JP6321446B2 - Method for cutting reinforced fiber substrate and method for producing fiber reinforced resin - Google Patents

Description

  The present invention relates to a technique for cutting a reinforced fiber base material and a fiber reinforced resin, and more particularly to a technique for cutting a reinforced fiber base material and a fiber reinforced resin with a laser.

  Carbon fiber reinforced resin (CFRP) is attracting attention as a lightweight and high-strength material. In recent years, its use is expanding not only in the aerospace field but also in other industrial fields such as the automotive field. is there. Such CFRP is molded by various methods such as a prepreg / autoclave method. Among them, the resin injection molding (RTM: Resin Transfer Molding) method is highly productive and can be easily reduced in cost and complicated. It is expected as a molding method that can be easily molded into a shape. In the RTM method, a CFRP having a desired shape is formed by charging a preform made of carbon fiber into a mold and then impregnating the preform in the mold with a matrix resin and curing the preform.

  A preform used in the RTM method is formed by cutting a carbon fiber woven fabric or a carbon fiber substrate made of a laminate of carbon fiber woven fabrics in accordance with the shape of a mold. When the preform is formed, if the carbon fiber base material is mechanically cut, the carbon fiber in the cut portion is disturbed, and the dimensional accuracy of the preform may be lowered.

  When the dimensional accuracy of the preform is low, various problems occur when forming CFRP by the RTM method. For example, if the preform is smaller than the mold, the preform will be displaced in the mold, and the flow of resin will be faster in the gap between the preform and the mold, and the resin will be sufficiently in the center of the molded product. May not penetrate. On the other hand, if the preform is larger than the mold, the fiber orientation is distorted, affecting the strength of the molded product, and the flow of the resin may be disturbed. Therefore, in order to form a preform with higher dimensional accuracy, it has been proposed to cut the carbon fiber substrate with a laser (see, for example, Patent Document 1).

International Publication 2011/114592 Pamphlet

  However, when a carbon fiber substrate is cut by a laser, the carbon fiber substrate is affected by heat, such as contamination around the cut portion by the sizing material decomposed by the heat of the laser, or graphitization of the carbon fiber by the laser heat. May occur. This problem is not limited to the case of cutting a carbon fiber base material, but also when cutting various reinforcing fiber base materials such as a glass fiber woven fabric and its laminate, and an aramid fiber woven fabric and its laminate. May occur. Further, even when the CFRP is cut by a laser, the resin of the matrix material is decomposed and altered by the heat of the laser, and the cut portion may be damaged.

  The present invention has been made to solve the above-described conventional problems, and cuts a cutting target with high dimensional accuracy while reducing the influence of heat on the reinforcing fiber base material or fiber reinforced resin to be cut. The purpose is to provide technology.

In order to achieve at least a part of the above object, the present invention can be realized as the following forms or application examples.
The method for cutting a reinforcing fiber substrate according to one aspect of the present invention includes a laser beam irradiation step of cutting the reinforcing fiber substrate by irradiating a laser beam a plurality of times to a cutting line where the reinforcing fiber substrate is cut. In addition, the light source of the laser beam is a CO ₂ laser. According to this method for cutting a reinforcing fiber substrate, since the reinforcing fiber substrate is cut by irradiating the cutting line with the laser beam a plurality of times, heat flows into the irradiation position of the laser beam per irradiation. The amount can be reduced and the influence of laser heat on the reinforcing fiber base can be suppressed. Further, by cutting with a laser, the reinforcing fiber base can be cut with higher dimensional accuracy. Furthermore, since the wavelength of the CO ₂ laser is as long as about 10 μm, it is considered that the heat absorption rate of the reinforcing fiber base is higher than that when a laser beam having a shorter wavelength is irradiated. Therefore, the cutting speed can be further increased by using a CO ₂ laser as the light source of the laser beam .

[Application Example 1]
A method for cutting a reinforcing fiber substrate, comprising a laser beam irradiation step of cutting the reinforcing fiber substrate by irradiating a cutting line for cutting the reinforcing fiber substrate with a laser beam a plurality of times. How to cut the material.

  According to this application example, since the reinforcing fiber base material is cut by irradiating the cutting line with the laser beam a plurality of times, the amount of heat flowing into the irradiation position of the laser beam per irradiation can be reduced. Can do. Therefore, it is possible to suppress the influence of laser heat on the reinforcing fiber base. Further, by cutting with a laser, the reinforcing fiber base can be cut with higher dimensional accuracy.

[Application Example 2]
The method for cutting a reinforcing fiber base according to Application Example 1, wherein the laser beam irradiation step irradiates the laser beam a plurality of times by scanning the laser beam a plurality of times along the cutting line.

  In this application example, the laser beam is irradiated onto the cutting line by scanning the laser beam, so that the moving speed of the laser beam irradiation position can be increased. Therefore, the time required for cutting the reinforcing fiber base can be shortened by increasing the output of the laser beam.

[Application Example 3]
In the method for cutting a reinforcing fiber substrate according to Application Example 1, in the laser beam irradiation step, the irradiation position of the laser beam is reciprocated in a linear region including a cutting point on the cutting line. A method for cutting a reinforcing fiber substrate, comprising: a reciprocating scanning step of scanning a laser beam; and a cutting point moving step of moving the cutting point along the cutting line.

  According to this application example, since the irradiation position of the laser beam is reciprocated by scanning the laser beam, the moving speed of the irradiation position of the laser beam can be increased. Therefore, the time required for cutting the reinforcing fiber base can be shortened by increasing the output of the laser beam. In addition, by moving the cutting point, it is possible to cut the reinforcing fiber base in a wider range than the scanning range of the laser beam.

[Application Example 4]
4. The method for cutting a reinforcing fiber substrate according to application example 2 or 3, wherein the laser beam is scanned by a galvano scanner.

  The galvano scanner can easily widen the scanning range of the laser beam as compared with other scanning means. Therefore, the reinforcing fiber substrate can be cut in a wider range by scanning the laser beam with a galvano scanner. Further, since the galvano scanner is suitable for reciprocating scanning with a laser beam, the irradiation position of the laser beam can be reciprocated more easily.

[Application Example 5]
5. The method for cutting a reinforcing fiber substrate according to any one of application examples 1 to 4, wherein the laser beam is a pulse beam.

  By making the laser beam a pulse beam, even if the output of the laser beam is increased, the average amount of heat flowing into the laser beam irradiation position is reduced. Therefore, the influence of the heat of the laser on the reinforcing fiber base can be more effectively suppressed.

[Application Example 6]
6. The method for cutting a reinforcing fiber substrate according to any one of application examples 1 to 5, wherein a light source of the laser beam is a CO ₂ laser.

Since the wavelength of the CO ₂ laser is as long as about 10 μm, it is considered that the heat absorption rate of the reinforcing fiber base is higher than that when a laser beam having a shorter wavelength is irradiated. Therefore, the cutting speed can be further increased by using a CO ₂ laser as the light source of the laser beam.

[Application Example 7]
A method of cutting a fiber reinforced resin, wherein the laser beam irradiation position scans the laser beam so as to reciprocate a linear region including a cutting point on a cutting line where the fiber reinforced resin is cut. A method for cutting a fiber reinforced resin, comprising: a step; and a cutting point moving step of moving the cutting point along the cutting line.

  According to this application example, since the fiber reinforced resin is cut by irradiating the cutting line with the laser beam a plurality of times, the amount of heat flowing into the irradiation position of the laser beam per irradiation can be reduced. it can. Therefore, it is possible to suppress the influence of laser heat on the fiber reinforced resin. Further, by cutting with a laser, the fiber reinforced resin can be cut with higher dimensional accuracy.

  Note that the present invention can be realized in various modes. For example, a method of cutting a reinforcing fiber base, a preform manufactured by the method, a method of manufacturing a fiber reinforced resin using the method, a fiber reinforced resin manufactured by the manufacturing method, and a method of cutting the fiber reinforced resin , And the like.

Process drawing which shows the molding process of CFRP to which the first embodiment is applied. Explanatory drawing which shows a mode that a laminated woven fabric is cut | disconnected in 1st Embodiment. Explanatory drawing which shows the process in which a laminated woven fabric is cut | disconnected and a preform is cut out. The photograph which shows the cutting condition at the time of irradiating a test piece with a laser beam. The photograph which shows the external appearance of the cutting part at the time of irradiating a laser beam several times and cut | disconnecting. The photograph which shows the external appearance of the cutting part vicinity when changing the frequency | count of irradiation of a laser beam, and cutting a test piece. A photograph showing the appearance of a test piece when cut into a circle. Explanatory drawing which shows a mode that a laminated woven fabric is cut | disconnected in 2nd Embodiment. Photograph showing the appearance of a cut specimen with CO ₂ laser to continuous wave. Photograph showing the appearance of a cut specimen with CO ₂ laser to pulsed. The photograph which shows the external appearance of the cut surface at the time of cut | disconnecting a prepreg laminated body.

Hereinafter, modes for carrying out the present invention will be described in the following order.
A. First embodiment:
A1. Molding of carbon fiber reinforced resin:
A2. Cutting laminated woven fabric:
A3. Example of the first embodiment:
B. Second embodiment:
B1. Cutting laminated woven fabric:
B2. Example of the second embodiment:
C. Third embodiment:
C1. CFRP cutting:
C2. Example of the third embodiment:
D. Variations:

A1. Molding of carbon fiber reinforced resin:
FIG. 1 is a process diagram showing a molding process of a carbon fiber reinforced resin (CFRP) to which the first embodiment is applied. This CFRP molding process is called a resin injection molding (RTM) method. In the CFRP molding process by the RTM method, first, as shown in FIG. 1A, a laminated woven fabric 10 in which a plurality of carbon fiber woven fabrics are laminated is cut along a cutting line 20. Thereby, the preform 30 cut | disconnected by the desired shape (in the example of FIG. 1 circular) is obtained. A method for cutting the laminated woven fabric 10 will be described later.

  Next, the obtained preform 30 is placed on the lower mold 40 (FIG. 1B). After the preform 30 is placed on the lower mold 40, the upper mold 50 is placed on the lower mold 40 and clamped as shown in FIG. Thereafter, vacuuming is performed from the suction hole 52 provided in the upper mold 50, and a thermosetting resin (for example, epoxy resin) is injected from the injection hole 54 to impregnate the preform 30 with the thermosetting resin. . After the impregnation with the thermosetting resin, the molds 40 and 50 are heated to cure the thermosetting resin and form the CFRP molded product 32 to which the shapes of the molds 40 and 50 are transferred. The CFRP molded product 32 is obtained by removing the formed CFRP molded product 32 from the molds 40 and 50 (release) (FIG. 1D).

  In the example of FIG. 1, CFRP is molded by the RTM method, but CFRP can also be molded by using the VaRTM method. In the CFRP molding process by the VaRTM method, first, a bag film is attached to the molding die so as to cover the preform placed on the surface of the molding die. Next, the gap between the bag film and the mold is evacuated, and a thermosetting resin is injected into the gap to impregnate the preform with the thermosetting resin. After impregnation with the thermosetting resin, the thermosetting resin is cured by heating the entire mold, the preform impregnated with the thermosetting resin, and the bag film, and a CFRP molded product is obtained.

  In the first embodiment, after the preform is impregnated with the thermosetting resin, the thermosetting resin is cured by heating to obtain a CFRP molded product. However, the preform is impregnated with the thermoplastic resin. It is also possible to produce a molded product of fiber reinforced thermoplastic resin (CFRTP). In this case, the molds 40 and 50 are heated before resin injection. Then, after the resin is injected and the preform is impregnated with the resin, the molds 40 and 50 are cooled to obtain a CFRTP molded product.

A2. Cutting carbon fiber woven fabric:
FIG. 2 is an explanatory view showing a state in which the laminated woven fabric 10 is cut by the cutting device 60 in the first embodiment, and FIG. 3 is a preform 30 (see FIG. 1) after the laminated woven fabric 10 is cut. It is explanatory drawing which shows the process in which is cut out. FIG. 3A shows the state of the laminated woven fabric 10 at the time of starting cutting, and FIGS. 3B and 3C show the state of the laminated woven fabric 10 at the time of cutting. Is shown. 2 and 3 (c) show states at the same time point.

  The cutting device 60 includes a laser light source (not shown), a galvano scanner 100, a table 210 that can be moved in the XY direction, and a receiving jig 220 that is fixed on the table 210 and on which the laminated woven fabric 10 is disposed. doing. In the first embodiment, a single mode fiber laser is used as the laser light source, and a pulse beam emitted by oscillating the single mode fiber laser is used as the laser beam LB. The receiving jig 220 suppresses the heat generated when the laminated woven fabric 10 is cut from being transmitted to the table 210. Thereby, generation | occurrence | production of the cutting failure by the dissipation of the heat | fever from the laminated woven fabric 10 and the damage of the table 210 by the dissipated heat are suppressed. In the first embodiment, the positional relationship between the galvano scanner 100 and the laminated woven fabric 10 is fixed. Therefore, in the first embodiment, a table in which at least one of the X direction and the Y direction is fixed may be used instead of the table 210 movable in the XY direction.

  The galvano scanner 100 includes two galvanometer mirrors 110 and 120 and an f-θ lens 130. The galvanometer mirrors 110 and 120 have mirrors 112 and 122, holders 114 and 124, shafts 116 and 126, and a drive unit (not shown), respectively. The drive unit rotates the shafts 116 and 126 around their axes (indicated by a one-dot chain line). As the shafts 116 and 126 rotate, the directions of the reflecting surfaces 118 and 128 of the mirrors 112 and 122 attached to the shafts 116 and 126 via the holders 114 and 124 change. Thus, by changing the direction of the reflecting surfaces 118 and 128, the direction of the laser beam LB incident on the galvano scanner 100 is dynamically changed (scanned). The laser beam LB scanned by the two galvanometer mirrors 110 and 120 is converged on the laminated woven fabric 10 by the f-θ lens 130, and a minute spot SP of the laser beam LB is formed.

  When the emission of the laser beam LB from the laser light source is started at the start of cutting, a spot SP of the laser beam LB is formed on the laminated woven fabric 10 as shown in FIG. The spot SP irradiated with the laser beam LB scans the laser beam LB by driving and controlling the galvanometer mirrors 110 and 120 (FIG. 2), so that a target cutting line (shown by a broken line) ( It moves along the target cutting line 22). By moving the spot SP irradiated with the laser beam LB, each point of the target cutting line 22 is irradiated with the laser beam LB, and as a result, the entire target cutting line 20 is irradiated with the laser beam LB. Become. As is clear from the above description, the moving direction of the spot SP is a direction along the target cutting line 22 and can also be referred to as a cutting direction.

  FIG. 3B shows a state in which the spot SP has returned to the position of the cutting start point (FIG. 3A) by moving the spot SP along the target cutting line 22. In the first embodiment, the output of the laser beam LB (output of the laser light source) and the scanning speed (moving speed of the spot SP) are set so that the laminated woven fabric 10 is not completely cut by one irradiation of the laser beam LB. It is adjusted. Therefore, at the time shown in FIG. 3B, the path 24 along which the spot SP has moved is in a semi-cut state where the laminated woven fabric 10 is not cut completely. Since the moving path 24 of the spot SP is a linear region in a semi-cut state as described above, it is hereinafter referred to as a semi-cut line 24.

  As shown in FIG. 3B, after the spot SP has returned to the position of the cutting start point (FIG. 3A), the spot SP is further moved along the semi-cut line 24. Thereby, at the time point shown in FIG. 3C, in the path 26 along which the spot SP has moved, the laminated woven fabric 10 that has been in the semi-cut state along the semi-cut line 24 is completely cut. In addition, since the path 26 of the spot SP that has moved along the half-cut line 24 becomes a linear region in which the laminated woven fabric 10 is completely cut, it is hereinafter referred to as a full cut line 26. When the spot SP returns again to the position of the spot SP at the starting point of cutting (FIG. 3A), the entire cutting line 26 is closed, and the laminated woven fabric 10 is separated inside and outside of the entire cutting line 26, and is circular. The preform 30 (FIG. 1A) is cut out. As is clear from FIG. 3, the target cutting line 22, the half cutting line 24, and the entire cutting line 26 are all the same linear region, and are therefore collectively referred to as the cutting line 20.

  In the example of FIG. 3, the laminated woven fabric 10 is completely cut by moving the spot SP twice along the cutting line 20, that is, by irradiating the laser beam LB twice. In this case, the laminated woven fabric 10 may be completely cut by irradiating the laser beam LB a plurality of times along the cutting line 20. Thus, by cutting the laminated woven fabric 10 by irradiating the laser beam LB a plurality of times, the amount of heat flowing into the irradiation position (the position of the spot SP) of the laser beam LB per irradiation is suppressed. Therefore, the influence of heat on the preform 30 can be reduced.

  In the first embodiment, the galvano scanner 100 is used for scanning with the laser beam LB (that is, movement of the spot SP). Thereby, the position of the spot SP can be adjusted with sufficiently high accuracy with respect to the diameter (10 to 100 μm) of the spot SP. However, if the position of the spot SP can be adjusted with an accuracy equal to or higher than that of the galvano scanner 100, other scanning devices can be used. As such a scanning device, for example, a scanning device using an acousto-optic element can be used. However, it is preferable to use a galvano scanner because it is easy to widen the scanning range and obtain a larger preform 30.

  In the first embodiment, the spot SP on the laminated woven fabric 10 is moved by scanning the laser beam LB. However, if the position of the spot SP can be adjusted with sufficiently high accuracy, the laser beam LB is used. The spot SP may be moved mechanically without scanning. In this case, the table 210 may be moved, or an irradiation head that directly irradiates the laminated woven fabric 10 with the laser beam LB may be moved. However, since the moving speed of the spot SP can be further increased, the laser beam LB can be shortened by increasing the output of the laser beam LB and shortening the time required for cutting the laminated woven fabric 10. Are preferably scanned. In general, the focal length of the lens (converging lens) that converges the laser beam LB in the irradiation head that directly irradiates the cutting target with the laser beam LB is shorter than the focal length of the converging lens of the scanning device. Thus, when the focal length of the converging lens is shortened, the amount of change in the diameter of the spot SP when the position in the Z direction changes increases. Therefore, it is more preferable to move the spot SP by scanning with the laser beam LB in that the change in the diameter of the spot SP can be suppressed.

In the first embodiment, a single mode fiber laser is used as the laser light source, but a multimode fiber laser can also be used. However, the use of a single mode fiber laser is preferable to the use of a multimode fiber laser in that the laser beam LB can be narrowed more narrowly. Further, as the laser light source, various laser light sources capable of emitting a high-power laser beam LB such as a CO ₂ laser and a YAG laser can be used in addition to the fiber laser. In the fiber laser, a laser beam emitted from another laser light source can be easily passed through the optical fiber, and the optical system can be easily handled. Therefore, when the spot SP is mechanically moved, it is preferable to use a fiber laser.

In a laser light source other than the fiber laser, it is preferable to use a CO ₂ laser capable of emitting a laser beam LB having a wavelength (about 10 μm) at which the heat absorption rate of the laminated woven fabric 10 is high. More preferably, a CO ₂ laser capable of pulse oscillation in a single mode, which can increase the cutting speed by narrowing the laser beam LB, is used. In such a CO ₂ laser, a laser beam LB having a small focal beam diameter is emitted in a single mode by pulse oscillation. However, in general, a CO ₂ laser capable of pulse oscillation in a single mode has a limit in the output of the emitted laser beam LB, and therefore a thick woven fabric 10 (for example, a thickness of 4 mm or more) is used. It is not always easy to cut. Therefore, it is preferable to use a CO ₂ laser capable of pulse oscillation in a single mode for high-speed cutting of a thin woven fabric 10 (for example, a thickness of less than 4 mm).

  In the first embodiment, a pulse beam emitted by oscillating a laser light source is used as the laser beam LB. However, a continuous beam emitted by oscillating the laser light source continuously may be used. However, even if the output of the laser beam LB is increased, the average amount of heat flowing into the laser beam irradiation position is reduced, and the effect of the laser heat on the laminated woven fabric 10 can be more effectively suppressed. In view of this, it is preferable to use a pulse beam. Note that when cutting a thin woven fabric 10 having a thickness of less than 4 mm (for example, less than 4 mm), the output of the laser beam LB can be lowered. The average amount of heat inflow can be reduced.

A3. Example of the first embodiment:
[Preparation of specimen]
In order to evaluate the state of the laminated woven fabric cut by the cutting method of the first embodiment, a test piece corresponding to the laminated woven fabric 10 to be cut (FIG. 1A) was prepared. Specifically, first, as a carbon fiber woven fabric constituting a laminated woven fabric (test piece), a carbon fiber woven fabric was prepared by weaving a yarn in which 12,000 long carbon fiber filaments were bundled into a plain weave. The prepared carbon fiber woven fabric had a thickness of 0.22 mm and a weight of 210 g / m ² . Next, a plurality of prepared carbon fiber woven fabrics were laminated to obtain a test piece. The number of laminated carbon fiber woven fabrics was 8 and 16. In the following, when clearly indicating the number of laminated carbon fiber woven fabrics, a test piece with 8 laminated sheets is called an “8-ply test piece”, and a test piece with 16 laminated sheets is called a “16-ply test”. It is called a piece.

[Number of laser beam irradiation and cutting of laminated fabric]
The relationship between the number of times of laser beam irradiation and the cutting state of the laminated woven fabric was evaluated. Evaluation of the relationship between the number of irradiations and the cutting state was performed by irradiating a 16-ply test piece with a laser beam in a straight line for a preset number of times and observing the appearance of the test piece after laser beam irradiation. A single mode fiber laser was used as the laser light source, and pulse oscillation was performed at a pulse frequency of 1500 Hz. The laser beam output was 500 W, and the spot moving speed (laser beam scanning speed) was 750 mm / min.

  FIG. 4 is a photograph showing a cutting state when a test piece is irradiated with a laser beam. 4 (a) to 4 (c) are photographs showing the side appearance of the test piece when the laser beam is irradiated once to three times, respectively. In FIG. 4A to FIG. 4C, the arrows indicate the irradiation position of the laser beam, that is, the position of the cutting line (cutting portion).

  As shown in FIG. 4A, in the test piece irradiated with the laser beam once, only the surface layer portion on the laser beam irradiation surface (hereinafter, also simply referred to as “irradiation surface”) side was cut. Further, as shown in FIG. 4B, even in the test piece irradiated with the laser beam twice, the cut area became deep, but the test piece was not completely cut. On the other hand, in the test piece irradiated with the laser beam three times, as shown in FIG. 4C, the test piece was completely cut. In FIGS. 4 (a) to 4 (c), the cut portion indicated by the arrow appears to be fluffy, but this fluff is generated when the appearance of the side is observed and remains cut. In this state, the fiber was not disturbed at the cut portion.

[Evaluation of cut shape]
The form of the cut portion when the laminated woven fabric was cut by irradiating the laser beam multiple times was evaluated. The evaluation was performed by irradiating the 8-ply test piece twice with the laser beam and cutting the test piece, and then observing the appearance of the irradiated surface and the cross section (cut surface) of the cut portion. The type of laser light source and its oscillation conditions, the output of the laser beam, and the scanning speed of the laser beam are the same as when the relationship between the number of irradiations and the cutting state was evaluated.

  FIG. 5 is a photograph showing the appearance of the cut part when it is cut by irradiating a laser beam a plurality of times. FIG. 5A and FIG. 5B show the appearance of the irradiated surface and the appearance of the cut surface, respectively. As can be seen from FIG. 5A, no fiber disturbance occurred at the cut portion. Further, although the test piece was irradiated with the laser beam twice, the cutting width was not widened, and it was confirmed that the scanning accuracy of the laser beam LB by the galvano scanner 100 (FIG. 2) was sufficiently high. It was. Furthermore, as shown in FIG.5 (b), it has confirmed that carbon fiber was crowded in the cut surface and the disorder of the fiber did not arise in the cut part.

[Evaluation of heat effects]
The influence of heat applied to the laminated woven fabric when it was cut by irradiation with a laser beam was evaluated. The evaluation is based on the case where the test piece is cut by irradiating the laser beam once as a comparative example using the 8-ply test piece, and the case where the test piece is cut by irradiating the laser beam twice as an example. This was done by observing changes in the appearance appearing on the irradiated surface near the cut portion. The type of laser light source, its oscillation conditions, and the output of the laser beam were the same as when the relationship between the number of irradiations and the cutting situation was evaluated. The scanning speed of the laser beam was set to 400 mm / min so that the test piece could be completely cut by one irradiation when the laser beam was irradiated and cut once. On the other hand, when the laser beam was irradiated twice for cutting, it was set to 750 mm / min, which was the same as when the relationship between the number of times of irradiation and the cutting state was evaluated.

  FIG. 6 is a photograph showing the appearance of the vicinity of the cut portion when the test piece is cut while changing the number of times of irradiation with the laser beam. FIG. 6A and FIG. 6B respectively show a test piece (Comparative Example) cut by irradiating the laser beam once and a test piece (Example) cut by irradiating the laser beam twice. The appearance of the irradiated surface in the vicinity of the cut portion is shown. As can be seen from FIG. 6A and FIG. 6B, the expansion of the region where discoloration is observed in the vicinity of the cut portion is more twice than the comparative example in which the laser beam is irradiated once and cut. The example cut by irradiation was narrower. From this, it was confirmed that the influence of heat on the preform was reduced by irradiating the laser beam a plurality of times to cut the laminated woven fabric.

[Preform formation by multiple laser beam irradiation]
It was confirmed that a preform could be formed by irradiating a 16-ply test piece with a laser beam multiple times. Specifically, the test piece was cut into a circular shape by irradiating a laser beam three times along a circular cutting line having a diameter of 30 mm. The type of laser light source and its oscillation conditions, and the output and scanning speed of the laser beam are the same as when the relationship between the number of irradiations and the cutting state is evaluated.

  FIG. 7 is a photograph showing the appearance of the test piece when cut into a circle. FIG. 7A shows the outer appearance of the cutting line, and FIG. 7B shows the outer appearance of the cutting line. As can be seen from FIG. 7A and FIG. 7B, it was confirmed that the shape of the cut portion was in a good state both inside and outside the cutting line. It was also confirmed that the laminated woven fabric can be cut with high dimensional accuracy by scanning the laser beam with the galvano scanner 100 (FIG. 2).

  As described above, by cutting the laminated woven fabric by irradiating the laser beam a plurality of times, the laminated woven fabric can be obtained with high dimensional accuracy while suppressing the influence of heat on the laminated woven fabric to be cut and the disturbance of the fibers in the cut portion. It was confirmed that the cloth could be cut. In addition, it was confirmed that the spread of the cutting width can be suppressed by scanning the laser beam with sufficiently high accuracy using a galvanometer mirror.

B1. Cutting carbon fiber woven fabric:
FIG. 8 is an explanatory diagram showing a state in which the laminated woven fabric 10 is cut by the same cutting device 60 as in the first embodiment in the second embodiment. The second embodiment is different from the first embodiment in that the shape of the cutting line 20a is different, the point in which the table 210 is moved, and the scanning mode of the laser beam LB by the galvano scanner 100 is different. Is different. Other points are the same as in the first embodiment. In FIG. 8, for convenience of illustration, only a part of the closed cutting line 20a is illustrated.

  In the second embodiment, the shafts 116 and 126 of the galvano scanner 100 are driven and controlled, and at least one of the mirrors 112 and 122 is rotationally oscillated. As a result, a spot (not shown) that is the irradiation position of the laser beam LB is reciprocally oscillated (reciprocated) in a linear region that extends in the tangential direction (cutting direction) of the cutting line 20a around the cutting point CP on the cutting line 20a. Moving. When the spot is reciprocally oscillated within a linear region (hereinafter also referred to as “reciprocating region”), the laser beam LB is irradiated a plurality of times in the vicinity of the cutting point CP, so that the laminated woven fabric 10 is completely cut. When the table 210 is moved so that the cutting point CP moves along the target cutting line 22a, the laminated woven fabric 10 is completely cut in the path along which the cutting point CP has moved. It is formed. In the second embodiment, the spot is oscillated back and forth within the linear reciprocating region. However, the reciprocating region may not be linear as long as it is a linear region including the cutting point CP. For example, a part of the cutting line 20a in the vicinity of the cutting point CP can be a reciprocating region. Further, the cutting point CP only needs to be located in the reciprocating area, and does not necessarily need to be an intermediate point of the reciprocating area.

  In the second embodiment, the spot in the reciprocating region is reciprocally oscillated by the galvano scanner 100. Therefore, when the laser beam LB is irradiated for the half cycle of the reciprocating vibration, that is, when the laser beam LB is irradiated once, the moving speed of the spot can be increased to the extent that the laminated woven fabric 10 is not cut. In this way, by increasing the moving speed of the spot to such an extent that the laminated woven fabric 10 is not cut by one irradiation of the laser beam LB, heat flows into the position of the spot SP, that is, the irradiation position of the laser beam LB. Since the amount can be suppressed, the influence of heat on the preform can be reduced.

  Thus, also in the second embodiment, the laminated woven fabric 10 is cut by irradiating the laser beam LB a plurality of times. Therefore, since the amount of heat flowing into the irradiation position of the laser beam LB can be suppressed, the influence of heat on the preform can be reduced. Also in the second embodiment, since the laminated woven fabric 10 is cut by the laser beam LB, the laminated woven fabric 10 can be cut with high dimensional accuracy.

  In the second embodiment, the cutting point CP is moved by moving the table 210. In general, the moving range of the mechanical moving device such as the table 210 is wider than the scanning range of the laser beam LB by the scanning device such as the galvano scanner 100. Therefore, the second embodiment is preferable to the first embodiment in that a larger preform can be cut out by irradiating the laser beam LB over a wider range. On the other hand, the first embodiment is preferable to the second embodiment in that the preform can be cut out only by the scanning of the laser beam LB by the galvano scanner 100, so that the control becomes easier.

  Also in the second embodiment, the laser beam LB may be scanned using various scanning devices such as a scanning device using an acousto-optic element instead of the galvano scanner 100. However, the galvano scanner 100 can easily perform reciprocating scanning around a predetermined direction (origin direction) due to the structure of the structure portion. Therefore, scanning with the laser beam LB is preferably performed using the galvano scanner 100. In the second embodiment, the table 210 is moved to move the cutting point CP. However, instead of moving the table 210, the galvano scanner 100 may be moved.

B2. Example of the second embodiment:
[State evaluation of cut laminated woven fabric]
The state of the laminated woven fabric cut by the cutting method of the second embodiment was evaluated. In the evaluation, an 8-ply test piece (laminated woven fabric) prepared in the same manner as in the example of the first embodiment was cut linearly. As a light source of the laser beam LB (FIG. 8), a continuously oscillating CO ₂ laser was used, and the output of the laser beam LB was adjusted to 250 W. Then, the test piece was moved in one direction at 5 mm / s, and the spot of the laser beam LB was reciprocally oscillated with an amplitude of 10 mm and a vibration frequency of 1 Hz along the moving direction of the test piece by the galvano scanner 100. For comparison, the test piece was cut without reciprocating the spot.

FIG. 9 is a photograph showing the appearance of a test piece cut using a continuously oscillating CO ₂ laser. FIG. 9A shows the appearance of the irradiated surface in the vicinity of the cut portion. FIG. 9B and FIG. 9C show the appearance of the side surface of the cut portion when the spot is not reciprocally vibrated (without vibration) and when the spot is reciprocally vibrated (with vibration), respectively. ing. As can be seen from FIG. 9 (a), the expansion of the area where discoloration is observed in the vicinity of the cut portion is narrower when the spot is reciprocally oscillated than when the spot is not reciprocally oscillated. From this, it was confirmed that the influence of heat on the preform is reduced by reciprocating the spot. Further, as can be seen from FIGS. 9B and 9C, it can be confirmed that even when the spot is reciprocally vibrated, the test piece can be completely cut as in the case where the spot is not reciprocally vibrated. It was.

FIG. 10 is a photograph showing the appearance of a test piece cut using a pulsed CO ₂ laser. FIG. 10A shows the appearance of the irradiation surface in the vicinity of the cutting portion, and FIG. 10B shows the appearance of the side surface of the cutting portion. The test piece cutting conditions shown in FIG. 10 differ from the test piece cutting conditions shown in FIG. 9 in that the CO ₂ laser is oscillated and the laser beam output is 500 W. The other points are the same as the cutting conditions of the test piece shown in FIG. Note that the pulse oscillation conditions of the CO ₂ laser were a pulse frequency of 1500 Hz and a pulse width of 0.2 μs.

As can be seen from FIG. 10 (a), the expansion of the region in which discoloration is observed in the vicinity of the cut portion is narrower when the spot is reciprocally oscillated than when the spot is not reciprocally oscillated. From this, it was confirmed that the influence of heat on the preform can be reduced by reciprocating the spot. Further, it was found that regardless of the presence or absence of reciprocal vibration, the CO ₂ laser was oscillated in pulses, so that the discoloration region spread was narrower and the influence of heat on the preform could be reduced more than in the case of continuous oscillation. This is presumably because the average heat inflow was reduced despite the high output of the laser beam because the laser beam was pulsed. Further, as can be seen from FIG. 10B, it was confirmed that even when the spot was reciprocally oscillated, the test piece could be completely cut as in the case where the spot was not reciprocally oscillated.

C1. CFRP cutting:
The third embodiment is different from the second embodiment in that the CFRP is cut instead of the laminated woven fabric 10 (FIG. 8). Since other points are the same as those of the second embodiment, the description thereof is omitted here. Also in the third embodiment, the position of the spot SP, that is, the position of the laser beam LB is increased by reciprocally vibrating the spot and increasing the moving speed of the spot to such an extent that the CFRP is not cut by one irradiation of the laser beam LB. Since the amount of heat flowing into the irradiation position can be suppressed, the influence of heat on the CFRP can be reduced.

  In addition, the object of cutting in the third embodiment is not limited to CFRP using carbon fibers as reinforcing fibers and using a thermosetting resin as a matrix material, and may be various fiber reinforced resins. The present invention uses, for example, carbon fiber as a reinforcing fiber, carbon fiber reinforced thermoplastic resin (CFRTP) using a thermoplastic resin as a matrix material, glass fiber as a reinforcing fiber, and thermosetting or thermoplastic as a matrix material. It is also possible to apply to the cutting of a glass fiber reinforced resin using Aramid fiber and aramid fiber reinforced resin using aramid fiber as a reinforcing fiber and thermosetting or thermoplastic as a matrix material.

C2. Example of the third embodiment:
[Preparation of specimen]
In order to evaluate the state of CFRP cut by the cutting method of the third embodiment, a test piece corresponding to the CFRP to be cut was prepared. Specifically, first, a prepreg in which carbon fibers having a thickness of 0.2 mm were arranged in one direction was prepared. Next, eight prepared prepregs were laminated so that the carbon fiber directions of adjacent prepregs were different from each other, to obtain a quasi-isotropic prepreg laminate (prepreg laminate). And the test piece was obtained by pinching the obtained prepreg laminated body with the aluminum plate whose thickness is 0.2 mm.

[Evaluation of heat effects]
The influence of heat when cutting by irradiating with a laser beam was evaluated. The evaluation was performed by observing changes in appearance appearing on the cut surface of the test piece between the case where the laser beam was cut without reciprocating vibration of the spot and the case where the laser beam was cut by reciprocating vibration as a comparative example. . As the laser light source, a continuous mode single mode fiber laser was used, and the output of the laser beam was adjusted to 250 W. Then, the test piece was moved in one direction at 10 mm / s, and the laser beam spot was reciprocally vibrated at a frequency of 1 Hz and an amplitude of 10 mm along the moving direction of the test piece by a galvano scanner. For comparison, the test piece was cut without reciprocating the spot.

  FIG. 11 is a photograph showing the appearance of a cut surface when a test piece (prepreg laminate) is cut. 11 (a) and 11 (b), respectively, a test piece in which the spot was cut without reciprocating vibration (no vibration) as a comparative example, and the spot was reciprocated and vibrated (with vibration) as an example. The external appearance of a cut surface with a test piece is shown. As can be seen from FIGS. 11 (a) and 11 (b), the prepreg laminate was completely cut by irradiation with the laser beam regardless of the presence or absence of the reciprocal vibration of the spot. On the other hand, the size of the heat affected zone indicated by the arrow was reduced by reciprocating the spot. From this, it was confirmed that the influence of heat on the prepreg laminate (CFRP) is reduced by reciprocating the spot.

  As described above, in the third embodiment, the amount of heat flowing into the irradiation position of the laser beam is suppressed by reciprocating the spot, so that it is an object to be cut when the laser beam is irradiated for cutting. The influence of heat on CFRP can be reduced. Also in the third embodiment, since the CFRP is cut by the laser beam, the CFRP can be cut with high dimensional accuracy.

D. Variations:
The present invention is not limited to the above-described embodiments and examples, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.

D1. Modification 1:
In the first and second embodiments, the preform is cut out by cutting the laminated woven fabric 10 (FIG. 1) along the closed cutting lines 20 and 20a (FIGS. 2 and 8). However, the present invention is not limited to the case of cutting along the closed cutting lines 20 and 20a in order to obtain a preform, and is generally applicable when cutting a laminated woven fabric. In the present invention, for example, in order to remove an unnecessary portion of a laminated woven fabric, when cutting a part of its peripheral portion, or when making a cut in a preform for facilitating the formation of a three-dimensional shape Furthermore, when preparing a laminated woven fabric for cutting out the preform, the present invention can be applied to various cases such as cutting the laminated woven fabric into an appropriate size in advance.

D2. Modification 2:
In the first and second embodiments, the cutting target is the laminated woven fabric 10 (FIG. 1) in which a plurality of carbon fiber woven fabrics are stacked, but the cutting target is not limited to this. The first and second embodiments are, for example, a carbon fiber woven fabric that is not laminated, a glass fiber woven fabric in which glass fiber yarns are woven, and a laminate thereof, an aramid fiber woven fabric in which aramid fiber yarns are woven, and It is also possible to apply to cutting of various reinforcing fiber substrates such as laminates.

DESCRIPTION OF SYMBOLS 10 ... Laminated fabric 20, 20a ... Cutting line 22, 22a ... Target cutting line 24 ... Half cutting line 26, 26a ... Full cutting line 30 ... Preform 32 ... CFRP molded product 40 ... Lower die 50 ... Upper die 52 ... Suction hole 54 ... Injection hole 60 ... Cutting device 100 ... Galvano scanner 110,120 ... Galvano mirror 112,122 ... Mirror 114,124 ... Holder 116,126 ... Shaft 118,128 ... Reflective surface 130 ... F-θ lens 210 ... Table 220 ... Receiving jig CP ... Cutting point LB ... Laser beam SP ... Spot

Claims (6)

A method for cutting a reinforcing fiber substrate,
Look including a laser beam irradiation step of cutting the reinforcing fiber base material by irradiating multiple times with a laser beam cutting line the reinforcing fiber base is cut,
The light source of the laser beam is a CO ₂ laser,
A method for cutting a reinforcing fiber substrate.   The method for cutting a reinforcing fiber base according to claim 1, wherein the laser beam irradiation step irradiates the laser beam a plurality of times by scanning the laser beam a plurality of times along the cutting line. A method for cutting a reinforcing fiber substrate according to claim 1,
The laser beam irradiation step includes
A reciprocating scanning step of scanning the laser beam so that the irradiation position of the laser beam reciprocates a linear region including a cutting point on the cutting line;
A cutting point moving step of moving the cutting point along the cutting line;
including,
A method for cutting a reinforcing fiber substrate.   The method for cutting a reinforcing fiber substrate according to claim 2 or 3, wherein the laser beam is scanned by a galvano scanner.   The method for cutting a reinforcing fiber substrate according to any one of claims 1 to 4, wherein the laser beam is a pulse beam. A method for producing a fiber reinforced resin,
Cutting the reinforcing fiber substrate by the method according to any one of claims 1 to 5 to form a preform;
Impregnating the preform with a resin;
including,
Manufacturing method of fiber reinforced resin.