Adjustable double tube welding table

Abstract

The application discloses an adjustable double-pipe welding table, which comprises a table top, a supporting frame, an adjusting device and a to-be-welded part positioning device, the to-be-welded part positioning device is installed on the table top, the to-be-welded part positioning device can stop and position each to-be-welded part, the table top is hingedly arranged on the supporting frame and can rotate around a horizontal rotating shaft, and the adjusting device can stop and position the table top and the supporting frame which are rotated to any angle, the to-be-welded part can be opposite to different welding directions through the rotation of the table top around the horizontal rotating shaft on the supporting frame, and the worker can accurately weld all welding positions of the part without changing the welding position around the to-be-welded part during the welding process, the to-be-welded part positioning device can accurately position the upper pipe, the lower pipe and the connecting plate in all directions, the synchronous welding of multiple parts of the cantilever can be realized at one time, the welding efficiency is high, there is no repeated positioning error, and the welding precision is high.

Description

Technical Field

[0001] This invention relates to a welding device, and more particularly to an adjustable double-tube welding table. Background Technology

[0002] Currently, electronic products often require various brackets to be mounted on walls. For cantilever brackets, the root dimension of the cantilever needs to be larger than the end dimension. To reduce the cost of cantilever brackets, they are generally made of square tubes welded together. Two symmetrically bent square tubes are overlapped and welded together at one end, and the other ends of the two square tubes form a forked support, forming a triangular support structure. In addition, a connecting plate is welded to the side wall of one end of the square tube. Currently, this type of cantilever welding involves first clamping and fixing a square tube and a connecting plate together with a clamp, and then welding the two together to form a cantilever semi-finished product. Then, this semi-finished product is clamped and positioned with another square tube, and one end of the square tube is welded together. This welding method is time-consuming, the two clamping and positioning are very inconvenient, and welding errors will occur. Moreover, during the welding process, workers have to walk around the welding table and weld in different directions, which is very inconvenient, resulting in low welding efficiency and poor welding dimensional accuracy. Summary of the Invention

[0003] To overcome the above-mentioned defects, the present invention provides an adjustable double-tube welding table. This adjustable double-tube welding table can adjust the tilt angle of the tabletop used to position the parts to be welded, which facilitates welding. It can also position multiple parts for simultaneous welding at one time, resulting in high welding accuracy.

[0004] The technical solution adopted by the present invention to solve its technical problem is: an adjustable double-tube welding table, including a tabletop, a support frame, an adjustment device, and a positioning device for parts to be welded. The positioning device for parts to be welded is installed on the tabletop and can stop and position each part to be welded. The tabletop is hinged to the support frame and can rotate around a horizontal axis. The adjustment device can stop and position the tabletop and the support frame at any angle.

[0005] As a further improvement of the present invention, the adjusting device includes a positioning gear, a meshing toothed plate, and a driving device. The positioning gear is fixedly connected to the tabletop, and the axis of the positioning gear is coaxial with the hinge axis of the tabletop and the support frame. The meshing toothed plate is provided with meshing teeth. The meshing teeth are mounted on the support frame in a linear sliding manner along the axial or radial direction of the positioning gear. The driving device can drive the meshing toothed plate to move so that the meshing teeth are inserted into the tooth groove of the positioning gear. The insertion of the meshing teeth into the tooth groove of the positioning gear can prevent the positioning gear from rotating.

[0006] As a further improvement of the present invention, the driving device includes a connecting rod, a pedal and an elastic reset member. The elastic reset member provides an elastic reset force to the meshing tooth plate in the direction of meshing and inserting with the positioning gear. One end of the connecting rod is hinged to the meshing tooth plate, and the other end of the connecting rod is hinged to the middle part of the pedal. One end of the pedal is hinged to the support frame, and the other end of the pedal forms a foot pedal for stepping.

[0007] As a further improvement of the present invention, the meshing tooth plate is T-shaped with the upper end wider than the lower end. The upper end of the meshing tooth plate has a plurality of meshing teeth that match the positioning gear, and the lower end of the meshing tooth plate has a vertical guide rod. The support frame is provided with a vertically extending guide hole. The vertical guide rod at the lower end of the meshing tooth plate is stopped in the circumferential direction and slidably inserted into the guide hole in the axial direction. The support frame is also provided with elastic element positioning grooves that are parallel to and spaced apart from the guide hole. The elastic reset member is inserted into the elastic element positioning groove. One end of the elastic reset member is tightly against the bottom surface of the elastic element positioning groove, and the other end of the elastic reset member is tightly against the step surface between the upper and lower ends of the meshing tooth plate.

[0008] As a further improvement of the present invention, the support frame has inclined limiting surfaces formed on both sides along the rotation direction of the desktop, and the lower surface of the desktop stops against the limiting surface of the support frame.

[0009] As a further improvement of the present invention, the positioning device for the parts to be welded includes an upper tube fixing device, a lower tube fixing device, and a connecting plate fixing device. The upper tube fixing device and the lower tube fixing device can fix the upper tube and the lower tube respectively and keep the welding parts of the upper tube and the lower tube in close contact. The connecting plate fixing device can stop the positioning of the connecting plate in the horizontal direction and keep the upper end of the connecting plate in close contact with the lower side wall of the upper tube.

[0010] As a further improvement of the present invention, the upper tube fixing device includes a plurality of upper tube fixing slots, an upper tube clamping device, and an upper tube stop fixedly disposed on a table. The upper tube can be accommodated in each upper tube fixing slot, and the inner sidewall of the upper tube fixing slot is in contact with the outer circumferential surface of the lower side of the upper tube. The upper tube clamping device is mounted on the table and can move up and down in a direction perpendicular to the table. The upper tube clamping device can press tightly against the outer circumferential surface of the upper side of the upper tube in the upper tube fixing slot. The upper tube stop is fixedly disposed on the table and can press tightly against the axial end face of the welding end between the upper tube and the lower tube. The lower tube fixing device includes a plurality of lower tube fixing slots, a lower tube clamping device, a lower tube left stop, and a lower tube right stop fixedly disposed on the table. The lower tube can be accommodated in each upper tube fixing slot, and the inner sidewall of the upper tube fixing slot is in contact with the outer circumferential surface of the lower side of the upper tube. Each lower tube is accommodated in a fixing slot, with the inner wall of the fixing slot fitting against the outer surface of the lower circumference of the lower tube. The lower tube clamping device is mounted on the table and can move up and down in a direction perpendicular to the table. The lower tube clamping device can press tightly against the outer circumferential surface of the upper tube in the fixing slot. The left and right lower tube stops are fixedly mounted on the table and can press tightly against the end faces of the two ends of the lower tube in the axial direction. The connecting plate fixing device includes a connecting plate insertion hole perpendicular to the table and a contact force maintaining device. The connecting plate can be inserted into the connecting plate insertion hole in a straight line in a direction perpendicular to the table. The contact force maintaining device provides the connecting plate with a holding force to keep it tightly fitted against the lower surface of one end of the upper tube.

[0011] As a further improvement of the present invention, the upper tube clamping device and the lower tube clamping device respectively include a cylinder, a pressure block and a connecting plate. The cylinder is fixed on the table, and the piston rod of the cylinder is hinged to one end of the pressure block. One end of the connecting plate is connected to the table, and the other end of the connecting plate is provided with an elongated hinge hole extending along the axial direction of the piston rod of the cylinder. The middle part of the pressure block is hinged to the elongated hinge hole through a hinge shaft, and the other end of the pressure block can press the upper surface of the upper tube and the lower tube.

[0012] As a further improvement of the present invention, the adhesion force maintaining device includes a spring, a bearing and a sliding shaft. A recessed receiving groove is formed on one side wall of the connecting plate insertion hole. The sliding shaft is slidably installed in the recessed receiving groove along the depth direction of the recessed receiving groove. The bearing is installed on the sliding shaft. The outer circumferential wall of the bearing can tightly abut against one side wall of the connecting plate located in the connecting plate insertion hole. The spring is installed in the recessed receiving groove, and both ends of the spring tightly abut against the bottom surface of the recessed receiving groove and the surface of the sliding shaft, respectively.

[0013] As a further improvement of the present invention, the desktop is further provided with a welding part limiting stop pin, a stop pin guide block, a stop pin fixing block, and a stop pin lifting drive device. The stop pin guide block is fixedly installed on the upper side of the desktop. The stop pin guide block is provided with at least one guide channel on each side of the welding part where the upper tube and the lower tube are attached. The welding part limiting stop pin can be slidably inserted into the corresponding guide channel in a direction perpendicular to the desktop. The lower end of the welding part limiting stop pin is fixedly installed on the stop pin fixing block. The stop pin fixing block stops on the lower side of the desktop. The stop pin lifting drive device drives the stop pin fixing block to move up and down in a direction perpendicular to the desktop.

[0014] The beneficial effects of this invention are: by rotating the desktop around a horizontal axis on the support frame, the different welding directions of the parts to be welded are aligned with the worker. During the welding process, the worker does not need to change the welding position around the parts to be welded to accurately weld all welding positions of the parts. The positioning device for the parts to be welded performs all-round accurate positioning of the upper pipe, lower pipe and connecting plate, and realizes simultaneous welding of multiple parts of the cantilever at one time. The welding efficiency is high, there is no repeated positioning error, and the welding accuracy is high. Attached Figure Description

[0015] Figure 1 This is a first perspective view of the present invention;

[0016] Figure 2 Bit Figure 1 Enlarged view of section A in the middle;

[0017] Figure 3 This is a second perspective view of the present invention;

[0018] Figure 4 for Figure 3 Enlarged view of section B in the middle;

[0019] Figure 5 This is the front view of the present invention;

[0020] Figure 6 for Figure 5 C-axis sectional view;

[0021] Figure 7 A cross-sectional view of the positioning gear in the disengaged state of the meshing gear;

[0022] Figure 8 Cross-sectional view of the desktop before engagement, when it is in the positive limit position;

[0023] Figure 9 This is a cross-sectional view of the desktop after it has been rotated to the positive limit position and engaged.

[0024] Figure 10 Cross-sectional view of the desktop before engagement when it is in the reverse limit position;

[0025] Figure 11Cross-sectional view of the desktop after it has been rotated to the reverse limit position and engaged;

[0026] Figure 12 This is a diagram showing the positioning state of the lower tube in this invention;

[0027] Figure 13 for Figure 12 Sectional view along the middle-DD direction;

[0028] Figure 14 This invention provides a state diagram of the positioning of the lower pipe, upper pipe, and connecting plate;

[0029] Figure 15 for Figure 14 Enlarged view of section F in the middle;

[0030] Figure 16 for Figure 14 EE-directed sectional view;

[0031] Figure 17 for Figure 16 Enlarged view of section G in the middle;

[0032] Figure 18 An exploded view of the structural principle of the adhesion retention device;

[0033] Figure 19 A perspective view of the present invention in a horizontal welding state;

[0034] Figure 20 A perspective view of the invention in its inner welding state;

[0035] Figure 21 A perspective view of the invention in the external welding state. Detailed Implementation

[0036] Example: An adjustable double-tube welding table includes a tabletop 1, a support frame 2, an adjustment device, and a positioning device for parts to be welded. The positioning device for parts to be welded is installed on the tabletop 1 and can stop and position each part to be welded. The tabletop 1 is hinged to the support frame 2 and can rotate around a horizontal axis 5. The adjustment device can stop and position the tabletop 1 and the support frame 2 at any angle.

[0037] When welding the parts of the cantilever, the upper tube, lower tube, and connecting plate of the cantilever are fully positioned by the part positioning device, so that the upper tube and lower tube are axially aligned and tightly fitted together, and the upper tube and connecting plate are tightly fitted together. Then, the table 1 is rotated to a suitable angle by the adjustment device, and one side of each positioned part is welded. Then, the table 1 is rotated to another suitable angle by the adjustment device, and the other side of each positioned part is welded. After the parts are welded, the welded assembly can be removed from the part positioning device. This device allows workers to perform omnidirectional welding of multiple sides of the assembly from one position, without the need for workers to move around the workpiece. Moreover, all parts of the cantilever can be welded into a finished assembly in one positioning, which greatly improves welding efficiency and welding quality.

[0038] The adjustment device includes a positioning gear 3, a meshing toothed plate 4, and a driving device. The positioning gear 3 is fixedly connected to the tabletop 1, and the axis of the positioning gear 3 is coaxial with the hinge axis between the tabletop 1 and the support frame 2. The meshing toothed plate 4 is provided with meshing teeth 6. The meshing teeth 6 can be linearly slidably mounted on the support frame 2 along the axial or radial direction of the positioning gear 3. The driving device can drive the meshing toothed plate 4 to move so that the meshing teeth 6 are inserted into the tooth groove of the positioning gear 3. The meshing teeth 6 inserted into the tooth groove of the positioning gear 3 can prevent the positioning gear 3 from rotating.

[0039] First, the meshing toothed plate 4 is disengaged from the positioning gear 3 by driving the device. The tabletop 1 is rotated until the meshing toothed plate 4 and the positioning gear 3 are disengaged. The meshing toothed plate 4 slides so that the meshing teeth 6 on it are engaged or disengaged from the tooth grooves on the positioning gear 3. This achieves the adjustment of preventing the positioning gear 3 from rotating or allowing the positioning gear 3 to rotate freely. The meshing toothed plate 4 can slide radially along the positioning gear 3 to achieve the engagement and positioning of the meshing teeth 6 and the positioning gear 3, or it can slide to achieve the engagement and positioning of the meshing teeth 6 and the positioning gear 3. Adjustment can be made according to design requirements. In addition to the structure of positioning the tabletop 1 by meshing the positioning gear 3 and the meshing toothed plate 4, a clamping plate can be used to clamp the hinged connection between the tabletop 1 and the support frame 2 to achieve the positioning of the tabletop 1. Alternatively, a coaxial friction wheel can be set on the lower side of the tabletop 1, and a brake pad can be set on the support frame 2. The positioning of the tabletop 1 can be achieved by the brake pad being in close contact or disengaging from the friction wheel. These are equivalent replacement structures that can be easily conceived by those skilled in the art based on this application and are within the scope of protection of this application.

[0040] The driving device includes a connecting rod 7, a pedal 8, and an elastic reset member 9. The elastic reset member 9 provides an elastic reset force to the meshing gear 4 in the direction of meshing and engaging with the positioning gear 3. One end of the connecting rod 7 is hinged to the meshing gear 4, and the other end is hinged to the middle part of the pedal 8. One end of the pedal 8 is hinged to the support frame 2, and the other end forms a foot pedal for stepping. By stepping on the pedal 8, it rotates around its hinge axis, thereby driving the connecting rod 7 to slide up and down, which in turn drives the meshing gear 4 to slide radially along the positioning gear 3, realizing the engagement or disengagement of the positioning gear 3. This structure is simple, easy to operate, and more efficient with hand and foot coordination. Alternatively, other structures can be used, such as a handwheel and screw nut mechanism, etc.

[0041] The meshing toothed plate 4 has a T-shaped structure with a width at the upper end greater than that at the lower end. The upper end of the meshing toothed plate 4 has several meshing teeth 6 that match the positioning gear 3. The lower end of the meshing toothed plate 4 forms a vertical guide rod. The support frame 2 has vertically extending guide holes. The vertical guide rod at the lower end of the meshing toothed plate 4 is circumferentially stopped but axially slidable within the guide holes. The support frame 2 also has elastic positioning grooves spaced parallel to the guide holes. The elastic reset member 9 is inserted into the elastic positioning groove, with one end of the elastic reset member 9 abutting the bottom surface of the elastic positioning groove and the other end abutting the stepped surface between the upper and lower ends of the meshing toothed plate 4. The elastic reset member 9 ensures that after the worker releases the pedal 8, the meshing toothed plate 4 automatically engages and positions with the positioning gear 3, making operation more convenient.

[0042] The support frame 2 has inclined limiting surfaces 10 on both sides along the rotation direction of the desktop 1, and the lower surface of the desktop 1 stops against the limiting surface 10 of the support frame 2. The limiting surface 10 limits the rotation range of the desktop 1, preventing collision damage to parts due to excessive rotation.

[0043] The positioning device for the parts to be welded includes an upper tube fixing device, a lower tube fixing device, and a connecting plate fixing device. The upper tube fixing device and the lower tube fixing device can fix the upper tube 31 and the lower tube 32 respectively and keep the welding parts of the upper tube 31 and the lower tube 32 in close contact. The connecting plate fixing device can stop and position the connecting plate 33 in the horizontal direction and keep the upper end of the connecting plate 33 in close contact with the lower side wall of the upper tube.

[0044] The upper tube fixing device includes several upper tube fixing slots 11, an upper tube clamping device 12, and an upper tube stop 14 fixedly mounted on the tabletop 1. The upper tube can be accommodated in each upper tube fixing slot 11, and the inner wall of the upper tube fixing slot 11 is attached to the outer circumferential surface of the lower side of the upper tube. The upper tube clamping device 12 is mounted on the tabletop 1 and can move up and down in a direction perpendicular to the tabletop 1. The upper tube clamping device 12 can press tightly against the outer circumferential surface of the upper side of the upper tube in the upper tube fixing slot 11. The upper tube stop 14 is fixedly mounted on the tabletop 1 and can press tightly against the axial end face of the welding end between the upper tube and the lower tube. The lower tube fixing device includes several lower tube fixing slots 15, a lower tube clamping device 16, a lower tube left stop 17, and a lower tube right stop 18 fixedly mounted on the tabletop 1. The lower tube can be accommodated in... Each lower tube fixing slot 15 is fitted with the inner wall of the lower tube fixing slot 15 and the outer surface of the lower circumference of the lower tube. The lower tube clamping device 16 is installed on the table 1 and can move up and down in a direction perpendicular to the table 1. The lower tube clamping device 16 can press tightly against the outer circumferential surface of the upper side of the lower tube in the lower tube fixing slot 15. The lower tube left stop 17 and the lower tube right stop 18 are fixedly installed on the table 1 and can press tightly against the end faces of the two ends of the lower tube in the axial direction. The connecting plate fixing device includes a connecting plate insertion hole 19 perpendicular to the table 1 and a contact force holding device. The connecting plate can be inserted into the connecting plate insertion hole 19 in a straight line in a direction perpendicular to the table 1. The contact force holding device provides the connecting plate with a holding force to keep it tightly in contact with the lower surface of one end of the upper tube.

[0045] The above-mentioned device achieves full positioning of the upper tube, lower tube, and connecting plate. At the end where the upper tube and lower tube are welded together, an upper tube clamping device 12 can be used to clamp the upper tube and lower tube simultaneously and ensure that the upper tube and lower tube are tightly fitted. The above structure is simple and can fully position the upper tube, lower tube, and connecting plate. Alternatively, a groove matching the upper tube and lower tube can be set on the table 1, and a negative pressure air passage or magnetic attraction device can be set on the bottom surface of the groove to achieve positioning of the upper tube, lower tube, and connecting plate. This is an equivalent replacement structure that is easy for a person skilled in the art to think of when seeing the structure of this patent.

[0046] The upper tube clamping device 12 and the lower tube clamping device 16 each include a cylinder 20, a pressure block 21, and a connecting piece 22. The cylinder 20 is fixed to the tabletop 1. The piston rod of the cylinder 20 is hinged to one end of the pressure block 21. One end of the connecting piece 22 is connected to the tabletop 1, and the other end of the connecting piece 22 has an elongated hinge hole extending axially along the piston rod of the cylinder 20. The middle part of the pressure block 21 is slidably hinged to the elongated hinge hole via a hinge shaft. The other end of the pressure block 21 can clamp the upper surface of the upper and lower tubes. This clamping device structure allows the pressure block 21 to be lifted to a certain height when opened, and then flipped over to completely detach from the upper and lower tubes, facilitating quick removal of the upper and lower tubes and avoiding interference.

[0047] The contact force maintaining device includes a spring 23, a bearing 24, and a sliding shaft 25. A recessed receiving groove 26 is formed on one side wall of the connecting plate insertion hole 19. The sliding shaft 25 is slidably installed in the recessed receiving groove 26 along its depth direction. The bearing 24 is installed on the sliding shaft 25, and its outer circumferential outer wall can tightly abut against the side wall of the connecting plate located in the connecting plate insertion hole 19. The spring 23 is installed in the recessed receiving groove 26, and its two ends respectively abut against the bottom surface of the recessed receiving groove 26 and the surface of the sliding shaft 25. The spring 23 ensures that the outer ring of the bearing 24 is always tightly fitted with the side wall of the connecting plate. The bearing 24 and the connecting plate are in rolling contact, which will not damage the side wall of the connecting plate.

[0048] The desktop 1 is also provided with a welding part limiting stop pin 27, a stop pin guide block 28, a stop pin fixing block 29, and a stop pin lifting drive device 30. The stop pin guide block 28 is fixedly installed on the upper side of the desktop 1. The stop pin guide block 28 is provided with at least one guide channel on each side of the welding part where the upper tube and the lower tube are attached. The welding part limiting stop pin 27 can be slidably inserted into the corresponding guide channel in a direction perpendicular to the desktop 1. The lower end of the welding part limiting stop pin 27 is fixedly installed on the stop pin fixing block 29. The stop pin fixing block 29 stops on the lower side of the desktop 1. The stop pin lifting drive device 30 drives the stop pin fixing block 29 to move up and down in a direction perpendicular to the desktop 1.

[0049] The upper and lower pipes are limited by a lifting and lowering welding part limiting pin 27 to ensure perfect alignment of the upper and lower pipes. After the upper pipe pressing device 12 presses one end of the upper pipe, the welding part limiting pin descends and disengages from the welding part of the upper and lower pipes to avoid obstructing the welding part and affecting the welding effect.

Claims

1. An adjustable double-tube welding table, characterized in that: The system includes a desktop (1), a support frame (2), an adjustment device, and a positioning device for the parts to be welded. The positioning device for the parts to be welded is installed on the desktop and can stop and position each part to be welded. The desktop is hinged to the support frame and can rotate around a horizontal axis (5). The adjustment device can stop and position the desktop and the support frame at any angle. The desktop is also provided with a welding part limiting stop pin (27), a stop pin guide block (28), a stop pin fixing block (29), and a stop pin lifting drive device (30). The stop pin guide block is fixedly installed on the upper side of the desktop. The stop pin guide block is provided with at least one guide channel on each side of the welding part where the upper and lower tubes are attached. The stop pin can be slidably inserted into the corresponding guide channel in a direction perpendicular to the tabletop. The lower end of the welding part limiting stop pin is fixedly installed on the stop pin fixing block. The stop pin fixing block stops on the lower side of the tabletop. The stop pin lifting drive device drives the stop pin fixing block to move up and down in a direction perpendicular to the tabletop. The upper tube, lower tube and connecting plate of the cantilever are positioned by the part positioning device to be welded, so that the upper tube and lower tube are axially aligned and keep the upper tube and lower tube tightly fitted. The upper tube and connecting plate are tightly fitted. The tabletop is rotated to a suitable angle by the adjustment device, and one side of each part after positioning is welded. Then the tabletop is rotated to another suitable angle by the adjustment device, and the other side of each part after positioning is welded. The positioning device for the parts to be welded includes an upper tube fixing device, a lower tube fixing device, and a connecting plate fixing device. The upper tube fixing device and the lower tube fixing device can fix the upper tube (31) and the lower tube (32) respectively and keep the welding parts of the upper tube and the lower tube tightly fitted. The connecting plate fixing device can stop and position the connecting plate (33) in the horizontal direction and keep the upper end of the connecting plate tightly fitted with the lower side wall of the upper tube. The upper tube fixing device includes several upper tube fixing slots (11) fixed on the table, an upper tube clamping device (12), and an upper tube stop (14). The upper tube can be accommodated in each upper tube fixing slot. The upper tube is fixed in the slot, and the inner wall of the upper tube fixing slot is attached to the outer surface of the lower circumference of the upper tube. The upper tube clamping device is installed on the table in a direction perpendicular to the table. The upper tube clamping device can press against the outer circumference of the upper tube in the upper tube fixing slot. The upper tube stop is fixedly installed on the table. The upper tube stop can press against the axial end face of the welding end of the upper tube and the lower tube. The lower tube fixing device includes several lower tube fixing slots (15), a lower tube clamping device (16), a lower tube left stop (17), and a lower tube right stop (18) fixedly installed on the table. The lower tube can be accommodated in each lower tube fixing slot. The lower tube is fixed in the slot, and the inner wall of the slot is attached to the outer surface of the lower circumference of the lower tube. The lower tube clamping device is installed on the table and can move up and down in a direction perpendicular to the table. The lower tube clamping device can press against the outer circumference of the upper side of the lower tube in the slot. The left and right stops of the lower tube are fixedly installed on the table. The left and right stops of the lower tube can press against the end faces of the two ends of the lower tube in the axial direction. The connecting plate fixing device includes a connecting plate insertion hole (19) perpendicular to the table and a contact force holding device. The connecting plate can be inserted into the connecting plate in a straight line in a direction perpendicular to the table. Inside the insertion hole, the contact force holding device provides the connecting plate with a holding force to keep it tightly in contact with the lower surface of one end of the upper tube. The contact force holding device includes a spring (23), a bearing (24), and a sliding shaft (25). A recessed receiving groove (26) is formed on one side wall of the insertion hole of the connecting plate. The sliding shaft is installed in the recessed receiving groove and can slide along the depth direction of the recessed receiving groove. The bearing is installed on the sliding shaft and the outer circumferential wall of the bearing can press against the side wall of the connecting plate located in the insertion hole of the connecting plate. The spring is installed in the recessed receiving groove and the two ends of the spring press against the bottom surface of the recessed receiving groove and the surface of the sliding shaft, respectively.

2. The adjustable double-tube welding table according to claim 1, characterized in that: The adjustment device includes a positioning gear (3), a meshing toothed plate (4), and a driving device. The positioning gear is fixedly connected to the tabletop, and the axis of the positioning gear is coaxial with the hinge axis of the tabletop and the support frame. The meshing toothed plate is provided with meshing teeth (6). The meshing teeth can be installed on the support frame in a linear sliding manner along the axial or radial direction of the positioning gear. The driving device can drive the meshing toothed plate to move so that the meshing teeth are inserted into the tooth groove of the positioning gear. The meshing teeth inserted into the tooth groove of the positioning gear can prevent the positioning gear from rotating.

3. The adjustable double-tube welding table according to claim 2, characterized in that: The driving device includes a connecting rod (7), a pedal (8), and an elastic reset member (9). The elastic reset member provides the meshing tooth plate with an elastic reset force to move in the direction of meshing and inserting with the positioning gear. One end of the connecting rod is hinged to the meshing tooth plate, and the other end of the connecting rod is hinged to the middle part of the pedal. One end of the pedal is hinged to the support frame, and the other end of the pedal forms a foot pedal for stepping.

4. The adjustable double-tube welding table according to claim 3, characterized in that: The meshing gear plate has a T-shaped structure with a width at the upper end greater than that at the lower end. The upper end of the meshing gear plate has several meshing teeth that match the positioning gear, and the lower end of the meshing gear plate has a vertical guide rod. The support frame has a vertically extending guide hole. The vertical guide rod at the lower end of the meshing gear plate is circumferentially stopped and axially slidably inserted into the guide hole. The support frame also has elastic element positioning grooves that are parallel to and spaced apart from the guide hole. The elastic reset element is inserted into the elastic element positioning groove. One end of the elastic reset element is tightly pressed against the bottom surface of the elastic element positioning groove, and the other end of the elastic reset element is tightly pressed against the step surface between the upper and lower ends of the meshing gear plate.

5. The adjustable double-tube welding table according to claim 1, characterized in that: The support frame has inclined limiting surfaces (10) on both sides along the rotation direction of the desktop, and the lower surface of the desktop stops against the limiting surface of the support frame.

6. The adjustable double-tube welding table according to claim 1, characterized in that: The upper tube clamping device and the lower tube clamping device respectively include a cylinder (20), a pressure block (21) and a connecting piece (22). The cylinder is fixed on the table. The piston rod of the cylinder is hinged to one end of the pressure block. One end of the connecting piece is connected to the table. The other end of the connecting piece is provided with a long strip-shaped hinge hole extending along the axial direction of the piston rod of the cylinder. The middle part of the pressure block is hinged to the long strip-shaped hinge hole through a hinge shaft. The other end of the pressure block can press the upper surface of the upper tube and the lower tube.

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