Welding fixture limiting structure and welding fixture

Abstract

The invention relates to the technical field of automobile manufacturing, and discloses a welding fixture limiting structure and a welding fixture. The welding fixture limiting structure comprises a pressing arm limiting block, a connecting plate limiting block and a connecting plate limiting block adjusting block; the lower end face of the pressing arm limiting block and the upper end face of the connecting plate limiting block can be mutually coupled in the Y direction through a concave-convex groove structure, and the middle portions of the coupling faces of the pressing arm limiting block and the connecting plate limiting block in the length direction can be mutually limited and coupled in the X direction. The front side wall of the connecting plate limiting block is connected with the upper end of one side wall of the aligned connecting plate limiting block adjusting block in an X-direction adjustable displacement manner; according to the abrasion condition of the hinge connecting plate, the positioning structure can be finely adjusted, so that the positioning pin is always located at the original position, the positioning accuracy is ensured, and the situation that the positioning pin bears large tension or the positioning precision loss due to abrasion of the hinge connecting position and positioning deviation is relieved.

Description

Technical Field

[0001] This invention relates to the field of automobile manufacturing technology, and in particular to a welding fixture limiting structure and a welding fixture. Background Technology

[0002] The primary function of welding fixtures is to ensure the stability and positioning accuracy of the parts being welded during the welding process, to avoid welding defects caused by the movement or misalignment of the workpieces, to guarantee the relative positional accuracy of the parts, and to ensure the welding quality of the parts. They are important tooling in the automotive body welding production process.

[0003] See Figure 1 As shown, the welding fixture typically consists of base 1', base 2', support and clamping unit 3', and control unit. The clamping and support unit is used for part positioning, clamping, and fixing, and consists of connecting base 31', cylinder 32', pressure arm 33', positioning pin 34', positioning surface 35', limit block 36', and hinge connecting plate 37'. The limit block structure commonly uses H-type limit block combination structure, V-type limit block combination structure, or cylindrical limit block combination structure. The limit block determines the positional accuracy of the pressure arm, which in turn affects the forming accuracy of the welded parts. Cylindrical limit blocks are often used in conjunction with double guide rod cylinders, while H-type and V-type limit blocks are often used in pressure arm flipping structures.

[0004] Due to repeated rotation and opening / closing of the clamping support unit, the hinge connecting plate is severely worn, the positioning accuracy of the pressure arm decreases, the positioning pin bears a large tensile force, or the pin shaft wears after long-term use of the pressure arm flipping structure, resulting in a loss of positioning accuracy and causing welding deviations. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a welding fixture limiting structure and a welding fixture. Based on the wear condition of the hinge connecting plate, the positioning structure can be finely adjusted to ensure that the positioning pin is always in its original position, guaranteeing positioning accuracy and mitigating the impact of wear at the hinge connection point on positioning deviations, which could cause the positioning pin to bear excessive tension or lose positioning accuracy.

[0006] This invention proposes a welding fixture limiting structure, including a pressure arm limiting block, a connecting plate limiting block, and a connecting plate limiting block adjustment block;

[0007] The lower end face of the pressure arm limiting block and the upper end face of the connecting plate limiting block can be coupled to each other in the Y direction (Y direction is the width direction of the pressure arm limiting block) with a concave-convex groove structure. The concave-convex groove structure coupling is to limit the pressure arm fixed above the pressure arm limiting block and the connecting plate fixed below the connecting plate limiting block in the Y direction. The middle part of the coupling surface of the pressure arm limiting block and the connecting plate limiting block in the length direction can be coupled to each other in the X direction (X direction is the length direction of the pressure arm limiting block). The middle part of the coupling surface of the pressure arm limiting block and the connecting plate limiting block in the length direction can be provided with a concave-convex body protrusion and a body groove to limit the pressure arm limiting block and the connecting plate limiting block in the X direction.

[0008] The front side wall of the connecting plate limiting block is connected to the upper end of one side wall of the adjusting block of the corresponding connecting plate limiting block in an adjustable displacement manner in the X direction. The design purpose is to prevent the pressure arm from shifting forward or backward in the X direction due to repeated rotation and wear of the hinge plate and hinge shaft between the connecting plate and the pressure arm. In this case, the positioning pin will shift relative to the adjusting block of the connecting plate limiting block in the X direction at its initial distance. Inaccurate positioning of the positioning pin will cause it to bear a large tensile force when it contacts the positioning part of the workpiece to be positioned, and the workpiece will be mispositioned, leading to subsequent workpiece welding... If a deviation occurs, keep the fixed position of the connecting plate limit block adjustment block and the front end face of the connecting plate unchanged. Adjust the positioning pin on the pressure arm to the initial distance in the X direction from the connecting plate limit block adjustment block. Then, according to the adjustment amount of the pressure arm, adjust the X-direction displacement of the connecting plate limit block relative to the connecting plate limit block adjustment block and screw the connecting plate limit block adjustment block and the connecting plate back into place. This ensures that after the pressure arm rotates and falls, the initial X-direction distance between the positioning pin and the connecting plate limit block adjustment block remains unchanged, thus ensuring the accurate positioning of the positioning pin on the pressure arm.

[0009] The lower end face of the pressure arm limiting block is provided with a coupling rectangular groove along its length. At least two pressure arm engagement stepped holes are provided along the length of the coupling rectangular groove. The pressure arm limiting block can be screwed and fixed to the pressure arm in the XYZ three directions by bolts passing through the pressure arm engagement stepped holes. The upper end face of the connecting plate limiting block is provided with a coupling rectangular protrusion corresponding to the position of the coupling rectangular groove. The coupling rectangular groove and the coupling rectangular protrusion can be matched and engaged, so that the pressure arm limiting block and the connecting plate limiting block make contact in the Y direction. The coupling rectangular groove and the coupling rectangular protrusion cooperate to achieve Y-direction limiting of the pressure arm and the connecting plate. The coupling rectangular protrusion is provided with... The connecting plate has a stepped hole for screwing in, and the coupling rectangular protrusion is fixed to the connecting plate in the Z-direction by bolts passing through the stepped hole for screwing in; the coupling rectangular groove of the pressure arm limiting block has an X-direction trapezoidal limiting groove in the middle of at least one side wall of the groove, and the corresponding position of the connecting plate limiting block is provided with an X-direction trapezoidal limiting protrusion. The X-direction trapezoidal limiting groove and the X-direction trapezoidal limiting protrusion can be matched and engaged to limit the X-direction displacement between the pressure arm limiting block and the connecting plate limiting block. The X-direction trapezoidal limiting protrusion is designed as a three-dimensional structure to facilitate the guidance of the pressure arm limiting block and reduce the friction during the coupling process of the pressure arm limiting block and the connecting plate limiting block.

[0010] The coupling rectangular groove of the pressure arm limiting block is provided with an X-direction trapezoidal limiting groove in the middle of the side wall of the groove on both sides, and the corresponding position of the connecting plate limiting block is provided with an X-direction trapezoidal limiting protrusion.

[0011] The front side wall of the connecting plate limiting block is provided with an internal thread blind hole. The upper side wall of the connecting plate limiting block adjusting block is provided with an adjusting bolt stepped hole corresponding to the position of the internal thread blind hole. An adjusting bolt passes through the adjusting bolt stepped hole and is threaded into the internal thread blind hole, forming an X-direction adjustable displacement connection. By rotating the adjusting bolt to adjust the depth in the internal thread blind hole, the displacement of the connecting plate limiting block relative to the connecting plate limiting block adjusting block in the X direction can be adjusted. This ensures that the positioning pin on the pressure arm remains unchanged after being rotated and pressed down by the X-direction coupling limiting block, thus ensuring that the positioning accuracy is not affected by wear between the hinge plate and the hinge shaft, which could lead to inaccurate X-direction positioning.

[0012] The coupling rectangular groove and the coupling rectangular protrusion are matched with interlocking inverted trapezoidal protrusions and inverted trapezoidal grooves in the middle of their coupling surfaces. The inverted trapezoidal protrusions in the middle of the coupling rectangular groove, and the inverted trapezoidal groove is aligned in the middle of the coupling rectangular protrusion.

[0013] The upper end face of the coupling rectangular protrusion and the left and right vertical sidewalls are connected by a rounded transition to avoid hard interference in the Y direction during the coupling process of the coupling rectangular groove and the coupling rectangular protrusion, thus playing a guiding role.

[0014] The upper end face of the pressure arm limiting block and the lower end face of the connecting plate limiting block are respectively provided with a pressure arm embedding groove and a connecting plate embedding groove at the position corresponding to the coupling rectangular groove. The pressure arm embedding groove and the connecting plate embedding groove further restrict the Y-direction position between the pressure arm limiting block and the pressure arm, and the Y-direction position between the connecting plate limiting block and the connecting plate.

[0015] The connecting plate limiting block adjustment block also includes at least one adjusting shim. The adjusting shim contacts the inner wall of the connecting plate limiting block adjustment block and is fixed to the connecting plate by screws passing through the connecting plate limiting block adjustment block and the adjusting shim. The number of adjusting shims is increased or decreased according to the forward and backward displacement of the pressure arm X, so that the forward and backward displacement of the connecting plate limiting block X is increased or decreased.

[0016] The connecting plate limiting block has a horizontally protruding quadrangular prism slider on its front sidewall. Two rows of insertion holes are arranged parallel to each other along the length of the left, upper, and right sides of the quadrangular prism slider. The two rows of insertion holes on each side are equidistant, and the insertion holes on the left, upper, and right sides are staggered from back to front. A sliding sleeve square hole is provided on the upper sidewall of the connecting plate limiting block adjusting block corresponding to the position of the quadrangular prism slider. The quadrangular prism slider can be slidably fitted into the sliding sleeve square hole, forming an X-axis adjustable displacement connection. The left, upper, and right sides of the upper part of the connecting plate limiting block adjusting block have insertion holes on three sides of the quadrangular prism slider, which are matched with three staggered holes on the three sides. For the pin holes, a pair of pins can be inserted into a pair of aligned and conductive mating holes and a pair of pin holes. When the hinge plate and hinge shaft wear, causing the pressure arm to extend or retract in the X direction, the locating pin on the pressure arm is always kept in the initial position by sliding the quadrangular prism slider backward or forward on the sliding sleeve square hole. Then, a pair of pins are inserted into a pair of conductive pin holes on the left side wall, upper end face, or right side wall of the upper part of the connecting plate limit block adjustment block and the mating holes on the corresponding face of the quadrangular prism slider. The purpose of the staggered mating holes is to allow for fine adjustment of the displacement of the quadrangular prism slider, so that the quadrangular prism slider with any fine adjustment displacement can be limited and fixed by a pair of pins.

[0017] A welding fixture includes a welding fixture limiting structure, a connecting base, a connecting plate, a cylinder, a hinge plate, a pressure arm, and a positioning pin. The upper end of the connecting base is fixedly connected to the lower left end of the connecting plate. The cylinder is rotatably connected to the lower right end of the connecting plate. The front end of the cylinder's telescopic arm is rotatably connected to the end of the pressure arm. A hinge plate is vertically fixedly connected to the pressure arm near the end of the pressure arm. The lower end of the hinge plate is connected to the upper right end of the connecting plate via a hinge shaft. The pressure arm can move in tandem with the cylinder and rotate in both directions around the hinge shaft of the connecting plate to match the corresponding position of the connecting plate for opening and closing. The positioning pin is fixed to the front side wall of the pressure arm, and a limiting block is embedded in the connecting plate. The upper rear end face of the connecting plate is detachably fixed to the upper rear end face of the connecting plate by bolts. The connecting plate limiting block adjustment block is screwed and fixed to the front side wall of the connecting plate below the connecting plate limiting block. The connecting plate limiting block and the corresponding connecting plate limiting block adjustment block are connected in an adjustable displacement manner in the X direction. The lower end face of the pressure arm limiting block matches and limits the coupling with the upper end face of the connecting plate limiting block. The upper end face of the pressure arm limiting block is embedded in the lower end face of the corresponding pressure arm and is fixed to the pressure arm by bolts. The retraction of the cylinder telescopic arm can drive the pressure arm to rotate and open relative to the connecting plate. The extension of the cylinder telescopic arm can drive the pressure arm to rotate so that the pressure arm and the connecting plate close and contact.

[0018] Beneficial effects

[0019] According to the wear condition of the hinge connecting plate, the positioning structure can be finely adjusted to keep the positioning pin in its original position, ensuring positioning accuracy and reducing the large tensile force or loss of positioning accuracy caused by the positioning pin due to the wear at the hinge connection. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure of existing welding fixtures.

[0021] Figure 2 This is a schematic diagram of the overall structure of the welding fixture limiting structure of the present invention.

[0022] Figure 3 This is a front view structural schematic diagram of an embodiment of the pressure arm limiting block of the present invention.

[0023] Figure 4 This is a bottom view structural schematic diagram of an embodiment of the pressure arm limiting block of the present invention.

[0024] Figure 5 This is a top view schematic diagram of an embodiment of the pressure arm limiting block of the present invention.

[0025] Figure 6 This is a schematic diagram of the left side of an embodiment of the pressure arm limiting block of the present invention.

[0026] Figure 7 This is a schematic diagram of the left side of an embodiment of the connecting plate limiting block of the present invention.

[0027] Figure 8 This is a top view schematic diagram of an embodiment of the connecting plate limiting block of the present invention.

[0028] Figure 9 This is a front view structural schematic diagram of another embodiment of the pressure arm limiting block of the present invention.

[0029] Figure 10 This is a bottom view schematic diagram of another embodiment of the pressure arm limiting block of the present invention.

[0030] Figure 11 This is a front view structural schematic diagram of another embodiment of the connecting plate limiting block of the present invention.

[0031] Figure 12 This is a top view of another embodiment of the connecting plate limiting block of the present invention.

[0032] Figure 13 This is a schematic diagram of the left side of another embodiment of the connecting plate limiting block of the present invention.

[0033] Figure 14 This is a front view schematic diagram of another embodiment of the welding fixture limiting structure of the present invention.

[0034] Figure 15 This is a three-dimensional structural schematic diagram of another embodiment of the welding fixture limiting structure of the present invention.

[0035] Figure 16 This is a schematic diagram illustrating the opening and closing working principle of the welding fixture of the present invention.

[0036] In the picture:

[0037] 1' Ground corner; 2' Base; 3' Support clamping unit; 31' Connecting base; 32' Cylinder; 33' Pressure arm; 34' Positioning pin; 35' Positioning surface; 36' Limiting block; 37' Hinge connecting plate;

[0038] 1. Pressure arm limiting block; 11. Coupling rectangular groove; 12. Pressure arm threaded stepped hole; 13. X-direction trapezoidal limiting groove; 14. Pressure arm embedded groove;

[0039] 2. Connecting plate limiting block; 21. Coupling rectangular protrusion; 22. Connecting plate threaded stepped hole; 23. X-direction trapezoidal limiting protrusion; 24. Internal thread blind hole; 25. Connecting plate embedded groove; 26. Quadrilateral prism slider; 27. Insertion hole;

[0040] 3. Connecting plate limiting block and adjusting block; 31. Adjusting bolt stepped hole; 32. Adjusting bolt; 33. Adjusting shim; 34. Sliding sleeve square hole; 35. Pin hole;

[0041] 4. Connect the base;

[0042] 5. Connecting plate;

[0043] 6. Cylinder;

[0044] 7. Hinge plate;

[0045] 8. Pressure arm;

[0046] 9. Positioning pin. Detailed Implementation

[0047] To make the technical problems solved by the present invention, the technical solutions adopted, and the technical effects achieved clearer, the technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention. Furthermore, it should be noted that, for ease of description, only the parts related to the present invention are shown in the accompanying drawings, not all of them.

[0048] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The terms "first position" and "second position" refer to two different positions.

[0049] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections or detachable connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0050] Example 1

[0051] See Figures 2-8 , Figure 14 As shown, a welding fixture limiting structure includes a pressure arm limiting block 1, a connecting plate limiting block 2, and a connecting plate limiting block adjusting block 3.

[0052] The lower end face of the pressure arm limiting block 1 and the upper end face of the connecting plate limiting block 2 can be coupled to each other in the Y direction with a groove structure, and the middle part of the coupling surface of the pressure arm limiting block 1 and the connecting plate limiting block 2 can be mutually limited and coupled in the X direction.

[0053] The front side wall of the connecting plate limiting block 2 is connected to the upper end of one side wall of the aligned connecting plate limiting block adjusting block 3 in an adjustable displacement manner in the X direction.

[0054] The lower end face of the pressure arm limiting block 1 is provided with a coupling rectangular groove 11 along its length, and the coupling rectangular groove 11 is provided with three pressure arm screwing step holes 12 along its length. The upper end face of the connecting plate limiting block 2 is provided with a coupling rectangular protrusion 21 corresponding to the coupling rectangular groove 11. The coupling rectangular groove 11 and the coupling rectangular protrusion 21 can be matched and fastened. The coupling rectangular protrusion 21 is provided with a connecting plate screwing step hole 22. The middle part of the side wall of the coupling rectangular groove 11 of the pressure arm limiting block 1 is provided with an X-direction trapezoidal limiting groove 13. The corresponding position of the connecting plate limiting block 2 is provided with an X-direction trapezoidal limiting protrusion 23. The X-direction trapezoidal limiting groove 13 and the X-direction trapezoidal limiting protrusion 23 can be matched and fastened.

[0055] The front side wall of the connecting plate limiting block 2 is provided with an internal thread blind hole 24. The upper side wall of the connecting plate limiting block adjusting block 3 is provided with an adjusting bolt step hole 31 corresponding to the internal thread blind hole 24. An adjusting bolt 32 passes through the adjusting bolt step hole 31 and is threaded into the internal thread blind hole 24, forming an X-direction adjustable displacement connection.

[0056] The upper end face of the coupled rectangular protrusion 21 and the left and right vertical sidewalls are connected by a circular arc transition.

[0057] The upper end face of the pressure arm limiting block 1 and the lower end face of the connecting plate limiting block 2 are respectively provided with a pressure arm embedding groove 14 and a connecting plate embedding groove 25 corresponding to the position of the coupling rectangular groove 11.

[0058] Example 2

[0059] See Figures 9-15 As shown, a welding fixture limiting structure differs from Embodiment 1 in that an X-direction trapezoidal limiting groove 13 is provided in the middle of the side wall of the coupling rectangular groove 11 on both sides of the pressure arm limiting block 1, and an X-direction trapezoidal limiting protrusion 23 is provided at the corresponding position of the connecting plate limiting block 2.

[0060] The connecting plate limiting block adjustment block 3 also includes four adjusting shims 33. The adjusting shims 33 are in contact with the inner side wall of the connecting plate limiting block adjustment block 3 and are fixed to the connecting plate by screws passing through the connecting plate limiting block adjustment block 3 and the adjusting shims 33.

[0061] The front sidewall of the connecting plate limiting block 2 is horizontally provided with a quadrangular prism slider 26. The left sidewall, upper end face and right sidewall of the quadrangular prism slider 26 are all arranged in parallel with two rows of insertion holes 27 in the length direction. The two rows of insertion holes 27 on each face are equidistant from each other, and the insertion holes 27 on the left sidewall, upper end face and right sidewall are staggered from back to front. The upper sidewall of the connecting plate limiting block adjusting block 3 is provided with a sliding sleeve square hole 34 corresponding to the position of the quadrangular prism slider 26. The quadrangular prism slider 26 can be limited and slidably sleeved in the sliding sleeve square hole 34 to form an X-direction adjustable displacement connection. The left sidewall, upper end face and right sidewall of the upper part of the connecting plate limiting block adjusting block 3 are provided with three pairs of staggered pin holes 35 corresponding to the insertion holes 27 on the three sides of the quadrangular prism slider 26. A pair of pins can be inserted into a pair of aligned and conductive insertion holes 27 and a pair of pin holes 35.

[0062] Example 3

[0063] A welding fixture limiting structure differs from Embodiments 1 and 2 in that the coupling rectangular groove 11 and the coupling rectangular protrusion 21 are matched with interlocking inverted trapezoidal protrusions and inverted trapezoidal grooves in the middle of their coupling surfaces. The inverted trapezoidal protrusions protruding from the middle of the coupling rectangular groove 11, and the inverted trapezoidal groove is aligned with the middle of the coupling rectangular protrusion 21. The side walls of the coupling rectangular groove 11 on both sides of the pressure arm limiting block 1 do not have X-direction trapezoidal limiting grooves 13.

[0064] Example 4

[0065] See Figure 16 As shown, a welding fixture includes a welding fixture limiting structure, a connecting base 4, a connecting plate 5, a cylinder 6, a hinge plate 7, a pressure arm 8, and a positioning pin 9. The upper end of the connecting base 4 is fixedly connected to the lower left end of the connecting plate 5. The cylinder 6 is rotatably connected to the lower right end of the connecting plate 5. The front end of the telescopic arm of the cylinder 6 is rotatably connected to the end of the pressure arm 8. The hinge plate 7 is vertically fixedly connected to the pressure arm 8 near the end of the pressure arm 8. The lower end hinge pin of the hinge plate 7 is connected to the upper right end of the connecting plate 5. The pressure arm 8 can move in conjunction with the cylinder 6 and rotate in both directions around the hinge pin of the connecting plate 5 via the hinge plate 7, thus aligning with the connecting plate 5. The position should match the opening and closing. The positioning pin 9 is fixed on the front side wall of the pressure arm 8. The connecting plate limiting block 2 is embedded in the upper rear end face of the connecting plate 5 and is detachably fixed to the upper rear end face of the connecting plate 5 by bolts. The connecting plate limiting block adjusting block 3 is screwed and fixed to the front side wall of the connecting plate 5 below the connecting plate limiting block 2. The connecting plate limiting block 2 and the corresponding connecting plate limiting block adjusting block 3 are connected in an adjustable displacement manner in the X direction. The lower end face of the pressure arm limiting block 1 is matched and limited by the upper end face of the connecting plate limiting block 2. The upper end face of the pressure arm limiting block 1 is embedded in the lower end face of the corresponding pressure arm 8 and is screwed and fixed to the pressure arm 8 by bolts.

[0066] Although the invention has been specifically shown and described in conjunction with preferred embodiments, those skilled in the art should understand that various changes in form and detail may be made to the invention without departing from the spirit and scope of the invention as defined in the appended claims, all of which shall be within the scope of protection of the invention.

Claims

1. A welding fixture limiting structure, characterized in that: It includes a pressure arm limiting block (1), a connecting plate limiting block (2), and a connecting plate limiting block adjusting block (3); The lower end face of the pressure arm limiting block (1) and the upper end face of the connecting plate limiting block (2) can be coupled to each other in the Y direction with a groove structure, and the middle part of the coupling surface of the pressure arm limiting block (1) and the connecting plate limiting block (2) can be mutually limited and coupled in the X direction. The connecting plate limiting block (2) connects the front side wall to the corresponding connecting plate limiting block adjustment block (3) the upper end of one side wall is connected in an adjustable displacement manner in the X direction.

2. The welding fixture limiting structure according to claim 1, characterized in that: The lower end face of the pressure arm limiting block (1) is provided with a coupling rectangular groove (11) along the length direction, and at least two pressure arm screwing step holes (12) are provided along the length direction of the coupling rectangular groove (11); the upper end face of the connecting plate limiting block (2) is provided with a coupling rectangular protrusion (21) corresponding to the coupling rectangular groove (11), and the coupling rectangular groove (11) and the coupling rectangular protrusion (21) can be matched and fastened, and the coupling rectangular protrusion (21) is provided with a connecting plate screwing step hole (22); at least one side wall of the coupling rectangular groove (11) of the pressure arm limiting block (1) is provided with an X-direction trapezoidal limiting groove (13), and the corresponding position of the connecting plate limiting block (2) is provided with an X-direction trapezoidal limiting protrusion (23), and the X-direction trapezoidal limiting groove (13) and the X-direction trapezoidal limiting protrusion (23) can be matched and fastened.

3. The welding fixture limiting structure according to claim 2, characterized in that: The coupling rectangular groove (11) of the pressure arm limiting block (1) has an X-direction trapezoidal limiting groove (13) in the middle of the side wall of the groove on both sides, and the corresponding position of the connecting plate limiting block (2) is provided with an X-direction trapezoidal limiting protrusion (23).

4. The welding fixture limiting structure according to claim 3, characterized in that: The front side wall of the connecting plate limiting block (2) is provided with an internal thread blind hole (24). The upper side wall of the connecting plate limiting block adjusting block (3) is provided with an adjusting bolt step hole (31) corresponding to the internal thread blind hole (24). An adjusting bolt (32) passes through the adjusting bolt step hole (31) and is threaded into the internal thread blind hole (24), forming an X-direction adjustable displacement connection.

5. The welding fixture limiting structure according to claim 2, characterized in that: The coupling rectangular groove (11) and the coupling rectangular protrusion (21) are matched with each other inverted trapezoidal protrusion and inverted trapezoidal groove in the middle of their coupling surfaces. The inverted trapezoidal protrusion protrudes in the middle of the coupling rectangular groove (11), and the inverted trapezoidal groove is aligned in the middle of the coupling rectangular protrusion (21).

6. A welding fixture limiting structure according to claim 4 or 5, characterized in that: The upper end face of the coupled rectangular protrusion (21) and the left and right vertical sidewalls are connected by a circular arc transition.

7. The welding fixture limiting structure according to claim 6, characterized in that: The upper end face of the pressure arm limiting block (1) and the lower end face of the connecting plate limiting block (2) are respectively provided with a pressure arm embedding groove (14) and a connecting plate embedding groove (25) corresponding to the position of the coupling rectangular groove (11).

8. The welding fixture limiting structure according to claim 7, characterized in that: The connecting plate limiting block adjustment block (3) also includes at least one adjustment shim (33). The adjustment shim (33) contacts the lower part of the inner side wall of the connecting plate limiting block adjustment block (3) and is fixed to the connecting plate by screws passing through the connecting plate limiting block adjustment block (3) and the adjustment shim (33).

9. The welding fixture limiting structure according to claim 3, characterized in that: The front side wall of the connecting plate limiting block (2) is horizontally provided with a quadrangular prism slider (26). The left side wall, upper end face and right side wall of the quadrangular prism slider (26) are all arranged with two rows of insertion holes (27) in parallel along their length direction. The two rows of insertion holes (27) on each face are equidistant from each other, and the insertion holes (27) on the left side wall, upper end face and right side wall are staggered from back to front. The upper side wall of the connecting plate limiting block adjusting block (3) is provided with a corresponding quadrangular prism slider (26). There is a sliding sleeve square hole (34), and the quadrangular prism slider (26) can be limited and slidably sleeved in the sliding sleeve square hole (34) to form an X-direction adjustable displacement connection; the left side wall, upper end face and right side wall of the upper part of the connecting plate limit block adjustment block (3) are matched with the three sides of the quadrangular prism slider (26) with the insertion holes (27) of the three sides, and three pairs of pin holes (35) are provided with three sides staggered. A pair of pins can be inserted into a pair of insertion holes (27) and a pair of pin holes (35) that are aligned and connected.

10. A welding fixture, characterized in that: The welding fixture limiting structure includes any one of claims 1-9, and further includes a connecting base (4), a connecting plate (5), a cylinder (6), a hinge plate (7), a pressure arm (8), and a positioning pin (9); the upper end of the connecting base (4) is fixedly connected to the lower left end of the connecting plate (5), the cylinder (6) is rotatably connected to the lower right end of the connecting plate (5), the front end of the telescopic arm of the cylinder (6) is rotatably connected to the end of the pressure arm (8), the pressure arm (8) near the end of the pressure arm (8) is vertically fixedly connected to the hinge plate (7), the lower end hinge shaft of the hinge plate (7) is connected to the upper right end of the connecting plate (5), and the pressure arm (8) can move in conjunction with the cylinder (6) and rotate in both directions around the hinge shaft of the connecting plate (5) via the hinge plate (7). The rotation and connection plate (5) are matched and opened and closed. The positioning pin (9) is fixed on the front side wall of the pressure arm (8). The connection plate limiting block (2) is embedded in the upper rear end face of the connection plate (5) and is detachably fixed to the upper rear end face of the connection plate (5) by bolts. The connection plate limiting block adjusting block (3) is screwed and fixed to the front side wall of the connection plate (5) below the connection plate limiting block (2). The connection plate limiting block (2) and the corresponding connection plate limiting block adjusting block (3) are connected in an adjustable displacement manner in the X direction. The lower end face of the pressure arm limiting block (1) is matched and limited by the upper end face of the connection plate limiting block (2). The upper end face of the pressure arm limiting block (1) is embedded in the lower end face of the corresponding pressure arm (8) and is screwed and fixed to the pressure arm (8) by bolts.

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