Wax oil coating device for surface treatment of solid wood furniture panels

Abstract

The present invention discloses a wax oil coating device for surface treatment of solid wood furniture panels in the field of panel spraying technology, comprising a loading device, a spraying device and a unloading device, and also comprising a plurality of clamping frames for clamping the panels, the clamping frames comprising a base; two chucks, the area of the effective parts of the chucks for clamping the panels can be changed; a tensioning mechanism, the tensioning mechanism being arranged at the upper end of the base, the tensioning mechanism being used to apply opposite pulling forces to the two chucks; a control mechanism, the control mechanism being able to change the size of the effective area of the chucks through the size of the pulling force applied to the chucks by the tensioning mechanism; the present invention enables the chucks to adapt to panels of different weights without the need for external gaskets, effectively reduces the number of steps in the clamping process, avoids the storage loss of the gaskets, and at the same time, because the chucks themselves can meet the protective effect of clamping the panels, effectively avoids the occurrence of panel damage problems caused by missing or misplacing gaskets in the traditional clamping process.

Description

Technical Field

[0001] The invention relates to the technical field of plate painting, in particular to a wax oil coating device for surface treatment of solid wood furniture plates. Background Art

[0002] During the surface treatment of the board, in order to facilitate the transportation of the board and the drying of the coating wax, it is generally necessary to clamp the side wall of the board that is not coated. During the clamping process, in order to protect the board, gaskets such as wooden blocks are often placed between the board and the chuck to increase the pressure area of the side wall of the board and reduce the pressure on the board.

[0003] In the traditional clamping method, the gasket and the chuck are independent of each other, and the gasket made of materials such as wood blocks is easily damaged. This leads to the gasket being easily damaged in the actual production process. At the same time, during the clamping process, the gasket is placed between the plate and the chuck later, and this process is mostly done manually. This leads to the plate being subjected to excessive pressure due to human factors such as missing gaskets during the clamping process, resulting in damage to the plate. Summary of the Invention

[0004] The purpose of the present invention is to provide a wax oil coating device for the surface treatment of solid wood furniture panels, so as to solve the traditional clamping method proposed in the above-mentioned background technology. Since the gasket and the chuck are independent of each other, and the gasket made of materials such as wooden blocks is easily damaged, the gasket is prone to loss in the actual production process. At the same time, during the clamping process, the gasket is placed between the panel and the chuck later, and this process is mostly done manually. This leads to the problem that the panel may be subjected to excessive pressure due to human factors such as missing gaskets during the clamping process, resulting in damage to the panel.

[0005] To achieve the above-mentioned object, the present invention provides the following technical solution: a wax oil coating device for surface treatment of solid wood furniture panels, comprising a loading device, a spraying device and a unloading device, and also comprising a plurality of clamping frames for clamping the panels, wherein the clamping frames include a base;

[0006] Two chucks, the two chucks are symmetrically and longitudinally slidably arranged on the front and rear sides of the base, the chucks are used to clamp the side walls of the plate, and the effective area of the chucks for clamping the plate can be changed;

[0007] A tensioning mechanism, the tensioning mechanism being arranged at the upper end of the base and being used to apply a pulling force toward the two clamps;

[0008] The control mechanism is used to adjust the pulling force of the tensioning mechanism. The control mechanism can change the size of the clamping action part area by applying the pulling force to the clamp by the tensioning mechanism.

[0009] Furthermore, the chuck includes a mounting shell, and the tension provided by the tensioning mechanism acts on the mounting shell. The mounting shell is open on one side close to the tensioning mechanism and is provided with a sliding rod for transverse sliding. A driving mechanism is provided in the mounting shell, and the driving mechanism is transmission-connected to the sliding rod. The driving mechanism is used to drive the sliding rod to move rightward. The mounting shell is rotatably provided with a reel, and the reel is wound with rubber. The rubber extends from the right side of the open end of the mounting shell, wraps around the sliding rod away from the side of the mounting shell, and is fixed to the left side of the open end of the mounting shell; the sliding rod passes through the side wall of the rubber end.

[0010] Furthermore, the mounting shell contains a plurality of mutually hinged sliders, each of which can engage with the side of the mounting shell close to the inner cavity of the mounting shell. The rightmost slider is fixedly connected to the right end of the slide rod, and the driving mechanism is used to drive a slider engaged with the slide rod to move to the right.

[0011] Furthermore, the upper and lower inner walls of the mounting shell are fixedly connected with engaging plates, and the upper and lower side walls of the sliding rod are respectively connected with the upper and lower engaging plates in a transverse sliding manner.

[0012] Furthermore, the driving mechanism includes a vertically arranged first rotating shaft, the upper end of the first rotating shaft is vertically penetrated in the mounting shell and is rotatably connected to the mounting shell, a gear is rotatably connected between the upper and lower clamping plates, the first rotating shaft penetrates the clamping plates and is coaxially fixedly connected to the gear; teeth are provided on the side of the slider close to the gear, the gear can engage with the slider through the teeth, and the gear is always engaged with a slider engaged on the slide rod; the first rotating shaft is transmission-connected to the control mechanism.

[0013] Furthermore, a storage box is fixedly connected to the mounting shell, the opening of the storage box faces and is close to the side wall of the slide bar, and multiple sliders that are not engaged with the slide bar are located in the storage box. The inner cavity of the storage box is only large enough for arranging and storing the sliders.

[0014] Furthermore, the reel is elastically rotatably connected to the mounting shell via an external elastic element.

[0015] Furthermore, the tensioning mechanism includes two mounting plates longitudinally slidably connected to the upper end of the base, a spring is fixedly connected between the two mounting plates, and a screw is longitudinally provided through the two mounting plates, the screw is threadedly connected to the mounting plates, and the screw is transmission-connected to the control mechanism.

[0016] Furthermore, the control mechanism includes two connecting plates longitudinally slidably connected to the upper end of the base, the upper ends of the two connecting plates are fixedly connected to the front and rear mounting shells respectively, a second rotating shaft is longitudinally penetrated by the connecting plate, the second rotating shaft is rotatably connected to the connecting plate, the second rotating shaft is located at the end of the connecting plate away from the tensioning mechanism and is fixedly connected to a hexagonal screw head, the end of the second rotating shaft close to the tensioning mechanism is fixedly connected to the corresponding screw end, the lower end of the first rotating shaft is fixedly connected to the first bevel gear, the side walls of the second rotating shaft are fixedly connected to the second bevel gear, and the first bevel gear is meshed with the second bevel gear.

[0017] Furthermore, the threads of the two screw rods are opposite to each other, and a connecting rod is slidably connected between the two screw rods, and the connecting rod is slidably connected to the axis of the screw rods.

[0018] Furthermore, the second rotating shaft is a telescopic shaft and is provided with a locking device, which can fix the length of the second rotating shaft.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The present invention adopts a chuck that can increase the area of the side wall of the plate by increasing its own clamping force on the plate, so that the chuck can adapt to plates of different weights without the need for external gaskets. Further, the clamping process of the plate avoids the involvement of gaskets, effectively reduces the steps of the clamping process, and avoids the storage loss of gaskets. At the same time, because the chuck itself can meet the protective effect of clamping the plate, it effectively avoids the problem of plate damage caused by missing or misplaced gaskets in the traditional clamping process.

[0021] 2. The present invention clamps the side wall of the plate by squeezing the rubber through the slide bar, and increases the overlapping area between the slide bar and the rubber by moving the slide bar to the right, thereby increasing the pressure area of the side wall of the plate. This method has a simple principle and a simple structure, which makes it highly stable and easy to repair and maintain. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0023] Figure 2 This is a schematic diagram of the structure of the clamping frame clamping the plate;

[0024] Figure 3 Schematic diagram of the structure of the clamping frame;

[0025] Figure 4 for Figure 3 A schematic diagram of the structure at center A;

[0026] Figure 5 This is a schematic diagram of the structure of the clamping frame after the spring is removed;

[0027] Figure 6 Schematic diagram of the structure of the chuck;

[0028] Figure 7 Schematic diagram of the structure after the chuck is removed from the mounting shell.

[0029] In the accompanying drawings: 1-base, 2-loading device, 3-spraying device, 4-unloading device, 5-chuck, 5-1-mounting shell, 5-2-slide rod, 5-3-slider, 5-3-1-tooth, 5-4-reel, 5-5-rubber, 6-first rotating shaft, 7-clamping plate, 8-gear, 9-storage box, 10-mounting plate, 11-screw, 12-connecting plate, 13-second rotating shaft, 14-hexagonal screw head, 15-first bevel gear, 16-second bevel gear, 17-spring, 18-connecting rod. DETAILED DESCRIPTION

[0030] See also Figure 1-Figure 7 The present invention provides a technical solution: a wax oil coating device for surface treatment of solid wood furniture panels, comprising a loading device 2, a spraying device 3 and a unloading device 4, and also comprising a plurality of clamping frames for clamping panels, the clamping frames comprising a base 1;

[0031] Two chucks 5 are symmetrically and longitudinally slidably arranged on the front and rear sides of the base 1, and the chucks 5 are used to clamp the side walls of the plate. The area of the clamping portion of the chuck 5 for clamping the plate can be changed;

[0032] A tensioning mechanism is provided at the upper end of the base 1 and is used to apply a pulling force toward the two clamps 5;

[0033] The control mechanism is used to adjust the pulling force of the tensioning mechanism. The control mechanism can change the size of the active area of the clamp 5 by applying the pulling force to the clamp 5 through the tensioning mechanism.

[0034] (The supporting mechanisms of the feeding device 2, the spraying device 3 and the unloading device 4 and their related driving motors are not shown) During use, the plate is first placed on the upper end of the feeding device 2 (the feeding device 2 is a conventional conveyor belt transfer device), and then the clamping frames are clamped to both ends of the plate, and each plate is clamped with two clamping frames. The clamping process is carried out while the spraying device 3 is spraying wax oil on the plate (this process can be performed manually or with the assistance of an external electric control device). During the clamping process, the tension of the tensioning mechanism is increased by the control mechanism to make The two chucks 5 on a single clamping frame clamp the side wall of the plate. At the same time, under the action of the control mechanism, as the clamping force of the chuck 5 on the side wall of the plate increases, the area of the side wall of the plate squeezed by the chuck 5 increases synchronously. In this way, the pressure of the chuck 5 on the side wall of the plate will not increase due to the increase in the clamping force, further preventing the side wall of the plate from being clamped by the chuck 5. Then the loading device 2 transfers the plate clamped by the clamping frame to the spraying device 3 for wax oil spraying. Finally, the sprayed plate is transferred by the spraying device 3 to the unloading device 4 for delivery equipment to air-dry the wax oil.

[0035] The present invention adopts a chuck 5 that can increase the area of the side wall of the plate by increasing its own clamping force on the plate, so that the chuck 5 can adapt to plates of different weights without the need for external gaskets. Further, the clamping process of the plate avoids the involvement of gaskets, effectively reduces the steps of the clamping process, and avoids the storage loss of gaskets. At the same time, because the chuck 5 itself can meet the protective effect of clamping the plate, it effectively avoids the problem of plate damage caused by missing or misplaced gaskets in the traditional clamping process.

[0036] Furthermore, the chuck 5 includes a mounting shell 5-1, and the tension provided by the tensioning mechanism acts on the mounting shell 5-1. The side of the mounting shell 5-1 close to the tensioning mechanism is open and is provided with a slide rod 5-2 for transverse sliding. A driving mechanism is provided in the mounting shell 5-1, and the driving mechanism is transmission-connected to the slide rod 5-2. The driving mechanism is used to drive the slide rod 5-2 to move to the right. The mounting shell 5-1 is rotatably provided with a reel 5-4, and the reel 5-4 is wound with a rubber 5-5. The rubber 5-5 extends from the right side of the open end of the mounting shell 5-1, wraps around the slide rod 5-2 away from the side of the mounting shell 5-1, and is fixed to the left side of the open end of the mounting shell 5-1; the slide rod 5-2 passes through the side wall of the end of the rubber 5-5.

[0037] During use, the tensioning mechanism applies a pulling force to the mounting shell 5-1 to extrude the plate, so that the mounting shell 5-1 squeezes the slide bar 5-2 toward the plate, and the slide bar 5-2 squeezes the rubber 5-5 toward the plate, so that the rubber 5-5 located on the side of the slide bar 5-2 away from the mounting shell 5-1 squeezes the side wall of the plate. Furthermore, the chuck 5 directly clamps the side wall of the plate through the rubber 5-5 located on the side of the slide bar 5-2 away from the mounting shell 5-1; when the tension provided by the tensioning mechanism increases, the corresponding control mechanism controls the slide bar 5-2 to move to the right through the driving mechanism, and then the right end of the slide bar 5-2 squeezes the side wall of the rubber 5-5, and at the same time, the rubber 5-5 is continuously pulled out of the reel 5-4, so that the rubber 5-5 on the side of the slide bar 5-2 away from the mounting shell 5-1 becomes longer, thereby increasing the area of the active part of the chuck 5 for clamping the plate.

[0038] The present invention clamps the side wall of the plate by squeezing the rubber 5-5 through the slide bar 5-2, and increases the overlapping area between the slide bar 5-2 and the rubber 5-5 by moving the slide bar 5-2 to the right, thereby increasing the pressure area of the side wall of the plate. This method has a simple principle and a simple structure, which makes it highly stable and easy to repair and maintain.

[0039] Since the slide bar 5-2 is exposed outside the mounting housing 5-1, if the slide bar 5-2 is directly driven by the driving mechanism as a transmission member, the slide bar 5-2 is not easily maintained. Therefore, the present invention further proposes the following means:

[0040] Furthermore, the mounting shell 5-1 contains a plurality of mutually hinged sliders 5-3, and the sliders 5-3 can all be engaged with the side of the mounting shell 5-1 close to the inner cavity of the mounting shell 5-1. The rightmost slider 5-3 is fixedly connected to the right end of the slide rod 5-2, and the driving mechanism is used to drive a slider 5-3 engaged with the slide rod 5-2 to move to the right.

[0041] The driving mechanism drives a slider 5-3 engaged with the slide bar 5-2 to move to the right, so that the slider 5-3 pushes the slide bar 5-2 to slide to the right. The slider 5-3, which directly receives the transmission of the driving mechanism, is always located in the mounting shell 5-1, so that the transmission components of the device can be well protected to prevent contamination by external impurities, which may cause adhesion, jamming and other faults between the transmission components.

[0042] Furthermore, the upper and lower inner walls of the mounting shell 5 - 1 are fixedly connected with the clamping plates 7 , and the upper and lower side walls of the slide rod 5 - 2 are respectively connected with the upper and lower clamping plates 7 in a transverse sliding manner.

[0043] During the clamping process, the mounting shell 5-1 squeezes the clamping plate 7, the clamping plate 7 squeezes the sliding rod 5-2, the sliding rod 5-2 squeezes the rubber 5-5, and the rubber 5-5 clamps the plate.

[0044] Furthermore, the driving mechanism includes a vertically arranged first rotating shaft 6, the upper end of the first rotating shaft 6 is vertically penetrated in the mounting shell 5-1 and is rotatably connected to the mounting shell 5-1, a gear 8 is rotatably connected between the upper and lower clamping plates 7, the first rotating shaft 6 penetrates the clamping plates 7 and is coaxially fixedly connected to the gear 8; teeth 5-3-1 are provided on the side of the slider 5-3 close to the gear 8, the gear 8 can engage with the slider 5-3 through the teeth 5-3-1, and the gear 8 is always engaged with a slider 5-3 engaged on the slide rod 5-2; the first rotating shaft 6 is transmission-connected to the control mechanism.

[0045] The control mechanism drives the gear 8 to rotate through the first rotating shaft 6, and the gear 8 drives the slider 5-3 to rotate.

[0046] Furthermore, a storage box 9 is fixedly connected to the mounting shell 5-1, and the opening of the storage box 9 faces and is close to the side wall of the slide bar 5-2. A plurality of sliders 5-3 that are not engaged with the slide bar 5-2 are located in the storage box 9, and the size of the inner cavity of the storage box 9 is only sufficient for arranging and storing the sliders 5-3.

[0047] The slider 5 - 3 that is not engaged with the slide bar 5 - 2 is limited by the storage box 9 to prevent the slider 5 - 3 from being too high in freedom and causing it to be stuck.

[0048] Furthermore, the reel 5 - 4 is elastically rotatably connected to the mounting shell 5 - 1 via an external elastic element.

[0049] When the reel 5-4 is in use, after the clamping is completed and the slide bar 5-2 is reset, the reel 5-4 rewinds the rubber 5-5 through the elastic force of the elastic element.

[0050] Furthermore, the tensioning mechanism includes two mounting plates 10 longitudinally slidably connected to the upper end of the base 1, a spring 17 is fixedly connected between the two mounting plates 10, and both mounting plates 10 are longitudinally penetrated by a screw 11, the screw 11 is threadedly connected to the mounting plate 10, and the screw 11 is transmission-connected to the control mechanism.

[0051] Furthermore, the control mechanism includes two connecting plates 12 longitudinally slidingly connected to the upper end of the base 1, and the upper ends of the two connecting plates 12 are fixedly connected to the front and rear mounting shells 5-1 respectively. A second rotating shaft 13 is longitudinally penetrated by the connecting plate 12, and the second rotating shaft 13 is rotatably connected to the connecting plate 12. The second rotating shaft 13 is located at the end of the connecting plate 12 away from the tensioning mechanism and is fixedly connected to a hexagonal screw head 14. The end of the second rotating shaft 13 close to the tensioning mechanism is fixedly connected to the corresponding end of the screw 11. The lower end of the first rotating shaft 6 is fixedly connected to the first bevel gear 15, and the side walls of the second rotating shaft 13 are fixedly connected to the second bevel gear 16, and the first bevel gear 15 is meshed with the second bevel gear 16.

[0052] When clamping the plate, first align the two clamps 5 with the side wall of the plate, and then rotate the hexagonal screw head 14, so that the hexagonal screw head 14 drives the second rotating shaft 13 to rotate, and the screw 11 rotates relative to the mounting plate 10, and then the mounting plate 10 moves toward the connecting plate 12 on the same side, so that the two ends of the spring 17 are stretched apart, thereby increasing the pulling force of the spring 17 on the front and rear end mounting plates 10, so that the mounting plate 10 increases the pulling force of the mounting shell 5-1 through the screw 11, the second rotating shaft 13, the hexagonal screw head 14 and the connecting plate 12. At the same time, correspondingly, the second rotating shaft 13 rotates to drive the second bevel gear 16 to rotate, and the second bevel gear 16 drives the first bevel gear 15 to rotate, and then drives the gear 8 to move the slide bar 5-2 to the right, thereby increasing the clamping area.

[0053] Furthermore, the threads of the two screw rods 11 are opposite to each other, and a connecting rod 18 is slidably connected between the two screw rods 11 . The connecting rod 18 is slidably connected at the axis of the screw rods 11 .

[0054] In this way, when clamping the plate, it is only necessary to rotate the hexagonal screw head 14 on one side to make the two screws 11 rotate synchronously, so that the two clamps 5 are pressed toward each other.

[0055] Furthermore, the second rotating shaft 13 is a telescopic shaft and is provided with a locking device, which can fix the length of the second rotating shaft 13.

[0056] Before clamping the plate, the distance between the two clamps 5 is adjusted by changing the length of the second rotating shaft 13 so that the two clamps 5 are close to the side wall of the plate, and then the length of the second rotating shaft 13 is locked for subsequent clamping operations.

Claims

1. A wax coating device for surface treatment of solid wood furniture panels, comprising a loading device (2), a spraying device (3) and a unloading device (4), and also comprising a plurality of clamping frames for clamping panels, characterized in that: The clamping frame includes a base (1); two clamps (5), the two clamps (5) are symmetrically and longitudinally slidably arranged on the front and rear sides of the base (1), the clamps (5) are used to clamp the side walls of the plate, and the area of the clamps (5) used to clamp the plate can be changed; a tensioning mechanism, the tensioning mechanism is arranged at the upper end of the base (1), and the tensioning mechanism is used to apply opposite pulling forces to the two clamps (5); a control mechanism, the control mechanism is used to adjust the pulling force of the tensioning mechanism, and the control mechanism can change the area of the clamps (5) by applying the pulling force to the clamps (5) through the tensioning mechanism. The chuck (5) includes a mounting shell (5-1), the tensioning force provided by the tensioning mechanism acts on the mounting shell (5-1), the mounting shell (5-1) is open on one side close to the tensioning mechanism and is provided with a slide rod (5-2) for transverse sliding, a driving mechanism is provided in the mounting shell (5-1), the driving mechanism is in transmission connection with the slide rod (5-2), the driving mechanism is used to drive the slide rod (5-2) to move rightward, the mounting shell (5-1) is provided with a reel (5-4) for rotation, the reel (5-4) is wound with a rubber sheet (5-5), the rubber sheet (5-5) extends from the right side of the open end of the mounting shell (5-1), wraps around the slide rod (5-2) away from the side of the mounting shell (5-1), and is fixed to the left side of the open end of the mounting shell (5-1); the slide rod (5-2) passes through the side wall of the end of the rubber sheet (5-5).

2. The wax oil coating device for surface treatment of solid wood furniture panels according to claim 1, characterized in that: The mounting shell (5-1) contains a plurality of mutually hinged sliders (5-3), each of which is capable of engaging with a side of the mounting shell (5-1) close to the inner cavity of the mounting shell (5-1), with the rightmost slider (5-3) being fixedly connected to the right end of the slide bar (5-2), and the driving mechanism being used to drive a slider (5-3) engaged with the slide bar (5-2) to move rightward.

3. The wax oil coating device for surface treatment of solid wood furniture panels according to claim 2, characterized in that: The upper and lower inner walls of the installation shell (5-1) are fixedly connected with a clamping plate (7), and the upper and lower side walls of the slide rod (5-2) are respectively connected to the upper and lower clamping plates (7) in a transverse sliding manner.

4. The wax oil coating device for surface treatment of solid wood furniture panels according to claim 3, characterized in that: The driving mechanism comprises a first rotating shaft (6) arranged vertically, the upper end of the first rotating shaft (6) vertically passing through the mounting shell (5-1) and being rotatably connected to the mounting shell (5-1), a gear (8) being rotatably connected between the upper and lower clamping plates (7), the first rotating shaft (6) passing through the clamping plates (7) and being coaxially fixedly connected to the gear (8); teeth (5-3-1) are provided on the side of the slider (5-3) close to the gear (8), the gear (8) can be engaged with the slider (5-3) through the teeth (5-3-1), and the gear (8) is always engaged with a slider (5-3) engaged on the slide rod (5-2); the first rotating shaft (6) is in transmission connection with the control mechanism.

5. The wax oil coating device for surface treatment of solid wood furniture panels according to claim 2, characterized in that: A storage box (9) is fixedly connected to the mounting shell (5-1), the opening of the storage box (9) faces and is close to the side wall of the slide bar (5-2), and a plurality of sliders (5-3) that are not engaged with the slide bar (5-2) are located in the storage box (9), and the inner cavity of the storage box (9) is only large enough for arranging and storing the sliders (5-3).

6. The wax oil coating device for surface treatment of solid wood furniture panels according to claim 1, characterized in that: The reel (5-4) is elastically rotatably connected to the mounting shell (5-1) via an external elastic element.

7. The wax oil coating device for surface treatment of solid wood furniture panels according to claim 4, characterized in that: The tensioning mechanism comprises two mounting plates (10) longitudinally slidably connected to the upper end of the base (1), a spring (17) being fixedly connected between the two mounting plates (10), a screw rod (11) being longitudinally passed through the two mounting plates (10), the screw rod (11) being threadedly connected to the mounting plates (10), and the screw rod (11) being transmission-connected to the control mechanism.

8. The wax oil coating device for surface treatment of solid wood furniture panels according to claim 7, characterized in that: The control mechanism comprises two connecting plates (12) connected longitudinally and slidingly to the upper end of the base (1), the upper ends of the two connecting plates (12) are fixedly connected to the front and rear mounting shells (5-1) respectively, a second rotating shaft (13) is longitudinally provided through the connecting plate (12), the second rotating shaft (13) is rotatably connected to the connecting plate (12), the second rotating shaft (13) is located at an end of the connecting plate (12) away from the tensioning mechanism and is fixedly connected to a hexagonal screw head (14), the end of the second rotating shaft (13) close to the tensioning mechanism is fixedly connected to the corresponding end of the screw (11), the lower end of the first rotating shaft (6) is fixedly connected to a first bevel gear (15), the side walls of the second rotating shaft (13) are fixedly connected to second bevel gears (16), and the first bevel gear (15) is meshed with the second bevel gear (16).

9. The wax oil coating device for surface treatment of solid wood furniture panels according to claim 8, characterized in that: The threads of the two screw rods (11) are opposite to each other, and a connecting rod (18) is slidably connected between the two screw rods (11), and the connecting rod (18) is slidably connected at the axis of the screw rods (11); the second rotating shaft (13) is a telescopic shaft and is provided with a locking device, and the locking device can fix the length of the second rotating shaft (13).

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