Front triangle welding tool for bicycle frame

Abstract

A bicycle frame front triangle welding tool belongs to the technical field of bicycle frame welding tools and comprises a base, a plurality of L-shaped supports and a U-shaped support, and the L-shaped supports and the U-shaped support are sequentially arranged from front to back and detachably and fixedly connected with the base. Each L-shaped support is provided with a height and angle adjustable positioning mechanism and a corresponding clamping mechanism which are detachably and fixedly connected with the L-shaped support, the U-shaped support is provided with a five-way pipe positioning bracket, a height adjustable vertical pipe positioning seat and a corresponding clamping mechanism from bottom to top, and corresponding frame parts are pressed and fixed after being positioned. The welding tool structure special for the bicycle frame is optimally designed, so that the welding tool structure is matched with bicycle frames of different specifications and models, and the purposes of reducing the auxiliary cost of bicycle production and reducing the management difficulty of a production field are achieved.

Description

Technical Field

[0001] The utility model relates to a welding tool for a bicycle frame, in particular to a welding tool for the front triangle of a bicycle frame. Background Art

[0002] In modern people's lives, bicycles, as a means of green travel, are increasingly loved by people. In order to meet people's different living needs, bicycle manufacturers produce bicycles of different specifications and models, such as adult bicycles, children's bicycles, mountain bikes, road bikes, and so on. The bicycle frame is an important part of a bicycle and is welded from frame parts in a production workshop. In order to ensure the smooth progress of welding operations and welding quality, it is often necessary to use a welding tool to position and clamp the frame parts before welding the bicycle frame. Because there are many specifications and models of bicycles, the bicycle frames are also diverse, with different shapes, sizes, and dimensions. Each type of front triangle of a bicycle frame corresponds to its own dedicated welding tool, which not only results in high auxiliary production costs for bicycles but also leads to difficulties in production site management. Summary of the Utility Model

[0003] The utility model provides a welding tool for the front triangle of a bicycle frame, aiming to optimize the design of the structure of the dedicated welding tool for the front triangle of a bicycle frame so that it can match different specifications and models of bicycle frames, achieving the purpose of reducing the auxiliary production costs of bicycles and the difficulty of production site management.

[0004] To achieve the above object, the utility model adopts the following technical solutions:

[0005] A welding tool for the front triangle of a bicycle frame includes a base and a plurality of L-shaped brackets and a U-shaped bracket that are arranged in sequence from front to back and are detachably and fixedly connected to the base. A positioning mechanism with adjustable height and angle and a corresponding clamping mechanism are provided on each of the plurality of L-shaped brackets and are detachably and fixedly connected thereto. The U-shaped bracket is provided with a five-way pipe positioning bracket, a riser positioning seat with adjustable height, and a corresponding clamping mechanism from bottom to top to position and press and fix the corresponding frame parts after positioning.

[0006] For the above welding tool for the front triangle of a bicycle frame, a plurality of groups of positioning threaded holes are provided on the base, and connection holes adapted to the positioning threaded holes are provided on both the L-shaped brackets and the U-shaped bracket, which are suitable for the fixed connection of the plurality of L-shaped brackets and the U-shaped bracket at each working position.

[0007] The above-mentioned front triangle welding tooling for a bicycle frame. A plurality of the L-shaped brackets include the second L-shaped bracket. A connecting hole one adapted to the positioning threaded hole is provided on the horizontal plane of the second L-shaped bracket. A head tube positioning and clamping device is detachably and fixedly connected to the vertical plane of the second L-shaped bracket. The head tube positioning and clamping device includes a head tube positioning seat, a connecting seat, a sliding seat, and a head tube clamp. A plurality of threaded holes three are provided on the vertical plane of the second L-shaped bracket from bottom to top. A connecting hole adapted to the threaded hole three is provided on the sliding seat to fixedly connect the sliding seat to the second L-shaped bracket. A horizontal sliding pair is provided between the sliding seat and the connecting seat. The mounting base plate of the head tube clamp is fixedly connected to the sliding seat. The telescopic end of the head tube clamp is fixedly connected to the connecting seat. The head tube positioning seat is detachably and fixedly connected to the connecting seat. By operating the head tube clamp, the connecting seat slides back and forth relative to the sliding seat, driving the head tube positioning seat to positionally press or release the head tube. The head tube positioning seat includes an upper positioning block, a lower positioning support block, and a hinged connecting seat. The hinged connecting seat is provided with a hinged ear plate and a mounting vertical plate. The hinged ear plate is provided with a connecting hole two and an arc-shaped slot hole with the connecting hole two as the rotation center. The upper part of the mounting vertical plate is detachably and fixedly connected to the upper positioning block, and a vertical chute two is provided at the lower part. The lower positioning support block is detachably and fixedly connected to the mounting vertical plate through the chute two. The upper positioning block and the lower positioning support block are both provided with positioning slots matching the head tube. A positioning support plate is provided at the bottom of the lower positioning support block, which can position head tubes with different lengths and different angles with respect to the vertical direction.

[0008] In the above-mentioned front triangle welding tooling for a bicycle frame, the head tube clamp is a push-pull type quick clamp.

[0009] The above-mentioned front triangle welding tooling for a bicycle frame. A plurality of the L-shaped brackets include the first L-shaped bracket. A connecting hole one adapted to the positioning threaded hole is provided on the horizontal plane of the first L-shaped bracket. A vertical chute one is provided on the vertical plane of the first L-shaped bracket. The upper and lower tube positioning and clamping mechanism is fixedly connected to the first L-shaped bracket at any height position in the chute one after being rotated to a suitable angle through a rotating connection bolt.

[0010] In the above-mentioned front triangle welding tooling for a bicycle frame, the upper and lower tube positioning and clamping mechanism includes an upper and lower tube positioning bracket and an upper and lower tube clamp. The upper and lower tube positioning bracket includes an upper half seat with an L-shaped cross-section and a lower half seat with a square-shaped cross-section. The two sides of the upper half seat and the adjacent sides of the lower half seat enclose a positioning slot consistent with the upper tube or the lower tube. The upper half seat and the lower half seat slide into the chute one through the rotating connection bolt. The outer side of the lower half seat is fixedly connected to the upper and lower tube clamp, and the upper and lower tube clamp presses and fixes the upper tube or the lower tube in the positioning slot.

[0011] For the above-mentioned front triangle welding tooling of a bicycle frame, the upper and lower tube clamp is a vertical quick clamp.

[0012] For the above-mentioned front triangle welding tooling of a bicycle frame, the U-shaped bracket is sequentially provided with a bottom bracket positioning bracket, a seat tube positioning seat, and a seat tube clamp from bottom to top. The bottom edge of the U-shaped bracket is provided with a first connection hole adapted to the positioning threaded hole. The bottom bracket positioning bracket is fixedly arranged at the center of the bottom edge of the U-shaped bracket. A pair of horizontal clamps are symmetrically arranged from outside to inside at the lower parts of the two side vertical edges of the U-shaped bracket to clamp or loosen the bottom bracket of the bottom bracket positioning bracket. One side vertical edge of the U-shaped bracket extends vertically upward to form a mounting plate. Multiple groups of positioning bolt connection holes are arranged on the mounting plate from bottom to top. The seat tube positioning seat is a split ring structure. The seat tube positioning seat is detachably and fixedly connected to the mounting plate. The pressing head of the seat tube clamp is coaxially arranged with the split ring. The mounting base of the seat tube clamp is detachably and fixedly connected to the mounting plate.

[0013] For the above-mentioned front triangle welding tooling of a bicycle frame, both the horizontal clamp and the seat tube clamp are push-pull type quick clamps.

[0014] For the above-mentioned front triangle welding tooling of a bicycle frame, the first connection hole is an oblong hole.

[0015] For the above-mentioned front triangle welding tooling of a bicycle frame, a base protection cover is arranged on the base. The base protection cover is made of steel plate.

[0016] The present utility model is a front triangle welding tooling for a bicycle frame. By adjusting the front and rear positions of the U-shaped bracket, the first L-shaped bracket, and the second L-shaped bracket on the base, the front and rear direction positioning requirements of the bottom bracket, the seat tube, the upper tube, the lower tube, and the head tube of the front triangle of the bicycle frame with different length dimensions can be met; by adjusting the height position of the seat tube positioning seat on the mounting plate, the vertical direction positioning requirements of the seat tube with different length dimensions can be met; by adjusting the height positions of the upper half seat and the lower half seat in the first sliding groove and the included angle with respect to the vertical plane of the first L-shaped bracket, the positioning requirements of different heights and different inclination angles of the upper tube and the lower tube can be met; by adjusting the angle between the articulated connection seat and the connection seat, the angle direction positioning requirements of the head tube with different rake angles can be met. By adjusting the height position of the lower positioning support block relative to the articulated connection seat and adjusting the height position of the sliding seat relative to the second L-shaped bracket, the height position positioning requirements of the head tube with different heights and length dimensions can be met.

[0017] It can be seen from this that for the present utility model, only by loosening the corresponding bolt connectors can the adjustment of the corresponding positioning mechanism and clamping mechanism be realized to adapt to the assembly positioning of the front triangle parts of bicycle frames with different lengths and different inclination angles, without having to replace the entire front triangle welding tooling for bicycle frames, which improves the versatility of the front triangle welding tooling for bicycle frames and reduces the number of special welding toolings for the front triangles of different models of bicycle frames. Since the types and quantities of welding toolings in bicycle production are reduced, the auxiliary cost of bicycle production is reduced and the difficulty of production site management is lowered, thus solving the problems of high auxiliary cost of bicycle production and great difficulty in production site management. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic structural diagram of the present utility model;

[0019] Figure 2 is Figure 1 a partial enlarged view of area H in

[0020] Figure 3 is Figure 1 a sectional view along the vertical center line of 11-1 (slideway one) in

[0021] Figure 4 is a schematic structural diagram of the articulated connection seat.

[0022] The list of each label in the figure is as follows:

[0023] 1. Base, 1-1. Positioning threaded hole, 2. Bottom bracket tube, 3. Seat tube, 4. Top tube, 5. Down tube, 6. Head tube, 7. U-shaped bracket, 8. Bottom bracket tube positioning bracket, 9. Seat tube positioning seat, 10. Seat tube clamp, 11. L-shaped bracket one, 11-1. Slideway one, 11-2. Bolt connection hole one, 12. Upper and lower tube positioning and clamping mechanism, 12-1. Rotating connection bolt, 12-2. Upper and lower tube positioning bracket, 12-21. Upper half seat, 12-22. Lower half seat, 12-3. Upper and lower tube clamp, 13. L-shaped bracket two, 13-1. Threaded hole three, 14. Head tube positioning and clamping device, 14-1. Head tube positioning seat, 14-1-1. Upper positioning block, 14-1-2. Lower positioning support block, 14-1-21. Positioning support plate, 14-1-3. Articulated connection seat, 14-1-31. Articulated earpiece, 14-1-311. Connection hole two, 14-1-312. Arc-shaped slot hole, 14-1-32. Installation vertical plate, 14-1-321. Slideway two, 14-2. Connection seat, 14-3. Sliding seat, 14-4. Head tube clamp, 15. Horizontal clamp, 16. Base protection cover. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] The present utility model will be further described below in conjunction with the drawings and specific embodiments.

[0025] Referring to FIG. 1, an embodiment of the present utility model provides a front triangle welding tooling for a bicycle frame, which includes a base 1, a plurality of L-shaped brackets and a U-shaped bracket 7 arranged in sequence before and after and detachably and fixedly connected to the base 1. Positioning mechanisms with adjustable height and angle and corresponding clamping mechanisms are provided on each of the plurality of L-shaped brackets and are detachably and fixedly connected thereto. The U-shaped bracket 7 is provided with a bottom bracket positioning bracket 8, a vertically adjustable seat tube positioning seat 9 and corresponding clamping mechanisms from bottom to top, and corresponding frame parts are positioned and then pressed and fixed.

[0026] For the above-mentioned front triangle welding tooling for a bicycle frame, a plurality of groups of positioning threaded holes 1-1 are provided on the base 1, and connection holes adapted to the positioning threaded holes 1-1 are provided on both the L-shaped brackets and the U-shaped bracket 7, which are suitable for the fixed connection of the plurality of L-shaped brackets and the U-shaped bracket 7 at each working position.

[0027] See Figure 1 、 Figure 2 and Figure 4, for the above-mentioned front triangle welding fixture of the bicycle frame, a plurality of the L-shaped brackets include the second L-shaped bracket 13. A first connecting hole 11-2 adapted to the positioning threaded hole 1-1 is provided on the horizontal plane of the second L-shaped bracket 13. A head tube positioning and clamping device 14 is detachably and fixedly connected to the vertical plane of the second L-shaped bracket 13. The head tube positioning and clamping device 14 includes a head tube positioning seat 14-1, a connecting seat 14-2, a sliding seat 14-3, and a head tube clamp 14-4. A plurality of third threaded holes 13-1 are provided on the vertical plane of the second L-shaped bracket 13 from bottom to top. A connecting hole adapted to the third threaded hole 13-1 is provided on the sliding seat 14-3 to fixedly connect the sliding seat 14-3 with the second L-shaped bracket 13. A horizontal sliding pair is provided between the sliding seat 14-3 and the connecting seat 14-2. The mounting base plate of the head tube clamp 14-4 is fixedly connected to the sliding seat 14-3, and the telescopic end of the head tube clamp 14-4 is fixedly connected to the connecting seat 14-2. The head tube positioning seat 14-1 is detachably and fixedly connected to the connecting seat 14-2. By operating the head tube clamp 14-4, the connecting seat 14-2 slides back and forth relative to the sliding seat 14-3, driving the head tube positioning seat 14-1 to position and clamp or release the head tube 6. The head tube positioning seat 14-1 includes an upper positioning block 14-1-1, a lower positioning support block 14-1-2, and a hinged connecting seat 14-1-3. The hinged connecting seat 14-1-3 is provided with a hinged ear plate 14-1-31 and a mounting vertical plate 14-1-32. The hinged ear plate 14-1-31 is provided with a second connecting hole 14-1-311 and an arc-shaped slot hole 14-1-312 with the second connecting hole 14-1-311 as the rotation center. The upper part of the mounting vertical plate 14-1-32 is detachably fixedly connected with the upper positioning block 14-1-1, and a second chute 14-1-321 in the vertical direction is provided at the lower part. The lower positioning support block 14-1-2 is detachably and fixedly connected with the mounting vertical plate 14-1-32 through the second chute 14-1-321. The upper positioning block 14-1-1 and the lower positioning support block 14-1-2 are both provided with positioning slots matching the head tube 6. A positioning support plate 14-1-21 is provided at the bottom of the lower positioning support block 14-1-2, which can position the head tube 6 with different lengths and at different angles with the vertical direction.

[0028] For the above-mentioned front triangle welding fixture of the bicycle frame, the head tube clamp 14-4 is a push-pull type quick clamp.

[0029] See Figure 1 , Figure 3, For the above-mentioned front triangle welding tooling of the bicycle frame, a plurality of the L-shaped brackets include the first L-shaped bracket 11. A connecting hole 11-2 adapted to the positioning threaded hole 1-1 is provided on the horizontal plane of the first L-shaped bracket 11. A vertical chute 11-1 in the vertical direction is provided on the vertical plane of the first L-shaped bracket 11. The upper and lower tube positioning and clamping mechanism 12 is fixedly connected to the first L-shaped bracket 11 after rotating to a suitable angle at any height position in the chute 11-1 through a rotating connecting bolt 12-1; the number of the first L-shaped brackets 11 is configured according to the lengths of the upper tube and the lower tube, and can be one or more.

[0030] , For the above-mentioned front triangle welding tooling of the bicycle frame, the upper and lower tube positioning and clamping mechanism 12 includes an upper and lower tube positioning bracket 12-2 and an upper and lower tube clamp 12-3. The upper and lower tube positioning bracket 12-2 includes an upper half seat 12-21 with an L-shaped cross-section and a lower half seat 12-22 with a square-shaped cross-section. Two sides of the upper half seat 12-21 and adjacent sides of the lower half seat 12-22 form a positioning groove consistent with the upper tube 4 or the lower tube 5. A positioning adjustment screw 12-4 with adjustable height is provided on one side of the upper half seat 12-21 opposite to the pressing head of the upper and lower tube clamp 12-3. The upper half seat 12-21 and the lower half seat 12-22 slide into the chute 11-1 through the rotating connecting bolt 12-1. The outer side of the lower half seat 12-22 is fixedly connected to the upper and lower tube clamp 12-3. After the upper tube 4 and the lower tube 5 are respectively placed in their corresponding positioning grooves and abutted against the positioning adjustment screw 12-4, the upper and lower tube clamp 12-3 is operated to position and then tightly fix the upper tube 4 and the lower tube 5.

[0031] , For the above-mentioned front triangle welding tooling of the bicycle frame, the upper and lower tube clamp 12-3 is a vertical quick clamp.

[0032] See Figure 1 , For the above-mentioned front triangle welding tooling of the bicycle frame, the U-shaped bracket 7 is sequentially provided with a five-way tube positioning bracket 8, a seat tube positioning seat 9, and a seat tube clamp 10 from bottom to top. A connecting hole 11-2 adapted to the positioning threaded hole 1-1 is provided at the bottom of the U-shaped bracket 7. The five-way tube positioning bracket 8 is fixedly arranged at the center of the bottom of the U-shaped bracket 7. A pair of horizontal clamps 15 are symmetrically arranged on the lower parts of the two side vertical edges of the U-shaped bracket 7 from outside to inside to clamp or loosen the five-way tube 2 on the five-way tube positioning bracket 8. An installation plate extends vertically upward from one side vertical edge of the U-shaped bracket 7. Multiple groups of positioning bolt connection holes are arranged on the installation plate from bottom to top. The seat tube positioning seat 9 is a split ring structure. The seat tube positioning seat 9 is detachably fixedly connected to the installation plate. The pressing head of the seat tube clamp 10 is coaxially arranged with the split ring. The installation base of the seat tube clamp 10 is detachably fixedly connected to the installation plate.

[0033] For the above-mentioned front triangle welding tooling for a bicycle frame, both the horizontal clamp 15 and the vertical pipe clamp 10 are push-pull type quick clamps.

[0034] For the above-mentioned front triangle welding tooling for a bicycle frame, the first connecting hole 11-2 is an oblong hole.

[0035] For the above-mentioned front triangle welding tooling for a bicycle frame, a base protection cover 16 is arranged on the base 1, and the base protection cover 16 is made of steel plate.

[0036] In the embodiment of the present utility model, a front triangle welding tooling for a bicycle frame can meet the positioning requirements in the front-back direction of the bottom bracket tube 2, the vertical pipe 3, the upper tube 4, the lower tube 5, and the head tube 6 of the front triangle of a bicycle frame with different length dimensions by adjusting the front-back positions of the U-shaped bracket 7, the first L-shaped bracket 11, and the second L-shaped bracket 13 on the base 1; the positioning requirements in the vertical direction of the vertical pipe 3 with different length dimensions can be met by adjusting the height position of the vertical pipe positioning seat 9 on the mounting plate; the positioning requirements in the angular direction and height direction of the upper tube 4 and the lower tube 5 with different inclination angles in the front triangle of the bicycle frame can be met by adjusting the height positions of the upper half seat 12-21 and the lower half seat 12-22 in the first sliding groove 11-1 and the included angle with respect to the vertical plane of the first L-shaped bracket 11; the positioning requirements in the angular direction of the head tube 6 with different rake angles can be met by adjusting the angle between the articulated connecting seat 14-1-3 and the connecting seat 14-2, and the positioning requirements in the height position of the head tube 6 with different heights and length dimensions can be met by adjusting the height position of the lower positioning support block 14-1-2 relative to the articulated connecting seat 14-1-3 and adjusting the height position of the sliding seat 14-3 relative to the second L-shaped bracket 13; the first connecting hole 11-2 is an oblong hole, which makes it more convenient to align and align the first L-shaped bracket 11, the second L-shaped bracket 13, and the U-shaped bracket 7 during installation, improves the assembly work efficiency of the front triangle welding tooling for the bicycle frame, and reduces the auxiliary cost of bicycle production.

[0037] A base protection cover 16 is arranged on the base 1, which avoids the damage to the base caused by the splash of welding slag during the welding process, reduces the repair, maintenance, and servicing costs of the base, and further reduces the auxiliary cost of bicycle production.

[0038] In summary, in the embodiment of the present utility model, only by loosening the corresponding bolt connectors, the adjustment of the corresponding positioning mechanism and clamping mechanism can be realized to adapt to the assembly positioning of the front triangle parts of bicycle frames with different lengths and angles, without having to replace the entire front triangle welding tooling for bicycle frames, improving the versatility of the front triangle welding tooling for bicycle frames and reducing the number of special welding toolings for the front triangles of different models of bicycle frames. Since the types and quantities of welding toolings in bicycle production are reduced, the auxiliary cost of bicycle production is reduced and the difficulty of production site management is lowered, solving the problems of high auxiliary cost of bicycle production and great difficulty of production site management.

Claims

1. A welding fixture for the front triangle of a bicycle frame, characterized in that It includes a base (1), a plurality of L-shaped brackets and a U-shaped bracket (7) arranged in sequence before and after and detachably and fixedly connected to the base (1). Positioning mechanisms with adjustable height and angle and corresponding clamping mechanisms detachably and fixedly connected thereto are provided on each of the plurality of L-shaped brackets. A five-way pipe positioning bracket (8), a vertically pipe positioning seat (9) with adjustable height and corresponding clamping mechanisms are provided on the U-shaped bracket (7) from bottom to top, and corresponding frame parts are positioned and then pressed and fixed.

2. The front triangle welding tooling for a bicycle frame according to claim 1, characterized in that: Multiple groups of positioning threaded holes (1-1) are provided on the base (1), and connection holes adapted to the positioning threaded holes (1-1) are provided on both the L-shaped brackets and the U-shaped bracket (7), which are suitable for the fixed connection of each of the plurality of L-shaped brackets and the U-shaped bracket (7) at each working position.

3. The front triangle welding tooling for a bicycle frame according to claim 2, characterized in that: The multiple L-shaped brackets include the second L-shaped bracket (13). A first connection hole (11-2) adapted to the positioning threaded hole (1-1) is provided on the horizontal plane of the second L-shaped bracket (13). A head tube positioning and clamping device (14) is detachably and fixedly connected to the vertical plane of the second L-shaped bracket (13). The head tube positioning and clamping device (14) includes a head tube positioning seat (14-1), a connection seat (14-2), a sliding seat (14-3), and a head tube clamp (14-4). Multiple third threaded holes (13-1) are provided on the vertical plane of the second L-shaped bracket (13) from bottom to top. A connection hole adapted to the third threaded hole (13-1) is provided on the sliding seat (14-3) to fixedly connect the sliding seat (14-3) to the second L-shaped bracket (13). A horizontal sliding pair is provided between the sliding seat (14-3) and the connection seat (14-2). The mounting base plate of the head tube clamp (14-4) is fixedly connected to the sliding seat (14-3), and the telescopic end of the head tube clamp (14-4) is fixedly connected to the connection seat (14-2). The head tube positioning seat (14-1) is detachably and fixedly connected to the connection seat (14-2). By operating the head tube clamp (14-4), the connection seat (14-2) slides back and forth relative to the sliding seat (14-3), driving the head tube positioning seat (14-1) to position and clamp or release the head tube (6). The head tube positioning seat (14-1) includes an upper positioning block (14-1-1), a lower positioning support block (14-1-2), and a hinged connection seat (14-1-3). The hinged connection seat (14-1-3) is provided with a hinged ear plate (14-1-31) and a mounting vertical plate (14-1-32). The hinged ear plate (14-1-31) is provided with a second connection hole (14-1-311) and an arc-shaped slot hole (14-1-312) with the second connection hole (14-1-311) as the rotation center. The upper part of the mounting vertical plate (14-1-32) is detachably and fixedly connected to the upper positioning block (14-1-1), and a second chute (14-1-321) in the vertical direction is provided at the lower part. The lower positioning support block (14-1-2) is detachably and fixedly connected to the mounting vertical plate (14-1-32) through the second chute (14-1-321). The upper positioning block (14-1-1) and the lower positioning support block (14-1-2) are both provided with positioning slots matching the head tube (6). A positioning support plate (14-1-21) is provided at the bottom of the lower positioning support block (14-1-2), which can position head tubes (6) with different lengths and different angles with the vertical direction.

4. The front triangle welding tooling for a bicycle frame according to claim 3, characterized in that: The head tube clamp (14-4) is a push-pull type quick clamp.

5. The front triangle welding tooling for a bicycle frame according to claim 3, characterized in that: The multiple L-shaped brackets include the first L-shaped bracket (11). A first connection hole (11-2) adapted to the positioning threaded hole (1-1) is provided on the horizontal plane of the first L-shaped bracket (11). A first chute (11-1) in the vertical direction is provided on the vertical plane of the first L-shaped bracket (11). The upper and lower pipe positioning and clamping mechanism (12) is fixedly connected to the first L-shaped bracket (11) at any height position in the first chute (11-1) after rotating to a suitable angle through a rotating connection bolt (12-1).

6. The front triangle welding tooling for a bicycle frame according to claim 5, characterized in that: The upper and lower pipe positioning and clamping mechanism (12) includes an upper and lower pipe positioning bracket (12-2) and an upper and lower pipe clamp (12-3). The upper and lower pipe positioning bracket (12-2) includes an upper half seat (12-21) with an L-shaped cross section and a lower half seat (12-22) with a rectangular cross section. Two sides of the upper half seat (12-21) and adjacent sides of the lower half seat (12-22) enclose a positioning groove consistent with the upper pipe (4) or the lower pipe (5). The upper half seat (12-21) and the lower half seat (12-22) slide into the first chute (11-1) through the rotating connection bolt (12-1). The outer side of the lower half seat (12-22) is fixedly connected to the upper and lower pipe clamp (12-3). The upper and lower pipe clamp (12-3) presses and fixes the upper pipe (4) or the lower pipe (5) in the positioning groove.

7. The front triangle welding tooling for a bicycle frame according to claim 6, characterized in that: The upper and lower pipe clamp (12-3) is a vertical quick clamp.

8. The front triangle welding tooling for a bicycle frame according to claim 2, characterized in that: The U-shaped bracket (7) is sequentially provided with a five-way pipe positioning bracket (8), a riser pipe positioning seat (9), and a riser pipe clamp (10) from bottom to top. A first connection hole (11-2) adapted to the positioning threaded hole (1-1) is provided at the bottom of the U-shaped bracket (7). The five-way pipe positioning bracket (8) is fixedly arranged at the center of the bottom of the U-shaped bracket (7). A pair of horizontal clamps (15) are symmetrically arranged from outside to inside at the lower parts of the two side vertical edges of the U-shaped bracket (7) to clamp or release the five-way pipe (2) on the five-way pipe positioning bracket (8). An installation plate extends vertically upward from a side vertical edge of the U-shaped bracket (7). Multiple groups of positioning bolt connection holes are provided on the installation plate from bottom to top. The riser pipe positioning seat (9) is a split-ring structure. The riser pipe positioning seat (9) is detachably and fixedly connected to the installation plate. The pressing head of the riser pipe clamp (10) is coaxially arranged with the split-ring. The installation base of the riser pipe clamp (10) is detachably and fixedly connected to the installation plate.

9. The front triangle welding tooling for a bicycle frame according to claim 8, characterized in that: Both the horizontal clamp (15) and the riser pipe clamp (10) are push-pull type quick clamps.

10. The front triangle welding tooling for a bicycle frame according to any one of claims 3, 5, and 8, characterized in that: The first connection hole (11-2) is an oblong hole.

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