This disclosure relates to a layered carbon-fiber product and a preform used for fiber reinforced plastics, or processes for producing these, and specifically relates to an improvement technology of the trimming the layered carbon-fiber product or the preform.
Recently, fiber reinforced plastics made with carbon fibers are getting more often used to achieve a weight reduction of airplanes and cars. Particularly, a fiber reinforced plastic which is made with carbon-fiber bundles consisting of a plurality of carbon fibers arranged in a single direction has a lot of advantages in a specific rigidity and a specific strength relative to metal materials and therefore is applied to various component parts.
For forming methods of the fiber reinforced plastic made with unidirectional carbon fiber bundles, suggested are various methods, such as a prepreg/autoclave forming method, an RTM (Resin Transfer Molding) forming method, RFI (Resin Film Infusion) forming method or forming methods derived from them. Particularly, RTM forming method has attracted public attentions because it makes it possible to prepare a fiber reinforced plastic having a complicated shape if matrix resin is impregnated and is set in a preform which has been formed so that the fabrics are fixed to each other while keeping its desirable shape with a layered carbon-fiber product which has been made with layered fabrics such as carbon fibers shown in
However, because carbon fibers have some rigidity as well as very small diameter around 10 μm, the layered carbon-fiber product or the preform has to be squashed in the part to be cut when the layered carbon-fiber product or the preform is cut by contacting blades, as shown in
Such preforms may cause a mismatch against the shape of cavity of a forming die on which the preform is placed. If the preform is larger than the forming die, it may be cut to trim its shape to fit the forming die, or the preform which is larger than the forming die may be as-is placed and formed in the forming die. In the latter case, carbon fibers might be included in the burr of formed fiber reinforced plastics, to cause a trouble that the cumbersome burring process is required.
On the other hand, if the preform is smaller than, a resin-only part (resin-rich part) is formed in a gap toward the forming die, so that the process of burying the carbon fiber before pouring matrix resin is further required. In addition, even if the preform almost matches the forming die in a shape, it is difficult to completely suppress the mismatch because edge faces may be frayed while transporting the preform to the forming die.
Thus, because of difficulty of processing the carbon fiber, great manpower has been required to position the preform relative to the forming die, as well as a burring process after forming.
For such carbon fibers which is easy to fray, suggested are methods such as a method to sew the edge part of the preform and another method to apply resin material of bonds, etc., to the edge face of the preform to be cut. According to the method to sew the edge part of the pre-form, slightly inner side from the edge face of the preform is actually sewn. Therefore, cutting the edge face could not completely prevent the carbon fiber from fraying and might cause a secondary fray of the sewing yarn itself. According to the method to apply resin material of bonds, etc., impurities might adhere while applying the resin material, and defects such as strength poverty of the formed fiber reinforced plastic and crack initiation, might be caused by entraining air in the resin material. These methods are not efficient enough from the viewpoint that the preform to be cut has to be subject to an additional treatment though having some advantage.
JP 2004-288489 A and JP 2005-297547 A disclose a method to prepare a sheet-shaped product from short carbon fibers (about 3-20 mm) with phenolic resin, etc., as a technology of binding carbon fibers. They disclose that such a sheet-shaped product is prepared by randomly dispersing the short carbon fibers in a two-dimensional plane before burning in an inert atmosphere together with phenolic resin at high temperature more than approximately 2,000° C. The sheet-shaped product disclosed in these documents is suitably used for producing carbon fiber electrodes. The sheet-shaped product is not impregnated with additional matrix resin before its use. Further, burning at high temperature of more than approximately 2,000° C. makes the short carbon fibers themselves carbonized, and therefore the elastic modulus and the strength which the short carbon fibers themselves have had cannot be maintained.
JP 2008-248457 A and JP 2008-163535 A disclose a method to prepare a carbon fiber complex on a three dimension network made from prong-shaped graphene layers including metal fine particles or metal carbide particles by heating mixed hydrocarbon gases made of hydrocarbon up to over 800° C. together with catalytic metal fine particles, as another method to bind carbon fibers to each other. However, because the metal fine particles are included as a catalyst in these method, produced fiber reinforced plastics might become comparatively heavy, and heating the carbon fibers up to over 800° C. again might make some parts carbonized so that a desirable elastic modulus and a desirable strength are not given.
JP '489, JP '547, JP '457 and JP '535 disclose technologies for forming three dimension network with carbon binding parts to carbon fibers which are dispersed in a single yarn scale. Therefore, it may not be preferable that they are applied for binding unidirectional carbon-fiber bundles composing a fabric, from a viewpoint of impregnation characteristics of resin: The reason is the following.
It is generally known that resin impregnation into unidirectional carbon-fiber bundles makes the resin permeate by capillary action along the periphery (peripheral surface) of carbon fibers. If there is a binding part as an intersection of three dimension network on a surface of the carbon-fiber bundle, the resin would permeate as circumventing the binding part. Namely, the reason is because the binding part might cause obstruction to the flow as making a difference of the permeation velocity or the permeation distance of the resin between the binding part and the periphery without a binding part and might generate defects such as microvoids and uncompleted impregnation.
JP 3685364 B discloses a method to form a coating layer made of carbon on surfaces of graphite particles after treating the graphite particles with surfactant. This is merely a coating technology for spherical carbon, and does not disclose any technical idea to bind a carbon fiber or a carbon-fiber bundle to each other.
JP 63-74960 A discloses vitreous carbon-coated carbon material. It relates to a technology to produce wafers with carbon material by chemical vapor deposition (CVD), and concretely relates to a technology to form vitreous carbon coat, where the solution prepared with organic polymer such as heated polyvinyl chloride, dissolved in solvent is applied to the surface of carbon material. In JP '960, the organic polymer other than the carbon material as a matrix has to be used to form the coat. Although it aims to form the coating without crack and pinhole on the surface of the carbon material, it does not disclose any method to coat random edge faces such as ones of carbon-fiber bundles.
JP 10-25565 A discloses a method to prepare a hard film by arc ion plating. This method relates to a technology to form a film which is made by applying voltage to a carbon source on the matrix under low-vacuum condition. The hard film is a carbon network of amorphous carbon which is superior in surface smoothness. Such a method to prepare a hard film cannot be applied to forming a film in air. Neither a method to cut the matrix nor a method to form random edge faces such as ones of carbon fiber bundles, are disclosed.
JP 53-108089 A discloses a method to manufacture vapor phase pyrolytic carbon, where the gas which contains halogenated hydrocarbon is pyrolized at a temperature over 400° C. so that carbon is precipitated. In such a method, the pyrolytic carbon made from heated halogenated hydrocarbon in inert gas is filled in the space among fibers of fabric products made from carbon fibers of matrix to manufacture a carbon fiber-carbon composite. It discloses neither the necessity to make the pyrolytic carbon for binding from the halogenated hydrocarbon, nor a concrete method to coat random edge faces such as ones of carbon-fiber bundles.
JP 10-45474 A discloses a method where pyrolytic carbon coated graphite material is subjected to a heat treatment at 1500-2500° C. in a halogen gas atmosphere. It discloses neither the necessity to subject the graphite material other than the matrix to a heat treatment in the halogen gas atmosphere, nor a concrete method to coat random edge faces such as ones of carbon-fiber bundles, although it discloses an advantage of close linear expansion coefficient between the coating material and the carbon fiber reinforced carbon material.
Thus, it has been necessary to establish a method to prevent carbon fibers from fraying at edge faces of a preform and to form desirable shapes easily, when the preform made from unidirectional carbon-fiber bundles is disposed in a forming die.
Accordingly, it could be helpful to provide a layered carbon-fiber product, a preform and processes for producing these, where the edge face of the layered carbon-fiber product or the preform can be easily processed and the carbon fibers are prevented from fraying at the edge face to achieve trimming process with great accuracy.
We thus provide a layered carbon-fiber product, wherein a layered carbon-fiber product obtained by layering one or more sheets of carbon-fiber fabrics each prepared using one or more carbon-fiber bundles each comprising a plurality of carbon fibers arranged in a single direction, characterized in that at least a part of a surface and/or an edge face of the layered carbon-fiber product is constituted of a graphitized part and that the graphitized part exhibits a Raman spectrum in which an intensity ratio of a D band to a G band is 0.3 or less. The intensity ratio of the D band to the G band is calculated by the following formula:
(Intensity ratio)=(D-band intensity/G-band intensity).
It is preferable that the graphitized part is formed on an edge face of the layered carbon-fiber product.
It is also preferable that adjacent carbon fibers are bound to each other in the graphitized part, and is further preferable that the number of the bound carbon fibers is at least 15.
Further, it is preferable that the graphitized part is made of a graphite film having a film thickness equal or less than 0.1 mm, and is also preferable that the graphite film has a linear mark on a surface thereof.
It is preferable that the graphitized part has a graphitized cut edge face which is formed on an edge surface cut by radiating a beam.
Furthermore, it is preferable that a longitudinal cut surface of the carbon fiber exhibits the Raman spectrum in which an intensity ratio of a D band to a G band (D-band intensity/G-band intensity) is 0.8 or more, and 1.4 or less.
It is preferable that the carbon fiber includes at least a long fiber of a PAN series carbon fiber.
We also provide a preform made with the layered carbon-fiber product, characterized in that a binding resin material is laid on a surface of the carbon-fiber fabric and the carbon-fiber fabrics adjacent are bound to each other.
We further provide a fiber reinforced plastic which is made by impregnating the preform with a matrix resin to be hardened.
We still further provide a process for producing a layered carbon-fiber product which is obtained by layering one or more sheets of carbon-fiber fabrics each prepared using one or more carbon-fiber bundles each comprising a plurality of carbon fibers arranged in a single direction, characterized in that: a surface and/or an edge face of the layered carbon-fiber product is graphitized by radiating a beam to the layered carbon-fiber product.
In the process, it is preferable that the beam is radiated to the layered carbon-fiber product to cut the layered carbon-fiber product into a predetermined shape and a cut surface is graphitized.
It is preferable that at least one of an energy density, an operation speed and a depth of focus is controlled in radiating the beam, and is also preferable that the beam is any of a spot laser and line laser.
Furthermore, our process produces a preform made with any of the layered carbon-fiber products, characterized in that a binding material is laid on a surface of the carbon-fiber fabric and a preform, in which the adjacent carbon-fiber fabrics are bound to each other, is graphitized by radiating any of the beams.
It is thus possible that layered carbon-fiber material products or the edge face of preforms arc easily processed, and a trimming process is achieved with high precision without fraying of carbon fibers at edge faces. Therefore, layered carbon-fiber products or preforms can be positioned in a forming die easily and accurately. If the positioning to the forming die is simplified and the burring work is omitted, the low cost and the short production time can be achieved by the reduced manpower. Further, crack generation can be prevented with hard graphite film on the edge part of the fiber reinforced plastic prepared by forming the preform. Furthermore, layered carbon-fiber products and preforms can be trimmed accurately in a short time with laser beam, etc., without using other materials such as carbon material and halogenated hydrocarbons.
Hereinafter, desirable examples will be explained as referring to figures.
Layered carbon-fiber product 20 as an example will be explained as referring to
a) is a schematic diagram showing an example of layered carbon-fiber product 20 of which at least a part of a surface and/or an edge face is graphitized and which represents characteristics of our product.
In
Regardless of the interposition of binding part 42, it is preferable that adjacent carbon fibers 1 are bound at graphitized part 40. Though a whole of graphitized part 40 is preferably formed uniformly, graphitized part 40 may not be easily formed in a region having a large void because carbon fibers 1 are eccentrically located in unidirectional carbon-fiber bundle 5.
It is more preferable that there is a region where the number of bound carbon fibers 1 is more than 15. To develop machine characteristics of a fiber reinforced plastic, it is preferable that carbon fibers 1 are close-packed and impregnated with resin. The volume fiber content in a fiber reinforced plastic is generally expressed as Vf. Vf is required to be around 55-65%, in a technical field of excellent machine characteristics aimed at airplanes or cars. The upper limit of Vf is regarded as around 70%, from a viewpoint of close packing. For example, in the case where carbon-fiber fabrics having a weight per unit area of 190 g/m2 are layered to satisfy the formula “Vf=70%”, it is preferable that carbon fibers 1 are bound so that the thickness is composed by at least 15 carbon fibers 1, which form unidirectional carbon-fiber bundle 5 and which have a diameter of 10 μm and a density of 1.8 g/cm3, and unidirectional carbon-fiber bundle 5 is restrained at least in a thickness direction.
The thickness can be calculated by the following formula:
(Weight per unit area)/(density)/(Vf)/10=(thickness) (mm).
a) is a schematic diagram showing B-B′ section which is exposed by cutting edge face 6 of unidirectional carbon-fiber bundle 5 in
As shown in
Even if graphite film 45 formed on edge part 6 of unidirectional carbon-fiber bundle 5 shown in
Thus, regardless of orientation of unidirectional carbon-fiber bundle 5, if graphitized part 40 is formed with graphite film 45 on the surface and/or edge face of layered carbon-fiber product 20, carbon fibers 1 can be formed by a predetermined dimension accuracy without fraying. Even if touched with fingers, graphite film 45 would not be exfoliated nor would carbon fibers 1 be frayed, so that the transportation work is made easy and repair work is not needed. Further, if graphitized part 40 is selectively formed at the edge part of layered carbon-fiber product 20, the inside of layered carbon-fiber product 20 is desirably made in a homogeneous form. The homogeneous form, for example, makes it possible that layered carbon-fiber product 20 is homogeneously impregnated with resin to generate fiber reinforced plastics.
On the other hand, if such graphite film 45 is not formed, fingers touched to unidirectional carbon-fiber bundle 5 would bend carbon fibers 1 or fray 50 flaring outwardly would be caused, as shown in
Hereinafter, the procedure to measure film thickness 46 will be explained.
Graphite films 45 are exfoliated and collected with something like tweezers from edge part 6 of unidirectional carbon-fiber bundle 5. Because collected graphite films 45 are fragile, cubes larger than 0.1 mm cube are selected to be determined as nipped by a double flat micrometer. The number of samples (N) is more or equal to 5, and the final value is calculated by averaging measurement values. In the case where graphite film 45 exists in a fiber reinforced plastic, the measurement can be achieved similarly by a micrometer after collecting graphite film 45 from a sample which has been burned to remove resin component by an electric furnace or of which resin component has been decomposed with concentrated nitric acid or concentrated sulfuric acid and removed by a residual washing (ASTM D 3171).
It is important that the intensity ratio of Raman spectrum of graphitized part 40 is in a predetermined range.
What is called “graphitization” is to be burned at a high temperature over 200° C., which is different from “carbonization” which means to be burned at a low temperature from 700° C. to 2000° C. As to graphitized graphite film 45 and graphitized carbon-fiber edge part 48, it is important that the intensity ratios calculated by the following formula from the peaks of G band and D band of the graphitized part are less than or equal to 0.3. More preferably, they are less than or equal to 0.2. Because the elastic modulus of carbon material becomes greater in a crystal orientation direction when further carbonized, the smaller intensity ratio is regarded as being the harder. In other words, graphitized graphite film 45 and graphitized carbon-fiber edge part 48 are supposed to be harder than the other parts which are not graphitized so that fray 50 of edge part 2 of carbon fiber 1 is prevented from maintaining its shape. Therefore, it is preferable that the intensity ratio is smaller, and in particular, is smaller than the intensity ratio of the raw carbon fiber.
(Intensity ratio)=(Intensity of D band)/(Intensity of G band)
As carbonfiber 1, it is preferable that a so-called “high strength” type of carbon fiber, which has been burned at a low temperature, is employed, from a viewpoint of energy saving for manufacturing relative to a high elastic type thereof. Further, it is preferable that carbon fiber 1 is a PAN series carbon fiber including a long fiber. Because the PAN series carbon fiber consists of a kind of component, it is easier to handle than a pitch series carbon fiber, and can be given a high strength at a lower temperature than a rayon series. What is called the “long fiber” is a continuous fiber, and is desirable because it can achieve high elastic modulus and high strength in fiber reinforced plastics of which reinforcing fibers take a burden.
As to carbon fiber 1 which is not graphitized, it is preferable that an intensity ratio of G band to D band of a Raman spectrum obtained by a laser Raman spectroscopy analysis is more than or equal to 0.8 and less than or equal to 1.4. The range which is defined by “more than or equal to 0.8 and less than or equal to 1.4” corresponds to a PAN series carbon fiber which has been burned at a temperature from 800-2000° C. It has not been graphitized. Therefore, the edge rigidity can be desirably improved by a graphitized part.
Next, desirable examples of preform 30 made with carbon-fiber fabric 10 will be explained. Preform 30 is layered carbon-fiber product 20 which has been made by layering carbon-fiber fabric 10 and is shaped and maintained in its shape. To maintain the shape, a method such as sewn product manufacturing, sewing carbon-fiber fabrics to each other by stitching, envelope unification of carbon fibers by needling carbon-fiber fabrics with a barbed needle, unification of carbon-fiber fabrics with tackifier resin and unification by heating carbon-fiber fabric 10 made by weaving thermoplastic resin fiber with carbon fiber 1, can be employed.
Particularly, it is preferable that preform 30 is manufactured by heating and cooling layered carbon-fiber product 20 made by layering carbon-fiber fabric 10 which has been applied with particulate tackifier resin which is easy to be maintained in the shape of preform 30 in a shaped condition as softening, bonding and solidifying the particulate tackifier resin. Further, it is preferable that the surface of carbon-fiber fabric 10 is applied with the particulate tackifier resin to not block the impregnation of matrix resin into the inside of unidirectional carbon-fiber bundle 5.
Next, a method to form graphitized part 40 on edge face 22 of layered carbon-fiber product 20 or preform 30 will be explained, as referring to preform 30 exemplified in
Among the above-described non-contact cutting method using the laser beam, preferable is a laser beam cutting method which can be used to cut in the air without vacuuming. A solid-state laser, a semiconductor-excited solid-state laser and a semiconductor laser which have higher densities than gas or liquid and which output greatly per unit volume are more preferable than X-ray laser of which wavelength is in the range of ultraviolet ray. However, an excimer laser which can be used to cut a bonding between molecules without thermally affecting the environment might be used at a high output desirably. Further, it is preferable that CW laser (Continuous Wave Laser), such as fiber laser and disk laser, which is excellent in cooling efficiency and which can continuously radiate, is employed as an oscillator of the solid-state laser or a diode-pumped solid-state laser. Both have little heat distortion and little deterioration of a solid crystal which have been caused in a solid-state laser such as YAG, and a continuous radiation can be performed. It is preferable that a laser beam which can radiate continuously is scanned because continuous graphite film 45 can be formed on a cut face and the fray of unidirectional carbon-fiber bundle 5. A mirror type and a fiber type are exemplified as a transmission method of the laser beam though not limited thereto. Further, in the case where a spot laser which radiates in spots does not sufficiently output, a line laser which transports spotted laser beams with a prism into a linear laser so that surface 21 and edge face 22 are desirably used to reform to graphitized part 40. Furthermore, it is preferable to use a galvano mirror when the output is not sufficient with the line laser.
Further, if the output of the laser beam is more or equal to 100 W and the converging diameter is less or equal to 100 μm, the energy density, which is obtained from the output and the converging diameter, can be set more or equal to 100/(π*500*500)≈1.2*10−4 (W/μm2). Such an amount of energy density would quickly heat carbon fiber 1 to a temperature required to be sublimed and cut desirably. It is more preferable that the energy density is more than or equal to 0.01 (W/μm2). It is practically preferable that the feeding speed of the laser beam is more than or equal to 0.1 m/min. It is preferable that the depth of focus is chosen appropriately by a subject work. To cut a heavy fabric as having a thickness of more than 2 mm, it is preferable that the depth of focus is from −1 mm to +1 mm relative to the surface of the work so that a hole is bored on the surface of the work in a short time and the laser beam is efficiently projected into the bored hole in a thickness direction.
The laser beam is broadened around the focus to narrow the focus. Therefore, if the focus is positioned at the lower surface of the work in a thickness direction, because a laser beam of which focus has not been sufficiently narrowed is radiated to the surface of the work, the cutting might not be performed at desirable speed. It is preferable that cutting is performed in an atmosphere containing more nitrogen than the air. When the laser beam is radiated in the air, carbon fibers might catch fire and deteriorate. Nitrogen can be supplied by a method to suck from a hose connected to a nitrogen cylinder to an radiation head of laser beam as blowing concentrically and a method to inject laterally from a nitrogen nozzle attached to the laser head, though not limited thereto.
By such a laser oscillator which can continuously radiate, carbon fiber 1 made of extremely thin fiber would hardly remain uncut. A heavy fabric having a thickness more or equal to 2 mm as a bulky fabric which is not stably formed such as unidirectional carbon-fiber bundle 5, carbon-fiber fabric 10, layered carbon-fiber product 20 and preform 30, and above all in particular, layered carbon-fiber product 20 made of dry carbon fiber 1 and preform 30 can be cut precisely. After cutting, carbon fiber 1 does not tend to fall off during separating chips from preform 31 at the product side, rapid process can be performed even if applied to a complicated shape because a postprocessing is not necessary. For example, surround of preform 30 can be cut to form a complicated shape such as three-dimensional shape of a car bonnet, and other various processing such as boring a hole can be performed suitably.
Hereinafter, the reason why a cutting method for chemical fibers made of nylon or polyester fiber cannot be applied for cutting carbon fibers will be explained. When chemical fibers are cut by a contact cutting with blade 35 as described above, trouble of fraying at the edge face has been caused like carbon fibers. However, because chemical fibers take three states of solid, liquid and gas when heated under ordinary temperature and ordinary pressure, the fraying can be prevented by a method such as cutting with a blade which has been heated to a temperature higher than the melting point of the chemical fiber and melting the edge face fibers simultaneously with cutting as using friction heat which has been generated between the blade and the chemical fiber during cutting.
On the other hand, the same principle cannot be applied to a carbon fiber which sub-limes under ordinary temperature and ordinary pressure and which takes two states of solid and gas. Carbon could take three states under a pressurized condition. However, it is not realistic because ultra-high pressure around 100 MPa is required to generate such a pressurized condition. Accordingly, the above-described laser processing is performed to make it possible to form graphitized part 40 directly on the surface and/or the edge face without preparing any material, such as carbon and halogenated hydrocarbon, other than layered carbon-fiber product 20.
Next, RTM forming method as an example of methods to form fiber reinforced plastic 145 with layered carbon-fiber product 20 or preform 30 will be explained with
The difference of fiber reinforced plastics 145 manufactured with preforms 30, which have been cut by different cutting methods in RTM molding method, will be explained.
Preform 30 is positioned in a predetermined-shaped cavity which is formed in lower die 116. Therefore, unless the edge part of preform 30 is properly treated, troubles might be caused like the edge part of fiber reinforced plastic 145 has insufficient strength after forming or burrs are generated. Specific examples will be explained with
In
The postprocessing of fiber reinforced plastic obtained after hardening will be explained with
Further, when edge faces 157, 167 and 177 of thus prepared three kinds of fiber reinforced plastics 155, 165 and 175 are touched with a tool of spanner wrench 180, etc., by mistake of work, cracks 158 and 168 are developed greatly from edge faces 157 and 167 on fiber reinforced plastics 155 and 165 in pattern 1 and pattern 2, while there generated few crack on fiber reinforced plastic 175 in pattern 3. Crack generation depends on the internal structure of the fiber reinforced plastics. Reinforced plastics are isotropic products prepared by layering carbon fiber fabrics to give required rigidity and strength along a specified direction as well as products formed by heating and cooling resin material with which a carbon-fiber preform is impregnated. Therefore, each layer composing the fiber reinforced plastic has a strain along a different direction, and inherently has a residual strain and a residual stress between layers. Therefore, if there exist carbon-fiber bundles and carbon-fiber fabrics on the edge face of fiber reinforced plastics or they are exposed by cutting, an impact power applied to the edge face tends to generate cracks between carbon fibers, carbon-fiber bundles and carbon-fiber fabrics.
In contrast thereto, because net-shape preform 171 having the graphitized part on edge face 177 by cutting with laser beam, etc. is provided with graphite film 45 as described above when such an impact power is applied thereto, graphite film 45 would function as a breakwater and prevent generating such cracks between carbon fibers, carbon-fiber bundles and carbon-fiber fabrics. As a result, simplification of postprocessing leads to a combined effect that the low cost and short production time are achieved by reducing manpower and that the durability against the impact power onto the edge face, fatigue strength and rigidity are secured.
Although the preform which is cut with a laser beam and provided with the graphitized part on the edge face has been explained, another method to bind carbon fibers on the edge face may be employed as well. For example, the edge face may be hardened by induction hardening applied to metal materials. Further, material such as metals may be coated although there remains the problem of specific gravity, etc.
To prevent a crack from developing on the edge face of fiber reinforced plastics which have been formed, a method such as a method to overlay material made from resin material and reinforcing fibers to cover the cut edge face and a method to apply resin material to the edge face, can be employed to not expose fiber reinforced plastics between carbon fibers, carbon-fiber bundles and carbon-fiber fabrics.
Another case to process a preform desirably with laser beam will be explained with
As to a preform of which the surface is made of graphitized carbon fibers, laser beam 222 is replaced with a torch for cutting and is radiated according to scanning profile 230 to cut preform to prepare a preform 31 at a product side.
Although an example where the laser beam is radiated to only a side of the preform is shown in
Hereinafter, desirable examples will be explained. This disclosure is not, however, limited to the following practical examples.
A carbon-fiber fabric matrix (CK6252: manufactured by Toray Industries, Inc., T700S, 12K, plain weave) as a carbon-fiber fabric obtained by weaving a unidirectional carbon-fiber bundle made of carbon fibers arranged in a single direction was prepared. After a thermoplastic tackifier resin (10 g/m2, Tg=70° C., average particle diameter 200 μm) was applied to one surface of the carbon-fiber fabric matrix, the tackifier resin was softened and adhered thereto as running between far-infrared heater plates to prepare a tackifier-adhered carbon-fiber fabric matrix. The tackifier-adhered carbon-fiber fabric matrix was cut to 150 mm*150 mm with a rotary cutter (manufactured by OLFA company) to prepare ten sheets in total.
Next, each tackifier-adhered carbon-fiber fabric matrix was respectively ironed as covering a glass sheet made of Teflon (registered trademark) to soften the tackifier resin and bind it to adjacent tackifier-adhered carbon-fiber fabric matrix. Such a process was continued to prepare a preform made by 10 sheets of layered tackifier-adhered carbon-fiber fabric matrixes.
Such a prepared preform was applied to processing test device 210 shown in a schematic diagram in
As a result, graphite film 45 having linear mark 41, which is shown in
Next, a part of graphite film 45 was exfoliated from the edge face of cut preform in Practical Example 1.
The result of the laser Raman spectroscopy analysis is shown in
According to such a comparison of the intensity ratios, the graphite film and the graphitized carbon-fiber edge part are further carbonized than the carbon fiber.
A cutting processing test was performed under a condition where the processing atmosphere was changed from nitrogen to air (nonuse of nozzle 225) in the condition of Practical Example 1. As a result, graphite film 45 having linear mark 41, which is shown in
Next, like Practical Example 1, a total of three kinds of edge faces, which included a region in which graphite film was attached to a part of graphite film 45 was exfoliated from the edge face of the preform in Practical Example 1, a region from which graphite film was exfoliated and in which graphitized carbon-fiber edge part was exposed, and a carbon-fiber edge part exposed on an edge face of a uncut preform, were subjected to a laser Raman spectroscopy analysis with the same devices under the same analysis condition of Practical Example 1. The analytical result of the laser Raman spectroscopy analysis is shown in
The analytical result which has been subjected to baseline correction to remove the influence of the fluorescence background is shown in
According to such a comparison of the intensity ratios, the graphitized edge face, as well as the graphite film and the graphitized carbon-fiber edge part like Practical Example 1, is further carbonized than the carbon fiber. Since the profile shows well the result (
A cutting processing test was performed under a condition where the processing condition was changed to pulse wave in the condition of Practical Example 1. As a result, graphite film 45 having linear mark 41, which is shown in
A cutting processing test was performed under a condition where the laser processing machine was changed from disk laser to fiber laser, and the processing condition was changed to the energy density of 6.4*10−6 (W/μm2) in the condition of Practical Example 1. As a result, graphite film 45 having linear mark 41, which is shown in
A cutting processing test was performed under a condition where carbon-fiber fabric matrix (CO6343: Toray T300, 3K, plain weave) was used as a carbon-fiber fabric for the preform in the condition of Practical Example 4. As a result, graphite film 45 having linear mark 41, which is shown in
A cutting processing test was performed under a condition where the processing condition was changed to the output power of 100W, and the energy density of 3.2*105 (W/μm2) in the condition of Practical Example 1, as using the same preform 200 and processing test device 210. As a result, preform 200 was not able to be penetrated with laser beam 70 and some sheets were left uncut.
After having manufactured the same preform as Practical Example 1 by using the tackifier-adhered carbon-fiber fabric matrix used in Practical Example 5, the filler agent which was epoxy type adhesive diluted with an organic solvent for preventing raveling at the cut edge face was applied to the neighborhood of cutting line (not shown) corresponding to the scanning profile in Practical Example 1. An automatic cutter provided with a round blade was Used as the cutting processing machine. The preform was placed on a vacuum table, which is not shown and is covered with a film cover to be vacuumed to fix the preform on the vacuum table while the cutting test was performed. The automatic cutter is a cutter which is generally, used in an apparel business and which has a mechanism for running on X- and Y-axis.
Few frays were generated on the cut edge face of the preform by an effect of the filler agent. However, since the filler agent had adhesiveness, single carbon fibers, which seemed to have been fallen off a cut surface of the cut preform, were attached to the surface of the round blade, together with the filler agent. Such a result is not good, because the filler agent might cause impurity adherence to the preform edge face and the carbon fiber might be fallen off and frayed.
A cutting processing test was performed under a condition where the filler agent was not applied to the neighborhood of the cutting line in the condition of Comparative Example 2. When the cut preform would be removed from the vacuum table, some carbon fibers were clipped in the vacuum table and the fray was caused on the edge face of the preform. In addition, cut carbon fibers were left at a corner of the preform which had been shaped into a rectangle by cutting. Such a result is not good because, without the filler agent, carbon fibers might be frayed or remain at the time of corner processing.
The preform manufactured in Comparative Example 2 was cut by hand work with a round blade (OLFA product) without using a cutting processing machine. The cutting was performed with the round blade of which surface was touching with an edge face of a ruler placed along a cutting line mark, on a cutting mat made of rubber.
The fray was generated on the cut edge face of the preform as shown in
Number | Date | Country | Kind |
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2009-285882 | Dec 2009 | JP | national |
This is a §371 of International Application No. PCT/JP2010/071863, with an international filing date of Dec. 7, 2010 (WO 2011/074437 A1, published Jun. 23, 2011), which is based on Japanese Patent Application No. 2009-285882, filed Dec. 17, 2009, the subject matter of which is incorporated by reference.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/JP2010/071863 | 12/7/2010 | WO | 00 | 6/13/2012 |