Plate punching positioning tool

By designing a punching and positioning fixture for sheet metal, laser marking and multi-axis adjustment are used to achieve precise positioning and fine-tuning of large-size sheet metal, solving the problem of cumbersome traditional measurement and positioning, improving processing efficiency and accuracy, and preventing scratches on the sheet metal.

CN224265911UActive Publication Date: 2026-05-22LIAONING ZHONGWANG GROUP CO LTD
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Utility models(China)
Current Assignee / Owner
LIAONING ZHONGWANG GROUP CO LTD
Filing Date
2025-05-26
Publication Date
2026-05-22

AI Technical Summary

Technical Problem

When punching large-sized sheet metal, traditional measurement and positioning methods are cumbersome, resulting in low processing efficiency.

Method used

Design a sheet metal punching and positioning fixture, including a positioning mechanism and a working platform. A laser emitter is used to mark the punching position, and multi-axis adjustment is used to achieve precise positioning and fine adjustment. Combined with a limiting mechanism, the sheet metal is prevented from moving.

Benefits of technology

It significantly improves work efficiency, reduces repetitive measurement steps, enhances positioning accuracy and processing precision, and prevents scratches on the sheet metal.

✦ Generated by Eureka AI based on patent content.

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Abstract

The utility model discloses a plate punching positioning tool, which is used for fixing plates with larger length and width sizes and marking positions to be punched, and comprises a positioning mechanism and a working platform, the positioning mechanism comprises a fixing base, an adjusting screw rod, a vertical sliding base, a transverse sliding base, a first fastening bolt and a laser transmitter. The fixed seat is fixedly arranged on the edge of the working platform, the vertical sliding seat is vertically arranged, the lower end of the vertical sliding seat is arranged on the fixed seat, and a vertical slotted hole is formed in the vertical sliding seat; the transverse sliding seat is provided with a slotted hole formed in the length direction of the transverse sliding seat, a first fastening bolt penetrates through the slotted hole in the transverse sliding seat and the slotted hole in the vertical sliding seat to fixedly connect the transverse sliding seat with the vertical sliding seat, and the laser transmitter is fixedly arranged at one end of the transverse sliding seat. Through the arrangement, the positions, to be punched, of the plates with the large length and width are marked, measurement and marking do not need to be conducted again, and the working efficiency is improved.
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Description

Technical Field

[0001] This utility model relates to the field of aluminum processing technology, specifically to a tooling for positioning holes in sheet metal. Background Technology

[0002] In industrial production, sheet metal, as a crucial basic material, is widely used in numerous industries such as construction, furniture manufacturing, and machining. Punching, as a vital process in sheet metal processing, plays a key role in achieving the functionality and structural stability of the sheet metal. However, for sheets with large dimensions, their size exceeds the processing range of conventional machine tools or punch presses, making direct punching impossible. Currently, when punching such large sheets, operators typically use the following method: first, they measure and locate the position to be punched using a ruler, and then manually punch the hole at the determined location using a drilling tool. This traditional processing method suffers from the technical problem that each sheet requires re-measurement and positioning, making the process cumbersome, time-consuming, and labor-intensive, resulting in low processing efficiency. Utility Model Content

[0003] In view of this, the present invention discloses a punching and positioning fixture for sheet metal, the specific solution of which is as follows:

[0004] A tooling for punching and positioning sheet metal, comprising a positioning mechanism and a working platform;

[0005] The positioning mechanism includes a fixed base, an adjusting screw, a vertical slide, a horizontal slide, a first fastening bolt, and a laser emitter;

[0006] The fixed seat has a C-shaped groove structure in cross section. The edge of the working platform is located inside the fixed seat. A threaded hole is opened on the bottom wall of the fixed seat. The adjusting screw passes through the threaded hole and is screwed to the fixed seat. The upper top wall of the fixed seat and the upper end of the adjusting screw clamp the working platform.

[0007] The vertical slide is arranged vertically, with its lower end set on a fixed base, and a vertical slot is opened on the vertical slide;

[0008] The transverse slide has a slot along its length. The first fastening bolt passes through the slot on both the transverse and vertical slides to fix the transverse and vertical slides together. The laser emitter is fixedly mounted on one end of the transverse slide.

[0009] As a supplement to the technical solution of this utility model, the positioning mechanism further includes a longitudinal slide and a positioning screw. The longitudinal slide is located in the longitudinal direction and is disposed at the upper end of the fixed base. It is provided with a groove along its length.

[0010] The lower end of the vertical slide is provided with a sliding base, which is located in the slide groove of the longitudinal slide. The side wall of the longitudinal slide is provided with a through hole communicating with the slide groove, and the sliding base is provided with a threaded hole. The positioning screw passes through the through hole on the longitudinal slide and is screwed into the threaded hole on the sliding base to fix the sliding base on the longitudinal slide.

[0011] As a supplement to the technical solution of this utility model, the positioning mechanism further includes a positioning pad, a positioning support plate, a second fastening bolt, and a third fastening bolt; the positioning pad is located between the transverse slide and the longitudinal slide, and the positioning pad is provided with a through hole, and the first fastening bolt passes through the transverse slide, the positioning pad, and the vertical slide in sequence to fix the three together.

[0012] The positioning support plate is provided with slots along its length. One end face of the positioning support plate contacts the vertical slide. The second fastening bolt passes through the slots on the positioning support plate and the vertical slide in sequence to fix the two together. The other side face of the positioning support plate contacts the horizontal slide. The third fastening bolt passes through the through holes on the positioning support plate and the horizontal slide in sequence to fix the two together.

[0013] As a supplement to the technical solution of this utility model, the working platform includes legs, a support panel, and baffles. The support panel is disposed on the legs, and the baffles are provided in two sets, namely a longitudinal baffle and a transverse baffle. Both the longitudinal baffle and the transverse baffle are disposed on the support panel. Both the longitudinal panel and the transverse panel are perpendicular to the support panel and are located near the outer edge of the support panel.

[0014] As a supplement to the technical solution of this utility model, the working platform also includes a basic support pad and an adjustable support pad. The basic support pad is provided in two sets and is set on the support panel. One set of basic support pads is set on the side of the horizontal baffle near the center of the support panel, and the other set of basic support pads is set on the side of the horizontal baffle near the center of the support panel.

[0015] The adjustable support pad is disposed on the support panel and at least one set is provided; the support panel is provided with several insertion interfaces, and the bottom of the adjustable support pad is provided with a protrusion for insertion into the insertion interface on the support panel. The support pad is inserted into the insertion interface and fixed on the support panel.

[0016] As a supplement to the technical solution of this utility model, the working platform also includes a limiting mechanism, which includes a limiting slide rail, a limiting slider, and a locking handle;

[0017] The limiting slide rail has a T-shaped cross-section, and the lower part of the limiting slider has a T-shaped groove. The limiting slider is set on the limiting slide rail. The limiting slider has a vertically arranged threaded through hole. The lower part of the locking handle has a screw-like structure. The lower part of the locking handle is screwed into the threaded through hole of the limiting slider, and its lower end can abut against the limiting slide rail.

[0018] The limiting mechanism is provided in at least two sets, one set of which has a limiting slide rail whose length direction is perpendicular to the plane of the transverse baffle, and the other set of which has a limiting slide rail whose length direction is perpendicular to the plane of the longitudinal baffle.

[0019] As a supplement to the technical solution of this utility model, the limiting mechanism also includes a sliding handle, which is disposed on the limiting slider and is used by the operator to push the sliding handle to make the limiting slider slide on the limiting slide rail.

[0020] Beneficial Effects: The plate punching and positioning fixture disclosed in this utility model can significantly improve work efficiency. Punching can proceed only after marking the laser irradiation position, eliminating the need for further measurement and greatly improving efficiency. Simultaneously, the positioning mechanism enables fine-tuning, allowing for position adjustment of the laser emitter in three axes, improving positioning accuracy. In another aspect, the structural design of the work platform effectively fixes the plate, preventing it from shifting or rubbing against the platform and causing scratches. Attached Figure Description

[0021] Figure 1 This is a three-dimensional structural diagram of the present invention.

[0022] Figure 2 This is a schematic diagram of the positioning mechanism of this utility model.

[0023] Figure 3 This is a partial structural diagram of the positioning mechanism of this utility model.

[0024] Figure 4 This is a partial structural diagram of the positioning mechanism of this utility model.

[0025] Figure 5 for Figure 1 Enlarged structural diagram of the structure at point A.

[0026] Figure 6 This is a schematic diagram of the adjustable support pad structure of this utility model.

[0027] In the diagram: 1. Positioning mechanism, 2. Working platform, 3. Fixed seat, 4. Adjusting screw, 5. Vertical slide, 6. Horizontal slide, 7. First fastening bolt, 8. Laser emitter, 9. Longitudinal slide, 10. Positioning screw, 11. Positioning pad, 12. Positioning support plate, 13. Second fastening bolt, 14. Third fastening bolt, 15. Support leg, 16. Support panel, 17. Longitudinal baffle, 18. Horizontal baffle, 19. Basic support pad, 20. Adjustable support pad, 21. Limiting slide rail, 22. Limiting slider, 23. Locking handle, 24. Plug-in interface, 25. Sliding handle, 26. Sliding base. Detailed Implementation

[0028] In the description of this utility model, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0029] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0030] like Figures 1 to 6 As shown, this utility model discloses a plate punching positioning fixture, which is used to achieve precise positioning of the plate to be processed, including a positioning mechanism 1 and a working platform 2.

[0031] The working platform 2 is used to place the sheet material.

[0032] The positioning mechanism 1 includes a fixed base 3, an adjusting screw 4, a vertical slide 5, a horizontal slide 6, a first fastening bolt 7, and a laser emitter 8.

[0033] The fixed seat 3 has a C-shaped groove structure in cross section, with its open end inserted to the edge of the working platform 2. A threaded hole is provided on the bottom wall of the fixed seat 3. The adjusting screw 4 passes through the threaded hole and is screwed to the fixed seat 3, so that the upper end of the adjusting screw 4 is located in the groove of the fixed seat 3. By rotating the adjusting screw 4, the upper top wall of the fixed seat 3 and the upper end of the adjusting screw 4 together clamp the working platform 2, thus fixing the fixed seat 3 on the working platform 2.

[0034] The vertical slide 5 is vertically arranged, corresponding to the Z-axis of the three-dimensional coordinate system, and its lower end is set on the fixed base 3. The vertical slide 5 has a vertical slot.

[0035] The transverse slide 6 has a slot along its length. The first fastening bolt 7 passes through the slots on both the transverse slide 6 and the vertical slide 5, fixing the transverse slide 6 and the vertical slide 5 together. The laser emitter 8 is fixedly connected to one end of the transverse slide 6 by bolts. The transverse slide 6 is used to adjust the relative position of the laser emitter 8 on the X-axis in a three-axis coordinate system.

[0036] With the above setup, when punching and positioning the sheet metal, the sheet metal is first placed on the work platform 2. The operator uses measuring tools to mark the punching position. Then, the positioning mechanism 1 is fixed to the worktable, and the relative position of the horizontal slide 6 on the vertical slide 5 is adjusted so that the laser emitter 8 is positioned above the punching position, ensuring that the laser irradiation position is the same as the punching position. During subsequent sheet metal processing, only the sheet metal needs to be placed on the work platform 2; there is no need to measure the punching position again. Punching can proceed simply by marking the laser irradiation position, significantly improving work efficiency.

[0037] In the above structure, the optimal placement is with the laser emitter 8 directly above the drilling location. The laser irradiation direction is perpendicular to the plane of the material being processed, resulting in the smallest possible spot area and highest precision. When the laser irradiation direction is not perpendicular to the plane of the material, the spot area increases, leading to inaccurate positioning.

[0038] As a preferred embodiment of this utility model, the positioning mechanism 1 further includes a longitudinal slide 9 and a positioning screw 10. The longitudinal slide 9 has its length direction in the longitudinal direction, corresponding to the Y-axis of the three-dimensional coordinate system. The longitudinal slide 9 is disposed on the upper end of the fixed base 3 and has a groove formed along its length direction.

[0039] The lower end of the vertical slide 5 is provided with a sliding base 26, which is located in the groove of the longitudinal slide 9 and can slide along the groove of the longitudinal slide 9. The side wall of the longitudinal slide 9 is provided with a through hole communicating with the groove, and the sliding base 26 is provided with a threaded hole. The positioning screw 10 passes through the through hole on the longitudinal slide 9 and is screwed into the threaded hole on the sliding base 26. When it is necessary to fix the sliding base 26 on the longitudinal slide 9, tighten the positioning screw 10 so that the nut of the positioning screw 10 abuts against the side surface of the longitudinal slide 9.

[0040] With the above settings, when the drilling position needs to be fine-tuned, it is not necessary to disassemble the positioning mechanism 1 from the work platform 2 as a whole. Only the relative position of the vertical slide bar on the Y-axis in the three-dimensional coordinate system and the relative position of the horizontal slide block 6 on the vertical slide block 5 need to be adjusted to adjust the relative position of the laser emitter 8 on the X-axis in the three-dimensional coordinate system, thereby realizing the function of fine-tuning the drilling position.

[0041] In the above structure, when the center of gravity of the transverse slide 6 is far from the first fastening bolt 7, the first fastening bolt 7 is prone to loosening due to the gravity of the transverse slide 6 and the laser emitter 8, causing the position of the positioning laser emitter 8 to shift. As a preferred technical solution of this utility model, the positioning mechanism 1 further includes a positioning pad 11, a positioning support plate 12, a second fastening bolt 13, and a third fastening bolt 14. The positioning pad 11 is located between the transverse slide 6 and the longitudinal slide 9, and has a through hole. The first fastening bolt 7 passes through the transverse slide 6, the positioning pad 11, and the vertical slide 5 in sequence, fixing the three together. The positioning support plate 12 has a slot along its length, and one end face of the positioning support plate 12 contacts the vertical slide 5. The second fastening bolt 13 passes through the slot on the positioning support plate 12 and the vertical slide 5 in sequence, fixing the two together. The other side of the positioning support plate 12 contacts the transverse slide 6. The third fastening bolt 14 passes through the through holes on the positioning support plate 12 and the transverse slide 6 in sequence, fixing the two together. The positioning support plate 12 and the positioning pad 11 have the same thickness. The positioning pad 11 allows the positioning support plate 12 to be fixedly connected to the vertical slide 5 and the transverse slide 6 respectively without bending. The positioning support plate 12 enables the vertical slide 5, the transverse slide 6 and the positioning support plate 12 to form a triangular structure, improving stability and avoiding the technical problem that the first fastening bolt 7 is prone to loosening due to the gravity of the transverse slide 6 and the laser emitter 8 when the center of gravity of the transverse slide 6 is far from the first fastening bolt 7.

[0042] As a preferred embodiment of this utility model, the working platform 2 includes legs 15, a support panel 16, and baffles. The support panel 16 is disposed on the upper end of the legs 15. Two sets of baffles are provided: a longitudinal baffle 17 and a transverse baffle 18. Both the longitudinal baffle 17 and the transverse baffle 18 are disposed on the support panel 16, and both the longitudinal and transverse baffles are perpendicular to the support panel 16. Figure 1 As shown, both the longitudinal panel and the transverse panel are located near the outer edge of the support panel 16. The length direction of the longitudinal panel is parallel to the Y-axis, serving as a limiting plate in the X-axis direction. The length direction of the transverse panel is parallel to the X-axis, serving as a limiting plate in the Y-axis direction, thus enabling preliminary positioning of the material to be processed. The positioning mechanism 1 is clamped at the outer edge of the support panel surface.

[0043] As a preferred embodiment of this invention, the working platform 2 further includes a basic support pad 19 and an adjustable support pad 20. Two sets of the basic support pads 19 are provided, both mounted on the support panel 16. One set of basic support pads 19 is located on the side of the transverse baffle 18 near the center of the support panel 16, and the other set of basic support pads 19 is also located on the side of the transverse baffle 18 near the center of the support panel 16. The length directions of the two sets of basic support pads 19 are longitudinal and transverse, respectively, providing support for the edges of the material to be processed.

[0044] The adjustable support pads 20 are disposed on the support panel 16, and at least one set is provided. The support panel 16 has several insertion interfaces 24. The bottom of each adjustable support pad 20 has a protrusion for insertion into the insertion interfaces 24 on the support panel 16. The support pad is inserted into the insertion interface 24, fixing it to the support panel 16. In use, the basic support pads 19 and the adjustable support pads 20 jointly support the material to be processed. The number of adjustable support pads 20 on the support panel 16 is adjusted according to the size of the material to be processed; the position of the adjustable support pads 20 on the support panel 16 is also adjusted according to the size of the material to be processed and the processing position. During processing, debris falls onto the support panel 16. The placement of the basic support pads 19 and the adjustable support pads 20 prevents direct contact between the material to be processed and the support panel 16, thus preventing scratches. Simultaneously, debris generated during processing can fall through the through holes in the support panel 16 for easy cleaning.

[0045] Preferably, the upper surfaces of the basic support pad 19 and the adjustable support pad 20 are covered with cloth, which can further avoid the technical problem of scratching the plate.

[0046] As a preferred technical solution of this utility model, the above design only uses the longitudinal baffle 17 and the transverse baffle 18 to limit the position of the sheet material to be processed. During the punching process, the position of the sheet material may shift. To solve the above technical problem, the working platform 2 also includes a limiting mechanism. The limiting mechanism includes a limiting slide rail 21, a limiting slider 22, and a locking handle 23.

[0047] The limiting slide rail 21 has a T-shaped cross-section, and the lower part of the limiting slider 22 has a T-shaped groove. The limiting slider 22 is mounted on the limiting slide rail 21 and can slide along the length of the slide rail. The limiting slider 22 has a vertically arranged threaded through hole. The lower part of the locking handle 23 has a screw-like structure. The lower part of the locking handle 23 is screwed into the threaded through hole of the limiting slider 22. As the locking handle 23 is rotated continuously, its lower end can contact the limiting slide rail 21, locking the limiting slider 22 onto the limiting slide rail 21.

[0048] The limiting mechanism is provided in at least two sets. The length direction of the limiting slide rail 21 of one set of limiting mechanism is perpendicular to the plane where the transverse baffle 18 is located, and it is used to clamp the material to be processed with the transverse baffle 18 in the Y-axis direction. The length direction of the limiting slide rail 21 of the other set of limiting mechanism is perpendicular to the plane where the longitudinal baffle 17 is located, and it is used to clamp the material to be processed with the longitudinal baffle 17 in the X-axis direction.

[0049] As a preferred technical solution of this utility model, the limiting mechanism further includes a sliding handle 25, which is disposed on the limiting slider 22 and is used by the operator to push the sliding handle 25 to make the limiting slider 22 slide on the limiting slide rail 21.

[0050] The above description is only a preferred embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be included within the protection scope of the present invention.

Claims

1. A punching and positioning fixture for sheet metal, characterized in that, Includes positioning mechanism (1) and working platform (2); The positioning mechanism (1) includes a fixed seat (3), an adjusting screw (4), a vertical slide (5), a horizontal slide (6), a first fastening bolt (7), and a laser emitter (8); The fixed seat (3) has a C-shaped groove structure in cross section. The edge of the working platform (2) is located inside the fixed seat (3). A threaded hole is provided on the bottom wall of the fixed seat (3). The adjusting screw (4) passes through the threaded hole and is screwed to the fixed seat (3). The upper top wall of the fixed seat (3) and the upper end of the adjusting screw (4) clamp the working platform (2). The vertical slide (5) is arranged vertically, and its lower end is set on the fixed seat (3). The vertical slide (5) has a slot along its length. The transverse slide (6) has a slot along its length. The first fastening bolt (7) passes through the slot on the transverse slide (6) and the vertical slide (5) to fix the transverse slide (6) and the vertical slide (5) together. The laser emitter (8) is fixedly installed at one end of the transverse slide (6) along its length.

2. The sheet metal punching and positioning fixture according to claim 1, characterized in that, The positioning mechanism (1) also includes a longitudinal slide (9) and a positioning screw (10). The longitudinal slide (9) is in the longitudinal direction. The longitudinal slide (9) is located at the upper end of the fixed seat (3) and has a groove opened along its length. The lower end of the vertical slide (5) is provided with a sliding base (26). The sliding base (26) is located in the groove of the longitudinal slide (9). The side wall of the longitudinal slide (9) is provided with a through hole communicating with the groove. The sliding base (26) is provided with a threaded hole. The positioning screw (10) passes through the through hole on the longitudinal slide (9) and is screwed into the threaded hole on the sliding base (26) so that the sliding base (26) is fixed on the longitudinal slide (9).

3. The sheet metal punching and positioning fixture according to claim 2, characterized in that, The positioning mechanism (1) also includes a positioning pad (11), a positioning support plate (12), a second fastening bolt (13), and a third fastening bolt (14); the positioning pad (11) is located between the transverse slide (6) and the longitudinal slide (9), and the positioning pad (11) has a through hole. The first fastening bolt (7) passes through the transverse slide (6), the positioning pad (11), and the vertical slide (5) in sequence to fix the three together. The positioning support plate (12) has slots along its length. One end face of the positioning support plate (12) contacts the vertical slide (5). The second fastening bolt (13) passes through the slots on the positioning support plate (12) and the vertical slide (5) in sequence to fix the two together. The other side of the positioning support plate (12) contacts the horizontal slide (6). The third fastening bolt (14) passes through the through holes on the positioning support plate (12) and the horizontal slide (6) in sequence to fix the two together.

4. The sheet metal punching and positioning fixture according to claim 1, characterized in that, The working platform (2) includes a support leg (15), a support panel (16), and a baffle. The support panel (16) is located on the upper end of the support leg (15). The baffle has two sets, namely a longitudinal baffle (17) and a transverse baffle (18). Both the longitudinal baffle (17) and the transverse baffle (18) are located on the support panel (16). Both the longitudinal panel and the transverse panel are perpendicular to the support panel (16). Both the longitudinal panel and the transverse panel are located near the outer edge of the support panel (16).

5. The sheet metal punching and positioning fixture according to claim 4, characterized in that, The work platform (2) also includes a basic support pad (19) and an adjustable support pad (20). The basic support pad (19) is provided in two sets and is set on the support panel (16). One set of basic support pads (19) is set on the side of the transverse baffle (18) near the center of the support panel (16), and the other set of basic support pads (19) is set on the side of the transverse baffle (18) near the center of the support panel (16). The adjustable support pad (20) is provided on the support panel (16) and at least one set is provided; the support panel (16) is provided with a plurality of insertion interfaces (24), and the bottom of the adjustable support pad (20) is provided with a protrusion for insertion into the insertion interface (24) on the support panel (16). The support pad is inserted into the insertion interface (24) and fixed on the support panel (16).

6. The sheet metal punching and positioning fixture according to claim 5, characterized in that, The work platform (2) also includes a limiting mechanism, which includes a limiting slide rail (21), a limiting slider (22), and a locking handle (23). The limiting slide rail (21) has a T-shaped cross section. The lower part of the limiting slider (22) has a T-shaped groove. The limiting slider (22) is set on the limiting slide rail (21). The limiting slider (22) has a vertically arranged threaded through hole. The lower part of the locking handle (23) has a screw-like structure. The lower part of the locking handle (23) is screwed into the threaded through hole of the limiting slider (22), and its lower end can abut against the limiting slide rail (21). The limiting mechanism is provided in at least two sets. The length direction of the limiting slide rail (21) of one set of limiting mechanism is perpendicular to the plane where the transverse baffle (18) is located, and the length direction of the limiting slide rail (21) of the other set of limiting mechanism is perpendicular to the plane where the longitudinal baffle (17) is located.

7. The sheet metal punching and positioning fixture according to claim 6, characterized in that, The limiting mechanism also includes a sliding handle (25), which is disposed on the limiting slider (22) and is used by the operator to push the sliding handle (25) to make the limiting slider (22) slide on the limiting slide rail (21).