Universal PCBA (Printed Circuit Board Assembly) clamping device for high-speed optical module
By designing a PCBA board clamping device with adjustable spacing, the special design problems of PCBA board clamping devices of different sizes are solved, versatility and cost savings are achieved, and the R&D cycle is shortened.
Patent Information
- Application Number
- CN202422679759.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-04
- Publication Date
- 2025-09-02
- Estimated Expiration
- 2034-11-04
AI Technical Summary
In the prior art, special clamping devices are required for PCBA boards of different sizes, resulting in increased design workload, extended cycles and waste of special fixtures, which cannot meet the needs of rapid response and cost control.
A universal clamping device including a base, a sliding seat, a first clamping assembly and a second clamping assembly is designed. By adjusting the spacing between the first clamping assembly and the second clamping assembly, it can adapt to the clamping requirements of different sizes of PCBA plates, and use a locking structure and a guide rail assembly to achieve reliable connection, and use a threaded connection and a clamping structure to achieve adjustable clamping.
It improves the versatility of the clamping device, reduces repeated designs, saves costs, shortens the R&D cycle of new projects, and is suitable for use in multiple links.
Smart Images

Figure CN223289673U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of PCBA board clamping tooling, in particular to a universal PCBA board clamping device for high-speed optical modules. Background Art
[0002] The production and repair process of high-speed optical modules requires the use of a large number of jigs and devices for support and clamping. The most common part of these jigs and devices is the clamping of the PCBA board.
[0003] In conventional designs, specialized clamping devices are designed for PCBAs of varying sizes. Specifically, specialized clamping devices are designed for different projects and PCBAs of varying sizes and layouts to support and clamp the boards during fabrication and rework. Due to the large number of product lines and the rapid changes in project plans based on chip supply and market demand, the extensive use of specialized clamping devices, particularly during the prototype design phase, can double the design workload and significantly extend response times. Furthermore, when projects encounter obstacles, a large number of specialized fixtures and devices become unused and wasteful. Therefore, the development of a universal PCBA clamping device is imperative. This can significantly save costs, accelerate R&D and prototype preparation, and reduce design workload—achieving multiple goals at once. Utility Model Content
[0004] The technical problem to be solved by the present invention is to provide a universal PCBA board clamping device for high-speed optical modules, which can clamp PCBA boards of different sizes and types, thereby improving the versatility of the clamping device, speeding up the production process of PCBA boards, and reducing design and development costs.
[0005] The utility model provides a universal PCBA board clamping device for high-speed optical modules, comprising a base, a sliding base, a first clamping assembly and a second clamping assembly; the first clamping assembly is connected to the base, and the second clamping assembly is connected to the sliding base. The sliding base is slidably connected to the base to enable the second clamping assembly to move closer to or away from the first clamping assembly. A locking structure is provided between the sliding base and the base. The first clamping assembly and the second clamping assembly are used to support and clamp two opposite ends of the PCBA board.
[0006] After adopting the above structure, the distance between the first clamping component and the second clamping component can be adjusted in the present invention, so that the PCBA board required for most projects can be clamped and fixed. The present invention has multiple uses and is convenient for use in multiple links such as coupling, testing, board inspection, and rework of new projects, avoiding the repeated design of various types of clamping devices, especially in the sample production stage, which can save a lot of costs. In addition, it can reduce the design workload and shorten the new project research and development cycle. That is, when introducing a new project, it is only necessary to simply adjust the positions of the first clamping component and the second clamping component, so that the new project sample production can be easily carried out.
[0007] In a possible embodiment, the locking structure includes two fixing screws that are symmetrically threaded on both sides of the sliding seat, and the inner end of each fixing screw is used to abut against the base to lock the sliding seat and the base; by adopting this locking structure, when the fixing screw is tightened, that is, the inner end of the fixing screw abuts against the base, the sliding seat and the base can be locked, and the distance between the first clamping component and the second clamping component can be fixed; when the distance between the first clamping component and the second clamping component needs to be adjusted to clamp PCBA boards of different sizes, the fixing screw is loosened, and at this time, the sliding seat can slide relative to the base, thereby achieving the adjustment of the distance between the first clamping component and the second clamping component. When the distance adjustment between the first clamping component and the second clamping component is completed, the fixing screw is tightened again to fix the sliding seat and the base.
[0008] In a possible embodiment, the bottom of the sliding seat is slidably connected to the base through two guide rail assemblies that are symmetrically arranged on the left and right. After adopting this structure, under the action of the guide rail assemblies, the sliding seat can be reliably slidably connected to the base.
[0009] In one possible embodiment, the first clamping assembly includes two left-right symmetrical first clamping blocks and two left-right symmetrical first adjustment units; the two first clamping blocks are slidably connected to the base and can move closer to or farther away from each other, and a clamping groove is provided on the top of the inner side of each first clamping block, and the two clamping grooves are used to support and clamp the two corners at one end of the PCBA board; the two first adjustment units are connected to the base, and the two first clamping blocks are respectively connected to one of the first adjustment units in a transmission manner, and each first adjustment unit is used to drive the corresponding first clamping block to move relative to the base to make the two first clamping blocks move closer to or farther away; After adopting this first clamping assembly, the clamping groove on each first clamping block has two vertical side walls. When the two clamping grooves support and clamp the two corners at one end of the PCBA board, the two side walls of each clamping groove can abut against the two side edges of the corresponding corner of the PCBA board and limit them horizontally. When the two first adjustment units drive the two first clamping blocks closer to each other, the clamping grooves on the two first clamping blocks can clamp one end of the PCBA board. When the two first adjustment units drive the two first clamping blocks away from each other, the two first clamping blocks can release the clamping of one end of the PCBA board.
[0010] In one possible embodiment, the lower end of each first clamp is provided with an inverted "T"-shaped first slider, and the base is provided with an inverted "T"-shaped slide groove corresponding to the first slider one by one, and each first slider is slidably fitted in the slide groove on the corresponding side; by adopting this structure, under the cooperation of the inverted "T"-shaped first slider and the inverted "T"-shaped slide groove, each first clamp can be reliably slidably connected to the base and achieve the purpose of vertical limitation.
[0011] In a possible embodiment, each first adjusting unit includes a screw support and a first hand-tightening screw; the two screw supports are symmetrically fixed on the left and right outer walls of the base, and the screw parts of the two first hand-tightening screws are respectively horizontally inserted into the screw supports on the corresponding sides and threadedly connected to the screw supports; a "T"-shaped first clamping portion is provided on the inner end portion of each first hand-tightening screw, and a "T"-shaped first clamping groove is provided on the top of the outer side of each first clamping block, and each first clamping portion is vertically clamped into the first clamping groove on the corresponding side and rotatably connected to the first clamping groove; after adopting this first adjusting unit, when the first hand-tightening screw is screwed, since the screw part of the first hand-tightening screw is threadedly connected to the base, and since the "T"-shaped first clamping portion on the inner end portion of each first hand-tightening screw is rotatably connected to the "T"-shaped first clamping groove on the first clamping block on the corresponding side, the first clamping block can be conveniently and reliably driven to slide horizontally relative to the base.
[0012] In one possible embodiment, the second clamping assembly includes a connecting seat, two left-right symmetrical second clamping blocks, and two left-right symmetrical second adjustment units; the connecting seat is fixed on the sliding seat, the two second clamping blocks are slidably connected to the connecting seat and can move closer to or farther away from each other, the upper ends of the two second clamping blocks are used to support the left and right sides of the other end of the PCBA board, and the top of the inner side of each second clamping block is provided with a clamping protrusion, and the two clamping protrusions are used to engage with the open grooves on both sides of the other end of the PCBA board and clamp the PCBA board; the two second adjustment units are both connected to the connecting seat, and the two second clamping blocks are respectively connected to one of the second adjustment units in a transmission connection. Then, each second adjustment unit is used to drive the corresponding second clamping block to move relative to the connecting base so that the two second clamping blocks are closer or farther away; after adopting this second clamping assembly, the clamping protrusions on the two second clamping blocks can engage with the open grooves on both sides of the other end of the PCBA board and clamp the PCBA board, and can achieve horizontal limitation of the PCBA board. When the two second adjustment units drive the two second clamping blocks to approach each other, the clamping protrusions on the two second clamping blocks can clamp the other end of the PCBA board. When the two second adjustment units drive the two second clamping blocks to move away from each other, the two second clamping blocks can release the clamping of the other end of the PCBA board.
[0013] In one possible embodiment, a second slider is provided at the lower end of each second clamping block, and a sliding hole vertically corresponding to the second slider is provided on the connecting seat, and each second slider is vertically inserted into the sliding hole on the corresponding side and is horizontally slidably connected to the sliding hole; by adopting this structure, under the cooperative sliding action of the second slider and the sliding hole, each second clamping block can be reliably horizontally slidably connected to the connecting seat.
[0014] In a possible embodiment, the second clamping assembly also includes a guide rod, a guide hole is provided at the lower end of each second slider, the guide rod is passed through the two guide holes, each second slider is slidably connected to the guide rod, and both ends of the guide rod are passed through the connecting seat and tightly fit with the connecting seat; by adopting this structure, under the sliding cooperation of the guide hole and the guide rod, not only can the vertical limiting effect of the second clamping block and the connecting seat be achieved, but also the horizontal sliding of the second slider relative to the connecting seat can be further guided, that is, the reliability of the horizontal sliding connection between the second clamping block and the connecting seat can be further improved.
[0015] In a possible embodiment, each second adjustment unit includes a second hand-tightening screw; the screw portions of the two second hand-tightening screws are horizontally arranged on the left and right ends of the connecting seat and are threadedly connected to the connecting seat; a "T"-shaped second clamping portion is provided on the inner end portion of each second hand-tightening screw, and a "T"-shaped second clamping groove is provided on the top of the outer side of each second clamping block, and each second clamping portion is vertically clamped into the second clamping groove on the corresponding side and is rotatably connected to the second clamping groove; after adopting this second adjustment unit, when the second hand-tightening screw is tightened, since the screw portion of the second hand-tightening screw is threadedly connected to the connecting seat, and since the "T"-shaped second clamping portion on the inner end portion of each second hand-tightening screw is rotatably connected to the "T"-shaped second clamping groove on the second clamping block on the corresponding side, the second clamping block can be conveniently and reliably driven to slide horizontally relative to the connecting seat. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 It is a schematic diagram of the three-dimensional structure of the utility model;
[0017] Figure 2 It is a schematic diagram of a partially exploded three-dimensional structure of the utility model;
[0018] Figure 3 Schematic diagram of the three-dimensional structure of the connecting seat;
[0019] Figure 4 Schematic diagram of the three-dimensional structure of the second clamping block;
[0020] Figure 5 The top view of the PCBA board is shown in Figure 2. DETAILED DESCRIPTION
[0021] First, those skilled in the art should understand that these embodiments are merely used to explain the technical principles of the embodiments of the present application and are not intended to limit the scope of protection of the embodiments of the present application. Those skilled in the art may adjust them as needed to suit specific application scenarios.
[0022] In the description of the embodiments of this application, it should be noted that, unless otherwise specified or limited, the terms "connected" and "connection" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium. Those skilled in the art will understand the specific meanings of the above terms in the embodiments of this application based on the specific circumstances.
[0023] In the embodiments of the present application, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, a first feature being "above," "above," and "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.
[0024] The present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0025] See also Figure 1-5 As shown, an embodiment of the present application discloses a universal PCBA board clamping device for a high-speed optical module, including a base 1, a sliding base 2, a first clamping assembly and a second clamping assembly; the first clamping assembly is connected to the base 1, and the second clamping assembly is connected to the sliding base 2. The sliding base 2 is slidably connected to the base 1 to make the second clamping assembly approach or move away from the first clamping assembly. A locking structure is provided between the sliding base 2 and the base 1. The first clamping assembly and the second clamping assembly are used to support and clamp two opposite ends of the PCBA board 3.
[0026] The locking structure includes two set screws 4 that are symmetrically threaded on both sides of the sliding seat 2, and the inner end of each set screw 4 is used to abut against the base 1 to lock the sliding seat 2 and the base 1; after adopting this locking structure, when the set screw is tightened, that is, the inner end of the set screw abuts against the base, the sliding seat and the base can be locked, and the distance between the first clamping assembly and the second clamping assembly can be fixed; when the distance between the first clamping assembly and the second clamping assembly needs to be adjusted to clamp PCBA boards of different sizes, the set screw is loosened. At this time, the sliding seat can slide relative to the base, thereby adjusting the distance between the first clamping assembly and the second clamping assembly. When the distance between the first clamping assembly and the second clamping assembly is adjusted, the set screw is tightened again to fix the sliding seat and the base.
[0027] The bottom of the sliding seat 2 is slidably connected to the base 1 through two guide rail assemblies 5 that are symmetrically arranged on the left and right. After adopting this structure, the sliding seat can be reliably slidably connected to the base under the action of the guide rail assemblies.
[0028] The first clamping assembly includes two left-right symmetrical first clamping blocks 61 and two left-right symmetrical first adjustment units; the two first clamping blocks 61 are slidably connected to the base 1 and can move closer to or farther away from each other, and a clamping groove 611 is provided on the top of the inner side of each first clamping block 61. The two clamping grooves 611 are used to support and clamp the two corners at one end of the PCBA board 3; the two first adjustment units are both connected to the base 1, and the two first clamping blocks 61 are respectively connected to one of the first adjustment units in a transmission manner. Each first adjustment unit is used to drive the corresponding first clamping block 61 to move relative to the base 1 so that the two first clamping blocks 61 are close to each other. Or away from; by adopting this first clamping assembly, the clamping groove on each first clamping block has two side walls in a vertical state. When the two clamping grooves support and clamp the two corners at one end of the PCBA board, the two side walls of each clamping groove can abut against the two side edges of the corresponding corner of the PCBA board and limit them horizontally. When the two first adjustment units drive the two first clamping blocks to approach each other, the clamping grooves on the two first clamping blocks can clamp one end of the PCBA board. When the two first adjustment units drive the two first clamping blocks to move away from each other, the two first clamping blocks can release the clamping of one end of the PCBA board.
[0029] The lower end of each first clamping block 61 is provided with an inverted "T"-shaped first slider 612, and the base 1 is provided with an inverted "T"-shaped slide groove 11 corresponding to the first slider 612 one by one, and each first slider 612 is slidably fitted in the slide groove 11 on the corresponding side; by adopting this structure, under the cooperation of the inverted "T"-shaped first slider and the inverted "T"-shaped slide groove, each first clamping block can be reliably slidably connected to the base and achieve the purpose of vertical limiting.
[0030] Each first adjustment unit includes a screw support 62 and a first hand screw 63; the two screw supports 62 are symmetrically fixed to the left and right outer walls of the base 1, and the screw parts of the two first hand screws 63 are horizontally inserted into the screw supports 62 on the corresponding side and are threadedly connected to the screw supports 62; a "T"-shaped first clamping portion 631 is provided on the inner end of each first hand screw 63, and a "T"-shaped first clamping groove 613 is provided on the top of the outer side of each first clamping block 61, and each first clamping portion 631 is vertically clamped into the first clamping groove 613 on the corresponding side and is rotatably connected to the first clamping groove 613; by adopting this first adjustment unit, when the first hand screw is tightened, the screw part of the first hand screw is threadedly connected to the base, and the "T"-shaped first clamping portion on the inner end of each first hand screw is rotatably connected to the "T"-shaped first clamping groove on the corresponding first clamping block, thereby conveniently and reliably driving the first clamping block to slide horizontally relative to the base.
[0031] The second clamping assembly includes a connecting seat 71, two left-right symmetrical second clamping blocks 72 and two left-right symmetrical second adjusting units; the connecting seat 71 is fixed on the sliding seat 2, the two second clamping blocks 72 are slidably connected to the connecting seat 71 and can move closer to or away from each other, the upper ends of the two second clamping blocks 72 are used to support the left and right sides of the other end of the PCBA board 3, and the top of the inner side of each second clamping block 72 is provided with a clamping protrusion 721, and the two clamping protrusions 721 are used to engage with the open grooves 31 on both sides of the other end of the PCBA board 3 and clamp the PCBA board 3; the two second adjusting units are both connected to the connecting seat 71, and the two second clamping blocks 72 are respectively engaged with one of the second adjusting units. The segment units are connected in transmission, and each second adjustment unit is used to drive the corresponding second clamping block 72 to move relative to the connecting seat 71 so that the two second clamping blocks 72 are close to or away from each other; after adopting this second clamping assembly, the clamping protrusions on the two second clamping blocks can engage with the open grooves on both sides of the other end of the PCBA board and clamp the PCBA board, and can achieve horizontal limitation of the PCBA board. When the two second adjustment units drive the two second clamping blocks to approach each other, the clamping protrusions on the two second clamping blocks can clamp the other end of the PCBA board. When the two second adjustment units drive the two second clamping blocks to move away from each other, the two second clamping blocks can release the clamping of the other end of the PCBA board.
[0032] A second slider 722 is provided at the lower end of each second clamping block 72, and a sliding hole 711 vertically corresponding to the second slider 722 is provided on the connecting seat 71. Each second slider 722 is vertically penetrated into the sliding hole 711 on the corresponding side and is horizontally slidably connected to the sliding hole 711; after adopting this structure, under the cooperative sliding action of the second slider and the sliding hole, each second clamping block can be reliably horizontally slidably connected to the connecting seat.
[0033] The second clamping assembly also includes a guide rod 73, and a guide hole 723 is provided at the lower end of each second slider 722. The guide rod 73 is inserted into the two guide holes 723, and each second slider 722 is slidably connected to the guide rod 73. Both ends of the guide rod 73 are inserted into the connecting seat 71 and tightly fit with the connecting seat 71; by adopting this structure, under the sliding cooperation of the guide hole and the guide rod, not only can the vertical limiting effect of the second clamping block and the connecting seat be achieved, but also the horizontal sliding of the second slider relative to the connecting seat can be further guided, that is, the reliability of the horizontal sliding connection between the second clamping block and the connecting seat can be further improved.
[0034] The second clamping portion 724 is provided on the top of the outer side of each second clamping block 72, and each second clamping portion 741 is vertically inserted into the second clamping groove 724 on the corresponding side and is rotatably connected to the second clamping groove 724; after adopting this second adjusting unit, when the second hand screw is screwed, the screw portion of the second hand screw is threadedly connected to the connecting seat, and the second clamping portion of the "T" shape on the inner end of each second hand screw is rotatably connected to the second clamping groove on the second clamping block on the corresponding side, thereby conveniently and reliably driving the second clamping block to slide horizontally relative to the connecting seat.
[0035] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.
Claims
1. A universal PCBA board clamping device for high-speed optical modules, characterized by: The invention comprises a base (1), a sliding seat (2), a first clamping assembly and a second clamping assembly; the first clamping assembly is connected to the base (1), the second clamping assembly is connected to the sliding seat (2), the sliding seat (2) and the base (1) are slidably connected so that the second clamping assembly moves closer to or away from the first clamping assembly, a locking structure is provided between the sliding seat (2) and the base (1), and the first clamping assembly and the second clamping assembly are used to support and clamp two opposite ends of a PCBA board (3).
2. The universal PCBA board clamping device for high-speed optical modules according to claim 1, characterized in that: The locking structure comprises two set screws (4) symmetrically threadedly connected to both sides of the sliding seat (2), and the inner end of each set screw (4) is used to abut against the base (1) to lock the sliding seat (2) and the base (1).
3. The universal PCBA board clamping device for high-speed optical modules according to claim 1 or 2, characterized in that: The bottom of the sliding seat (2) is slidably connected to the base (1) via two guide rail assemblies (5) that are arranged symmetrically on the left and right.
4. The universal PCBA board clamping device for high-speed optical modules according to claim 1, characterized in that: The first clamping assembly comprises two left-right symmetrical first clamping blocks (61) and two left-right symmetrical first adjustment units; the two first clamping blocks (61) are both slidably connected to the base (1) and can move closer to or farther away from each other, and a clamping groove (611) is provided on the top of the inner side of each first clamping block (61), and the two clamping grooves (611) are used to support and clamp two corners at one end of the PCBA board (3); the two first adjustment units are both connected to the base (1), and the two first clamping blocks (61) are respectively connected to one of the first adjustment units in a transmission manner, and each first adjustment unit is used to drive the corresponding first clamping block (61) to move relative to the base (1) so that the two first clamping blocks (61) move closer to or farther away from each other.
5. The universal PCBA board clamping device for high-speed optical modules according to claim 4, characterized in that: The lower end of each first clamping block (61) is provided with an inverted "T"-shaped first sliding block (612), and the base (1) is provided with an inverted "T"-shaped sliding groove (11) corresponding to the first sliding block (612) one by one, and each first sliding block (612) is slidably fitted in the sliding groove (11) on the corresponding side.
6. The universal PCBA board clamping device for high-speed optical modules according to claim 4, characterized in that: Each of the first adjustment units comprises a screw support (62) and a first hand-tightening screw (63); the two screw supports (62) are symmetrically fixed on the left and right outer walls of the base (1); the screw rods of the two first hand-tightening screws (63) are horizontally inserted into the screw supports (62) on the corresponding sides and are threadedly connected to the screw supports (62); a first "T"-shaped clamping portion (631) is provided on the inner end portion of each first hand-tightening screw (63); a first "T"-shaped clamping groove (613) is provided on the top of the outer side of each first clamping block (61); each first clamping portion (631) is vertically clamped into the first clamping groove (613) on the corresponding side and is rotatably connected to the first clamping groove (613).
7. The universal PCBA board clamping device for high-speed optical modules according to claim 1, characterized in that: The second clamping assembly includes a connecting seat (71), two second clamping blocks (72) that are symmetrical on both sides, and two second adjustment units that are symmetrical on both sides; the connecting seat (71) is fixed on the sliding seat (2), the two second clamping blocks (72) are slidably connected to the connecting seat (71) and can move closer to or farther away from each other, the upper ends of the two second clamping blocks (72) are used to support the left and right sides of the other end of the PCBA board (3), the top of the inner side of each second clamping block (72) is provided with a clamping protrusion (721), the two clamping protrusions (721) are used to engage with the open grooves (31) on both sides of the other end of the PCBA board (3) and clamp the PCBA board (3); the two second adjustment units are both connected to the connecting seat (71), the two second clamping blocks (72) are respectively connected to one of the second adjustment units in a transmission manner, and each second adjustment unit is used to drive the corresponding second clamping block (72) to move relative to the connecting seat (71) so that the two second clamping blocks (72) move closer to or farther away.
8. The universal PCBA board clamping device for high-speed optical modules according to claim 7, characterized in that: A second sliding block (722) is provided at the lower end of each second clamping block (72), and a sliding hole (711) vertically corresponding to each of the second sliding blocks (722) is provided on the connecting seat (71), and each of the second sliding blocks (722) is vertically inserted into the sliding hole (711) on the corresponding side and is horizontally slidably connected to the sliding hole (711).
9. The universal PCBA board clamping device for high-speed optical modules according to claim 8, characterized in that: The second clamping assembly also includes a guide rod (73), the lower end of each second slider (722) is provided with a guide hole (723), the guide rod (73) is inserted into the two guide holes (723), each second slider (722) is slidably connected to the guide rod (73), and both ends of the guide rod (73) are inserted into the connecting seat (71) and tightly fit with the connecting seat (71).
10. The universal PCBA board clamping device for high-speed optical modules according to claim 7, characterized in that: Each second adjustment unit includes a second hand screw (74); the screw rods of the two second hand screws (74) are horizontally inserted into the left and right ends of the connecting seat (71) and are threadedly connected to the connecting seat (71); a "T"-shaped second clamping portion (741) is provided on the inner end of each second hand screw (74); a "T"-shaped second clamping groove (724) is provided on the top of the outer side of each second clamping block (72); each second clamping portion (741) is vertically clamped into the second clamping groove (724) on the corresponding side and is rotatably connected to the second clamping groove (724).