JP7615905B2 - Cutting device and cutting method - Google Patents

Description

Article 30, paragraph 2 of the Patent Act applies. ・Proceedings of the 2021 Spring Symposium on Plastic Processing WEB Lectures (606) available for download on May 27, 2021. ・Materials from the 2021 Spring Symposium on Plastic Processing WEB Lectures held on June 4, 2021.

The present invention relates to a cutting device and a cutting method, and more specifically, to a cutting device and a cutting method that can be used to cut materials that contain fibers.

Carbon fiber reinforced plastic (CFRP) is a lightweight, high-strength material that is used as a structural material in the automotive industry and other fields. Due to its high strength, CFRP is difficult to process, and cutting, drilling, and other processes are performed by abrasive water jet processing, laser processing, turning, and other processes. However, all of these processing methods process point-like areas, and when processing a wide area, such as cutting into a specific component shape, it is necessary to change the positional relationship with the processing method while processing. As a result, the time required for processing is long, and it cannot be said that the processing efficiency is excellent.

Therefore, in order to increase the processing efficiency when processing CFRP materials, the use of shear cutting has been considered. Shear cutting allows linear areas to be processed at once, so the time required for processing can be reduced. An apparatus and method for shear cutting CFRP materials are disclosed, for example, in Patent Document 1 below.

International Publication No. 2013/175657

When shear cutting is performed on CFRP material, fuzz and uneven structures originating from the carbon fibers are formed on the end surface obtained by shear cutting, making it difficult to obtain a smooth end surface. Increasing the smoothness of the end surface is important from the viewpoint of the dimensional accuracy of the manufactured parts. It is possible to obtain a smooth end surface by subsequently processing the end surface of the CFRP material obtained by shear cutting to remove the fuzz and uneven structure, but in that case, the processing process will require time and effort, and the effect of improving processing efficiency by applying shear cutting will not be fully realized. Similar problems can occur when shear cutting is performed on resin materials containing fibers other than CFRP material.

The problem that this invention aims to solve is to provide a cutting device and cutting method that can obtain smooth cut end surfaces with high processing efficiency when cutting resin materials that contain fibers, such as carbon fiber reinforced plastics, by shearing.

In order to solve the above problems, the cutting device according to the present invention is a cutting device for cutting a workpiece made of a resin material containing fibers, and has a lower blade arranged on the lower surface side, which is one side of the workpiece, a plate holder arranged on the upper surface side, which is the other side of the workpiece, facing the lower blade, and an upper blade arranged adjacent to the plate holder on the upper surface side of the workpiece and moving along a moving direction from the upper surface side to the lower surface side, and the upper blade has a first blade arranged forward along the moving direction and a second blade arranged backward along the moving direction, in succession, and the first blade can shear the workpiece, and the second blade is arranged to protrude toward the plate holder side from the first blade, and can scrape off the structure of the end surface of the workpiece.

Here, the cutting device may further include a reverse holding blade disposed opposite the upper blade on the lower surface side of the workpiece. In this case, the reverse holding blade may be movable in the vertical direction. Furthermore, the reverse holding blade may be attached to a die cushion. Also, the cutting edge of the first blade may be at an acute angle.

The cutting method according to the present invention uses the above-mentioned cutting device to cut a workpiece made of a plate-shaped resin material containing fibers, and in a state in which the workpiece is sandwiched and fixed between the lower blade and the plate holder, the upper blade is moved from the top side of the workpiece to the bottom side, and the workpiece is shear-cut with the first blade, and the structure of the end surface of the workpiece obtained in the first step is scraped off with the second blade in succession.

Here, the material to be cut may be carbon fiber reinforced plastic. The cutting device may further include a reverse clamp blade disposed opposite the upper blade on the underside of the material to be cut, the reverse clamp blade being movable in the vertical direction, and the first step may be performed with the reverse clamp blade elevated, and the second step may be performed with the reverse clamp blade lowered further than in the first step.

The cutting device according to the present invention is equipped with an upper blade having a first blade and a second blade in succession. When the upper blade is moved from the upper surface side to the lower surface side of the material to be cut, the material to be cut is first shear-cut by the first blade. In this state, the end surface obtained by shear cutting may have protruding fibers of the material to be cut or may have irregular structures such as unevenness. However, by further lowering the upper blade, the second blade, which is located at a position closer to the plate holder than the first blade, will then cut away these structures. In this way, the shear cutting by the first blade and the scraping away of the structure by the second blade can be performed continuously by a single upper blade, and a smooth cut end surface in which fuzzing and uneven structures caused by the presence of fibers are suppressed can be obtained with high processing efficiency.

Here, if the cutting device further has a counter blade arranged opposite the upper blade on the underside of the material to be cut, the cut end surface by the first blade of the upper blade is formed outside the part where the material to be cut is held by the lower blade and the plate holder, and the structure that can be scraped off by the second blade is more likely to remain reliably at the end of the material to be cut. Therefore, through shear cutting by the first blade and scraping off by the second blade, it becomes easier to form a highly smooth cut end surface in the desired position.

In this case, if the reverse blade is movable in the vertical direction, the reverse blade can be raised while the first blade is shearing the material to be cut, so that an upward load is applied from the reverse blade to the material to be cut, and the cut end surface by the first upper blade can be reliably formed outside the part where the material is held by the lower blade and plate holder. On the other hand, by lowering the reverse blade while the second blade is scraping off the structure of the end surface of the material to be cut, collision between the reverse blade and the upper blade can be prevented. In this case, if the reverse blade is attached to a die cushion, the vertical movement of the reverse blade can be easily achieved by using the die cushion provided in a typical die press device.

In addition, if the cutting edge of the first blade is at an acute angle, the first blade will more easily shear the material being cut at the desired position, making it easier to obtain a cut end surface with a high level of smoothness.

In the cutting method according to the present invention, the above-mentioned cutting device having an upper blade in which a first blade and a second blade are provided consecutively can be used to shear the material to be cut with the first blade and scrape off the end surface structure with the second blade in a single process. Therefore, a smooth cut end surface with little fuzz or uneven structure caused by the fibers contained in the material to be cut can be obtained with high processing efficiency.

Here, when the material to be cut is carbon fiber reinforced plastic (CFRP), cutting can be performed while ensuring smoothness of the cut end surface in CFRP material, which has high material strength. Methods that process point-like areas, such as abrasive water jet processing, are mainly used to process CFRP material, but the cutting method of the present invention can process linear areas in one go by shear cutting, and there is no need to perform a separate process to smooth the end surface, so the processing efficiency in cutting CFRP material can be significantly improved.

In addition, the cutting device further has a reverse blade arranged opposite the upper blade on the lower surface side of the material to be cut, and the reverse blade is movable in the vertical direction. When the first step is performed with the reverse blade raised and the second step is performed with the reverse blade lowered from the first step, the shear cutting in the first step is performed while applying an upward load from the reverse blade to the material to be cut, which makes it easier to form a cut end surface by the first blade of the upper blade at a position outside the part where the material to be cut is held by the lower blade and the plate holder. Then, the structure that can be scraped off by the second blade is reliably left on the end of the material to be cut, and the end surface finally obtained after the second step is less likely to have the low smoothness structure formed in the first step. On the other hand, when performing the second step, by lowering the reverse blade, it is possible to scrape off the structure on the end surface of the material to be cut while avoiding collision between the reverse blade and the upper blade. As a result, a smooth cut end surface can be efficiently formed through the first and second steps.

1 is a side view showing a configuration of a cutting device according to an embodiment of the present invention. 1A is a side view showing a state in which a workpiece is cut by the cutting device, and FIG. 1B is a side view showing a state in which a workpiece is cut by shear cutting with a first blade, and FIG. 1B is a side view showing a state in which a workpiece is cut by a second blade. These are images taken of the process of cutting a CFRP material using a cutting device, with the cutting progressing from (a) to (h). These are photographs showing the cut end surface of a CFRP material, with the smoothness of the end surface improving from smoothness 1 (left side) to smoothness 5 (right side). The top image is a photograph of the overall appearance of the cut end surface, and the bottom image is an enlarged image of the cross section.

The cutting device and cutting method according to an embodiment of the present invention are described in detail below. The cutting device according to this embodiment is a device for cutting a workpiece made of a resin material containing fibers, and the cutting method according to this embodiment is a method for cutting a workpiece using such a cutting device.

The specific type of material to be cut is not particularly limited, but the following description will be mainly based on the assumption that carbon fiber reinforced plastic (CFRP) is used as a suitable material to be cut. CFRP is a material that combines high strength with light weight. In particular, carbon fiber reinforced thermoplastic resin (CFRTP), which uses a thermoplastic resin as the base resin, can be suitably applied as the material to be cut. The shape of the material to be cut is not particularly limited, but a plate or sheet shape is suitable. The thickness of the plate or sheet-shaped material to be cut is not particularly limited, but a range of 1 mm or more and 5 mm or less can be exemplified as suitable examples.

[Cutting device]
Fig. 1 shows a side view of the structure near the die of a cutting device 1 according to one embodiment of the present invention. In the following, the directions of up, down, left and right are shown according to the directions in the figure. In Fig. 1, gaps are provided between each component so that the boundaries between the components can be easily seen.

The cutting device 1 according to this embodiment is configured as a press device, and uses a die including an upper die with an upper blade 10 and a lower die with a lower blade 20 to cut the material W to be cut, which contains fibers W1, into a predetermined shape determined by the shapes of the upper blade 10 and the lower blade 20. The cutting device 1 according to this embodiment can be constructed by attaching a die with a blade of a predetermined shape, as described below, to a conventional die press device that has been used to cut metal materials.

The cutting device 1 according to this embodiment has a lower blade 20 arranged on the lower surface W3 side, which is one surface of the workpiece W, and an upper blade 10 and a plate holder 40 arranged on the upper surface W2 side, which is the other surface. In addition, the cutting device 1 optionally has a reverse holder blade 30 on the lower surface W3 side.

The plate holder 40 is positioned opposite the lower blade 20 with the workpiece W sandwiched between them. The workpiece W can be fixed by sandwiching it between the lower blade 20 and plate holder 40. The upper blade 10 is positioned adjacent to the plate holder 40. In the figure, the upper blade 10 is positioned to the right of the plate holder 40. When cutting the workpiece W, the upper blade 10 can move along a moving direction (vertical direction) from the upper surface W2 side to the lower surface W3 side of the workpiece W.

When the reverse pressure blade 30 is provided, it is positioned opposite the upper blade 10 with the workpiece W sandwiched between them. The reverse pressure blade 30 is attached to a die cushion (not shown). A die cushion is also provided in conventional general die press devices for the purpose of applying a load to the lower die, and can move up and down due to air pressure, etc. The movement of the die cushion allows the reverse pressure blade 30 to move up and down.

The upper blade 10 and the lower blade 20 each have a blade surface at a location including the edge along the vertical direction. The material W to be cut can be cut by moving the upper blade 10 downward along the movement direction while the material W is sandwiched between the lower blade 20 and the plate holder 40. In the illustrated example, the material W is supported in a cantilever manner by the lower blade 20 and the plate holder 40 to cut the material W, but depending on the desired processing shape, the material W may be supported at multiple positions separated from each other and punched between these support positions.

The upper blade 10 has two regions, a first blade 11 and a second blade 12. The first blade 11 is provided forward (below) along the direction of movement of the upper blade 10, and the second blade 12 is provided backward (upward) along the direction of movement of the upper blade 10. The upper blade 10 and the lower blade 20 are continuous with each other along the up-down direction, and constitute the upper blade 10 as an integrated member.

The first blade 11 is provided at the tip of the upper blade 10, and when the upper blade 10 is lowered, a shear force is applied to the workpiece W, thereby shearing the workpiece W. The second blade 12 is provided continuously above the first blade 11, but the edge of the upper blade 10 along the vertical direction is not linear from the first blade 11 to the second blade 12, and the second blade 12 is provided protruding further toward the plate holder 40 side (left side of the figure) than the first blade 11. As will be described in detail later about the cutting method, when the upper blade 10 is lowered, the second blade 12 scrapes off the structure of the workpiece W, including the end surface obtained by the shear cutting by the first blade 11.

In the upper blade 10, the angle θ1 of the cutting edge of the first blade 11 is preferably an acute angle. Furthermore, the angle θ3 of the tip of the reverse holding blade 30 is also preferably an acute angle. It is more preferable that the angle θ1 of the cutting edge of the first blade 11 and the angle θ3 of the cutting edge of the reverse holding blade 30 are both 20° or more and 70° or less. In particular, it is preferable that the cutting edge angles θ1 and θ3 are about 45°±5°. Note that the angle θ2 of the cutting edge of the second blade 12 of the upper blade 10 and the angle θ4 of the cutting edge of the lower blade 20 do not need to be acute angles, and may be approximated to a right angle.

The dimensions of each part of the upper blade 10 may be set appropriately depending on the thickness and characteristics of the material W to be cut, but it is preferable that the length D1 of the first blade 11 along the vertical direction be set so that the first step of the cutting method described below can shear and cut almost the entire area along the thickness direction of the material W to be cut. In addition, from the viewpoint of preventing the reverse holding blade 30 from escaping before the second blade contacts the material W to be cut, it is preferable that the length D1 of the first blade 11 be shorter than the thickness of the material W to be cut. In addition, the distance (step D2) by which the second blade 12 protrudes toward the plate holder 40 side relative to the first blade 11 may be set so that the position of the second blade 12 is outside the reverse holding blade 30, and the line (straight line L1 in FIG. 1) connecting the tip of the upper blade 10 and the tip of the reverse holding blade 30 is not inclined by 45° or more relative to the thickness direction of the material W to be cut, and the structure of the end surface of the material W obtained through the first step can be sufficiently scraped off by the second blade 12. As described above, when the workpiece W is made of CFRP material with a thickness of 1 mm or more and 5 mm or less, the length D1 of the first blade 11 can be preferably exemplified as being in the range of 0.5 mm or more and 2.5 mm or less. In addition, the step D2 between the first blade 11 and the second blade 12 can be preferably exemplified as being in the range of 0.2 mm or more and 3.6 mm or less, more preferably 1 mm or less.

[Cutting method]
Next, a cutting method according to an embodiment of the present invention will be described. In this method, the cutting device 1 described above is used to cut a workpiece W made of a resin material containing fibers W1.

Prior to cutting the material W, the material W is sandwiched and held between the lower blade 20 and plate holder 40 of the cutting device 1. The upper blade 10 is positioned above the upper surface W2 of the material W. If the cutting device 1 has a reverse holding blade 30, the tip of the reverse holding blade 30 is in contact with the lower surface W3 of the material W. Then, the die cushion to which the reverse holding blade 30 is attached is held in a raised position, and an upward load F is applied to the reverse holding blade 30.

From this state, the upper blade 10 is moved downward (motion M). As the upper blade 10 moves downward, the first step shown in FIG. 2(a) and the second step shown in FIG. 2(b) are carried out in this order.

In the first step shown in FIG. 2(a), the first blade 11, which is provided at the lower part of the upper blade 10, bites into the material W to be cut. The first blade 11 applies a shear force to the material W to be cut from the upper surface W2, and shears and cuts the material W between the first blade 11 and the reverse holding blade 30. However, since the material W to be cut has a structure in which the fibers W1 are embedded in the resin material, the cut end surface E1 obtained by the shear cutting in the first step is likely to have fuzz and unevenness due to the protruding fibers W1 and the irregular structure of the tissue containing the fibers W1, and the smoothness of the end surface E1 is likely to be low. In particular, when the material W to be cut is made of CFRP material, the carbon fibers have high strength and are not easily subjected to shear cutting, so the low smoothness of the cut end surface E1 is noticeable.

Therefore, in order to improve the smoothness of the cut edge of the workpiece W, the second step shown in FIG. 2(b) is carried out following the first step. If the cutting device 1 has a reverse pressure blade 30 and the reverse pressure blade 30 is held in a raised position by the die cushion while the first step is being carried out, it is advisable to lower the reverse pressure blade 30 before carrying out the second step by releasing the air pressure in the die cushion, for example.

The second step is performed by the second blade 12 of the upper blade 10. After the first step, when the upper blade 10 continues to be lowered (movement M), the cut end surface E1 formed by the shear cutting by the first blade 11 in the first step or the tissue in the vicinity thereof comes into contact with the second blade 12, and the second step is performed. In the second step, the second blade 12 scrapes off the tissue W' of the material W to be cut, including the cut end surface E1 obtained in the first step (shaving). Since the second blade 12 is provided at a position protruding toward the plate holder 40 side from the first blade 11, the second blade 12 scrapes off the tissue W' of the material W to be cut, including the cut end surface E1 with low smoothness generated through the first step, at a position that is closer to the inside of the material W to be cut than the cut end surface E1 (left side of the figure), and a highly smooth end surface E2 is newly formed at a position inside the original cut end surface E1.

In this way, by cutting the material W to be cut using the upper blade 10 equipped with both the first blade 11 that shears the material W to be cut and the second blade 12 that shaves the area including the cut edge E1 of the material W to be cut, even if the material W to be cut contains fibers W1 and it is difficult to form a smooth cut end surface by simply shearing it, a smooth cut end surface E2 can be easily formed by a single cutting operation. The smoothness of the cut end surface E2 obtained through cutting with the first blade 211 and the second blade 12 is increased, thereby improving the dimensional accuracy of the member formed by cutting. It is also possible to prevent the fibers W1 protruding from the cut end surface from piercing the worker's hand.

Furthermore, when the cutting device 1 is equipped with a reverse holding blade 30 and the first blade 11 of the upper blade 10 performs shear cutting in the first step while the reverse holding blade 30 supports the workpiece W from below, the cracks caused by the shear tend to progress along the line (straight line L1 in FIG. 1) connecting the tip of the upper blade 10 and the tip of the reverse holding blade 30, or outside that line. Then, the cut end surface E1 formed by the first blade 11 is less likely to penetrate inside the area sandwiched between the lower blade 20 and the plate holder 40 (left side of the figure), and is formed outside that area (right side of the figure). Then, after the first step, the texture W' of the workpiece W is left outside the area sandwiched between the lower blade 20 and the plate holder 40, and this remaining texture W' is shaved by the second blade 12 in the second step. Then, after the second step, the surface exposed as the cut end surface of the workpiece W is composed of the smooth end surface E2 obtained by shaving with the second blade 12, without leaving the low-smooth end surface E1 obtained by shear cutting with the first blade 11. In this way, by performing the shear cutting with the first blade 11 in the first step in cooperation with the reverse pressure blade 30, the smoothness of the final cut edge E2 can be effectively increased. If the reverse pressure blade 30 is lowered before starting the second step, it is possible to avoid collision between the upper blade 10 and the reverse pressure blade 30 during the second step.

In addition, the angle of the cutting edge of the first blade 11 of the upper blade 10 is acute, which effectively improves the smoothness of the cut end surface E2 obtained through the first and second steps. This is thought to be because the proportion of the shear surface is greater than the fracture surface in the cut end surface E1 formed through the first step. The effect can be maximized when the angle of the cutting edge of the upper blade 10 is around 45°. Furthermore, if the cutting edge of the reverse pressing blade 30 is also acute, the position where the crack is formed by the cutting by the first blade 11 of the upper blade 10 is likely to be determined at the position connecting the tip of the upper blade 10 and the tip of the reverse pressing blade 30 (the straight line L1 in FIG. 1). Therefore, through the first and second steps, it becomes easier to form a highly smooth cut end surface E2 at the desired position with high precision.

The present invention will be explained in more detail below using examples.

[1] Condition of the blade and the workpiece during cutting First, the conditions of the blade and the workpiece during cutting were confirmed in the process of cutting the workpiece using the cutting device described above.

[Test Method]
As shown in FIG. 1, a cutting device equipped with an upper blade, a lower blade, a plate holder, and a reverse holder blade was used to carry out the test. As described above, the upper blade was equipped with a first blade and a second blade. The angles θ1 and θ3 of the cutting edge of the first blade and the reverse holder blade of the upper blade were both 45°. The angles θ2 and θ4 of the cutting edge of the second blade and the lower blade of the upper blade were both 90°. The length D1 of the first blade was 1 mm. The step D2 between the first blade and the second blade of the upper blade was 0.6 mm, and the clearance between the upper blade and the plate holder was 0.6 mm at the position of the first blade and 0 mm at the position of the second blade. The clearance between the lower blade and the reverse holder blade was 0.1 mm. The width of the blade (the dimension in the depth direction of the drawing) was 30 mm. Each blade was made of SKD11 material (hardness: 60HRC).

The material to be cut was a unidirectional CFRTP sheet (thickness 0.16 mm, base resin PA6, Vf 50%), laminated in 12 layers with the fibers perpendicular to each other and heated and pressed together. The dimensions of the material to be cut were length 30 mm, width 10 mm, and thickness 1.9 mm.

One end of the material to be cut in the width direction was clamped and fixed between the lower blade and the plate holder. Furthermore, the tip of the reverse pressure blade was brought into contact with the underside of the material to be cut, and the pneumatic die cushion to which the reverse pressure blade was attached was raised. In this state, the upper blade was lowered from the top side of the material to be cut, and the material was cut. The load on the die cushion was 30 kN, and the average movement speed of the upper blade was 2 mm/s. When the material to be cut was broken by the first blade, the descent of the upper blade was temporarily stopped, the air pressure in the die cushion was released, and the reverse pressure blade was lowered. The descent of the upper blade was then resumed.

As the upper blade was lowered to cut the material, the area including each blade and the material was photographed from the side of the material with a high-speed video camera to confirm the condition of the material and each blade. The filming speed was 300 fps.

[Test Results]
Figure 3 shows images captured by a high-speed video camera. The upper blade descends from image (a) to image (h), and cutting progresses. Image (a) shows the state in which the cutting edges of the upper blade and the counter blade are in contact with the top and bottom surfaces of the workpiece before cutting begins. In the captured image, the carbon fiber layer contained in the workpiece made of CFRTP material appears dark.

When the upper blade is lowered from the state shown in image (a), a shear crack occurs between the first blade and the reverse holding blade of the upper blade, as shown in image (b), and the material to be cut is cut from above and below. On the top side, the upper blade cuts through to the third layer of the CFRTP sheet laminate. When the upper blade is lowered further, cutting of the material to be cut progresses, and in the state shown in image (c), a complete fracture has occurred. In other words, the material to be cut is cut across the entire thickness direction.

When the material being cut is broken in image (c), the descent of the upper blade is temporarily stopped in the state shown in image (d). At this time, the cut end surface cut by the first blade can be seen on the left side of the upper blade, and it can be seen that this end surface has irregularities. Although it is difficult to see in the image because part of this end surface is darkened by the shadow of the upper blade and the reverse blade, it is located outside the material being cut (to the right of the image) from the position where the material is fixed by the lower blade and the plate holder.

After that, in the state shown in image (e), the air pressure in the die cushion is released and the reverse pressure blade is lowered. Furthermore, from image (f) onwards, the descent of the upper blade resumes, and in the process from images (f) to (h), the second blade cuts away the structure at the end of the material being cut. The cutting position is on the inside of the material being cut (the left side of the image) rather than the cut end surface formed by the shear cut with the first blade. As shown by the arrow in the photographed image in image (g), the shavings cut away by the second blade are also photographed.

In the photographed image (h), the second blade reaches the bottom surface of the workpiece. This shows that a new straight edge has been formed inside the cut edge formed by the shear cut with the first blade, although it is darkened by the shadow of the upper blade.

As described above, it has been confirmed that by using an upper blade equipped with a first blade and a second blade, it is possible to continuously shear the material to be cut with the first blade and shave the edge of the material to be cut with the second blade. The position where the shear cut is performed with the first blade is outside the position where the material to be cut is fixed by the lower blade and the plate holder, and the position where shaving is performed with the second blade is inside the cut edge formed by the first blade.

[2] Configuration of the cutting device and state of the cut portion Next, the relationship between the configuration of the cutting device and the state of the end surface obtained by cutting was examined.

[Test Method]
As in the above test [1], the CFRTP material was cut using a cutting device. However, the configuration of the blades in the cutting device was based on the configuration in the above test [1], and at least one of the following parameters was changed in each of Examples 1 to 7 and Comparative Examples 1 and 2: the presence or absence of a second blade in the upper blade, the presence or absence of a counter-pressing blade, the cutting edge angles θ1 and θ3 of the upper blade and the counter-pressing blade, and the material of the upper blade. The configuration of Example 2 was the same as the configuration adopted in the above test [1].

The appearance of the end surface obtained by cutting was photographed with a camera, and the cross-section was photographed with a stereomicroscope. In addition, the maximum length of fuzz (structure containing fibers protruding from the end surface) was measured on the end surface.

[Test Results]
FIG. 4 shows, in table form, the appearance photographs and cross-sectional states of the end faces of representative samples. It can be seen that the smoothness of the end faces differs greatly depending on the sample. From left to right in the table, the fuzzing on the end faces decreases, and the smoothness of the cross-section also improves. Here, the smoothness of the end faces was evaluated according to the length (L) of the fuzzing on the end faces. When 1.5 mm≦L, it was given a smoothness of 1, when 1.0 mm≦L<1.5 mm, it was given a smoothness of 2, when 0.5 mm≦L<1.0 mm, it was given a smoothness of 3, when 0.1 mm≦L<0.5 mm, it was given a smoothness of 4, and when L<0.1 mm, it was given a smoothness of 5. When the smoothness is 5, there is almost no fuzzing visible in the appearance photograph, and a very smooth cross-section is obtained. From the viewpoint of the dimensional accuracy required in processing CFRTP materials, when the smoothness is 1 or 2, it is considered to be unacceptable, and when it is 3 to 5, it is considered to be acceptable.

Table 1 below summarizes the blade configuration of the cutting device and the evaluation results of the smoothness of the cut area.

As shown in Table 1, in all of Examples 1 to 7, the upper blade is provided with a second blade in addition to the first blade, whereas in Comparative Examples 1 and 2, the upper blade is not provided with a second blade, and the upper blade is composed only of a blade for shear cutting that corresponds to the first blade. Furthermore, in Examples 1 to 7, a smooth cross section with a smoothness of 3 or more, which can be considered acceptable, is obtained at the cut portion, whereas in Comparative Examples 1 and 2, the smoothness is 2 or less, which is a low level that is unacceptable. From this, it can be seen that a highly smooth end surface can be obtained by forming the upper blade into a two-stage structure of a first blade and a second blade, shearing the material to be cut with the first blade, and then shaving the end surface with the second blade.

Furthermore, whereas Examples 1 to 4 use a reverse pressure blade, Examples 5 and 6 do not. When comparing the smoothness of the cut portions between the set of Examples 1 and 6, in which the angles of the tips of the upper blade and reverse pressure blade are the same, and the set of Examples 2 and 5, Examples 5 and 6, in which no reverse pressure blade is used, both have a smoothness of 4, whereas Examples 1 and 2, in which a reverse pressure blade is used, both have a smoothness of 5, which is extremely smooth. This shows that the smoothness of the cut end surface can be particularly improved by using a reverse pressure blade.

In Examples 1 to 4, the angles of the cutting edges of the first blade of the upper blade and the reverse holding blade are different from each other. When comparing these, in Example 4, where the cutting edge angle is 90°, the state of the cut part remains at a smoothness of 3, whereas in Examples 1 to 3, where the cutting edges are acute, a very smooth cut surface with a smoothness of 5 is obtained. From this, it can be seen that by making the cutting edges of the upper blade and the reverse holding blade acute angles, the smoothness of the cut end surface can be particularly improved. The sets of Examples 5 and 6 and the sets of Comparative Examples 1 and 2 also have different cutting edge angles, and when Comparative Example 1 and Comparative Example 2 are compared to each other, Comparative Example 2, where the cutting edge angle is 30°, is slightly smoother than Comparative Example 1, where the angle is 60°. It is suggested that keeping the cutting edge angle small, approximately 45° or less, can be highly effective in improving the smoothness of the cut surface.

Although Example 7 differs from Example 1 in the constituent material of the upper blade, both Example 1 and Example 7 obtain a highly smooth cutting surface rated at a smoothness of 5. This confirms that the above findings obtained by mutually comparing Examples 1 to 6 and Comparative Examples 1 and 2 are not obtained by using a specific type of steel for the upper blade.

The above describes the embodiments of the present invention. The present invention is not limited to these embodiments, and various modifications can be made.

1 Cutting device 10 Upper blade 11 First blade 12 Second blade 20 Lower blade 30 Reverse holding blade 40 Plate holder D1 Length of first blade D2 Step E1 Cut edge formed by first process E2 Cut edge formed by second process F Load M applied to reverse holding blade from die cushion Movement of upper blade W Material to be cut (CFRP material)
W1 Fiber (carbon fiber)
W2 Upper surface W3 Lower surface W' Tissue to be removed θ1 Angle of the cutting edge of the first blade θ2 Angle of the cutting edge of the second blade θ3 Angle of the cutting edge of the counter blade θ4 Angle of the cutting edge of the lower blade

Claims (8)

A cutting device for cutting a workpiece made of a resin material containing fibers, comprising:
A lower blade is disposed on a lower surface side of the workpiece, which is one surface of the workpiece;
A plate holder is disposed on the other surface of the workpiece, i.e., on the upper surface side, facing the lower blade;
An upper blade is disposed adjacent to the plate holder on the upper surface side of the workpiece and moves along a moving direction from the upper surface side to the lower surface side,
The upper blade has a first blade disposed forward along the moving direction and a second blade disposed backward along the moving direction, which are successively arranged,
The first blade is capable of shear cutting the workpiece,
The second blade is provided protruding toward the plate holder side more than the first blade, and is capable of scraping off the structure of the end surface of the workpiece. The cutting device according to claim 1, further comprising a reverse holding blade arranged opposite the upper blade on the lower surface side of the material to be cut. The cutting device according to claim 2, wherein the reverse blade is movable in the vertical direction. The cutting device according to claim 3, wherein the reverse holding blade is attached to a die cushion. A cutting device according to any one of claims 1 to 4, wherein the cutting edge of the first blade forms an acute angle. When cutting a workpiece made of a plate-shaped resin material containing fibers,
Using the cutting device according to any one of claims 1 to 5,
With the workpiece sandwiched and fixed between the lower blade and the plate holder, the upper blade is moved from the upper surface side of the workpiece to the lower surface side of the workpiece;
A first step of shearing and cutting the workpiece with the first blade;
a second step of scraping off the structure of the end surface of the workpiece obtained in the first step with the second blade. The cutting method according to claim 6, wherein the material to be cut is carbon fiber reinforced plastic. The cutting device further includes a reverse holding blade disposed on the lower surface side of the workpiece so as to face the upper blade, and the reverse holding blade is movable in a vertical direction.
The first step is carried out in a state where the reverse pressing blade is raised,
The cutting method according to claim 6 or 7, wherein the second step is performed in a state in which the reverse presser blade is lowered further than in the first step.

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