrix. Since the strength and modulus of carbon/carbon composites are several times that of conventional carbon or graphite materials, and they have excellent heat resistance, wear resistance, and toughness, carbon/carbon composites are used for many parts, such as nose caps (nose caps) and wing leading edges of space shuttles; braking systems for airplanes, racing cars, new line vehicles, and large heavy trucks; internal structural members, trays and heaters of the heat treatment furnace; forks for processing products used in furnaces for the production of semiconductors and solar cells; and a high temperature fixture for metal processing.

The spring washer made of a carbon/carbon composite material disclosed in patent document 1 is produced by the following production method:

(1) the strength is more than 200Kg/mm²(1.96GPa) and a tensile modulus of greater than 24000Kg/mm²Strand-like (strand-like) prepreg or sleeve-like braided wire prepreg of carbon fiber (235.2GPa) is wound in a spiral groove formed at the outer surface of a cylindrical jig and semi-hardened by heat treatment;

(2) then, the semi-hardened and coil-shaped molded body is removed from the cylindrical jig and completely hardened by further heating.

(3) Then carbonizing the coil-shaped molded body by further heating and, if necessary, impregnating the coil-shaped molded body with molten pitch and then graphitizing it by heat treatment to produce a carbon/carbon composite having the coil-shaped molded body; and

(4) further, the spring washer made of the carbon/carbon composite material is completed by cutting the coil-shaped molded body into a single turn.

Since the spring washer made of the carbon/carbon composite material disclosed in patent document 1 is produced by the above-described production method, the carbon fiber, which is a long short fiber, extends along a spiral line or extends spirally along a spiral line. Thus, carbon/carbon composite spring washers have a strength and modulus that makes them useful as spring washers. However, they have too low a torsional stiffness to support a large load as a spring washer (spring washers require high torsional stiffness characteristics). Therefore, the carbon/carbon composite spring washer disclosed in patent document 1 cannot exert its sufficient capacity.

Further, with the spring washer made of carbon/carbon composite material disclosed in patent document 1, since the above-described manufacturing method is adopted, a different jig having a spiral groove is required for each spring washer having a different diameter. Further, since the spring washer is cut into a single turn from the coil-shaped molded body, it is difficult to mass-produce the spring washer made of the carbon/carbon composite material, and therefore, their production cost becomes high.

Disclosure of Invention

Problems to be solved by the invention

The present invention has been conceived based on the above technical background. The problem to be solved by the present invention is to provide a spring element which can be reused even in a high temperature environment exceeding 1000 ℃, has a high torsional rigidity to be able to support a large load, and can be used as a spring washer.

Means for solving the problems

In order to solve the above problems, in a first aspect of the present invention, the present invention includes the following:

a spring element having a helical and an annular shape,

wherein the spring element is made of a two-dimensional carbon/carbon composite material having a layer structure with layers laminated in parallel with a surface of the spring element facing in the direction of the central axis of the spring element.

In a second aspect of the invention, the invention comprises the following:

the spring element of the first aspect of the invention having a helical and annular shape,

wherein the two-dimensional carbon/carbon composite has a layer structure with a layer of carbon fiber nonwoven fabric laminated parallel to the surface of the spring element facing in the direction of the central axis of the spring element.

In a third aspect of the invention, the invention comprises the following:

a method for manufacturing a spring element having a helical and an annular shape, comprising:

a step for forming a carbon/carbon composite panel or a carbon/carbon composite prefabricated panel having a layer structure constructed by laminating a unidirectional carbon fiber sheet, a carbon fiber woven cloth, or a carbon fiber non-woven fabric,

a step for cutting out an element having a ring shape from a plate or a prefabricated plate of a carbon/carbon composite, wherein a central angle of the element having a ring shape is less than 360 degrees,

a step for forming the element having the annular shape into a spiral shape, and

a step for heat-treating the element having the spiral and annular shape.

In a fourth aspect of the invention, the invention comprises the following:

the method for manufacturing a spring element having a spiral and annular shape of the third aspect of the invention,

wherein the temperature of the heat treatment ranges from 1000 ℃ to 3000 ℃.

In a fifth aspect of the invention, the invention comprises the following:

the method for manufacturing a spring element having a spiral and annular shape of the third or fourth aspect of the invention,

wherein the step for heat-treating the member having the spiral and annular shapes is replaced with a step for heat-treating the member having the spiral and annular shapes while maintaining the shape of the member.

Effects of the invention

In the present invention, since the spring element is made of the carbon/carbon composite material having the above technical features, it is possible to provide a spring element that can be repeatedly used in a high temperature environment exceeding 1000 ℃.

Furthermore, the torsional stiffness of the spring element can be significantly improved for: the spring element shown has a spiral and annular shape with a layer structure containing layers of carbon fiber nonwoven fabric laminated parallel to the surface of the spring element facing in the direction of the central axis of the spring element. Therefore, a spring element having a high torsional rigidity that can support a large load can be provided.

Further, by using the method for manufacturing a spring element having a coil and loop shape of the present invention, since there is no need to use an expensive jig for manufacturing the spring element and the cutting operation thereof is easy, mass production of the spring element and reduction in cost become possible.

Drawings

Fig. 1 shows a typical example of a spring element made of a carbon/carbon composite material of the present invention.

Fig. 2 shows a typical example of a manufacturing method of a spring element made of a carbon/carbon composite material of the present invention.

Detailed Description

Next, the spring element made of a carbon/carbon composite material of the present invention is explained.

Carbon/carbon composites ("C/C composites") are fiber-reinforced composites formed by hardening carbon fibers as reinforcing fibers with graphite or a carbon matrix.

The carbon/carbon composite material has strength and modulus several times higher than those of conventional materials, and also has excellent heat resistance, wear resistance and toughness, as compared to conventional carbon or graphite materials.

In addition, since the carbon/carbon composite material has low density, high strength, and high rigidity (elastic modulus), it is also known as a material having high specific strength and high specific rigidity.

In general, carbon/carbon composites having carbon fibers in various orientations have been produced such that the carbon fibers are oriented unidirectionally, bidirectionally, or multi-directionally in two dimensions and three-directionally in three dimensions, and further such that the carbon fibers (short length fibers) are oriented in random fashion in two or three dimensions and such that the carbon fibers are oriented in various patterns.

In addition, various manufacturing methods of carbon/carbon composites have been developed, such as a resin-carbonization (resin-char) method, a CVD method, a method using a preformed yarn, and a method using a preformed sheet (prepreg sheet) composed of short-length carbon fibers, a powder of binder pitch, a powder of coke, and a binder.

Fig. 1 shows a typical example of a spring element 1 made of a carbon/carbon composite material according to the invention.

The spring element is constituted by a body 11 having a spiral and annular shape, defined as the body 11 extending helically from one end 12 to the other end 13, one end 12 of the body 11 and the other end 13 of the body 11.

Further, the central angle from one end 12 to the other end 13 of the spring element 1 is less than 360 degrees, and the space between the one end 12 and the other end 13 of the spring element 1 forms a slit 14.

The dimensions (w, b), diameter (D) and height (H) (the symbols are shown in fig. 1) in the cross section of the main body 11 of the spring element 1 are determined based on the load conditions acting on the spring element 1 and the deflection of the spring element 1.

In fig. 1, although the shape of the cross section of the main body 11 of the spring element 1 is shown as a rectangle, the shape of the cross section of the main body 11 is not limited to a rectangle.

The spring element 1 of the present invention is composed of a two-dimensional (carbon fibers as reinforcing fibers are oriented in two dimensions) carbon/carbon composite material, and has a layer structure including layers laminated in parallel with the surface of the spring element 1 facing the direction of the central axis of the spring element 1.

In the above paragraph, "a layer structure including a layer laminated in parallel with a surface of the spring element 1 facing in the direction of the central axis of the spring element 1" means that the layer structure is formed of a layer laminated in parallel with a surface "a 1" (upper surface in front view in fig. 1) and a surface "a 2" (lower surface in front view in fig. 1), the surface "a 1" and the surface "a 2" being surfaces facing in the direction of the central axis of the spring element 1 in fig. 1 (X direction in fig. 1).

In the layer of the two-dimensional carbon/carbon composite material of the present invention, various carbon fibers can be used. For example, the following materials may be used for the layers: angle-ply-laminated sheets (angle-ply-laminated sheets) formed by laminating sheets of unidirectionally oriented carbon fibers while changing the orientation, fabrics woven by using carbon strands, or carbon fiber nonwoven fabrics formed by orienting short-length carbon fibers in a random manner similar to paper.

Next, as an example, an embodiment of the method for manufacturing the spring element 1 made of a carbon/carbon composite material of the present invention is explained.

The manufacturing method described herein is a method using a carbon fiber nonwoven fabric. That is, this manufacturing method uses a preform sheet (prepreg sheet) composed of short-length carbon fibers, a powder of binder pitch, a powder of coke, and a binder. However, the method of the present invention for manufacturing the spring element 1 made of a carbon/carbon composite material is not limited to such a method.

The preform sheet (prepreg sheet) used in the method for manufacturing the spring element 1 made of carbon/carbon composite material is composed of short-length carbon fibers, powder of binder pitch, powder of coke, and a binder.

In this embodiment, polyacrylonitrile-series carbon fibers, rayon-series carbon fibers, or pitch-series carbon fibers may be used as the carbon fibers. Furthermore, all types of carbon fibers that are heat treated for flame retardancy, carbonized or graphitized may be used.

The carbon fiber used in this embodiment is a short length fiber, carbon fiber of 1mm to 50mm in length is preferable, and carbon fiber of 1mm to 25mm in length is further preferable.

The powder of the binder pitch used in this embodiment is derived from petroleum and/or coal, and has heat softening characteristics. Their softening temperature is 60 to 320 ℃, quinoline insolubles are 0 to 80 wt%, and volatiles are 10 to 60 wt%. Furthermore, they may be made from petroleum and/or coal, having isotropic, potentially anisotropic, or anisotropic properties.

The powder of binder pitch is used to bind the reinforcing fibers (carbon fibers), and the powder of coke serves as an aggregate (explained below). The powder of the binder pitch preferably has an average particle diameter of 0.5 to 60 micrometers, and more preferably has an average particle diameter of 3 to 20 micrometers.

The coke fines used in this embodiment are derived from petroleum and/or coal and have no heat softening characteristics. They act as aggregates and have no softening temperature. The volatiles are preferably less than 10 wt% and more preferably less than 2 wt% volatiles.

Any type of powder of petroleum or coal derived coke may be used in this embodiment. The average particle diameter of the powder of the coke is preferably 0.5 to 30 micrometers, and further preferably 1 to 20 micrometers.

Although the composite ratio of the powder of the binder pitch derived from petroleum and/or coal and having heat softening property to the powder of the coke derived from petroleum and/or coal and having no heat softening property is not limited to a specific value, the composite weight ratio of [ powder of binder pitch ]/[ powder of coke ] is preferably 90/10 to 10/90, and it is further preferable that the ratio is 70/30 to 30/70.

The binder used in this embodiment serves to bind the powder of binder pitch with the powder of coke, and further to bind the carbon fibers with the composite composed of the powder of binder pitch, the powder of coke, and the binder.

As the binder, a thickening stabilizer (starch binder composition) industrially used, for example, methylcellulose can be used. In addition, thickening stabilizers of natural origin and of chemical synthesis can be used as binders.

As the dispersion liquid added to the composite composed of the powder of the binder pitch, the powder of the coke, and the binder, an organic solvent such as alcohol, or water may be used.

Further, the volume carbon fiber content of the entire volume of the preform sheet is 5 to 70 vol%, preferably 20 to 60 vol%.

The preform sheet (prepreg sheet) of this embodiment is produced by the following method:

(1) a method of preparing a mixed solution by mixing a powder of a binder pitch, a powder of coke, a binder, and a dispersion liquid at a predetermined mixing ratio;

(2) a method of uniformly dispersing short-length carbon fibers in a mixed solution by putting predetermined amounts of the mixed solution and the short-length carbon fibers into a mixing tank and mixing them; and

(3) a papermaking process by pressure-feeding a mixed solution in which short-length carbon fibers are mixed and dispersed from a mixing tank to a paper machine is known.

In the preform sheet (prepreg sheet) produced by the above method, short-length carbon fibers are oriented in a random manner in the plane of the preform sheet, entangled with each other, and arranged in a nonwoven fabric state. Further, the continuous sheet of the nonwoven fabric composed of the short length carbon fibers and the powder of the binder pitch, the powder of the char, and the binder arranged around the short length carbon fibers has a predetermined tackiness by mixing the binder mixed in the solution.

Next, a method for manufacturing the spring element 1 by using the above-described preform sheet (prepreg sheet) will be described.

Fig. 2 shows a flow chart of a method for producing a spring element 1 made of a carbon/carbon composite material.

In step 101 of forming a panel of a carbon/carbon composite material or a prefabricated panel of a carbon/carbon composite material by using prefabricated sheets (prepreg sheets), a plurality of prefabricated sheets (prepreg sheets) produced by the above-described process are laminated, and pressurization and heating are performed by using a hot press or the like. When the laminate sheets are pressurized and heated, it is desirable to heat them up to a temperature greater than that at which the powder of binder pitch softens, and then to a temperature greater than the coking temperature of the binder pitch.

The pressure for pressing the laminated sheet is determined so that the powder of the binder pitch does not flow away from the preform sheet when softened, the preform sheet (prepreg sheet) adheres closely with its intermediate layer, and a dense molded body can be formed.

Further, in step 101 for forming a sheet of carbon/carbon composite or a prefabricated sheet of carbon/carbon composite, after heat-treating the laminated sheet to a temperature greater than a temperature at which the powder of binder pitch is softened, and then heating to a temperature greater than a coking temperature of the binder pitch, the sheet produced by the heat treatment may be carbonized, and further graphitized.

Further, an asphalt impregnation process may be added between each of the above-described processes, and the carbonization and graphitization processes may be repeated several times.

In step 101 for forming a sheet of a carbon/carbon composite or a preformed sheet of a carbon/carbon composite, the preformed sheet means, for example, a molded body including (the sheet of) a precursor used in a process for manufacturing the sheet of the carbon/carbon composite by a resin carbonization method, so that a resin as a matrix material is cured.

Next, in step 102 for cutting the molded body having the annular shape, the molded body having the annular shape and the slits as shown in fig. 1 is cut out from the sheet of the carbon/carbon composite material or the prefabricated sheet of the carbon/carbon composite material produced through step 101 by a machining process.

Since the cut molded body has the slit 14, it is possible to form the molded body having a central angle of less than 360 degrees and a ring shape.

Although the shape of the cross section of the molded body having the annular shape is a rectangle, it is not limited to this shape. Cross-sectional shapes having chamfered or rounded corners may be used.

Next, in step 103 for spirally forming the molded body having the annular shape, the molded body having the annular shape produced in step 102 is held by a jig while being deformed by an external force, so that the end surfaces of the one end 12 and the other end 13 are separated from each other in the central axis direction (X direction in fig. 1) of the spring element 1 while the deformation of the molded body is maintained.

By the method in step 103, a molded body having a ring shape as shown in fig. 1 is spirally formed.

Next, in step 104 for heat-treating the formed molded body having the spiral and annular shapes, the molded body having the annular shape spirally formed in step 103 is heat-treated. The preferred temperature for the heat treatment of the molded body is a temperature which is higher than the ambient temperature in which the spring element 1 is used. It is particularly desirable to heat treat the molded body at a temperature of 1000 ℃ to 3000 ℃.

In step 104 for heat-treating the shaped molded body having the spiral and annular shape, in order to form the spiral and annular shape of the molded body, it is desirable to heat-treat the molded body while holding the molded body by a jig.

The torsional rigidity and shear strength of the spring element 1 produced by the manufacturing method using the above-described preform sheet of nonwoven fabric (prepreg sheet) are as follows:

torsional rigidity 4560N cm²

Shear strength 54.6MPa

The torsional rigidity and shear strength of the spring element 1 produced by the same manufacturing method as described above and using the two-dimensional carbon/carbon composite material having the layer structure in which layers of the unidirectionally reinforcing preformed yarns are alternately laminated in the 0-degree and 90-degree directions are as follows:

torsional rigidity 997N cm²

Shear strength 13.7MPa

These values are the average of 5 test data and the torsional stiffness is defined by the following equation:

torsional stiffness-torsional modulus multiplied by area polar moment of inertia

Further, the above shear strength is obtained by loading a shear force on a test piece having a washer shape.

Description of the symbols

1 spring element

11 main body

12 one end of

13 another end

14 slit