A welding anti-deformation control clamp for building steel structure

Abstract

The present application relates to welding fixture technical field, specifically to a kind of building steel structure welding anti-deformation control fixture, including bottom plate, support mechanism and lateral clamping mechanism, support mechanism is installed on bottom plate, for the bottom support and auxiliary limiting to component, lateral clamping mechanism includes cooling module with cooling medium flow channel in inside, cooling module is arranged between lateral clamping mechanism execution end and component surface, and cooling module and execution end are elastically floating connection, and the connection is realized by heat-sensitive self-compensation module being arranged between the both;Heat-sensitive self-compensation module is made of shape memory alloy elastic element, and its phase transition temperature is set in the working temperature range of component welding heat-affected zone.The present application couples active cooling and clamping force as heat-power closed loop, reduces welding thermal expansion total amount from source, effectively alleviates the inherent contradiction between traditional fixture passive constraint and thermal expansion release, and anti-deformation effect is remarkable.

Description

Technical Field

[0001] This invention relates to the field of welding fixture technology, and specifically to a welding deformation control fixture for building steel structures. Background Technology

[0002] In on-site welding of steel structures, butt welding of components such as steel pipes and H-beams is a common process. Due to the local high temperature during welding, the metal near the weld expands thermally and is constrained by the cold metal further away, resulting in compressive plastic deformation in the near-weld zone. During cooling, the metal contracts but is also constrained, generating residual tensile stress, which ultimately leads to welding deformations such as bending and twisting of the component.

[0003] To control deformation, existing clamps mostly employ mechanical force for forced constraint. For example, Chinese patent CN224043009U discloses a pneumatic welding clamp for preventing deformation of thin-walled pipe fittings. This clamp uses pneumatic side clamps to tighten the pipe fitting from both sides, and works with a bottom bracket to achieve multi-point support, suppressing deformation by dispersing stress. However, this type of solution is essentially a passive constraint, which has an inherent contradiction: if the constraint is too strong, thermal expansion has nowhere to be released, and residual stress increases; if the constraint is too loose, it is difficult to effectively control macroscopic deformation.

[0004] Therefore, those skilled in the art have provided a welding deformation control fixture for building steel structures to solve the problems mentioned in the background art. Summary of the Invention

[0005] To solve the above-mentioned technical problems, the present invention provides a welding deformation control fixture for building steel structures, comprising: The base plate serves as the mounting base and is used to support the various functional modules; A lateral clamping mechanism, mounted on the base plate, is used to apply clamping force from both radial sides of the steel structure component to be welded; The lateral clamping mechanism includes a cooling module, which has a cooling medium flow channel inside. The cooling module is located between the execution end of the lateral clamping mechanism and the surface of the component, and the side of the cooling module facing the component is the cooling contact surface. The cooling module and the actuator of the lateral clamping mechanism are connected by an elastic floating connection, which is achieved by a thermal self-compensation module disposed between the two. The thermal self-compensation module is composed of shape memory alloy elastic elements, with its two ends abutting against the execution end of the lateral clamping mechanism and the back of the cooling module, respectively. The phase transformation temperature of the shape memory alloy elastic element is set within the working temperature range of the component welding heat-affected zone. When the temperature reaches the phase transition point, the shape memory alloy elastic element expands and displaces, pressing the cooling module toward the surface of the component to reduce contact thermal resistance and enhance thermal conductivity, forming a closed-loop linkage of clamping force and cooling efficiency with positive feedback as temperature rises.

[0006] Preferably, it also includes a support mechanism, which is installed at the middle position of the upper surface of the base plate, for bottom support and auxiliary limiting of the component to be welded, and has the function of adjusting the spacing along the axial direction of the component; The supporting mechanism includes support columns, a dual-head motor, a lead screw, and a V-shaped clamp. There are two support columns, which are spaced apart along the axial direction of the component. Their bottoms slide in a groove on the upper surface of the base plate. The V-shaped clamp is installed on the top of the support column to receive and limit the component. The dual-head motor drives the lead screw to move the two support columns closer or further apart synchronously to adjust the support spacing.

[0007] Preferably, the shape memory alloy elastic element is a spring sheet structure or a shape memory alloy spring, wherein the shape memory alloy spring is a helical compression spring or a disc spring assembly.

[0008] Preferably, the thermal self-compensation module includes multiple shape memory alloy elastic elements, and the two ends of each shape memory alloy elastic element are respectively abutted against the execution end of the lateral clamping mechanism and the back of the cooling module through pads.

[0009] Preferably, the phase transformation temperature of the shape memory alloy elastic element is set between 80℃ and 120℃, its material is Ni-Ti alloy, and the austenitic phase transformation end temperature Af is set to 90℃.

[0010] Preferably, the lateral clamping mechanism includes a driving component, which includes a hydraulic rod. A push plate is fixedly connected to the piston end of the hydraulic rod. The push plate serves as the execution end of the lateral clamping mechanism and has a through hole. The cooling module includes a guide rod, one end of which is fixedly connected to the cooling module, and the other end of which passes through a through hole in the push plate and forms a sliding fit.

[0011] Preferably, the cooling module includes a clamping seat, and the side of the clamping seat facing the component is machined with an arc-shaped surface, the radius of curvature of the arc-shaped surface matching the outer diameter of the component to be welded; The cooling medium flow channel is arranged in a serpentine pattern and located inside the clamping seat. It is connected to an inlet pipe at the inlet and an outlet pipe at the outlet. The clamping seat is made of copper.

[0012] Preferably, the lateral clamping mechanism further includes an adjustment frame, which includes a frame body and an electric push rod. The frame body serves as a common mounting carrier for the drive component, cooling module, and thermal self-compensation module. Its bottom is slidably engaged with a groove opened on the upper surface of the base plate. The electric push rod is fixed to the base plate, and its telescopic end is connected to the frame body for driving the frame body to move axially along the component.

[0013] Preferably, it also includes a self-alarm module, which is disposed between the cooling module and the execution end of the lateral clamping mechanism, and includes a pressure sensing component and a shape memory alloy drive component; The shape memory alloy drive and the shape memory alloy elastic element are made of the same material and have the same phase transition temperature. One end of the drive abuts against the back of the cooling module, and the other end acts on the detection surface of the pressure sensing component. When the cooling module overheats abnormally, the shape memory alloy drive component generates an axial expansion displacement that exceeds the normal operating range, applying a contact pressure exceeding the preset standard value to the pressure sensing component and triggering an alarm.

[0014] Preferably, the pressure sensing component is fixedly installed on the push plate, and a pressure sensor is integrated inside it. An audible and visual alarm is also installed on it. The audible and visual alarm is electrically connected to the pressure sensor. When the pressure value exceeds the preset standard value, the audible and visual alarm is triggered.

[0015] The technical effects and advantages of this invention are as follows: (1) Through the synergistic effect of active cooling and thermosensitive self-compensation, the present invention automatically realizes a positive feedback closed loop in the welding process, which is characterized by the greater the temperature rise, the tighter the cooling contact, and the higher the thermal conductivity. This reduces the total thermal expansion of the component from the source, so that the mechanical constraint does not need to be too strong to effectively suppress macroscopic deformation. At the same time, when the temperature drops after welding, the additional clamping force is automatically released, which avoids over-constraining the shrinking weld and is conducive to the gradual release of residual stress. Thus, a better balance is achieved between deformation control and stress release. (2) The thermosensitive self-compensation module of the present invention is composed of shape memory alloy elastic elements, which is driven entirely by welding residual heat. The pure mechanical closed-loop linkage mode has a simple structure and good environmental adaptability, and is especially suitable for complex working conditions at construction sites. (3) The efficient heat conduction of the cooling module of the present invention reduces the peak temperature and temperature gradient of the heat-affected zone, reduces the accumulation of compressive plastic deformation in the near weld zone, and reduces the peak value of residual tensile stress after welding, which is beneficial to improving the load-bearing capacity and fatigue life of the welded joint; at the same time, accelerating the cooling rate of the high-temperature section can inhibit the excessive growth of austenite grains, promote the formation of fine grain structure, and improve the toughness and strength of the weld. (4) The phase transformation temperature of the shape memory alloy elastic element of the present invention can be selected according to the wall thickness of the component and the heat input of the welding process. For thin-walled pipes or low-current welding, a lower phase transformation temperature can be selected to trigger cooling enhancement earlier; for thick-walled components or high heat input welding, a higher phase transformation temperature can be selected to intervene under higher heat load, avoiding unnecessary premature action, and realizing wide adaptability to components of different specifications and welding processes. (5) The self-alarm module and the thermal self-compensation module of the present invention share the same heat source and the phase change point is synchronized. When the cooling system fails and the cooling module overheats abnormally, the alarm can be automatically triggered to remind the operator to intervene in time, prevent deformation out of control or damage to the surface of the component caused by cooling failure, and provide safety guarantee for welding operations. Attached Figure Description

[0016] Figure 1 This is a structural schematic diagram of a welding deformation control fixture for building steel structures provided in an embodiment of this application; Figure 2 This is a front view of a welding deformation control fixture for building steel structures provided in an embodiment of this application; Figure 3 This is a top view of a welding deformation control fixture for building steel structures provided in an embodiment of this application; Figure 4 This is an exploded view of a welding deformation control fixture for building steel structures provided in an embodiment of this application; Figure 5 This is an exploded view of the support mechanism in a welding anti-deformation control fixture for building steel structures provided in an embodiment of this application; Figure 6 This is a schematic diagram of the lateral clamping mechanism in a welding anti-deformation control fixture for building steel structures provided in an embodiment of this application; Figure 7 This is a partial exploded view of the lateral clamping mechanism in a welding anti-deformation control fixture for building steel structures provided in this application embodiment; Figure 8 This is a partial structural schematic diagram of the lateral clamping mechanism in a welding anti-deformation control fixture for building steel structures provided in an embodiment of this application; Figure 9 This application provides an embodiment of a welding deformation control fixture for building steel structures. Figure 8 Top view; Figure 10 This application provides an embodiment of a welding deformation control fixture for building steel structures. Figure 8 Decomposition diagram; Figure 11 This is a schematic diagram of the self-alarm module in a welding anti-deformation control fixture for building steel structures provided in this application embodiment.

[0017] In the picture: 1. Base plate; 2. Slide groove; 3. Supporting mechanism; 4. Lateral clamping mechanism; 31. Support column; 32. Dual-head motor; 33. Lead screw; 34. Bearing plate; 35. Threaded sleeve; 36. V-clamp; 41. Adjustment frame; 42. Drive unit; 43. Cooling module; 44. Thermosensitive self-compensation module; 45. Self-alarm module; 411. Frame; 412. Electric actuator; 413. Mounting bracket; 421. Hydraulic rod; 422. Push plate; 423. Through hole; 431. Clamping seat; 432. Arc-shaped surface; 433. Inlet pipe; 434. Outlet pipe; 435. Guide rod; 441. Shape memory alloy elastic element; 442. Pad; 451. Pressure sensing component; 452. Shape memory alloy drive component; 453. Audible and visual alarm. Detailed Implementation

[0018] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. The embodiments of the present invention are given for illustrative and descriptive purposes only, and are not intended to be exhaustive or to limit the invention to the forms disclosed. Many modifications and variations will be apparent to those skilled in the art. The embodiments were chosen and described to better illustrate the principles and practical application of the invention, and to enable those skilled in the art to understand the invention and design various embodiments with various modifications suitable for a particular purpose. Example

[0019] Please see Figures 1 to 11 This embodiment provides a welding deformation prevention control fixture for building steel structures. The overall structure of the control fixture is as follows: Figure 1 , Figure 2 and Figure 3 As shown, it mainly includes a base plate 1, a support mechanism 3, and a lateral clamping mechanism 4. The base plate 1 serves as the mounting base for the entire control fixture. It can be placed directly on the ground according to the construction site conditions, or fixed to the work platform and other load-bearing structures by bolts, providing a reference plane for the subsequent installation of various functional modules. The support mechanism 3 is installed at the middle of the upper surface of the base plate 1. Its function is to provide bottom support and auxiliary limit for the steel structural components placed on it—taking steel pipe as an example in this embodiment—to improve the stability of the components during the welding process. The support mechanism 3 has the function of adjusting the spacing along the axial direction of the steel pipe. When the length of the steel pipe to be welded is long, the axial spacing of the support part inside the support mechanism 3 can be increased to make it more evenly supported within the component range, effectively suppressing the deflection caused by its own weight, thereby better adapting to the welding support requirements of long-sized components. Two lateral clamping mechanisms 4 are provided, which are installed on the left and right sides of the upper end of the base plate 1 and located on both sides of the supporting mechanism 3, and are used to apply clamping constraints from the radial direction of the steel pipe. In this embodiment, the specific structure of the supporting mechanism 3 is as follows: Figure 4 , Figure 5 As shown, it mainly includes a support column 31, a double-headed motor 32, a lead screw 33, and a V-clamp 36; Two support columns 31 are provided, which are distributed at intervals along the axial direction of the steel pipe above the base plate 1. The bottom of each support column 31 is placed in the sliding groove 2 opened on the upper end surface of the base plate 1, forming a sliding fit with the sliding groove 2. The sliding groove 2 extends along the axial direction of the steel pipe and plays a guiding and limiting role in the movement of the support column 31, ensuring that it maintains straight line accuracy during left and right displacement and does not wobble. Each support column 31 has a threaded sleeve 35 embedded inside. Correspondingly, the dual-head motor 32 is fixedly installed on the upper end face of the base plate 1 and is located in the middle position between the two support columns 31. The output shafts at both ends of the dual-head motor 32 are each connected to a lead screw 33. The threads of the two lead screws 33 are opposite. The lead screw 33 passes through the threaded sleeve 35 in the corresponding side support column 31 and forms a threaded transmission engagement with the threaded sleeve 35. The end of the lead screw 33 away from the dual-head motor 32 is rotatably supported by a bearing plate 34. The bearing plate 34 is fixedly installed on the upper end face of the base plate 1 to bear the axial load of the lead screw 33 and ensure its rotational accuracy. When the dual-head motor 32 is started, the output shafts at both ends rotate synchronously, driving the lead screws 33 on both sides to rotate. Since the threads of the lead screws 33 on both sides rotate in opposite directions, the rotational motion of the lead screws 33 is converted into the linear movement of the support column 31 in the slide groove 2 through the threaded sleeve 35, driving the two support columns 31 to move closer or further away from each other synchronously, thereby realizing the adjustment of the axial distance between the two support columns 31. This distance can be flexibly adjusted according to the length of different steel pipes, so that the fixture can be adapted to components of various specifications and lengths, thereby improving the adaptability and practicality of the fixture. A V-shaped clamp 36 is installed on the top of each support column 31. The upper end of the V-shaped clamp 36 is open to receive the steel pipe and to achieve radial limit and vertical support. The inner wall of the V-shaped clamp 36 is provided with an anti-slip pad, which can be made of high temperature resistant silicone rubber or polytetrafluoroethylene composite material. Its function is to increase the friction coefficient between the clamp and the outer wall of the steel pipe, prevent the steel pipe from axial movement or circumferential rotation during the welding process, and avoid scratches or indentations caused by direct hard contact between the metal clamp and the surface of the steel pipe. To further enhance the versatility of the support, the V-clamp 36 can be detachably fixed to the top of the support column 31 by bolts. When the diameter of the steel pipe to be welded changes, the V-clamp 36 with different opening angles or different slot sizes can be replaced to adapt to steel pipes of different diameters without replacing the entire support mechanism 3. As an alternative, in another embodiment, the dual-head motor 32 can be replaced by a manual turntable with a worm gear reduction mechanism. The screw 33 is driven to rotate by manually rotating the handwheel, so as to achieve spacing adjustment under conditions without power supply, in order to adapt to construction sites in the field or where power is inconvenient. In this embodiment, the lateral clamping mechanism 4 is a key improved structure of the present invention, and its specific construction is as follows: Figure 6As shown, it mainly includes an adjustment frame 41, a drive component 42, a cooling module 43, a thermal self-compensation module 44, and a self-alarm module 45; The adjusting frame 41 serves as the support base for the lateral clamping mechanism 4 and is installed on the upper surface of the base plate 1. The adjusting frame 41 can be adjusted in position along the length direction of the base plate 1 (i.e., the axial direction of the steel pipe). Through the axial adjustment function, the lateral clamping mechanism 4 can flexibly adjust the clamping position according to the length of different steel pipes to ensure that the clamping force always acts on the area close to the end face of the steel pipe, thereby achieving a stable and reliable clamping effect on components of various specifications. On the adjusting frame 41, a set of driving components 42 are set on each of the radial sides of the steel pipe. The driving components 42 provide the lateral clamping mechanism 4 with clamping power along the radial direction of the steel pipe. The cooling module 43 is set between the execution end of the driving component 42 and the outer wall surface of the steel pipe. Its side facing the steel pipe is the cooling contact surface. Cooling medium channels are machined inside. During the welding process, circulating coolant is introduced into the cooling medium channels. The cooling module 43 absorbs welding heat through close contact with the surface of the steel pipe and actively cools the heat-affected zone near the weld. The cooling module 43 and the actuator 42 are connected by an elastic floating connection. This elastic floating connection is achieved by a thermal self-compensation module 44 disposed between the two. The thermal self-compensation module 44 is composed of a shape memory alloy elastic element 441, with its two ends abutting against the actuator 42 and the back of the cooling module 43 respectively—that is, the side of the cooling module 43 away from the steel pipe. The phase transformation temperature of the shape memory alloy elastic element 441 is preset within the working temperature range of the heat-affected zone of the steel pipe welding. When the welding heat is conducted through the outer wall of the steel pipe to the cooling module 43, and then from the back of the cooling module 43 to the shape memory alloy elastic element 441 and its temperature reaches the phase transformation point, the shape memory alloy elastic element 441 undergoes a phase transformation from martensite to austenite, generating axial expansion displacement, which further presses the cooling module 43 toward the surface of the steel pipe. This additional pressing force reduces the contact thermal resistance between the cooling module 43 and the outer wall of the steel pipe, and enhances the thermal conductivity, thereby forming a positive feedback closed-loop linkage between the clamping force and the cooling efficiency that automatically increases with the temperature. It should be noted that the reason for the deformation of the steel pipe during welding is that the welding heat input causes non-uniform thermal expansion of the metal near the weld. However, the present invention continuously removes the welding heat through the efficient heat conduction of the cooling module 43, thereby reducing the peak temperature of the heat-affected zone of the steel pipe and the total amount of overall thermal expansion. This reduces the amount of expansion deformation of the component during welding, thereby weakening the driving force of deformation from the source, rather than passively constraining it by mechanical force after deformation has occurred, as is the case with traditional clamps. Furthermore, the residual stress in welding originates from the compressive plastic deformation caused by the constraint of thermal expansion. This invention reduces the temperature gradient in the heat-affected zone through active cooling, reduces the amount of expansion and the degree of constraint of the metal in the high-temperature zone, effectively reduces the accumulation of compressive plastic deformation in the near-weld zone, and thus reduces the peak value of residual tensile stress in the post-weld cooling stage, which is beneficial to improving the load-bearing capacity and fatigue life of the welded joint. Meanwhile, the efficient heat conduction of the cooling module accelerates the cooling rate of the weld and heat-affected zone in the high-temperature section, shortens the high-temperature dwell time, which helps to suppress the excessive growth of austenite grains, promotes the formation of fine grain structures such as acicular ferrite, improves the microstructure and mechanical properties of the welded joint, and enhances the toughness and strength of the weld. Based on this, the above solution reduces the total amount of thermal expansion and the burden of passive mechanical constraints by using positive feedback closed-loop linkage of thermo-mechanical forces. This allows the fixture to effectively suppress macroscopic deformation without relying on excessive rigid constraints, alleviating the contradiction between constraint stiffness and thermal expansion release in traditional fixtures, and achieving better anti-deformation effect during welding clamping. After welding, the temperature of the steel pipe gradually drops, and the temperature of the cooling module 43 body decreases accordingly. The shape memory alloy elastic element 441 returns to the low-temperature martensitic state, and the additional clamping force generated by it is automatically released, leaving only the basic clamping force provided by the drive component 42. This characteristic ensures that the weld will not be subjected to excessive constraints during the cooling and shrinkage stage, thus hindering the gradual release of its stress. This helps to reduce residual stress concentration and prevent the generation of secondary deformation after welding. In addition, a self-alarm module 45 is provided between the cooling module 43 and the actuator 42. The self-alarm module 45 is located in the middle area of ​​the thermal self-compensation module 44. Its triggering principle is also based on the conduction of heat from steel pipe welding. When the cooling module 43 is abnormally overheated due to reasons such as coolant interruption, pipeline blockage or circulation pump failure, the heat received by the self-alarm module 45 exceeds the normal operating threshold and can automatically trigger an alarm to issue a fault warning to the on-site operators, thereby improving the safety of welding operations. The specific structure of the adjustment frame 41 is as follows: Figure 7 As shown, it mainly includes a frame 411, an electric actuator 412, and a mounting bracket 413; The frame 411 serves as the common mounting carrier for the various functional modules in the lateral clamping mechanism 4—driving component 42, cooling module 43, thermal self-compensation module 44, and self-alarm module 45. Its bottom is placed in the sliding groove 2 opened on the upper surface of the base plate 1, forming a sliding fit with the sliding groove 2. The sliding groove 2 extends along the axial direction of the steel pipe, guiding and limiting the movement of the frame 411, ensuring that it maintains straight accuracy during displacement and does not wobble or jam. Electric actuator 412 is arranged on one side of the frame 411 along the axial direction of the steel pipe. It is fixedly connected to the upper end face of the base plate 1 through the mounting bracket 413. The telescopic end of the electric actuator 412 is fixedly connected to the corresponding side wall of the frame 411. When the electric actuator 412 receives a control signal, its actuator extends or retracts, driving the frame 411 to slide along the slide groove 2, thereby driving the entire lateral clamping mechanism 4 to move along the axial direction of the steel pipe. By controlling the stroke of the electric actuator 412, the clamping center of the lateral clamping mechanism 4 can be positioned near the welding end face of steel pipes of different lengths, ensuring that the cooling module 43 and the heat-sensitive self-compensation module 44 always act on the position close to the heat-affected zone of the weld, realizing adaptive position adjustment for steel pipes of different specifications. To further enhance the reliability and safety of position adjustment, the electric actuator 412 can be a worm gear type electric actuator with self-locking function. It can maintain its current position when the power is off, preventing the frame 411 from being accidentally displaced due to external interference. In addition, a manual locking screw can be installed between the frame 411 and the slide 2. After the electric actuator 412 adjusts the frame 411 to the target position, the operator can tighten the screw for auxiliary mechanical locking, forming a double insurance of electrical self-locking and mechanical locking. This is a standard setting, and the specific structure is not shown in the attached drawings. For details regarding the structure of the drive unit 42, cooling module 43, and thermal self-compensation module 44, please refer to [reference needed]. Figure 8 , Figure 9 and Figure 10 ; The driving component 42 includes a hydraulic rod 421. The cylinder of the hydraulic rod 421 is embedded in the inner wall of the frame 411. The piston end of the hydraulic rod 421 is fixedly connected to a push plate 422. A through hole 423 is opened on each of the left and right sides of the push plate 422. When the piston rod of the hydraulic rod 421 extends or retracts, it drives the push plate 422 to move toward or away from the steel pipe, thereby pushing the cooling module 43 to feed synchronously, realizing the clamping or releasing action of the lateral clamping mechanism on the steel pipe. The hydraulic rod 421 serves as the power source for lateral clamping. Its output force is transmitted to the cooling module 43 through the push plate 422 and finally acts on the outer wall of the steel pipe. The cooling module 43 includes a clamping seat 431. The clamping seat 431 has an arc-shaped surface 432 machined on the side facing the steel pipe. The radius of curvature of the arc-shaped surface 432 matches the outer diameter of the steel pipe to be welded, so that the two can achieve surface contact and fit together in the clamping state to maximize the heat conduction contact area. The clamping seat 431 has a serpentine cooling medium channel inside. The inlet and outlet of the channel are respectively opened on both sides of the clamping seat 431. The inlet is connected to the liquid inlet pipe 433, and the outlet is connected to the liquid outlet pipe 434. The liquid inlet pipe 433 and the liquid outlet pipe 434 are respectively connected to the external circulating cooling mechanism. The cooling medium (which can be cooling water) flows through the cooling medium channel inside the clamping seat 431 under the drive of the circulating cooling mechanism, continuously carrying away the welding heat conducted from the steel pipe wall to the clamping seat 431. The clamping seat 431 can be made of copper. The excellent thermal conductivity of copper reduces the thermal resistance in the heat conduction path, so that the welding heat is quickly transferred from the surface of the steel pipe to the cooling medium and carried away. The cooling module 43 also includes two guide rods 435, which are respectively disposed on the left and right sides of the clamping seat 431. One end of the guide rod 435 is fixedly connected to the side of the clamping seat 431, and the other end extends toward the push plate 422 and passes into the through hole 423 on the push plate 422, forming a sliding fit with the through hole 423. The end of the guide rod 435 is provided with a locking block with a radial dimension larger than the diameter of the through hole 423. The locking block is used to limit the maximum sliding stroke of the guide rod 435 and prevent the guide rod 435 from coming out of the through hole 423. A floating space is left between the back of the clamping seat 431 and the front end of the push plate 422. The thermal self-compensation module 44 is installed in this floating space. The thermal self-compensation module 44 is composed of multiple shape memory alloy elastic elements 441. The two ends of each shape memory alloy elastic element 441 are respectively connected to the front end of the push plate 422 and the back of the clamping seat 431 through the pads 442. The pads 442 increase the bearing area between the shape memory alloy elastic element 441 and the two side contact surfaces, making the thrust distribution more uniform, and improving the heat conduction efficiency from the clamping seat 431 to the shape memory alloy elastic element 441. When the welding heat is conducted through the outer wall of the steel pipe to the clamping seat 431, and then through the back of the clamping seat 431 to the shape memory alloy elastic element 441 via the pad 442, and when the temperature of the shape memory alloy elastic element 441 reaches the phase transformation point, the shape memory alloy elastic element 441 undergoes a phase transformation from martensite to austenite, generating axial expansion displacement, driving the clamping seat 431 to overcome the sliding friction between the guide rod 435 and the through hole 423, and further move and press along the axial direction of the through hole 423 towards the surface of the steel pipe, thereby forming a positive feedback closed loop linkage between the clamping force and the cooling efficiency that automatically increases with the temperature. When the welding ends and the temperature drops, the shape memory alloy elastic element 441 returns to the martensitic state, the additional pressing force is automatically released, and the clamping seat 431 maintains a basic floating and fitting state under the guidance of the guide rod 435. In this embodiment, the specific structure of the shape memory alloy elastic element 441 is as follows: Figure 10 As shown, it is a spring structure, but it should be understood that the specific form of the shape memory alloy elastic element 441 is not limited to this. It can also be set as a shape memory alloy spring, such as a helical compression spring or a disc spring assembly, as long as it can meet the functional requirements of generating axial displacement and outputting sufficient thrust at the phase change temperature point. The phase transformation temperature of the shape memory alloy elastic element 441 is set between 80℃ and 120℃. Its material can be a Ni-Ti alloy. Specifically, the austenitic phase transformation end temperature Af can be set to approximately 90℃. The technical basis for this temperature setting is as follows: First, the austenite termination temperature Af of Ni-Ti shape memory alloy is not a fixed value, but is precisely controlled by adjusting the Ni content and heat treatment process. The Af temperature range of commercial Ni-Ti shape memory alloy formulations covers -50℃ to +350℃, and the Af temperature of 90℃ is completely within the industrial selection range, without any obstacles in terms of material acquisition or cost. Secondly, the shape memory alloy elastic element 441 is located on the back of the cooling module 43. Heat needs to be conducted step by step through the outer wall of the steel pipe → the arc surface 432 → the body of the clamping seat 431 → the pad 442 → the shape memory alloy elastic element 441. During this process, the circulating cooling medium inside the clamping seat 431 continuously removes a large amount of heat, resulting in a gradient attenuation of the back temperature of the clamping seat 431 relative to the temperature of the outer wall of the steel pipe near the weld. Even if the temperature of the outer wall of the steel pipe near the weld reaches several hundred degrees, the steady-state working temperature of the back of the clamping seat 431 after forced heat conduction and cooling usually falls in the range of 70 to 120 degrees. 90 degrees is exactly in the middle of this range. Setting the phase change point within this range can ensure that the elastic element is activated when the welding heat input reaches a certain level, rather than being triggered prematurely. Furthermore, the phase transformation temperature can be flexibly adjusted according to the actual welding process conditions. 90°C is only an exemplary setting for the conditions of this embodiment. For thin-walled pipes or low-current welding processes, the cooling requirement is more urgent. A shape memory alloy elastic element 441 with a phase transformation temperature of 80 to 90°C can be selected to trigger cooling enhancement earlier. For thick-walled components or high heat input welding processes, a shape memory alloy elastic element 441 with a phase transformation temperature of 100 to 120°C can be selected so that additional clamping force is applied only under higher heat load, avoiding unnecessary early intervention. This flexibility of customization on demand enables the present invention to adapt to a variety of welding scenarios. The self-alarm module 45 serves as a safety feature of this fixture; its specific structure can be found in [reference needed]. Figure 10 and Figure 11The self-alarm module 45 includes a pressure sensing component 451, which is fixedly installed on the push plate 422. The pressure sensing component 451 integrates a pressure sensor to detect the contact pressure acting on its sensitive surface in real time. An audible and visual alarm 453 is also installed on the pressure sensing component 451. The audible and visual alarm 453 is electrically connected to the pressure sensor. The pressure signal detected by the pressure sensor can be transmitted to the audible and visual alarm 453 in real time. When the pressure value exceeds the preset standard value, an alarm is triggered. A shape memory alloy drive 452 is provided on one side of the detection surface of the pressure sensor. The shape memory alloy drive 452 and the shape memory alloy elastic element 441 in the thermal self-compensation module 44 are made of the same material, that is, they have the same phase transition temperature point. One end of the shape memory alloy drive 452 abuts against the back of the clamping seat 431 and maintains good thermal contact with the clamping seat 431. Under normal operating conditions, there is a continuous flow of circulating coolant inside the clamping seat 431, and the temperature on the back of the clamping seat 431 is controlled within the normal operating range. After this temperature is conducted to the shape memory alloy drive 452, although the shape memory alloy drive 452 has entered the phase change temperature range and produced a certain deformation, a certain contact pressure is applied to the pressure sensor, but the pressure value remains within the preset standard value, and the audible and visual alarm 453 is not triggered. When the cooling system malfunctions—such as coolant interruption, pipe blockage, or abnormal operating conditions like circulation pump shutdown—causing the clamp 431 to fail to dissipate heat effectively and continuously overheat, its back surface temperature will exceed the normal operating range. At this time, the heat received by the shape memory alloy drive component 452 increases significantly, resulting in a greater degree of martensite to austenite phase transformation and generating axial expansion displacement beyond the normal range. This applies a contact pressure to the pressure sensor that far exceeds the standard value. Once the pressure sensor detects that the pressure exceeds the preset safety threshold, it outputs a signal to drive the audible and visual alarm 453 to issue an audible and visual warning, reminding on-site operators to check the cooling system in time and take appropriate measures. The self-alarm module 45 also has the following functions: timely alarm can prevent the shape memory alloy elastic element 441 from excessive expansion displacement due to continuous abnormal overheating, and prevent it from applying excessive additional thrust to the clamping seat 431, thereby protecting the contact state between the clamping seat 431 and the steel pipe surface from damage. The self-alarm module 45 and the thermal self-compensation module 44 share the same heat source for triggering, and are made of the same material with the same phase change point, ensuring that the alarm timing is accurately synchronized with the activation range of the thermal-mechanical closed-loop linkage.

[0020] Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art and related fields based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention. Structures, devices, and operating methods not specifically described and explained in the present invention, unless otherwise specified or limited, shall be implemented according to conventional means in the art.

Claims

1. A welding deformation control fixture for building steel structures, comprising: The base plate (1) serves as the mounting base and is used to support the various functional modules; The lateral clamping mechanism (4) is mounted on the base plate (1) and is used to apply clamping force from both radial sides of the steel structure component to be welded. Its features are: The lateral clamping mechanism (4) includes a cooling module (43), which has a cooling medium flow channel inside. The cooling module (43) is located between the execution end of the lateral clamping mechanism (4) and the surface of the component. The side of the cooling module (43) facing the component is the cooling contact surface. The cooling module (43) and the execution end of the lateral clamping mechanism (4) are connected by an elastic floating connection, which is achieved by a thermal self-compensation module (44) disposed between the two. The thermal self-compensation module (44) is composed of a shape memory alloy elastic element (441), with its two ends abutting against the execution end of the lateral clamping mechanism (4) and the back of the cooling module (43), respectively. The phase transformation temperature of the shape memory alloy elastic element (441) is set within the working temperature range of the component welding heat-affected zone. When the temperature reaches the phase transition point, the shape memory alloy elastic element (441) expands and displaces, pressing the cooling module (43) toward the surface of the component to reduce contact thermal resistance and enhance thermal conductivity, forming a closed-loop linkage of clamping force and cooling efficiency with positive feedback as temperature rises.

2. The anti-deformation control fixture for welded steel structures according to claim 1, characterized in that, It also includes a support mechanism (3), which is installed at the middle of the upper surface of the base plate (1) for bottom support and auxiliary limiting of the component to be welded, and has the function of adjusting the spacing along the axial direction of the component; The supporting mechanism (3) includes a support column (31), a dual-head motor (32), a lead screw (33), and a V-clamp (36). There are two support columns (31) that are spaced apart along the axial direction of the component. Their bottoms slide in a groove (2) on the upper surface of the base plate (1). The V-clamp (36) is installed on the top of the support column (31) to receive and limit the component. The dual-head motor (32) drives the lead screw (33) to move the two support columns (31) closer or further away in sync to adjust the support spacing.

3. The anti-deformation control fixture for welded steel structures according to claim 1, characterized in that, The shape memory alloy elastic element (441) is a spring sheet structure or a shape memory alloy spring, which is a helical compression spring or a disc spring assembly.

4. The anti-deformation control fixture for welded steel structures according to claim 1, characterized in that, The thermal self-compensation module (44) includes a plurality of shape memory alloy elastic elements (441), and the two ends of each shape memory alloy elastic element (441) are respectively abutted against the execution end of the lateral clamping mechanism (4) and the back of the cooling module (43) through pads (442).

5. A welding deformation control fixture for building steel structures according to claim 4, characterized in that, The phase transformation temperature of the shape memory alloy elastic element (441) is set between 80°C and 120°C, and its material is Ni-Ti alloy. The austenitic phase transformation end temperature Af is set to 90°C.

6. The anti-deformation control fixture for welded steel structures according to claim 1, characterized in that, The lateral clamping mechanism (4) includes a driving member (42), which includes a hydraulic rod (421). The piston end of the hydraulic rod (421) is fixedly connected to a push plate (422). The push plate (422) serves as the execution end of the lateral clamping mechanism (4), and a through hole (423) is provided on the push plate (422). The cooling module (43) includes a guide rod (435), one end of which is fixedly connected to the cooling module (43), and the other end is inserted into the through hole (423) on the push plate (422) and forms a sliding fit.

7. A welding deformation control fixture for building steel structures according to claim 6, characterized in that, The cooling module (43) includes a clamping seat (431), and the clamping seat (431) has an arc-shaped surface (432) machined on the side facing the component. The radius of curvature of the arc-shaped surface (432) matches the outer diameter of the component to be welded. The cooling medium flow channel is arranged in a serpentine pattern and located inside the clamping seat (431). The inlet is connected to the liquid inlet pipe (433), and the outlet is connected to the liquid outlet pipe (434). The clamping seat (431) is made of copper.

8. A welding deformation control fixture for building steel structures according to claim 6, characterized in that, The lateral clamping mechanism (4) also includes an adjustment frame (41), which includes a frame body (411) and an electric push rod (412). The frame body (411) serves as a common mounting carrier for the drive component (42), the cooling module (43), and the thermal self-compensation module (44). Its bottom is slidably engaged with the sliding groove (2) opened on the upper surface of the base plate (1). The electric push rod (412) is fixed on the base plate (1), and its telescopic end is connected to the frame body (411) to drive the frame body (411) to move along the axial direction of the component.

9. A welding deformation control fixture for building steel structures according to any one of claims 1 to 8, characterized in that, It also includes a self-alarm module (45), which is disposed between the cooling module (43) and the execution end of the lateral clamping mechanism (4), and includes a pressure sensing component (451) and a shape memory alloy drive component (452). The shape memory alloy drive (452) and the shape memory alloy elastic element (441) are made of the same material and have the same phase transition temperature. One end of the drive is attached to the back of the cooling module (43), and the other end is attached to the detection surface of the pressure sensing component (451). When the cooling module (43) overheats abnormally, the shape memory alloy drive (452) generates an axial expansion displacement that exceeds the normal operating range, applying a contact pressure exceeding the preset standard value to the pressure sensing component (451) and triggering an alarm.

10. A welding deformation control fixture for building steel structures according to claim 9, characterized in that, The pressure sensing component (451) is fixedly installed on the push plate (422). It integrates a pressure sensor and is also equipped with an audible and visual alarm (453). The audible and visual alarm (453) is electrically connected to the pressure sensor. When the pressure value exceeds the preset standard value, the audible and visual alarm is triggered.

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