A universal die for angle steel flange welding

Abstract

The present invention provides a universal die for welding angle steel flanges, which relates to the technical field of welding dies, including an angle bracket, a fixed seat and a connecting assembly, wherein the connecting assembly is provided with two and rotatably connected at the center position, two groups of connecting assemblies are rotatably arranged at the center position inside the fixed seat, four angle brackets are provided and respectively hingedly arranged at the end faces of the connecting assembly, and the angle steel flange is placed between the four angle brackets, and sliding seats are respectively provided at the center positions of the four sides of the fixed seat, and telescopic parts are slidably engaged in the sliding seats, and the two ends of the telescopic parts are respectively hingedly arranged with two adjacent connecting assemblies. The present invention extends the connecting assembly by rotating a long gear, and places the end face of each flange strip in two adjacent angle brackets, and then adjusts the angle of the two connecting assemblies according to the length of the flange strips, and shrinks the length of the connecting assembly until the end face of each flange strip fits with the corresponding inner corner of the angle bracket, thereby saving the labor of the staff to splice and limit each corner of the flange strip.

Description

Technical Field

[0001] The invention relates to the technical field of welding moulds, and in particular to a universal mould for angle steel flange welding. Background Art

[0002] Angle steel flange refers to the angle steel or angle iron that is rolled and bent by special equipment. After processing, the two sides of the angle steel are still vertical at 90°, without flanging and wrinkles;

[0003] For example, "CN108581312B" is a universal mold for welding rectangular flanges of angle steels, which relates to the technical field of flange welding molds and aims to solve the problem of inaccurate positioning when there is no fixed mold when welding rectangular flanges of angle steels. The key points of its technical solution are as follows: it includes four groups of upper fixings and lower fixings respectively distributed at the four corners of the rectangular flange, the lower fixings include two lower clamping plates vertically arranged and perpendicular to each other, the two lower clamping plates form an L-shaped structure and are connected by a first connecting member; the upper fixings include two upper clamping plates vertically arranged and perpendicular to each other, the two upper clamping plates form an L-shaped structure and are connected by a second connecting member, and a welding port is provided between the two upper clamping plates and the two lower clamping plates. The present invention utilizes the principle of right angles and the principle of three points determining a plane to accurately position the angle steel;

[0004] However, in the prior art, as shown in the above patent, in the process of assembling and positioning four rectangular angle steel flanges, it is necessary to first align the end faces of two flange strips and fix them through a set of fixed molds to form a stable right angle. Then, the above steps are repeated, and all the corners where the four flange strips are spliced ​​together are equipped with fixed modules to form a rectangle as a whole. In the above process, the operation of positioning the corners of the flange strips using fixed molds needs to be repeated many times, and each set of fixed molds needs to be finely adjusted, and the installation operation is relatively complicated. Summary of the invention

[0005] The purpose of the present invention is to solve the problem in the prior art that the operation of positioning the flange corner using a fixed mold needs to be repeated many times, each set of fixed molds needs to be finely adjusted, and the installation operation is relatively complicated.

[0006] In order to achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a universal mold for welding angle steel flange, comprising an angle bracket, a fixed seat and a connecting assembly, wherein the connecting assembly is provided with two and rotatably connected at the center position, two groups of the connecting assemblies are rotatably arranged at the center position inside the fixed seat, the angle bracket is provided with four and respectively hingedly arranged at the end faces of the connecting assembly, the angle steel flange is placed between the four angle brackets, the center positions of the four sides of the fixed seat are respectively provided with sliding seats, a telescopic member is slidably matched in the sliding seat, and the two ends of the telescopic member are respectively hingedly arranged with two adjacent connecting assemblies, the connecting assembly comprises two tooth plates, a gear assembly is rotatably arranged at the center position of the fixed seat, the two tooth plates are obliquely symmetrical and meshingly arranged on both sides of the gear assembly, a side of the tooth plate close to one end of the fixed seat is provided with side teeth, the end face of the telescopic member is hinged to the end of the tooth plate away from the side teeth, the end of the adjacent tooth plate away from the side teeth is hingedly provided with a telescopic plate, the end of the telescopic plate away from the fixed seat is provided with a pressure plate through a first spring, and an angle block is slidably arranged at the corner position of the angle bracket.

[0007] As a preferred embodiment, a strip groove is provided at the center of the slide seat, and the center of the telescopic member is slidably engaged with the strip groove. The strip groove facilitates the stable sliding of the center of the telescopic member and the slide seat.

[0008] As a preferred embodiment, the telescopic member is arranged in a V-shaped structure, and inner rods are symmetrically slidably provided at both ends of the telescopic member, and one end of the inner rod is hinged to the end face of the connecting component. By arranging the two ends of the telescopic member as a telescopic structure, when one connecting component rotates a certain angle, the other connecting component will also rotate a corresponding angle. By arranging the telescopic member into a V-shaped structure, the telescopic member can be connected to the end face of the connecting component as much as possible when the sliding seat is as short as possible, thereby avoiding obstruction between the telescopic member and the fixed seat when the connecting component rotates a large range.

[0009] As a preferred embodiment, the structures of the ends of the racks on the two connecting components away from the side teeth are the same and are located on the same horizontal line. By arranging the connecting components on the same height line at the outer ends, it is convenient to hinge with the two ends of the telescopic part.

[0010] As a preferred embodiment, the gear assembly includes a sleeve box, a gear ring and a long gear. The gear ring is rotatably arranged at the center position of the sleeve box, and the opposite sides of the two racks are respectively meshed and slid with the outer walls of the gear rings. The two racks are slidably passed through the two ends of the sleeve box, and the two gear rings are rotatably connected up and down. The inner walls of the gear rings are provided with internal teeth, and the long gear is slidably arranged to pass through the two gear rings and mesh with them. When the angles of the two connecting components are adjusted, the long gear is inserted between the two gear rings so that the long gear meshes with the gear rings. When the long gear rotates, it can drive the two gear rings to rotate synchronously, thereby realizing synchronous extension and retraction of the two connecting components. When the angle of the connecting component needs to be adjusted, the two gear rings can be disengaged by pulling out the long gear.

[0011] As a preferred embodiment, an assembly groove is provided at the inner center position of the fixing seat, the lower end of the gear ring below is rotatably connected to the lower part of the assembly groove, the sleeve box is rotatably connected to the assembly groove, and a fan-shaped groove connected to the assembly groove is provided at the corner of the fixing seat. The assembly groove is used for the sleeve box to rotate in the fixing seat, and the fan-shaped groove is used to facilitate the rotation of the connecting component within a certain range of angles.

[0012] As a preferred embodiment, a card slot is provided in the fixed seat above the assembly slot, a connecting shaft is provided at the upper end of the long gear, a snap ring that is slidably adapted to the card slot is provided on the side wall of the connecting shaft, two card slots are provided, the upper end of the connecting shaft passes through the top of the fixed seat and extends outward, a handle is provided at the upper end of the connecting shaft, and the long gear can be slid up and down and switched through the cooperation of the snap ring and the two card slots, which is used to switch the linkage and separation of the two gear rings, and the handle is used to drive the long gear to rotate.

[0013] As a preferred embodiment, the two ends of the telescopic plate are rotatably connected to the upper end surfaces of the adjacent connecting components, a plurality of first springs are evenly arranged between the telescopic plate and the pressure plate, and a telescopic shaft is arranged between the two ends of the telescopic plate and the pressure plate. The plurality of first springs are arranged to limit the extrusion of the flange strip and the angle bracket direction to ensure the stability of the flange strip. The cooperation of the telescopic shaft and the first spring can achieve a more uniform pressure when the pressure plate extrudes the flange strip.

[0014] As a preferred embodiment, a corner groove is provided at the corner of the corner bracket, which is slidably matched with the corner block, a limiting groove is provided on the inner side of the edge of the corner bracket at the corner groove, and a limiting plate is provided on the inner wall of the side edge of the corner block, which is slidably matched with the limiting groove. Through the adaptation of the limiting groove and the limiting plate, the corner block is assembled on the corner bracket to make it stable and the inner wall is flush with the inner wall of the corner bracket.

[0015] As a preferred embodiment, clamping blocks are symmetrically provided at both ends above the corner block, and the clamping blocks are arranged in a U-shaped structure with an open lower end. The clamping blocks are slidably engaged with the upper part of the corner bracket. When the corner block and the corner bracket are slidably assembled, they continue to move downward until the clamping blocks are engaged with the upper part of the corner bracket, thereby achieving stable limiting of the corner bracket and the corner block, and preventing the corner bracket from falling off when the assembly flange is placed.

[0016] Compared with the prior art, the advantages and positive effects of the present invention are:

[0017] 1. The present invention extends the connection assembly by rotating the long gear, and places the end face of each flange strip in two adjacent angle frames, and then adjusts the angle of the two connection assemblies according to the length of the flange strip, and shrinks the length of the connection assembly until the end face of each flange strip fits with the corresponding inner corner of the angle frame. Due to the restrictions of the four-sided flange strips and the four angle frames, the mold has a stable limiting effect on the assembled flange, and then the corner block at the corner of the angle frame is moved upward, exposing the splicing of the end faces of adjacent flange strips to the outside, and the edge staff welds the splicing, which is simple to operate and convenient to use.

[0018] 2. In the process of assembling the flange strip, the rotation angle between the two connecting components can be changed at will, which is suitable for assembling rectangular flanges of different proportions.

[0019] 3. The present invention provides a plurality of first springs for limiting the extrusion direction of the flange strip and the angle bracket to ensure the stability of the flange strip. The cooperation between the telescopic shaft and the first spring can achieve a more uniform pressure when the pressure plate squeezes the flange strip, and the pressure plate has a better limiting effect on the flange strip to prevent it from shifting.

[0020] 4. After the corner block and the corner bracket are slidably assembled, the present invention continues to move downward until the clamping block is engaged with the upper portion of the corner bracket, thereby achieving stable positioning of the corner bracket and the corner block and preventing the corner bracket from falling off during flange assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic diagram of a universal die and flange assembly state for angle steel flange welding provided by the present invention;

[0022] Figure 2 A three-dimensional diagram of a universal die for angle steel flange welding provided by the present invention;

[0023] Figure 3 A schematic diagram of the assembly of a connection component and a gear component of a universal die for angle steel flange welding provided by the present invention;

[0024] Figure 4 A schematic diagram of a universal die for angle steel flange welding provided by the present invention in which a sleeve box and a long gear are separated;

[0025] Figure 5 A schematic diagram of the positions of the long gear and the gear ring of a universal die for angle steel flange welding provided by the present invention;

[0026] Figure 6 A schematic diagram of the internal structure of a fixing seat of a universal die for angle steel flange welding provided by the present invention;

[0027] Figure 7 A schematic diagram of the positions of a telescopic plate and a pressing plate of a universal die for angle steel flange welding provided by the present invention;

[0028] Figure 8 A schematic diagram of the positions of a telescopic plate and a first spring of a universal die for angle steel flange welding provided by the present invention;

[0029] Fig. 9 A schematic diagram of the positions of an angle bracket and an angle block of a universal die for angle steel flange welding provided by the present invention.

[0030] Legend:

[0031] 1. Angle bracket; 2. Fixed seat; 3. Connecting assembly; 4. Sliding seat; 5. Telescopic member; 6. Tooth plate; 7. Telescopic plate; 8. First spring; 9. Pressing plate; 10. Angle block; 11. Strip groove; 12. Inner rod; 131. Box; 132. Gear ring; 133. Long gear; 141. Assembly groove; 142. Fan-shaped groove; 151. Clamping groove; 152. Connecting shaft; 153. Clamping ring; 154. Handle; 16. Telescopic shaft; 171. Angle groove; 172. Limiting groove; 173. Limiting plate; 174. Clamping block. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] See also Figure 1-Figure 9The present invention provides a technical solution: a universal mold for welding angle steel flanges, comprising an angle bracket 1, a fixed seat 2 and a connecting component 3, wherein the connecting component 3 is provided with two and rotatably connected at the center position, two groups of connecting components 3 are rotatably arranged at the center position inside the fixed seat 2, the angle bracket 1 is provided with four end faces of the connecting component 3, respectively hinged, and the angle steel flange is placed between the four angle brackets 1, and a sliding seat 4 is respectively provided at the center position of the four sides of the fixed seat 2, and a telescopic member 5 is slidably matched in the sliding seat 4, and the two ends of the telescopic member 5 are respectively hinged with two adjacent connecting components 3, and the connecting component 3 comprises two tooth plates 6, a gear assembly is rotatably provided at the center position of the fixed seat 2, and the two tooth plates 6 are obliquely symmetrical and mesh with the two sides of the gear assembly slidably arranged, and a side of the tooth plate 6 close to one end of the fixed seat 2 is provided with side teeth, and the end face of the telescopic member 5 is hinged with the end of the tooth plate 6 away from the side teeth, and the end of the adjacent tooth plate 6 away from the side teeth is hinged with a telescopic plate 7, and the end of the telescopic plate 7 away from the fixed seat 2 is provided with a pressing plate 9 through a first spring 8, and an angle block 10 is slidably provided at the corner position of the angle bracket 1.

[0034] like Figure 1-Figure 9 As shown, a strip groove 11 is provided at the center of the slide 4, and the center of the telescopic member 5 is slidably engaged with the strip groove 11. The provided strip groove 11 facilitates the stable sliding of the center of the telescopic member 5 and the slide 4.

[0035] like Figure 1-Figure 9 As shown, the telescopic member 5 is arranged in a V-shaped structure, and the two ends of the telescopic member 5 are symmetrically slidably provided with inner rods 12, and one end of the inner rod 12 is hinged to the end face of the connecting component 3. By arranging the two ends of the telescopic member 5 as a telescopic structure, when one connecting component 3 rotates a certain angle, the other connecting component 3 will also rotate a corresponding angle. By arranging the telescopic member 5 as a V-shaped structure, when the sliding seat 4 is as short as possible, the telescopic member 5 is connected to the end face of the connecting component 3 as much as possible, so as to avoid obstruction between the telescopic member 5 and the fixed seat 2 when the connecting component 3 rotates a large range.

[0036] like Figure 1-Figure 9 As shown, the structures of the ends of the racks on the two connecting components 3 away from the side teeth are the same and are located on the same horizontal line. By arranging the connecting components 3 at the same height line at the outer ends, it is convenient to hinge with the two ends of the telescopic member 5.

[0037] like Figure 1-Figure 9As shown, the gear assembly includes a sleeve 131, a gear ring 132 and a long gear 133. The gear ring 132 is rotatably arranged at the center of the sleeve 131. The opposite sides of the two racks are respectively meshed and slid with the outer wall of the gear ring 132. The two racks are slidably penetrated at both ends of the sleeve 131. The two gear rings 132 are rotatably connected up and down. The inner wall of the gear ring 132 is provided with internal teeth. The long gear 133 is slidably arranged and penetrated in the two gear rings 132 and meshed therewith. When the angles of the two connecting components 3 are adjusted, the long gear 133 is inserted between the two gear rings 132 so that the long gear 133 is meshed with the gear ring 132. When the long gear 133 rotates, the two gear rings 132 can be driven to rotate synchronously, thereby realizing the synchronous extension and retraction of the two connecting components 3. When the angle of the connecting component 3 needs to be adjusted, the two gear rings 132 can be disengaged by pulling out the long gear 133.

[0038] like Figure 1-Figure 9 As shown, an assembly groove 141 is provided at the center position inside the fixing seat 2, the lower end of a gear ring 132 below is rotatably connected to the lower part of the assembly groove 141, the sleeve 131 is rotatably connected to the assembly groove 141, and a fan-shaped groove 142 connected to the assembly groove 141 is provided at the corner of the fixing seat 2. The assembly groove 141 is provided for the sleeve 131 to rotate in the fixing seat 2, and the fan-shaped groove 142 is provided for the connection component 3 to rotate within a certain range of angles.

[0039] like Figure 1-Figure 9 As shown, a slot 151 is provided in the fixing seat 2 above the assembly slot 141, a connecting shaft 152 is provided at the upper end of the long gear 133, a snap ring 153 slidably matched with the slot 151 is provided on the side wall of the connecting shaft 152, two slots 151 are provided, the upper end of the connecting shaft 152 passes through the top of the fixing seat 2 and extends outward, a handle 154 is provided at the upper end of the connecting shaft 152, and the long gear 133 can be slidably switched up and down through the cooperation of the snap ring 153 and the two slots 151, so as to switch the linkage and separation of the two gear rings 132, and the handle 154 is provided to drive the long gear 133 to rotate.

[0040] like Figure 1-Figure 9 As shown, both ends of the telescopic plate 7 are rotatably connected to the upper end surfaces of the adjacent connecting components 3, a plurality of first springs 8 are evenly arranged between the telescopic plate 7 and the pressure plate 9, and a telescopic shaft 16 is arranged between both ends of the telescopic plate 7 and the pressure plate 9. The plurality of first springs 8 are arranged to limit the extrusion direction of the flange strip and the angle bracket 1 to ensure the stability of the flange strip. The cooperation of the telescopic shaft 16 and the first spring 8 can achieve a more uniform pressure when the pressure plate 9 extrudes the flange strip.

[0041] like Figure 1-Figure 9As shown, a corner groove 171 is provided at the corner of the corner frame 1, which is slidably matched with the corner block 10. A limiting groove 172 is provided on the inner side of the edge of the corner frame 1 at the corner groove 171. A limiting plate 173 is provided on the inner wall of the side edge of the corner block 10, which is slidably matched with the limiting groove 172. Through the adaptation of the limiting groove 172 and the limiting plate 173, the corner block 10 is assembled on the corner frame 1 to make it stable and the inner wall is flush with the inner wall of the corner frame 1.

[0042] like Figure 1-Figure 9 As shown, blocks 174 are symmetrically provided at both ends above the corner block 10. The blocks 174 are arranged in a U-shaped structure with an open lower end. The blocks 174 are slidably engaged with the upper portion of the corner frame 1. When the corner block 10 and the corner frame 1 are slidably assembled, they continue to move downward until the blocks 174 are engaged with the upper portion of the corner frame 1. This can achieve stable limiting of the corner frame 1 and the corner block 10, and prevent the corner frame 1 from falling off when the assembly flange is placed.

[0043] Working principle: When using the mold to assemble and limit the rectangular angle steel flange, first select the four flange strips that need to be welded and place them on one side, rotate the gear assembly, drive the tooth plates 6 on the two sets of connecting components 3 to move synchronously in the opposite direction, and increase the overall length of the connecting component 3, so that the flange to be welded can be easily placed in the mold. When placing, place the end face of each flange strip in two adjacent angle frames 1 until all four flange strips are placed. Since the end faces of the flange strips are against the inner wall of the angle frame 1 on both sides, and the end faces of the two spliced ​​flange strips are against each other, the overall corner of the spliced ​​flange is just vertical, and the end faces are flush, and there will be no situation where one end protrudes and the other end is retracted. When placing the flange strip, pull the pressure plate 9 to move toward the telescopic plate 7 to drive the first spring 8 to contract, and place the flange strip between the two The first spring 8 pushes the pressure plate 9 and squeezes the center position of the assembled flange strip, and cooperates with the pressure plate 9 and the two end angle frames 1 to limit the flange strip. The flange strip is stably installed on the mold. During the assembly of the flange strip, the rotation angle between the two connecting components 3 can be changed at will, which is suitable for assembling rectangular flanges of different proportions. Finally, by driving the gear assembly in reverse, the overall length of the two connecting components 3 is shortened synchronously until the end face of each flange strip is fitted with the corresponding inner corner of the angle frame 1. Due to the limitations of the four-sided flange strip and the four angle frames 1, the mold has a stable limiting effect on the assembled flange, and then the corner block 10 at the corner of the angle frame 1 is moved upward, exposing the splicing of the adjacent flange strip end faces, and the edge staff welds the splicing, which is simple to operate and convenient to use.

[0044] The above description is only a preferred embodiment of the present invention and does not limit the present invention in other forms. Any technician familiar with the profession may use the technical content disclosed above to change or modify it into an equivalent embodiment with equivalent changes and apply it to other fields. However, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A universal die for angle steel flange welding, characterized in that: The invention comprises an angle bracket (1), a fixing seat (2) and a connecting assembly (3), wherein the connecting assembly (3) is provided with two and is rotatably connected at the center position, and two groups of the connecting assemblies (3) are rotatably arranged at the center position inside the fixing seat (2) up and down, and the angle bracket (1) is provided with four end faces of the connecting assembly (3) which are respectively hingedly arranged, and angle steel flanges are placed between the four angle brackets (1), and sliding seats (4) are respectively provided at the center positions of the four sides of the fixing seat (2), and a telescopic member (5) is slidably matched in the sliding seat (4), and the two ends of the telescopic member (5) are respectively hingedly arranged with two adjacent connecting assemblies (3), and the The connecting assembly (3) comprises two tooth plates (6), a gear assembly is rotatably provided at the center position of the fixed seat (2), the two tooth plates (6) are obliquely symmetrical and meshingly slidably arranged on both sides of the gear assembly, a side of the tooth plate (6) close to one end of the fixed seat (2) is provided with side teeth, the end face of the telescopic member (5) is hinged to the end of the tooth plate (6) away from the side teeth, a telescopic plate (7) is hinged to the end of the adjacent tooth plate (6) away from the side teeth, a pressure plate (9) is provided at the end of the telescopic plate (7) away from the fixed seat (2) through a first spring (8), and a corner block (10) is provided at the corner position of the corner frame (1) to slide up and down.

2. The universal die for angle steel flange welding according to claim 1, characterized in that: A strip groove (11) is provided at the center of the slide seat (4), and the center of the telescopic member (5) is slidably engaged with the strip groove (11).

3. The universal die for angle steel flange welding according to claim 2, characterized in that: The telescopic member (5) is arranged in a V-shaped structure, and inner rods (12) are symmetrically slidably provided at both ends of the telescopic member (5), and one end of the inner rod (12) is hingedly connected to the end surface of the connecting component (3).

4. The universal die for angle steel flange welding according to claim 1, characterized in that: The gear assembly comprises a sleeve (131), a gear ring (132) and a long gear (133); the gear ring (132) is rotatably arranged at the center of the sleeve (131); opposite sides of the two gear plates (6) are respectively meshed and slid with the outer wall of the gear ring (132); the two gear plates (6) are slidably inserted at both ends of the sleeve (131); the two gear rings (132) are rotatably connected up and down; the inner wall of the gear ring (132) is provided with internal teeth; the long gear (133) is slidably inserted in the two gear rings (132) and meshed with them.

5. The universal die for angle steel flange welding according to claim 4, characterized in that: An assembly groove (141) is provided at the center position inside the fixing seat (2); the lower end of a gear ring (132) below is rotatably connected to the lower part of the assembly groove (141); the sleeve box (131) is rotatably connected to the assembly groove (141); and a fan-shaped groove (142) is provided at a corner of the fixing seat (2) and is connected to the assembly groove (141).

6. The universal die for angle steel flange welding according to claim 5, characterized in that: A clamping groove (151) is provided in the fixing seat (2) above the assembly groove (141); a connecting shaft (152) is provided at the upper end of the long gear (133); a clamping ring (153) slidably matched with the clamping groove (151) is provided on the side wall of the connecting shaft (152); two clamping grooves (151) are provided; the upper end of the connecting shaft (152) passes through the upper part of the fixing seat (2) and extends outside; and a handle (154) is provided at the upper end of the connecting shaft (152).

7. The universal die for angle steel flange welding according to claim 1, characterized in that: The two ends of the telescopic plate (7) are rotatably connected to the upper end surface of the adjacent connecting assembly (3); a plurality of first springs (8) are evenly arranged between the telescopic plate (7) and the pressure plate (9); and a telescopic shaft (16) is arranged between the two ends of the telescopic plate (7) and the pressure plate (9).

8. The universal die for angle steel flange welding according to claim 1, characterized in that: A corner groove (171) is provided at the corner of the corner frame (1) and is slidably matched with the corner block (10); a limiting groove (172) is provided on the inner side of the edge of the corner frame (1) at the corner groove (171); and a limiting plate (173) is provided on the inner side wall of the corner block (10) and is slidably matched with the limiting groove (172).

9. The universal die for angle steel flange welding according to claim 8, characterized in that: Clamping blocks (174) are symmetrically arranged at both ends of the upper side of the corner block (10); the clamping blocks (174) are arranged in a U-shaped structure with an open lower end; and the clamping blocks (174) are slidably matched with the upper side of the corner frame (1).

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