A lens grinding machine for infrared lens production

Abstract

The present invention belongs to the field of lens processing technology, and discloses a lens grinding machine for infrared lens production, including a base, a support frame fixedly connected to the rear of the upper surface of the base, a drive motor fixedly connected to the upper surface of the support frame, a drive gear and an adjustment gear fixedly installed on the output shaft of the drive motor, an electromagnet fixedly connected to the left side of the support frame, and a bidirectional lead screw rotatably connected to the middle of the electromagnet. The present invention clamps the grinding lens at its central position through a clamping mechanism, and drives the driving motor to rotate and the bidirectional lead screw to rotate, so that the sliding plates on both sides move toward the middle, and the push ring pushes the driven gear 2 to move until the grinding head contacts the grinding lens, and then the telescopic rod is extended or shortened to drive the L-tooth plate and the rotating grinding head to move forward and backward, and the two cooperate with each other and the grinding head and the grinding lens are reversed, so that both sides of the lens are polished at the same time, which greatly improves the grinding and polishing efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of lens processing, in particular to a lens grinding machine for producing infrared lenses. Background Art

[0002] Lens grinding machines for infrared lens production are specialized equipment designed to process optical lenses used in the infrared spectrum. These lenses are usually made of materials with high transmittance to infrared light, such as germanium (Ge), silicon (Si), and zinc selenide (ZnSe). This type of equipment combines precision machinery, electronic control, and material processing technology to ensure that the processed lenses have extremely high optical performance and surface quality. Lens grinding machines for infrared lens production are also key technical equipment in the manufacture of infrared optical systems. Their accuracy and efficiency directly affect the performance and cost of the final product.

[0003] When grinding existing infrared lenses, the lens is usually fixed and supported at the bottom. After the grinding liquid is applied to the surface of the lens, the lens and the grinding head rotate in opposite directions to grind and polish one side of the lens. This grinding method is inefficient, and during the grinding and resurfacing process, the lens is easily scratched and damaged, resulting in the lens being scrapped, which greatly reduces the product yield. Summary of the invention

[0004] The object of the present invention is to provide a lens grinding machine for producing infrared lenses to solve the problems raised in the above-mentioned background technology.

[0005] In order to achieve the above-mentioned purpose, the present invention provides the following technical solutions: a lens grinding machine for infrared lens production, comprising a base, a support frame fixedly connected to the rear of the upper surface of the base, a drive motor fixedly connected to the upper surface of the support frame, a drive gear and an adjustment gear fixedly installed on the output shaft of the drive motor, an electromagnet fixedly connected to the left side of the support frame, a bidirectional lead screw rotatably connected to the middle part of the electromagnet, a permanent magnet fixedly installed in the middle part of the bidirectional lead screw, a driven gear 1 slidably connected to the bidirectional lead screw fixedly connected to the left side of the permanent magnet, and the bidirectional lead screw The two sides of the sliding plate are threadedly connected, and a telescopic rod is fixedly installed on the inner sides of the two sliding plates. The front end of the telescopic rod is fixedly connected to an L-tooth plate, and a rotating wheel is rotatably installed on the inner side of the L-tooth plate. A connecting ring is fixedly connected to the inner side of the rotating wheel, and a grinding head is fixedly connected to the inner side of the connecting ring. A sliding groove 1 is provided on the upper surface of the L-tooth plate, and a fixed block 1 fixedly connected to the sliding plate is slidably connected to the middle part of the sliding groove 1. A linkage gear is meshed under the L-tooth plate, and an adjusting mechanism is meshed on the rear side of the linkage gear. The front parts of the two sliding plates are slidably connected to sliding rods.

[0006] Preferably, it also includes two connecting blocks, an oil supply mechanism is fixedly installed on the front side of the connecting block, and the back side of the oil supply mechanism is connected to two liquid pipes, the upper surfaces of the two connecting blocks are fixedly connected to a clamping mechanism, the outer curved surface of the clamping mechanism is fixedly connected to a gear ring, the rear side of the gear ring is meshingly connected to a driven gear 2, the middle part of the driven gear 2 is fixedly connected to a transmission shaft, both ends of the transmission shaft are slidably connected to drive wheels, the outer side of the drive wheel is rotatably connected to a push ring fixedly connected to a sliding plate, and the curved surface of the drive wheel is sleeved with a synchronous belt.

[0007] Preferably, the adjustment mechanism includes a rack, a second slide groove is opened on the back of the rack, a fixed block second fixedly connected to the sliding plate is slidably connected in the middle of the second slide groove, a wheel frame is fixedly connected at the lower end of the rack, an adjusting wheel is rotatably installed in the middle of the wheel frame, and the adjusting wheel and the rotating wheel are both slidably connected to the synchronous belt.

[0008] Preferably, the clamping mechanism includes a ring body, both sides of the ring body are rotatably connected with half rings, the inner curved surface of the ring body is fixedly connected with a plurality of circumferentially arranged liquid jackets, the interior of the liquid jacket is slidably connected with a T-shaped shaft, the inner end of the T-shaped shaft is fixedly connected with a clamping pad, two annular cavities are provided on both sides of the ring body, the right annular cavity is connected with the outer liquid jacket of the T-shaped shaft, and the left annular cavity is connected with a connecting pipe, the inner end of the connecting pipe is connected with the inner liquid jacket of the T-shaped shaft, the annular cavities are connected with liquid pipes, and the half rings are fixedly connected to the connecting block.

[0009] Preferably, a transverse sliding groove and a longitudinal sliding groove are provided on the inner side of the sliding plate, the transverse sliding groove is slidingly connected to the L-tooth plate, the longitudinal sliding groove is slidingly connected to the wheel frame, and the sliding plate is rotationally connected to the linkage gear.

[0010] Preferably, the second driven gear is meshedly connected with the driving gear on the rear side, the transmission shaft and the connecting block are rotationally connected, and the sliding rod and the connecting block are fixedly connected.

[0011] Preferably, both ends of the sliding rod are fixedly connected to the base, both ends of the bidirectional screw rod are rotatably connected to the base, and the sliding plate is slidably connected to the base.

[0012] The beneficial effects of the present invention are as follows:

[0013] 1. The present invention clamps the grinding lens at its central position through a clamping mechanism, and drives the motor to rotate. The bidirectional screw rotates to move the sliding plates on both sides toward the middle, and the push ring pushes the driven gear 2 to move until the grinding head contacts the grinding lens. The telescopic rod is then extended or shortened to drive the L-tooth plate and the rotating grinding head to move forward and backward. The two cooperate with each other and the grinding head and the grinding lens reverse, so that both sides of the lens are polished at the same time, which greatly improves the grinding and polishing efficiency.

[0014] 2. The present invention supplies hydraulic oil to the right liquid pipe through the oil supply mechanism, and returns hydraulic oil to the left liquid pipe. The hydraulic oil entering the right annular cavity enters the interior of the outer liquid jacket of the T-shaped shaft through the connecting pipe, thereby pushing the T-shaped shaft to move toward the inner center, and pushing the hydraulic oil in the inner liquid jacket of the T-shaped shaft to enter the interior of the left annular cavity through the connecting pipe, and finally returns to the oil supply mechanism through the liquid pipe, and the T-shaped shaft moves toward the inner center until the lens to be ground is clamped in the center of the ring body, and then the grinding head is used to grind both sides of the lens at the same time, so as to avoid scratches and damage to the lens during the grinding and surface replacement process, which may lead to the problem of lens scrapping. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the structural appearance of the present invention;

[0016] Figure 2 It is a top view schematic diagram of the structure of the present invention;

[0017] Figure 3 It is a cross-sectional schematic diagram of the base structure of the present invention;

[0018] Figure 4 It is a schematic diagram of the clamping mechanism of the structure of the present invention;

[0019] Figure 5 It is a half-section schematic diagram of the clamping mechanism of the structure of the present invention.

[0020] In the figure: 1, base; 2, support frame; 3, drive motor; 4, drive gear; 5, adjustment gear; 6, electromagnet; 7, bidirectional screw rod; 8, permanent magnet; 9, driven gear 1; 10, sliding plate; 11, telescopic rod; 12, L-tooth plate; 13, rotating wheel; 14, connecting ring; 15, grinding head; 16, slide groove 1; 17, fixed block 1; 18, linkage gear; 19, adjustment mechanism; 191, rack; 192, slide groove 2; 19 3. Fixed block 2; 194. Wheel frame; 195. Adjusting wheel; 20. Sliding rod; 21. Connecting block; 22. Oil supply mechanism; 23. Liquid pipe; 24. Clamping mechanism; 241. Ring body; 242. Liquid jacket; 243. T-shaped shaft; 244. Clamping pad; 245. Annular cavity; 246. Connecting pipe; 247. Half ring; 25. Gear ring; 26. Driven gear 2; 27. Transmission shaft; 28. Driving wheel; 29. ​​Push ring; 30. Synchronous belt. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] like Figures 1 to 5 As shown, an embodiment of the present invention provides a lens grinding machine for infrared lens production, including a base 1, a support frame 2 is fixedly connected to the rear of the upper surface of the base 1, a driving motor 3 is fixedly connected to the upper surface of the support frame 2, a driving gear 4 and an adjusting gear 5 are fixedly installed on the output shaft of the driving motor 3, an electromagnet 6 is fixedly connected to the left side of the support frame 2, a bidirectional screw rod 7 is rotatably connected to the middle of the electromagnet 6, a permanent magnet 8 is fixedly installed in the middle of the bidirectional screw rod 7, a driven gear 9 slidably connected to the bidirectional screw rod 7 is fixedly connected to the left side of the permanent magnet 8, and sliding plates are threadedly connected to both sides of the bidirectional screw rod 7. 10, a telescopic rod 11 is fixedly installed on the inner side of the two sliding plates 10, and an L-toothed plate 12 is fixedly connected to the front end of the telescopic rod 11, a rotating wheel 13 is rotatably installed on the inner side of the L-toothed plate 12, a connecting ring 14 is fixedly connected to the inner side of the rotating wheel 13, and a grinding head 15 is fixedly connected to the inner side of the connecting ring 14. A sliding groove 16 is provided on the upper surface of the L-toothed plate 12, and a fixed block 17 fixedly connected to the sliding plate 10 is slidably connected to the middle part of the sliding groove 16, and a linkage gear 18 is meshed at the bottom of the L-toothed plate 12, and an adjustment mechanism 19 is meshed at the rear side of the linkage gear 18. The front sliding of the two sliding plates 10 The sliding plate 10 is connected to the connecting block 21, and the connecting block 21 also includes two connecting blocks 21. The front of the connecting block 21 is fixedly installed with an oil supply mechanism 22. The back of the oil supply mechanism 22 is connected with two liquid pipes 23. The upper surfaces of the two connecting blocks 21 are fixedly connected with a clamping mechanism 24. The outer curved surface of the clamping mechanism 24 is fixedly connected with a gear ring 25. The rear side of the gear ring 25 is meshedly connected with a driven gear 26. The middle part of the driven gear 26 is fixedly connected with a transmission shaft 27. Both ends of the transmission shaft 27 are slidably connected with a driving wheel 28. The outer side of the driving wheel 28 is rotatably connected with a push ring 29 fixedly connected to the sliding plate 10. The curved surface is sleeved with a synchronous belt 30, and its function is that the present invention clamps the grinding lens at its central position through the clamping mechanism 24, and drives it to rotate through the driving motor 3, and the bidirectional screw rod 7 rotates to make the sliding plates 10 on both sides move toward the middle, and the push ring 29 will push the driven gear 26 to move until the grinding head 15 contacts the grinding lens, and then the telescopic rod 11 is extended or shortened to drive the L-tooth plate 12 and the rotating grinding head 15 to move forward and backward. The two cooperate with each other and the grinding head 15 and the grinding lens are reversed, so that both sides of the lens are polished at the same time, which greatly improves the grinding and polishing efficiency.

[0023] The adjusting mechanism 19 comprises a rack 191, a second slide groove 192 is provided on the back of the rack 191, a second fixed block 193 fixedly connected to the sliding plate 10 is slidably connected in the middle of the second slide groove 192, a wheel frame 194 is fixedly connected to the lower end of the rack 191, an adjusting wheel 195 is rotatably installed in the middle of the wheel frame 194, the adjusting wheel 195 and the rotating wheel 13 are both slidably sleeved with the synchronous belt 30, a transverse slide groove and a longitudinal slide groove are provided on the inner side of the sliding plate 10, the transverse slide groove is slidably connected to the L tooth plate 12, the longitudinal slide groove is slidably connected to the wheel frame 194, the sliding plate 10 is rotatably connected to the linkage gear 18, and its function is that the telescopic rod 11 is extended or shortened to drive the L tooth plate 12 and the grinding head 15 to move forward and backward, the forward and backward movement of the L tooth plate 12 will drive the linkage gear 18 to rotate, and the rotation of the linkage gear 18 will drive the rack 191 to move up and down accordingly, so as to adjust the position of the adjusting wheel 195, so as to keep the synchronous belt 30 in a relatively tight state.

[0024] The clamping mechanism 24 includes a ring body 241, both sides of the ring body 241 are rotatably connected with a half ring 247, the inner curved surface of the ring body 241 is fixedly connected with a plurality of circumferentially arranged liquid jackets 242, the interior of the liquid jacket 242 is slidably connected with a T-shaped shaft 243, the inner end of the T-shaped shaft 243 is fixedly connected with a clamping pad 244, and two annular cavities 245 are provided on both sides of the ring body 241, the right annular cavity 245 is connected with the outer liquid jacket 242 of the T-shaped shaft 243, and the left annular cavity 245 is connected with a connecting pipe 246, the inner end of the connecting pipe 246 is connected with the inner liquid jacket 242 of the T-shaped shaft 243, and the annular cavities 245 are connected with the liquid pipe 23 The half ring 247 is fixedly connected to the connecting block 21, and its function is to supply hydraulic oil to the right liquid pipe 23 through the oil supply mechanism 22, and return hydraulic oil to the left liquid pipe 23. The hydraulic oil entering the right annular cavity 245 enters the inside of the outer liquid jacket 242 of the T-shaped shaft 243 through the connecting pipe 246, thereby pushing the T-shaped shaft 243 to move toward the inner center, and pushing the hydraulic oil in the inner liquid jacket 242 of the T-shaped shaft 243 to enter the inside of the left annular cavity 245 through the connecting pipe 246, and finally returns to the oil supply mechanism 22 through the liquid pipe 23, and the T-shaped shaft 243 moves toward the inner center until the lens to be ground is clamped in the middle of the ring body 241.

[0025] Among them, the driven gear 26 is meshed and connected with the driving gear 4 on the rear side, the transmission shaft 27 and the connecting block 21 are rotationally connected, the sliding rod 20 and the connecting block 21 are fixedly connected, the two ends of the sliding rod 20 are fixedly connected to the base 1, the two ends of the bidirectional lead screw 7 are rotationally connected to the base 1, and the sliding plate 10 is slidingly connected to the base 1. Its function is that the electromagnet 6 is energized in the forward direction to generate a magnetic field that attracts the permanent magnet 8, driving the permanent magnet 8 and the driven gear 1 9 to move to the right, and the driven gear 1 9 will mesh with the adjusting gear 5, and the driving motor 3 will work to drive the driving gear 4 and the adjusting gear 5 to rotate, and the adjusting gear 5 will drive the bidirectional lead screw 7 to rotate, so that the sliding plates 10 on both sides move toward the middle; the electromagnet 6 is energized in the reverse direction to generate a magnetic field that repels the permanent magnet 8, driving the permanent magnet 8 and the driven gear 1 9 to move to the left, and the driven gear 1 9 is disengaged from the adjusting gear 5.

[0026] Working principle:

[0027] Before the present invention is used, the sliding plate 10 is located at both ends of the bidirectional screw 7, the grinding head 15 is in a position colinear with the central axis of the gear ring 25, the adjusting gear 5 and the driven gear 9 are in a non-meshing state, and the annular cavity 245, the connecting pipe 246, and both sides of the T-shaped shaft 243 are filled with hydraulic oil;

[0028] When the present invention is used, the surface of the lens to be ground is coated with grinding liquid, and hydraulic oil is supplied to the right liquid pipe 23 through the oil supply mechanism 22, and the left liquid pipe 23 returns the hydraulic oil. The hydraulic oil entering the right annular cavity 245 enters the inside of the outer liquid jacket 242 of the T-shaped shaft 243 through the connecting pipe 246, thereby pushing the T-shaped shaft 243 to move toward the inner center, and pushing the hydraulic oil in the inner liquid jacket 242 of the T-shaped shaft 243 to enter the inside of the left annular cavity 245 through the connecting pipe 246, and finally returns to the oil supply mechanism 22 through the liquid pipe 23, and the T-shaped shaft 243 moves toward the inner center until the lens to be ground is clamped in the middle of the ring body 241, and the oil supply mechanism 22 stops working to maintain the oil pressure;

[0029] After the grinding lens is clamped, the electromagnet 6 is energized in the forward direction to generate a magnetic field that attracts the permanent magnet 8, driving the permanent magnet 8 and the driven gear 1 9 to move to the right, and the driven gear 1 9 will mesh with the adjusting gear 5, and the drive motor 3 will work to drive the driving gear 4 and the adjusting gear 5 to rotate. The adjusting gear 5 will drive the bidirectional screw 7 to rotate, so that the sliding plates 10 on both sides move toward the middle, and the push ring 29 will push the driven gear 2 26 to move until the grinding head 15 contacts the grinding lens, and the electromagnet 6 is energized in the reverse direction to generate a magnetic field that repels the permanent magnet 8, driving the permanent magnet 8 and the driven gear 1 9 to the left. The driven gear 1 9 is disengaged from the adjusting gear 5, and the rotating driving gear 4 drives the driven gear 2 26 to rotate. The driven gear 2 26 drives the gear ring 25, the ring body 241 and the grinding lens to rotate. The driven gear 2 26 drives the transmission shaft 27 and the driving wheels 28 at both ends to rotate. The driving wheel 28 drives the adjusting wheel 195 and the rotating wheel 13 to rotate through the synchronous belt 30, thereby causing the grinding head 15 to rotate in the opposite direction to the grinding lens. When the grinding head 15 contacts the grinding lens, it grinds and polishes the grinding lens.

[0030] During the grinding and polishing of the grinding lens, the telescopic rod 11 is extended or shortened to drive the L-toothed plate 12 and the grinding head 15 to move forward and backward. The forward and backward movement of the L-toothed plate 12 drives the linkage gear 18 to rotate. The rotation of the linkage gear 18 drives the rack 191 to move up and down accordingly, thereby adjusting the position of the adjusting wheel 195, so as to keep the synchronous belt 30 in a relatively tight state. Then, the sliding plate 10 is moved left and right, so that the grinding head 15 can grind and polish the edge of the grinding lens.

[0031] After polishing is completed, the driven gear 9 meshes with the adjusting gear 5, and the bidirectional screw 7 rotates in the opposite direction, thereby driving the sliding plate 10 to move on both sides, and the hydraulic oil is supplied to the liquid pipe 23 on the left through the oil supply mechanism 22, and the hydraulic oil is returned to the liquid pipe 23 on the right, so that the contact pair of grinding lenses is clamped, the telescopic rod is extended or shortened, and the grinding head 15 is driven to reset to the center position.

[0032] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0033] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A lens grinding machine for producing infrared lenses, comprising a base (1), a support frame (2) being fixedly connected to the rear of the upper surface of the base (1), and a drive motor (3) being fixedly connected to the upper surface of the support frame (2), characterized in that: A driving gear (4) and an adjusting gear (5) are fixedly mounted on the output shaft of the driving motor (3); an electromagnet (6) is fixedly connected to the left side of the supporting frame (2); a bidirectional screw rod (7) is rotatably connected to the middle of the electromagnet (6); a permanent magnet (8) is fixedly mounted to the middle of the bidirectional screw rod (7); a driven gear (9) slidably connected to the bidirectional screw rod (7) is fixedly connected to the left side of the permanent magnet (8); sliding plates (10) are threadedly connected to both sides of the bidirectional screw rod (7); telescopic rods (11) are fixedly mounted on the inner sides of the two sliding plates (10); and an L-tooth plate (11) is fixedly connected to the front end of the telescopic rod (11). 12), a rotating wheel (13) is rotatably mounted on the inner side of the L-tooth plate (12), a connecting ring (14) is fixedly connected to the inner side of the rotating wheel (13), a grinding head (15) is fixedly connected to the inner side of the connecting ring (14), a sliding groove (16) is provided on the upper surface of the L-tooth plate (12), a fixed block (17) fixedly connected to the sliding plate (10) is slidably connected in the middle of the sliding groove (16), a linkage gear (18) is meshed at the bottom of the L-tooth plate (12), an adjusting mechanism (19) is meshed at the rear side of the linkage gear (18), and a sliding rod (20) is slidably connected to the front of the two sliding plates (10); It also comprises two connecting blocks (21), the front of the connecting blocks (21) being fixedly mounted with an oil supply mechanism (22), the back of the oil supply mechanism (22) being connected with two liquid pipes (23), the upper surfaces of the two connecting blocks (21) being fixedly connected with a clamping mechanism (24), the outer curved surface of the clamping mechanism (24) being fixedly connected with a gear ring (25), the rear side of the gear ring (25) being meshingly connected with a driven gear 2 (26), the middle part of the driven gear 2 (26) being fixedly connected with a transmission shaft (27), both ends of the transmission shaft (27) being slidably connected with a driving wheel (28), the outer side of the driving wheel (28) being rotatably connected with a push ring (29) fixedly connected with the sliding plate (10), and the curved surface of the driving wheel (28) being sleeved with a synchronous belt (30); The adjusting mechanism (19) comprises a rack (191), a second slide groove (192) is provided on the back of the rack (191), a second fixed block (193) fixedly connected to the sliding plate (10) is slidably connected in the middle of the second slide groove (192), a wheel frame (194) is fixedly connected at the lower end of the rack (191), an adjusting wheel (195) is rotatably mounted in the middle of the wheel frame (194), and the adjusting wheel (195) and the rotating wheel (13) are both slidably sleeved with the synchronous belt (30).

2. The lens grinding machine for producing infrared lenses according to claim 1, characterized in that: The clamping mechanism (24) comprises a ring body (241), both sides of the ring body (241) are rotatably connected with half rings (247), the inner curved surface of the ring body (241) is fixedly connected with a plurality of circumferentially arranged liquid sleeves (242), the interior of the liquid sleeve (242) is slidably connected with a T-shaped shaft (243), the inner end of the T-shaped shaft (243) is fixedly connected with a clamping pad (244), and both sides of the ring body (241) are provided with Two annular cavities (245), the right annular cavity (245) is in communication with the outer liquid jacket (242) of the T-shaped shaft (243), and the left annular cavity (245) is in communication with a connecting pipe (246), the inner end of the connecting pipe (246) is in communication with the inner liquid jacket (242) of the T-shaped shaft (243), the annular cavities (245) are in communication with the liquid pipe (23), and the half ring (247) is fixedly connected to the connecting block (21).

3. The lens grinding machine for producing infrared lenses according to claim 2, characterized in that: A transverse sliding groove and a longitudinal sliding groove are provided on the inner side of the sliding plate (10); the transverse sliding groove is slidingly connected to the L-tooth plate (12); the longitudinal sliding groove is slidingly connected to the wheel frame (194); and the sliding plate (10) is rotationally connected to the linkage gear (18).

4. The lens grinding machine for producing infrared lenses according to claim 3, characterized in that: The second driven gear (26) is meshedly connected with the rear driving gear (4), the transmission shaft (27) and the connecting block (21) are rotationally connected, and the sliding rod (20) and the connecting block (21) are fixedly connected.

5. The lens grinding machine for producing infrared lenses according to claim 4, characterized in that: The two ends of the sliding rod (20) are fixedly connected to the base (1), the two ends of the bidirectional screw rod (7) are rotatably connected to the base (1), and the sliding plate (10) is slidably connected to the base (1).

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