A child bicycle frame front triangle component welding tool

Abstract

A child bicycle frame front triangular part welding tool is provided with a base assembly, a front pipe positioning and pressing mechanism, an inclined support pipe positioning and pressing mechanism, a cross support pipe positioning mechanism, a vertical pipe positioning and pressing mechanism and a five-way pipe positioning and pressing mechanism; the base assembly is assembled with a power output end of a welding station positioner, the bottom plate thereof is an L-shaped flat plate, the front pipe positioning and pressing mechanism is installed on the inner side of the long arm of the L-shaped flat plate, a front pipe and an inclined support pipe welding avoidance area is formed between the front pipe positioning and pressing mechanism and the short arm of the L-shaped flat plate, and cross support pipe, vertical pipe, five-way pipe and inclined support pipe welding avoidance areas are arranged on the short arm of the L-shaped flat plate; the inclined support pipe positioning and pressing mechanism, the cross support pipe positioning mechanism, the vertical pipe positioning and pressing mechanism and the five-way pipe positioning and pressing mechanism are installed on the bottom plate and are arranged around the cross support pipe, the vertical pipe, the five-way pipe and the inclined support pipe welding avoidance areas. The child bicycle frame front triangular part welding tool realizes reliable positioning of a welding workpiece, improves welding quality and guarantees the consistency of the overall vehicle assembly size.

Description

Technical Field

[0001] This utility model relates to the field of welding technology, specifically a welding fixture for the front triangle component of a children's bicycle frame. Background Technology

[0002] Children's bicycles are riding tools specially designed for children's physical characteristics. They combine entertainment, exercise, and coordination training. To accommodate children of different ages and heights, children's bicycles come in various models and specifications.

[0003] In the production of children's bicycles, the welding quality of the frame not only affects the bicycle's safety performance but is also a key factor in ensuring the consistency of the overall assembly dimensions. (See attached image) Figure 1 , Figure 2 The diagram shows a front triangle component of a children's bicycle frame. This front triangle component 1 consists of a front tube 1-1, a diagonal brace tube 1-2, a cross brace tube 1-3, a riser tube 1-4, and a bottom bracket tube 1-5. These components are assembled together by welding. The horizontal distance B between the front tube 1-1 and the bottom bracket tube 1-5, and the tilt angle θ of the diagonal brace tube 1-2, are important parameters for inspecting the welding process of the front triangle component 1 and serve as the basis for judging the quality of the welded workpiece. However, because the diagonal brace tube 1-2 is a large-diameter bent tube, and the cross brace tube 1-3 is a structure specifically designed to improve the overall strength of the frame, facilitate the handling of the children's bicycle, and enhance its aesthetic appearance, traditional welding fixtures for the front triangle component of bicycle frames are difficult to match the special structure of this children's bicycle frame. Therefore, an innovative design for the welding fixture of the front triangle component of this children's bicycle frame is required. Utility Model Content

[0004] This utility model provides a welding fixture for the front triangle component of a children's bicycle frame. It aims to achieve reliable positioning of the front triangle component of the children's bicycle frame through the cooperation of the base assembly, the front tube positioning and clamping mechanism, the diagonal brace tube positioning and clamping mechanism, the cross brace tube positioning mechanism, the riser tube positioning and clamping mechanism, and the bottom bracket tube positioning and clamping mechanism, thereby improving the quality of welded products and ensuring the consistency of the overall bicycle assembly dimensions.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A welding fixture for the front triangle component of a children's bicycle frame includes a base assembly, a front tube positioning and clamping mechanism, a diagonal brace tube positioning and clamping mechanism, a cross brace tube positioning mechanism, a riser tube positioning and clamping mechanism, and a bottom bracket tube positioning and clamping mechanism. The base assembly is assembled with the power output end of the welding station positioner. A base plate is set in the base assembly. The base plate is an L-shaped flat plate. A front tube positioning and tightening mechanism is installed on the inner side of the long arm of the L-shaped flat plate. A welding avoidance area between the front tube and the diagonal support tube is formed between the front tube positioning and tightening mechanism and the short arm of the L-shaped flat plate. Welding avoidance areas for the horizontal support tube, vertical tube, five-way tube, and diagonal support tube are set on the short arm of the L-shaped flat plate. The welding avoidance areas for the horizontal support tube, vertical tube, five-way tube, and diagonal support tube are inverted L-shaped avoidance holes. The diagonal brace tube positioning and clamping mechanism is installed on the base plate and includes two parts arranged in front and rear. The front and rear parts extend to the welding avoidance area between the front tube and the diagonal brace tube and the L-shaped avoidance hole, respectively. The horizontal support tube positioning mechanism, the vertical tube positioning and clamping mechanism, and the five-way tube positioning and clamping mechanism are installed on the base plate and arranged around the outer edge of the L-shaped clearance hole.

[0006] The aforementioned welding fixture for the front triangle component of the children's bicycle frame includes a cross brace tube positioning mechanism with a cross brace tube positioning block and a cross brace tube positioning block front and rear position adjustment seat. The upper end of the cross brace tube positioning block front and rear position adjustment seat is assembled with the base plate, and the lower end is fitted with the cross brace tube positioning block. The cross brace tube positioning block has a cross brace tube positioning groove that matches the arc surface of the outer wall of the cross brace tube. The cross brace tube positioning block and the cross brace tube positioning block front and rear position adjustment seat are fixedly assembled in an angle-adjustable manner.

[0007] The aforementioned welding fixture for the front triangle component of the children's bicycle frame has upper and lower position adjustment holes on the front and rear position adjustment seat of the cross support tube positioning block in the cross support tube positioning mechanism. The upper and lower position adjustment holes of the cross support tube positioning block are two sets of parallel elongated holes.

[0008] The aforementioned welding fixture for the front triangle component of the children's bicycle frame includes a brace tube positioning block adjustment seat, a brace tube positioning block, and a downward clamping clamp in each part of the brace tube positioning and clamping mechanism. One end of the brace tube positioning block adjustment seat is assembled with the base plate, and the other end is fitted with the brace tube positioning block. The brace tube positioning block has a brace tube positioning groove that matches the arc surface of the outer wall of the brace tube. The brace tube positioning block is fixedly assembled with the brace tube positioning block adjustment seat in an angle-adjustable manner. The downward clamping clamp is mounted on the base plate, and the clamping head of the downward clamping clamp is arranged opposite to the brace tube positioning block.

[0009] The aforementioned welding fixture for the front triangle component of the children's bicycle frame has an adjustment hole for the position of the positioning block of the inclined support tube on the adjustment seat of the positioning and pressing mechanism of the inclined support tube. The adjustment hole for the position of the positioning block of the inclined support tube is an elongated hole extending along the adjustment direction.

[0010] The aforementioned welding fixture for the front triangle component of a children's bicycle frame includes a front tube positioning and tightening mechanism comprising a front tube positioning block assembly, a front tube positioning block angle adjustment seat, a movable seat, a fixed seat, and a side-push clamping clamp. The fixed seat is assembled with the base plate, and the side-push clamping clamp and the movable seat are mounted on the fixed seat. One end of the driven arm of the side-push clamping clamp is bolted to the movable seat, with one end of the bolt fixedly assembled to the movable seat and the other end screwed into the driven arm sleeve of the side-push clamping clamp. The movable seat is fitted with the front tube positioning block angle adjustment seat. The front tube positioning block assembly is mounted on the front tube positioning block angle adjustment seat.

[0011] The aforementioned welding fixture for the front triangle component of the children's bicycle frame has several horizontal support tube positioning mechanism assembly holes and diagonal support tube positioning and clamping mechanism assembly holes arranged around the L-shaped clearance hole on the base plate; the horizontal support tube positioning mechanism assembly holes are arranged parallel to the horizontal side of the L-shaped clearance hole; the diagonal support tube positioning and clamping mechanism assembly holes are arranged parallel to the rear vertical side of the L-shaped clearance hole.

[0012] This utility model provides a welding fixture for the front triangle component of a children's bicycle frame. Through the cooperation of a base assembly, a front tube positioning and clamping mechanism, a brace tube positioning and clamping mechanism, a cross brace tube positioning mechanism, a riser tube positioning and clamping mechanism, and a bottom bracket tube positioning and clamping mechanism, the front triangle component of the children's bicycle frame can be accurately positioned to ensure that the horizontal distance B between the front tube and the bottom bracket tube and the tilt angle θ of the brace tube meet the set value requirements. This utility model provides welding avoidance areas for the front tube and brace tube, as well as welding avoidance areas for the cross brace tube, riser tube, bottom bracket tube, and brace tube on the base plate of the base assembly. Assembled with the power output end of the welding station positioner, the workpiece can be clamped and welded on its upper surface when the base plate is horizontal. After the upper surface weld is completed, the positioner drives the base assembly and workpiece to rotate 180º to weld the lower surface weld. Since the cross brace tube in the front triangle of a children's bicycle frame serves to improve the overall strength of the frame, facilitate the movement of the bicycle, and enhance its appearance, its positional accuracy is not critical. Therefore, this invention only includes a front and rear position adjustment seat for the cross brace tube positioning block and the cross brace tube positioning block itself in the cross brace tube positioning mechanism. During the welding operation on the upper surface of the workpiece, the horizontal support tube positioning block supports and positions the middle part of the horizontal support tube. After the two ends of the upper surface of the horizontal support tube are welded to the diagonal support tube and the vertical tube respectively, the horizontal support tube is connected to the diagonal support tube and the vertical tube, ensuring reliable positioning of the horizontal support tube during the welding operation on the lower surface of the workpiece. Since there is no need to set up a separate horizontal support tube clamping element, it not only reduces the number of parts in the horizontal support tube positioning mechanism, but also makes the overall layout of this utility model more favorable. This utility model has several sets of diagonal support tube positioning block position adjustment seat assembly holes and horizontal support tube positioning block front and rear position adjustment holes on the base plate of the base assembly. The entire assembly hole also incorporates adjustable-angle positioning grooves for the diagonal brace tube positioning blocks and the cross brace tube positioning blocks. Furthermore, a bolt is incorporated into the driven arm sleeve of the side-push clamping pliers within the front tube positioning and tightening mechanism. Therefore, by adjusting the positions of the diagonal brace tube positioning block and cross brace tube positioning block adjustment seats, adjusting their angles, and adjusting the depth of the bolts screwed into the driven arm sleeve of the side-push clamping pliers in the front tube positioning and tightening mechanism, the assembly can accommodate the welding requirements of different models and specifications of children's bicycle frame front triangle components, exhibiting good versatility. In summary, this invention achieves reliable positioning of the front triangle component of a children's bicycle frame, thereby improving the quality of welded products and ensuring the consistency of the overall bicycle assembly dimensions. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the front triangle component of the children's bicycle frame involved in this utility model; Figure 2 yes Figure 1 Front view of the front triangle component of a children's bicycle frame; Figure 3 This is a schematic diagram of the welding fixture structure for the front triangle component of a children's bicycle frame; Figure 4 This is a top view of the welding fixture for the front triangle component of a children's bicycle frame; Figure 5 This is a schematic diagram of the base assembly structure (top view); Figure 6 This is a schematic diagram (top view) of the front tube positioning and clamping mechanism; Figure 7 This is a schematic diagram of the inclined support tube positioning and clamping mechanism (top view of the rear part). Figure 8 This is a schematic diagram (top view) of the cross brace positioning mechanism; Figure 9 This is a schematic diagram (top view) of the working state of this utility model.

[0014] Explanation of each label in the diagram: 1 is the front triangular component, 1-1 is the front tube, 1-2 is the diagonal brace tube, 1-3 is the horizontal brace tube, 1-4 is the riser tube, and 1-5 is the bottom bracket tube; 2 is the base assembly, 2-1 is the base plate, 2-2 is the welding clearance area between the front tube and the diagonal brace tube, 2-3 is the L-shaped clearance hole, 2-4 is the assembly hole for the positioning mechanism of the cross brace tube, and 2-5 is the assembly hole for the positioning and clamping mechanism of the diagonal brace tube. 3 is the front tube positioning and clamping mechanism, 3-1 is the front tube positioning block assembly, 3-2 is the front tube positioning block angle adjustment seat, 3-3 is the movable seat, 3-4 is the fixed seat, 3-5 is the side-push clamping clamp, and 3-6 is the bolt. 4 is the positioning and clamping mechanism for the diagonal brace tube; 4-1 is the position adjustment seat for the diagonal brace tube positioning block; 4-2 is the positioning block for the diagonal brace tube; 4-3 is the positioning groove for the diagonal brace tube; 4-4 is the position adjustment hole for the diagonal brace tube positioning block; 4-5 is the downward clamping clamp. 5 is the horizontal support tube positioning mechanism, 5-1 is the front and rear position adjustment seat of the horizontal support tube positioning block, 5-2 is the upper and lower position adjustment hole of the horizontal support tube positioning block, 5-3 is the horizontal support tube positioning block, and 5-4 is the horizontal support tube positioning groove. 6 is the riser positioning and clamping mechanism; 7 is the positioning and clamping mechanism for the five-way pipe. Detailed Implementation

[0015] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0016] See Figure 1. Figure 2A front triangle component 1 for a children's bicycle frame is disclosed. This front triangle component 1 comprises a front tube 1-1, a diagonal brace tube 1-2, a cross brace tube 1-3, a riser tube 1-4, and a bottom bracket tube 1-5. These components are assembled together by welding. The horizontal distance B between the front tube 1-1 and the bottom bracket tube 1-5, and the inclination angle θ of the diagonal brace tube 1-2, are important parameters for inspecting the welding process of the front triangle component 1 and serve as the basis for judging the quality of the welded workpiece. However, since the diagonal brace tube 1-2 is a curved tube with a large diameter, and the cross brace tube 1-3 is a structure specifically designed to improve the overall strength of the frame, facilitate the handling of the children's bicycle, and enhance its aesthetic appearance, traditional welding fixtures for the front triangle component of bicycle frames are difficult to match the special structure of this children's bicycle frame. Therefore, an innovative design for the welding fixture of this front triangle component is required.

[0017] See Figure 3 , Figure 4 , Figure 5 This utility model provides a welding fixture for the front triangle component of a children's bicycle frame, comprising a base assembly 2, a front tube positioning and tightening mechanism 3, a diagonal brace tube positioning and tightening mechanism 4, a cross brace tube positioning mechanism 5, a vertical tube positioning and tightening mechanism 6, and a bottom bracket tube positioning and tightening mechanism 7. The base assembly 2 is assembled with the power output end of the welding station positioner. A base plate 2-1 is provided in the base assembly 2. The base plate 2-1 is an L-shaped flat plate. The front tube positioning and tightening mechanism 3 is installed on the inner side of the long arm of the L-shaped flat plate. A welding avoidance area 2-2 between the front tube positioning and tightening mechanism 3 and the short arm of the L-shaped flat plate is formed between the front tube and the diagonal brace tube. Welding avoidance areas for the cross brace tube, vertical tube, bottom bracket tube, and diagonal brace tube are provided on the short arm of the L-shaped flat plate. The welding avoidance areas for the cross brace tube, vertical tube, bottom bracket tube, and diagonal brace tube are inverted L-shaped avoidance holes 2-3.

[0018] See Figure 3 , Figure 4 , Figure 6 The welding fixture for the front triangle component of the children's bicycle frame described in this utility model includes a front tube positioning and tightening mechanism 3 comprising a front tube positioning block assembly 3-1, a front tube positioning block angle adjustment seat 3-2, a movable seat 3-3, a fixed seat 3-4, and a side-push clamping clamp 3-5. The fixed seat 3-4 is assembled with the base plate 2-1, and the side-push clamping clamp 3-5 and the movable seat 3-3 are mounted on the fixed seat 3-4. One end of the driven arm of the side-push clamping clamp 3-5 is connected to the movable seat. 3-3 is connected by bolt 3-6. One end of bolt 3-6 is fixedly assembled with the movable seat 3-3, and the other end is screwed into the driven arm sleeve of the side-push clamping pliers 3-5. The front and rear positions of the front tube 1-1 can be adjusted by adjusting the depth of bolt 3-6 screwed into the driven arm sleeve of the side-push clamping pliers 3-5. The movable seat 3-3 is fitted with the front tube positioning block angle adjustment seat 3-2. The front tube positioning block assembly 3-1 is fitted on the front tube positioning block angle adjustment seat 3-2.

[0019] See Figure 3 , Figure 4 , Figure 7 The welding fixture for the front triangle component of the children's bicycle frame described in this utility model has a diagonal brace tube positioning and clamping mechanism 4 mounted on a base plate 2-1. It comprises two parts arranged front and rear, extending into the welding clearance area 2-2 between the front tube and the diagonal brace tube, and the L-shaped clearance hole 2-3, respectively. Each part is equipped with a diagonal brace tube positioning block adjustment seat 4-1, a diagonal brace tube positioning block 4-2, and a downward-pressing clamping clamp 4-5. One end of the diagonal brace tube positioning block adjustment seat 4-1 is connected to the base plate 2-1. 1. The other end is equipped with a diagonal brace tube positioning block 4-2; the diagonal brace tube positioning block 4-2 is provided with a diagonal brace tube positioning groove 4-3 that matches the arc surface of the outer wall of the diagonal brace tube. The diagonal brace tube positioning block 4-2 is fixedly assembled with the diagonal brace tube positioning block position adjustment seat 4-1 in an angle-adjustable manner. The angle-adjustable manner includes bolt assembly, set screw or snap-fit ​​assembly; the downward pressing clamp 4-5 is installed on the base plate 2-1, and the pressing head of the downward pressing clamp 4-5 is arranged opposite to the diagonal brace tube positioning block 4-2.

[0020] See Figure 3 , Figure 4 , Figure 8 The welding fixture for the front triangle component of the children's bicycle frame described in this utility model includes a cross brace tube positioning mechanism 5 with a cross brace tube positioning block 5-3 and a cross brace tube positioning block front and rear position adjustment seat 5-1. The upper end of the cross brace tube positioning block front and rear position adjustment seat 5-1 is assembled with the base plate 2-1, and the lower end is fitted with the cross brace tube positioning block 5-3. The cross brace tube positioning block 5-3 is provided with a cross brace tube positioning groove 5-4 that matches the arc surface of the outer wall of the cross brace tube 1-3. The cross brace tube positioning block 5-3 and the cross brace tube positioning block front and rear position adjustment seat 5-1 are fixedly assembled in an angle-adjustable manner. The angle-adjustable manner includes bolt assembly, set screw or snap-fit ​​assembly.

[0021] See Figure 5 , Figure 6 , Figure 7 , Figure 8The welding fixture for the front triangle component of a children's bicycle frame described in this utility model is designed to accommodate welding operations of front triangle components for children's bicycle frames of different specifications and models. It features several cross brace positioning mechanism assembly holes 2-4 and diagonal brace positioning and clamping mechanism assembly holes 2-5 around the L-shaped clearance hole 2-3 on the base plate 2-1. The cross brace positioning mechanism assembly holes 2-4 are arranged parallel to the horizontal side of the L-shaped clearance hole 2-3. Matching these holes, the cross brace positioning block positioning block front-rear position adjustment seat 5-1 of the cross brace positioning mechanism 5 is provided with cross brace positioning block up-down position adjustment holes 5-2. These holes are two sets of parallel elongated holes, allowing for adjustment of the front-rear and up-down positions of the cross brace positioning block 5-3 by engaging with different cross brace positioning mechanism assembly holes 2-4. The mounting holes 2-5 of the diagonal brace tube positioning and clamping mechanism are arranged parallel to the vertical side of the rear side of the L-shaped clearance hole 2-3, and are matched accordingly. The diagonal brace tube positioning block position adjustment seat 4-1 in the front and rear parts of the diagonal brace tube positioning and clamping mechanism 4 is provided with diagonal brace tube positioning block position adjustment holes 4-4. These diagonal brace tube positioning block position adjustment holes 4-4 are elongated holes extending along the adjustment direction. Therefore, the vertical position of the diagonal brace tube positioning block 4-2 can be adjusted by cooperating with different diagonal brace tube positioning and clamping mechanism mounting holes 2-5 using the diagonal brace tube positioning and clamping mechanism position adjustment holes 4-4. Furthermore, in this utility model structure, both the horizontal brace tube positioning block 5-3 and the diagonal brace tube positioning block 4-2 can be angled. In the front tube positioning and clamping mechanism 3, the front and rear positions of the front tube 1-1 can be adjusted by controlling the depth of the bolt 3-6 screwed into the side-push clamping pliers 3-5 from the boom sleeve. Therefore, it is easier to adapt to the front triangle components of different models and specifications of children's bicycle frames, thereby improving the versatility of this utility model.

[0022] See Figure 9The welding fixture for the front triangle component of a children's bicycle frame described in this utility model, before welding the front triangle component of the children's bicycle frame, uses a standard sample of the front triangle component as the debugging reference workpiece. First, the standard sample of bottom bracket 1-5 is positioned and pressed by the bottom bracket positioning and pressing mechanism 7, and the standard sample of riser 1-4 is positioned and pressed by the riser positioning and pressing mechanism 6. Then, using the positioned and pressed bottom bracket 1-5 and riser 1-4 as positioning references, according to the tilt angle θ of the diagonal brace 1-2, the position adjustment seat 4-1 of the diagonal brace positioning block and the angle of the diagonal brace positioning block 4-2 in the front and rear parts of the diagonal brace positioning and pressing mechanism 4 are adjusted according to the angle between the front tube 1-1 and the bottom bracket 1-5. The horizontal distance B between the front tubes requires adjustment of the angle and position of the front tube positioning block assembly 3-1 in the front tube positioning and clamping mechanism 3; then adjust the position of the front and rear position adjustment seat 5-1 of the cross support tube positioning block and the angle of the cross support tube positioning block 5-3; after completing the above adjustments, place and clamp or press the standard samples of the diagonal support tube 1-2, the front tube 1-1 and the cross support tube 1-3 with their corresponding positioning elements, and measure the horizontal distance B between the front tube 1-1 and the five-way tube 1-5 and the tilt angle θ of the diagonal support tube 1-2. When they meet the set value requirements, open the clamping elements of each corresponding part, disassemble the standard samples, and complete the adjustment work of each part of this utility model; then the workpiece clamping and welding operations can be carried out.

Claims

1. A welding fixture for the front triangle component of a children's bicycle frame, characterized in that: It is equipped with a base assembly (2), a front tube positioning and clamping mechanism (3), a diagonal brace tube positioning and clamping mechanism (4), a cross brace tube positioning mechanism (5), a riser tube positioning and clamping mechanism (6), and a five-way tube positioning and clamping mechanism (7). The base assembly (2) is assembled with the power output end of the welding station positioner. A base plate (2-1) is set in the base assembly (2). The base plate (2-1) is an L-shaped flat plate. A front tube positioning and tightening mechanism (3) is installed on the inner side of the long arm of the L-shaped flat plate. A welding avoidance area (2-2) between the front tube positioning and tightening mechanism (3) and the short arm of the L-shaped flat plate is formed between the front tube and the inclined support tube. A welding avoidance area for the horizontal support tube, the vertical tube, the five-way tube, and the inclined support tube is set on the short arm of the L-shaped flat plate. The welding avoidance area for the horizontal support tube, the vertical tube, the five-way tube, and the inclined support tube is an inverted L-shaped avoidance hole (2-3). The inclined support tube positioning and clamping mechanism (4) is installed on the base plate (2-1) and includes two parts arranged in front and back. The front and back parts extend into the welding avoidance area (2-2) between the front tube and the inclined support tube and the L-shaped avoidance hole (2-3), respectively. The horizontal support tube positioning mechanism (5), the vertical tube positioning and clamping mechanism (6) and the five-way tube positioning and clamping mechanism (7) are installed on the base plate (2-1) and arranged around the outer edge of the L-shaped clearance hole (2-3).

2. The welding fixture for the front triangle component of a children's bicycle frame according to claim 1, characterized in that: The cross brace positioning mechanism (5) is provided with a cross brace positioning block (5-3) and a cross brace positioning block front and rear position adjustment seat (5-1); the upper end of the cross brace positioning block front and rear position adjustment seat (5-1) is assembled with the base plate (2-1), and the lower end is equipped with the cross brace positioning block (5-3); the cross brace positioning block (5-3) is provided with a cross brace positioning groove (5-4) that matches the arc surface of the outer wall of the cross brace (1-3), and the cross brace positioning block (5-3) and the cross brace positioning block front and rear position adjustment seat (5-1) are fixedly assembled in an angle-adjustable manner.

3. The welding fixture for the front triangle component of a children's bicycle frame according to claim 2, characterized in that: The horizontal support tube positioning mechanism (5) has a horizontal support tube positioning block upper and lower position adjustment hole (5-2) on the front and rear position adjustment seat (5-1). The horizontal support tube positioning block upper and lower position adjustment hole (5-2) consists of two sets of parallel elongated holes.

4. The welding fixture for the front triangle component of a children's bicycle frame according to claim 2 or 3, characterized in that: Each part of the inclined support tube positioning and clamping mechanism (4) is provided with an inclined support tube positioning block position adjustment seat (4-1), an inclined support tube positioning block (4-2), and a downward clamping clamp (4-5); one end of the inclined support tube positioning block position adjustment seat (4-1) is assembled with the base plate (2-1), and the other end is equipped with the inclined support tube positioning block (4-2); the inclined support tube positioning block (4-2) is provided with an inclined support tube positioning groove (4-3) that matches the outer arc surface of the inclined support tube, and the inclined support tube positioning block (4-2) is fixedly assembled with the inclined support tube positioning block position adjustment seat 4-1 in an angle-adjustable manner; the downward clamping clamp (4-5) is installed on the base plate (2-1), and the pressure head of the downward clamping clamp (4-5) is arranged opposite to the inclined support tube positioning block (4-2).

5. The welding fixture for the front triangle component of a children's bicycle frame according to claim 4, characterized in that: The inclined support tube positioning block position adjustment seat (4-1) of the inclined support tube positioning and pressing mechanism (4) is provided with an inclined support tube positioning block position adjustment hole (4-4), which is an elongated hole extending along the adjustment direction.

6. The welding fixture for the front triangle component of a children's bicycle frame according to claim 5, characterized in that: The front tube positioning and clamping mechanism (3) includes a front tube positioning block assembly (3-1), a front tube positioning block angle adjustment seat (3-2), a movable seat (3-3), a fixed seat (3-4), and a side-push clamping clamp (3-5). The fixed seat (3-4) is assembled with the base plate (2-1), and the side-push clamping clamp (3-5) and the movable seat (3-3) are mounted on the fixed seat (3-4). One end of the driven arm of the side-push clamping clamp (3-5) is connected to the movable seat (3-3) by a bolt (3-6). One end of the bolt (3-6) is fixedly assembled with the movable seat (3-3), and the other end is screwed into the driven arm sleeve of the side-push clamping clamp (3-5). The movable seat (3-3) is fitted with the front tube positioning block angle adjustment seat (3-2). The front tube positioning block assembly (3-1) is mounted on the front tube positioning block angle adjustment seat (3-2).

7. The welding fixture for the front triangle component of a children's bicycle frame according to claim 6, characterized in that: A plurality of horizontal support tube positioning mechanism assembly holes (2-4) and diagonal support tube positioning and pressing mechanism assembly holes (2-5) are provided around the L-shaped clearance hole (2-3) of the base plate (2-1); the horizontal support tube positioning mechanism assembly holes (2-4) are arranged along the direction parallel to the horizontal side of the L-shaped clearance hole (2-3); the diagonal support tube positioning and pressing mechanism assembly holes (2-5) are arranged along the direction parallel to the vertical side of the rear side of the L-shaped clearance hole (2-3).

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