Polishing device for longitudinal cutting blade processing
Patent Information
- Application Number
- CN202522583001.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-05
- Publication Date
- 2026-10-27
- Estimated Expiration
- 2035-12-05
AI Technical Summary
[0007]通过采用上述技术方案,解决了现有纵剪刀片打磨设备只能够打磨一种内孔直径尺寸的纵剪刀片的技术问题,当需要加工打磨内壁尺寸大于传动辊外径的刀片时,设备人员仅需将固定辊固定套设在传动辊的外壁上,固定辊内壁上的半圆形的卡柱与传动辊外壁上的凹槽进行镶嵌配合,使得传动辊发生转动时能够带动固定辊实现同步旋转,固定辊的外壁尺寸大于传动辊的外壁尺寸,使得转杆能够带动内壁尺寸更大的刀片进行旋转,从而使打磨机能够打磨两种内孔直径尺寸不相同的刀片
[0025]1、本实用新型通过设置打磨机、转杆、传动辊、固定辊、第一固定盘和第二固定盘,解决了现有纵剪刀片打磨设备只能够打磨一种内孔直径尺寸的纵剪刀片的技术问题,当需要加工打磨内壁尺寸大于传动辊外径的刀片时,设备人员仅需将固定辊固定套设在传动辊的外壁上,固定辊内壁上的半圆形的卡柱与传动辊外壁上的凹槽进行镶嵌配合,使得传动辊发生转动时能够带动固定辊实现同步旋转,固定辊的外壁尺寸大于传动辊的外壁尺寸,使得转杆能够带动内壁尺寸更大的刀片进行旋转,从而使打磨机能够打磨两种内孔直径尺寸不相同的刀片。
Smart Images

Figure CN224896674U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of blade processing, specifically a grinding device for processing longitudinal shear blades. Background Technology
[0002] The longitudinal shear blade is the core cutting component of a longitudinal slitting machine. It is usually a disc-shaped hard structure, mostly made of wear-resistant hard alloys such as tungsten steel. It is mainly used for slitting metal coils and can accurately divide wide coils into narrow strips of a specified width. Its cutting edge accuracy and wall flatness directly determine the cut quality of the slitting products.
[0003] Currently, the processing and grinding of longitudinal shear blades mainly relies on specialized grinding machines. During operation, several longitudinal shear blades need to be stacked and fixed on the drive roller of the grinding machine according to specifications. The drive roller drives the blade assembly to rotate at high speed, while the grinding wheel grinding mechanism of the grinding machine feeds towards the blade wall. By means of the relative grinding motion between the grinding wheel and the rotating blade, the sharpness of the cutting edge or the calibration of the wall surface processing accuracy is completed.
[0004] The drive roller diameter of existing grinding equipment is mostly fixed and can only be used to fit slitting blades with a specific inner diameter. When it is necessary to process slitting blades with other inner diameters, it is not possible to adjust the drive roller to fit the new blade specifications. Instead, a roller of the corresponding size must be replaced or other special equipment must be used, which increases processing costs and reduces the efficiency of production changeover. Utility Model Content
[0005] Therefore, the purpose of this utility model is to provide a grinding device for processing longitudinal shear blades, so as to solve the technical problems mentioned in the background art.
[0006] To achieve the above objectives, this utility model provides the following technical solution: a grinding device for processing longitudinal shear blades, including a grinding machine, a rotating rod provided on one side of the grinding machine, a transmission roller fixed to the outer wall of the rotating rod, a first limiting strip fixedly installed on the outer wall of the transmission roller, five sets of grooves opened on the outer wall of the transmission roller, a fixed roller movably installed on the outer wall of the transmission roller, five sets of locking pins fixed on the inner wall of the fixed roller, a locking groove opened on the inner wall of the fixed roller, a second limiting strip fixed on the outer wall of the fixed roller, a blade sleeved on the outer wall of the fixed roller, and a driven box provided at one end of the rotating rod.
[0007] By adopting the above technical solution, the technical problem that existing longitudinal shear blade grinding equipment can only grind longitudinal shear blades with one inner diameter size is solved. When it is necessary to process and grind blades with an inner wall size larger than the outer diameter of the drive roller, the equipment operator only needs to fix the fixed roller on the outer wall of the drive roller. The semi-circular locking post on the inner wall of the fixed roller is fitted with the groove on the outer wall of the drive roller, so that when the drive roller rotates, it can drive the fixed roller to rotate synchronously. The outer wall size of the fixed roller is larger than that of the drive roller, so that the rotating rod can drive the blade with a larger inner wall size to rotate, thereby enabling the grinder to grind two blades with different inner diameter sizes.
[0008] The present invention is further configured such that a servo motor is installed on the top of the grinder, a drive wheel is fixed to one end of the servo motor, a toothed belt is sleeved on the outer wall of the drive wheel, a transmission wheel is provided on the outer wall of the grinder, and a reduction mechanism is provided inside the grinder. The two ends of the reduction mechanism inside the grinder are respectively connected to the rotating rod and the transmission wheel.
[0009] Preferably, the servo motor provides power to the grinder, and the reduction mechanism inside the grinder reduces the speed transmitted by the servo motor, so that the rotating rod can rotate at the set speed.
[0010] The present invention is further configured such that a retaining ring is fixed at one end of the transmission roller, a first fixing plate is installed on one side of the transmission roller, and the outer diameter of the first limiting strip and the transmission roller matches the inner wall size of the blade with a small inner hole diameter.
[0011] Preferably, after multiple sets of blades with small inner diameter are installed on the outer wall of the transmission roller, the first fixing disc and the retaining ring cooperate to squeeze and fix the blades.
[0012] The present invention is further configured such that the locking post is semi-circular, and the shape and size of the groove match the locking post.
[0013] Preferably, when the fixed roller is sleeved on the outer wall of the transmission roller, the semi-circular locking post on the inner wall of the fixed roller is fitted into the groove on the outer wall of the transmission roller, so that the friction between the fixed roller and the transmission roller is greater than the friction between the blade and the fixed roller.
[0014] The present invention is further configured such that the outer diameter of the second limiting strip and the fixing roller matches the inner wall size of the blade with a large inner diameter, and a second fixing plate is installed at one end of the fixing roller, and the outer diameter of the second fixing plate is larger than the outer diameter of the blade with a large inner diameter.
[0015] Preferably, the second fixed disc is fixedly installed on the outer wall of the drive roller and the fixed roller by bolts, so that the second fixed disc can squeeze and fix the multiple sets of blades sleeved on the outer wall of the fixed roller.
[0016] The present invention is further configured such that the inner walls of both the first fixing plate and the second fixing plate are provided with perforations.
[0017] Preferably, when the first fixed disc is fitted onto the outer wall of the rotating rod, the perforation with a wall surface size larger than the wall surface size of the protrusion allows the first fixed disc to pass through the protrusion.
[0018] The present invention is further configured such that bolt holes are provided on the outer walls of one end of the transmission roller and the fixed roller, and multiple sets of mounting holes are provided inside the first fixed plate and the second fixed plate.
[0019] Preferably, the mounting holes on the first and second fixed disks correspond to the bolt holes on the outer walls of the drive roller and the fixed roller, respectively, so that the first and second fixed disks can be fixedly mounted on one end of the outer wall of the drive roller and the fixed roller by bolts.
[0020] The present invention is further configured such that a driving block and two sets of sliders are fixed at the bottom of the driven box, and a lead screw and a limiting rod are respectively installed through the interior of the driving block and the sliders, and a stepper motor is installed at one end of the lead screw.
[0021] Preferably, the equipment operator controls the stepper motor through the grinding equipment control box. The stepper motor drives the drive block fixedly installed at the bottom of the driven box through the lead screw, so that the driven box moves horizontally away from the rotating rod, and the support bearing assembly on one side of the driven box disengages from the end of the rotating rod.
[0022] The present invention is further configured such that a protrusion is fixed at one end of the outer wall of the rotating rod, and a support bearing assembly is installed on one side of the driven box, and the inner wall shape and size of the support bearing assembly are matched with one end of the rotating rod.
[0023] Preferably, the support bearing assembly on the driven box side supports the rotating rod, enabling the rotating rod to rotate stably.
[0024] In summary, the present invention has the following main advantages:
[0025] 1. This utility model solves the technical problem that existing longitudinal shear blade grinding equipment can only grind longitudinal shear blades with one inner diameter by setting up a grinding machine, a rotating rod, a transmission roller, a fixed roller, a first fixed plate, and a second fixed plate. When it is necessary to process and grind blades with an inner wall size larger than the outer diameter of the transmission roller, the equipment operator only needs to fix the fixed roller on the outer wall of the transmission roller. The semi-circular locking post on the inner wall of the fixed roller is fitted with the groove on the outer wall of the transmission roller, so that when the transmission roller rotates, it can drive the fixed roller to rotate synchronously. The outer wall size of the fixed roller is larger than that of the transmission roller, so that the rotating rod can drive the blade with a larger inner wall size to rotate, thereby enabling the grinding machine to grind two blades with different inner diameters.
[0026] 2. This utility model, by setting a first limiting strip, a second limiting strip, a fixed roller, a locking post, a locking groove, and a recess, has a semi-circular locking post on the inner wall of the fixed roller and a recess on the outer wall of the transmission roller that are interlocked. Multiple sets of blades are sleeved on the outer wall of the fixed roller, and the cuts on their inner walls are interlocked with the second limiting strip on the outer wall of the fixed roller. There are gaps between the interlocking parts, while the interlocking parts are tightly fitted. When the equipment personnel remove the blades sleeved on the outer wall of the fixed roller, the friction between the blades and the fixed roller is much less than the friction between the fixed roller and the transmission roller, so the fixed roller will be firmly and tightly fitted to the transmission roller and will not slip. Attached Figure Description
[0027] Figure 1 This is a schematic diagram of the overall device of this utility model;
[0028] Figure 2 This is a schematic diagram of the separation of the driven box according to this utility model;
[0029] Figure 3 This is a schematic diagram of the rotating rod connection of this utility model;
[0030] Figure 4 This is a schematic diagram of the blade installation of this utility model;
[0031] Figure 5 This is a schematic diagram of the first fixing plate of this utility model;
[0032] Figure 6 This is a structural diagram of the transmission roller of this utility model;
[0033] Figure 7 This is a structural diagram of the fixed roller of this utility model;
[0034] Figure 8 This is a schematic diagram of the fixed roller sleeve of this utility model;
[0035] Figure 9 This is a schematic diagram of the second fixing plate of this utility model;
[0036] Figure 10 This is a schematic diagram of the installation of the fixing column of this utility model;
[0037] Figure 11 This is a structural diagram of the first and second fixed disks of this utility model.
[0038] Explanation of reference numerals in the attached figures:
[0039] 1. Grinding machine; 101. Transmission wheel; 102. Toothed belt; 103. Drive wheel; 104. Servo motor; 2. Rotating rod; 201. Protrusion; 202. Transmission roller; 203. First limiting bar; 204. Groove; 205. Bolt hole; 206. Retaining ring; 207. Fixing post; 3. Blade; 4. First fixing plate; 401. Second fixing plate; 402. Mounting hole; 403. Through hole; 404. Insertion hole; 5. Driven box; 501. Slider; 502. Drive block; 503. Limiting rod; 504. Lead screw; 505. Stepper motor; 6. Fixing roller; 601. Clamping post; 602. Clamping groove; 603. Second limiting bar. Detailed Implementation
[0040] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.
[0041] The embodiments of this utility model will be described below based on its overall structure.
[0042] First embodiment: Please refer to Figure 1 — Figure 9The system includes a grinder 1, a rotating rod 2 on one side of the grinder 1, a transmission roller 202 fixed to the outer wall of the rotating rod 2, a first limiting strip 203 fixedly installed on the outer wall of the transmission roller 202, five sets of grooves 204 formed on the outer wall of the transmission roller 202, a fixed roller 6 movably installed on the outer wall of the transmission roller 202, five sets of locking pins 601 fixed to the inner wall of the fixed roller 6, a locking groove 602 formed on the inner wall of the fixed roller 6, a second limiting strip 603 fixed to the outer wall of the fixed roller 6, and a blade 3 sleeved on the outer wall of the fixed roller 6. A driven box 5 is provided at one end of the rotating rod 2. This system solves the problem that existing longitudinal shear blade grinding equipment can only grind one type of inner diameter ruler. Regarding the technical issue of the slitting blade, when it is necessary to process and grind blades 3 with an inner wall size larger than the outer diameter of the transmission roller, the equipment operator only needs to fix the fixed roller 6 on the outer wall of the transmission roller 202. The semi-circular locking post 601 on the inner wall of the fixed roller 6 is fitted with the groove 204 on the outer wall of the transmission roller 202, so that when the transmission roller 202 rotates, it can drive the fixed roller 6 to rotate synchronously. The outer wall size of the fixed roller 6 is larger than the outer wall size of the transmission roller 202, so that the rotating rod 2 can drive the blade 3 with a larger inner wall size to rotate, thereby enabling the grinder 1 to grind two blades 3 with different inner hole diameters.
[0043] For details regarding the above embodiments, please refer to [link / reference]. Figure 2 A servo motor 104 is mounted on the top of the grinder 1. A drive wheel 103 is fixed to one end of the servo motor 104. A toothed belt 102 is fitted on the outer wall of the drive wheel 103. A transmission wheel 101 is provided on the outer wall of the grinder 1. A reduction mechanism is provided inside the grinder 1. The two ends of the reduction mechanism inside the grinder 1 are connected to the rotating rod 2 and the transmission wheel 101, respectively. The servo motor 104 provides power to the grinder 1, and the reduction mechanism inside the grinder 1 reduces the speed transmitted by the servo motor 104, so that the rotating rod 2 can rotate at the set speed.
[0044] For details regarding the above embodiments, please refer to [link / reference]. Figure 4 and Figure 5 One end of the transmission roller 202 is fixed with a retaining ring 206, and a first fixing plate 4 is installed on one side of the transmission roller 202. The outer diameter of the first limiting strip 203 and the transmission roller 202 are matched with the inner wall size of the blade 3 with a small inner diameter. When multiple sets of blades 3 with small inner diameter are installed on the outer wall of the transmission roller 202, the first fixing plate 4 and the retaining ring 206 cooperate to squeeze and fix the blades 3.
[0045] For details regarding the above embodiments, please refer to [link / reference]. Figure 6 and Figure 7The locking post 601 is set as a semi-circular shape, and the shape and size of the groove 204 match the locking post 601. When the fixed roller 6 is sleeved on the outer wall of the transmission roller 202, the semi-circular locking post 601 on the inner wall of the fixed roller 6 is fitted with the groove 204 on the outer wall of the transmission roller 202, so that the friction between the fixed roller 202 and the transmission roller 6 is greater than the friction between the blade 3 and the fixed roller 6.
[0046] For details regarding the above embodiments, please refer to [link / reference]. Figure 9 and Figure 10 The outer diameter of the second limiting strip 603 and the fixed roller 6 matches the inner wall size of the blade 3 with a large inner diameter. A second fixing plate 401 is installed at one end of the fixed roller 6, and the outer diameter of the second fixing plate 401 is larger than the outer diameter of the blade 3 with a large inner diameter. The second fixing plate 401 is fixedly installed on the outer wall of the transmission roller 202 and the end of the fixed roller 6 by bolts, so that the second fixing plate 401 squeezes and fixes the multiple sets of blades 3 sleeved on the outer wall of the fixed roller 6.
[0047] For details regarding the above embodiments, please refer to [link / reference]. Figure 5 and Figure 9 Both the inner walls of the first fixed plate 4 and the second fixed plate 401 are provided with through holes 403. When the first fixed plate 4 is fitted onto the outer wall of the rotating rod 2, the through holes 403, whose wall size is larger than the wall size of the protrusion 201, allow the first fixed plate 4 to pass through the protrusion 201.
[0048] For details regarding the above embodiments, please refer to [link / reference]. Figure 5 , Figure 8 and Figure 9 Bolt holes 205 are provided on the outer walls of both the drive roller 202 and the fixed roller 6 at one end. Multiple sets of mounting holes 402 are provided inside the first fixed plate 4 and the second fixed plate 401. The mounting holes 402 on the first fixed plate 4 and the second fixed plate 401 correspond to the bolt holes 205 on the outer walls of the drive roller 202 and the fixed roller 6, respectively, so that the first fixed plate 4 and the second fixed plate 401 can be fixedly installed on the outer walls of one end of the drive roller 202 and the fixed roller 6 by bolts.
[0049] For details regarding the above embodiments, please refer to [link / reference]. Figure 2 The driven box 5 has a drive block 502 and two sets of sliders 501 fixed at the bottom. The drive block 502 and sliders 501 are respectively installed with a lead screw 504 and a limit rod 503. A stepper motor 505 is installed at one end of the lead screw 504. The equipment operator controls the stepper motor 505 through the grinding equipment control box. The stepper motor 505 drives the drive block 502 fixed at the bottom of the driven box 5 through the lead screw 504, so that the driven box 5 moves horizontally away from the rotating rod 2. The support bearing assembly on one side of the driven box 5 disengages from the end of the rotating rod 2.
[0050] For details regarding the above embodiments, please refer to [link / reference]. Figure 2 One end of the outer wall of the rotating rod 2 is fixed with a protrusion 201. A support bearing assembly is installed on one side of the driven box 5, and the inner wall shape and size of the support bearing assembly match one end of the rotating rod 2. The support bearing assembly on one side of the driven box 5 supports the rotating rod 2, so that the rotating rod 2 can rotate stably.
[0051] Second embodiment: Please refer to Figure 10 and Figure 11 A fixing post 207 is fixed to the outer wall of one end of the transmission roller 202. The inner walls of the first fixing plate 4 and the second fixing plate 401 are both provided with insertion holes 404. When the equipment personnel put the first fixing plate 4 on the outer wall of the rotating rod 2, the first fixing plate 4 can be rotated so that the fixing post 207 on the outer wall of the transmission roller 202 is inserted into the insertion hole 404 on the inner wall of the first fixing plate 4. The transmission roller 2 limits and fixes the first fixing plate 4 through the fixing post 207 to prevent the first fixing plate 4 from rotating when the equipment personnel use bolts to fix the first fixing plate 4.
[0052] In practical operation, when it is necessary to grind the blades 3 whose inner diameter is equal to the outer diameter of the transmission roller 202, the operator first controls the stepper motor 505 through the grinding equipment control box. The stepper motor 505 drives the drive block 502 fixedly installed at the bottom of the driven box 5 through the lead screw 504, causing the driven box 5 to move horizontally away from the rotating rod 2. The support bearing assembly on one side of the driven box 5 disengages from the end of the rotating rod 2. Then, the operator places multiple sets of blades 3 onto the transmission roller 202. The notch on the inner wall of the transmission roller 202 is fitted into the first limiting strip 203 on the outer wall of the transmission roller 202. After the blades 3 are fully fitted on the outer wall of the transmission roller 202, the equipment operator then fixes the first fixing plate 4 to the outer wall of the end of the transmission roller 202 with bolts, so that the first fixing plate 4 presses and fixes the multiple sets of blades 3 fitted on the outer wall of the transmission roller 202. Finally, the stepper motor 505 drives the driven box 5 to move towards the transmission roller 202 in the opposite direction through the lead screw 504, so that the end of the rotating rod 2 is inserted into the interior of the driven box 2.
[0053] When grinding blades 3 with inner diameters larger than the outer diameter of the drive roller 202, firstly, the driven box 3 is disengaged from the end of the rotating rod 202. Then, the fixed roller 6 is fitted onto the outer wall of the drive roller 202. The semi-circular locking post 601 on the inner wall of the fixed roller 6 is then fitted into the groove 204 on the outer wall of the drive roller 202. The slot 602 on the inner wall of the fixed roller 6 is then engaged with the first limiting strip 203 on the outer wall of the drive roller 202. This allows the fixed roller 6 to rotate synchronously when the drive roller 202 rotates. Then, multiple sets of blades with large inner diameters are ground. The blade 3 is fitted onto the outer wall of the fixed roller 6, and the cut on the inner wall of the blade 3 is embedded in the second limiting strip 603 on the outer wall of the fixed roller 6. After the blade 3 is fully fitted onto the outer wall of the fixed roller 6, the equipment operator fixes the second fixing plate 401 onto the outer wall of the transmission roller 202 and the end of the fixed roller 6 with bolts, so that the second fixing plate 401 squeezes and fixes the multiple sets of blades 3 fitted onto the outer wall of the fixed roller 6. Finally, the stepper motor 505 drives the driven box 5 to move towards the transmission roller 202 in the opposite direction through the lead screw 504, so that the end of the rotating rod 2 is inserted into the driven box 2.
[0054] Although embodiments of the present invention have been shown and described, these specific embodiments are merely explanations of the present invention and are not intended to limit the invention. The specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. After reading this specification, those skilled in the art may make modifications, substitutions, and variations to the embodiments as needed without departing from the principles and spirit of the present invention, provided that such modifications, substitutions, and variations are within the scope of the claims of the present invention and are protected by patent law.
Claims
1. A grinding device for processing longitudinal shear blades, comprising a grinding machine (1), characterized in that: A rotating rod (2) is provided on one side of the grinding machine (1). A transmission roller (202) is fixed on the outer wall of the rotating rod (2). A first limiting strip (203) is fixedly installed on the outer wall of the transmission roller (202). Five sets of grooves (204) are opened on the outer wall of the transmission roller (202). A fixed roller (6) is movably installed on the outer wall of the transmission roller (202). Five sets of locking pins (601) are fixed on the inner wall of the fixed roller (6). A locking groove (602) is opened on the inner wall of the fixed roller (6). A second limiting strip (603) is fixed on the outer wall of the fixed roller (6). A blade (3) is sleeved on the outer wall of the fixed roller (6). A driven box (5) is provided at one end of the rotating rod (2).
2. The grinding device for processing longitudinal shear blades according to claim 1, characterized in that: A servo motor (104) is installed on the top of the grinding machine (1). A drive wheel (103) is fixed at one end of the servo motor (104). A toothed belt (102) is fitted on the outer wall of the drive wheel (103). A transmission wheel (101) is provided on the outer wall of the grinding machine (1). A speed reduction mechanism is provided inside the grinding machine (1). The two ends of the speed reduction mechanism inside the grinding machine (1) are connected to the rotating rod (2) and the transmission wheel (101) respectively.
3. The grinding device for processing longitudinal shear blades according to claim 1, characterized in that: One end of the transmission roller (202) is fixed with a retaining ring (206), and a first fixing plate (4) is installed on one side of the transmission roller (202). The outer diameter of the first limiting strip (203) and the transmission roller (202) matches the inner wall size of the blade (3) with a small inner hole diameter.
4. The grinding device for processing longitudinal shear blades according to claim 1, characterized in that: The locking post (601) is set to be semi-circular, and the groove (204) is shaped and sized to match the locking post (601).
5. The grinding device for processing longitudinal shear blades according to claim 3, characterized in that: The outer diameter of the second limiting strip (603) and the fixed roller (6) matches the inner wall size of the blade (3) with a large inner diameter. A second fixed plate (401) is installed at one end of the fixed roller (6), and the outer diameter of the second fixed plate (401) is larger than the outer diameter of the blade (3) with a large inner diameter.
6. The grinding device for processing longitudinal shear blades according to claim 5, characterized in that: Both the inner walls of the first fixed plate (4) and the second fixed plate (401) are provided with perforations (403).
7. The grinding device for processing longitudinal shear blades according to claim 6, characterized in that: Bolt holes (205) are provided on the outer wall of one end of the transmission roller (202) and the fixed roller (6), and multiple sets of mounting holes (402) are provided inside the first fixed plate (4) and the second fixed plate (401).
8. The grinding device for processing longitudinal shear blades according to claim 1, characterized in that: The driven box (5) has a drive block (502) and two sets of sliders (501) fixed at the bottom. The drive block (502) and sliders (501) are respectively installed with a lead screw (504) and a limit rod (503). A stepper motor (505) is installed at one end of the lead screw (504).
9. The grinding device for processing longitudinal shear blades according to claim 1, characterized in that: One end of the outer wall of the rotating rod (2) is fixed with a protrusion (201), and a support bearing assembly is installed on one side of the driven box (5), and the inner wall shape and size of the support bearing assembly match one end of the rotating rod (2).
10. The grinding device for processing longitudinal shear blades according to claim 6, characterized in that: A fixing post (207) is fixed to the outer wall of one end of the transmission roller (202), and insertion holes (404) are opened on the inner walls of the first fixing plate (4) and the second fixing plate (401).