A pile driving equipment for foundation pit steel sheet pile construction

Abstract

This application relates to the field of building construction technology and discloses a pile driving equipment for foundation pit steel sheet pile construction. During pile driving, the invention includes a pile driving machine body, a guide ring on one side of the machine body, and a chuck for clamping the steel sheet pile rotatably mounted at the bottom end of the guide ring. It also includes a main hydraulic cylinder fixedly mounted at the bottom of the chuck, a pressing plate fixedly mounted at the telescopic end of the main hydraulic cylinder, and a toothed plate adapted to the pressing plate fixedly mounted at the bottom of the chuck. By sliding the pawl within the straight and inclined sliding grooves, the adjusting plate achieves self-locking and reset during the clamping of the water pipe or auger drill rod sleeve. This eliminates the need for frequent compression and unlocking of the adjusting plate during effective clamping of the steel sheet pile, avoiding tilting or deformation problems during installation. This ensures the steel sheet pile maintains a stable and accurate installation state throughout the pile driving process, improving both pile driving efficiency and quality.

Description

Technical Field

[0001] This application relates to the field of building construction technology, and in particular to a piling equipment for foundation pit steel sheet pile construction. Background Technology

[0002] When the sheet pile is clamped by the chuck of the pile driving machine, the telescopic cylinder drives the pressing plate to press the sheet pile onto the toothed plate. At this time, both sides of the sheet pile are completely in contact with the toothed plate or pressing plate, allowing the pile driving machine to effectively complete the pile driving operation under different foundation conditions. When driving piles on hard foundations, special water jet pile driving or spiral pile driving methods are required to ensure that the pile foundation can successfully penetrate the hard geological layer. These two pile driving methods require welding the outlet end of the water pipe or the bottom end of the spiral drill sleeve to the bottom end of the sheet pile during operation, so that the outlet end of the water pipe or the bottom end of the spiral drill sleeve can move down synchronously with the sheet pile, thereby assisting the pile driving and improving the pile driving efficiency.

[0003] Meanwhile, the presence of the water pipe or auger sleeve prevents the pressure plate in the chuck from fully engaging with the bottom of the sheet pile, affecting clamping force and pile planting efficiency. To address this issue, multiple elastic, retractable sliders are installed on the side of the pressure plate closest to the sheet pile to ensure effective contact and sufficient clamping force. However, these retractable sliders cannot self-lock after clamping the water pipe or auger sleeve, potentially leading to slippage. Furthermore, as the pile planting machine chuck repeatedly operates on the sheet pile—clamping the lower section, releasing the clamp, and moving it upwards—the sliders frequently undergo compression and reset. Over time, this repetitive operation can cause the elastic components of the sliders to lose elasticity due to fatigue, resulting in a failure to reset and ultimately affecting the normal operation of the pile planting system. Summary of the Invention

[0004] This application proposes a sheet pile driving device for foundation pit construction, which can form a corresponding clamping shape according to the clamping requirements. This allows the adjusting plate to achieve self-locking and reset during the clamping process of water pipes or spiral drill rod sleeves. In order to achieve effective clamping of sheet piles, the adjusting plate does not need to be frequently compressed and unlocked, avoiding problems such as tilting and deformation of sheet piles during installation. This ensures that the sheet piles maintain a stable and accurate installation state throughout the pile driving process, improving pile driving efficiency and quality. This solves the problem that when using a pile driving machine to drive sheet piles, the clamping structure in the clamp cannot maintain effective clamping with the sheet pile due to different geological environments, thus affecting the pile driving efficiency and quality.

[0005] To achieve the above objectives, this application adopts the following technical solution: a pile driving device for foundation pit steel sheet pile construction, including a pile driving machine body, a guide ring provided on one side of the pile driving machine body, a chuck for clamping the steel sheet pile rotatably installed at the bottom end of the guide ring, a main hydraulic cylinder fixedly installed at the bottom of the chuck, a pressing plate fixedly installed at the telescopic end of the main hydraulic cylinder, a toothed plate adapted to the pressing plate fixedly installed at the bottom of the chuck, multiple adjusting plates slidably installed on the side of the pressing plate near the toothed plate, two adjusting sliding columns symmetrically rotatably installed on the side of the adjusting plate near the pressing plate, and a pawl adapted to the adjusting sliding column fixedly installed inside the pressing plate. When water jet pile driving or spiral pile driving is required due to different foundation conditions, the pressing plate and adjusting plates are driven by the telescopic end of the main hydraulic cylinder to clamp the steel sheet pile. The multiple adjusting plates are adapted to the shape of the water outlet pipe or spiral drill rod sleeve and are self-locked under the action of the pawl, achieving effective clamping of the steel sheet pile.

[0006] Furthermore, the outer side of the adjusting slide column is provided with a straight slide groove and an oblique slide groove. The first and last ends of the straight slide groove are respectively connected to the first or last end of the adjacent oblique slide groove. The inner bottom wall of the oblique slide groove is provided with multiple locking holes, and the bottom end of the pawl is adapted to the locking holes. The multiple locking holes are arranged in an array along the inner curved surface of the oblique slide groove to cooperate with the pawl to complete the self-locking of the adjusting plate and the adjusting slide column.

[0007] Furthermore, the pressing plate has an adjusting groove on the side near the toothed plate that is slidably connected to the adjusting slide column. The inner wall of the adjusting groove has an installation groove that is adapted to the pawl, which provides space for the pawl to move.

[0008] Furthermore, an elastic element is rotatably mounted at the end of the adjusting slide column near the adjusting slide groove, and the end of the elastic element away from the adjusting slide column is fixedly connected to the inner wall of the adjusting slide groove to assist in the reset of the adjusting plate and the adjusting slide column.

[0009] Furthermore, an installation plate is fixedly installed on the telescopic end of the main hydraulic cylinder, and the side of the installation plate away from the main hydraulic cylinder is fixedly connected to the pressing plate by bolts.

[0010] Furthermore, a fixing plate is fixedly installed at the center of the side of the pressing plate near the toothed plate, and multiple adjusting plates are symmetrically fixedly installed on both sides of the fixing plate.

[0011] Furthermore, multiple auxiliary hydraulic cylinders are fixedly installed inside the end of the pressing plate near the main hydraulic cylinder. A piston rod is slidably connected to the end of the auxiliary hydraulic cylinder near the adjusting plate. The piston rod is fitted inside the elastic element, and the end of the piston rod away from the auxiliary hydraulic cylinder is fixedly connected to the adjusting slide column for pressing the adjusting slide column.

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

[0013] This application provides a sheet pile driving device for foundation pit construction. When using water jet or spiral drilling methods for pile driving, the sliding of the pawl in the straight and inclined sliding grooves enables the adjusting plate to achieve self-locking and reset during the clamping of the water pipe or spiral drill rod sleeve. Furthermore, the hydraulic cylinder and piston rod press the adjusting slide column, thus achieving effective clamping of the sheet pile without frequent compression and unlocking of the adjusting plate. This avoids problems such as tilting and deformation of the sheet pile during installation, ensuring that the sheet pile maintains a stable and accurate installation state throughout the driving process, thereby improving driving efficiency and quality. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort:

[0015] Figure 1 This is a three-dimensional structural diagram of the present invention;

[0016] Figure 2 This is a schematic diagram of the guide ring and clamp of the present invention;

[0017] Figure 3 This is a schematic diagram of the main hydraulic cylinder, pressing plate, and adjusting plate of the present invention;

[0018] Figure 4 This is a schematic diagram of the main cross-sectional structure of the pressing plate of the present invention;

[0019] Figure 5 This is a schematic diagram of the structure of the adjusting plate, adjusting slide column and inclined slide groove of the present invention;

[0020] Figure 6 For the present invention Figure 4 Enlarged structural diagram at point A in the middle.

[0021] In the diagram: 1. Pile driver body; 2. Guide ring; 3. Chuck; 4. Main hydraulic cylinder; 401. Mounting plate; 5. Pressing plate; 6. Toothed plate; 7. Adjusting plate; 701. Fixing plate; 8. Adjusting slide column; 9. Pawl; 10. Straight slide groove; 11. Inclined slide groove; 12. Locking hole; 13. Adjusting slide groove; 14. Mounting groove; 15. Elastic element; 16. Secondary hydraulic cylinder; 17. Piston rod. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Example 1, see Figures 1 to 6 A sheet pile driving device for foundation pit construction includes a pile driving machine body 1. A guide ring 2 is provided on one side of the pile driving machine body 1. A clamp 3 is rotatably installed at the bottom end of the guide ring 2. A main hydraulic cylinder 4 is fixedly installed on one side of the bottom end of the clamp 3. A toothed plate 6 adapted to the main hydraulic cylinder 4 is also fixedly installed at the bottom end of the clamp 3. When driving sheet piles through the pile driving machine body 1, the bottom end of the sheet pile is first placed inside the guide ring 2 by a hoisting device. After the sheet pile is engaged with the adjacent sheet pile, the main hydraulic cylinder 4 presses the sheet pile onto the toothed plate 6. Then, the vertical lifting cylinder on the pile driving machine body 1 drives the guide ring 2, the clamp 3 and the sheet pile to be lowered and transplanted. After the vertical lifting cylinder reaches its maximum stroke, the main hydraulic cylinder 4 releases the clamp on the sheet pile and moves upward with the guide ring 2 and the clamp 3 under the action of the vertical lifting cylinder, and re-clamps and drives the sheet pile.

[0024] Please see Figures 2 to 4 A mounting plate 401 is fixedly installed on the telescopic end of the main hydraulic cylinder 4. A pressing plate 5 is bolted to the side of the mounting plate 401 away from the main hydraulic cylinder 4. Multiple adjusting plates 7 are symmetrically slidably installed on the side of the pressing plate 5 away from the main hydraulic cylinder 4. A fixing plate 701 is fixedly installed at the center of the side of the pressing plate 5 near the toothed plate 6. Two adjusting slide columns 8 are symmetrically rotatably installed on the side of the adjusting plate 7 away from the toothed plate 6. An adjusting groove 13 is opened on the side of the pressing plate 5 near the toothed plate 6, which is slidably connected to the adjusting slide column 8. An elastic element 15 is rotatably installed at the end of the adjusting slide column 8 near the adjusting groove 13. The end of the elastic element 15 away from the adjusting slide column 8 is fixedly connected to the inner wall of the adjusting groove 13. The elastic element 15 is used to support the adjusting plate 7 through the adjusting slide column 8. When using water jet piling or spiral piling, the telescopic end of the main hydraulic cylinder 4 drives the pressing plate 5, the fixing plate 701, and multiple adjusting plates 7 to move. This causes the fixing plate 701 to press against the surface of the water pipe or spiral drill rod sleeve, and the multiple adjusting plates 7 are also compressed according to the actual situation. Under the action of the elastic force of the elastic element 15, the multiple adjusting plates 7 are all in contact with the water pipe, spiral drill rod sleeve, or sheet pile, forming an effective clamping of the sheet pile. This prevents the sheet pile from being unevenly stressed due to incomplete contact when clamped by the main hydraulic cylinder 4, pressing plate 5, and toothed plate 6. As a result, problems such as tilting and deformation of the sheet pile during installation are avoided, ensuring that the sheet pile maintains a stable and accurate installation state throughout the piling process, thus improving piling efficiency and quality.

[0025] After the multiple adjusting plates 7 are fully pressed to their longest stroke, the side of the adjusting plate 7 closest to the toothed plate 6 is on the same horizontal plane as the fixed plate 701. During the pile planting process, whether water jet pile planting or spiral pile planting is used, the water pipe or spiral drill rod sleeve needs to be welded to the central axis of the steel sheet pile so that the auxiliary force on both ends of the steel sheet pile is the same and to prevent the steel sheet pile from tilting or shifting. Therefore, the fixed plate 701 is used to fit against the diameter of the water pipe or spiral drill rod sleeve, so it does not need to be extended or retracted.

[0026] Please see Figures 4 to 6 The outer side of the adjusting slide column 8 is provided with a straight slide groove 10 and an oblique slide groove 11. The first and last ends of the straight slide groove 10 are respectively connected to the first or last end of the adjacent oblique slide groove 11. Multiple locking holes 12 are provided on the inner bottom wall of the oblique slide groove 11, and the multiple locking holes 12 are arranged in an array along the inner curved surface of the oblique slide groove 11. The inner wall of the adjusting slide groove 13 is provided with a mounting groove 14. A pawl 9 that matches the locking hole 12 is fixedly installed inside the mounting groove 14. In the initial state, under the action of the elastic force of the elastic element 15, the pawl 9 is placed close to the adjusting slide column 8 for pressing. One end of the plate 5, and the bottom end of the pawl 9, is positioned at the connection between the straight slide groove 10 and the locking hole 12. When the adjusting plate 7 is pressed and slides towards the pressing plate 5, the adjusting plate 7 drives the adjusting slide column 8 to slide synchronously, thereby causing the bottom end of the pawl 9 to slide into the inclined slide groove 11 and pass through several locking holes 12. When the adjusting plate 7 cannot slide, it engages with the corresponding locking hole 12, thereby locking the position of the adjusting plate 7 through the adjusting slide column 8. This allows multiple adjusting plates 7 to form a shape that matches the water pipe or auger drill rod sleeve, effectively clamping the steel sheet pile. This ensures that during water jet pile planting or spiral pile planting, the multiple adjusting plates 7 and elastic elements 15 are not frequently compressed and reset, thus preventing plastic deformation and cracks in the elastic elements 15 due to frequent compression and reset, which would affect their service life. Furthermore, the fitted shape formed by the multiple adjusting plates 7 can limit and guide the water pipe during the pile planting process, preventing the water pipe from tilting and affecting the water pressure. This ensures the quality of the auxiliary pile planting process of the water jet within the pile planting machine body 1. After the current sheet pile is planted, the main hydraulic cylinder 4... The telescopic end drives the pressing plate 5 and adjusting plate 7 to move towards the toothed plate 6 until all the elastic elements 15 are fully compressed. At this time, the pawl 9 gradually slides inside the inclined slide groove 11 to the end of the inclined slide groove 11 near the toothed plate 6 and the connection with the straight slide groove 10, and is no longer engaged with the locking hole 12. Then, the main hydraulic cylinder 4 drives the pressing plate 5 to slide in the opposite direction. Under the action of the elastic force of the elastic element 15, the adjusting plate 7 and adjusting slide column 8 slide towards the toothed plate 6, and the pawl 9 also slides and resets inside the straight slide groove 10 to prepare for the next steel sheet pile to be planted.

[0027] Because the pawl 9 has a certain elasticity when sliding through multiple keyholes 12, so that the bottom end of the pawl 9 can slide out of the current keyhole 12 and into the next keyhole 12, the depth of the straight slide groove 10 is greater than the depth of the oblique slide groove 11, so that the pawl 9 will not get stuck when it slides into the straight slide groove 10 and resets through the straight slide groove 10.

[0028] Example 2, based on Example 1, please refer to... Figure 4 Multiple auxiliary hydraulic cylinders 16 are fixedly installed inside the end of the pressing plate 5 near the main hydraulic cylinder 4, and each auxiliary hydraulic cylinder 16 is adapted to a corresponding adjusting slide column 8. A piston rod 17 is slidably connected to the end of the auxiliary hydraulic cylinder 16 near the adjusting plate 7, and the piston rod 17 is fitted inside the elastic element 15. A piston is fixedly installed at the end of the piston rod 17 near the auxiliary hydraulic cylinder 16, and the piston is slidably installed inside the auxiliary hydraulic cylinder 16. The end of the piston rod 17 away from the auxiliary hydraulic cylinder 16 is fixedly connected to the adjusting slide column 8. In the initial state, the piston rod 17 is completely placed inside the elastic element 15. As the fixing plate 701 presses against the water pipe or auger... After the outer side of the sleeve, each adjusting plate 7 is also compressed. When the adjusting plate 7 slides, it drives the piston rod 17 to slide towards the auxiliary hydraulic cylinder 16. When the adjusting plate 7 can no longer slide under the limiting action of the water pipe or the spiral drill rod sleeve, hydraulic medium is pumped into the rodless chamber of the auxiliary hydraulic cylinder 16 (that is, the inner cavity of the auxiliary hydraulic cylinder 16 near the main hydraulic cylinder 4). This causes the piston rod 17 to press the adjusting slide column 8 under the action of the hydraulic medium, thereby increasing the clamping force of the adjusting plate 7 on the sheet pile. This prevents the adjusting plate 7 from slipping during the sheet pile planting process due to insufficient elasticity of the elastic element 15, and further improves the uniformity of the stress on the sheet pile.

[0029] Working principle:

[0030] When ordinary sheet piles are planted using the main body 1 of the pile driver, a toothed plate 6 is fixedly installed on the mounting plate 401 by a screw. The bottom end of the sheet pile is placed inside the guide ring 2 by the hoisting equipment. After the sheet pile is engaged with the adjacent sheet pile, the extension end of the main hydraulic cylinder 4 drives the mounting plate 401 and the corresponding toothed plate 6 to press the sheet pile onto the toothed plate 6. Then, the vertical lifting cylinder on the main body 1 drives the guide ring 2, the clamp 3 and the sheet pile to be transplanted. After the vertical lifting cylinder reaches its maximum stroke, the main hydraulic cylinder 4 releases the clamp on the sheet pile and moves upward with the guide ring 2 and the clamp 3 under the action of the vertical lifting cylinder to re-clamp and plant the sheet pile.

[0031] When using water jet piling or spiral piling, the mounting plate 401 is fixedly connected to the pressing plate 5 with bolts. In the initial state, under the action of the elastic force of the elastic element 15, the pawl 9 is placed at the end of the adjusting slide column 8 near the pressing plate 5. The extension end of the main hydraulic cylinder 4 drives the pressing plate 5, the fixing plate 701, and multiple adjusting plates 7 to move, so that the fixing plate 701 presses against the surface of the water pipe or spiral drill rod sleeve. When the adjusting plate 7 is squeezed and slides towards the pressing plate 5, the adjusting plate 7 drives the adjusting slide column 8 to slide synchronously, so that the bottom end of the pawl 9 slides into the inclined slide groove 11 and slides through several locking holes 12. When the adjusting plate 7 cannot slide, it is locked into the corresponding locking hole 12, and then the adjusting slide column 8 locks the position of the adjusting plate 7, so that multiple adjusting plates 7 form a shape that is compatible with the water pipe or spiral drill rod sleeve. This forms an effective clamping of the sheet pile, preventing uneven force on the sheet pile due to incomplete contact when clamping it through the main hydraulic cylinder 4, pressing plate 5, and toothed plate 6. This avoids problems such as tilting and deformation of the sheet pile during installation, ensuring that the sheet pile maintains a stable and accurate installation state throughout the planting process, thus improving the efficiency and quality of the planting. Subsequently, hydraulic medium is pumped into the rodless chamber of the auxiliary hydraulic cylinder 16, causing the piston rod 17 to press the adjusting slide column 8 under the action of the hydraulic medium, thereby increasing the clamping force of the adjusting plate 7 on the sheet pile. At the same time, when using water jet planting or spiral planting methods, multiple adjusting plates 7 and elastic elements 15 will not be frequently compressed and reset, thus preventing the elastic elements 15 from plastic deformation and cracks due to frequent compression and reset, which would affect the service life of the elastic elements 15.

[0032] The fitted shape formed by multiple adjusting plates 7 can also limit and guide the water pipe during the pile planting process, preventing the water pipe from tilting and affecting the water pressure, and ensuring the auxiliary pile planting quality level of the water jet during the pile planting process of the pile planting machine body 1. After the current steel sheet pile is planted, hydraulic medium is no longer pumped into the rodless chamber of the auxiliary hydraulic cylinder 16, and the piston rod 17 releases the pressure on the adjusting slide column 8. The extension end of the main hydraulic cylinder 4 drives the pressing plate 5 and adjusting plate 7 to move towards the toothed plate 6 until all the elastic elements 15 are fully compressed. At this time, the pawl 9 gradually slides inside the inclined slide groove 11 to the connection between the inclined slide groove 11 and the straight slide groove 10 near the toothed plate 6, and is no longer locked with the locking hole 12. Then, the main hydraulic cylinder 4 drives the pressing plate 5 to slide in the opposite direction. Under the action of the elastic force of the elastic element 15, the adjusting plate 7 and adjusting slide column 8 slide towards the toothed plate 6, and the pawl 9 also slides and resets inside the straight slide groove 10 to prepare for the next steel sheet pile planting.

[0033] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A pile driving device for foundation pit steel sheet pile construction, comprising a pile driving machine body (1), wherein a guide ring (2) is provided on one side of the pile driving machine body (1), and a clamp (3) for clamping the steel sheet pile is rotatably installed at the bottom end of the guide ring (2), characterized in that, It also includes a main hydraulic cylinder (4) fixedly installed at the bottom of the chuck (3). A pressing plate (5) is fixedly installed at the telescopic end of the main hydraulic cylinder (4). A toothed plate (6) adapted to the pressing plate (5) is also fixedly installed at the bottom of the chuck (3). Multiple adjusting plates (7) are slidably installed on the side of the pressing plate (5) near the toothed plate (6). Two adjusting columns (8) are symmetrically rotated on the side of the adjusting plate (7) near the pressing plate (5). A pawl (9) adapted to the adjusting column (8) is fixedly installed inside the pressing plate (5). An adjusting groove (13) slidably connected to the adjusting column (8) is opened on the side of the pressing plate (5) near the toothed plate (6). An installation groove (14) adapted to the pawl (9) is opened on the inner wall of the adjusting groove (13) to provide the pawl (9) with a space for movement. An elastic element (15) is rotatably installed on the end of the adjusting column (8) near the adjusting groove (13). The end of the elastic element (15) away from the adjusting slide column (8) is fixedly connected to the inner wall of the adjusting slide groove (13) to assist in the reset of the adjusting plate (7) and the adjusting slide column (8). Multiple auxiliary hydraulic cylinders (16) are fixedly installed inside the end of the pressing plate (5) near the main hydraulic cylinder (4). A piston rod (17) is slidably connected to the end of the auxiliary hydraulic cylinder (16) near the adjusting plate (7). The piston rod (17) is fitted inside the elastic element (15), and the piston rod (… 17) The end away from the auxiliary hydraulic cylinder (16) is fixedly connected to the adjusting slide (8) for pressing the adjusting slide (8). When the water jet pile planting method or the spiral pile planting method is required due to different foundation conditions, the pressing plate (5) and the adjusting plate (7) are driven by the telescopic end of the main hydraulic cylinder (4) to clamp the steel sheet pile. The multiple adjusting plates (7) are adapted to the shape of the water outlet pipe or the spiral drill rod sleeve and are self-locked under the action of the pawl (9) to achieve effective clamping of the steel sheet pile.

2. The piling equipment for foundation pit steel sheet pile construction according to claim 1, characterized in that, The outer side of the adjusting slide column (8) is provided with a straight slide groove (10) and an oblique slide groove (11). The first and last ends of the straight slide groove (10) are respectively connected to the first or last end of the adjacent oblique slide groove (11). Multiple locking holes (12) are provided on the inner bottom wall of the oblique slide groove (11), and the bottom end of the pawl (9) is adapted to the locking hole (12). The multiple locking holes (12) are arranged in an array along the inner curved surface direction of the oblique slide groove (11) to cooperate with the pawl (9) to complete the self-locking of the adjusting plate (7) and the adjusting slide column (8).

3. The piling equipment for foundation pit steel sheet pile construction according to claim 1, characterized in that, The telescopic end of the main hydraulic cylinder (4) is fixedly installed with an mounting plate (401), and the side of the mounting plate (401) away from the main hydraulic cylinder (4) is fixedly connected to the pressing plate (5) by bolts.

4. The piling equipment for foundation pit steel sheet pile construction according to claim 1, characterized in that, A fixing plate (701) is fixedly installed at the center of the side of the pressing plate (5) near the toothed plate (6), and multiple adjusting plates (7) are symmetrically fixedly installed on both sides of the fixing plate (701).

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