Steel bowl channel grinding device

Abstract

The invention provides a steel bowl channel grinding device, and belongs to the technical field of bearing machining, the steel bowl channel grinding device comprises a machine tool and a machining table located in the machine tool, the machining table is provided with a placing plate, the steel bowl channel grinding device further comprises a clamping mechanism, the clamping mechanism comprises a clamping jaw, when the clamping jaw is opened, the clamping jaw is used for clamping and fixing a ferrule and can drive the ferrule to rotate, and the clamping jaw is used for clamping and fixing the ferrule; when the clamping jaws are closed, the ferrule can be detached; the cleaning mechanism comprises a fixed ring mounted on the movable plate; before the bearing ring is machined, impurity particles on the surface of the contact position of the clamping jaw and the ring are cleaned up, and on the premise that it is guaranteed that the clamping jaw can provide enough support to prevent the ring from deforming, it is avoided that due to the influence of the impurity particles, clamping is unstable, ring deformation and uneven grinding are caused, or scratches and indentations appear on the surface of the ring, and the machining quality of the bearing ring is improved. The service life of the clamping jaw is prolonged, and surface abrasion is prevented from being aggravated.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of bearing processing, and particularly relates to a steel bowl groove grinding device. BACKGROUND

[0002] The steel bowl groove grinding is a process of machining a high-precision groove on a bearing ring (steel bowl) through a grinding process. The core principle is to remove material and form a groove profile (such as a circular arc, an angle, etc.) meeting design requirements by using the relative motion of a high-speed rotating grinding wheel and a workpiece, so as to achieve the design requirements of size, shape and surface quality.

[0003] A bearing groove grinding device is disclosed in Chinese Patent No. CN116900871B, which comprises a base, a driving member installed on the upper end face of the base near one side edge, a fixed seat installed on the upper end face of the base near the other side edge, two supporting shafts symmetrically and rotatably installed on the side face of the fixed seat, a bearing shaft fixedly installed on the upper end face of the fixed seat, the bearing shaft being located on the positive side of the driving member, a pushing frame rotatably installed on one end of the bearing shaft, a reciprocating pushing member installed on the other end of the bearing shaft, the end of the reciprocating pushing member being rotatably connected with the upper end of the pushing frame, and a grinding member installed on the side face of the pushing frame. The grinding device shortens the grinding time, improves the grinding efficiency, and also improves the grinding quality.

[0004] However, the above technical solution still has the following problems. When the bearing ring is clamped and fixed, the clamping member needs to increase the contact surface with the bearing ring to reduce the deformation of the ring when it is fixed. However, if the contact position of the clamping member and the ring is not thoroughly cleaned in advance, impurity particles may remain, which may scratch the positioning end face of the workpiece or cause the clamping positioning surface to wear out, and the impurities may reduce the actual contact area between the workpiece and the clamp, causing the workpiece to deviate during processing. SUMMARY

[0005] The purpose of the present application is to provide a steel bowl groove grinding device, which aims to solve the problem of impurity particles remaining at the contact position of the clamping member and the ring in the prior art, affecting the processing quality of the bearing ring.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical solution: a steel bowl groove grinding device, comprising a machine tool and a processing table located inside the machine tool, the processing table being provided with a placing plate, and further comprising: A clamping mechanism is slidably installed on the processing table, and the clamping mechanism comprises a jaw, which is used to clamp and fix the ring and can drive the ring to rotate when the jaw is opened, and can disassemble the ring when the jaw is closed. The cleaning mechanism is installed on the clamping mechanism, and the cleaning mechanism comprises a fixed ring installed on the moving plate, a cleaning ring rotatably connected to the inner side of the fixed ring, a plurality of groups of extension plates provided on the cleaning ring, air outlets and brushes provided on the extension plates, when the clamping jaws are closed, the clamping jaws are located on the side of the extension plates close to the axis and are in contact with the brushes, the air outlets can blow air to the direction of the clamping jaws, and the cleaning ring is provided with a clutch mechanism, when the clamping jaws rotate, the clutch mechanism is used to make the clamping jaws relatively rotate with the extension plates. The arc-shaped supporting blocks are arranged on the placing plate and are used for pre-fixing the sleeve ring, the inner wall of the sleeve ring is in contact with the brushes, the air outlets can blow air to the direction of the inner wall of the sleeve ring, when the clamping jaws are unfolded and a gap is left between the clamping jaws and the sleeve ring, the cleaning ring can be made to rotate with the clamping jaws and the extension plates can be made to relatively rotate with the sleeve ring through the clutch mechanism.

[0007] Further technical solutions of the present application are that the polishing mechanism is slidably installed on the machining table, the polishing mechanism comprises a polishing frame slidably installed on the machining table, a supporting frame is rotatably installed on the polishing frame, a guide groove is arranged on the side of the supporting frame close to the placing plate along the moving direction of the polishing frame, the side of the guide groove close to the placing plate is inclined to the rotation center of the supporting frame, and the side of the clamping jaw close to the end of the guide groove is provided with a guide column capable of sliding along the guide groove.

[0008] Further technical solutions of the present application are that the supporting frame is provided with a spraying ring installed on the polishing frame on the outer side, and the spraying ring is provided with a spraying head on the side close to the placing plate.

[0009] Further technical solutions of the present application are that the machine tool is provided with a second driving device for driving the polishing frame to slide, a grinding wheel is installed on the side of the polishing frame close to the placing plate, and a second motor is installed on the polishing frame for driving the grinding wheel to rotate around the axis.

[0010] Further technical solutions of the present application are that the clamping mechanism further comprises a moving plate slidably installed on the machining table, a hydraulic chuck is rotatably installed on the moving plate, the clamping jaws are slidably installed on the hydraulic chuck, a first driving device is arranged in the machine tool for driving the moving plate to slide, a first motor is installed on the moving plate for driving the hydraulic chuck to rotate around the axis, and the side surfaces of the clamping jaws away from each other are provided as arc surfaces.

[0011] Further technical solutions of the present application are that the fixed ring is provided with an air inlet, the fixed ring and the cleaning ring are provided with a communication cavity in communication, the communication cavity is in communication with the air inlet and the air outlet, the air outlet on one of the extension plates is arranged on the side away from the axis of the cleaning ring, the brushes are arranged on the side close to the axis of the cleaning ring, and the positions of the air outlets and the brushes on the adjacent two extension plates are transposed.

[0012] Further technical solutions of the present application are that the clutch mechanism comprises a first limiting groove and a first limiting block, the first limiting groove is arranged on the inner side of the cleaning ring and is located between the two adjacent extension plates, the first limiting block is matched with the first limiting groove and is arranged on the arc surface of the claw, the slide rod is installed through the fixing ring, the slide rod can reciprocate along the axis direction of the fixing ring, the spring is connected to the side of the slide rod close to the placing plate, the other end of the spring is connected with the fixing ring, the second limiting block is arranged on the side of the slide rod away from the spring, and the second limiting groove matched with the second limiting block is arranged on the cleaning ring.

[0013] Further technical solutions of the present application are that the arc-shaped supporting block has magnetism, and the through hole penetrating through the placing plate is arranged above the arc-shaped supporting block.

[0014] Compared with the prior art, the present application has the following beneficial effects: 1. The brush on the extension plate cooperates with the air outlet to clean the surface impurity particles at the contact position of the claw and the sleeve before machining the bearing sleeve, so that the claw can provide sufficient support to prevent the sleeve from deforming, the influence of the impurity particles is prevented, the sleeve is prevented from deforming and uneven polishing, or the surface of the sleeve is prevented from being scratched and indented, the service life of the claw is prolonged, and the surface wear of the claw is prevented from being aggravated.

[0015] 2. The supporting frame assists in supporting the claw, prevents the sleeve from shaking under stress during machining, prevents the accuracy error caused by inaccurate claw shaft positioning, and prevents the machining from being unstable due to the gap generated by the wear of the claw or the decrease in rigidity caused by fatigue after long-term use of the clamp. DETAILED DESCRIPTION

[0016] The accompanying drawings are used to provide a further understanding of the present application, and constitute a part of the specification, together with the embodiments of the present application, to explain the present application, and do not constitute a limitation on the present application. In the drawings: Figure 1 It is a schematic view of the overall structure of the specific embodiment in the present application; Figure 2 It is a schematic view of the structure of the specific embodiment in the present application; Figure 3 It is an axonometric sectional view of the specific embodiment in the present application; Figure 4 It is Figure 3 It is an enlarged schematic view of the structure at A in the present application; Figure 5 It is a schematic view of the structure of the clamping mechanism in the specific embodiment in the present application; Figure 6 It is a schematic view of the structure of the claw and the cleaning ring in the specific embodiment in the present application; Figure 7The mounting structure diagram of the pawl and the cleaning ring in the specific embodiment of the present application; Figure 8 The structure diagram of the cleaning mechanism in the specific embodiment of the present application; Figure 9 The cooperation structure diagram of the clamping mechanism and the cleaning mechanism in the specific embodiment of the present application; Figure 10 The structure diagram of the pawl and the polishing frame in the specific embodiment of the present application.

[0017] In the figure: 1, machine tool; 2, machining table; 21, placing plate; 22, arc-shaped supporting block; 23, through hole; 3, clamping mechanism; 31, moving plate; 32, hydraulic chuck; 33, first motor; 34, pawl; 341, first limiting block; 342, guide column; 4, cleaning mechanism; 41, fixed ring; 411, air inlet; 42, cleaning ring; 421, extension plate; 422, air outlet; 423, brush; 424, second limiting groove; 43, first limiting groove; 44, sliding rod; 441, spring; 442, second limiting block; 5, polishing mechanism; 51, polishing frame; 52, grinding wheel; 53, second motor; 54, supporting frame; 541, guide groove; 55, spraying ring; 551, spraying head. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0019] Please refer to Figures 1-10 The present application provides the following technical solutions: a steel bowl groove polishing device, comprising a machine tool 1, a machining table 2, a clamping mechanism 3, a cleaning mechanism 4 and a polishing mechanism 5. The machine tool 1 is horizontally placed on the ground, the machining table 2 is arranged inside the machine tool 1, the clamping mechanism 3 is installed on the upper surface of the machining table 2 and can reciprocally move along the machining table 2, the clamping mechanism 3 can fix the sleeve ring, the cleaning mechanism 4 is installed on the clamping mechanism 3, the cleaning mechanism 4 can clean the contact position between the clamping mechanism 3 and the sleeve ring, the polishing mechanism 5 is installed on the machining table 2 and can reciprocally move along the machining table 2, the clamping mechanism 3 and the polishing mechanism 5 can approach or move away from each other when sliding along the machining table 2, during work, the clamping mechanism 3 and the sleeve ring are first cleaned by the cleaning mechanism 4 to remove the adhered impurity particles, then the sleeve ring is fixed by the clamping mechanism 3, and then the polishing mechanism 5 approaches the sleeve ring and polishes the groove of the sleeve ring.

[0020] Please refer toFigures 2-4 A placement plate 21 is provided on the upper surface of the processing table 2, and an arc-shaped support block 22 is provided on the side of the placement plate 21 close to the grinding mechanism 5. The arc-shaped support block 22 cooperates with the ring and supports it, and the arc-shaped support block 22 is magnetic, which can prevent the ring placed on it from falling. A through hole 23 is provided above the arc-shaped support block 22, which passes through the placement plate 21, and the axis of the through hole 23 coincides with the axis of the ring placed on the arc-shaped support block 22. The clamping mechanism 3 is installed on the side of the placement plate 21 away from the ring, and a guide rail is provided on the upper surface of the processing table 2, so that the clamping mechanism 3 can clamp the ring along the processing table 2 close to the placement plate 21 and through the through hole 23.

[0021] See also Figures 2-5 The first motor 33 is connected to the hydraulic chuck 32, and the output end of the first motor 33 is connected to the hydraulic chuck 32. The hydraulic chuck 32 is driven by the first motor 33 to rotate along the movable plate 31 along the fixed axis, and the rotation axis of the hydraulic chuck 32 coincides with the axis of the through hole 23. A plurality of groups of clamping jaws 34 are slidably mounted on the hydraulic chuck 32. In this embodiment, four groups of clamping jaws 34 are provided. The hydraulic chuck 32 can be driven to move closer to or away from each other on the hydraulic chuck 32 by the hydraulic chuck 32. The side surfaces of the side where the clamping jaws 34 are away from each other are set as arc surfaces, so that they can fully fit with the inner ring of the ring when clamping.

[0022] After the ring is placed on the arc-shaped support block 22, the first driving device drives the movable plate 31 to move and approach the placement plate 21. At this time, the claws 34 move to the inner side of the ring through the through hole 23, and the hydraulic chuck 32 drives the claws 34 to move away from each other and approach the inner ring of the ring to clamp and fix it, or approach each other and move toward the axial direction of the through hole 23.

[0023] See also Figure 4 、 Figures 6-9The cleaning mechanism 4 comprises a fixed ring 41 mounted on the moving plate 31 through a connecting rod, a cleaning ring 42 rotatably connected to the inner side of the fixed ring 41, an annular cavity provided in the inner side of the fixed ring 41 and the cleaning ring 42, the openings of the two cavities being capable of cooperating to form a communication cavity, and the cooperation part being capable of relative rotation, so that the communication cavity is sealed when the cleaning ring 42 rotates along the fixed ring 41, an air inlet 411 provided on the fixed ring 41, gas being capable of entering the communication cavity through the air inlet 411, a plurality of extension plates 421 provided on the cleaning ring 42, four extension plates 421 being uniformly provided in the embodiment, an air outlet 422 and a brush 423 provided on the two sides of the extension plate 421, the air outlet 422 being in communication with the communication cavity, and the gas in the communication cavity being capable of being blown out from the air outlet 422, the air outlet 422 on one of the extension plates 421 being provided on the side away from the axis of the cleaning ring 42, the brush 423 being provided on the side close to the axis of the cleaning ring 42, and the positions of the air outlet 422 and the brush 423 on the adjacent two extension plates 421 being inversed. When the moving plate 31 approaches the placing plate 21, the extension plates 421 can be moved to the inner side of the sleeve ring, and the brushes 423 on two of the extension plates 421 are in contact with the inner ring of the sleeve ring, and the air outlets 422 on the other two extension plates 421 blow air towards the inner ring of the sleeve ring; when the claws 34 approach each other to the closest position, the brushes 423 on the two extension plates 421 are in contact with the arc surface on the claws 34, and the air outlets 422 on the other two extension plates 421 blow air towards the arc surface on the claws 34.

[0024] The clutch mechanism comprises a first limiting groove 43 provided in the inner side of the cleaning ring 42, a plurality of first limiting grooves 43 are provided, and the first limiting grooves 43 are provided between the adjacent two extension plates 421, and a first limiting block 341 provided on the arc surface of the claw 34 and matched with the first limiting groove 43. When the claws 34 move away from each other, the first limiting block 341 can slide into the first limiting groove 43, and when the claws 34 approach each other, the first limiting block 341 slides out of the first limiting groove 43 until completely separated. A sliding rod 44 is installed through the fixed ring 41, the sliding rod 44 can reciprocate along the axis direction of the fixed ring 41, a spring 441 is connected to the side of the sliding rod 44 close to the placing plate 21, the other end of the spring 441 is connected to the fixed ring 41, a second limiting block 442 is provided on the side of the sliding rod 44 away from the spring 441, a second limiting groove 424 matched with the second limiting block 442 is provided on the cleaning ring 42, and the second limiting block 442 is inserted into the second limiting groove 424 and limits the cleaning ring 42 in the initial state through the spring 441, when the moving plate 31 moves towards the placing plate 21, the sliding rod 44 approaches the placing plate 21 and presses the spring 441 after contacting the placing plate 21, the fixed ring 41 continues to approach the placing plate 21, and the second limiting block 442 slides along the inner side of the second limiting groove 424 until completely separated.

[0025] When working, first drive the jaws 34 to approach each other to the nearest position by the hydraulic chuck 32, drive the hydraulic chuck 32 to rotate by the first motor 33, at this time the brush 423 on the extension plate 421 contacts the arc surface of the jaws 34 and sweeps the surface, at the same time cooperate with the air outlet 422 to constantly blow air to remove the impurity particles on the arc surface of the jaws 34; then drive the moving plate 31 to move to the direction of approaching the placing plate 21 by the first driving device, when the jaws 34 move to the inside of the collar, the slide rod 44 contacts the placing plate 21 and makes the second limiting block 442 slide along the inside of the second limiting groove 424 to completely separate, at this time the hydraulic chuck 32 drives the jaws 34 to move away from each other for a distance, so that the first limiting block 341 slides into the first limiting groove 43, then the hydraulic chuck 32 rotates and drives the cleaning ring 42 to rotate synchronously by the first limiting block 341, at this time the brush 423 on the extension plate 421 contacts the inner ring of the collar and sweeps the surface, at the same time cooperate with the air outlet 422 to constantly blow air to remove the impurity particles on the inner ring of the collar, the arc-shaped supporting block 22 adsorbs the collar to prevent the collar from moving when sweeping and blowing air. After sweeping, the jaws 34 continue to move away until the arc surface contacts and clamps the inner ring of the collar, then the moving plate 31 continues to move for a distance, so that the collar separates from the arc-shaped supporting block 22 to avoid the interference of the arc-shaped supporting block 22 to the polishing of the collar.

[0026] Please refer to Figure 2 、 Figure 3 and Figure 10 , the polishing mechanism 5 includes a polishing frame 51, the polishing frame 51 slides along the guide rail on the machining table 2 to approach or move away from the placing plate 21, the machine tool 1 is provided with a second driving device (not shown in the figure) for driving the polishing frame 51 to slide, the polishing frame 51 is installed with a grinding wheel 52 on the side close to the placing plate 21, the grinding wheel 52 is moved to the side of the collar and polishes the channel of the outer ring of the collar, the polishing frame 51 is installed with a second motor 53, the output end of the second motor 53 is connected with the grinding wheel 52, the grinding wheel 52 is driven to rotate by the second motor 53 and processes the collar. The supporting frame 54 is rotatably installed on the polishing frame 51, the rotation axis of the supporting frame 54 is coaxial with the hydraulic chuck 32, the supporting frame 54 is provided with a guide groove 541 on the side close to the placing plate 21 along the moving direction of the polishing frame 51, the side close to the placing plate 21 of the guide groove 541 is inclined to the rotation center of the supporting frame 54, the side end of the jaws 34 close to the guide groove 541 is provided with a guide column 342 which can slide along the guide groove 541.

[0027] When the collet is clamped by the claw 34, the polishing frame 51 is close to the placement plate 21, at this time the guide groove 541 far away from the side of the placement plate 21 can just contact with the guide column 342 and assist the support of the guide column 342, realize the fixation of both sides of the collet at the same time, prevent the collet from shaking during the rotation processing, and avoid the problem that the collet is clamped unstably due to the serious wear of the claw 34 after long time use. The hydraulic chuck 32 drives the claw 34 to stop at the same fixed position after each rotation, which ensures that the relative position of the components of the device remains unchanged after stopping, and prevents the relative position of some structures from changing to cause the failure of cooperation during the next work.

[0028] The support frame 54 is provided with a spraying ring 55 installed on the polishing frame 51, and the spraying ring 55 is provided with a spraying head 551 close to the side of the placement plate 21. When the polishing frame 51 is close to the placement plate 21 for processing, the spraying ring 55 works synchronously and sprays the cooling liquid from the spraying head 551 to cool the processing part of the collet, which avoids the high temperature of the processing position of the collet caused by the spraying only on the polishing position. Moreover, the spraying head 551 can flush and remove the impurity particles adhered on the processing position of the collet and the brush 423, which avoids the influence of too many impurity particles on the precision during polishing and the subsequent cleaning work of the brush 423.

Claims

1. A steel bowl groove machining apparatus comprising: Machine tool (1) and machining table (2) located inside the machine tool (1), the machining table (2) is provided with a placement plate (21), characterized by further comprising: Clamping mechanism (3) is slidingly installed on the machining table (2), the clamping mechanism (3) comprises a jaw (34), when the jaw (34) is opened, it is used for clamping and fixing the sleeve ring and can drive the sleeve ring to rotate, when the jaw (34) is closed, the sleeve ring can be disassembled; Cleaning mechanism (4) is installed on the clamping mechanism (3), the cleaning mechanism (4) comprises a fixed ring (41) installed on the moving plate (31), the inner side of the fixed ring (41) is rotatably connected with a cleaning ring (42), a plurality of extension plates (421) are arranged on the cleaning ring (42), the extension plates (421) are provided with air outlets (422) and brushes (423), when the jaw (34) is closed, the jaw (34) is located on the side of the extension plate (421) close to the axis and is in contact with the brush (423), the air outlet (422) can blow air to the direction of the jaw (34), the cleaning ring (42) is provided with a clutch mechanism, when the jaw (34) rotates, the jaw (34) is relatively rotated with the extension plate (421) through the clutch mechanism; The placement plate (21) is provided with an arc-shaped supporting block (22) for pre-fixing the sleeve ring, the inner wall of the sleeve ring is in contact with the brush (423), and the air outlet (422) can blow air to the inner wall of the sleeve ring, when the jaw (34) is unfolded and a gap is left between the jaw (34) and the sleeve ring, the cleaning ring (42) can be rotated with the jaw (34) through the clutch mechanism, and the extension plate (421) is relatively rotated with the sleeve ring.

2. A steel bowl groove channeling device as defined in claim 1, wherein: The machining table (2) is provided with a polishing mechanism (5) slidingly installed thereon, the polishing mechanism (5) comprises a polishing frame (51) slidingly installed on the machining table (2), a supporting frame (54) is rotatably installed on the polishing frame (51), the supporting frame (54) is provided with a guide groove (541) on the side close to the placement plate (21) along the moving direction of the polishing frame (51), the side close to the placement plate (21) of the guide groove (541) is inclined to the rotation center of the supporting frame (54), and the side end of the jaw (34) close to the guide groove (541) is provided with a guide column (342) capable of sliding along the guide groove (541).

3. A steel bowl groove channeling device as defined in claim 2, wherein: The outer side of the supporting frame (54) is provided with a spraying ring (55) installed on the polishing frame (51), and the spraying ring (55) is provided with a spraying head (551) on the side close to the placement plate (21).

4. A steel bowl groove channeling device as defined in claim 3, wherein: The machine tool (1) is provided with a second driving device for driving the polishing frame (51) to slide, the polishing frame (51) is provided with a grinding wheel (52) on the side close to the placement plate (21), and the polishing frame (51) is provided with a second motor (53) for driving the grinding wheel (52) to rotate around the axis.

5. A steel bowl groove channeling device as defined in claim 1, wherein: The clamping mechanism (3) further comprises a moving plate (31) slidingly installed on the machining table (2), a hydraulic chuck (32) is rotatably installed on the moving plate (31), a claw (34) is slidingly installed on the hydraulic chuck (32), a first driving device for driving the moving plate (31) to slide is arranged in the machine tool (1), a first motor (33) for driving the hydraulic chuck (32) to rotate around a fixed axis is installed on the moving plate (31), and the side surfaces of the claws (34) away from each other are provided in an arc shape.

6. A steel bowl groove channeling device as defined in claim 5 wherein: The fixed ring (41) is provided with an air inlet (411), the fixed ring (41) and the cleaning ring (42) are provided with a communication cavity in communication, and the communication cavity is in communication with the air inlet (411) and the air outlet (422). The air outlet (422) on one of the extension plates (421) is arranged on the side away from the axis of the cleaning ring (42), the brush (423) is arranged on the side close to the axis of the cleaning ring (42), and the positions of the air outlets (422) and the brushes (423) on the adjacent two extension plates (421) are transposed.

7. A steel bowl groove channeling device as defined in claim 1 wherein: The clutch mechanism comprises a first limiting groove (43) and a first limiting block (341), the first limiting groove (43) is arranged on the inner side of the cleaning ring (42) and located between the adjacent two extension plates (421), the first limiting block (341) is arranged on the arc surface of the claw (34) and matched with the first limiting groove (43), the slide rod (44) is installed through the fixed ring (41) and can slide reciprocally along the axis direction of the fixed ring (41), the spring (441) is connected to the side of the slide rod (44) close to the placement plate (21), the other end of the spring (441) is connected to the fixed ring (41), the second limiting block (442) is arranged on the side of the slide rod (44) away from the spring (441), and the second limiting groove (424) matched with the second limiting block (442) is arranged on the cleaning ring (42).

8. A steel bowl groove way device as defined in claim 1, wherein: The arc-shaped support block (22) has magnetism, and the arc-shaped support block (22) is provided with a through hole (23) penetrating the placement plate (21).

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