Square tube centering support auxiliary welding tooling

Abstract

The utility model discloses a square tube center support auxiliary welding frock for solving the deformation problem caused by thermal stress when full penetration welding of long size square tube. Its core is a set of radial self -adaptation expansion support system, contains a pipe clamp that is driven axially to move by power assembly, and multiple sets of expansion support components that are connected in series along it, and the slight expansion and contraction of the pipe clamp drives the synchronous radial movement of the limiting support block through the linkage mechanism, after the frock hanging device enters the square tube, the expansion support components expand synchronously, the limiting support block is tightly attached to the inner wall with preset pressure, a series of uniform internal rigid support points are formed, the welding thermal stress is effectively resisted, and the geometric precision of the component is ensured, the frock integrates auxiliary structures such as mounting frame and outer moving pipe, is convenient for on -the -spot hoisting operation, and remarkably improves the welding quality and automation level.

Description

Technical Field

[0001] This utility model relates to the field of metal structural component welding manufacturing technology, and in particular to an internal support fixture for ensuring the structural dimensional stability of large thin-walled rectangular or square cross-section steel pipes (hereinafter referred to as "square pipes") during full penetration welding. Specifically, it belongs to an active anti-deformation welding auxiliary device that can be placed inside the square pipe and provide multi-point synchronous radial support from the inner wall. Background Technology

[0002] In modern industry and construction, such as large factories, rail transit stations, stadiums, bridges, and heavy machinery frames, square tubing is widely used as the main load-bearing columns and beams due to its excellent bending and torsional resistance and aesthetic appeal. The connections between these critical load-bearing components typically require full-penetration welds to ensure that the weld strength is equal to that of the base material, enabling it to withstand complex alternating loads, axial pressure, and tensile forces.

[0003] However, full penetration welding is a process of intense localized heating and cooling. The high temperature generated by the electric arc melts the butt joint area of ​​the square tube and the surrounding base material. During cooling and solidification, the shrinkage of the weld metal and the heat-affected zone generates enormous tensile stress. For closed, thin-walled box-shaped sections, this uneven shrinkage stress can easily lead to irreversible plastic deformation of the component. Common deformation modes include: longitudinal bending (bow deformation) and torsion (spiral deformation) of the overall component, as well as more localized section instability, such as sidewall concavity ("waist shrinkage") or bulging.

[0004] In the prior art, the following measures are typically taken to control welding deformation: 1. External rigid fixing method: Using large clamps to clamp the square tube from the outside to limit its deformation. This method has limited effectiveness for long components, and the clamps may obstruct the movement of the welding torch, which is particularly inconvenient for applications requiring circumferential welding. The external clamping force can sometimes even mask and accumulate internal stress, causing deformation to still occur after the stress is released when the clamps are removed.

[0005] 2. Reverse Deformation Method: Before welding, the square tube is bent in the opposite direction by an estimated amount to counteract the welding deformation. This method is highly dependent on the operator's experience, the preset amount is difficult to calculate accurately, it is not suitable for complex deformation patterns, and the process stability is poor.

[0006] 3. Traditional internal support method: Inserting wooden wedges, metal blocks, or simple adjustable struts into the square tube. These methods have few support points, and the support force is uncontrollable and uneven, failing to provide continuous and stable internal constraints. For long welds and large square tubes, the anti-deformation effect is negligible.

[0007] 4. Process parameter optimization method: This method reduces heat input by adjusting the welding sequence, current, voltage, and welding speed. While this method has some effect, it is often insufficient to completely eliminate deformation and may come at the cost of welding efficiency.

[0008] In summary, existing technologies suffer from common problems such as insufficient support, inconvenient adjustment, low automation, and poor adaptability. Particularly for welding large square tube components exceeding 6 meters in length and 400mm in cross-sectional side length, there is a lack of an efficient, reliable, and universal internal support solution. Therefore, there is an urgent need for a specialized tooling capable of providing active, uniform, and rigid support from within the component to fundamentally suppress welding deformation. Utility Model Content

[0009] The primary objective of this invention is to overcome the shortcomings of the prior art and provide a central support auxiliary welding fixture for square tubes. This fixture can be easily inserted into the interior of a square tube and provides a sufficient number of evenly distributed and controllable rigid support forces from the inner wall, effectively resisting shrinkage stress during the welding process and preventing various forms of deformation.

[0010] The secondary objective of this utility model is to provide a modular and expandable tooling design that can adapt to the welding requirements of square tubes of different lengths and cross-sectional dimensions by adjusting the number and spacing of the expansion components.

[0011] Another objective of this invention is to improve the on-site operational friendliness of the tooling by integrating the hoisting interface and counterweight system to achieve rapid and safe positioning of heavy tooling and large square tubes.

[0012] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is: a square tube center support auxiliary welding fixture, comprising: The power unit, as the power source of the tooling, provides controllable linear motion output; The clamp tube, as a core transmission component, is rigidly connected at one end to the power output end of the power assembly, and can perform precise reciprocating telescopic movement along its own axis under the drive of the power assembly. Multiple expansion and support components, as mechanisms that directly perform the support function, are coaxially and series-connected at a preset interval outside the tube body of the tube clamp. The internal mechanisms of the plurality of expansion components are mechanically coupled with the axial movement of the clamping tube, so that the unidirectional movement of the clamping tube can be converted into a synchronous radial expansion movement of all expansion components, while the reverse movement of the clamping tube drives all expansion components to perform radial contraction movement. In its expanded state, the outer contour of the expansion component is adapted to and closely fitted with the inner wall shape of the square tube to be welded, thereby providing multi-point, uniform rigid support from inside the square tube to suppress structural deformation caused by heat concentration during the welding process.

[0013] Furthermore, it also includes a rigid mounting bracket for integrating and fixing the main components of the tooling; the power assembly is firmly mounted on one side of the mounting bracket; an outer displacement tube is also fixedly connected to the mounting bracket on the side near the power assembly; the outer displacement tube is coaxially arranged with the clamping tube and is fitted with a clearance fit on the outside of the clamping tube, and its end away from the mounting bracket passes through the center of all the expansion components in sequence; the presence of the outer displacement tube does not interfere with the normal extension and retraction of the expansion components, but its tube body itself provides a stable axial positioning reference for the expansion components, and after the expansion components expand, it shares the welding stress from the square tube by combining with it.

[0014] Furthermore, a counterweight box is fixedly installed on the opposite side of the mounting frame from the side where the external tube is set. The counterweight box has reserved space inside for placing adjustable counterweight blocks. By calculating and adjusting the counterweight, the center of gravity of the entire fixture is located directly below or near the lifting point, thereby balancing the huge overturning moment generated when the square tube is sleeved on one end of the fixture, ensuring that the lifting equipment can carry out lifting and precise positioning operations smoothly and safely.

[0015] Furthermore, the specific structure of the expansion assembly is as follows: it includes a square support plate with a support hole in the center, through which the outward displacement tube passes, and the two are in a sliding fit; on each of the four sides of the support plate, two limiting pull plates are symmetrically hinged, and the top ends of the two limiting pull plates on the same side jointly support a limiting support block, which is fixedly connected to the two limiting pull plates by bolts or welding; the bottom ends of the two limiting pull plates on the same side are movably connected to one end of a rotating plate; two sets of cross-arranged connecting plates are arranged at the transverse and longitudinal center lines of the support plate, and the two ends of each set of connecting plates are movably connected to the middle of two rotating plates in opposite positions; the middle of the cross-arranged connecting plates penetrates the tube wall of the clamping tube and is linked with it; When the clamping tube moves axially relative to the outer tube and the support plate, it will drive the cross connecting plate to move. The connecting plate will then push or pull the opposite rotating plate to cause the limiting pull plates at both ends to expand or contract. Finally, the limiting support block fixed at the top of the limiting pull plate will move radially away from or towards the tooling axis, that is, expand or contract.

[0016] Furthermore, in order to provide the connecting plate with movement space and completely avoid movement interference, a long hole of a specific length and width is provided on the pipe wall of the outer tube and the clamping tube in the area corresponding to the through position of the connecting plate of each expansion component. The length direction of the long hole is parallel to the axis of the clamping tube, and its length dimension is greater than the maximum expected displacement of the connecting plate in the axial direction of the clamping tube.

[0017] Furthermore, the support portion of the limiting support block that directly contacts the inner wall of the square tube has its surface processed into an arc-shaped support surface; this arc-shaped support surface can smoothly detach from the inner wall of the square tube when contracted, reducing friction and scratches, and also facilitating the smooth insertion and removal of the tooling.

[0018] Furthermore, the power component may be a cylinder assembly, or, depending on the required support force and site conditions, a hydraulic cylinder, an electric push rod, or a ball screw mechanism driven by a servo motor.

[0019] Furthermore, the hoisting equipment is an electromagnet hoisting equipment with controllable magnetic force, which can quickly and automatically adhere to the pre-set hoisting plane on the mounting frame to achieve efficient hoisting; alternatively, mechanical hoisting tools such as hooks and rings can be used, which are connected to the mounting frame by wire ropes or chains.

[0020] Compared with existing technologies, this invention offers the following advantages: By forming a series of rigid support rings evenly distributed along the axis inside the square tube using multiple sets of expansion components, it fundamentally alters the boundary conditions of the square tube in the welding area, transforming it from a thin-walled component prone to instability into a locally reinforced quasi-rigid body. This effectively resists welding shrinkage stress and controls deformation within an extremely small range (below millimeters). This invention creatively employs a structure combining internal drive transmission of the clamping tube and connecting rod, and external centering of the outer moving tube and support plate. Power is input from the central clamping tube and converted into a uniform radial force around the perimeter through a symmetrical connecting rod mechanism, resulting in a clear and efficient power transmission path. The presence of the outer moving tube distributes most of the bending load, allowing the clamping tube to primarily bear axial force, thus optimizing the structural stress. Since all expansion components are driven by the same clamping tube, they possess natural synchronicity, ensuring that all support points contact the tube wall almost simultaneously and provide consistent support pressure, avoiding initial stress or component displacement caused by asynchronous support. The number of expansion components in this invention can be increased or decreased according to the length of the square tube to be welded. By replacing the limit support blocks of different specifications or adjusting the connecting rod ratio, it can also adapt to square tubes of different cross-sectional dimensions. This modular design greatly improves the applicability of the tooling and reduces the user's equipment investment costs. In addition, the integrated hoisting design of this utility model, namely the mounting frame, counterweight box, and hoisting equipment, allows this tooling, which may weigh several tons, to be easily and safely hoisted and accurately inserted into square tubes more than ten meters long by overhead cranes or gantry cranes, greatly reducing labor intensity and improving work efficiency and safety. This utility model mainly adopts a mechanical structure, and most of the parts are standard machined parts and standard components (such as cylinders, bearings, and pins). The structure is robust and durable, and also facilitates later inspection, replacement, and maintenance. Attached Figure Description

[0021] The present invention will be further described below with reference to the accompanying drawings.

[0022] Figure 1 This is a schematic diagram of the structure of this utility model.

[0023] Figure 2 This is a schematic diagram of the structure of this utility model without the square tube.

[0024] Figure 3 This is a partial structural diagram of the present invention with an external displacement tube.

[0025] Figure 4 This is a partial structural diagram of the present invention without the external displacement tube.

[0026] Figure 5 This is a schematic diagram of the front structure of the expansion support component in this utility model.

[0027] Figure 6This is a schematic diagram of the rear structure of the expansion component in this utility model.

[0028] In the diagram: 1 is the clamping pipe, 2 is the expansion component, 21 is the support plate, 22 is the support hole, 23 is the limiting pull plate, 24 is the limiting support block, 25 is the rotating plate, 26 is the connecting plate, 3 is the square tube, 4 is the mounting bracket, 5 is the external moving pipe, 6 is the counterweight box, 7 is the hoisting equipment, and 8 is the cylinder assembly. Detailed Implementation

[0029] The present invention will be further described below with reference to specific embodiments.

[0030] like Figures 1-6 As shown, the present invention provides a square tube center support auxiliary welding fixture, the core of which is "supporting the outside from the inside, with linkage and even distribution". It adopts a radial expansion support system based on a spatial linkage mechanism driven by the axial movement of the central tube clamp.

[0031] The tooling mainly includes a power unit, a clamping pipe 1, multiple expansion components 2, a mounting bracket 4, an external displacement pipe 5, and a counterweight box 6.

[0032] The power unit typically uses a high-thrust, precise-stroke cylinder assembly 8, which is securely mounted on a rigid mounting bracket 4. The extension and retraction of its piston rod provides the power source for the tooling operation.

[0033] The clamp tube 1 is directly connected to the piston rod of the power assembly. The power assembly drives the clamp tube 1 to make precise, small-range reciprocating movements in its axial direction.

[0034] There are multiple sets of expansion components 2, which are installed in series on the clamping tube 1 at certain intervals according to the required length of the square tube. The expansion components 2 at the end are fixed by end caps to restrict the extension of the clamping tube 1 and the outward displacement tube 5.

[0035] Each expansion assembly 2 includes a support plate 21, a limiting pull plate 23, a limiting support block 24, a rotating plate 25, and a connecting plate 26. These components together form an ingenious linkage mechanism. The axial movement of the clamping tube 1 is converted into the rotation of the rotating plate 25 through the connecting plate 26, which in turn drives the limiting pull plate 23 to open or close like scissors, ultimately causing the limiting support block 24 to expand and contract radially.

[0036] The outer tube 5 is fixed to the mounting bracket 4 and coaxially sleeved on the outside of the clamping tube 1. It runs through the support plate 21 of all the expansion components 2, acting as a centering rib. On the one hand, it provides additional rigidity support for the entire tooling front end; on the other hand, it forms a composite support structure together with the expanded limiting support block 24, greatly enhancing the constraint ability on the inner wall of the square tube.

[0037] The counterweight box 6 is installed at the rear of the mounting frame 4. When the long square tube is fitted over the front end of the tooling, it generates a huge forward tilting moment. By adding calculated counterweights inside the counterweight box 6, the center of gravity of the entire system can be shifted to below the lifting point, ensuring a stable lifting process, preventing tipping, and guaranteeing operational safety.

[0038] The working process of this utility model: 1. Lifting and positioning First, the hoisting equipment 7 is connected to the lifting point on the mounting frame 4 to lift the entire fixture. The counterweights in the counterweight box 6 are calculated and adjusted so that the center of gravity of the fixture is directly below the lifting point to balance the overturning moment generated when the square tube 3 is subsequently inserted, ensuring stable lifting.

[0039] The operator controls the hoisting equipment 7 to retract the tooling (i.e., all the limiting support blocks 24 of the expansion components 2) to the minimum outer diameter and insert them into the interior of the square tube 3 to be welded until the predetermined welding support position is reached.

[0040] 2. Starting power and internal support After the tooling is in place, the power unit (e.g., cylinder assembly 8) is activated. The power unit outputs linear motion, driving the rigidly connected clamp tube 1 to move along its own axis toward the inside of the square tube 3.

[0041] The axial movement of the clamp tube 1 drives all the series-connected expansion components 2 to move synchronously through mechanical coupling: the clamp tube 1 drives the connecting plate 26 that penetrates its tube wall to move, and the connecting plate 26 pushes the rotating plate 25 that is movably connected to it.

[0042] The rotation of the rotating plate 25 causes the limiting pull plates 23 at both ends to unfold, ultimately causing the limiting support block 24 fixed to the top of the limiting pull plate 23 to move outward in the radial direction, completing the expansion action.

[0043] During this process, the outer tube 5, as a stable axial reference, always passes through the support plate 21 of the expansion assembly 2. The elongated hole on its tube wall provides the necessary space for the movement of the connecting plate 26, thus avoiding interference.

[0044] When the arc-shaped support surfaces of all the limiting support blocks 24 of the expansion components 2 are tightly fitted with the inner wall of the square tube 3, the power component stops operating. At this time, the tooling provides multi-point, uniform, and rigid support from inside the square tube 3.

[0045] 3. Welding operations With reliable internal support from the tooling, the square tube 3 is welded. Because the limiting support block 24 abuts against the tube wall from the inside, it effectively suppresses structural deformation caused by heat concentration during the welding process, ensuring welding quality and dimensional accuracy.

[0046] The stress generated by welding is borne by the limiting support block 24, the limiting pull plate 23, and the support plate 21, and is effectively dispersed by the outer displacement pipe 5 and the mounting bracket 4.

[0047] 4. Shrinkage and Removal After welding is completed and the weld has cooled, the power unit is restarted to move the clamp tube 1 in the opposite direction (i.e., to the outside of the square tube 3).

[0048] The reverse movement of the clamp tube 1 pulls the rotating plate 25 through the connecting plate 26, causing the limiting pull plate 23 to retract, which in turn causes all the limiting support blocks 24 to retract radially, so that their arc-shaped support surfaces are no longer in contact with the inner wall of the square tube 3.

[0049] After the expansion assembly 2 has fully retracted, the entire fixture can be smoothly pulled out of the square tube 3 using the hoisting equipment 7, completing this welding auxiliary operation. The fixture is then returned to its initial state, ready for the next use.

[0050] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A square tube centering support auxiliary welding fixture, characterized by, include: The power unit, as the power source of the tooling, provides controllable linear motion output; The clamp tube (1), as the core transmission component, is rigidly connected at one end to the power output end of the power component, and can perform precise reciprocating telescopic movement along its own axis under the drive of the power component. Multiple expansion components (2), as mechanisms that directly perform the support function, are coaxially and series-connected at a preset interval outside the tube body of the card tube (1); The internal mechanism of the plurality of expansion components (2) is mechanically coupled to the axial movement of the clamp tube (1), so that the movement of the clamp tube (1) in a single direction can be converted into the synchronous radial expansion movement of all expansion components (2), while the reverse movement of the clamp tube (1) drives all expansion components (2) to perform radial contraction movement. In the expanded state, the outer contour of the expansion component (2) is adapted to and closely fits the inner wall shape of the square tube (3) to be welded, thereby providing multi-point, uniform rigid support from the inside of the square tube to suppress structural deformation caused by heat concentration during the welding process.

2. The square tube centering support and welding fixture of claim 1, wherein, It also includes a rigid mounting bracket (4) for integrating and fixing the main components of the tooling; the power assembly is firmly mounted on one side of the mounting bracket (4); the mounting bracket (4) is also fixedly connected to an external displacement tube (5) on the side near the power assembly; the external displacement tube (5) is arranged coaxially with the clamping tube (1) and is fitted with a clearance fit on the outside of the clamping tube (1), and its end away from the mounting bracket (4) passes through the center of all the expansion components (2) in sequence; the presence of the external displacement tube (5) does not interfere with the normal extension and retraction of the expansion component (2), but its tube body itself provides a stable axial positioning reference for the expansion component (2), and after the expansion component (2) expands, it shares the welding stress from the square tube (3) by combining with it.

3. The square tube centering support and welding fixture of claim 2, wherein, On the opposite side of the mounting frame (4) to the setting of the external displacement pipe (5), a counterweight box (6) is fixedly installed; the counterweight box (6) has a reserved space inside for placing an adjustable counterweight block. By calculating and adjusting the counterweight, the center of gravity of the entire tooling is located directly below or near the lifting point, thereby balancing the huge overturning moment generated when the square tube (3) is sleeved on one end of the tooling, ensuring that the lifting equipment (7) can carry out lifting and precise positioning operations smoothly and safely.

4. The square tube centering support and welding fixture of claim 2 or 3, wherein, The specific structure of the expansion component (2) is as follows: it includes a square support plate (21) with a support hole (22) in the center, through which the outer displacement tube (5) passes, and the two are in sliding fit; on each of the four sides of the support plate (21), two limiting pull plates (23) are symmetrically hinged, and the top ends of the two limiting pull plates (23) on the same side jointly support a limiting support block (24), which is fixedly connected to the two limiting pull plates (23) by bolts or welding; the bottom ends of the two limiting pull plates (23) on the same side are movably connected to one end of a rotating plate (25); two sets of cross-arranged connecting plates (26) are provided at the horizontal and vertical center lines of the support plate (21), and the two ends of each set of connecting plates (26) are movably connected to the middle of the two rotating plates (25) in opposite positions; the middle of the cross connecting plates (26) penetrates the tube wall of the clamping tube (1) and is linked with it; When the clamping tube (1) moves axially relative to the outer moving tube (5) and the support plate (21), it will drive the cross connecting plate (26) to move. The connecting plate (26) will then push or pull the opposing rotating plate (25) to drive the limiting pull plates (23) at both ends to expand or contract, and finally realize that the limiting support block (24) fixed at the top of the limiting pull plate (23) moves radially away from or close to the tooling axis, that is, expansion or contraction.

5. The square tube centering support and welding fixture of claim 4, wherein, In order to provide the connecting plate (26) with movement space and completely avoid movement interference, on the pipe wall of the outer tube (5) and the clamping tube (1), in the area corresponding to the through position of the connecting plate (26) of each expansion component (2), there is a long hole of a specific length and width. The length direction of the long hole is parallel to the axis of the clamping tube, and its length dimension is greater than the maximum expected displacement of the connecting plate (26) in the axial direction of the clamping tube.

6. The square tube centering support and welding fixture of claim 4, wherein, The support part of the limiting support block (24) that is in direct contact with the inner wall of the square tube (3) has its surface processed into an arc-shaped support surface; the arc-shaped support surface can smoothly separate from the inner wall of the square tube when it shrinks, reducing friction and scratches, and also facilitating the smooth insertion and extraction of the tooling.

7. The square tube centering support and welding fixture of claim 1, wherein, The power component may be a cylinder assembly (8), or, depending on the required support force and site conditions, a hydraulic cylinder, an electric push rod, or a ball screw mechanism driven by a servo motor.

8. The square tube centering support and welding fixture of claim 3, wherein, The hoisting equipment (7) is an electromagnet hoisting equipment with controllable magnetic force, which can quickly and automatically attach to the hoisting plane pre-set on the mounting frame (4) to achieve efficient hoisting; or it can use mechanical hoisting tools including hooks and rings, and connect to the mounting frame through wire ropes or chains.

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