Bicycle frame welding process and processing line

Abstract

The application discloses a bicycle frame welding process and a processing line body, and belongs to the technical field of bicycle processing, which comprises the following steps: S100, positioning and welding a five-way pipe and a vertical pipe; S200, positioning and welding a lower pipe, the five-way pipe and the vertical pipe; S300, positioning and welding a front pipe and an upper pipe; S400, respectively positioning and welding the five-way pipe, the vertical pipe and the lower pipe and the front pipe and the upper pipe; S500, welding two upper fork pipes and a bridge pipe between the two upper fork pipes; S600, respectively positioning and welding two lower fork pipes and two ear pieces; S700, respectively positioning and welding a front triangular assembly, the lower fork pipes and the ear pieces; and S800, respectively welding two ends of the upper fork pipes and the vertical pipe and the ear pieces, so that the problems of many welding dead angles, stress superposition and positioning error accumulation are avoided, and the welding precision and the yield of the frame are improved.

Description

Technical Field

[0001] This invention belongs to the field of bicycle processing technology, specifically relating to a bicycle frame welding process and processing line. Background Technology

[0002] In the manufacturing of bicycle frames, multiple components such as the top tube, down tube, seat tube, front tube, bottom bracket, rear seat stay, and rear chain stay need to be welded into a complete frame according to the design positions. Traditional welding processes usually adopt a one-time clamping and centralized welding method, that is, all the components to be welded are simultaneously positioned and fixed on a set of tooling, and then the welding equipment welds each joint sequentially or simultaneously, completing the welding of the entire frame through S100 or two or three processes.

[0003] Chinese invention patent CN121402878A discloses "A bicycle frame welding process and equipment," which describes the following process steps in its specification: S1, pre-treatment of frame components and equipment inspection; S2, placing the pre-treated top tube, bottom tube, and riser on the arc-shaped support brackets of four sets of displacement components on the support platform, adjusting the spacing of the support brackets by sliding blocks to make the arc-shaped surface fit against the outer wall of the tube, and pressing the upper end face of the tube with the arc-shaped clamping component of the clamping assembly to firmly fix each tube; S3, starting the displacement assembly. The fixed tubing is transported to the cleaning station, where the inner and outer walls of the interface are wiped using the cleaning sponge of the cleaning component; S4, the bottom bracket tube, rear upper fork, rear lower fork, and rear dropout are introduced for assisted positioning and assembly. A special clamp is used to fix the bottom bracket tube in the designated position on the support platform. One end of the rear upper fork and rear lower fork is aligned with the two sides of the bottom bracket tube, and the other end is pre-connected to the rear dropout; S5, the welding robotic arm is started to automatically weld the various components of the frame. The welding tool welds each interface according to the preset welding path; S6, post-weld processing and quality inspection are performed. This solution completes the positioning and welding of the main tubing of the frame in one clamping, which is a typical centralized welding method.

[0004] This centralized welding method reduces the number of tooling fixtures and equipment footprint, offering a certain efficiency advantage when mass-producing the same model of chassis. However, in actual operation, this method has the following problems: First, the welding joints of the various tubes in the frame are distributed in different locations and directions in space. When multiple tubes are clamped simultaneously, they can easily obstruct each other, creating multiple welding dead zones. The welding torch needs to be frequently adjusted in angle and posture to bypass the obstructing tubes and reach the joint to be welded. Each time the welding torch angle is readjusted, a pause and repositioning are required, interrupting the welding continuity and prolonging the welding cycle of a single frame piece. Moreover, in some narrow areas, even after adjusting the angle, the welding torch cannot approach the weld in an ideal posture and can only be welded at an oblique angle. At an oblique angle, the wire feed direction and the coverage effect of the shielding gas in the molten pool are affected, resulting in a decrease in weld formation quality and a higher likelihood of welding defects such as incomplete fusion and porosity.

[0005] Secondly, the simultaneous clamping and welding of multiple pipes on the same fixture results in a high concentration of heating zones in both time and space, leading to a rapid increase in the overall temperature of the workpiece due to the cumulative welding heat input. The different wall thicknesses of the various pipes in the frame result in varying degrees of thermal expansion; thicker-walled pipes heat up slowly and expand less, while thinner-walled pipes heat up quickly and expand more. This mutual constraint between the pipes generates significant welding stress. After welding, the workpiece cools at different rates, with the earlier-cooled areas contracting under the constraint of the later-cooled areas, further exacerbating residual stress. The release of this residual stress can cause overall or localized deformation of the frame, deviating the relative angles and positions between the frame pipes from design values ​​and affecting subsequent assembly accuracy. For frames requiring post-weld heat treatment or surface finishing, residual stress may be released a second time in subsequent processes, causing the already treated frame to deform again, increasing rework costs.

[0006] Secondly, during concentrated welding in a single clamping setup, multiple pipe fittings are positioned on the same fixture, and the positioning references of each fitting are interconnected. When the first joint to be welded is completed, the weld cools and shrinks, causing a slight displacement. This displacement is transmitted through the fixture to other unwelded fittings, causing a shift in the positioning reference of subsequent welded joints. As each joint is welded sequentially, positioning errors accumulate at each stage, and the cumulative positioning deviation of the last welded joint may exceed the design tolerance range. For symmetrical structures such as the rear triangle of the chassis, the asymmetrical accumulation of positioning errors on the left and right sides can lead to chassis skew, causing the rear wheels to not coincide with the center plane of the chassis after installation, affecting the vehicle's driving stability. When positioning deviations occur, operators need to loosen the clamps and readjust the pipe fitting positions; repeated adjustments and trial welds further reduce production efficiency.

[0007] Finally, during concentrated welding, multiple welds are applied consecutively within a short period. The residual heat of one weld has not yet dissipated before the next weld begins, resulting in overlapping heat-affected zones (HAZs). This exacerbates grain coarsening within the HAZs, reducing the strength and toughness of the weld joint. For critical stress-bearing areas where multiple pipes intersect, such as the junction of the bottom bracket, riser, or downpipe, the overlap of HAZs can lead to a decrease in fatigue strength in that area, potentially becoming the initiation point for fatigue cracks during long-term vehicle use. Summary of the Invention

[0008] The purpose of this invention is to provide a bicycle frame welding process and processing line, which avoids problems such as multiple welding dead angles, stress superposition and positioning error accumulation by breaking down the process and designing the sequence, thereby improving the welding accuracy and yield of the frame.

[0009] To achieve the above objectives, embodiments of the present invention provide a bicycle frame welding process, including: S100, positioning and welding the bottom bracket and the stem; S200: Position the lower pipe and the welded bottom pipe and riser, and weld one end of the lower pipe to the bottom pipe; S300, position and weld the front tube and the top tube; S400: The welded bottom bracket, riser, and downpipe are positioned and welded together with the welded front pipe and top pipe to form the front triangle assembly. The S500 welds two upper fork tubes to the bridge tube located between the two upper fork tubes to form the rear triangular upper fork. S600, the two lower fork tubes are positioned and welded to the two lugs respectively; For the S700, the front triangle assembly, the welded lower fork tubes, and the lugs are positioned separately, and the bottom bracket is welded to one end of each of the two lower fork tubes. S800, weld the two ends of one upper fork tube to the riser and one lug respectively, and weld the two ends of the other upper fork tube to the riser and another lug respectively.

[0010] In one possible implementation, in S100, the upper part of the joint between the riser and the bottom bracket is welded, so that the lower part of the riser and the bottom bracket is reserved for splicing with the end of the lower pipe.

[0011] In one possible implementation, the bottom bracket and riser, which have been welded by S100, are placed and fixed horizontally, and the bottom bracket is placed and fixed at an angle so that the lower end of the bottom bracket is against the side wall of the bottom bracket. The lower half of the riser and the bottom bracket, as well as the splice part of the bottom bracket and the bottom bracket, are then welded.

[0012] The present invention also provides a bicycle frame processing line, which uses the above-mentioned bicycle frame welding process and further includes: An end stop for clamping a bottom bracket in S100, S200, S400 and S700, the end stop having an abutment surface for abutting the end of the bottom bracket, an inner support protrusion provided on the abutment surface, the inner support protrusion being cylindrical and extending outward along the axial direction of the abutment surface, the outer diameter of the inner support protrusion being configured to clearance fit with the inner diameter of the bottom bracket for insertion into the interior of the bottom bracket to form a radial stop.

[0013] In one possible implementation, the end limiting member is provided with an exhaust groove or an axially penetrating exhaust hole, so that when the abutting surface abuts with the end of the bottom bracket, the exhaust groove or exhaust hole can connect the inside and outside of the bottom bracket.

[0014] In one possible implementation, the end stop member in S100 is provided with a positioning block that extends outward along the axial direction of the contact surface. The positioning block is configured such that when the contact surface abuts against the end of the riser, the positioning block is inserted into the notch of the riser.

[0015] In one possible implementation, the end stop is also used to clamp the front tube in S300 and S400.

[0016] In one possible implementation, S700 also includes: The ear piece has an insertion part for insertion into the lower fork port in the S700 to limit the lower fork axially and circumferentially. Two sets of position adjustment components are used to fix the ear piece in the S700. Each set of position adjustment components includes a first clamping rod and a second clamping rod. The first clamping rod and the second clamping rod are both horizontally movable and can move closer to or further away from each other. The first clamping rod includes an abutment rod and an insertion rod connected to each other. The insertion rod is located at the end of the abutment rod facing the second clamping rod. A slot is provided on the lug. The diameter of the insertion rod is adapted to the width of the slot so that the insertion rod and the slot can be clearance-fitted. The abutment rod and the second clamping rod are used to clamp the lug from both axial end faces respectively.

[0017] In one possible implementation, in S700, the end face of the second clamping rod facing the first clamping rod has an axially formed insertion hole, which is configured such that when the abutment rod and the second clamping rod clamp the lug, the insertion rod is inserted into the insertion hole.

[0018] In one possible implementation, S700 also includes: Two side stops are used to place the rear triangle lower fork between the two side stops. The two side stops are used to abut against the two lower fork tubes respectively. The side stops can move horizontally. A stopper is placed on the side of the side stop away from the rear triangle lower fork. The stopper abuts against the peripheral wall of the side stop to apply abutting force toward the lower fork tube.

[0019] This invention provides a bicycle frame welding process and processing line. Steps S100 and S200 first weld the bottom bracket, riser, and downtube to construct the core load-bearing frame, concentrating welding stress in a smaller area and gradually releasing it. Steps S300 and S400 complete the welding of the front triangle. Steps S500 to S800 progressively weld the rear triangle and the entire bicycle. Each sequence is clamped independently, and the positioning reference is re-established each time. The deformation deviation caused by welding in step S100 is corrected in the current sequence, and positioning errors are not propagated across sequences. Compared to the existing method of concentrated welding in a single clamping, this process, through process splitting and sequential design, avoids problems such as numerous welding dead angles, stress superposition, and accumulated positioning errors, thus improving the welding accuracy and yield of the frame. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the process steps of a bicycle frame welding process in one embodiment of the present invention; Figure 2 This is a schematic diagram of the tooling structure of a bicycle frame processing line S100 in one embodiment of the present invention; Figure 3 This is a schematic diagram of the tooling structure of a bicycle frame processing line S200 in one embodiment of the present invention; Figure 4 This is a schematic diagram of the tooling structure of a bicycle frame processing line S300 in one embodiment of the present invention; Figure 5 This is a schematic diagram of the tooling structure of a bicycle frame processing line S400 in one embodiment of the present invention; Figure 6 This is a schematic diagram of the tooling structure of a bicycle frame processing line S500 in one embodiment of the present invention; Figure 7 This is a schematic diagram of the tooling structure of a bicycle frame processing line S600 in one embodiment of the present invention; Figure 8 This is a schematic diagram of the tooling structure of a bicycle frame processing line S700 in one embodiment of the present invention; Figure 9 This is a schematic diagram of the tooling structure of a bicycle frame processing line S800 in one embodiment of the present invention; Figure 10This is a schematic diagram of the position adjustment component in the tooling of the present invention S700; Figure 11 This is a partial structural diagram of the tooling end limiting member and the riser insertion of the S100 of the present invention; Figure 12 This is a schematic diagram of the ear piece structure of the present invention; Figure 13 This is a schematic diagram of the side stop, the abutment, and the mounting base in the tooling of the S700 of the present invention. Figure 14 A schematic diagram of the structure of the end limiting member of the present invention with an exhaust hole; Figure 15 A schematic diagram of the structure of the end limiting member of the present invention with an exhaust groove.

[0022] In the diagram: 100, frame body; 110, bottom bracket tube; 120, seat tube; 121, notch; 130, downtube; 140, front tube; 150, top tube; 160, upper stay tube; 170, bridge tube; 180, lower stay tube; 190, lug; 191, slot. 200. End limiting component; 210. Abutment surface; 220. Inner support protrusion; 230. Vent groove; 240. Vent hole; 250. Alignment block; 300, Position adjustment assembly; 310, First clamping rod; 311, Abutting rod; 312, Insertion rod; 320, Second clamping rod; 321, Insertion hole; 400, side guard; 500, abutment. Detailed Implementation

[0023] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0025] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0026] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0027] In the description of the embodiments of this application, the term "and / or" is merely a description of the association relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship. In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple groups" refers to two or more groups (including two groups), and "multiple pieces" refers to two or more pieces (including two pieces).

[0028] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0029] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation", "connection", "linking", and "fixing" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components.

[0030] In the manufacturing of bicycle frames, multiple tubing components, such as the top tube 150, down tube 130, seat tube 120, front tube 140, bottom bracket 110, rear seat stays, rear chain stays, and lugs 190, need to be welded to form the main frame body 100 according to the designed positions. In existing technologies, the main frame tubing is typically positioned and welded in a single clamping operation, a typical centralized welding method. To address the centralized welding method and its associated problems, this embodiment provides a bicycle frame welding process that breaks down the frame welding into eight steps. Each step is independently clamped and positioned according to the welding sequence from core to periphery and from bottom to top, avoiding the accumulation of thermal stress and positioning errors caused by centralized welding.

[0031] Reference Figure 1 Specifically, in S100, the bottom bracket 110 and riser 120 are welded. Both bottom bracket 110 and riser 120 are placed horizontally, with the end of riser 120 against the side wall of bottom bracket 110. The upper half of the joint between riser 120 and bottom bracket 110 is welded, leaving space in the lower half for the joint with the end of lower pipe 130. If bottom bracket 110 and riser 120 are fully welded in S100, a raised weld bead will form. When the end of lower pipe 130 is against bottom bracket 110, the weld bead causes an uneven contact surface, creating an assembly gap. This gap is difficult to completely fill with the weld during S200 welding, resulting in a weak weld or incomplete fusion. Welding the upper half first, then the lower half, ensures that the welded surface is the original pipe surface each time, avoiding interference from already welded seams on subsequent assembly and welding quality.

[0032] S200: Weld the lower pipe 130 to the already welded bottom bracket 110 and riser 120. Place and fix the bottom bracket 110 and riser 120 (after welding in S100) horizontally, and fix the lower pipe 130 at an angle so that the lower end of the lower pipe 130 is against the side wall of the bottom bracket 110. Weld the lower half of the riser 120 to the bottom bracket 110 and the joint between the lower pipe 130 and the bottom bracket 110.

[0033] S300, weld the front tube 140 and the upper tube 150. Place the front tube 140 horizontally and fix it, and place the upper tube 150 at an angle and fix it so that the lower end of the upper tube 150 is against the side wall of the front tube 140. Weld the splice part of the upper tube 150 and the front tube 140.

[0034] In step S400, the bottom five-way pipe 110, riser 120, and lower pipe 130, which were welded in step S200, are assembled and positioned with the front pipe 140 and upper pipe 150, which were welded in step S300, and the front triangle assembly is welded. The front triangle assembly includes the head pipe, upper pipe 150, lower pipe 130, riser 120, and bottom five-way pipe 110. The above-mentioned pipe fittings are positioned and fixed in one clamping, and the welding of each joint is completed.

[0035] S500, the two upper fork tubes 160 are welded to the bridge tube 170 located between the two upper fork tubes 160 to form the rear triangular upper fork. During welding, the joint between the upper fork tubes 160 and the bridge tube 170 is welded, and the initial shape of the triangular upper fork is completed.

[0036] In the S600, two lower fork tubes 180 are welded to two lugs 190 respectively. The rear ends of the two lower fork tubes 180 are welded to the left and right lugs 190 respectively to form the left and right parts of the rear triangle lower fork. The left and right parts are welded separately, and symmetrical control is used to avoid frame tilting caused by asymmetrical welding of the left and right lower forks.

[0037] In S700, the lower fork tube 180 and lug 190, which were welded in S600, are welded to the bottom bracket tube 110. The connection between the assembly formed by welding the lower fork tube 180 and lug 190 and the bottom bracket tube 110 is one of the parts of the frame that bears a lot of stress. Welding at this point is completed through a separate process to ensure the connection strength.

[0038] In S800, one end of each of the two upper fork tubes 160 in the rear triangle upper fork is welded to the two lugs 190 in S600, and the other end is welded to the seat tube 120. A support is installed under the upper fork to provide balanced support for the component, and it is fixed by an upper clamp. After welding the component at both the front and rear positions, the welding operation of the entire bicycle frame is completed.

[0039] S100 and S200 first weld the bottom bracket 110, riser 120, and downtube 130 to construct the core load-bearing frame of the chassis, concentrating welding stress in a smaller area and gradually releasing it. S300 and S400 complete the welding of the front triangle body. S500 to S800 progressively weld the rear triangle and the entire vehicle. Each sequence is clamped independently, and the positioning reference is re-established each time it is clamped. The deformation deviation caused by welding in the upper S100 is corrected in the clamping of the current sequence, and the positioning error between sequences will not be transmitted across sequences. Compared with the existing technology of concentrated welding in one clamping, this process avoids the problems of multiple welding dead corners, stress superposition, and positioning error accumulation through process splitting and sequential design, thereby improving the welding accuracy and yield of the chassis.

[0040] Please see Figures 2-14 On the other hand, the present invention also provides a bicycle frame processing line that uses the above-mentioned bicycle frame welding process and is equipped with special tooling for each process.

[0041] In the machining example, during the frame welding process, steps S100, S200, S400, and S700 all involve clamping and fixing the bottom bracket 110. In traditional tooling, the end-positioning member 200 clamping the bottom bracket 110 is usually a flat plate structure with a flat abutment surface 210, relying on end-face friction to axially position the bottom bracket 110. Under the influence of welding heat, the bottom bracket 110 expands due to heat. Because the pipe wall is relatively thin, the end-face friction is insufficient to limit the radial displacement of the bottom bracket 110, and the bottom bracket 110 is prone to slight radial displacement, causing the welding interface position to deviate from the preset position and affecting the weld accuracy. To address this problem, the end-positioning member 200 used in this example adds an inner support protrusion 220 to the abutment surface 210. The inner support protrusion 220 is cylindrical and extends outward along the axial direction of the abutment surface 210, and its outer diameter is configured to have a clearance fit with the inner diameter of the bottom bracket 110. When the contact surface 210 abuts against the end of the five-way pipe 110, the inner support protrusion 220 is inserted into the interior of the five-way pipe 110. There is a small gap between the outer circumferential surface of the inner support protrusion 220 and the inner wall of the five-way pipe 110, which facilitates the smooth insertion of the inner support protrusion 220 into the five-way pipe 110 and also limits the five-way pipe 110 in the radial direction. Compared with the traditional method that relies solely on end-face friction, the inner support protrusion 220 forms a mechanical radial constraint after being inserted into the pipe. Even if the pipe expands due to welding heat, the position of the five-way pipe 110 in the radial direction is still limited by the inner support protrusion 220, and no radial displacement will occur, thus improving the accuracy of the weld position.

[0042] In a further example, in traditional tooling, the contact surface 210 of the end limiting member 200 is flat. When the contact surface 210 is pressed against the end face of the five-way pipe 110, the internal cavity of the five-way pipe 110 is sealed by the end limiting member 200, forming a relatively closed space. During welding, the heat from the welding torch is conducted to the five-way pipe 110, causing the air inside the five-way pipe 110 to expand due to heat. However, because both ends of the cavity are sealed, the expanding gas cannot escape, and the gas pressure inside the cavity increases. After welding is completed and the cooling stage begins, the gas inside the five-way pipe 110 gradually cools and contracts, reducing the gas pressure inside the cavity and creating a negative pressure. The external atmospheric pressure then presses the end limiting member 200 against the end face of the five-way pipe 110, increasing the friction between them. Simultaneously, the high welding temperature may also cause localized adhesion between the end face of the five-way pipe 110 and the contact surface 210. The combination of these factors makes it difficult for the end limiting member 200 to detach from the end of the five-way pipe 110 after welding, requiring operators to spend considerable time removing the workpiece. To address this issue, in this example, the end limiting member 200 has an exhaust groove 230 on its contact surface 210, or an axially penetrating exhaust hole 240. When the contact surface 210 abuts against the end of the five-way pipe 110, the exhaust groove 230 or exhaust hole 240 connects the inside and outside of the five-way pipe 110. During welding, the air inside the five-way pipe 110 expands due to heat, and the expanded gas is discharged to the outside atmosphere through the exhaust groove 230 or exhaust hole 240, preventing the generation of high pressure inside the pipe cavity. During cooling, external air is replenished into the five-way pipe 110 through the exhaust groove 230 or exhaust hole 240, preventing the generation of negative pressure inside the pipe cavity. Since the internal cavity of the five-way pipe 110 is always connected to the outside atmosphere, and the air pressure is consistent with the external environment, no additional clamping force is generated between the end limiting member 200 and the end face of the five-way pipe 110 due to the air pressure difference. After welding, the end limiting member 200 can easily detach from the end of the five-way pipe 110. Compared with the traditional structure of a closed cavity, the setting of the exhaust groove 230 or exhaust hole 240 eliminates the generation of air pressure difference and solves the problem of difficult disassembly.

[0043] In a further example, in S100, when welding the bottom bracket 110 and the riser 120, a notch 121 is typically cut at one end of the riser 120. This notch 121 is used to install transmission components such as the bottom bracket and crankset. The angle at which the notch 121 is cut on the circumference of the bottom bracket 110 is required, and it needs to maintain an accurate relative angle with the welding direction of the riser 120. In traditional welding methods, operators usually manually place the end of the riser 120 against the side wall of the bottom bracket 110 and weld directly. During welding, the riser 120 is prone to circumferential rotation due to thermal expansion and the thrust of the welding torch, causing the angle of the notch 121 to deviate from the preset position. If the angle of the notch 121 deviates, the mating position between the transmission components and other parts of the frame will deviate from the design value when installing transmission components such as the bottom bracket, resulting in malfunction of the transmission system and requiring rework and adjustment. To address this issue, the end limiter 200 used in S100 in this example is also equipped with an alignment block 250. The alignment block 250 extends outward along the axial direction of the abutment surface 210. When the abutment surface 210 abuts against the end of the riser 120, the alignment block 250 is inserted into the notch 121 of the riser 120. The fit between the alignment block 250 and the notch 121 mechanically limits the circumferential rotational freedom of the riser 120, ensuring that the notch 121 remains at a preset angle position throughout the welding process. Compared with traditional manual straightening, the alignment block 250 achieves mechanical locking through shape fit, and the accuracy of the notch 121 angle is not affected by the operator's experience or welding process vibrations, thus improving welding consistency and the assembly accuracy of subsequent transmission components.

[0044] Further examples, in S300 and S400, involve the clamping and fixing of the front tube 140. The front tube 140 is a short, round tube, and conventional tooling also uses a flat plate abutment method for clamping, which suffers from the same air pressure difference as when clamping the bottom bracket 110, leading to difficulties in disassembly. In this example, the end limiter 200 is also used to clamp the front tube 140 in S300 and S400. The inner support protrusion 220 is inserted into the interior of the front tube 140 to form a radial limit, and the vent groove 230 or vent hole 240 ensures that the internal cavity of the front tube 140 is always connected to the outside during welding, thus avoiding the difficulties in disassembly caused by air pressure changes due to the closed cavity.

[0045] In S700, the lower fork tube 180 and lug 190, welded in S600, have formed a single assembly. The task of S700 is to weld this assembly to the bottom bracket tube 110. Therefore, the tooling in S700 is to fix this assembly and ensure its positional stability during the welding process in S700. Traditional tooling for fixing such assemblies often uses bolts to lock its base plate to the base frame. This single-point fixing method makes the assembly prone to slight angular deflection around the bolt axis under the influence of welding vibration and thermal expansion, resulting in a deviation in the welding position of the assembly relative to the bottom bracket tube 110. To address this issue, in this example, the processing line of S700 includes two sets of position adjustment assemblies 300. Each set of position adjustment assemblies 300 includes a first clamping rod 310 and a second clamping rod 320, both of which are horizontally movable on the base frame and can move closer to or further away from each other. The first clamping rod 310 includes an abutment rod 311 and an insertion rod 312 connected to each other, and a slot 191 is provided on the lug 190. By horizontal movement, the insertion rod 312 can pass through the slot 191, and the abutment rod 311 and the second clamping rod 320 can clamp it from both axial end faces of the lug 190.

[0046] In a further example, when the abutment rod 311 and the second clamping rod 320 clamp the lug 190, the insertion rod 312 passes through the slot 191 of the lug 190 and continues to extend into the insertion hole 321 on the end face of the second clamping rod 320. At this time, the cooperation between the insertion rod 312 and the insertion hole 321 locks the first clamping rod 310 and the second clamping rod 320 together in the radial direction. Compared with the traditional single-point fixing, this double-point locking method enhances the stability of clamping, so that the lower fork tube 180 assembly, which is welded to the lug 190, will not undergo angular deflection or shaking under the action of welding vibration and thermal expansion, thereby ensuring that the assembly can be stably maintained in the preset relative position with the bottom bracket 110 during S700 welding.

[0047] In a further example, in S700, the two lower fork tubes 180 of the rear triangular lower fork need to be laterally restrained from both sides to prevent lateral displacement during welding. In traditional tooling, the side stops 400 are usually fixed to the base frame by bottom bolts, relying solely on the friction between the bolts and the tooling base surface to resist the lateral thrust of the lower fork tubes 180 on the side stops 400 during welding. Under the influence of prolonged welding heat input, the temperature of the tooling base surface rises, the preload of the bolts decreases due to thermal expansion, and the friction is insufficient. The side stops 400 are prone to slipping outward under the lateral thrust, causing the lower fork tubes 180 to lose lateral support, the welding joint position to shift, and affecting the weld quality. To address this problem, the processing line of S700 in this embodiment also includes two side stops 400. The rear triangle lower fork is positioned between the two side stops 400. Each side stop 400 abuts against one of the two lower fork tubes 180. The side stops 400 are horizontally movable on the base frame. By adjusting the distance between the two side stops 400, rear triangle lower forks of different widths can be accommodated. An abutment 500 is positioned on the side of the side stop 400 away from the rear triangle lower fork. The abutment 500 can be a bolt or screw. The end of the abutment 500 abuts against the peripheral wall of the side stop 400 to apply an abutment force towards the lower fork tube 180. Compared with the traditional method of fixing by the friction of the bottom bolts alone, the abutment 500 directly applies mechanical pushing force from the outside of the side stop 400. The direction of this pushing force is opposite to the direction of the pushing force of the lower fork tube 180 on the side stop 400 during welding. The two cancel each other out, and the position of the side stop 400 is not affected by welding vibration and thermal expansion. The lateral positioning of the lower fork tube 180 remains stable during the welding process, and the accuracy of the weld position is improved.

[0048] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of protection of the claims of the present invention.

Claims

1. A bicycle frame welding process for welding and forming a bicycle frame, characterized in that, include: S100, Position and weld the bottom bracket (110) and riser (120); S200, Position the lower pipe (130) and the welded five-way pipe (110) and riser (120) and weld one end of the lower pipe (130) to the five-way pipe (110); S300, Position and weld the front tube (140) and the upper tube (150); S400, the welded bottom five pipe (110), riser (120), and lower pipe (130) are positioned and welded with the welded front pipe (140) and upper pipe (150) to form the front triangle assembly; S500, the two upper fork tubes (160) are welded to the bridge tube (170) located between the two upper fork tubes (160) to form the rear triangular upper fork; S600, the two lower fork tubes (180) are positioned and welded to the two lugs (190) respectively; S700, the front triangle assembly and the welded lower fork tube (180) and lug (190) are positioned respectively, and the bottom bracket tube (110) is welded to one end of the two lower fork tubes (180); S800, the two ends of one upper fork tube (160) are welded to the riser (120) and one lug (190) respectively, and the two ends of the other upper fork tube (160) are welded to the riser (120) and the other lug (190) respectively.

2. The bicycle frame welding process according to claim 1, characterized in that, In S100, one end of the riser (120) is welded to the upper half of the five-way pipe (110) at the abutment, so that the lower half of the abutment is reserved for splicing with the end of the lower pipe (130).

3. The bicycle frame welding process according to claim 2, characterized in that, When welding the lower pipe (130) to the five-way pipe (110), the following are included: Place and fix the welded bottom bracket (110) and riser (120) in a horizontal position. Place the bottom pipe (130) at an angle and place the lower end of the bottom pipe (130) against the side wall of the bottom bracket (110). Weld the half of the riser (120) and bottom bracket (110) near the bottom pipe (130) and the part of the bottom pipe (130) that is in contact with the bottom bracket (110).

4. A bicycle frame processing line, characterized in that, include: An end limiting member (200) is used to clamp a bottom bracket (110). The end limiting member (200) has an abutment surface (210) for abutting against the end of the bottom bracket (110). One side of the end limiting member (200) has an axially extending inner support protrusion (220) for inserting into the interior of the bottom bracket (110) to form a radial limit on the bottom bracket (110).

5. A bicycle frame processing line according to claim 4, characterized in that, The end limiting member (200) is provided with an exhaust groove (230), the exhaust groove (230) penetrates the inner support protrusion (220) and the bottom of the groove is recessed in the abutment surface (210), the exhaust groove (230) penetrates the peripheral wall of the end limiting member (200) radially, so that when the abutment surface (210) abuts with the end of the five-way pipe (110), the exhaust groove (230) can connect the inside and outside of the five-way pipe (110).

6. A bicycle frame processing line according to claim 4, characterized in that, The end limiting member (200) is provided with an axially penetrating vent hole (240) so that when the abutting surface (210) abuts against the end of the five-way pipe (110), the vent hole (240) can connect the inside and outside of the five-way pipe (110).

7. A bicycle frame processing line according to claim 5 or 6, characterized in that, An alignment block (250) is provided on the end limiting member (200). The alignment block (250) protrudes outward from the end limiting member (200) in the circumferential direction. The alignment block (250) is configured such that when the abutting surface (210) abuts against the end of the riser (120), the alignment block (250) is inserted into the notch (121) of the riser (120).

8. A bicycle frame processing line according to claim 7, characterized in that, Also includes: Two sets of position adjustment components (300), each set of position adjustment components (300) includes a first clamping rod (310) and a second clamping rod (320), the first clamping rod (310) and the second clamping rod (320) are both horizontally movable and can move closer to each other to clamp the ear piece (190) from both sides; The first clamping rod (310) includes an abutment rod (311) and an insertion rod (312) connected to each other. The insertion rod (312) is located at the outer end of the abutment rod (311) and is used to insert into the slot (191) of the ear piece (190).

9. A bicycle frame processing line according to claim 8, characterized in that, The second clamping rod (320) has an insertion hole (321) along the axial direction. The insertion hole (321) is configured such that when the abutment rod (311) and the second clamping rod (320) clamp the ear piece (190), the insertion rod (312) is inserted into the insertion hole (321).

10. A bicycle frame processing line according to claim 9, characterized in that, Also includes: Two side stops (400) are provided, with two lower fork tubes (180) placed between the two side stops (400), and the two side stops (400) are respectively used to abut against the two lower fork tubes (180), and the side stops (400) are capable of horizontal movement; An abutment (500) is placed outside the side stop (400) and abuts against the peripheral wall of the side stop (400) to apply an abutment force toward the lower fork tube (180) to the side stop (400).

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