Stage lamp rocker arm capable of accurately adjusting angle

Abstract

The invention discloses a stage lamp rocker arm capable of accurately adjusting the angle, and relates to the technical field of stage lamps, the stage lamp rocker arm comprises a hollow base stage lamp main body and a rocker arm structure, and the hollow base stage lamp main body is sequentially connected with a first bearing seat stage lamp main body and a second bearing seat stage lamp main body through a height adjusting structure; the rocker arm structure comprises a hollow rocker arm stage lamp body rotationally installed between the first bearing seat stage lamp body and the second bearing seat stage lamp body, an angle self-locking assembly, a driving assembly and a rotating power conversion assembly. The angle self-locking assembly is arranged, the telescopic end of a micro electric push rod is controlled by a microcontroller to extend to push a pawl upwards so that the pawl can be meshed with a ratchet wheel to achieve the one-way self-locking effect, and then the stability of the stage lamp rocker arm after angle adjustment is completed can be guaranteed; by means of the innovative structure, the accuracy of angle adjustment of the stage lamp rocker arm is effectively improved, and the speed reduction effect cannot be generated in the angle adjustment process.

Description

Technical Field

[0001] The present invention relates to the technical field of stage lights, and in particular to a stage light boom with precise angle adjustment. Background Art

[0002] During the use of stage lights, a stage light boom is needed to dynamically adjust the angle of the stage lights to better create the effect of dynamic stage lighting.

[0003] After retrieval, the patent with the application number 202323261558.9 discloses a stage light boom and a stage light, which includes a boom main body, on which a lamp mounting component for mounting a lamp is rotatably connected. The stage light boom further includes a first driving device and a second driving device. The first driving device is arranged on the boom main body, and its driving end is connected to the lamp mounting component through a first worm and worm gear transmission mechanism to drive the lamp mounting component and the lamp to rotate.

[0004] This prior art relies on a worm and worm gear transmission mechanism for transmission, which can effectively improve the accuracy of angle adjustment. However, such a transmission structure will produce a deceleration phenomenon when adjusting the angle, affecting the speed and efficiency of adjustment, and is not convenient for better creating the effect of dynamic stage lighting. Moreover, during the rotation adjustment process of the existing stage light boom, the rotational power will be directly lost and wasted without being effectively utilized. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the present invention provides a stage light boom with precise angle adjustment, effectively solving the problem that the existing stage light boom often uses a worm and worm gear transmission method to increase the self-locking performance in order to ensure the accuracy of adjustment. Such a transmission structure produces a deceleration phenomenon when adjusting the angle, affecting the speed and efficiency of adjustment, and is not convenient for better creating the effect of dynamic stage lighting. It also effectively solves the problem that during the rotation adjustment process of the existing stage light boom, the rotational power will be directly lost and wasted without being effectively utilized.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A stage light boom with precise angle adjustment includes a hollow base stage light main body and a boom structure. The hollow base stage light main body is sequentially connected with a first bearing seat stage light main body and a second bearing seat stage light main body through a height adjustment structure. A fixed cover stage light main body is fixedly connected to the side wall of the first bearing seat stage light main body, and an air supply cover stage light main body is fixedly connected to the side wall of the second bearing seat stage light main body;

[0008] The rocker arm structure includes a hollow rocker arm stage light body rotatably installed between a first bearing seat stage light body and a second bearing seat stage light body, an angle self-locking component, a driving component, and a rotational power conversion component. A stage light connection seat stage light body stage light body is fixedly connected to the hollow rocker arm stage light body, and a stage light body stage light body stage light body is fixedly installed on the top outer wall of the stage light connection seat stage light body stage light body;

[0009] The angle self-locking component includes a ratchet wheel stage light body fixedly sleeved at one end of the hollow rocker arm stage light body, a pawl stage light body hinged to the inner wall of the back surface of the fixed cover stage light body, and a micro electric push rod stage light body hinged to the inner wall of the bottom of the fixed cover stage light body;

[0010] The rotational power conversion component includes a blower fan blade stage light body stage light body fixedly sleeved in another region at the other end of the hollow rocker arm stage light body, an air inlet cover stage light body stage light body fixedly communicated with another port of the hollow rocker arm stage light body, a rotary joint stage light body stage light body, and a connecting pipe stage light body stage light body fixedly communicated with one side of the air supply cover stage light body.

[0011] As a preferred technical solution of the present invention, the micro electric push rod stage light body is inclined, the telescopic end of the micro electric push rod stage light body is hinged to the pawl stage light body, and the ratchet wheel stage light body and the pawl stage light body are engaged with each other and are both located in the fixed cover stage light body.

[0012] As a preferred technical solution of the present invention, a connecting spring stage light body stage light body is fixedly connected to the inner wall of the back surface of the fixed cover stage light body through a spring support stage light body stage light body, and the top end of the connecting spring stage light body stage light body is fixed to the pawl stage light body.

[0013] As a preferred technical solution of the present invention, the driving component includes a stepping motor stage light body stage light body fixedly installed on the side wall of the fixed cover stage light body, a driving gear stage light body stage light body fixedly sleeved on the output shaft of the stepping motor stage light body stage light body, and a transmission gear stage light body stage light body fixedly sleeved at one end of the hollow rocker arm stage light body.

[0014] As a preferred technical solution of the present invention, the output shaft of the stepper motor stage light main body penetrates through one side of the fixed cover of the stage light main body. The driving gear of the stage light main body meshes with the transmission gear of the stage light main body, and both are located inside the fixed cover of the stage light main body. A microcontroller of the stage light main body is fixedly installed on the front outer wall of the fixed cover of the stage light main body. And the stepper motor of the stage light main body and the micro electric push rod of the stage light main body are both electrically connected to the microcontroller of the stage light main body.

[0015] As a preferred technical solution of the present invention, the rotating part of the rotary joint of the stage light main body is hermetically and fixedly communicated with the air supply cover of the stage light main body, and the fixed part of the rotary joint of the stage light main body is hermetically and fixedly communicated with one end of the connecting pipe of the stage light main body extending into the air supply cover of the stage light main body.

[0016] As a preferred technical solution of the present invention, heat dissipation fins are fixedly embedded at the top of the stage light connection seat of the stage light main body. Blow holes are arranged at equal intervals in the connection area between the hollow swing arm of the stage light main body and the stage light connection seat of the stage light main body. And an air inlet hole is arranged at the front of the air supply cover of the stage light main body.

[0017] As a preferred technical solution of the present invention, the height adjustment structure includes two fixed square tubes symmetrically fixed on the top outer wall of the hollow base of the stage light main body, two lifting adjustment lead screws sequentially arranged in the two fixed square tubes of the stage light main body, two lifting brackets sequentially threadedly connected to the two lifting adjustment lead screws of the stage light main body, a servo motor fixedly installed on the top middle outer wall of the hollow base of the stage light main body, and a synchronous transmission component arranged inside the hollow base of the stage light main body.

[0018] As a preferred technical solution of the present invention, the bottom ends of the two lifting adjustment lead screws of the stage light main body are both connected through bearings to the top inner wall of the hollow base of the stage light main body. The outer walls of the two lifting brackets of the stage light main body are respectively slidably connected to the inner walls of the two fixed square tubes of the stage light main body. And the first bearing seat of the stage light main body and the second bearing seat of the stage light main body are respectively fixedly connected to the top outer walls of the two lifting brackets of the stage light main body.

[0019] As a preferred technical solution of the present invention, the synchronous transmission assembly includes a double-slot synchronous wheel stage light body stage light body fixedly mounted on the output shaft of the servo motor stage light body stage light body and two single-slot synchronous wheel stage light body stage light body fixedly mounted on the bottom ends of the two lifting adjustment screws stage light body stage light body in sequence, and the double-slot synchronous wheel stage light body stage light body is sequentially connected to the two single-slot synchronous wheel stage light body stage light body through two synchronous belts stage light body stage light body.

[0020] The beneficial effects of the present invention are:

[0021] 1. The present invention is provided with an angle self-locking component. The micro-controller controls the telescopic end of the micro-electric push rod to extend and push the pawl upward to engage with the ratchet wheel to form a one-way self-locking effect, thereby ensuring the stability of the stage light rocker arm after the angle adjustment is completed. Therefore, this innovative structure not only effectively improves the accuracy of the stage light rocker arm angle adjustment, but also does not produce a deceleration effect during the angle adjustment process, making the stage light rocker arm angle adjustment faster and more efficient, which is conducive to better creating the effect of dynamic stage lighting;

[0022] 2. The present invention is provided with a rotational power conversion assembly, which can convert the rotational power of the hollow swing arm into the rotational power of the fan blades during the stage light angle adjustment process to generate air flow blowing toward the surface of the heat dissipation fins to improve the heat dissipation efficiency of the stage light, thereby effectively utilizing the rotational power of the entire swing arm structure;

[0023] 3. The present invention is provided with a height adjustment structure, which drives the double-groove synchronous wheel to rotate through a servo motor. Then, under the synchronous transmission effect of the two synchronous belts, the two lifting adjustment screws will rotate synchronously, causing the two lifting brackets that are threaded with them to move upward synchronously, thereby being able to flexibly adjust the installation height of the rocker arm structure, so as to better adapt to the use of stage lights of different height specifications. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly describes the drawings required for the specific embodiments or the description of the prior art. Similar elements or parts are generally identified by similar reference numerals throughout the drawings. Elements or parts in the drawings are not necessarily drawn to scale.

[0025] Figure 1 It is a schematic diagram of the overall three-dimensional structure of the present invention;

[0026] Figure 2 This is a front view structural diagram of the air supply cover of the present invention in a vertical cross-section state;

[0027] Figure 3Schematic diagram of the three-dimensional enlarged structure of the rocker arm structure of the present invention;

[0028] Figure 4 Schematic diagram of the three-dimensional enlarged structure inside the fixed cover of the present invention;

[0029] Figure 5 Schematic diagram of the side view structure inside the fixed cover of the present invention;

[0030] Figure 6 Schematic diagram of the three-dimensional enlarged structure inside the air supply cover of the present invention;

[0031] Figure 7 Schematic diagram of the three-dimensional enlarged structure of local parts of the present invention;

[0032] Figure 8 Schematic diagram of the three-dimensional enlarged structure of the partial section of the height adjustment structure of the present invention.

[0033] In the figure: 1, hollow base; 2, first bearing seat; 3, second bearing seat; 4, fixed cover; 5, air supply cover; 6, hollow rocker arm; 7, ratchet wheel; 8, ratchet pawl; 9, micro electric push rod; 10, spring support; 11, connecting spring; 12, micro controller; 13, stepping motor; 14, driving gear; 15, transmission gear; 16, air supply fan blade; 17, air inlet cover; 18, connecting pipe; 19, rotary joint; 20, stage light connection seat; 21, heat dissipation fin; 22, air blowing hole; 23, stage light main body; 24, fixed square pipe; 25, lifting adjustment lead screw; 26, lifting bracket; 27, servo motor; 28, double groove synchronous pulley; 29, single groove synchronous pulley; 30, synchronous belt; 31, air inlet hole. Detailed implementation manners

[0034] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0035] Example 1, referring to Figures 1-5 , a stage light rocker arm with precise angle adjustment, including a hollow base 1 and a rocker arm structure. The purpose of this embodiment is to solve the problem that in order to ensure the accuracy of adjustment, the existing stage light rocker arms often use the worm and worm gear transmission method to increase the self-locking performance. Such a transmission structure generates a deceleration phenomenon when adjusting the angle, affecting the adjustment speed and efficiency, and is not convenient for better creating the effect of stage dynamic lighting.

[0036] In this embodiment, a first bearing seat 2 and a second bearing seat 3 are sequentially connected to the hollow base 1 through a height adjustment structure. A fixed cover 4 is fixedly connected to the side wall of the first bearing seat 2, and an air supply cover 5 is fixedly connected to the side wall of the second bearing seat 3;

[0037] Furthermore, the rocker arm structure includes a hollow rocker arm 6 rotatably mounted between a first bearing block 2 and a second bearing block 3, an angle self-locking assembly, a driving assembly, and a rotational power conversion assembly. A stage light connection base 20 is fixedly connected to the hollow rocker arm 6, and a stage light main body 23 is fixedly mounted on the top outer wall of the stage light connection base 20;

[0038] Furthermore, the angle self-locking assembly includes a ratchet wheel 7 fixedly sleeved at one end of the hollow rocker arm 6, a pawl 8 hinged to the inner wall of the back surface of the fixed cover 4, and a micro electric push rod 9 hinged to the inner wall of the bottom of the fixed cover 4;

[0039] Furthermore, the micro electric push rod 9 is inclined. The telescopic end of the micro electric push rod 9 is hinged to the pawl 8. The ratchet wheel 7 and the pawl 8 are engaged with each other and are both located inside the fixed cover 4. A connecting spring 11 is fixedly connected to the inner wall of the back surface of the fixed cover 4 through a spring support 10, and the top end of the connecting spring 11 is fixed to the pawl 8;

[0040] Furthermore, the driving assembly includes a stepping motor 13 fixedly mounted on the side wall of the fixed cover 4, a driving gear 14 fixedly sleeved on the output shaft of the stepping motor 13, and a transmission gear 15 fixedly sleeved at one end of the hollow rocker arm 6. The output shaft of the stepping motor 13 penetrates through one side of the fixed cover 4. The driving gear 14 and the transmission gear 15 are engaged with each other and are both located inside the fixed cover 4. A micro controller 12 is fixedly mounted on the front outer wall of the fixed cover 4. The stepping motor 13 and the micro electric push rod 9 are both electrically connected to the micro controller 12;

[0041] In the specific use of this embodiment: when it is necessary to adjust the angle of the stage light main body 23, the telescopic end of the micro electric push rod 9 is controlled by the micro controller 12 to contract and pull the pawl 8 downward to separate it from the ratchet wheel 7. At this time, the micro controller 12 will control the stepping motor 13 to work. The stepping motor 13 controls the driving gear 14 to rotate. Subsequently, the transmission gear 15 engaged with the driving gear 14 will drive the hollow rocker arm 6 to rotate a certain angle to adjust the angle of the stage light main body 23 installed on the stage light connection base 20. After the angle adjustment is completed, the micro controller 12 will control the telescopic end of the micro electric push rod 9 to extend and push the pawl 8 upward to make it engage with the ratchet wheel 7 again. In this way, after the angle adjustment is completed, through the one-way self-locking performance after the ratchet wheel 7 and the pawl 8 are engaged, the stability after the angle adjustment of the stage light rocker arm can be ensured. Therefore, this innovative structure not only effectively improves the accuracy of the angle adjustment of the stage light rocker arm, but also does not produce a deceleration effect during the angle adjustment process, enabling the angle adjustment of the stage light rocker arm to be carried out more quickly and efficiently, which is conducive to better creating the effect of the stage dynamic lighting.

[0042] Example 2, referring to Figures 1-3 and Figures 6-7, This embodiment is an optimization based on Embodiment 1, aiming to solve the problem that during the rotation adjustment of the existing stage light rocker arm, the rotation power will be directly lost and wasted without being effectively utilized. Specifically: The rotation power conversion component includes a blower fan blade 16 fixedly sleeved on the other end area of the hollow rocker arm 6, an air inlet hood 17 fixedly connected to the other port of the hollow rocker arm 6, a rotary joint 19, and a connecting pipe 18 fixedly connected to one side of the air supply hood 5;

[0043] Further, the rotating part of the rotary joint 19 is fixedly and sealingly connected to the air supply hood 5, and the fixed part of the rotary joint 19 is fixedly and sealingly connected to one end of the connecting pipe 18 extending into the air supply hood 5. Through the transfer effect of the rotary joint 19, it is convenient to supply air to the hollow rocker arm 6 in a rotating state, ensuring the normal progress of the air supply work;

[0044] Further, a heat dissipation fin 21 is fixedly embedded at the top of the stage light connecting seat 20, and equidistantly distributed blowing holes 22 are provided at the connection area between the hollow rocker arm 6 and the stage light connecting seat 20. An air inlet hole 31 is provided at the front of the air supply hood 5;

[0045] When this embodiment is specifically used: When the hollow rocker arm 6 rotates to adjust the angle of the stage light, the blower fan blade 16 located in the air supply hood 5 will automatically rotate, causing the external air flow to enter the air supply hood 5 from the air inlet hole 31. Subsequently, the entering air flow will be continuously sent into the hollow rocker arm 6 from the air inlet hood 17 through the connection and cooperation of the connecting pipe 18 and the rotary joint 19. At this time, the entering air flow will be evenly blown out from the equidistantly distributed blowing holes 22, facilitating the rapid removal of the heat on the surface of the heat dissipation fin 21 and increasing the air convection efficiency around. In this way, during the adjustment of the stage light angle, the rotation power of the hollow rocker arm 6 can be converted into the rotation power of the blower fan blade 16 to generate an air flow blowing towards the surface of the heat dissipation fin 21, thereby improving the heat dissipation efficiency of the stage light, and enabling the effective utilization of the rotation power of the entire rocker arm structure.

[0046] Embodiment 3, referring to Figures 1-2 and Figure 8 , This embodiment is an optimization based on Embodiment 1, aiming to solve the problem that the installation height of the existing rocker arm is fixed and cannot adapt to the use of stage lights with different height specifications. Specifically: The height adjustment structure includes two fixed square tubes 24 symmetrically fixed on the outer wall of the top of the hollow base 1, two lifting adjustment lead screws 25 sequentially arranged in the two fixed square tubes 24, two lifting brackets 26 sequentially threadedly connected to the two lifting adjustment lead screws 25, a servo motor 27 fixedly installed on the outer wall of the middle of the top of the hollow base 1, and a synchronous transmission component arranged in the hollow base 1;

[0047] Further, the bottom ends of the two lifting and adjusting lead screws 25 are respectively connected through bearings to penetrate the inner wall of the top of the hollow base 1, the outer walls of the two lifting brackets 26 are respectively slidably connected to the inner walls of the two fixed square tubes 24, and the first bearing seat 2 and the second bearing seat 3 are respectively fixedly connected to the outer walls of the tops of the two lifting brackets 26;

[0048] Further, the synchronous transmission assembly includes a double-groove synchronous pulley 28 fixedly sleeved on the output shaft of the servo motor 27 and two single-groove synchronous pulleys 29 fixedly sleeved on the bottom ends of the two lifting and adjusting lead screws 25 in sequence. The double-groove synchronous pulley 28 is sequentially connected to the two single-groove synchronous pulleys 29 through two synchronous belts 30 for transmission;

[0049] In the specific use of this embodiment: The servo motor 27 is driven to rotate the double-groove synchronous pulley 28. Subsequently, under the synchronous transmission effect of the two synchronous belts 30, the two lifting and adjusting lead screws 25 will rotate synchronously, so that the two lifting brackets 26 in threaded cooperation with them move upward synchronously, thereby enabling flexible adjustment of the installation height of the rocker arm structure and facilitating better adaptation to stage lights of different height specifications.

[0050] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", "front end", "rear end", "both ends", "one end", "the other end", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance. Moreover, the term "comprising", "including" or any other variation thereof is intended to cover a non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device.

[0051] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A stage light swing arm with precise angle adjustment, comprising a hollow base (1) and a swing arm structure, characterized in that, A first bearing block (2) and a second bearing block (3) are successively connected to the hollow base (1) through a height adjustment structure. A fixed cover (4) is fixedly connected to the side wall of the first bearing block (2), and an air supply cover (5) is fixedly connected to the side wall of the second bearing block (3). The swing arm structure includes a hollow swing arm (6) rotatably installed between the first bearing block (2) and the second bearing block (3), an angle self-locking component, a driving component, and a rotational power conversion component. A stage light connection seat (20) is fixedly connected to the hollow swing arm (6), and a stage light main body (23) is fixedly installed on the outer wall of the top of the stage light connection seat (20). The angle self-locking component includes a ratchet wheel (7) fixedly sleeved at one end of the hollow swing arm (6), a pawl (8) hinged to the inner wall of the back surface of the fixed cover (4), and a micro electric push rod (9) hinged to the inner wall of the bottom of the fixed cover (4). The rotational power conversion component includes a blower fan blade (16) fixedly sleeved in another region at the other end of the hollow swing arm (6), an air inlet cover (17) fixedly communicated with the other port of the hollow swing arm (6), a rotary joint (19), and a connecting pipe (18) fixedly communicated with one side of the air supply cover (5).

2. The stage light swing arm with precisely adjustable angle according to claim 1, wherein The micro electric push rod (9) is obliquely arranged. The telescopic end of the micro electric push rod (9) is hinged to the pawl (8), and the ratchet wheel (7) and the pawl (8) are engaged with each other and are both located in the fixed cover (4).

3. The stage light rocker arm with precisely adjustable angle according to claim 1, characterized in that, A connecting spring (11) is fixedly connected to the inner wall of the back surface of the fixed cover (4) through a spring support (10), and the top end of the connecting spring (11) is fixed to the pawl (8).

4. A stage light rocker arm with precisely adjustable angle according to claim 1, characterized in that, The driving component includes a stepping motor (13) fixedly installed on the side wall of the fixed cover (4), a driving gear (14) fixedly sleeved on the output shaft of the stepping motor (13), and a transmission gear (15) fixedly sleeved at one end of the hollow swing arm (6).

5. A stage light swing arm with precisely adjustable angle according to claim 4, characterized in that, The output shaft of the stepping motor (13) penetrates through one side of the fixed cover (4). The driving gear (14) and the transmission gear (15) are engaged with each other and are both located in the fixed cover (4). A micro controller (l2) is fixedly installed on the outer wall of the front side of the fixed cover (4), and the stepping motor (13) and the micro electric push rod (9) are both electrically connected to the micro controller (12).

6. The stage light swing arm with precisely adjustable angle according to claim 1, characterized in that, The rotating part of the rotary joint (19) is hermetically and fixedly communicated with the air supply cover (5), and the fixed part of the rotary joint (19) is hermetically and fixedly communicated with one end of the connecting pipe (18) extending into the air supply cover (5).

7. The swing arm of a stage light with precisely adjustable angle according to claim 1, characterized in that, A heat dissipation fin (21) is fixedly embedded in the top of the stage light connection seat (20). Blow holes (22) are arranged at equal distances at the connection area between the hollow swing arm (6) and the stage light connection seat (20), and an air inlet hole (31) is arranged at the front side of the air supply cover (5).

8. A stage light swing arm with precisely adjustable angle according to claim 1, characterized in that The height adjustment structure comprises two fixed square tubes (24) symmetrically fixed to the outer wall of the top of the hollow base (1), two lifting adjustment screws (25) arranged in sequence in the two fixed square tubes (24), two lifting brackets (26) threadedly connected to the two lifting adjustment screws (25) in sequence, a servo motor (27) fixedly mounted on the outer wall of the middle of the top of the hollow base (1), and a synchronous transmission assembly arranged in the hollow base (1).

9. The stage light rocker arm with precisely adjustable angle according to claim 8, characterized in that, The bottom ends of the two lifting adjustment screws (25) are connected to the top inner wall of the hollow base (1) through bearings, the outer walls of the two lifting brackets (26) are respectively slidably connected to the inner walls of the two fixed square tubes (24), and the first bearing seat (2) and the second bearing seat (3) are respectively fixedly connected to the top outer walls of the two lifting brackets (26).

10. The stage light swing arm with precisely adjustable angle according to claim 8, characterized in that, The synchronous transmission assembly comprises a double-groove synchronous wheel (28) fixedly mounted on the output shaft of the servo motor (27) and two single-groove synchronous wheels (29) fixedly mounted on the bottom ends of the two lifting adjustment screws (25) in sequence, and the double-groove synchronous wheel (28) is sequentially connected to the two single-groove synchronous wheels (29) through two synchronous belts (30).

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