A bevel method for PCB based on thickness compensation
Patent Information
- Application Number
- CN202610905168.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-06-23
- Publication Date
- 2026-09-11
AI Technical Summary
[0007]本发明的目的在于提供一种基于厚度补偿的PCB板斜边方法，以解决上述背景技术中提出的在多片式PCB板的斜边过程中，刀具位置不能根据每个PCB板的厚度进行调节，金手指区斜边倒角切割时会产生误差的问题
本发明在运行过程中，通过上夹块的位移传感器实时获取每个PCB板的厚度，并根据厚度计算出每个单板对应的中间层高度，以此调整刀具平台的高度，确保刀具平台上的两个切刀与PCB板金手指区的中间层之间的距离相等，以使得两个切刀在对PCB板金手指区斜边倒角时，切削量相同，切削后的PCB板金手指区两侧对称，实现了基于厚度补偿的对称倒角切割，有效消除了因各单板厚度差异导致的加工误差，显著降低了废品率；利用成像镜头自动识别金手指的精确位置与轮廓，生成准确的进给路径，保证倒角形状和位置的一致性，提高了加工精度；采用撑板机构配合送板机构使 PCB 板平稳进入夹具，避免了薄板因下垂产生的送料不到位或损伤，提升了多片排版式 PCB 板连续加工的稳定性和效率；整个流程从上料、厚度测量、视觉定位到倒角切割和复位均自动完成，适应性强，特别适合多片排版式 PCB 板的高效、高精度斜边加工需求。
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Figure CN122742268A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of beveling machine technology, and in particular to a beveling method for PCB boards based on thickness compensation. Background Technology
[0002] In the PCB manufacturing process, multiple long strips of PCBs are typically processed from a large PCB blank, and then cut into their respective shapes. A crucial step during this process is the beveling and chamfering of the edges of the gold finger area on the PCB.
[0003] Typically, before beveling PCB boards in large quantities, a small-batch trial production is conducted. The beveling machine's cutters are adjusted by repeatedly cutting based on experience data. After the adjustment, the beveling-treated PCB boards pass inspection and acceptance before mass production of PCB boards.
[0004] However, the beveling operation described above is a standardized process that ignores differences in PCB board blanks. In reality, during the beveling process, the thickness of each PCB board blank will have slight variations, and even different individual PCB boards from the same blank will have different thicknesses. Using the same beveling parameters to beveling PCB board blanks will result in different quality edges on the gold fingers of individual PCB boards after beveling, meaning poor quality consistency among individual PCB boards. If the blanks are from different batches of the same specification, the thickness difference will be even greater, and the consistency after beveling will be even worse.
[0005] If the PCB boards are of different specifications, the beveling machine must be recalibrated before the beveling process, which leads to a decrease in production efficiency.
[0006] Currently, there is no method for compensating for the bevel of the cutting tool based on the thickness of the PCB board blank. Summary of the Invention
[0007] The purpose of this invention is to provide a PCB board beveling method based on thickness compensation, in order to solve the problem mentioned in the background art that the tool position cannot be adjusted according to the thickness of each PCB board during the beveling process of multi-piece PCB boards, and errors will occur when beveling the gold finger area.
[0008] To achieve the above objectives, the present invention provides the following technical solution: A thickness-compensated PCB beveling method is applied to a multi-piece PCB beveling machine. The multi-piece PCB beveling machine includes a feeding device, a fixture, a cutting platform, and an imaging lens. The fixture includes an upper clamping block and a lower clamping block. The imaging lens is positioned above and outside the fixture to identify the gold finger area on a single PCB piece within the PCB blank held by the fixture. The method includes the following steps: S1. Obtain the height H0 of the lower clamping block and keep the lower clamping block fixed. Control the upper clamping block to move downward and make direct contact with the lower clamping block, thereby obtaining the downward stroke L0 of the upper clamping block. S2. The feeding device obtains the PCB board blank and transports the gold finger area of the nth PCB board on the PCB board blank to the upper and lower clamping blocks of the fixture. The edge of the gold finger area protrudes from the fixture to facilitate bevel cutting. S3. Control the upper clamping block to move downward and clamp the nth PCB board together with the lower clamping block. Then obtain the downward stroke Ln of the upper clamping block, calculate the thickness of the nth PCB board according to L0-Ln, and further calculate the height of the middle layer of the gold finger area of the nth PCB board according to H0+(L0-Ln) / 2. S4. The imaging lens images the gold finger area of the nth PCB board downwards, identifies the gold finger area, and determines the fitted coordinates (Xn1, Yn) and (Xn2, Yn) of the two endpoints of the edge of the gold finger area. S5. Adjust the center of the tool platform to H0+(L0-Ln) / 2 height to align with the middle layer of the gold finger area of the nth PCB board. Then, determine the infeed path and the bevel path based on the fitted coordinates (Xn1, Yn) and (Xn2, Yn) of the two endpoints of the edge of the gold finger area and the bevel angle γ. S6. After the bevel is completed, control the tool platform to open and reset the tool, and then repeat steps S2-S5.
[0009] Furthermore, in step S1, a displacement sensor is provided on the upper clamping block or the driving mechanism of the upper clamping block to detect the downward stroke L0 of the upper clamping block.
[0010] Furthermore, in step S1, the height H0 of the lower clamping block refers to the height of the upper clamping surface of the lower clamping block. This height can be obtained by measurement or by calculation based on the downward stroke L0 of the upper clamping block and the displacement sensor on the upper clamping block.
[0011] Further, in step S1, when the downward stroke L0 of the upper clamping block is obtained, the motor torque T of the upper clamping block drive mechanism or the pressure F between the upper clamping block and the lower clamping block is obtained; when the torque T reaches the threshold T0, or the pressure F reaches the threshold F0, the upper clamping block stops, and the stroke corresponding to the position where the upper clamping block stops is the downward stroke L0; correspondingly, when the downward stroke Ln of the upper clamping block is obtained, the torque T uses the same threshold T0 and the pressure F uses the same threshold F0.
[0012] Further, in step S2, the feeding device includes a board feeding mechanism and a support plate mechanism. The support plate mechanism includes a lifting plate, wherein the clamping surface height of the board feeding mechanism is level with the height of the lower clamping block of the fixture. The lifting plate has two working states: when the lifting plate is in the first working state, the height of the lifting plate is equal to the clamping height of the board feeding mechanism; when the lifting plate is in the second working state, the height of the lifting plate is higher than the clamping height of the board feeding mechanism, so that the PCB board as a whole passes over the lower clamping block in an inclined state. Correspondingly, in step S2, during the process of conveying the gold finger area of the nth PCB board on the PCB board blank to between the upper clamping block and the lower clamping block, the upper clamping block is controlled to be in the open state, and then the lifting plate is controlled to be in the second working state. When the PCB board blank is conveyed to the position, the lifting plate is first controlled to return to the first working state, and then the upper clamping block is controlled to move down and clamp the PCB board blank together with the lower clamping block.
[0013] Furthermore, the board feeding mechanism includes a positioning clamp, a support base, and a transmission component. The positioning clamp and the support base cooperate to clamp one end of the PCB board, and the transmission component can drive the positioning clamp and the support base to move back and forth simultaneously in the clamping direction.
[0014] Furthermore, after the beveled edges of all gold finger areas on the PCB blank are completed, step S7 is also included: opening the upper clamping block and controlling the lifting plate to rise to the second working state, and then driving the board feeding mechanism to retract the PCB blank; after replacing the new PCB blank, steps S2-S6 are executed again.
[0015] Further, in step S4, determining the fitted coordinates (Xn1, Yn) and (Xn2, Yn) of the two endpoints of the gold finger area edge includes: first performing linear fitting on the identified gold finger area edge, determining whether the fitted gold finger area line is parallel to the X-axis, if parallel, taking the values of the two endpoints as the fitted coordinates, and if not parallel, stopping the alarm.
[0016] Furthermore, in step S5, the tool platform includes a mounting plate capable of horizontal and vertical displacement. Rotatable fixing blocks are symmetrically arranged on the outer side of the mounting plate, and cutting blades are respectively arranged on the fixing blocks. A linkage mechanism is provided between the two fixing blocks, and the fixing blocks can rotate synchronously through the linkage mechanism. When the fixing blocks rotate, the two cutting blades move closer or further apart.
[0017] Compared with the prior art, the beneficial effects of the present invention are: During operation, this invention uses a displacement sensor on the upper clamping block to acquire the thickness of each PCB board in real time. Based on the thickness, the height of the intermediate layer corresponding to each board is calculated, and the height of the tool platform is adjusted accordingly. This ensures that the distance between the two cutters on the tool platform and the intermediate layer of the PCB board's gold finger area is equal, resulting in identical cutting amounts when chamfering the beveled edges of the PCB board's gold finger area. The resulting symmetrical chamfering of the PCB board's gold finger area achieves thickness-compensated symmetrical chamfering, effectively eliminating processing errors caused by differences in the thickness of individual boards and significantly reducing the scrap rate. An imaging lens automatically identifies the precise position and contour of the gold fingers, generating an accurate feed path to ensure consistency in chamfer shape and position, improving processing accuracy. A support plate mechanism combined with a feeding mechanism ensures the PCB board smoothly enters the fixture, preventing incomplete feeding or damage caused by sagging of thin boards, thus improving the stability and efficiency of continuous processing of multi-panel PCBs. The entire process, from loading, thickness measurement, visual positioning to chamfering and resetting, is automatically completed, offering strong adaptability and making it particularly suitable for multi-panel PCBs. The need for efficient and high-precision bevel machining of boards. Attached Figure Description
[0018] Figure 1 This is a schematic diagram of the workflow of the present invention; Figure 2 This is a partial three-dimensional structural diagram of the system using this method; Figure 3 This is a partial three-dimensional structural diagram of the system using this method; Figure 4 for Figure 3 Enlarged view of point A in the image; Figure 5 for Figure 2 Enlarged view of point B in the image; Figure 6 for Figure 3 Enlarged view of point C in the image.
[0019] In the diagram: 100, feeding device; 110, plate feeding mechanism; 111, positioning clamp; 112, support base; 113, transmission assembly; 120, support plate mechanism; 121, lifting plate; 200. Fixture; 210. Upper clamping block; 211. Displacement sensor; 220. Lower clamping block; 300. Tool platform; 310. Mounting plate; 320. Fixing block; 330. Cutting blade; 350. Linkage mechanism; 400. Imaging lens. Detailed Implementation
[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0021] like Figures 1-4 As shown, the present invention provides a PCB board beveling method based on thickness compensation, which is applied to a multi-piece PCB board beveling machine. The multi-piece PCB board beveling machine includes a feeding device 100, a fixture 200, a tool platform 300, and an imaging lens 400. The feeding device 100 is used to feed PCB board blanks to the fixture 200, and the tool platform 300 is used to chamfer the gold finger area of the PCB board. The clamp 200 includes an upper clamping block 210 and a lower clamping block 220. The imaging lens 400 is positioned above the outside of the clamp 200 to identify the gold finger area on a single PCB in the PCB blank held by the clamp 200. The method includes the following steps: Step S1: Obtain the height H0 of the lower clamping block 220 and keep the lower clamping block 220 fixed. Control the upper clamping block 210 to move downward and make direct contact with the lower clamping block 220, thereby obtaining the downward stroke L0 of the upper clamping block 210.
[0022] A displacement sensor is provided on the upper clamping block 210 or the drive mechanism of the upper clamping block 210 to detect the downward stroke L0 of the upper clamping block.
[0023] The height H0 of the lower clamping block refers to the height of the upper clamping surface of the lower clamping block. This height can be obtained by measurement or by calculation based on the downward stroke L0 of the upper clamping block and the displacement sensor on the upper clamping block.
[0024] Step S2: The feeding device 100 obtains the PCB board blank and transports the gold finger area of the nth PCB board on the PCB board blank to the space between the upper clamping block 210 and the lower clamping block 220. The edge of the gold finger area protrudes from the clamping fixture 200 to facilitate bevel cutting. The imaging lens 400 can be used to determine whether the gold finger area of the PCB board has been delivered in place.
[0025] Step S3: Control the upper clamping block 210 to move downward and clamp the nth PCB board together with the lower clamping block 220. Then obtain the downward stroke Ln of the upper clamping block 210, calculate the thickness of the nth PCB board according to L0-Ln, and further calculate the height of the middle layer of the gold finger area of the nth PCB board according to H0+(L0-Ln) / 2. After obtaining the height of the middle layer of the gold finger area of the PCB board, the height that the corresponding tool platform needs to reach can be known. Step S4: The imaging lens 400 images the gold finger area of the nth PCB board downwards and identifies the gold finger area. It determines the fitted coordinates (Xn1, Yn) and (Xn2, Yn) of the two endpoints of the edge of the gold finger area. Through the two coordinate points (Xn1, Yn) and (Xn2, Yn), the starting point and ending point of the edge of the gold finger area can be known.
[0026] Step S5: Adjust the center of the tool platform 300 to H0+(L0-Ln) / 2 height to align with the middle layer of the gold finger area of the nth PCB board. Then, determine the infeed path and the bevel path based on the fitted coordinates (Xn1, Yn) and (Xn2, Yn) of the two endpoints of the edge of the gold finger area and the bevel angle γ.
[0027] Specifically, after obtaining the height of the middle layer of the PCB gold finger area, the center of the tool platform 300 is adjusted to the same height (ensuring that the distance between the two cutters of the tool platform and the middle layer of the PCB gold finger area is equal, so that the two cutters have the same cutting amount when chamfering the bevel of the PCB gold finger area, and the two sides of the PCB gold finger area are symmetrical after cutting), so as to achieve bevel chamfering based on thickness compensation for different PCB gold finger areas; Then, the start and end points of the bevel path are determined based on the fitted coordinates (Xn1, Yn) and (Xn2, Yn) of the two endpoints of the gold finger area. Next, the bevel path is determined based on the required bevel angle γ, which is usually set to 30-60°. The angle of the cutter is adjusted according to different angles to determine the bevel path. Then, the bevel operation is performed on the gold finger area of the PCB board according to the feed path and the bevel path to ensure that the bevel operation of the gold finger area of each PCB board is accurate.
[0028] Step S6: After the bevel is completed, control the tool platform 300 to open and reset the tool, and then repeat steps S2-S5.
[0029] Further, in step S1, when obtaining the downward stroke L0 of the upper clamping block 210, the motor torque T of the upper clamping block 210 drive mechanism or the pressure F between the upper clamping block 210 and the lower clamping block 220 is obtained; when the torque T reaches the threshold T0, or the pressure F reaches the threshold F0, the upper clamping block 210 stops, and the stroke corresponding to the stopping position of the upper clamping block 210 is the downward stroke L0; correspondingly, when obtaining the downward stroke Ln of the upper clamping block 210, the torque T uses the same threshold T0 and the pressure F uses the same threshold F0. When the upper clamping block 210 moves downward, the pressure applied to the lower clamping block or PCB board is kept the same during the downward process, which will not affect the calculation of the downward stroke L0 and Ln.
[0030] Further, in step S2, the loading device 100 includes a board feeding mechanism 110 and a support plate mechanism 120. The support plate mechanism 120 includes a lifting plate 121. The height of the clamping surface of the board feeding mechanism 110 is the same as the height of the lower clamping block 220 of the fixture 200. The lifting plate 121 has two working states: when the lifting plate 121 is in the first working state, the height of the lifting plate 121 is equal to the clamping height of the board feeding mechanism 110; when the lifting plate 121 is in the second working state, the height of the lifting plate 121 is higher than the clamping height of the board feeding mechanism 110, so that the PCB board as a whole passes over the lower clamping block 220 in an inclined state. Correspondingly, in step S2, when the feeding mechanism 100 feeds the PCB blank to the fixture 200, one end of the PCB blank is clamped by the board feeding mechanism 110, and the other end of the PCB blank is supported by the support plate mechanism 120. During the feeding process to the fixture 200, firstly, the lifting plate 121 is in the first working state, that is, the height of the lifting plate 121 is the same as the height of the lower clamping block 220. When the PCB blank is conveyed above the lifting plate 121, the lifting plate 121 is controlled to switch to the second working state. At this time, the height of the lifting plate 121 is higher than the height of the board feeding mechanism 110. The board feeding mechanism 110 continues to move to drive the PCB blank into the fixture 200. At this time, the PCB blank is in an inclined state, passing over the lower clamping block 220, which can avoid the lower clamping block 220 scratching the PCB. When the PCB blank is conveyed to the position, the lifting plate 121 is controlled to return to the first working state, and then the upper clamping block 210 is controlled to move down and clamp the nth PCB in the PCB blank together with the lower clamping block 220.
[0031] Furthermore, the board feeding mechanism 110 includes a positioning clamp 111, a support base 112, and a transmission assembly 113. The positioning clamp 111 and the support base 112 cooperate to clamp one end of the PCB board. The transmission assembly 113 can drive the positioning clamp 111 and the support base 112 to move back and forth in the direction of the fixture 200 at the same time. When the transmission assembly 113 drives the positioning clamp 111 and the support base 112 to move towards the fixture 200, the PCB board blank can be fed into the fixture 200.
[0032] Furthermore, after all the beveled edges of the gold finger areas on the PCB blank are completed, step S7 is also included: opening the upper clamping block 210 and then controlling the lifting plate 121 to rise to the second working state, and then driving the board feeding mechanism 110 to retract the PCB blank; after the processed PCB blank is taken away, after replacing it with a new PCB blank, steps S2-S6 are executed again.
[0033] Further, in step S4, determining the fitted coordinates (Xn1, Yn) and (Xn1, Yn) of the two endpoints of the gold finger area edge includes: first, performing linear fitting on the identified gold finger area edge, and determining whether the fitted gold finger area line is parallel to the X-axis. If it is parallel, the values of the two endpoints are taken as the fitted coordinates; if it is not parallel, the machine stops and an alarm is triggered. If the fitted gold finger area line is not parallel to the X-axis, it indicates that the gold finger area is in a skewed state or is damaged and cannot continue to work. The machine stops and an alarm is triggered to inform the staff.
[0034] Furthermore, in step S5, the tool platform 300 includes a mounting plate 310 capable of horizontal and vertical displacement. The outer side of the mounting plate 310 is symmetrically provided with rotatable fixing blocks 320, and each fixing block 320 is provided with a cutting blade 330. A linkage mechanism 350 is provided between the two fixing blocks 320. The fixing blocks 320 can rotate synchronously through the linkage mechanism 350. When the fixing blocks 320 rotate, the two cutting blades 330 move closer or further apart. By rotating the fixing blocks 320, the cutting angle of the two cutting blades 330 can be controlled synchronously.
[0035] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A PCB board beveling method based on thickness compensation, applied to a multi-piece PCB board beveling machine, the multi-piece PCB board beveling machine comprising a feeding device (100), a fixture (200), a tool platform (300), and an imaging lens (400); the fixture (200) comprises an upper clamping block (210) and a lower clamping block (220), and the imaging lens (400) is positioned above the outside of the fixture (200) to identify the gold finger area on a single PCB board in the PCB board blank held by the fixture (200); characterized in that, The method includes the following steps: S1. Obtain the height H0 of the lower clamping block (220) and keep the lower clamping block (220) fixed. Control the upper clamping block (210) to move downward and make direct contact with the lower clamping block (220), thereby obtaining the downward stroke L0 of the upper clamping block (210). S2. The feeding device (100) obtains the PCB board blank and transports the gold finger area of the nth PCB board on the PCB board blank to the upper clamping block (210) and lower clamping block (220) of the fixture (200). The edge of the gold finger area protrudes from the fixture (200) to facilitate bevel cutting. S3. Control the upper clamping block (210) to move downward and clamp the nth PCB board together with the lower clamping block (220). Then obtain the downward stroke Ln of the upper clamping block (210), calculate the thickness of the nth PCB board according to L0-Ln, and further calculate the height of the middle layer of the gold finger area of the nth PCB board according to H0+(L0-Ln) / 2. S4. The imaging lens (400) images the gold finger area of the nth PCB board downwards, identifies the gold finger area, and determines the fitted coordinates (Xn1, Yn) and (Xn2, Yn) of the two endpoints of the edge of the gold finger area. S5. Adjust the center of the tool platform (300) to H0+(L0-Ln) / 2 height to align with the middle layer of the gold finger area of the nth PCB board. Then determine the infeed path and the bevel path based on the fitted coordinates (Xn1, Yn) and (Xn2, Yn) of the two endpoints of the edge of the gold finger area and the bevel angle γ. S6. After the bevel is completed, control the tool platform (300) to open and reset the tool, and then repeat steps S2-S5.
2. The PCB board bevel method based on thickness compensation according to claim 1, characterized in that, In step S1, a displacement sensor (211) is provided on the upper clamping block (210) or the driving mechanism of the upper clamping block (210) to detect the downward stroke L0 of the upper clamping block (210).
3. The PCB board bevel method based on thickness compensation according to claim 1, characterized in that, In step S1, the height H0 of the lower clamping block (220) refers to the height of the upper clamping surface of the lower clamping block (220). This height can be obtained by measurement or by calculation based on the downward stroke L0 of the upper clamping block (210) and the displacement sensor (211) on the upper clamping block (210).
4. The PCB board bevel method based on thickness compensation according to claim 1, characterized in that, In step S1, when the downward stroke L0 of the upper clamping block (210) is obtained, the motor torque T of the upper clamping block (210) drive mechanism or the pressure F between the upper clamping block (210) and the lower clamping block (220) is obtained; when the torque T reaches the threshold T0, or the pressure F reaches the threshold F0, the upper clamping block (210) stops, and the stroke corresponding to the position where the upper clamping block (210) stops is the downward stroke L0; correspondingly, when the downward stroke Ln of the upper clamping block (210) is obtained, the torque T uses the same threshold T0 and the pressure F uses the same threshold F0.
5. The PCB board bevel method based on thickness compensation according to claim 1, characterized in that, In step S2, the feeding device (100) includes a feeding mechanism (110) and a support mechanism (120). The support mechanism (120) includes a lifting plate (121). The height of the clamping surface of the feeding mechanism (110) is equal to the height of the lower clamping block (220) of the fixture (200). The lifting plate (121) has two working states: when the lifting plate (121) is in the first working state, the height of the lifting plate (121) is equal to the clamping height of the feeding mechanism (110); when the lifting plate (121) is in the second working state, the height of the lifting plate (121) is higher than the feeding surface. The clamping height of the board mechanism (110) allows the PCB board to pass over the lower clamping block (220) in an inclined state. Correspondingly, in step S2, during the process of transporting the gold finger area of the nth PCB board on the PCB board blank to between the upper clamping block (210) and the lower clamping block (220), the upper clamping block (210) is controlled to be in the open state, and then the lifting plate (121) is controlled to be in the second working state. When the PCB board blank is transported to the position, the lifting plate (121) is first controlled to return to the first working state, and then the upper clamping block (210) is controlled to move down and clamp the PCB board blank together with the lower clamping block (220).
6. The PCB board bevel method based on thickness compensation according to claim 5, characterized in that, The board feeding mechanism (110) includes a positioning clamp (111), a support base (112), and a transmission component (113). The positioning clamp (111) and the support base (112) cooperate to clamp one end of the PCB board. The transmission component (113) can drive the positioning clamp (111) and the support base (112) to move back and forth in the direction of the clamp (200) at the same time.
7. The PCB board bevel method based on thickness compensation according to claim 1, characterized in that, After all the beveled edges of the gold finger area on the PCB blank are completed, step S7 is also included: open the upper clamping block (210) and then control the lifting plate (121) to rise to the second working state, and then drive the board feeding mechanism (110) to retract the PCB blank; after replacing the new PCB blank, steps S2-S6 are executed again.
8. The PCB board bevel method based on thickness compensation according to claim 1, characterized in that, In step S4, determining the fitted coordinates (Xn1, Yn) and (Xn2, Yn) of the two endpoints of the edge of the gold finger area includes: first, performing linear fitting on the edge of the identified gold finger area, and determining whether the straight line of the fitted gold finger area is parallel to the X-axis. If it is parallel, the values of the two endpoints are taken as the fitted coordinates; if it is not parallel, the machine stops and an alarm is triggered.
9. The PCB board bevel method based on thickness compensation according to claim 1, characterized in that, In step S5, the tool platform (300) includes a mounting plate (310) capable of horizontal and vertical displacement. The mounting plate (310) is symmetrically provided with rotating fixing blocks (320) on its outer side. Each fixing block (320) is provided with a cutting blade (330). A linkage mechanism (350) is provided between the two fixing blocks (320). The fixing blocks (320) can rotate synchronously through the linkage mechanism (350). When the fixing blocks (320) rotate, the two cutting blades (330) move closer or further apart.