Welding tool for child balance car

Abstract

The invention relates to the technical field of welding tools, in particular to a welding tool for a child balance car. High-precision positioning of the child balance car frame is achieved through cooperation of the seven assemblies. The head pipe positioning assembly establishes a 0.5-degree precision reference by utilizing bidirectional coaxial constraint; a horizontal rotating shaft of the lower pipe angle positioning frame is dynamically coupled with a main beam positioning hole, so that millimeter-level dislocation of a front triangular structure is eliminated; the second welding piece is supported by the bottom face of the supporting groove, limited by the inner side face of the groove and combined with two-way locking of the positioning piece to guarantee all-around attachment of the connecting face. The symmetrical deviation of the rear fork is compressed to + / -0.3 degrees through axial positioning of a conical pin, vertical suppression of a pressing block and thermal deformation correction of an elastic strip; the rear lower fork is limited in a self-adaptive mode through the supporting groove to prevent lateral movement. The frame middle body positioning assembly is controlled through synchronous force application of three pressing pieces. And the efficiency of the whole-process single-station welding operation is improved by 40%.

Description

Technical Field

[0001] This invention relates to the field of welding fixture technology, and in particular to a welding fixture for children's balance bikes. Background Technology

[0002] The welding fixture for children's balance bikes is a positioning clamping system specifically designed for frame welding. Its core function is to precisely position and fix the head tube, main beam, rear fork, and other components of the frame through multiple sets of linkage mechanisms, ensuring that each component maintains a preset spatial angle and relative position during the high-temperature welding process, ultimately achieving the geometric accuracy and welding strength requirements of the frame structure.

[0003] Existing welding fixtures have significant drawbacks in practical applications: First, the synchronous positioning accuracy of multiple frame components is insufficient. A children's balance bike frame consists of more than ten tubes and connecting pieces, including the head tube, down tube, main beam, and rear fork. Traditional fixtures use a step-by-step independent locking method. When the welder sequentially fixes the head tube positioning pin, main beam pressure plate, and welding piece stop, the tubes sag due to their own weight or mechanical vibration, causing slight displacement and resulting in misalignment between the spatial coordinates of the head tube positioned earlier and the main beam pressed together later. In particular, the first and second welding pieces need to be positioned separately by pushing with cylinders; the asynchronous driving of these two components causes axial misalignment, resulting in excessive weld gaps at the junction of the main beam and the front tube. Second, the symmetry control of the rear fork fails. The upper and lower rear forks need to be mirror-symmetrical with respect to the frame's central axis, but conventional fixtures rely solely on a single-sided tapered pin inserted into the upper rear fork's tube hole for positioning, while the lower rear fork on the other side is supported by a passive support groove. The high temperature during welding caused the tubing to shrink locally. Because there was no active clamping mechanism, the rear lower fork slid laterally along the support groove, which eventually caused the horizontal projection angle of the two rear fork arms to deviate from the design value by more than ±1.5°. This caused the whole vehicle to veer off course after the wheelset was installed, and the user had to repeatedly adjust the wheel spoke tension to barely correct the trajectory.

[0004] Therefore, this application provides a welding fixture for children's balance bikes to solve the problems mentioned in the background art. Summary of the Invention

[0005] The purpose of this invention is to provide a welding fixture for children's balance bikes, which solves the problems of existing welding fixtures causing cumulative positioning errors of frame components due to step-by-step locking, and the passive support structure of the rear upper fork and rear lower fork being unable to suppress welding thermal deformation, resulting in large symmetrical deviations on both sides.

[0006] To solve the above-mentioned technical problems, the present invention provides a welding fixture for a children's balance bike, including a horizontally arranged welding platform, and a head tube positioning assembly, a lower tube angle positioning frame, a main beam positioning assembly, a second welding piece positioning assembly, a rear upper fork positioning assembly, a rear lower fork support assembly, and a frame midbody fixing assembly arranged sequentially on the welding platform. The frame of the children's balance bike includes a head tube, a down tube, an arc-shaped main beam, two symmetrically distributed upper rear forks, two symmetrically distributed lower rear forks, a first welded plate, and a second welded plate. The first welded plate consists of two symmetrically spliced ​​trapezoidal pieces used to connect the head tube, down tube, and main beam. The waist edge of the first welded plate is in contact with the arc surface of the main beam and the down tube, respectively, and the upper base edge is in contact with the arc surface of the head tube. The second welded plate is a near-obtuse triangle used to connect the upper rear forks and the lower rear forks. The obtuse angle side of the second welded plate is in contact with the arc surface of the upper rear forks and the lower rear forks, respectively. The head tube positioning assembly is located at the center of the front end of the welding platform and is used to position the coaxiality of the head tube. The lower tube angle positioning bracket is located behind the head tube positioning assembly and is used to fix the connection angle between the lower tube and the head tube. The main beam positioning assembly is located in the middle of the welding platform and is used to support the main beam and position its end. The second welding piece positioning assembly is located at the rear of the welding platform and includes a second welding piece support block that supports the second welding piece and a positioning piece that positions and positions it, and is used to fix the connection point between the upper and lower forks. The upper fork positioning assembly includes a tapered pin for the upper fork located at the rear end of the welding platform and a spring bar that corrects the upper fork from above, used for axial positioning and deformation correction, respectively. The lower fork support assembly is located in the middle of the welding platform and is used to support the lower fork and limit its inner displacement. The frame mid-body fixing assembly is located on both sides of the middle of the welding platform and is used to simultaneously fix the relative positions of the main beam, upper fork, and lower fork.

[0007] A further improvement of the technical solution of the present invention is that: the head tube positioning assembly includes a first cylinder fixed at the center of the front end of the welding platform, the piston rod of the first cylinder is connected to a tapered head tube positioning pin, the axis of the head tube positioning pin is at a fixed angle to the vertical line, the angle corresponds to the design and installation angle of the head tube of the child balance bike frame, a cylindrical positioning block is embedded in the inner wall of the lower end of the head tube, the positioning block is interference-fitted with the head tube, the head tube positioning pin is clearance-fitted with the inner cavity of the upper end of the head tube, and the first cylinder drives the head tube positioning pin to extend and insert into the upper end of the head tube, so that the head tube positioning pin, the positioning block and the head tube are coaxial.

[0008] A further improvement of the technical solution of the present invention is that: the lower tube angle positioning frame includes a horizontal rotating shaft fixed to the rear side of the head tube positioning assembly. The rotating shaft is inserted into the lower tube positioning hole preset at the lower end of the lower tube, fixing the height position of the lower end of the lower tube and constraining it to rotate only around the shaft; the upper end of the lower tube abuts against the lower side wall of the head tube, and the upper arc surface of the lower tube is completely in contact with the waist arc surface of the first welding piece. The other side waist of the first welding piece is in contact with the front arc surface of the main beam, and the upper bottom edge is in contact with the middle arc surface of the head tube. The three form a stable front triangular welding structure under the constraint of the head tube positioning assembly and the lower tube angle positioning frame.

[0009] A further improvement of the technical solution of the present invention is that: the main beam positioning assembly includes a cuboid main beam positioning frame fixed in the middle of the welding platform, the top of the main beam positioning frame is provided with a circular main beam positioning hole adapted to the outer diameter of the end of the main beam, and a horizontal main beam positioning plate is fixed at the bottom of the main beam positioning frame; the front end of the arc-shaped main beam fits against the waist of the first welding piece, the end is inserted into the main beam positioning hole, the lower end face of the main beam completely abuts against the main beam positioning plate, and the main beam positioning plate is fixed to the welding platform by bolts to ensure that the main beam maintains the preset arc-shaped posture during the welding process.

[0010] A further improvement of the technical solution of the present invention is that: the second welding piece positioning assembly includes a support block fixed in the center of the rear of the welding platform, two symmetrical L-shaped support grooves are opened on both sides of the top of the support block, the bottom surface of the support groove is in contact with the bottom edge of the second welding piece for support, and the inner side of the support groove restricts the second welding piece from moving inward; two sets of horizontal second cylinders are symmetrically arranged on both sides of the rear of the welding platform, each set of second cylinders is located on the outer side of the second welding piece, the piston rod of the second cylinder is connected to the positioning piece, the positioning piece is bent to form a horizontal support edge and a vertical baffle, the support edge supports the bottom of the second welding piece, the baffle abuts against the outer side of the second welding piece, restricts the second welding piece from moving outward, and ensures that the obtuse angle edge of the second welding piece is completely in contact with the arc surface of the upper rear fork and the lower rear fork respectively.

[0011] A further improvement of the technical solution of the present invention is that: the rear upper fork positioning assembly includes a third cylinder disposed at the rear end of the welding platform; the rear end of the rear upper fork is a straight steel pipe, the front end of which is bent into a contact arc surface adapted to the arc surface of the middle part of the main beam, and the contact arc surface is completely attached to both sides of the middle part of the main beam; the third cylinder is horizontally fixed at the rear end of the welding platform, and its piston rod is connected to two symmetrical tapered pins, the two tapered pins are respectively coaxially disposed with the corresponding rear upper fork, the tapered pins are clearance-fitted with the round hole at the end of the rear upper fork, and the third cylinder drives the tapered pins to be inserted into the end of the rear upper fork synchronously, positioning the axial length and left-right symmetry of the rear upper fork.

[0012] A further improvement of the technical solution of the present invention is that: the rear upper fork positioning component also includes a fourth cylinder, the fourth cylinder is vertically fixed in the middle of the welding platform, the piston rod of the fourth cylinder is connected to a rectangular pressure block, the pressure block acts on the rear quarter of the rear upper fork, and the two ends of the pressure block are provided with semi-circular arc grooves that are adapted to the outer diameter of the rear upper fork. The fourth cylinder drives the pressure block to move downward, and the arc groove completely fits the outer wall of the rear upper fork, restricting the vertical movement of the rear upper fork.

[0013] A further improvement of the technical solution of the present invention is that: the rear upper fork positioning assembly also includes a fifth cylinder, which is vertically fixed above the middle of the rear upper fork. The piston rod of the fifth cylinder is connected to a horizontal connecting plate. Four stainless steel spring bars are fixed at the bottom of the connecting plate. Each rear upper fork corresponds to two spring bars. Each spring bar is arc-shaped. The two ends of the spring bar abut against the upper side of the rear upper fork and extend axially towards the rear upper fork. The fifth cylinder drives the connecting plate to move up and down, and the elastic deformation of the spring bars corrects the welding deformation of the rear upper fork.

[0014] A further improvement of the technical solution of the present invention is that: the rear lower fork is an arc-shaped steel pipe, the top of which is welded to the middle of the rear upper fork and is completely in contact with the obtuse angle side arc surface of the second welding piece; the end of the rear lower fork abuts against the two outer sides of the main beam positioning component; the rear lower fork support component includes a rear lower fork support block fixed to the rear side of the main beam positioning component, the rear lower fork support block acts at the rear quarter of the rear lower fork, and L-shaped rear lower fork support grooves are symmetrically opened on both sides of the rear lower fork support block; the lower side of the rear lower fork is embedded in the rear lower fork support groove, the bottom surface of the rear lower fork support groove supports the rear lower fork, and the inner side of the rear lower fork support groove restricts the rear lower fork from moving inward, thus ensuring the symmetry of the two rear lower forks.

[0015] A further improvement of the technical solution of the present invention is that: two sets of frame mid-body fixing components are provided, located on both sides of the middle of the welding platform and next to the rear lower fork respectively; each set of frame mid-body fixing components includes a horizontally arranged sixth cylinder, the piston rod of the sixth cylinder is connected to a rectangular mounting plate, and three rubber pressure plates are fixed on the mounting plate, namely a first pressure plate abutting the side of the main beam, a second pressure plate abutting the side of the rear upper fork, and a third pressure plate abutting the side of the rear lower fork; the sixth cylinder drives the mounting plate to move towards the frame, and the three pressure plates simultaneously press the main beam, the rear upper fork, and the rear lower fork to ensure that the three maintain their relative positions during the welding process.

[0016] By adopting the above technical solution, the present invention has the following beneficial effects: 1. This invention provides a welding fixture for a children's balance bike. The welding fixture forms a bidirectional coaxial positioning structure through a head tube positioning pin and a positioning block in a head tube positioning assembly. A first cylinder drives the head tube positioning pin to insert into the upper inner cavity of the head tube, while the positioning block is interference-fitted against the lower inner wall of the head tube. The two components form a double constraint on the head tube along the axial direction, ensuring that the error between the head tube axis and the designed installation angle does not exceed 0.5°, providing a high-precision reference for welding the front triangular structure of the frame.

[0017] 2. The present invention provides a welding fixture for a children's balance bike. This welding fixture forms a dynamic angle coupling mechanism through the rotating shaft of the lower tube angle positioning frame and the main beam positioning hole of the main beam positioning assembly. The rotating shaft is inserted into the lower tube positioning hole of the lower tube to constrain the rotational freedom of the lower tube. This, combined with the radial limiting of the end of the main beam by the main beam positioning hole on the main beam positioning frame and the tilt angle locking of the lower end face of the main beam by the main beam positioning plate, ensures that the upper arc surface of the lower tube, the waist edge of the first welding piece, and the front arc surface of the main beam remain in a coplanar contact state, eliminating misalignment defects caused by step welding at the joint between the main beam and the lower tube.

[0018] 3. The present invention provides a welding fixture for a child balance bike. This welding fixture forms a bidirectional dynamic locking system through the inner side of the support groove of the support block of the second welding piece positioning assembly and the positioning piece driven by the second cylinder. The inner side of the support groove prevents the second welding piece from displacing inward, the support edge of the positioning piece supports the bottom of the second welding piece, and the baffle abuts against the outer wall of the second welding piece, so as to achieve a gapless fit between the obtuse angle edge of the second welding piece and the arc surface of the rear upper fork and rear lower fork, thus solving the problem of axial misalignment caused by asynchronous pressing in traditional fixtures.

[0019] 4. The present invention provides a welding fixture for a children's balance bike, which implements triple coordinated control through the tapered pin, pressure block, and elastic strip of the rear upper fork positioning component. The third cylinder drives two tapered pins to be inserted synchronously into the circular hole at the end of the rear upper fork to position axial symmetry; the fourth cylinder drives the arc groove of the pressure block to press down the rear section of the rear upper fork to suppress vertical displacement; and the fifth cylinder drives the connecting plate to move the elastic strip to elastically press against the upper surface of the rear upper fork to correct welding deformation, compressing the horizontal projection angle deviation of the rear upper fork from ±1.5° to ±0.3°.

[0020] 5. The present invention provides a welding fixture for a children's balance bike. This welding fixture constructs an adaptive limiting system through the side surface and bottom surface of the rear lower fork support groove of the rear lower fork support assembly. The bottom surface of the rear lower fork support groove supports the gravity load of the rear lower fork, and the inner side surface of the rear lower fork support groove prevents the rear lower fork from displacing towards the central axis of the frame, ensuring that the top of the rear lower fork is constantly pressed against the obtuse angle side of the second welding piece, thus eliminating the phenomenon of lateral slippage of the rear lower fork exceeding 0.5mm caused by high welding temperature.

[0021] 6. The present invention provides a welding fixture for a children's balance bike, which integrates a three-pressure plate synchronous pressing mechanism through the mounting plate of the frame mid-body positioning component. The sixth cylinder drives the mounting plate to move the first pressure plate to abut against the side of the main beam, the second pressure plate to clamp the side of the upper rear fork, and the third pressure plate to press against the side of the lower rear fork. The three pressure plates apply force synchronously under the action of the rubber buffer layer, instantly locking the spatial position of the intersection of the main beam, the upper rear fork, and the lower rear fork, eliminating the micron-level cumulative displacement caused by step-by-step operation.

[0022] 7. This invention provides a welding fixture for children's balance bikes. This fixture achieves one-time coordinated positioning of all frame components through a spatial topology optimization layout of the head tube positioning assembly, lower tube angle positioning frame, main beam positioning assembly, second welding piece positioning assembly, rear upper fork positioning assembly, rear lower fork support assembly, and frame mid-body positioning assembly. Each component is arranged sequentially along the welding platform's workflow, starting from the front triangular structure of the first welding piece of the frame, through positioning at the connection point of the second welding piece, to symmetry control of the rear fork, and finally locked in place by the frame mid-body positioning assembly. This integrates the traditional multi-step welding process into a single-station continuous operation, improving efficiency by 40% and eliminating reference drift caused by process transitions. Attached Figure Description

[0023] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 This is an overall schematic diagram of a welding fixture for children's balance bikes; Figure 2 for Figure 1 The front view; Figure 3 This is a schematic diagram of the vehicle frame structure of the present invention; Figure 4 This is a schematic diagram of the structure of the first welding piece of the present invention; Figure 5 This is a schematic diagram of the structure of the second welding piece of the present invention; Figure 6 This is a schematic diagram of the head tube positioning assembly of the present invention; Figure 7 This is a schematic diagram of the structure of the lower tube angle positioning frame and the main beam positioning assembly of the present invention; Figure 8 for Figure 7 An enlarged schematic diagram of part A in the middle; Figure 9 for Figure 7 The front view; Figure 10 This is a schematic diagram of the structure of the second welding piece positioning assembly and the rear upper fork positioning assembly of the present invention; Figure 11 This is a schematic diagram of the installation of the support block and the second welding piece of the present invention; Figure 12 This is a schematic diagram of the installation of the second cylinder and the second welding piece of the present invention; Figure 13 for Figure 12 Enlarged schematic diagram of part B in the middle; Figure 14 This is a schematic diagram of the positioning plate of the present invention; Figure 15 This is a schematic diagram of the installation of the third cylinder, the fourth cylinder, and the rear upper fork of the present invention; Figure 16 for Figure 15 An enlarged schematic diagram of section C; Figure 17 This is a schematic diagram of the installation of the fifth cylinder and the rear upper fork of the present invention; Figure 18 for Figure 17 An enlarged schematic diagram of section D in the middle; Figure 19 This is a schematic diagram of the elastic bar structure of the present invention; Figure 20 This is a schematic diagram of the structure of the rear lower fork support assembly and the frame mid-body positioning assembly of the present invention; Figure 21 This is a schematic diagram showing the installation of the sixth cylinder of the present invention with the vehicle frame; Figure 22 for Figure 21 An enlarged schematic diagram of section E in the middle; Figure 23 for Figure 21 A structural diagram from another angle.

[0025] Reference numerals: 1. Frame; 11. Head tube; 12. Down tube; 13. Main beam; 14. Rear upper fork; 15. Rear lower fork; 16. First welded piece; 17. Second welded piece; 2. Welding platform; 3. Head tube positioning assembly; 31. First cylinder; 32. Head tube positioning pin; 33. Positioning block; 4. Down tube angle positioning bracket; 41. Rotary shaft; 42. Down tube positioning hole; 5. Main beam positioning assembly; 51. Main beam positioning bracket; 52. Main beam positioning hole; 53. Main beam positioning plate; 6. Second welded piece positioning assembly; 61. Support block; 62. Support groove; 63. 64. Support groove bottom surface; 65. Support groove inner side surface; 66. Second cylinder; 67. Positioning plate; 68. Support edge; 79. Baffle plate; 70. Rear upper fork positioning assembly; 71. Third cylinder; 72. Tapered pin; 73. Fourth cylinder; 74. Pressure block; 75. Arc groove; 76. Fifth cylinder; 77. Connecting plate; 78. Spring bar; 80. Rear lower fork support assembly; 81. Rear lower fork support block; 82. Rear lower fork support groove; 91. Frame mid-body positioning assembly; 92. Sixth cylinder; 93. Mounting plate; 94. First pressure plate; 95. Second pressure plate; 96. Third pressure plate. Detailed Implementation

[0026] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0028] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0029] The present invention will be further explained below with reference to specific embodiments.

[0030] like Figures 1-23 As shown, this embodiment provides a welding fixture for a child balance bike, including a horizontally arranged welding platform 2, and a head tube positioning assembly 3, a lower tube angle positioning frame 4, a main beam positioning assembly 5, a second welding piece positioning assembly 6, a rear upper fork positioning assembly 7, a rear lower fork support assembly 8, and a frame midbody fixing assembly 9, which are sequentially arranged on the welding platform 2. The child balance bike frame 1 includes a head tube 11, a lower tube 12, an arc-shaped main beam 13, two symmetrically distributed rear upper forks 14, and two symmetrically distributed... The rear lower fork 15, the first welding piece 16, and the second welding piece 17; the first welding piece 16 is two symmetrically spliced ​​trapezoidal pieces used to connect the head tube 11, the lower tube 12, and the main beam 13. The waist edge of the first welding piece 16 is in contact with the arc surface of the main beam 13 and the lower tube 12, respectively, and the upper bottom edge is in contact with the arc surface of the head tube 11; the second welding piece 17 is a near-obtuse triangle used to connect the rear upper fork 14 and the rear lower fork 15. The obtuse angle side of the second welding piece 17 is in contact with the arc surface of the rear upper fork 14 and the rear lower fork 15, respectively.

[0031] like Figures 1-3 , Figure 6As shown, in this embodiment, the head tube positioning assembly 3 is located at the center of the front end of the welding platform 2 and is used to position the coaxiality of the head tube 11. The head tube positioning assembly 3 includes a first cylinder 31 fixed at the center of the front end of the welding platform 2. The piston rod of the first cylinder 31 is connected to a tapered head tube positioning pin 32. The axis of the head tube positioning pin 32 is at a fixed angle to the vertical line. This angle corresponds to the design installation angle of the head tube 11 of the children's balance bike frame 1. A cylindrical positioning block 33 is embedded in the inner wall of the lower end of the head tube 11. The positioning block 33 is interference-fitted with the head tube 11. The head tube positioning pin 32 is clearance-fitted with the inner cavity of the upper end of the head tube 11. The first cylinder 31 drives the head tube positioning pin 32 to extend and insert into the upper end of the head tube 11, so that the head tube positioning pin 32, the positioning block 33 and the head tube 11 are coaxial, ensuring that the error between the axis of the head tube 11 and the design installation angle does not exceed 0.5°, providing a high-precision reference for welding the front triangle structure of the frame 1.

[0032] like Figures 1-3 , Figure 7 As shown, in this embodiment, the lower tube angle positioning frame 4 is located behind the head tube positioning assembly 3 and is used to fix the connection angle between the lower tube 12 and the head tube 11. The lower tube angle positioning frame 4 includes a horizontal rotating shaft 41 fixed behind the head tube positioning assembly 3. The rotating shaft 41 is inserted into the lower tube positioning hole 42 preset at the lower end of the lower tube 12, fixing the height position of the lower end of the lower tube 12 and constraining it to rotate only around the shaft. The upper end of the lower tube 12 abuts against the lower side wall of the head tube 11, and the upper arc surface of the lower tube 12 is completely in contact with the waist arc surface of the first welding piece 16. The other side waist of the first welding piece 16 is in contact with the front arc surface of the main beam 13, and the upper bottom edge is in contact with the middle arc surface of the head tube 11. The three form a stable front triangular welding structure under the constraint of the head tube positioning assembly 3 and the lower tube angle positioning frame 4, eliminating the misalignment defect caused by the step welding at the joint of the main beam 13 and the lower tube 12. like Figures 1-3 , Figure 7 , Figure 8 As shown, in this embodiment, the main beam positioning component 5 is located in the middle of the welding platform 2 and is used to support the main beam 13 and position its end. The main beam positioning component 5 includes a cuboid main beam positioning frame 51 fixed in the middle of the welding platform 2. The top of the main beam positioning frame 51 is provided with a circular main beam positioning hole 52 that matches the outer diameter of the end of the main beam 13. A horizontal main beam positioning plate 53 is fixed at the bottom of the main beam positioning frame 51. The front end of the arc-shaped main beam 13 is attached to the waist of the first welding piece 16, and the end is inserted into the main beam positioning hole 52. The lower end face of the main beam 13 is completely against the main beam positioning plate 53. The main beam positioning plate 53 is fixed to the welding platform 2 by bolts to ensure that the main beam 13 maintains the preset arc-shaped posture during the welding process and avoids the accumulation of deformation caused by gravity.

[0033] like Figures 1-3 , Figures 10-14As shown, in this embodiment, the second welding piece positioning assembly 6 is located at the rear of the welding platform 2, including a second welding piece support block supporting the second welding piece 17 and a positioning piece 66 for positioning its position and angle, used to fix the connection point between the upper rear fork 14 and the lower rear fork 15; the second welding piece positioning assembly 6 includes a support block 61 fixed in the center of the rear of the welding platform 2, with two symmetrical L-shaped support grooves 62 on both sides of the top of the support block 61, the bottom surface 63 of the support groove fitting against the bottom edge of the second welding piece 17 for support, and the inner side surface 64 of the support groove restricting the second welding piece 17 from moving inward; the welding platform 2 rear Two sets of horizontal second cylinders 65 are symmetrically arranged on both sides of the part. Each set of second cylinders 65 is located on the outside of the second welding piece 17. The piston rod of the second cylinder 65 is connected to the positioning piece 66. The positioning piece 66 is bent to form a horizontal support edge 67 and a vertical baffle 68. The support edge 67 supports the bottom of the second welding piece 17, and the baffle 68 abuts against the outside of the second welding piece 17, restricting the second welding piece 17 from moving outward and ensuring that the obtuse angle edge of the second welding piece 17 is fully fitted with the arc surface of the upper rear fork 14 and the lower rear fork 15, respectively, thus solving the problem of axial misalignment caused by asynchronous pressing in traditional tooling.

[0034] like Figures 1-3 , Figure 15 , Figure 16 As shown, in this embodiment, the rear upper fork positioning component 7 achieves precise symmetrical positioning through triple collaborative control. The rear end of the rear upper fork 14 is a straight steel pipe, and its front end is bent into a mating arc surface that matches the arc surface of the middle part of the main beam 13. The mating arc surface is completely fitted to both sides of the middle part of the main beam 13. The rear upper fork positioning component 7 includes a third cylinder 71 set at the rear end of the welding platform 2. The third cylinder 71 is horizontally fixed at the rear end of the welding platform 2. Its piston rod is connected to two symmetrical tapered pins 72. The two tapered pins 72 are respectively coaxially set with the corresponding rear upper fork 14. The tapered pins 72 are clearance-fitted with the round holes at the end of the rear upper fork 14. The third cylinder 71 drives the tapered pins 72 to be inserted into the end of the rear upper fork 14 synchronously, positioning the axial length and left-right symmetry of the rear upper fork 14, ensuring that the error of the axial length and left-right symmetry is less than ±0.3°.

[0035] like Figures 1-3 , Figure 15 , Figure 16 As shown, in this embodiment, the rear upper fork positioning assembly 7 also includes a fourth cylinder 73, which is vertically fixed in the middle of the welding platform 2. The piston rod of the fourth cylinder 73 is connected to a rectangular pressure block 74, which acts on the rear quarter of the rear upper fork 14. The pressure block 74 has semi-circular arc grooves 75 at both ends that are adapted to the outer diameter of the rear upper fork 14. The fourth cylinder 73 drives the pressure block 74 to move downward, and the arc grooves 75 completely fit the rear outer wall of the rear upper fork 14, effectively suppressing vertical displacement.

[0036] like Figures 1-3 , Figures 17-19As shown, in this embodiment, the rear upper fork positioning assembly 7 also includes a fifth cylinder 76, which is vertically fixed above the middle of the rear upper fork 14. The piston rod of the fifth cylinder 76 is connected to a horizontal connecting plate 77. Four stainless steel spring bars 78 are fixed at the bottom of the connecting plate 77. Each rear upper fork 14 corresponds to two spring bars 78. Each spring bar 78 is arc-shaped. The two ends of the spring bar 78 abut against the upper side of the rear upper fork 14 and extend axially towards the rear upper fork 14. The fifth cylinder 76 drives the connecting plate 77 to move up and down. The distributed pressure generated by the arc structure of the spring bar 78 is used to correct the welding heat deformation in real time, compressing the horizontal projection angle deviation of the rear upper fork 14 from the traditional ±1.5° to ±0.3°.

[0037] like Figures 1-3 , Figure 7 , Figure 8 As shown, in this embodiment, the rear lower fork support assembly 8 constructs an adaptive limiting system to ensure the stability of the rear fork; the rear lower fork support assembly 8 is located in the middle of the welding platform 2, used to support the rear lower fork 15 and limit its inner displacement; the rear lower fork 15 is an arc-shaped steel pipe, the top of which is welded to the middle of the rear upper fork 14 and completely fits the obtuse angle arc surface of the second welding piece 17, and the end of the rear lower fork 15 abuts against the two outer sides of the main beam positioning assembly 5, forming a stable mechanical transmission path; the rear lower fork support assembly 8 includes a rear lower fork support block 81 fixed to the rear side of the main beam positioning assembly 5, and ... The lower fork support block 81 acts on the rear quarter of the rear lower fork 15. The rear lower fork support block 81 has symmetrical L-shaped rear lower fork support grooves 82 on both sides. The lower side of the rear lower fork 15 is embedded in the rear lower fork support groove 82. The bottom surface 83 of the rear lower fork support groove supports the rear lower fork 15. The inner side surface 84 of the rear lower fork support groove restricts the rear lower fork 15 from moving inward. This double constraint keeps the top of the rear lower fork 15 and the obtuse angle side of the second welding piece 17 under constant pressure, successfully eliminating the 0.5mm-level lateral slippage caused by the high temperature of welding, and ensuring the welding position accuracy of the rear lower fork 15.

[0038] like Figures 1-3 , Figures 21-23As shown, in this embodiment, the frame mid-body fixing assembly 9 is located on both sides of the middle of the welding platform 2, and is used to simultaneously fix the relative positions of the main beam 13, the upper rear fork 14, and the lower rear fork 15. Two sets of frame mid-body fixing assemblies 9 are provided, located on both sides of the middle of the welding platform 2 and next to the lower rear fork 15, respectively. Each set of frame mid-body fixing assemblies 9 includes a horizontally arranged sixth cylinder 91. The piston rod of the sixth cylinder 91 is connected to a rectangular mounting plate 92. Three rubber pressure plates are fixed on the mounting plate 92, namely a first pressure plate 93 abutting the side of the main beam 13, a second pressure plate 94 abutting the side of the upper rear fork 14, and a third pressure plate 95 abutting the side of the lower rear fork 15. The sixth cylinder 91 drives the mounting plate 92 to move towards the frame 1, and the three pressure plates simultaneously press the main beam 13, the upper rear fork 14, and the lower rear fork 15, instantly locking the spatial position of the intersection of the main beam 13, the upper rear fork 14, and the lower rear fork 15, eliminating the micron-level cumulative displacement caused by step-by-step operation. The rubber buffer layer absorbs mechanical vibration while providing constant clamping force, preventing rigid contact from damaging the pipe surface.

[0039] This invention also provides the working principle of a welding fixture for children's balance bikes: The operator first inserts the lower end of the head tube 11 of the frame 1 into the interference fit positioning block 33, placing it at a preset fixed angle at the front end of the welding platform 2; then, the head tube positioning assembly 3 is activated, and the first cylinder 31 drives the tapered head tube positioning pin 32 to insert into the upper end inner cavity of the head tube 11, forming a bidirectional coaxial constraint with the lower positioning block 33, thus establishing the front triangle reference axis of the frame 1. Next, the lower tube 12 is installed, and its lower end positioning hole 42 is fitted into the horizontal rotating shaft 41, causing the upper arc surface of the lower tube 12 to automatically conform to the waist of the first welding piece 16; simultaneously, the end of the main beam 13 is inserted into the circular main beam positioning hole 52 of the main beam positioning frame 51, with the lower end surface of the main beam 13 abutting against the main beam positioning plate 53, and the front arc surface of the main beam 13 tightly conforming to the other waist of the first welding piece 16, completing the dynamic angle locking of the front triangle structure. Next, the second welded piece 17 is placed in the L-shaped support groove 62 of the support block 61. The bottom surface 63 of the support groove supports its bottom edge, and the inner side surface 64 of the support groove restricts inward movement. The second cylinder 65 drives the support edge 67 of the positioning piece 66 to lift the bottom of the second welded piece 17, and the baffle 68 presses against the outer wall to achieve bidirectional locking. At this time, the front end of the rear upper fork 14 is placed against the middle of the main beam 13. The third cylinder 71 drives the double conical pin 72 to be inserted into the round hole at the end of the rear upper fork 14 for axial symmetry. The fourth cylinder 73 drives the pressure block 74 to press down, and its arc groove 75 covers the rear section of the rear upper fork 14 to suppress vertical displacement. The fifth cylinder 76 drives the elastic strip 78 to elastically press against the upper surface of the rear upper fork 14 to correct deformation. The top of the rear lower fork 15 is attached to the obtuse angle edge of the second welded piece 17, and the bottom end is embedded in the rear lower fork support groove 82. The bottom surface 83 of the groove bears the weight, and the inner side surface 84 of the groove prevents lateral movement. Finally, the frame mid-body positioning component 9 is activated. The sixth cylinder 91 pushes the mounting plate 92, causing the first pressure plate 93 to abut against the main beam 13, the second pressure plate 94 to clamp the upper fork 14, and the third pressure plate 95 to press the lower fork 15. The three pressure plates simultaneously lock the spatial position of the mid-body node of the frame 1. After all components have completed positioning in coordination, continuous welding operations are carried out.

[0040] Finally, 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 the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A welding fixture for children's balance bikes, characterized in that: It includes a horizontally set welding platform (2), and a head tube positioning assembly (3), a lower tube angle positioning frame (4), a main beam positioning assembly (5), a second welding piece positioning assembly (6), a rear upper fork positioning assembly (7), a rear lower fork support assembly (8), and a frame midbody fixing assembly (9) arranged sequentially on the welding platform (2). The frame (1) of the children's balance bike includes a head tube (11), a bottom tube (12), an arc-shaped main beam (13), two symmetrically distributed upper rear forks (14), two symmetrically distributed lower rear forks (15), a first welded piece (16), and a second welded piece (17). The first welded piece (16) is two symmetrically spliced ​​trapezoidal pieces used to connect the head tube (11), the bottom tube (12), and the main beam (13). The waist edge of the first welded piece (16) is in contact with the arc surface of the main beam (13) and the bottom tube (12), and the upper bottom edge is in contact with the arc surface of the head tube (11). The second welded piece (17) is a near-obtuse triangle used to connect the upper rear forks (14) and the lower rear forks (15). The obtuse angle side of the second welded piece (17) is in contact with the arc surface of the upper rear forks (14) and the lower rear forks (15). The head tube positioning assembly (3) is located at the center of the front end of the welding platform (2) and is used to position the coaxiality of the head tube (11); the lower tube angle positioning frame (4) is located behind the head tube positioning assembly (3) and is used to fix the connection angle between the lower tube (12) and the head tube (11); the main beam positioning assembly (5) is located in the middle of the welding platform (2) and is used to support the main beam (13) and position its end position. The second welding piece positioning assembly (6) is located at the rear of the welding platform (2), including a second welding piece support block that supports the second welding piece (17) and a positioning piece (66) that positions and angles the second welding piece (17), used to fix the connection point between the upper rear fork (14) and the lower rear fork (15); the upper rear fork positioning assembly (7) includes a tapered pin (72) for the upper rear fork (14) located at the rear end of the welding platform (2) and a spring bar (78) that corrects the upper rear fork (14) from above, used for axial positioning and deformation correction, respectively; the lower rear fork support assembly (8) is located in the middle of the welding platform (2), used to support the lower rear fork (15) and limit its inner displacement; the frame midbody fixing assembly (9) is located on both sides of the middle of the welding platform (2), used to simultaneously fix the relative positions of the main beam (13), the upper rear fork (14), and the lower rear fork (15).

2. The welding fixture for a children's balance bike according to claim 1, characterized in that: The head tube positioning assembly (3) includes a first cylinder (31) fixed at the center of the front end of the welding platform (2). The piston rod of the first cylinder (31) is connected to a tapered head tube positioning pin (32). The axis of the head tube positioning pin (32) is at a fixed angle to the vertical line. This angle corresponds to the design installation angle of the head tube (11) of the child balance bike frame (1). A cylindrical positioning block (33) is embedded in the inner wall of the lower end of the head tube (11). The positioning block (33) is interference-fitted with the head tube (11). The head tube positioning pin (32) is clearance-fitted with the inner cavity of the upper end of the head tube (11). The first cylinder (31) drives the head tube positioning pin (32) to extend and insert into the upper end of the head tube (11), so that the head tube positioning pin (32), the positioning block (33) and the head tube (11) are coaxial.

3. The welding fixture for a children's balance bike according to claim 1, characterized in that: The lower tube angle positioning frame (4) includes a horizontal rotating shaft (41) fixed on the rear side of the head tube positioning assembly (3). The rotating shaft (41) is inserted into the lower tube positioning hole (42) at the lower end of the lower tube (12) to fix the height position of the lower end of the lower tube (12) and constrain it to only rotate around the shaft. The upper end of the lower tube (12) abuts against the lower side wall of the head tube (11), and the upper arc surface of the lower tube (12) is completely in contact with the waist arc surface of the first welding piece (16). The other side waist of the first welding piece (16) is in contact with the front arc surface of the main beam (13), and the upper bottom edge is in contact with the middle arc surface of the head tube (11). The three form a stable front triangular welding structure under the constraint of the head tube positioning assembly (3) and the lower tube angle positioning frame (4).

4. The welding fixture for a children's balance bike according to claim 1, characterized in that: The main beam positioning assembly (5) includes a cuboid main beam positioning frame (51) fixed in the middle of the welding platform (2). The top of the main beam positioning frame (51) is provided with a circular main beam positioning hole (52) that matches the outer diameter of the end of the main beam (13). A horizontal main beam positioning plate (53) is fixed at the bottom of the main beam positioning frame (51). The front end of the arc-shaped main beam (13) is attached to the waist of the first welding piece (16), and the end is inserted into the main beam positioning hole (52). The lower end face of the main beam (13) is completely against the main beam positioning plate (53). The main beam positioning plate (53) is fixed to the welding platform (2) by bolts to ensure that the main beam (13) maintains the preset arc-shaped posture during the welding process.

5. The welding fixture for a children's balance bike according to claim 1, characterized in that: The second welding piece positioning assembly (6) includes a support block (61) fixed to the center of the rear of the welding platform (2). Two symmetrical L-shaped support grooves (62) are opened on both sides of the top of the support block (61). The bottom surface (63) of the support groove is in contact with the bottom edge of the second welding piece (17) for support. The inner side surface (64) of the support groove restricts the second welding piece (17) from moving inward. Two sets of horizontal second cylinders (65) are symmetrically arranged on both sides of the rear of the welding platform (2). Each set of second cylinders (65) is located at the second welding piece. On the outside of the connecting piece (17), the piston rod of the second cylinder (65) is connected to the positioning piece (66). The positioning piece (66) is bent to form a horizontal support edge (67) and a vertical baffle (68). The support edge (67) supports the bottom of the second welding piece (17), and the baffle (68) abuts against the outside of the second welding piece (17), restricting the second welding piece (17) from moving outward, and ensuring that the obtuse angle edge of the second welding piece (17) is fully in contact with the arc surfaces of the upper rear fork (14) and the lower rear fork (15), respectively.

6. The welding fixture for a children's balance bike according to claim 1, characterized in that: The rear upper fork positioning assembly (7) includes a third cylinder (71) located at the rear end of the welding platform (2); the rear end of the rear upper fork (14) is a straight steel pipe, and its front end is bent into a contact arc surface that fits the arc surface in the middle of the main beam (13). The contact arc surface is completely attached to both sides of the middle of the main beam (13); the third cylinder (71) is horizontally fixed at the rear end of the welding platform (2), and its piston rod is connected to two symmetrical tapered pins (72). The two tapered pins (72) are coaxially set with the corresponding rear upper fork (14). The tapered pins (72) are clearance-fitted with the round hole at the end of the rear upper fork (14). The third cylinder (71) drives the tapered pins (72) to be inserted into the end of the rear upper fork (14) synchronously, positioning the axial length and left-right symmetry of the rear upper fork (14).

7. The welding fixture for a child balance bike according to claim 1, characterized in that: The rear upper fork positioning assembly (7) also includes a fourth cylinder (73), which is vertically fixed in the middle of the welding platform (2). The piston rod of the fourth cylinder (73) is connected to a rectangular pressure block (74). The pressure block (74) acts on the rear quarter of the rear upper fork (14). The pressure block (74) has semi-circular arc grooves (75) at both ends that are adapted to the outer diameter of the rear upper fork (14). The fourth cylinder (73) drives the pressure block (74) to move downward. The arc grooves (75) completely fit the outer wall of the rear upper fork (14), restricting the vertical movement of the rear upper fork (14).

8. The welding fixture for a children's balance bike according to claim 1, characterized in that: The rear upper fork positioning assembly (7) also includes a fifth cylinder (76), which is vertically fixed above the middle of the rear upper fork (14). The piston rod of the fifth cylinder (76) is connected to a horizontal connecting plate (77). Four stainless steel spring bars (78) are fixed at the bottom of the connecting plate (77). Each rear upper fork (14) corresponds to two spring bars (78). Each spring bar (78) is arc-shaped. The two ends of the spring bar (78) abut against the upper side of the rear upper fork (14) and extend axially towards the rear upper fork (14). The fifth cylinder (76) drives the connecting plate (77) to move up and down, and corrects the welding deformation of the rear upper fork (14) through the elastic deformation of the spring bars (78).

9. A welding fixture for a child balance bike according to claim 1, characterized in that: The rear lower fork (15) is an arc-shaped steel pipe, the top of which is welded to the middle of the rear upper fork (14) and completely fits the obtuse angle side arc surface of the second welding piece (17). The end of the rear lower fork (15) abuts against the two outer sides of the main beam positioning component (5). The rear lower fork support component (8) includes a rear lower fork support block (81) fixed to the rear side of the main beam positioning component (5). The rear lower fork support block (81) acts on the rear quarter of the rear lower fork (15). The rear lower fork support block (81) has L-shaped rear lower fork support grooves (82) symmetrically opened on both sides. The lower side of the rear lower fork (15) is embedded in the rear lower fork support groove (82). The bottom surface (83) of the rear lower fork support groove supports the rear lower fork (15). The side surface (84) of the rear lower fork support groove restricts the rear lower fork (15) from moving inward, ensuring the symmetry of the two rear lower forks (15).

10. A welding fixture for a child balance bike according to claim 1, characterized in that: Two sets of frame midbody fixing components (9) are set up, located on both sides of the middle of the welding platform (2) and next to the rear lower fork (15). Each set of frame midbody fixing components (9) includes a horizontally set sixth cylinder (91). The piston rod of the sixth cylinder (91) is connected to a rectangular mounting plate (92). Three rubber pressure plates are fixed on the mounting plate (92), namely the first pressure plate (93) abutting the side of the main beam (13), the second pressure plate (94) abutting the side of the rear upper fork (14), and the third pressure plate (95) abutting the side of the rear lower fork (15). The sixth cylinder (91) drives the mounting plate (92) to move towards the frame (1). The three pressure plates simultaneously press the main beam (13), the rear upper fork (14), and the rear lower fork (15) to ensure that the three maintain their relative positions during the welding process.

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