A positioning and clamping fixture for welding automobile frames

Abstract

This invention discloses a positioning and clamping fixture for automotive frame welding, relating to the field of automotive manufacturing equipment technology. It includes a worktable, with a welding angle adjustment mechanism on the top of the worktable, and a dynamic compensation positioning and clamping mechanism for thermal deformation on top of the welding angle adjustment mechanism. A PLC controller is mounted on the top of the worktable. This positioning and clamping fixture for automotive frame welding, through the dynamic compensation positioning and clamping mechanism for thermal deformation, corrects positional deviations caused by thermal deformation in real time, preventing dimensional inaccuracies in the welded parts of the frame from exceeding tolerances, reducing subsequent straightening processing steps, and lowering production costs. It solves the problem that existing fixtures using fixed rigid clamping and positioning structures cannot correct positional deviations caused by thermal deformation in real time, resulting in dimensional inaccuracies in the welded parts of the frame exceeding tolerances and requiring additional straightening processing during subsequent assembly, thus increasing production costs.

Description

Technical Field

[0001] This invention relates to the field of automobile manufacturing equipment technology, specifically to a positioning and clamping fixture for welding automobile frames. Background Technology

[0002] In the automobile manufacturing process, the welding quality of the car frame directly affects the overall performance and safety of the vehicle, and positioning and clamping fixtures are key equipment to ensure the welding quality of the car frame. With the rapid development of the automotive industry, the production of car frames is gradually shifting towards mass production, which places higher demands on the efficiency and automation of fixtures.

[0003] For example, the subframe welding fixture with Chinese announcement number CN203292742U states in its specification that "This utility model discloses a new type of subframe welding fixture, applicable to the field of automotive parts process equipment. It includes a fixture base, a clamping mechanism, and a positioning mechanism. The fixture base is provided with a clamping mechanism and a positioning mechanism. The clamping mechanism includes a pneumatic cylinder and a clamping block. The clamping block is connected to the piston rod of the pneumatic cylinder. The entire fixture is set on a movable support platform."

[0004] However, the existing devices have the following shortcomings during use:

[0005] In existing fixtures, the car subframe is placed in the corresponding position on the positioning mechanism, and the pneumatic cylinder is activated to push the clamping block to press the subframe, allowing welding to proceed. The workpiece positioning is quick and accurate, clamping is convenient and labor-saving, and the complexity of welding assembly positioning and clamping processes is reduced. At the same time, it transforms welds in spatially poor welding conditions into flat welds in more favorable welding conditions, maximizing welding quality. However, during the welding process of the car frame, the metal components of the car frame are prone to thermal deformation due to the high welding temperature, causing the positioning reference of the fixture to shift. The existing fixtures use a fixed rigid clamping and positioning structure, which cannot correct the positional deviation caused by thermal deformation in real time, resulting in dimensional inaccuracies of the welded parts of the car frame exceeding tolerances. Additional correction processing is required during subsequent assembly, increasing production costs.

[0006] Therefore, we propose a positioning and clamping fixture for automotive frame welding to solve the problems mentioned above. Summary of the Invention

[0007] The purpose of this invention is to provide a positioning and clamping fixture for welding automotive frames. The fixture involves horizontally mounting the frame to be welded on positioning pins, then driving a cylinder to clamp the frame with two clamping blocks. During welding, multiple temperature sensors embedded in the top of the fixing box can detect temperature changes in different welding areas in real time, while positioning sensors simultaneously capture the frame's position information. Both transmit the data to a PLC controller in real time. The PLC controller has a built-in thermal deformation compensation algorithm. Based on the position deviation data collected by the positioning sensors and the temperature data collected by the temperature detection module, it calculates the required compensation amount. When the PLC controller analyzes that the frame has undergone thermal deformation due to high temperature, it drives the threaded rod to rotate via a drive mechanism, causing the movable seat sleeved on the threaded rod to move smoothly along the guide rod. Simultaneously, the cylinder can adjust its output force based on the pressure data fed back by the pressure sensor, driving the clamping blocks to fine-tune the clamping position, thereby correcting the position deviation caused by thermal deformation in real time and solving the problems mentioned in the background art.

[0008] To achieve the above objectives, the present invention provides the following technical solution: a positioning and clamping fixture for welding automobile frames, comprising a worktable, a welding angle adjustment mechanism being provided on the top of the worktable, a heat deformation dynamic compensation positioning and clamping mechanism being provided on the top of the welding angle adjustment mechanism, and a PLC controller being installed on the top of the worktable;

[0009] The dynamic compensation positioning and clamping mechanism for thermal deformation includes two fixed plates, a guide rod fixedly connected between the two fixed plates, and a threaded rod rotatably connected between the two fixed plates. A movable seat is threaded onto the outer surface of the guide rod and the threaded rod. A fixed box is mounted on the top of the movable seat. Four positioning pins are provided inside the fixed box, with the top ends of the four positioning pins movably penetrating through the fixed box. The four positioning pins are arranged according to four suspension points on the vehicle frame. Multiple temperature sensors for real-time detection of temperature changes in different welding areas are embedded in the top of the fixed box. Two positioning sensors for real-time detection of vehicle frame position information are also embedded in the top of the fixed box. Two cylinders are mounted on one side of the two fixed plates, with the output ends of the two cylinders movably penetrating through the two fixed plates and fixedly connected to two pressure sensors. Two clamping blocks are fixedly connected to one side of the two pressure sensors. A drive mechanism for driving the threaded rod to rotate is provided on one side of one of the fixed plates.

[0010] Preferably, the welding angle adjustment mechanism includes a first servo motor fixedly installed at the bottom of the workbench, the output end of the first servo motor movably passing through the workbench and fixedly connected to a rotary disk.

[0011] Preferably, the top of the workbench is provided with an annular groove, and the bottom of the rotary disk is equipped with multiple supporting casters.

[0012] Preferably, the driving mechanism includes two support plates fixedly connected to one side of one of the fixed plates, and a worm gear is rotatably connected between the two support plates.

[0013] Preferably, the smooth end of the threaded rod movably passes through one of the fixed plates, and a worm gear is fixedly sleeved on the outer surface of the threaded rod, with the worm meshing with the worm gear.

[0014] Preferably, a second servo motor is fixedly installed on one side of one of the support plates, and the output end of the second servo motor movably passes through one of the support plates and is fixedly connected to the worm gear.

[0015] Preferably, the fixed box is provided with a positioning telescopic withdrawal mechanism, which includes an electric push rod fixedly installed inside the fixed box, a lifting plate fixedly connected to the telescopic end of the electric push rod, and four positioning pins installed on the top of the lifting plate.

[0016] Preferably, the inner side of the fixed box has two sliding grooves, and two sliding plates are slidably connected in the two sliding grooves, and the lifting plate is fixedly connected between the two sliding plates.

[0017] Preferably, two guide rails are mounted on the top of the rotating disk, and two guide blocks are slidably connected on the two guide rails, with the tops of the two guide blocks fixedly connected to the movable seat.

[0018] Preferably, four movable rods are fixedly connected to one side of the two clamping blocks, and the four movable rods move through the two fixed plates.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] 1. This invention utilizes a dynamic thermal deformation compensation positioning and clamping mechanism to horizontally mount the frame to be welded onto positioning pins. A drive cylinder then clamps the frame with two clamping blocks. During welding, multiple temperature sensors embedded in the top of the fixing box detect real-time temperature changes in different welding areas, while positioning sensors simultaneously capture the frame's position information. Both transmit the data to a PLC controller in real-time. The PLC controller has a built-in thermal deformation compensation algorithm that calculates the required compensation amount based on the position deviation data collected by the positioning sensors and the temperature data collected by the temperature detection module. When the PLC controller analyzes that the frame is experiencing thermal deformation due to high temperature... During thermal deformation, the drive mechanism rotates the threaded rod, causing the movable seat sleeved on the threaded rod to move smoothly along the guide rod. At the same time, the cylinder can adjust the output force according to the pressure data fed back by the pressure sensor, driving the clamping block to fine-tune the clamping position, thereby correcting the positional deviation caused by thermal deformation in real time. This avoids dimensional inaccuracies in the welded parts of the frame, reduces subsequent straightening processing, lowers production costs, and solves the problem that existing fixtures use a fixed rigid clamping and positioning structure, which cannot correct the positional deviation caused by thermal deformation in real time, resulting in dimensional inaccuracies in the welded parts of the frame, requiring additional straightening processing during subsequent assembly, and increasing production costs.

[0021] 2. This invention, by setting up a welding angle adjustment mechanism, when the welding angle needs to be adjusted, the PLC controller controls the first servo motor to start, and the output end of the first servo motor drives the rotating disk to rotate. The heat deformation dynamic compensation positioning clamping mechanism on the top of the rotating disk rotates together, thereby adjusting the welding angle of the frame to meet the welding requirements of welds in different positions. It is convenient to convert welds in complex spatial positions into welds in flat positions with better welding conditions, further ensuring welding quality and improving the flexibility and convenience of frame welding. At the same time, multiple support casters at the bottom of the rotating disk roll in the annular groove on the top of the worktable, which not only provides stable support for the rotating disk, but also reduces frictional resistance during rotation, making the angle adjustment more stable and precise, and improving the efficiency of the overall welding operation.

[0022] 3. This invention incorporates a positioning telescopic withdrawal mechanism. During frame clamping, the PLC controller activates an electric push rod, whose telescopic end pushes the lifting plate upwards. The lifting plate then causes the four positioning pins at the top to rise synchronously, with the tops of the positioning pins extending out of the fixing box. This facilitates the installation of the corresponding four suspension points on the frame onto the positioning pins, completing the initial positioning of the frame. After welding is completed, the electric push rod lowers the lifting plate, and the positioning pins retract into the fixing box. At this point, the frame can be easily removed from the fixture without the need for manual disassembly of the positioning structure, simplifying the operation process and improving workpiece loading and unloading efficiency. Furthermore, the sliding plates on both sides of the lifting plate slide within the grooves inside the fixing box, effectively limiting the movement trajectory of the lifting plate and ensuring the stability and accuracy of the positioning pins during telescopic movement. Attached Figure Description

[0023] Figure 1 This is a perspective view of the main structure of a positioning and clamping fixture for welding an automobile frame according to the present invention;

[0024] Figure 2 This is a perspective view of the right side structure of a positioning and clamping fixture for welding an automobile frame according to the present invention;

[0025] Figure 3 This is a perspective view of the bottom structure of a positioning and clamping fixture for welding an automobile frame according to the present invention;

[0026] Figure 4 This is a perspective view of the rear structure of a positioning and clamping fixture for welding an automobile frame according to the present invention;

[0027] Figure 5 This is a perspective view of a portion of the worktable structure in a positioning and clamping fixture for welding automobile frames according to the present invention;

[0028] Figure 6 This is a perspective view of the unfolded structure of the movable seat and threaded rod in a positioning and clamping fixture for welding automobile frames according to the present invention.

[0029] Figure 7 This is a perspective view of a portion of the structure of the fixing plate in a positioning and clamping fixture for welding automobile frames according to the present invention;

[0030] Figure 8 This is a partial sectional perspective view of the fixing box in a positioning and clamping fixture for welding automobile frames according to the present invention.

[0031] In the diagram: 1. Workbench; 2. Welding angle adjustment mechanism; 201. First servo motor; 202. Rotary disk; 203. Annular groove; 204. Support caster wheel; 3. Dynamic compensation positioning and clamping mechanism for thermal deformation; 301. Fixed plate; 302. Guide rod; 303. Threaded rod; 304. Moving seat; 305. Fixed box; 306. Positioning pin; 307. Temperature sensor; 308. Positioning sensor; 309. Cylinder; 310. Pressure sensor; 311. Clamping block; 312. Guide rail; 313. Guide block; 314. Movable rod; 4. Drive mechanism; 401. Support plate; 402. Worm gear; 403. Worm wheel; 404. Second servo motor; 5. Positioning telescopic withdrawal mechanism; 501. Electric push rod; 502. Lifting plate; 503. Slide groove; 504. Slide plate; 6. PLC controller. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. 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.

[0033] like Figure 1 - Figure 8 As shown, the present invention provides a technical solution: a positioning and clamping fixture for welding automobile frames, including a worktable 1, a welding angle adjustment mechanism 2 is provided on the top of the worktable 1, a heat deformation dynamic compensation positioning and clamping mechanism 3 is provided on the top of the welding angle adjustment mechanism 2, and a PLC controller 6 is installed on the top of the worktable 1.

[0034] The dynamic compensation positioning and clamping mechanism 3 for thermal deformation includes two fixed plates 301. A guide rod 302 is fixedly connected between the two fixed plates 301, and a threaded rod 303 is rotatably connected between the two fixed plates 301. A movable seat 304 is threaded onto the outer surfaces of the guide rod 302 and the threaded rod 303. A fixed box 305 is mounted on the top of the movable seat 304. Four positioning pins 306 are provided inside the fixed box 305. The top ends of the four positioning pins 306 move through the fixed box 305, and the four positioning pins 306 are set according to the four suspension points on the frame. The part is embedded with multiple temperature sensors 307 for real-time detection of temperature changes in different welding areas. The top of the fixed box 305 is embedded with two positioning sensors 308 for real-time detection of frame position information. Two cylinders 309 are installed on one side of the two fixed plates 301. The output ends of the two cylinders 309 move through the two fixed plates 301 and are fixedly connected to two pressure sensors 310. Two clamping blocks 311 are fixedly connected to one side of the two pressure sensors 310. One side of one of the fixed plates 301 is provided with a drive mechanism 4 for driving the threaded rod 303 to rotate.

[0035] like Figure 1 and Figure 3 As shown, the welding angle adjustment mechanism 2 includes a first servo motor 201 fixedly installed at the bottom of the workbench 1. The output end of the first servo motor 201 extends through the workbench 1 and is fixedly connected to a rotating disk 202. The first servo motor 201 has high-precision pulse control characteristics and can accurately adjust the rotation angle according to the instructions issued by the PLC controller 6. This ensures that when the rotating disk 202 drives the frame on it to adjust the welding angle, the angle deviation is controlled within a very small range, perfectly meeting the precise requirements of welding angle for welds at different positions, improving the weld formation quality and the convenience of welding operations.

[0036] like Figure 1 , Figure 3 and Figure 5 As shown, the top of the workbench 1 has an annular groove 203, and the bottom of the rotary disk 202 is equipped with multiple supporting casters 204. The annular groove 203 on the top of the workbench 1 provides a movement trajectory for the supporting casters 204 at the bottom of the rotary disk 202, effectively preventing the supporting casters 204 from shifting laterally during rotation, ensuring that the rotary disk 202 always rotates smoothly around a fixed axis, and improving the stability of angle adjustment. The multiple supporting casters 204 are evenly distributed in a circular array at the bottom of the rotary disk 202, which can evenly distribute the weight of the frame and the thermal deformation dynamic compensation positioning clamping mechanism 3, etc., reduce the load pressure on the first servo motor 201, and extend the service life of the first servo motor 201. At the same time, the rolling friction resistance of the supporting casters 204 is much smaller than that of sliding friction, making the rotary disk 202 rotate more smoothly under the drive of the first servo motor 201, reducing energy consumption during angle adjustment, and avoiding direct contact and friction between the bottom of the rotary disk 202 and the top of the workbench 1, reducing wear on both and improving the overall service life of the fixture.

[0037] like Figure 1 and Figure 6 As shown, the drive mechanism 4 includes two support plates 401 fixedly connected to one side of one of the fixed plates 301. A worm gear 402 is rotatably connected between the two support plates 401. The two support plates 401 are vertically fixed to one side of one of the fixed plates 301, providing symmetrical and stable installation support for the worm gear 402. This ensures that the worm gear 402 keeps its axis fixed during rotation, avoiding problems such as uneven meshing clearance with the worm wheel 403 and transmission jamming caused by axial or radial offset of the worm gear 402. At the same time, it facilitates subsequent maintenance personnel to lubricate, clean, or troubleshoot the worm gear 402, reducing the difficulty and cost of equipment maintenance.

[0038] like Figure 4 and Figure 6 As shown, the smooth end of the threaded rod 303 moves through one of the fixed plates 301. A worm gear 403 is fixedly sleeved on the outer surface of the threaded rod 303. The worm 402 meshes with the worm gear 403. Through the meshing connection between the worm 402 and the worm gear 403 fixedly sleeved on the outer surface of the threaded rod 303, this transmission combination has the characteristics of speed reduction and torque increase. It can convert the high speed output by the second servo motor 404 into the low speed and high torque of the threaded rod 303, ensuring that the moving seat 304 has more power when driving the fixed box 305 and the frame to finely adjust the position. Even if the frame is thermally deformed due to the high temperature of welding, resulting in increased local resistance, it can still move smoothly. At the same time, the self-locking property of the meshing transmission between the worm 402 and the worm gear 403 can prevent the threaded rod 303 from rotating on its own in the non-drive state, ensuring the stability of the moving seat 304, avoiding accidental displacement of the frame during the welding process, and ensuring welding accuracy.

[0039] like Figure 1 , Figure 4 and Figure 6 As shown, a second servo motor 404 is fixedly installed on one side of one of the support plates 401. The output end of the second servo motor 404 movably passes through one of the support plates 401 and is fixedly connected to the worm gear 402. The second servo motor 404 is fixed to the outside of one of the support plates 401 by bolts. Its output end passes through the support plate 401 and is fixed to one end of the worm gear 402 by a coupling or key connection, so that the second servo motor 404 and the worm gear 402 can directly drive each other, reducing intermediate transmission components such as gears and belts, reducing transmission errors and component failure risks. The second servo motor 404 can achieve precise speed and steering control through the pulse signal output by the PLC controller 6. It can accurately adjust the rotation angle of the worm gear 402 according to the frame position deviation data fed back by the positioning sensor 308, thereby controlling the number of rotations of the threaded rod 303, so that the displacement of the moving seat 304 accurately matches the thermal deformation compensation requirements, avoiding positioning deviations caused by over-adjustment or under-adjustment, ensuring the compensation accuracy of the thermal deformation dynamic compensation positioning clamping mechanism 3, and ensuring the dimensional accuracy of the frame welding parts.

[0040] like Figure 1 and Figure 8 As shown, a positioning telescopic withdrawal mechanism 5 is provided inside the fixed box 305. The positioning telescopic withdrawal mechanism 5 includes an electric push rod 501 fixedly installed inside the fixed box 305. The telescopic end of the electric push rod 501 is fixedly connected to a lifting plate 502. Four positioning pins 306 are installed on the top of the lifting plate 502. The electric push rod 501 can provide a stable linear driving force to the lifting plate 502, driving the lifting plate 502 to rise and fall smoothly in the vertical direction. This enables the four positioning pins 306 installed on the top of the lifting plate 502 to extend and retract synchronously, avoiding asynchronous extension and retraction speeds or strokes of individual positioning pins 306 that could cause damage to the frame. To address issues such as clamp tilting and inaccurate positioning, four positioning pins 306 are fixed to the top of the lifting plate 502 according to the spacing of the frame suspension points. This ensures that the four positioning pins 306 maintain a fixed relative position and are precisely aligned with the four suspension points at the bottom of the frame, improving the initial positioning accuracy of the frame. At the same time, the extension and retraction stroke of the electric push rod 501 can be preset or adjusted in real time by the PLC controller 6. This allows for flexible adjustment of the length of the positioning pins 306 extending from the top of the fixed box 305 according to the height requirements of the suspension points of different vehicle models. This improves the adaptability of the thermal deformation dynamic compensation positioning clamping mechanism 3 to different vehicle models and enhances the versatility of the clamp.

[0041] like Figure 1 and Figure 8As shown, the inner side of the fixed box 305 has two sliding grooves 503, and two sliding plates 504 are slidably connected in the two sliding grooves 503. The lifting plate 502 is fixedly connected between the two sliding plates 504. The two sliding grooves 503 symmetrically opened on the inner side of the fixed box 305 form a sliding fit structure with the sliding plates 504 fixed on both sides of the lifting plate 502, which restricts the movement direction of the lifting plate 502 and ensures that the lifting plate 502 can only be raised and lowered smoothly in the vertical direction, avoiding tilting, deviation or jamming during the lifting process. This ensures that the four positioning pins 306 always remain in a vertical state when they extend and retract, preventing jamming, wear or positioning deviation when the positioning pins 306 are engaged with the frame suspension points.

[0042] like Figure 1 , Figure 4 and Figure 6 As shown, two guide rails 312 are mounted on the top of the rotary disk 202. Two guide blocks 313 are slidably connected to the two guide rails 312, and the tops of the two guide blocks 313 are fixedly connected to the movable seat 304. The two guide rails 312, which are parallel to each other on the top of the rotary disk 202, provide a precise linear motion trajectory for the sliding guide blocks 313, ensuring that the movable seat 304 moves linearly along the direction of the guide rails 312 under the drive of the threaded rod 303, avoiding lateral deviation. This ensures the relative position stability of components such as the positioning pin 306, temperature sensor 307, and positioning sensor 308 on the top fixed box 305 of the movable seat 304 with the frame, improving the accuracy of the thermal deformation dynamic compensation positioning clamping mechanism 3. At the same time, the cooperation between the guide rails 312 and the guide blocks 313 can disperse the radial pressure of the movable seat 304 on the threaded rod 303, reducing the risk of bending deformation of the threaded rod 303 due to uneven force.

[0043] like Figure 1 , Figure 4 , Figure 5 , Figure 6 , Figure 7 and Figure 8As shown, four movable rods 314 are fixedly connected to one side of the two clamping blocks 311, and the four movable rods 314 movably pass through the two fixed plates 301. The movable rods 314 provide stable guiding support for the clamping blocks 311, ensuring that the clamping blocks 311 move linearly along the axis of the movable rods 314 under the drive of the cylinder 309. This prevents the clamping blocks 311 from tilting or deflecting, ensuring that the clamping force of the clamping blocks 311 on the frame is evenly applied to both sides of the frame, preventing local deformation or positioning displacement of the frame due to uneven clamping force. Simultaneously, the length of the movable rods 314 passing through the fixed plates 301 limits the maximum range of movement of the clamping blocks 311, preventing the cylinder 309 from over-exerting its position. The extension and retraction cause the clamping block 311 to collide with the fixed box 305 or other components, improving the operational safety of the dynamic compensation positioning clamping mechanism 3 for thermal deformation. Furthermore, the pressure sensor 310 between the clamping block 311 and the output end of the cylinder 309 can provide real-time feedback on the clamping force data. Combined with the guiding effect of the movable rod 314, the clamping force can be precisely controlled, further ensuring clamping accuracy and frame safety. Moreover, the first servo motor 201, temperature sensor 307, positioning sensor 308, cylinder 309, pressure sensor 310, second servo motor 404, and electric push rod 501 are all electrically connected to the PLC controller 6, realizing centralized intelligent control of the core components of the fixture.

[0044] The usage method and working principle of this device: During the device initialization stage, the device power is turned on and the PLC controller 6 is started. The PLC controller 6 initializes and resets the first servo motor 201, the second servo motor 404, the cylinder 309, the electric push rod 501 and other components to ensure that the rotating disk 202 is at the initial angle, the moving seat 304 is in the middle position of the guide rail 312, the clamping block 311 is in the open state, and the positioning pin 306 is retracted into the fixed box 305.

[0045] During the positioning extension stage, the PLC controller 6 sends a command to control the electric push rod 501 in the positioning telescopic withdrawal mechanism 5 to extend. The electric push rod 501 pushes the lifting plate 502 to move upward along the slide groove 503 inside the fixed box 305, which drives the four positioning pins 306 on the top of the lifting plate 502 to extend synchronously from the top of the fixed box 305 until the extension length of the positioning pins 306 is adapted to the height of the suspension point of the frame to be welded.

[0046] During the frame positioning and clamping stage, the frame to be welded is horizontally mounted on the positioning pin 306. The two cylinders 309 in the thermal deformation dynamic compensation positioning and clamping mechanism 3 are extended by the PLC controller 6. The cylinders 309 push the pressure sensor 310 and the clamping block 311 to move towards the frame. At the same time, the movable rod 314 slides synchronously along the fixed plate 301 with the clamping block 311 to provide guidance until the clamping block 311 is in contact with both sides of the frame. The pressure sensor 310 transmits the clamping force data to the PLC controller 6 in real time. When the clamping force reaches the preset value, the PLC controller 6 controls the cylinders 309 to stop extending, thus completing the frame clamping.

[0047] During the welding angle adjustment stage, the position of the weld to be welded is used to determine whether the welding angle needs to be adjusted. If adjustment is required, the target angle parameter is input through the PLC controller 6. The PLC controller 6 sends a command to the first servo motor 201 in the welding angle adjustment mechanism 2. The first servo motor 201 drives the rotating disk 202 to rotate. The support casters 204 at the bottom of the rotating disk 202 roll along the annular groove 203 at the top of the worktable 1. At the same time, the thermal deformation dynamic compensation positioning clamping mechanism 3 and the frame at the top of the rotating disk 202 rotate synchronously with the rotating disk 202 until the rotating disk 202 rotates to the target angle. The PLC controller 6 then controls the first servo motor 201 to stop, completing the welding angle adjustment.

[0048] During the welding and real-time monitoring phase, after the angle adjustment is completed, the welding equipment is started to weld the target weld seam of the frame. During the welding process, multiple temperature sensors 307 on the top of the fixed box 305 collect temperature data of different welding areas in real time, and the positioning sensor 308 captures the position offset information of the frame in real time. Both transmit the data synchronously to the PLC controller 6. The PLC controller 6 calculates the amount of compensation displacement to be adjusted by combining the temperature data of the temperature sensors 307 and the position deviation data of the positioning sensor 308 through the built-in thermal deformation compensation algorithm. Then, the PLC controller 6 controls the second servo motor 404 in the drive mechanism 4 to start. The second servo motor 404 drives the worm gear 402 to rotate. The worm gear 402 meshes with the worm wheel 403 on the outer surface of the threaded rod 303 to drive the threaded rod 302. 3. Rotation: The threaded rod 303 drives the movable seat 304 to move smoothly along the guide rod 302. During this process, in order to avoid positional displacement or surface damage to the frame due to changes in clamping force during movement, the PLC controller 6 will synchronously receive the clamping force data fed back by the pressure sensor 310 and adjust the extension and retraction of the cylinder 309 in real time, driving the clamping block 311 to make adaptive fine adjustments. If the clamping force increases due to changes in the frame position during movement, the cylinder 309 will be shortened appropriately to reduce the clamping force; if the clamping force decreases, the cylinder 309 will be extended appropriately to supplement the clamping force, always ensuring that the clamping force is stable within the preset range and the frame position is accurate, until the movable seat 304 drives the frame to complete displacement compensation and position deviation correction. Then, the PLC controller 6 controls the second servo motor 404 to stop, and the cylinder 309 also returns to the stable clamping state.

[0049] During the welding completion and removal stage, after all welds are completed, the welding equipment is turned off. The cylinder 309 is shortened by the PLC controller 6, which moves the clamping block 311 away from the frame until the clamping block 311 is completely detached from the frame and the clamping state is released. The PLC controller 6 then controls the electric push rod 501 to shorten, which causes the lifting plate 502 and the positioning pin 306 to retract into the fixed box 305 simultaneously, so as to prevent the positioning pin 306 from obstructing the removal of the frame.

[0050] The wiring diagrams for the first servo motor 201, temperature sensor 307, positioning sensor 308, cylinder 309, pressure sensor 310, second servo motor 404, electric actuator 501, and PLC controller 6 in this invention are common knowledge in the field, and their working principles are known technologies. The appropriate model is selected according to actual use. Therefore, the control methods and wiring layouts for the first servo motor 201, temperature sensor 307, positioning sensor 308, cylinder 309, pressure sensor 310, second servo motor 404, electric actuator 501, and PLC controller 6 will not be explained in detail.

[0051] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A positioning and clamping fixture for welding automobile frames, characterized in that, The workbench (1) is provided with a welding angle adjustment mechanism (2) on the top of the workbench (1), a heat deformation dynamic compensation positioning clamping mechanism (3) is provided on the top of the welding angle adjustment mechanism (2), and a PLC controller (6) is installed on the top of the workbench (1). The thermal deformation dynamic compensation positioning clamping mechanism (3) includes two fixed plates (301), a guide rod (302) is fixedly connected between the two fixed plates (301), and a threaded rod (303) is rotatably connected between the two fixed plates (301). A movable seat (304) is threaded onto the outer surface of the guide rod (302) and the threaded rod (303). A fixed box (305) is installed on the top of the movable seat (304). Four positioning pins (306) are provided inside the fixed box (305). The top ends of the four positioning pins (306) move through the fixed box (305), and the four positioning pins (306) are set according to the four suspension points on the frame. Multiple temperature sensors (307) for real-time detection of temperature changes in different welding areas are embedded in the top of the fixed box (305). Two positioning sensors (308) for real-time detection of frame position information are embedded in the top of the fixed box (305). Two cylinders (309) are installed on one side of the two fixed plates (301). The output ends of the two cylinders (309) pass through the two fixed plates (301) and are fixedly connected to two pressure sensors (310). Two clamping blocks (311) are fixedly connected to one side of the two pressure sensors (310). A drive mechanism (4) for driving the threaded rod (303) to rotate is provided on one side of one of the fixed plates (301). The welding angle adjustment mechanism (2) includes a first servo motor (201) fixedly installed at the bottom of the workbench (1). The output end of the first servo motor (201) movably passes through the workbench (1) and is fixedly connected to a rotating disk (202). The drive mechanism (4) includes two support plates (401) fixedly connected to one side of one of the fixed plates (301), and a worm gear (402) is rotatably connected between the two support plates (401). The smooth end of the threaded rod (303) is movably inserted through one of the fixed plates (301), and a worm gear (403) is fixedly sleeved on the outer surface of the threaded rod (303). The worm (402) is meshed with the worm gear (403). A second servo motor (404) is fixedly installed on one side of one of the support plates (401). The output end of the second servo motor (404) movably passes through one of the support plates (401) and is fixedly connected to the worm gear (402).

2. The positioning and clamping fixture for welding automobile frames according to claim 1, characterized in that: The top of the workbench (1) is provided with an annular groove (203), and the bottom of the rotary disk (202) is provided with multiple support casters (204).

3. The positioning and clamping fixture for welding automobile frames according to claim 1, characterized in that: The fixed box (305) is provided with a positioning telescopic exit mechanism (5). The positioning telescopic exit mechanism (5) includes an electric push rod (501) fixedly installed inside the fixed box (305). The telescopic end of the electric push rod (501) is fixedly connected to a lifting plate (502). Four positioning pins (306) are installed on the top of the lifting plate (502).

4. A positioning and clamping fixture for welding automobile frames according to claim 3, characterized in that: The inner side of the fixed box (305) has two slide grooves (503), and two slide plates (504) are slidably connected in the two slide grooves (503), and the lifting plate (502) is fixedly connected between the two slide plates (504).

5. A positioning and clamping fixture for welding automobile frames according to claim 1, characterized in that: Two guide rails (312) are mounted on the top of the rotating disk (202), and two guide blocks (313) are slidably connected on the two guide rails (312), and the tops of the two guide blocks (313) are fixedly connected to the movable seat (304).

6. The positioning and clamping fixture for welding automobile frames according to claim 1, characterized in that: Four movable rods (314) are fixedly connected to one side of the two clamping blocks (311), and the four movable rods (314) move through the two fixed plates (301).

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