A welding positioning device for assembling a storage tank and a method thereof

Abstract

The present application relates to the technical field of assembly and welding positioning of storage tank equipment, in particular to a welding positioning device for storage tank assembly and a method thereof; the device comprises a base, left / right positioning ring frames, a matching contact rod, an axial pushing rod and a seam passing inspection ruler; the device is arranged with a radial contact head having a disc spring group and a reading sleeve in the circumferential direction of the positioning ring frame, and a limited force contact chain is constructed along the radial transmission; the core is a single piece roundness discrimination and release review method, the readings are compared by the radial contact head which retreats and advances again to correct the orientation, and the real geometric deviation of the workpiece and the temporary elastic deformation induced by clamping are accurately stripped; the present application solves the problem of multi-source error coupling caused by excessive dependence on rigid locking, avoids uncontrollable rebound after the local geometric profile is forcibly corrected, and effectively improves the assembly precision of the storage tank.

Description

Technical Field

[0001] This invention relates to the field of assembly and welding positioning technology for storage tank equipment, specifically a welding positioning device and method for assembling storage tanks. Background Technology

[0002] In the assembly and welding environment of large storage tanks and pressure vessels, it is necessary to accurately align and radially round large workpieces to be spliced, such as cylinder sections or end caps, to ensure that the gap, roundness, and misalignment of the splice meet the process requirements. To achieve the above-mentioned assembly alignment, existing solutions generally use large rigid positioners or manually operated hydraulic lifting fixtures. By applying strong radial pressure and axial thrust to the pipe wall, the local geometric contour is forcibly corrected and the gap is closed. Although this solution can complete the docking task to a certain extent, it cannot separate the actual geometric deviation of the workpiece itself and the temporary elastic deformation induced by clamping due to its high dependence on rigid locking and unidirectional forced constraint, resulting in multi-source error coupling. After spot welding positioning and release of clamping force, the workpiece is prone to uncontrollable elastic rebound and stress redistribution. Moreover, the rigid structure cannot adapt to the micro-displacement caused by the thermal shrinkage of spot welding, resulting in repeated excessive misalignment and frequent local wave deformation, which cannot meet the adaptive alignment assembly requirements of the set accuracy.

[0003] Therefore, how to eliminate clamping deformation interference to achieve accurate decoupling of docking errors and improve the effectiveness of spot welding compliance adjustment has become an urgent technical problem to be solved. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention provides a welding positioning device and method for assembling storage tanks. Specifically, the technical solution of the present invention is as follows: A welding positioning device for assembling storage tanks, comprising: Base, left positioning ring frame, right positioning ring frame, aligning contact rod, axial push rod, gap inspection straightedge and control unit; The control unit is communicatively connected to the radial contact head, the axial push rod, and the gap inspection ruler; the base is a rectangular welded bed. Both the left and right positioning ring frames are vertically fixed above the base, parallel to each other and with their center lines coplanar. The left positioning ring frame is fixed to the left side of the base, while the right positioning ring frame can be adjusted and locked along the length of the base. Radial contact heads are arranged above, to the left, to the right, and below the inner circumference of the left positioning ring frame, respectively. The inner circumference of the right positioning ring frame is correspondingly arranged with radial contact heads, radial contact heads, radial contact heads, and radial contact heads; The contact rods are arranged on the right side of the left positioning ring frame, located at the top, lower left and lower right and spaced equally apart, with their front ends facing the splicing seam of the workpieces to be spliced. The axial push rod is arranged on the left side of the right positioning ring frame, corresponding to the contact rod in each direction, and contacts the end face of the workpiece to be spliced. The seam gauge is placed across both sides of the seam on the outer surface of the workpiece to be spliced.

[0005] In some embodiments, the radial contact head includes a guide seat, a slider, an electric push rod, a disc spring assembly, a reading sleeve, and a contact shoe; the guide seat adopts a dovetail groove structure and is fixed to the inner ring plate surface of the corresponding ring frame, and the slider and the dovetail groove are clearance fit; the cylinder end of the electric push rod is connected to the rear side of the guide seat, the rod end of the electric push rod is connected to a pressure plate, the front of the pressure plate presses against the disc spring assembly, the front end of the disc spring assembly presses against the reading sleeve, and the reading sleeve is fixedly connected to the rear end of the contact shoe, forming a limited force contact chain that transmits force sequentially in the radial direction; the outer circle of the reading sleeve is engraved with circumferential lines, and a zero-position scale is fixed on the outer side of the guide seat.

[0006] In some embodiments, the radial contact heads located below the left positioning ring frame and the radial contact heads located below the right positioning ring frame have contact shoes with a roller-type structure; the outer circle of the roller is covered with a polyurethane layer, the roller is supported between the fork-shaped frames by bearings, and the rear end of the fork-shaped frames is fixed to the reading sleeve by a spherical washer; the radial contact heads located above, to the left and to the right of the left and right positioning ring frames have contact shoes with an arc-shaped pressure shoe structure; the front surface of the pressure shoe is covered with a polytetrafluoroethylene composite wear-resistant layer, and the pressure shoe is connected to the reading sleeve by a ball-head screw.

[0007] In some embodiments, a guide hole is provided on the right side of the left positioning ring frame and a guide bushing is installed. The contact rod passes through the guide bushing on the left positioning ring frame. A compression spring is sleeved on the rear end of the contact rod, and a limiting nut is provided behind the compression spring. The front end of the contact rod is a rounded contact, and the outer circle of the contact rod has a graduated sleeve. The axial push rod is a direct-push electric cylinder, and the end of the axial push rod is connected to a replaceable nylon pressure head. The gap inspection ruler includes a left overlapping piece, a middle bridge plate, and a right overlapping piece. The middle bridge plate is made of elastic steel sheet, and the left and right overlapping pieces are respectively fixed to both ends of the middle bridge plate. The lower surfaces of the left and right overlapping pieces are flush with the same plane.

[0008] A welding positioning method for assembling a storage tank includes: S1, perform initial zeroing by placing the workpiece to be spliced ​​inside the left and right positioning rings, keeping the radial contact head and axial push rod retracted, so that the lower radial contact head supports the workpiece. The contact start zone is the position range in which the radial contact head forms stable contact with the workpiece but has not yet established a significant additional clamping force. The holding zone is the position range in which the radial contact head establishes a controlled support force on the workpiece and the reading increment changes continuously and stably. Push the upper, left, and right radial contact heads to the contact start zone and record the readings. S2, perform single-piece roundness judgment, push the radial contact head to the middle of the holding band for the workpiece in the left and right positioning ring frames, compare the changes in readings in each position in the same ring frame and reduce the pushing depth in the position with the largest clearance. S3, perform docking and error classification, drive the right workpiece to move closer to the left workpiece and determine the source of error based on the pressure depth of the docking contact rod; S4, perform release check, keep the other azimuths stable, retract the radial contact head of the corrected azimuth to the contact start zone and then advance it again and compare the readings; S5, perform misalignment judgment and local correction, cross the seam inspection flat ruler and control the corresponding radial contact head to slightly retract according to the overlap state; S6 executes spot welding conformity control, controlling the radial contact head to retract or advance in the corresponding direction based on the pressure change of the contact rod after spot welding and the status of the inspection gauge.

[0009] In some embodiments, S2 includes: comparing the changes in readings in the left and right directions, the changes in readings in the top and bottom directions, and the total changes in the four directions within the same ring frame; when the changes in readings in the left and right directions are close and the change in the top reading is greater than the change in the bottom reading, it is determined that the workpiece to be spliced ​​has a tendency to flatten vertically; when the changes in readings in the left and right directions are asymmetrical, it is determined that the workpiece to be spliced ​​has a lateral eccentricity; when the total changes in each direction increase and the difference in direction is not prominent, it is determined that clamping induces diameter reduction; reducing the radial push depth according to the direction with the largest clearance, and balancing its opposite and adjacent directions of advancement.

[0010] In some embodiments, S3 includes: pushing the right workpiece with the axial push rod at the same length until the contact rod enters the pressure state and then stopping the uniform push; when the pressure on the upper contact rod is greater than that on the two lower contact rods, it is determined that the right workpiece has pitch tilt, the upper axial push is reduced, and the radial contact head above the right positioning ring frame is slightly retracted; when the pressure difference between the lower left and lower right contact rods is greater than a set threshold, it is determined that there is sway tilt, and the push balance of the left and right radial contact heads is corrected first.

[0011] In some embodiments, S4 includes: a preset value being a boundary threshold jointly determined by the device reading resolution, workpiece wall thickness, and allowable springback; when the reading compensation after the next advance is less than or equal to the preset value, it is determined that the previous correction eliminated the true geometric deviation; when the reading compensation after the next advance is greater than the preset value and the readings in adjacent directions change synchronously, it is determined that the previous correction included clamping-induced deformation, and in the next round of correction, the advance amount in the same direction is reduced and the opposing equalization amount is increased.

[0012] In some embodiments, S5 includes: when the left side of the seam inspection gauge overlaps smoothly and the right side is raised, it is determined that the outer surface of the workpiece on the right side is higher than the left side, and the radial contact head of the right positioning ring frame is slightly retracted while keeping the axial push rod in the same direction unchanged; when the left side of the seam inspection gauge is raised and the right side is smooth, the radial contact head of the left positioning ring frame is slightly retracted; when the seam inspection gauge shows repeated behavior when checked multiple times in the same direction, it is determined that there is local board edge wavy, and the correction amplitude of that direction is reduced individually, and the correction amount is shared by two adjacent directions.

[0013] In some embodiments, S6 includes: after spot welding at the top, if the pressure on the upper contact rod increases and the pressure change of the lower contact rod is less than or equal to a threshold, it is determined that heat shrinkage pulls the seam edge together in the upward direction, the upper radial contact head is retracted, and the holding band corresponding to the lower radial contact head remains unchanged; after spot welding at the lower left, if the seam inspection gauge shows an enhanced trend of right-high and left-low, the corresponding radial contact head on the right is pushed in with additional amount; The method also includes S7, which performs mutation identification and sequence protection. If the reading of any upper or side radial contact head suddenly increases and the reading of the opposite radial contact head does not change synchronously, and the contact rod jumps under pressure, it is determined that the workpiece to be spliced ​​has not been completely settled. All axial push rods are controlled to stop advancing, the upper radial contact head retracts to the contact start zone, and the lower radial contact head remains supported. After the reading returns to a stable state, it enters the holding zone again.

[0014] The present invention has the following beneficial effects: 1. This invention arranges radial contact heads with disc spring assemblies and reading sleeves around the inner circumference of the positioning ring frame, forming a finite force contact chain that transmits force radially. Combined with a single-piece roundness identification and release verification method, the radial contact heads with corrected orientation are retracted and then advanced again for comparison reading, solving the problem of multi-source error coupling caused by excessive reliance on rigid locking in the background technology. Its beneficial effect is that it can accurately separate the actual geometric deviation of the workpiece to be spliced ​​from the temporary elastic deformation induced by clamping, avoiding uncontrollable springback caused by forced correction of local geometric contours, and improving assembly accuracy. 2. This invention, through the setting of a mating contact rod, an axial push rod, and a gap inspection gauge, combined with a method for classifying butt joint approach errors and controlling spot welding compliance, dynamically controls the radial contact head to finely adjust its retraction or advancement based on the pressure changes of the mating contact rod and the state of the gap inspection gauge after spot welding. This design overcomes the shortcomings of existing rigid tooling that cannot adapt to the microscopic displacement caused by the thermal shrinkage of spot welding. Its beneficial effects are that it can provide multi-directional adaptive adjustment, effectively release the thermal shrinkage stress and displacement caused by spot welding, avoid repeated excessive misalignment and local wave deformation, and ensure the quality of adaptive mating assembly. Attached Figure Description

[0015] Figure 1This is a schematic diagram of the overall external structure of the device; Figure 2 This is a structural schematic diagram of the left positioning ring frame; Figure 3 This is a structural schematic diagram of the right positioning ring frame; Figure 4 This is a schematic diagram of the guide seat structure; Figure 5 The flowchart illustrates the logic control of the method provided in this embodiment of the invention.

[0016] In the diagram: 1. Base; 2. Left positioning ring frame; 3. Right positioning ring frame; 21. Radial contact head above the left positioning ring frame; 22. Radial contact head on the left side of the left positioning ring frame; 23. Radial contact head on the right side of the left positioning ring frame; 24. Radial contact head below the left positioning ring frame; 25. Radial contact head above the right positioning ring frame; 26. Radial contact head on the left side of the right positioning ring frame; 27. Radial contact head on the right side of the right positioning ring frame; 28. Radial contact head below the right positioning ring frame; 4. Alignment contact rod; 5. Axial push rod; 6. Gap inspection straightener; 211. Guide seat; 212. Dovetail groove structure; 213. 214. Slider; 215. Electric actuator; 216. Disc spring assembly; 217. Reading sleeve; 218. Contact shoe; 219. Roller structure; 220. Polyurethane layer; 221. Fork frame; 222. Bearing; 223. Spherical washer; 224. Arc-shaped pressure shoe structure; 225. Polytetrafluoroethylene composite wear-resistant layer; 226. Ball head screw; 31. Guide bushing; 32. Compression spring; 33. Limit nut; 34. Rounded corner contact; 35. Marked sleeve; 36. Direct push electric cylinder; 37. Replaceable nylon pressure head; 38. Left overlapping piece; 39. Middle bridge plate; 40. Right overlapping piece; 41. Elastic steel sheet. Detailed Implementation

[0017] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0018] Example 1: like Figure 1 As shown, a welding positioning device for assembling a storage tank includes: Base 1, left positioning ring frame 2, right positioning ring frame 3, aligning contact rod 4, axial push rod 5, gap inspection ruler 6, and control unit; The control unit is communicatively connected to the radial contact head, the axial push rod, and the gap inspection ruler; the base 1 is a rectangular welded bed. The left positioning ring frame 2 and the right positioning ring frame 3 are both vertically fixed above the base 1, parallel to each other and with their center lines coplanar. The left positioning ring frame 2 is fixed to the left side of the base 1, and the right positioning ring frame 3 can be adjusted and locked along the length of the base 1. like Figure 2 As shown, radial contact heads 21, 22, 23, and 24 are respectively arranged above, to the left, to the right, and below the inner circumference of the left positioning ring frame 2. like Figure 3 As shown, radial contact head 25, radial contact head 26, radial contact head 27, and radial contact head 28 are arranged on the inner circumference of the right positioning ring frame 3. The contact rod 4 is arranged on the right side of the left positioning ring frame 2, located at the top, lower left and lower right and spaced equally apart, with its front end facing the splicing seam of the workpiece to be spliced; The axial push rod 5 is arranged on the left side of the right positioning ring frame 3, and is arranged in a corresponding position to the contact rod 4, and contacts the end face of the workpiece to be spliced. Place a 6-span seam gauge on both sides of the seam on the outer surface of the workpiece to be spliced.

[0019] The base 1 is configured as a rectangular welded bed with length and width directions, which is used to support the left positioning ring frame 2 and the right positioning ring frame 3 and provide a common mounting reference. The left positioning ring frame 2 is fixed on one side of the base 1 and used as a reference side support. The right positioning ring frame 3 is installed on the other side of the base 1 and moves along the length of the base 1 through an adjustable connection structure to adapt to cylinder sections or heads with different axial dimensions. The adjustable connection structure includes a linear sliding guide rail parallel to the base 1, and a screw nut drive mechanism that drives the right positioning ring frame 3 to move along the linear sliding guide rail and can achieve position self-locking; the two positioning ring frames keep parallel front and rear and their center lines are coplanar, so that the workpieces to be spliced ​​have a unified theoretical axis of passage during the axial approach process; Each positioning ring frame has four radial contact heads on its inner circumference. The arrangement of the heads on the top, left, right, and bottom allows the workpiece to have adjustable contact conditions in both vertical and horizontal directions. The bottom radial contact head provides support, while the top and side radial contact heads provide posture correction and stabilization. Three matching contact rods 4 are set on the right side of the left positioning ring frame 2. The three matching contact rods 4 face the splicing seam and are distributed on the top, lower left, and lower right sides. They are used to detect the pressure state when the seam edges of the two workpieces to be spliced ​​are close together. Three axial push rods 5 are set on the left side of the right positioning ring frame 3. The three axial push rods 5 correspond one-to-one with three matching contact rods 4. After the axial push rods 5 contact the end face of the workpiece to be spliced ​​on the right, they apply force along the axial direction to push the workpiece to be spliced ​​on the right closer to the workpiece to be spliced ​​on the left. The seam inspection ruler 6 is manually placed across the outer surface of both sides of the splice seam to determine whether the local misalignment is due to the material on the left or the material on the right being too high. The above structure allows radial roundness, axial alignment and misalignment judgment to be handled by different components, which can separate the roundness error, axial clearance error and seam height error and reduce misjudgment caused by single rigid clamping.

[0020] like Figure 4 As shown, the radial contact head includes a guide seat 211, a slider 213, an electric push rod 214, a disc spring assembly 215, a reading sleeve 216, and a contact shoe 217; the guide seat 211 adopts a dovetail groove structure 212 and is fixed on the inner ring plate surface of the corresponding ring frame, and the slider 213 and the dovetail groove are in clearance fit. The cylinder end of the electric push rod 214 is connected to the rear side of the guide seat 211. The rod end of the electric push rod 214 is connected to the pressure plate. The front of the pressure plate presses against the disc spring assembly 215. The front end of the disc spring assembly 215 presses against the reading sleeve 216. The reading sleeve 216 is fixedly connected to the rear end of the contact shoe 217, forming a limited force contact chain that transmits force in the radial direction. The outer circle of the reading sleeve 216 is engraved with circumferential lines. A zero-position scale is fixed on the outside of the guide seat 211.

[0021] The radial contact head is set on the inner ring plate of the positioning ring frame. Its core purpose is not to form a rigid lock, but to establish a repeatable force range after the workpiece contacts. The guide seat 211 adopts a dovetail groove structure 212 extending along the radial direction of the ring frame. A predetermined gap is maintained between the dovetail groove and the slider 213, so that the slider 213 has both guiding accuracy and avoids jamming caused by splashing, dust or thermal deformation when moving radially. The cylinder end of the electric push rod 214 is hinged or pinned to the rear side of the guide seat 211. The rod end is connected to the pressure plate. The front end of the pressure plate acts on the disc spring assembly 215, the reading sleeve 216 and the contact shoe 217 in sequence, forming a series force transmission path from the driving component to the contact component. The disc spring assembly 215 is used to limit the gradient of contact force change after pushing in, so that the contact shoe 217 enters a limited force contact state after contacting the workpiece; the limited force contact chain is configured such that when the pushing amount increases, the additional contact force increment of the contact shoe 217 on the workpiece is constrained by the compression characteristics of the disc spring, so that the reading change can more stably reflect the workpiece clearance amount, rather than reflecting the deformation of the rigid transmission chain itself; the outer circle of the reading sleeve 216 is provided with continuous circumferential lines, and the outer side of the guide seat 211 is provided with a zero-position scale. The operator or control unit obtains the state information of the contact shoe 217 from no contact, initial contact to stable contact by reading the position change of the lines relative to the zero-position scale; To address the problem that purely mechanical engraving is insufficient to support the control unit in high-frequency, high-precision micro-step data acquisition, in this embodiment, the circumferential engraving groove of the reading sleeve 216 can be filled with highly reflective material, and a photoelectric reading component is integrated next to the zero-position scale on the outside of the guide seat 211. The control unit uses this component to capture the optical displacement change of the scale line relative to the ruler in real time, thereby converting the mechanical displacement into a continuous digital signal that supports high-frequency sampling. This ensures that the large amount of micro-step displacement data required by the subsequent initial contact recognition unit and holding validity recognition unit can be truly acquired, avoiding the mismatch between the hardware sensor acquisition capability and the software high-dimensional computing requirements. The technical advantage of this structure is that the determination of the contact point no longer depends on the operator's feel, and the holding state no longer depends entirely on the absolute stroke of the electric push rod 214. Therefore, it can provide a consistent reading basis for subsequent error decomposition and release review. Both the contact start band and the holding band are divided based on the single push process of the same radial contact head. Specifically, the radial contact head is first advanced from its retracted position completely away from the workpiece. When the reading sleeve 216 first shows a continuous, non-random displacement change relative to the zero scale, and this displacement change does not disappear due to mechanical backlash as it continues to advance in small steps, the reading at that moment is recorded as the initial contact reference. A small reading range covering the initial contact reference to absorb the effects of mechanical backlash and surface roughness is defined as the contact initiation zone. The physical meaning of the contact initiation zone is that the contact shoe 217 has formed a stable contact with the workpiece but has not yet established a significant additional clamping force. Continue advancing in fixed small steps. When the reading increases continuously and the reading increment corresponding to the unit advance enters the main working area of ​​the disc spring group 215, and the fluctuation of two adjacent readings remains within the allowable range of the device resolution, the stable reading interval is defined as the holding band. The physical meaning of the holding band is that the contact shoe 217 has established a repeatable finite support force on the workpiece, which can maintain the posture and will not dominate the elastic deformation of the workpiece due to excessive pushing force. The inputs for determining the contact start zone are the displacement of the electric push rod 214, the reading of the scale on the reading sleeve 216, and whether a continuous contact signal appears; the inputs for determining the holding zone are the continuity and fluctuation amplitude of the reading after further advancement based on the contact start zone; thus, entering the contact start zone in subsequent steps is used to establish a unified zero point, and entering the holding zone is used to establish a repeatable clamping state. The two serve as prerequisites for zeroing judgment and attitude correction judgment, respectively; the contact start zone and the holding zone can be understood as a two-level judgment model in the same contact process, where the first-level judgment is used to answer whether a real contact has been formed, and the second-level judgment is used to answer whether repeatable holding has been entered. The two-level judgment model logically includes a retraction baseline confirmation unit, an initial contact recognition unit, and a holding validity recognition unit. The retraction baseline confirmation unit uses the zero-position scale correspondence when the contact head is completely separated from the workpiece as the initial reference. The initial contact recognition unit receives the changes in the scale displacement during the subsequent micro-step advancement, excludes occasional changes caused by single jumps, mechanical backlash compensation, or extrusion of contaminant particles, and only outputs the judgment of entering the contact start zone when the displacement change is continuously maintained. After the previous stage output is established, the holding validity recognition unit continues to receive the advancement step length, reading increment, and adjacent sampling fluctuations. Only when the reading change enters the main working area of ​​the disc spring group 215 and the fluctuation is controlled, does it output the judgment of entering the holding zone. The physical relationship represented by this judgment model is as follows: the advancement of the electric push rod 214 first eliminates the transmission gap, and then forms surface contact between the contact shoe 217 and the workpiece. The disc spring assembly 215 converts the further advancement into a limited increase in contact force. Therefore, when the reading transitions from the no-contact stage and the initial contact stage to the limited force holding stage, it reflects the continuous causal process of the workpiece surface being touched, slight retraction, and the establishment of controlled support. Thus, the graduation line of the reading sleeve 216 does not simply record the nominal stroke of the electric push rod 214, but through the series relationship of the guide, elastic element, and contact element, it transforms the physical process of mechanical advancement—contact establishment—limited force support into discernible state information. To ensure the reproducibility of the above two-level judgment model in a real industrial environment, this embodiment also discloses in detail the on-site calibration steps during system deployment: After the initial deployment or replacement of the disc spring assembly 215, no-load calibration needs to be performed in a workpiece-free state, recording the noise sequence of the base displacement of the reading sleeve 216 during the process of the electric push rod 214 advancing from the zero position to the full scale, and extracting its maximum fluctuation amplitude as the characteristic baseline of mechanical idle stroke and frictional resistance; using a standard rigid ring to replace the real workpiece for loading calibration, advancing the radial contact head in a fixed small step size, and collecting the displacement increment data of the reading sleeve 216 relative to the zero-position scale; The displacement increment is compared with the theoretical propulsion to establish a mapping relationship from no contact to finite force stability. Among them, the initial contact identification unit multiplies the maximum fluctuation amplitude extracted from the no-load calibration by the reliability coefficient as the threshold for filtering occasional changes. The stability effectiveness identification unit sets the judgment boundary of the main working area of ​​disc spring group 215 according to the inflection point of the reading increment entering the linear stability region in the rigid ring loading calibration. Through the above calibration, the abstract judgment logic is strongly bound to the specific mechanical assembly characteristics and sensor background noise, avoiding the generalization failure of the algorithm across different equipment sets; since the dovetail groove of the guide seat 211 and the slider 213 retain a predetermined gap, the slider 213 will inevitably wobble slightly during the advancement of the electric push rod 214, resulting in off-center load frictional resistance, which causes the output force of the electric push rod 214 to not be completely converted into the compressive force of the disc spring assembly 215; in order to overcome this dynamic interference factor, this embodiment further introduces friction compensation logic in the stability effectiveness identification unit; The pushing process is structurally decomposed into three force-bearing stages: the idle stage, the friction pressure-building stage, and the effective contact stage; the total output force of the push rod is defined as... The effective compression force of the disc spring is The frictional force of slider 213 under eccentric loading is In the no-load calibration, the frictional resistance baseline at different propulsion speeds is extracted, and this frictional resistance baseline is set as follows: During actual contact, the system calculates in real time the theoretical disc spring force corresponding to the current reading increment. If the current feedback value of the push rod motor is used to calculate... With theory The difference exceeds the baseline of the calibrated frictional resistance. If so, it is determined that slider 213 is stuck or wobbling; At this time, the system controls the electric push rod 214 to perform a micro-retract-re-advance jittering action to release the accumulated static off-center friction, so that... The force is reduced back to the dynamic friction level. Through this logical decomposition and action response of the physical state, it is ensured that the reading of the holding band truly reflects the controlled support force of the workpiece, avoiding force transmission distortion caused by guide rail clearance. In the above friction compensation logic, the specific data flow and processing method is as follows: the control unit reads the real-time current feedback value of the push rod motor through the servo driver, multiplies the current value by the motor torque constant, the transmission mechanism reduction ratio, and the lead screw lead conversion coefficient, and calculates the current total output force. ; Simultaneously, the control unit reads the real-time displacement increment output by the photoelectric reading component and, combined with the calibration stiffness curve of the disc spring assembly 215, calculates the theoretical effective compressive force of the disc spring. The comparison module inside the control unit calculates the difference between the two in real time and compares it with the speed-friction baseline mapping table stored in the memory. If the difference exceeds the friction baseline threshold at the corresponding propulsion speed, the control unit sends a micro-retreat-re-advance command sequence containing a predetermined number of pulses to the servo driver.

[0022] The radial contact head 24 located below the left positioning ring frame 2 and the radial contact head 28 located below the right positioning ring frame 3 have contact shoes 217 with a roller-type structure 218. The outer circle of the roller is covered with a polyurethane layer 219. The roller is supported between the fork-shaped frames 220 by bearings 221. The rear end of the fork-shaped frame 220 is fixed to the reading sleeve 216 by a spherical washer 222. The radial contact heads located above, to the left and to the right of the left positioning ring frame 2 and the right positioning ring frame 3 have contact shoes 217 with an arc-shaped pressure shoe structure 223. The front surface of the pressure shoe is covered with a polytetrafluoroethylene composite wear-resistant layer 224. The pressure shoe is connected to the reading sleeve 216 by a ball head screw 225.

[0023] The contact shoe 217 of the lower radial contact head is configured as a roller-type structure 218. The roller is installed between the fork-shaped frames 220 through bearings 221, allowing the workpiece to undergo slight circumferential rolling or self-positioning under the supported state. A polyurethane layer 219 is provided on the outer circle of the roller. The polyurethane layer 219 reduces the risk of indentation on the outer surface of the thin-walled workpiece and improves the stability of the support contact through moderate surface flexibility. The rear end of the fork-shaped frame 220 is connected to the reading sleeve 216 through a spherical washer 222. The spherical washer 222 is used to absorb the small angular deviation caused by the local curvature fluctuation of the workpiece and avoid the formation of additional load when the roller axis is inconsistent with the local tangent direction of the workpiece. The contact shoes 217 of the radial contact heads on the top, left and right sides are set as arc-shaped pressure shoe structures 223. The front surface of the pressure shoe is covered with a polytetrafluoroethylene composite wear-resistant layer 224 to reduce friction fluctuations on the contact surface and reduce sudden changes in dry friction caused by welding environment pollution. The pressure shoe is connected to the reading sleeve 216 by a ball head screw 225. The ball head connection allows the pressure shoe to swing within a predetermined angle range, thereby automatically conforming to the local tangent direction of the outer circle of the workpiece. The roller-type lower support and the curved pressure shoe-type lateral support have different functional divisions: the lower support provides low-hysteresis support conditions, and the lateral support provides directional attitude constraints; this combination enables the changes in the readings on the upper, left and right sides to mainly correspond to the actual geometric clearance of the workpiece, rather than to the false changes caused by bottom friction lock-up or pressure shoe off-center loading.

[0024] A guide hole is provided on the right side of the left positioning ring frame 2 and a guide bushing 31 is installed. The contact rod 4 passes through the guide bushing 31 on the left positioning ring frame 2. A compression spring 32 is sleeved at the rear end of the contact rod 4. A limit nut 33 is provided behind the compression spring 32. The front end of the contact rod 4 is a rounded contact 34. The outer circle of the contact rod 4 is equipped with a scribed sleeve 35. The axial push rod 5 adopts a direct push electric cylinder 36. The rod end of the axial push rod 5 is connected to a replaceable nylon pressure head 37. The gap inspection flat ruler 6 includes a left overlapping piece 38, a middle bridge plate 39, and a right overlapping piece 40. The middle bridge plate 39 adopts an elastic steel sheet 41. The left overlapping piece 38 and the right overlapping piece 40 are respectively fixed to both ends of the middle bridge plate 39. The lower surfaces of the left overlapping piece 38 and the right overlapping piece 40 are flush with the same plane.

[0025] The contact rod 4 passes axially through the guide bushing 31 on the left positioning ring frame 2. The guide bushing 31 is used to limit the radial swing of the contact rod and keep the contact aligned with the edge area of ​​the splice seam. A compression spring 32 is provided at the rear end of the contact rod 4. The front end of the compression spring 32 abuts against the shoulder of the guide bushing 31, and the rear end is limited by the limiting nut 33. The function of the compression spring 32 is to make the contact rod generate a recoverable displacement when it is pressed by the seam edge. The displacement of the scribed sleeve 35 relative to the reference line of the ring frame constitutes the pressure depth display. The front end of the contact rod is equipped with a rounded contact 34. The rounded transition can reduce local crushing on the edge of the workpiece and reduce the snagging caused by edge burrs. The axial push rod 5 adopts the form of a direct push electric cylinder to obtain controllable push amount and repeatable stopping accuracy. The nylon pressure head connected to the rod end is a replaceable part to adapt to different workpiece end surface roughness and prevent metal hard contact crushing. The seam inspection ruler 6 consists of a left overlapping piece 38, a middle bridge plate 39, and a right overlapping piece 40. The bottom surfaces of the left overlapping piece 38 and the right overlapping piece 40 are on the same plane. The middle bridge plate 39 uses an elastic steel sheet 41, so that the inspection ruler can serve as a plane reference while allowing limited flexible deformation when crossing seams. The technical significance of this combination structure is that the contact rod 4 outputs the pressure information of the seam edge approaching, the axial push rod 5 provides the axial test force in the corresponding direction, and the seam inspection ruler 6 provides the height direction information of the seam edge. The three correspond to the gap change, posture change, and misalignment change, respectively, so that the subsequent correction action has a clear basis.

[0026] Example 2: like Figure 5 As shown, a welding positioning method for assembling a storage tank includes: S1, perform initial zeroing by placing the workpiece to be spliced ​​inside the left positioning ring 2 and the right positioning ring 3, keeping the radial contact head and axial push rod 5 retracted, so that the lower radial contact head supports the workpiece. The contact start zone is the position range in which the radial contact head and the workpiece form stable contact but have not yet established a significant additional clamping force. The holding zone is the position range in which the radial contact head establishes a controlled support force on the workpiece and the reading increment changes continuously and stably. Push the upper, left, and right radial contact heads to the contact start zone and record the readings. S2, perform single-piece roundness judgment, push the radial contact head to the middle of the holding band for the workpiece in the left positioning ring 2 and right positioning ring 3, compare the changes in readings in each position in the same ring and reduce the pushing depth in the position with the largest clearance; S3, perform docking and error classification, drive the right workpiece to move closer to the left workpiece and determine the source of error based on the pressure depth of the docking contact rod 4; S4, perform release check, keep the other azimuths stable, retract the radial contact head of the corrected azimuth to the contact start zone and then advance it again and compare the readings; S5, perform misalignment judgment and local correction, cross the seam inspection flat ruler 6 and control the corresponding radial contact head to slightly retreat according to the overlap state; S6 executes spot welding conformity control, and controls the radial contact head to retract or advance according to the pressure change of the contact rod 4 after spot welding and the status of the inspection gauge 6.

[0027] This method is used for connecting cylindrical sections or connecting end caps to cylindrical sections; in S1, the left and right workpieces to be spliced ​​are placed in the left positioning ring 2 and the right positioning ring 3 respectively, and all axial push rods 5 and the upper and lateral radial contact heads are kept in a retracted state, with only the lower radial contact head in contact with the workpiece's own weight; the upper, left and right radial contact heads are slowly advanced until their respective reading sleeves 216 enter the contact start zone and the reading is recorded; In S2, the radial contact heads in each direction are pushed to the middle of the holding band. The changes in readings in each direction within the same positioning ring frame are compared. The pushing depth is reduced in the direction with the largest clearance, and the opposing or adjacent directions are balanced and corrected to reduce the roundness distortion of individual parts. In S3, the three axial push rods 5 push the right workpiece closer to the left workpiece with a set step size. After any of the paired contact rods 4 enters the pressure state, the unified push stops. The error is mainly determined by the distribution of the pressure depth of the three paired contact rods 4, which comes from the overall gap, pitch tilt or yaw tilt. In S4, the radial contact head with the corrected orientation is retracted to the vicinity of the contact start zone and then pushed back to the holding zone. The difference in readings before and after the retraction and after the push is compared to identify the proportion of the actual geometric deviation and the clamping-induced deformation in the orientation correction. In S5, the operator places the seam inspection ruler 6 across the outer surfaces of both sides of the splice seam, determines the direction of local misalignment by the fit of the left overlapping piece 38 and the right overlapping piece 40, and controls the radial contact head in the corresponding position to make a slight retraction. In S6, during the spot welding process, the pressure change of the mating contact rod 4 and the height change of the seam edge displayed by the seam inspection ruler 6 are continuously observed. The radial contact head in the corresponding position is retracted or advanced to release the welding heat shrinkage while maintaining the overall mating relationship. The implementation logic of this method is to first form repeatable contact conditions, and then deal with the single part shape error, the docking posture error and the spot welding heat drift error respectively, thereby reducing the risk of processing deviation caused by the superposition of multiple source errors.

[0028] S2 includes: comparing the changes in readings in the left and right directions, the changes in readings in the top and bottom directions, and the total changes in the four directions within the same ring frame; when the changes in readings in the left and right directions are close and the changes in the top reading are greater than the changes in the bottom reading, it is determined that the workpiece to be spliced ​​has a tendency to flatten vertically; when the changes in readings in the left and right directions are asymmetrical, it is determined that the workpiece to be spliced ​​has a lateral eccentricity; when the total changes in each direction increase and the difference in direction is not prominent, it is determined that the clamping induces a reduction in diameter; the radial pushing depth is reduced according to the direction with the largest clearance, and the advancement in the opposite and adjacent directions is balanced.

[0029] The S2 judgment is based on multi-directional comparison under the same workpiece, the same positioning ring frame, and the same contact state. The change in readings in each direction is obtained by subtracting the contact start zone reading from the holding zone reading. The larger the change in readings, the more obvious the yielding is under the same pushing conditions in that direction. If the difference in readings between the left and right directions is within the first set range, and the difference in readings between the upper and lower directions is greater than the second set threshold, it can be determined that the workpiece has a flattening trend in the vertical direction. This is because the upper part is more likely to yield inward, while the lower part is more restricted by its own weight and support. At this time, the upper radial contact head is controlled to reduce the pushing depth, and small, balanced pushing is made on the left and right sides or the lower part to reduce the flattening of the upper part. If the changes in readings on the left and right sides are asymmetrical, it indicates that the workpiece is laterally eccentric or the elliptical main axis is deflected. Control the side with the larger clearance to retreat by a preset step size, and add a predetermined advance amount to the side with the smaller clearance to make the lateral force more balanced. If the total change in all four directions increases but the difference in direction is not prominent, it indicates that the workpiece is being clamped and its diameter is reduced. In this case, do not continue to increase the advance amount in all directions, but retreat together to a lower holding level to re-establish contact. The key point of this implementation method is that the single-piece roundness finding does not pursue absolute consistency of all readings, but uses the difference in clearance in each direction to identify the deformation trend of the workpiece body and the deformation trend induced by clamping, and then achieves lower stress correction by reducing the push depth of the direction with the largest clearance.

[0030] S3 includes: axial push rod 5 pushes the right workpiece in phase until the contact rod 4 enters the pressure state and then stops the uniform push; when the pressure on the upper contact rod 4 is greater than that on the two lower contact rods 4, it is determined that the right workpiece has pitch tilt, the upper axial push is reduced, and the radial contact head above the right positioning ring frame 3 is slightly retracted; when the pressure difference between the lower left and lower right contact rods 4 is greater than the set threshold, it is determined that there is sway tilt, and the push balance of the left and right radial contact heads is corrected first.

[0031] In S3, the three axial push rods 5 advance in parallel to ensure consistent testing conditions during the initial approach. When any of the mating contact rods 4 begins to be pressed, it indicates that the right workpiece has formed a partial seam with the left workpiece. At this point, the unified advancement stops, and the pressure distribution judgment is entered. If the pressure depth of the upper mating contact rod 4 is higher than that of the two lower mating contact rods 4, it indicates that the upper edge closes first while the lower edge still has a gap, and it can be determined that the right workpiece has a pitch tilt. The corresponding correction method is to reduce the subsequent advancement of the upper axial push rod 5 and control the radial contact head above the right positioning ring frame 3 to slightly retract, so that the upper edge releases part of the pre-pressure and promotes the lower edge to continue to approach. If there is a significant difference in the pressure on the lower left and lower right contact rods 4, it indicates that the workpiece on the right side is tilted. Simply increasing the axial thrust on one side will increase the risk of local collision. Therefore, we should first adjust the pushing balance of the left and right radial contact heads to correct the lateral posture of the workpiece axis before restoring the axial approach. The threshold value is a limit value calculated based on the allowable limit tolerance of the contact rod under pressure and the maximum deflection angle required by the assembly process. In this embodiment, the axial push rod 5 is not only used for feeding, but also for classifying the source of error through pressure feedback. Whether the contact rod 4 in the same direction actually absorbs the feeding amount in that direction directly determines whether the correction action should be applied to axial propulsion or radial attitude adjustment.

[0032] S4 includes: the preset value is a limit threshold determined by the device reading resolution, workpiece wall thickness and allowable springback amount; when the reading compensation after the next advance is less than or equal to the preset value, it is determined that the previous correction eliminated the true geometric deviation; when the reading compensation after the next advance is greater than the preset value and the readings in adjacent directions change synchronously, it is determined that the previous correction included clamping-induced deformation, and the advance amount in the same direction is reduced and the opposing balance amount is increased in the next round of correction.

[0033] The release check in S4 is used to distinguish between true geometric deviation and clamping-induced deformation; for a certain azimuth that has been corrected, the remaining azimuths are kept in a stable state, and the radial contact head of that azimuth is only retracted to the vicinity of the contact starting zone, so that the contact force in that direction is reduced to a low level; within the system cycle, the azimuth is advanced to the original stable zone position again, and the reading compensation amount required to reach the stable state twice is compared. If the reading compensation after the next advance is less than the preset value, it means that the workpiece did not experience a reverse springback greater than the set tolerance during the retraction process. The previous correction mainly offset the original geometric deviation, and this direction can be finely adjusted again with a smaller correction range. If the reading compensation after the next advance is greater than the preset value, and the readings in adjacent directions change synchronously in the same direction, it means that a springback deformation exceeding the preset threshold occurred in this direction during the retraction. It is determined that the clamping-induced deformation included in the previous correction exceeds the set proportion. In the next round of correction, the advance amount in the same direction should be reduced, and the correction amount should be shared through the balancing effect of opposite or adjacent directions. The preset value can be determined by the device reading resolution, workpiece wall thickness and allowable springback amount. The technical effect of this implementation is that the correction result is not judged by the single contact state as the final value, but by the repeatability after release as the criterion, thereby reducing the probability of misjudging transient stress deformation as permanent geometric deviation. The reading compensation after re-advancement refers to the difference between the reading when the original holding zone reference position is reached before retreating in the same azimuth and the reading when the original holding zone reference position is reached again after retreating; its input sources include the holding zone reference reading before retreating in that azimuth, the reading near the starting zone after retreating, and the re-measured reading when advancing back to the original holding zone. The specific processing procedure is as follows: First, record the reference reading of the holding zone at the azimuth when the correction is completed; then, retreat the azimuth to the vicinity of the starting zone and wait for a short period of stabilization; advance again with the same small step size as the first correction until the reading re-enters the target range corresponding to the original holding zone; compare the difference in readings required to compensate when the target range is reached twice, and simultaneously observe whether the readings of adjacent azimuths show the same direction of linkage. The preset value here is not an isolated constant, but a discrimination boundary used to distinguish between acceptable natural springback and clamping springback that requires reallocation of correction amount. The preferred method for determining it is: first, take the device reading resolution as the lowest identification unit, and then combine the elastic sensitivity corresponding to the workpiece wall thickness and the allowable springback amount of the process to select a numerical range that is greater than the reading noise and less than the allowable misalignment correction allowance as the preset value. Therefore, when the reading compensation does not exceed the limit, the system interprets the change as a normal repeatability error; when the reading compensation exceeds the limit and is accompanied by linkage with adjacent azimuths, the system interprets it as a real rebound after clamp release, and triggers the next round of correction decisions to reduce the advance in this azimuth and increase the balance of opposing or adjacent azimuths. The aforementioned release review can be understood as a set of discrimination logic targeting the source of correction. Its purpose is not to find the circle again, but to identify what proportion of the previous correction came from the geometric deviation of the workpiece body and what proportion came from the transient deformation of the clamping. The discrimination logic includes a reference holding part, a single-direction release part, and a linkage observation part in structure: the reference holding part establishes a relatively stable external constraint condition by keeping the other directions stable; the single-direction release part observes whether there is independent springback in the corrected direction by releasing the contact force only in the corrected direction; the linkage observation part judges whether the springback is a local real return or a systemic change caused by the redistribution of the entire force ring by comparing whether the adjacent directions change synchronously. Its data flow is as follows: first, input the reference reading before retraction, then input the low contact reading after retraction, input the retest reading when pushing back to the original target interval and the synchronous reading of adjacent positions; the discrimination unit first compares the difference before and after in this position, and then combines whether the adjacent positions are linked in the same direction to give a conclusion that geometric deviation is dominant or clamping deformation is dominant; the physical relationship represented by this logic is: if the previous correction mainly eliminated the original shape error of the workpiece, then the workpiece will not obviously reverse and recover after reducing the contact force, so the re-pushing compensation is small; if the previous correction mainly relied on external force to form, then after the contact force is released, the material will rebound according to its own elastic trend, and this rebound will affect the readings of adjacent support points to change in the same direction; Therefore, only by observing the compensation difference in this azimuth together with the adjacent azimuth can we avoid simply attributing changes in a single reading to geometric errors or operational noise. To ensure the reliable implementation of the above-mentioned release review logic in a real industrial environment, this embodiment further discloses the on-site calibration steps and data acquisition of the preset value: Before mass production, sample specimens with representative wall thickness and material are taken and clamping and release tests are performed at a real welding station. By arranging a strain gauge matrix on the inner wall of the specimen, the actual elastic deformation data of the specimen surface during the advance and retraction of the contact shoe 217 and the reading compensation data of the reading sleeve 216 are collected simultaneously; the elastic deformation recovery amount reflected by the strain gauge matrix is ​​matched with the reading compensation amount to eliminate the systematic error caused by the transmission gap of the device itself. During the calibration process, the maximum value of the reading compensation when the stress of the specimen does not exceed the yield limit and is fully recovered after the thrust is removed is taken as the upper limit of the calibration for clamping-induced deformation; the range of readings when the device is repeatedly positioned under no-load conditions is taken as the lower limit of the calibration; the final preset value is selected between the upper and lower limits of the calibration. This calibration step establishes a clear numerical mapping relationship between the abstract preset value in the logical judgment and the real physical springback characteristics of the workpiece of a specific material, ensuring that the algorithm is not only theoretically feasible in the industrial field, but also has anti-interference ability and high reproducibility for specific workpieces. In a multi-point clamping physical environment, the workpiece is in a statically indeterminate constraint state. When the single-direction release part releases only the radial contact head in a certain direction, the support reaction force in the other holding directions will be redistributed. This causes the springback amount in the release direction to not only include its own local elastic recovery, but also the interference of the overall forced displacement of the workpiece. In order to isolate this coupling interference, the linkage observation part introduces a quantitative calculation logic based on geometric coordination. Let the radial readings of adjacent azimuths j and k be respectively and The system is based on and Calculate its equivalent translational displacement component in the azimuth direction i. Where i is the specified release orientation; the specific quantification calculation logic is as follows: since the four radial contact heads above, below, left and right are orthogonally distributed, when the release orientation i is released, its opposite orientation remains stable, and the radial axes of adjacent orientations j and k are perpendicular to the movement direction of orientation i. If the workpiece experiences pure local elastic rebound, the radial readings of adjacent orientations j and k should remain essentially unchanged; if the workpiece undergoes a rigid body translation to the left after being released from the left side, the center of the workpiece will shift to the left, causing the upper and lower contact shoes 217 to extend inward to maintain contact; based on the approximate relationship of the chord height of the circle, assuming the workpiece radius is R, when the lateral translation of the center of the circle is D, the radial displacement increment generated in the vertical direction is approximately the square of D divided by twice the workpiece radius R. Therefore, the system extracts the average radial reading change of adjacent azimuths j and k as the vertical displacement increment, and solves for the lateral translation D, which is the equivalent translational displacement component. Let the total rebound reading compensation for azimuth i be... The total rebound reading compensation amount for azimuth i Subtract the equivalent translational displacement component The pure local elastic rebound amount after removing the overall displacement interference is obtained. ; Only when Only when the value exceeds the preset value is it finally determined that the previous correction contained a lot of clamping-induced deformation; through this structured geometric projection decomposition, the internal judgment mechanism under multi-point coupled force environment is clarified, ensuring the accuracy of the release review logic under complex working conditions; in the execution process of the above release review logic, the system's data flow and interaction mechanism is as follows: the reference holding part, the single-direction release part, and the linkage observation part run as software sub-modules in the main control computer of the control unit; The photoelectric reading components of the radial contact heads in each direction transmit continuous displacement signals to the main control computer in real time via the industrial fieldbus; the single-direction release part sends a retraction command to the electric push rod 214 controller in the corresponding direction and simultaneously triggers the linkage observation part to open the high-frequency data buffer; the linkage observation part extracts the reading changes of adjacent directions before and after release from the buffer, substitutes them into the aforementioned chord height approximation relationship to calculate the equivalent translational displacement component. The discrimination unit subtracts the equivalent translational displacement component from the total rebound reading compensation, compares the calculated pure local elastic rebound with the preset value, and writes the final judgment result as a status label into the system's shared memory for direct use by the next round of correction decision module, thereby realizing closed-loop automatic interaction from data acquisition, physical quantity calculation to correction decision.

[0034] S5 includes: when the left side of the seam inspection gauge 6 overlaps smoothly and the right side is raised, it is determined that the outer surface of the workpiece on the right side is higher than the left side, and the radial contact head of the right positioning ring 3 is slightly retracted while keeping the axial push rod 5 in the same position unchanged; when the left side of the seam inspection gauge 6 is raised and the right side is smooth, the radial contact head of the left positioning ring 2 is slightly retracted; when the seam inspection gauge 6 shows repeated behavior during multiple checks in the same position, it is determined that there is local board edge wave, and the correction amplitude of that position is reduced, and the correction amount is shared by the two adjacent positions.

[0035] In S5, after the seam inspection ruler 6 is placed across the outer surfaces of both sides of the splice seam, if the left overlapping piece is in contact with the right overlapping piece while the right overlapping piece is away from the outer surface, it can be determined that the outer surface of the right workpiece in that position is higher than that of the left workpiece. When correcting, the radial contact head corresponding to the right positioning ring 3 is slightly retracted to release the outward convexity of the right side, while keeping the axial push rod 5 in the same position unchanged so that the seam contact tendency is not destroyed. If the inspection ruler shows that the left side is raised while the right side is in contact, the radial contact head corresponding to the left positioning ring 2 is slightly retracted to avoid forcibly flattening the misaligned edge by increasing the pressure on the right side. If the leveling ruler shows repeated changes in elevation when the same location is checked multiple times, it indicates that there may be local wavy edges or discontinuous edge curvature in that area, making it unsuitable for single-point concentrated correction. In this case, the individual retraction amount in that location should be reduced, and the correction amount should be distributed to the two adjacent locations to make the local geometric transition smoother. This implementation method directly corresponds the determination of the misalignment direction with the direction of the correction force, and by handling local wavy edges through the distribution of the amount in adjacent locations, the misalignment transfer caused by single-point overpressure can be reduced.

[0036] S6 includes: after spot welding at the top, if the pressure on the upper contact rod 4 increases and the pressure change of the lower contact rod 4 is less than or equal to the threshold, it is determined that the heat shrinkage pulls the seam edge together in the upward direction, the upper radial contact head is retracted, and the holding band corresponding to the lower radial contact head remains unchanged; after spot welding at the lower left, if the seam inspection gauge 6 shows an enhanced trend of right high and left low, the corresponding radial contact head on the right is pushed in with additional amount; The method also includes S7, which performs mutation identification and sequence protection. If the reading of any upper or side radial contact head suddenly increases and the reading of the opposite radial contact head does not change synchronously, and the contact rod 4 jumps under pressure, it is determined that the workpiece to be spliced ​​has not been completely settled. All axial push rods 5 are controlled to stop advancing, the upper radial contact head retracts to the contact start zone, and the lower radial contact head remains supported. After the reading returns to a stable state, it enters the holding zone again.

[0037] S6 is used for compliance control during spot welding; after the upper spot welding is completed, if the pressure of the upper contact rod 4 is increased while the pressure change of the lower contact rod 4 is less than the set threshold, it indicates that the welding heat shrinkage is mainly in the upper part, causing the seam edge to be further pulled together. At this time, the upper radial contact head is controlled to retract by a predetermined clearance level, while the lower radial contact head maintains the original holding level, so that the upper heat shrinkage is completed under controlled release conditions without damaging the lower support posture. After the spot welding at the lower left is completed, if the inspection gauge 6 shows an increasing trend of right-high and left-low, it indicates that the heat input has caused the workpiece on the right to bulge outward in that position. A small amount of push is added to the corresponding radial contact head on the right to counteract the heat traction in that direction. The same direction determination logic can be used to process the spot welding at the lower right. S7 is used to identify abnormal posture fluctuations. If the reading of any upper or side radial contact head suddenly increases within a short system cycle, while the reading of the opposite radial contact head does not change synchronously, and the contact rod 4 exhibits irregular jumping under pressure, it indicates that the workpiece may not be stably supported, there may be local snagging or incomplete external unloading. At this time, control all axial push rods 5 to stop advancing, the upper radial contact head retracts to the contact starting zone, and the lower radial contact head continues to support the workpiece; after the readings in all directions return to stability, the upper radial contact head is pushed back to the holding zone. This implementation combines spot welding heat drift adjustment and abnormal change protection in the same process, which can make targeted concessions or compensations along the main direction of heat shrinkage, and can also exit high-risk propulsion actions in time when abnormal forces occur. However, the heat shrinkage deformation generated by spot welding is usually at the sub-millimeter level. The static friction of the contact rod 4 in the guide bushing 31 can easily block this tiny deformation, resulting in the pressure depth not changing in a real way. As a result, the above-mentioned heat drift compensation logic fails due to the low signal-to-noise ratio. To overcome the conflict between mechanical lag and algorithm accuracy, this embodiment provides a linear ball bearing structure on the inner wall of the guide bushing 31 of the contact rod 4, replacing sliding contact with pure rolling contact, reducing the static friction of the system to a preset proportional threshold below the elastic force of the compression spring 32; at the same time, during the execution of S6, the control unit applies continuous low-frequency micro-amplitude excitation to the positioning ring frame, and micro high-frequency vibrators are rigidly fixed on the bodies of the left positioning ring frame 2 and the right positioning ring frame 3, which are driven by the control unit to generate vibration; using this micro-vibration as a chatter signal, the contact rod 4 and the guide bushing 31 are always in a state of dynamic friction; Therefore, even the smallest thermal shrinkage pulling force can be directly converted into the displacement of the contact rod 4 without being hindered by static friction, ensuring the authenticity and sensitivity of the data on the pressure change of the contact rod 4, and providing a reliable physical signal basis for the determination of the dominant branch of thermal shrinkage. The set threshold, the predetermined clearance level, and the short system cycle each play a different role in the process judgment. The set threshold is used to distinguish between normal minor fluctuations after spot welding and thermal shrinkage changes that are sufficient to trigger compensation actions. Its input is the difference in pressure depth of the same contact rod 4 before and after spot welding and the comparative change of the lower contact rod 4. When the pressure on the upper part increases significantly while the change on the lower part is still within the threshold, it is determined that the thermal shrinkage is mainly concentrated in the upper part. The predetermined clearance level is used to limit the range of motion of a single retraction or insertion. Its physical meaning is to release or compensate for local thermal deformation with a minimum controllable correction unit that does not disrupt the existing overall alignment relationship. The determination basis is preferably the single-step advancement resolution of the device, the width of the holding band, and the allowable single misalignment correction amount. It is usually taken as no more than a part of the width of the holding band, so that the radial contact head is still in a controllable contact range that can be quickly recovered after retraction. The short system cycle is used to identify whether the sudden change is persistent. Its input is the radial contact head reading and the pressure reading of the opposite contact rod 4 at several adjacent sampling times. Only when the abnormal increase and jumping occur continuously within the short system cycle, and the opposite reading does not show a corresponding linkage, is it determined to be an unstable landing or a local collision, rather than a single welding disturbance. The specific processing procedure is as follows: First, record the reference readings of the contact rod 4 and the radial contact head at each position before spot welding; after spot welding, read the pressure changes and the flat gauge fit status corresponding to the upper, lower left, and lower right positions in chronological order; if the heat shrinkage criterion is met, perform a single retraction or replenishment according to the predetermined clearance level, and retest again; if the heat shrinkage criterion is not met but an abnormal change occurs within a short period, immediately enter the sequential protection process of S7; in this way, the adjustment action after spot welding does not directly rely on the operator's experience, but is completed by the continuous logic of judging the source of the reading change - limiting the action amplitude - abnormal protection reset; S6 and S7 can be considered as two discriminant branches in the same compliance control logic. S6 corresponds to the normal compensation branch dominated by heat shrinkage, and S7 corresponds to the protection branch dominated by support instability or collision. The input of this compliance control logic is not a single reading, but consists of three sources: first, the pressure change of the same-position contact rod 4 before and after spot welding, which reflects the degree to which the seam edge is pulled together; second, the fit of the seam inspection ruler 6 in the corresponding position, which reflects whether the height relationship of the outer surface has shifted; and third, the linkage between the opposing radial contact head and adjacent sampling times, which is used to determine whether the change is overall thermal drift or local abnormal force. The judgment order is as follows: first, check whether the pressure change has a stable direction; then, check whether the leveling ruler shows a height change in the same direction; then, check whether there is a reasonable linkage between the readings in the opposite direction. If the first two are true and the change direction is consistent, it is preferentially classified into the heat shrinkage compensation branch. If the pressure change has no stable direction, the reading increases suddenly and there is no linkage in the opposite direction, it is classified into the sequence protection branch. The physical relationship represented by this logic is: spot welding thermal shrinkage usually manifests as a relatively continuous pulling or traction effect near the weld point, which will cause a directional correspondence between changes in pressure, changes in misalignment direction, and changes in local support force; while snagging, instability, or incomplete external unloading are more likely to manifest as sudden, abrupt, and discontinuous signals lacking counter-coordination. Because the two types of phenomena differ in signal source, duration, and linkage, the same reading system can be used for both thermal drift compensation and abnormal protection, without misjudging short-term impacts as normal welding shrinkage. To ensure the accurate execution of the above-mentioned compliant control logic in the industrial field, this embodiment clarifies the on-site calibration steps for setting thresholds and short system cycles: During the equipment deployment phase, the workpiece to be welded is selected to perform a standard spot welding process test, and the three-dimensional thermal deformation data of the area around the weld point and the pressure depth change sequence of each contact rod 4 are synchronously collected using a laser tracker or a high-precision displacement sensor. By comparing the actual thermal deformation gradient with the reading of the contact rod 4, the typical range of the pressure change of the contact rod 4 caused by thermal shrinkage under specific welding process parameters is calibrated. The lower limit of this typical range is used as the set threshold, so as to strictly distinguish it from the small fluctuations caused by environmental thermal fluctuations or machine tool vibration. For the calibration of the short system cycle, a non-destructive impact is applied to the workpiece under no-load conditions to reproduce local snagging or instability. The decay time window of the impact signal in the sensor network of the contact rod 4 and the radial contact head is recorded. 1.5 to 2 times the decay time window is taken as the short system cycle. The above calibration process physically binds the key parameters in the control logic to the actual welding thermodynamic behavior and specific mechanical shock response characteristics, overcoming the shortcomings of setting parameters based solely on experience, which leads to an opaque internal mechanism. This provides a quantitative basis for reproducible deployment in industrial settings. To ensure the real-time execution of the above compliant control and anomaly protection logic, this embodiment further clarifies the data flow and interaction protocols between system modules. The system adopts a control architecture consisting of an industrial computer, a multi-axis motion controller, and a high-frequency data acquisition card. During spot welding, the data acquisition card synchronously acquires the displacement sensor signals of each pair of contact rods 4 and the contact status signals of the seam inspection ruler 6 at a fixed sampling frequency, and packages them into data frames with timestamps and sends them to the industrial computer. The thermal drift judgment module in the industrial control computer analyzes the data frame in real time and extracts the amount of pressure change. If the thermal shrinkage criterion is met, it sends a position offset command of the predetermined clearance level to the multi-axis motion controller. The motion controller then converts the command into a pulse signal to drive the electric push rod 214 to move. Meanwhile, the anomaly monitoring module processes data frames in parallel. Once it detects that the reading jump amplitude exceeds the safety envelope within the set short system cycle, and there is no corresponding fluctuation characteristic in the opposite reading data stream, it immediately triggers a hardware interrupt, forcing the motion controller to output stop and rollback commands. Through the above-mentioned clear data channels and interrupt mechanisms, it is ensured that the judgment of the software algorithm can be seamlessly and with low latency converted into physical protection actions.

[0038] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A welding positioning device for assembling storage tanks, characterized in that, include: Base (1), left positioning ring frame (2), right positioning ring frame (3), contact rod (4), axial push rod (5), gap inspection ruler (6), and control unit; The control unit is connected to the radial contact head, the axial push rod and the gap inspection ruler respectively; the base (1) is a rectangular welded bed; The left positioning ring frame (2) and the right positioning ring frame (3) are both vertically fixed above the base (1), parallel to each other and with their center lines coplanar. The left positioning ring frame (2) is fixed to the left side of the base (1), and the right positioning ring frame (3) can be adjusted and locked along the length of the base (1). Radial contact head (21), radial contact head (22), radial contact head (23), and radial contact head (24) are respectively arranged above, to the left, to the right, and below the inner circumference of the left positioning ring frame (2); The inner circumference of the right positioning ring frame (3) is provided with radial contact head (25), radial contact head (26), radial contact head (27), and radial contact head (28); The contact rod (4) is arranged on the right side of the left positioning ring frame (2), located at the top, lower left and lower right and spaced equally apart, with its front end facing the splicing seam of the workpiece to be spliced; The axial push rod (5) is arranged on the left side of the right positioning ring frame (3), corresponding to the contact rod (4) in each direction, and in contact with the end face of the workpiece to be spliced. The seam inspection ruler (6) is placed across both sides of the seam on the outer surface of the workpiece to be spliced.

2. The welding positioning device for tank assembly according to claim 1, characterized in that, The radial contact head includes a guide seat (211), a slider (213), an electric push rod (214), a disc spring assembly (215), a reading sleeve (216), and a contact shoe (217); The guide seat (211) adopts a dovetail groove structure (212) and is fixed on the inner ring plate of the corresponding ring frame. The slider (213) and the dovetail groove structure (212) are in clearance fit. The cylinder end of the electric push rod (214) is connected to the rear side of the guide seat (211), the rod end of the electric push rod (214) is connected to the pressure plate, the front of the pressure plate presses against the disc spring assembly (215), the front end of the disc spring assembly (215) presses against the reading sleeve (216), and the reading sleeve (216) is fixedly connected to the rear end of the contact shoe (217) to form a limited force contact chain that transmits force in the radial direction. The outer circle of the reading sleeve (216) is engraved with circumferential lines, and the guide seat (211) has a zero-position scale fixed on its outer side.

3. The welding positioning device for tank assembly according to claim 2, characterized in that, The radial contact head (24) located below the left positioning ring frame (2) and the radial contact head (28) located below the right positioning ring frame (3) have contact shoes (217) with roller-type structure (218); the outer circle of the roller is covered with a polyurethane layer (219), and the roller is supported between the fork frame (220) by bearings (221). The rear end of the fork frame (220) is fixed to the reading sleeve (216) by a spherical washer (222); The radial contact heads located above, to the left and right of the left positioning ring frame (2) and the right positioning ring frame (3) have an arc-shaped pressure shoe structure (223) for their contact shoes (217); the front surface of the pressure shoe is covered with a polytetrafluoroethylene composite wear-resistant layer (224), and the pressure shoe is connected to the reading sleeve (216) by a ball head screw (225).

4. The welding positioning device for tank assembly according to claim 1, characterized in that, The left positioning ring frame (2) has a guide hole on its right side and a guide bushing (31) is installed thereon. The contact rod (4) passes through the guide bushing (31) on the left positioning ring frame (2). A compression spring (32) is sleeved on the rear end of the contact rod (4). A limiting nut (33) is provided behind the compression spring (32). The front end of the contact rod (4) is a rounded contact (34). The outer circle of the contact rod (4) is equipped with a etched sleeve (35). The axial push rod (5) adopts a direct push electric cylinder (36), and the rod end of the axial push rod (5) is connected to a replaceable nylon pressure head (37); the gap inspection ruler (6) includes a left overlapping piece (38), a middle bridge plate (39), and a right overlapping piece (40); the middle bridge plate (39) adopts an elastic steel sheet (41), the left overlapping piece (38) and the right overlapping piece (40) are respectively fixed at both ends of the middle bridge plate (39), and the lower surfaces of the left overlapping piece (38) and the right overlapping piece (40) are flush with the same plane.

5. A welding positioning method for assembling a storage tank, based on the apparatus described in any one of claims 1 to 4, characterized in that, include: S1, perform initial zeroing and place the workpiece to be spliced ​​inside the left positioning ring frame (2) and the right positioning ring frame (3), keep the radial contact head and the axial push rod (5) retracted, so that the lower radial contact head supports the workpiece. The contact start zone is the position range in which the radial contact head and the workpiece form a stable contact but have not yet established a significant additional clamping force. The holding zone is the position range in which the radial contact head establishes a controlled support force on the workpiece and the reading increment changes continuously and stably. Push the upper, left and right radial contact heads to the contact start zone and record the readings. S2, perform single-piece roundness judgment, push the radial contact head to the middle of the holding band for the workpiece in the left positioning ring frame (2) and right positioning ring frame (3), compare the changes in readings in each position in the same ring frame and reduce the pushing depth of the position with the largest clearance; S3, perform docking and error classification, drive the right workpiece to move closer to the left workpiece and determine the source of error based on the pressure depth of the docking contact rod (4); S4, perform release check, keep the other azimuths stable, retract the radial contact head of the corrected azimuth to the contact start zone and then advance it again and compare the readings; S5, perform misalignment judgment and local correction, place the cross-seam inspection flat ruler (6) and control the radial contact head of the corresponding position to slightly retreat according to the overlap state; S6, execute spot welding conformity control, and control the radial contact head to retract or advance according to the pressure change of the contact rod (4) after spot welding and the status of the inspection gauge (6).

6. The method according to claim 5, characterized in that, S2 includes: comparing the changes in readings in the left and right directions, the changes in readings in the top and bottom directions, and the total changes in the four directions within the same ring frame; when the changes in readings in the left and right directions are close and the changes in the top readings are greater than the changes in the bottom readings, it is determined that the workpiece to be spliced ​​has a tendency to flatten vertically. When the readings on the left and right sides are asymmetrical, it is determined that there is lateral eccentricity in the workpiece to be spliced; when the total change in each direction increases and the difference in direction is not prominent, it is determined that the clamping induces a reduction in diameter; reduce the radial push depth according to the direction with the largest clearance, and balance its opposite and adjacent directions.

7. The method according to claim 5, characterized in that, The S3 includes: the axial push rod (5) pushes the right workpiece in phase until the contact rod (4) enters the pressure state and then stops the uniform push; when the pressure on the upper contact rod (4) is greater than that on the two lower contact rods (4), it is determined that the right workpiece has pitch tilt, the upper axial push is reduced, and the radial contact head above the right positioning ring frame (3) is slightly retracted; when the pressure difference between the lower left and lower right contact rods (4) is greater than the set threshold, it is determined that there is sway tilt, and the push balance of the left and right radial contact heads is corrected first.

8. The method according to claim 5, characterized in that, The S4 includes: the preset value is a limit threshold determined by the device reading resolution, workpiece wall thickness and allowable springback amount; when the reading compensation after the next advance is less than or equal to the preset value, it is determined that the previous correction eliminated the true geometric deviation; when the reading compensation after the next advance is greater than the preset value and the readings in adjacent directions change synchronously, it is determined that the previous correction included clamping-induced deformation, and in the next round of correction, the advance amount in the same direction is reduced and the opposing balance amount is increased.

9. The method according to claim 5, characterized in that, The S5 includes: when the left side of the seam inspection ruler (6) overlaps smoothly and the right side is raised, it is determined that the outer surface of the workpiece on the right side is higher than the left side, and the right positioning ring frame (3) is controlled to slightly retract the corresponding radial contact head and keep the axial push rod (5) in the same position unchanged. When the left side of the seam inspection ruler (6) is raised and the right side is smooth, the left positioning ring frame (2) is slightly retracted to the corresponding radial contact head; when the seam inspection ruler (6) shows repeated behavior when checked multiple times in the same position, it is determined that there is local board edge wave, and the correction range of that position is reduced, and the correction amount is shared by the two adjacent positions.

10. The method according to claim 5, characterized in that, S6 includes: after spot welding at the top, if the pressure of the upper contact rod (4) is increased and the pressure change of the lower contact rod (4) is less than or equal to the threshold, it is determined that the heat shrinkage pulls the seam edge together in the upward direction, the upper radial contact head is retracted, and the holding band corresponding to the lower radial contact head remains unchanged; after spot welding at the lower left, if the seam inspection ruler (6) shows an enhanced trend of right high and left low, the corresponding radial contact head on the right side is pushed in with additional amount; The method also includes S7, which performs mutation identification and sequence protection. If the reading of any upper or side radial contact head suddenly increases and the reading of the opposite radial contact head does not change synchronously, and the contact rod (4) is pressed and jumps, it is determined that the workpiece to be spliced ​​has not been completely settled. All axial push rods (5) are controlled to stop moving forward, the upper radial contact head retracts to the contact start zone, and the lower radial contact head remains supported. After the reading returns to a stable state, it enters the holding zone again.

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