Tower crane jib angle-adjustable welding tool

Abstract

The utility model relates to a kind of tower crane lifting arm adjustable angle welding tool, it solves the technical problem of how to improve the high welding assembly efficiency of tower crane lifting arm, it includes horizontal direction base, vertical direction support, fixed mechanism, first axial positioning mechanism, second axial positioning mechanism, first lifting device, third lifting device, multiple limiting devices and multiple width direction limiting mechanism, vertical direction support is fixedly connected in the front end of horizontal direction base, and fixed mechanism is fixedly connected with the top of vertical direction support.

Description

Technical Field

[0001] This utility model relates to the field of tower crane technology, and more specifically, to a welding fixture for an adjustable angle tower crane boom. Background Technology

[0002] A tower crane is a type of crane used for vertical and horizontal material transport. The main structure of a tower crane consists of the following parts: base, tower body, slewing platform, operator's cab, counterweight boom, lifting boom, and hoisting mechanism. The tower body is a vertical steel structure, typically composed of multiple standard sections, and its height can be adjusted via bolt connections. The slewing platform is located at the upper part of the tower body, allowing the boom to rotate horizontally around the center of the tower body. The operator's cab is mounted on the slewing platform. The lifting boom is responsible for the actual lifting operation and is composed of multiple boom sections connected together. The counterweight boom is used to install counterweights to balance the torque generated by the lifting boom when lifting heavy objects. The hoisting mechanism, driven by a motor and a reducer, rotates the drum to wind or release the wire rope, thus lifting or lowering the goods. References can be made to invention patent applications CN119160803A and CN118718620A, which disclose a tower crane structure. Utility model patent CN219058361U discloses a tower body structure.

[0003] A crane boom consists of multiple boom sections connected end to end. In the tower crane manufacturing process, these boom sections are assembled by welding. Improving welding and assembly efficiency and reducing production costs are technical problems that urgently need to be solved by those skilled in the art. Summary of the Invention

[0004] This utility model aims to solve the technical problem of how to improve the high welding and assembly efficiency of tower crane booms, and provides an adjustable angle welding fixture for tower crane booms that improves welding and assembly efficiency and can also adjust the angle between boom sections.

[0005] This utility model provides an adjustable angle welding fixture for tower crane booms, including a horizontal base, a vertical support, a fixing mechanism, a first axial positioning mechanism, a second axial positioning mechanism, a first lifting device, a third lifting device, multiple limiting devices, and multiple width-direction limiting mechanisms. The vertical support is fixedly connected to the front end of the horizontal base, and the fixing mechanism is fixedly connected to the top of the vertical support. The first axial positioning mechanism includes a first handwheel, a first lead screw, a first telescopic plate, a first nut, a first telescopic shaft, a second telescopic shaft, and a first positioning plate. The first lead screw is rotatably connected to the bottom of the vertical support, the first handwheel is connected to the end of the first lead screw, the first nut is connected to the first lead screw, and the first telescopic shaft... The retractable plate is fixedly connected to the first nut. The first and second telescopic shafts pass through the bottom of the vertical support and can slide. The first positioning plate is fixedly connected to the ends of the first and second telescopic shafts. The second axial positioning mechanism includes a second handwheel, a second lead screw, a second telescopic plate, a second nut, a third telescopic shaft, a fourth telescopic shaft, and a second positioning plate. The second lead screw is rotatably connected to the bottom of the vertical support. The second handwheel is fixedly connected to the end of the second lead screw. The second nut is connected to the second lead screw. The second telescopic plate is fixedly connected to the second nut. The third and fourth telescopic shafts pass through the bottom of the vertical support and can slide. The second positioning plate is fixedly connected to the ends of the third and fourth telescopic shafts.

[0006] Preferably, the limiting device includes a clamping plate connecting beam, a left clamping plate, a right clamping plate, a left fixing block, and a right fixing block. The left fixing block is fixedly connected to the left end of the clamping plate connecting beam, and the right fixing block is fixedly connected to the right end of the clamping plate connecting beam. The left clamping plate is detachably connected to the left fixing block, and the right clamping plate is detachably connected to the right fixing block. The left clamping plate is provided with a vertical side guard and a horizontal side guard, and the right clamping plate is provided with a vertical side guard and a horizontal side guard. The left fixing block is provided with a platform, and the right fixing block is provided with a platform. The clamping plate connecting beam is fixedly connected to a horizontal base. Multiple limiting devices are arranged side by side along the width direction of the horizontal base, and the first limiting device among the multiple limiting devices is close to the second axial positioning mechanism and the first axial positioning mechanism.

[0007] The width-direction limiting mechanism includes a straight plate mounting beam, a left connecting block, a left straight plate, a right connecting block, and a right straight plate. The left connecting block is fixedly connected to the left end of the straight plate mounting beam, and the right connecting block is fixedly connected to the right end of the straight plate mounting beam. The left straight plate is detachably connected to the left connecting block, and the right straight plate is detachably connected to the right connecting block. The left connecting block has a platform, and the right connecting block has a platform. The straight plate mounting beam is fixedly connected to the horizontal base. Multiple width-direction limiting mechanisms are arranged side by side along the width direction of the horizontal base.

[0008] Multiple width-direction limiting mechanisms are located at the rear part of the horizontal base, multiple limiting devices are located at the front part of the horizontal base, and the first width-direction limiting mechanism among the multiple width-direction limiting mechanisms is located behind the last limiting device among the multiple limiting devices.

[0009] The first lifting device includes a crossbar, a left manual screw jack, and a right manual screw jack. The left end of the crossbar is connected to the output end of the left manual screw jack, and the right end of the crossbar is connected to the output end of the right manual screw jack. The crossbar is located above the horizontal base, and the left and right manual screw jacks are located on both sides of the horizontal base. The first lifting device is located between the last limiting device among multiple limiting devices and the first width-direction limiting mechanism among multiple width-direction limiting mechanisms.

[0010] The third lifting device includes a crossbar, a left-side manual screw jack, and a right-side manual screw jack;

[0011] The third lifting device is located between the last two of the multiple width-direction limiting mechanisms.

[0012] Preferably, the plurality of limiting devices are a first limiting device, a second limiting device, a third limiting device, and a fourth limiting device, and the plurality of width-direction limiting mechanisms are a first width-direction limiting mechanism, a second width-direction limiting mechanism, a third width-direction limiting mechanism, a fourth width-direction limiting mechanism, and a fifth width-direction limiting mechanism.

[0013] Preferably, the left fixing block is provided with a pad placement groove, and the right fixing block is provided with a pad placement groove; the left connecting block is provided with a pad groove, and the right connecting block is provided with a pad groove.

[0014] Preferably, the fixing mechanism is a positioning lug on the upper chord.

[0015] The advantages of this invention are that the welding and assembly process is highly efficient and easy to operate. It enables the boom section at the end of the lifting arm to tilt upwards, thereby increasing strength during operation, enhancing load-bearing capacity, and improving operational safety.

[0016] Further features and aspects of this invention will be clearly described in the following detailed description with reference to the accompanying drawings. Attached Figure Description

[0017] Figure 1 It is an isometric drawing of the adjustable angle welding fixture for tower crane boom;

[0018] Figure 2 yes Figure 1 The image shows the front view of the adjustable angle welding fixture for the tower crane boom.

[0019] Figure 3 yes Figure 1 The rear view of the adjustable angle welding fixture for the tower crane boom shown.

[0020] Figure 4 yes Figure 1 The top view of the adjustable angle welding fixture for the tower crane boom shown.

[0021] Figure 5 yes Figure 1 The left view of the adjustable angle welding fixture for the tower crane boom shown.

[0022] Figure 6 This is an isometric view of the adjustable angle welding fixture for tower crane boom from another perspective;

[0023] Figure 7 yes Figure 1 The diagram shows the structural positions of the two sets of axial positioning mechanisms containing handwheels.

[0024] Figure 8 yes Figure 2 The diagram shows the structural positions of the two sets of axial positioning mechanisms.

[0025] Figure 9 yes Figure 4 The diagram shows the structural positions of the two sets of axial positioning mechanisms.

[0026] Figure 10 This is a structural diagram showing two sets of axial positioning mechanisms installed at the bottom of a vertical support.

[0027] Figure 11 This is a structural diagram showing the connection between the left side plate and the left fixing block;

[0028] Figure 12 yes Figure 1 The diagram shows the structure of the first lifting device.

[0029] Figure 13 This is a schematic diagram of the first and second arm sections being welded and assembled on the tooling;

[0030] Figure 14 yes Figure 13 The front view of the structure shown;

[0031] Figure 15 yes Figure 14 A magnified view of a section at point M;

[0032] Figure 16 yes Figure 14 A magnified view of a portion of point N in the middle;

[0033] Figure 17 yes Figure 13 A schematic diagram of the structure in which two axial positioning mechanisms are used to axially position the second arm section.

[0034] Explanation of symbols in the diagram:

[0035] 1. Horizontal base, 2. Vertical support, 2-1. Bottom, 3. Upper chord positioning ear plate, 4. First handwheel, 5. First lead screw, 6. First telescopic plate, 7. First nut, 8. First telescopic shaft, 9. Second telescopic shaft, 10. First positioning plate, 11. Second handwheel, 12. Second lead screw, 13. Second nut, 14. Third telescopic shaft, 15. Fourth telescopic shaft, 16. Second positioning plate, 17a. First limiting device, 17. Clamping plate connecting beam, 18. Left clamping plate, 18-1. Vertical side guard, 18-2. Horizontal side guard, 19. Right clamping plate, 20. Left fixing block, 20-1. Platform, 20-2. Pad placement slot, 21. Right fixing block, 17b. Second limiting device, 17c. Third limiting device, 17d. Fourth limiting device; 22a. First width direction limiting mechanism, 22. Straight plate mounting beam, 23. Left connecting block, 23-1. Platform, 23-2. Pad slot, 24. Left straight plate, 25. Right connecting block, 26. Right straight plate, 22b. Second width direction limiting mechanism, 22c. Third width direction limiting mechanism, 22d. Fourth width direction limiting mechanism, 22e. Fifth width direction limiting mechanism; 27a. First lifting device, 27. Crossbar, 28. Left manual screw jack, 29. Right manual screw jack, 27b. Second lifting device, 27c. Third lifting device; 28. First boom section, 28-1. Upper chord, 29. Second boom section, 29-1. Upper chord. Detailed Implementation

[0036] The application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0037] The specific embodiments described below are merely preferred embodiments of this application, and the scope of protection of this application is not limited thereto. Those skilled in the art can make modifications or variations based on the principles, concepts, and spirit of this application, and the resulting technical solutions should all be covered within the scope of protection of this application.

[0038] like Figure 1-12As shown, the adjustable angle welding fixture for the tower crane boom includes a horizontal base 1, a vertical support 2, an upper chord positioning lug 3, a first axial positioning mechanism, a second axial positioning mechanism, a first limiting device 17a, a second limiting device 17b, a third limiting device 17c, a fourth limiting device 17d, a first width limiting mechanism 22a, a second width limiting mechanism 22b, a third width limiting mechanism 22c, a fourth width limiting mechanism 22d, a fifth width limiting mechanism 22e, a first lifting device 27a, a second lifting device 27b, and a third lifting device 27c. The vertical support 2 is fixedly installed at the front end of the horizontal base 1. The upper chord positioning ear plate 3 is fixedly connected to the top of the vertical support 2. The first axial positioning mechanism includes a first handwheel 4, a first lead screw 5, a first telescopic plate 6, a first nut 7, a first telescopic shaft 8, a second telescopic shaft 9, and a first positioning plate 10. The first lead screw 5 is rotatably connected to the bottom 2-1 of the vertical support 2. The first handwheel 4 is connected to the end of the first lead screw 5. The first nut 7 is connected and engaged with the first lead screw 5. The first telescopic plate 6 is fixedly connected to the first nut 7. The first telescopic shaft 8 and the second telescopic shaft 9 pass through the bottom 2-1 of the vertical support 2 and can slide. The first positioning plate 10 is fixedly connected to the end of the first telescopic shaft 8 and the end of the second telescopic shaft 9. The second axial positioning mechanism has the same structure as the first axial positioning mechanism. The second axial positioning mechanism includes a second handwheel 11, a second lead screw 12, a second telescopic plate, a second nut 13, a third telescopic shaft 14, a fourth telescopic shaft 15, and a second positioning plate 16. The second lead screw 12 is rotatably connected to the bottom 2-1 of the vertical support 2. The second handwheel 11 is fixedly connected to the end of the second lead screw 12. The second nut 13 is connected and engaged with the second lead screw 12. The second telescopic plate is fixedly connected to the second nut 13. The third telescopic shaft 14 and the fourth telescopic shaft 15 pass through the bottom 2-1 of the vertical support 2 and can slide. The second positioning plate 16 is fixedly connected to the end of the third telescopic shaft 14 and the end of the fourth telescopic shaft 15.

[0039] The first limiting device 17a includes a plate connecting beam 17, a left plate 18, a right plate 19, a left fixing block 20, and a right fixing block 21. The left fixing block 20 is fixedly connected to the left end of the plate connecting beam 17, and the right fixing block 21 is fixedly connected to the right end of the plate connecting beam 17. The left plate 18 is detachably connected to the left fixing block 20, and the right plate 19 is detachably connected to the right fixing block 21. The left plate 18 has a vertical side guard 18-1 and a horizontal side guard 18-2. The right plate 19 has the same structure as the left plate 18, and also has a vertical side guard and a horizontal side guard. The left fixing block 20 has a platform 20-1 and a pad placement groove 20-2. The right fixing block 21 has the same structure as the left fixing block 20, and also has a platform and a pad placement groove. The pad placement groove 20-2 is a preferred design. The plate connecting beam 17 is fixedly installed on the horizontal base 1.

[0040] The structure of the second limiting device 17b is the same as that of the first limiting device 17a, the structure of the third limiting device 17c is the same as that of the first limiting device 17a, and the structure of the fourth limiting device 17d is the same as that of the first limiting device 17a. The clamping plate connecting beams of the second limiting device 17b, the third limiting device 17c, and the fourth limiting device 17d are all fixedly installed on the horizontal base 1. The first limiting device 17a is located near the second axial positioning mechanism and the first axial positioning mechanism. The four sets of limiting devices are arranged side-by-side along the width direction of the horizontal base 1.

[0041] The first width-direction limiting mechanism 22a includes a straight plate mounting beam 22, a left connecting block 23, a left straight plate 24, a right connecting block 25, and a right straight plate 26. The left connecting block 23 is fixedly connected to the left end of the straight plate mounting beam 22, and the right connecting block 25 is fixedly connected to the right end of the straight plate mounting beam 22. The left straight plate 24 is detachably connected to the left connecting block 23, and the right straight plate 26 is detachably connected to the right connecting block 25. The left connecting block 23 is provided with a platform 23-1 and a pad groove 23-2, with the pad groove 23-2 being a preferred design. The right connecting block 25 is also provided with a platform and a pad groove. The straight plate mounting beam 22 is fixedly mounted on the horizontal base 1.

[0042] The structures of the second width-direction limiting mechanism 22b, the third width-direction limiting mechanism 22c, the fourth width-direction limiting mechanism 22d, and the fifth width-direction limiting mechanism 22e are all the same as those of the first width-direction limiting mechanism 22a. The second width-direction limiting mechanism 22b, the third width-direction limiting mechanism 22c, the fourth width-direction limiting mechanism 22d, and the fifth width-direction limiting mechanism 22e are all fixedly installed on the horizontal base 1. The five sets of width-direction limiting mechanisms are arranged side-by-side along the width direction of the horizontal base 1.

[0043] The first width-direction limiting mechanism 22a is located behind the fourth limiting device 17d, meaning that all five width-direction limiting mechanisms are located at the rear of the horizontal base 1. The first limiting device 17a, the second limiting device 17b, the third limiting device 17c, and the fourth limiting device 17d are located at the front of the horizontal base 1.

[0044] The first lifting device 27a includes a crossbar 27, a left manual screw jack 28, and a right manual screw jack 29. The left and right manual screw jacks 28 and 29 are common products in the prior art. The left end of the crossbar 27 is connected to the output end of the left manual screw jack 28, and the right end of the crossbar 27 is connected to the output end of the right manual screw jack 29. The crossbar 27 is located above the horizontal base 1, and the left and right manual screw jacks 28 and 29 are located on opposite sides of the horizontal base 1. The left and right manual screw jacks 28 and 29 are equipped with operating handwheels. When the operator rotates the two handwheels, the output ends of the left and right manual screw jacks 28 and 29 rise or fall, thereby raising or lowering the crossbar 27.

[0045] The first lifting device 27a is located between the fourth limiting device 17d and the first width direction limiting mechanism 22a.

[0046] The structure of the second lifting device 27b is the same as that of the first lifting device 27a, and the structure of the third lifting device 27c is the same as that of the first lifting device 27a.

[0047] The second lifting device 27b is located between the third width-direction limiting mechanism 22c and the fourth width-direction limiting mechanism 22d. The third lifting device 27c is located between the fourth width-direction limiting mechanism 22d and the fifth width-direction limiting mechanism 22e.

[0048] The following describes the process of welding the boom sections using the aforementioned adjustable angle welding fixture for tower crane booms:

[0049] refer to Figure 13-17The first step is to prepare two modules: the first boom section 28 and the second boom section 29. The first boom section 28 is the end boom section of the entire crane boom.

[0050] The second step involves placing the second arm section 29 on the horizontal base 1. The foremost position of the bottom of the second arm section 29 presses against the platforms 20-1 of the left fixing block 20 and 21 of the right fixing block in the first limiting device 17a. The rearmost position of the bottom of the second arm section 29 presses against the platforms of the left and right fixing blocks in the fourth limiting device 17d. The middle part of the bottom of the second arm section 29 presses against the platforms of the left and right fixing blocks in the second limiting device 17b. The middle part of the bottom of the second arm section 29 presses against the platforms of the left and right fixing blocks in the third limiting device 17c. In other words, the left and right fixing blocks of the four sets of limiting devices support the entire second arm section 29. The operator operates the handwheel to adjust the first axial positioning mechanism and the second axial positioning mechanism, and adjusts the positions of the first positioning plate 10 and the second positioning plate 16 so that the first positioning plate 10 and the second positioning plate 16 are located in the same vertical plane.

[0051] The third step is to place the front end face of the bottom of the second arm section 29 against the first positioning plate 10 and the second positioning plate 16 to achieve the positioning of the second arm section 29 in the axial direction, that is, the positioning along the length of the horizontal base 1.

[0052] Fourth step: Using the first limiting device 17a, the left clamping plate 18 is fixedly connected to the left fixing block 20 with bolts, so that the vertical side flange 18-1 of the left clamping plate 18 is attached to the left end face of the bottom of the second boom section 29, and the horizontal side flange 18-2 of the left clamping plate 18 is attached to the upper end face of the bottom of the second boom section 29; the right clamping plate 19 is fixedly connected to the right fixing block 21 with bolts, so that the vertical side flange of the right clamping plate 19 is attached to the right end face of the bottom of the second boom section 29, and the horizontal side flange of the right clamping plate 19 is attached to the upper end face of the bottom of the second boom section 29; thus, the bottom of the second boom section 29 is positioned in the width direction and in the height direction (i.e., the vertical direction).

[0053] Similarly, the second limiting device 17b, the third limiting device 17c, and the fourth limiting device 17d are operated to position the corresponding positions at the bottom of the second arm section 29.

[0054] Fifth step, the second arm section 29 is provided with an upper chord 29-1, and the upper chord positioning ear plate 3 is fixedly connected to the front end of the upper chord 29-1 with bolts.

[0055] Step 6: Place the first arm section 28 on platform 23-1 of the left connecting block 23 and platform 25 of the first width-direction limiting mechanism 22a (the two platforms support the front of the first arm section 28). Then place the first arm section 28 on platforms of the left and right connecting blocks of the second width-direction limiting mechanism 22b, the third width-direction limiting mechanism 22c, the fourth width-direction limiting mechanism 22d, and the fifth width-direction limiting mechanism 22e. The five sets of width-direction limiting mechanisms support the first arm section 28. Bolts are used to fix the left straight clamping plate 24 of the first width direction limiting mechanism 22a to the left connecting block 23, and bolts are used to fix the right straight clamping plate 26 to the right connecting block 25. In this way, the inner side of the left straight clamping plate 24 abuts against the left end face of the bottom of the first arm section 28, and the inner side of the right straight clamping plate 26 abuts against the right end face of the bottom of the first arm section 28, thereby achieving positioning of the first arm section 28 along the width direction. Similarly, the left and right straight clamping plates of the second width direction limiting mechanism 22b, the third width direction limiting mechanism 22c, the fourth width direction limiting mechanism 22d, and the fifth width direction limiting mechanism 22e are used to position the first arm section 28. Bring the front end face of the bottom of the first arm segment 28 to abut the rear end face of the bottom of the second arm segment 29.

[0056] Step 7: Operate the third lifting device 27c to raise its crossbar, lifting the first boom section 28; operate the first lifting device 27a to raise its crossbar 27, lifting the first boom section 28, thereby causing the bottom of the first boom section 28 to no longer be horizontal, but tilted upwards at a certain angle, as... Figure 14 and 16 As shown, the rear end of the bottom of the first arm segment 28 is higher than the front end of the bottom, that is, the first arm segment 28 is tilted upwards, and the plane where the bottom of the first arm segment 28 is located has a certain angle (e.g., 5° to 10°) with the plane where the bottom of the second arm segment 29 is located.

[0057] Step 8, refer to Figure 16Welding is performed at the gap between the front end face of the bottom of the first arm section 28 and the rear end face of the bottom of the second arm section 29 to achieve a fixed connection between the bottoms of the first arm section 28 and the second arm section 29. A thin iron plate can be inserted into the gap between the front end face of the bottom of the first arm section 28 and the rear end face of the bottom of the second arm section 29, and then welded. Then, the front end of the upper chord 28-1 of the first arm section 28 and the rear end of the upper chord 29-1 are fixedly connected with bolts or pins. This completes the welding assembly of the first arm section 28 and the second arm section 29.

[0058] Step 9: Remove the bolts connecting the upper chord positioning ear plate 3 and the front end of the upper chord 29-1, then disassemble the various width-direction limiting mechanisms and limiting devices, and finally remove the assembly formed by the first arm section 28 and the second arm section 29.

[0059] Step 10: If welding and assembling the third arm section is required, move the first arm section 28 and the second arm section 29 assembly backward, leaving a gap between the second arm section 29 and the vertical support 2. There are two scenarios: ① Repeat the above steps to weld and assemble the third arm section and the second arm section 29. Generally, the length of the third arm section is approximately equal to the length of the second arm section 29. During operation, the second arm section 29 is tilted upward, and there is a certain angle (e.g., 5°–10°) between the bottom of the second arm section 29 and the bottom of the third arm section. Continue in this manner to weld and assemble the fourth arm section.

[0060] The second scenario involves not using a lifting device to raise the second boom section 29 upwards at a certain angle. Instead, the second boom section 29 is pressed against the platforms of the left and right connecting blocks in the width-direction limiting mechanisms, ensuring that the third boom section and the second boom section 29 are on the same horizontal plane. This process is repeated for the welding and assembly of the fourth boom section. The final crane boom assembly only has the very end boom section, the first boom section 28, tilted upwards at a certain angle.

[0061] As can be seen, this fixture can tilt the end section of the crane boom upwards, thereby increasing strength and stress during operation, and improving operational safety. The same effect can be achieved by tilting other boom sections upwards as well. Therefore, the welding and assembly process is highly efficient and easy to operate.

[0062] The positions of the first positioning plate 10 and the second positioning plate 16 are adjusted by the first axial positioning mechanism and the second axial positioning mechanism to adapt to boom sections of different lengths.

[0063] To accommodate boom sections of different specifications, pads are placed in the pad placement slots of the limiting device and the pad placement slots of the width limiting mechanism. The bottom of the boom section is pressed on the pads, that is, the boom section is supported by the pads.

[0064] It should be noted that other fixing mechanisms can be used to replace the upper chord positioning ear plate 3.

Claims

1. A welding fixture for adjustable angle of tower crane boom, characterized in that, The system includes a horizontal base, a vertical support, a fixing mechanism, a first axial positioning mechanism, a second axial positioning mechanism, a first lifting device, a third lifting device, multiple limiting devices, and multiple width-direction limiting mechanisms. The vertical support is fixedly connected to the front end of the horizontal base, and the fixing mechanism is fixedly connected to the top of the vertical support. The first axial positioning mechanism includes a first handwheel, a first lead screw, a first telescopic plate, a first nut, a first telescopic shaft, a second telescopic shaft, and a first positioning plate. The first lead screw is rotatably connected to the bottom of the vertical support, the first handwheel is connected to the end of the first lead screw, the first nut is connected to the first lead screw, and the first telescopic plate is fixedly connected to the first nut. The first and second telescopic shafts pass through the bottom of the vertical support and are slidable. The first positioning plate is fixedly connected to the ends of the first and second telescopic shafts. The second axial positioning mechanism includes a second handwheel, a second lead screw, a second telescopic plate, a second nut, a third telescopic shaft, a fourth telescopic shaft, and a second positioning plate. The second lead screw is rotatably connected to the bottom of the vertical support. The second handwheel is fixedly connected to the end of the second lead screw. The second nut is connected to the second lead screw. The second telescopic plate is fixedly connected to the second nut. The third and fourth telescopic shafts pass through the bottom of the vertical support and are slidable. The second positioning plate is fixedly connected to the ends of the third and fourth telescopic shafts.

2. The adjustable angle welding fixture for tower crane boom according to claim 1, characterized in that, The limiting device includes a clamping plate connecting beam, a left clamping plate, a right clamping plate, a left fixing block, and a right fixing block. The left fixing block is fixedly connected to the left end of the clamping plate connecting beam, and the right fixing block is fixedly connected to the right end of the clamping plate connecting beam. The left clamping plate is detachably connected to the left fixing block, and the right clamping plate is detachably connected to the right fixing block. The left clamping plate has a vertical side guard and a horizontal side guard, and the right clamping plate has a vertical side guard and a horizontal side guard. The left fixing block has a platform, and the right fixing block has a platform. The clamping plate connecting beam is fixedly connected to a horizontal base. The multiple limiting devices are arranged side by side along the width direction of the horizontal base, and the first limiting device among the multiple limiting devices is close to the second axial positioning mechanism and the first axial positioning mechanism. The width-direction limiting mechanism includes a straight plate mounting beam, a left connecting block, a left straight plate, a right connecting block, and a right straight plate. The left connecting block is fixedly connected to the left end of the straight plate mounting beam, and the right connecting block is fixedly connected to the right end of the straight plate mounting beam. The left straight plate is detachably connected to the left connecting block, and the right straight plate is detachably connected to the right connecting block. The left connecting block has a platform, and the right connecting block has a platform. The straight plate mounting beam is fixedly connected to a horizontal base. Multiple width-direction limiting mechanisms are arranged side by side along the width direction of the horizontal base. The plurality of width-direction limiting mechanisms are located at the rear part of the horizontal base, the plurality of limiting devices are located at the front part of the horizontal base, and the first width-direction limiting mechanism among the plurality of width-direction limiting mechanisms is located behind the last limiting device among the plurality of limiting devices. The first lifting device includes a crossbar, a left manual screw jack, and a right manual screw jack. The left end of the crossbar is connected to the output end of the left manual screw jack, and the right end of the crossbar is connected to the output end of the right manual screw jack. The crossbar is located above the horizontal base, and the left and right manual screw jacks are located on opposite sides of the horizontal base. The first lifting device is located between the last limiting device among multiple limiting devices and the first width-direction limiting mechanism among multiple width-direction limiting mechanisms. The third lifting device includes a crossbar, a left-side manual screw jack, and a right-side manual screw jack; The third lifting device is located between the last two of the multiple width-direction limiting mechanisms.

3. The adjustable angle welding fixture for tower crane boom according to claim 2, characterized in that, The plurality of limiting devices are a first limiting device, a second limiting device, a third limiting device, and a fourth limiting device, and the plurality of width-direction limiting mechanisms are a first width-direction limiting mechanism, a second width-direction limiting mechanism, a third width-direction limiting mechanism, a fourth width-direction limiting mechanism, and a fifth width-direction limiting mechanism.

4. The adjustable angle welding fixture for tower crane boom according to claim 2 or 3, characterized in that, The left fixing block is provided with a pad placement groove, and the right fixing block is provided with a pad placement groove; the left connecting block is provided with a pad groove, and the right connecting block is provided with a pad groove.

5. The adjustable angle welding fixture for tower crane boom according to claim 2 or 3, characterized in that, The fixing mechanism is the upper chord positioning lug.

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