Hexagonal pipe fitting welding alignment device and alignment method thereof

Abstract

The invention belongs to the technical field of hexagonal pipe fitting machining, and discloses a hexagonal pipe fitting welding alignment device and an alignment method.The hexagonal pipe fitting welding alignment device comprises a rack and a lower clamping plate installed at the bottom in the rack, the lower clamping plate is of a V-shaped structure, a lifting frame is installed at the top of the rack, and a lifting butt joint assembly is arranged in the lifting frame; a self-adjusting assembly is connected to the upper portion of the butt joint assembly. The device can be perfectly matched with the 120-degree external angle characteristic of the hexagonal pipe fitting, the micro dimensional tolerance generated in the pipe fitting machining and manufacturing process can be effectively absorbed, the clamping or clamping damage phenomenon caused by slight deformation of the pipe fitting is avoided, when the upper V-shaped clamping plate and the lower V-shaped clamping plate are completely closed, the pipe fitting can be wrapped and limited from the four faces, and the machining efficiency is improved. And the axes of the two butt joint pipe fittings are forced to coincide, high-precision coaxial alignment can be achieved without manual repeated calibration, the labor intensity of workers is greatly reduced, and the automation level of a production line is improved.

Description

Technical Field

[0001] This invention belongs to the field of hexagonal pipe processing technology, specifically a hexagonal pipe welding alignment device and its alignment method. Background Technology

[0002] Hexagonal pipe fittings, due to their unique geometric structure and mechanical properties, are widely used in building steel structures, mechanical drive shafts, fluid transportation pipelines, and decorative engineering. In the assembly process of hexagonal pipe fittings, the butt welding between fittings is a crucial step. Welding quality depends not only on the welding process parameters but also on the alignment accuracy before welding and the stability during the welding process. To ensure weld strength and appearance quality, specialized welding fixtures are typically used to fix and align the ends of the two fittings to be welded, ensuring a uniform weld and coincidence of the fitting axes.

[0003] However, existing hexagonal pipe welding alignment devices have significant limitations in practical use. First, traditional V-blocks or vise-type clamps often struggle to achieve fast and precise automatic alignment due to the unique angular shape of hexagonal pipes. Most existing clamps employ a rigid unidirectional clamping method; when the pipe has minute manufacturing tolerances, the clamps cannot adaptively adjust, causing the pipe to twist or shift its axis after the upper and lower clamps are closed. Furthermore, traditional alignment operations often rely on repeated manual fine-tuning of the pipe angle to match the clamp surface, heavily depending on human experience, cumbersome operation, and resulting in low overall assembly efficiency, making it difficult to meet the demands of large-scale automated production.

[0004] On the other hand, existing welding fixtures often neglect the thermal characteristics and operating space requirements during the welding process in their structural design. While traditional full-coverage fixtures can secure pipe fittings, they often obstruct the weld seam, preventing welders from completing multi-faceted spot welding in a single setup. This necessitates repeated disassembly, rotation, and re-clamping of the pipe fitting, severely reducing work efficiency and easily disrupting the original alignment during rotation. More seriously, existing fixtures often employ a rigid, full-process locking mechanism. During full-scale welding, the pipe fittings undergo axial and radial expansion due to high heat. The limited deformation space leads to significant residual internal stress, easily causing weld cracking or pipe deformation, severely impacting the structural strength and service life of the finished product. Summary of the Invention

[0005] The purpose of this invention is to provide a hexagonal pipe fitting welding alignment device and alignment method to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a hexagonal pipe welding alignment device, comprising a frame and a lower clamping plate installed at the bottom of the frame, the lower clamping plate having a V-shaped structure, a lifting frame installed at the top of the frame, a liftable docking assembly provided inside the lifting frame, and a self-adjusting assembly connected above the docking assembly;

[0007] The docking assembly includes left and right symmetrically arranged limiting guide rails, and the two limiting guide rails are connected by a flexible corrugated connecting wall. Two sets of left and right symmetrical upper clamping assemblies are slidably connected on the limiting guide rails. Each set of upper clamping assemblies includes two independently arranged upper clamping plates, and the two upper clamping plates are connected by an elastic telescopic rod.

[0008] The self-adjusting component is used to drive the two upper clamping plates in front and behind to move relative to each other to achieve closure, and to drive the docking component to move down as a whole. After the docking component moves down to the position, it drives the two sets of upper clamping components on the left and right sides to squeeze inward to align the pipe.

[0009] As a further technical solution of the present invention, the docking assembly also includes a limiting seat installed in the middle of the corrugated connecting wall. The limiting seat is provided with threaded seats on the front and rear sides. A lead screw passes through the two limiting guide rails laterally. The lead screw is threadedly connected to the two threaded seats and the threads at both ends are opposite in direction. A servo motor is installed on the hoisting frame to drive the lead screw to rotate. When the lead screw rotates, it drives the two limiting guide rails to move closer to each other through the threaded engagement with the threaded seats. At this time, the corrugated connecting wall connected between the limiting guide rails collapses and deforms to adapt to the change in spacing.

[0010] As a further technical solution of the present invention, the limiting card seat is movably connected to the lifting rod through the lifting ear plate, the lifting rod is fixed to the top of the lifting frame, and the upper clamping assembly also includes a mounting seat fixed to the top of the upper clamping plate. The mounting seat is provided with a guide block, and the guide block is inserted into the limiting guide rail and slides along it.

[0011] As a further technical solution of the present invention, the self-adjusting component includes a main cylinder fixed to the top of the hoisting frame, the output end of the main cylinder is connected to a longitudinal movable plate, the bottom of the longitudinal movable plate is connected to the mounting seat of the upper clamping component through a linkage mechanism, and an extension rod is vertically installed at the center of the bottom of the longitudinal movable plate, the bottom end of the extension rod is directly opposite the top surface of the limiting seat.

[0012] As a further technical solution of the present invention, the linkage mechanism includes a longitudinal link hinged to the bottom of the longitudinal movable plate, a transverse movable plate hinged to the end of the longitudinal link, a transverse link hinged to the transverse movable plate, and the end of the transverse link hinged to the mounting base.

[0013] As a further technical solution of the present invention, when the main cylinder extends, the longitudinal connecting rod pushes the two transverse movable plates to separate to both sides, thereby driving the transverse connecting rod to drive the two upper half clamping plates to overcome the resistance of the elastic telescopic rod and approach each other until they close.

[0014] As a further technical solution of the present invention, a through-hole is provided in the middle of the left and right sides of the lower clamping plate, and an clearance notch is provided in the support frame corresponding to the position of the through-hole.

[0015] As a further technical solution of the present invention, an upper through groove is provided on the relatively close side edge of the upper half clamping plates of the left and right groups. When the upper clamping components of the left and right groups are closed, the two upper through grooves are joined together to form a welding window corresponding to the position of the lower through groove.

[0016] As a further technical solution of the present invention, the included angle of the inner side of the lower clamping plate is 120 degrees, and the included angle of the inner side of the upper clamping plate after closing is 120 degrees, and the closed upper and lower clamping plates form a regular hexagonal receiving cavity.

[0017] The alignment method for the hexagonal pipe fitting welding alignment device includes the following steps:

[0018] S1. Loading and positioning: Place the two hexagonal pipe fittings to be welded on the lower clamping plate, so that the two bottom surfaces of the pipe fittings are in contact with the inner wall of the lower clamping plate, and the ends of the two pipe fittings are joined at the lower through groove;

[0019] S2. Coarse preload adjustment: Start the main cylinder to drive the longitudinal movable plate to move down, and drive the front and rear upper half clamping plates to close through the linkage mechanism. Then the extension rod presses the limit seat to make the docking assembly sink as a whole until the upper half clamping plate contacts the top of the pipe fitting.

[0020] S3. Fine Alignment: Start the servo motor to drive the lead screw to rotate, causing the corrugated connecting wall to shrink and deform, which drives the left and right limit guide rails and the upper clamping assembly to squeeze inward, and cooperate with the lower clamping plate to complete the coaxial alignment of the pipe fittings;

[0021] S4. Spot welding: The welding torch passes through the window formed by the lower through groove and the upper half through groove to perform multi-point spot welding to fix the butt joint of the pipe fitting;

[0022] S5. Pressure Relief Full Welding: Control the main cylinder to retract, remove the pressure of the upper clamping assembly on the pipe fitting, retain only the lower clamping plate support, and perform full circumference welding on the pipe fitting.

[0023] The beneficial effects of this invention are as follows:

[0024] 1. This invention, through the cooperation of self-adjusting components and docking components, abandons the traditional single rigid pressure mode. In the initial stage of operation, the cylinder drives the linkage mechanism to perform a wide range of opening and closing movements, driving the upper split V-shaped clamping plate to quickly approach the pipe fitting and complete the initial spatial positioning. Subsequently, the servo motor drives the lead screw, utilizing the collapse deformation characteristics of the flexible corrugated connecting wall to drive the limiting guide rail to perform fine lateral compression on the upper clamping plate. This mode of "coarse adjustment followed by fine adjustment, rigid approach followed by flexible fit" allows the device to perfectly adapt to the 120-degree outer angle characteristics of the hexagonal pipe fitting, effectively absorbing the micro-dimensional tolerances generated during the pipe fitting manufacturing process, and avoiding jamming or pinching caused by slight deformation of the pipe fitting. When the upper and lower V-shaped clamping plates are fully closed, they can cover and limit the pipe fitting from four sides, forcing the axes of the two docking pipe fittings to coincide. High-precision coaxial alignment can be achieved without repeated manual calibration, greatly reducing the labor intensity of workers and improving the automation level of the production line.

[0025] 2. This invention features through-slots at the joints of the lower and upper clamping plates. When the upper and lower clamping plates close to clamp the pipe fitting, these through-slots together form an annular welding operation window at the weld joint of the pipe fitting, avoiding obstruction of critical weld areas. This allows the welding equipment to directly pass through the support structure of the clamps and contact the surface of the pipe fitting. Operators can directly complete the positioning spot welding of four or more sides of the pipe fitting while maintaining a high-precision, stable clamping condition. This changes the cumbersome process of "clamping - spot welding one side - releasing - rotating - re-clamping - spot welding the other side" in the traditional process, eliminating the alignment error risk caused by releasing the clamps and rotating the pipe fitting midway. At the same time, this open design also facilitates observation of the weld alignment and real-time monitoring of the molten pool during welding, thereby significantly improving the continuity and overall efficiency of the welding operation while ensuring alignment accuracy.

[0026] 3. This invention, through a process flow of "limited spot welding - removal of upper pressure - free full welding," allows the device to quickly remove the clamping pressure from above after the pipe fittings are aligned and initially spot welded. Only the lower clamping plate remains to support the bottom of the pipe fittings. Since the pipe fittings have been connected as one piece through multi-point spot welding, they will not fall apart or misalign. However, at this time, the upper and side parts of the pipe fittings are in a state without rigid constraints. When full circumference welding is performed later, the high temperature generated by welding will cause the pipe fitting metal to undergo significant axial elongation and radial expansion. At this time, the absence of upper pressure allows the pipe fittings to freely expand and contract slightly along the axial direction, effectively releasing welding thermal stress and avoiding weld cracking or internal stress concentration caused by the clamps holding the pipe fittings. By combining mechanical fixation with thermal properties, this invention fundamentally solves the problem of easy cracking when welding thick-walled or high-strength hexagonal pipe fittings, significantly improving the qualification rate and structural reliability of the finished products. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0028] Figure 2 This is a schematic diagram showing the assembly of the frame, support frame, and lower clamping plate structure of the present invention;

[0029] Figure 3 This is a schematic diagram of the concealed frame, support frame, and lower clamping plate of the present invention;

[0030] Figure 4 This is a schematic diagram illustrating the assembly of the lifting frame, lifting rod, and docking components of the present invention.

[0031] Figure 5 This is an exploded view of the lifting rod and docking assembly structure of the present invention;

[0032] Figure 6 This is a schematic diagram showing the cooperation between the self-adjusting component, the upper clamping component, and the elastic telescopic rod structure of the present invention;

[0033] Figure 7 This is a separate schematic diagram of the self-adjusting component structure of the present invention;

[0034] Figure 8 This is an exploded view of the upper clamping assembly and the elastic telescopic rod structure of the present invention.

[0035] In the diagram: 1. Frame; 2. Support frame; 3. Lower clamping plate; 4. Lower through slot; 5. Lifting frame; 6. Lifting rod; 7. Docking assembly; 701. Limiting guide rail; 702. Corrugated connecting wall; 703. Limiting bracket; 704. Threaded seat; 705. Lifting ear plate; 706. Lead screw; 707. Servo motor; 8. Self-adjusting assembly; 801. Main cylinder; 802. Longitudinal movable plate; 803. First fixed seat; 804. Second fixed seat; 805. Longitudinal connecting rod; 806. Transverse movable plate; 807. Third fixed seat; 808. Fourth fixed seat; 809. Transverse connecting rod; 8010. Extension rod; 9. Upper clamping assembly; 901. Upper clamping plate; 902. Mounting seat; 903. Guide block; 904. Upper through slot; 10. Elastic telescopic rod. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] like Figures 1 to 8As shown, this embodiment of the invention provides a hexagonal pipe welding alignment device, including a frame 1. A support frame 2 is installed at the bottom of the inner side of the frame 1, and a lower clamping plate 3 is installed at the top of the support frame 2. The lower clamping plate 3 is a single V-shaped frame with an included angle of 120 degrees on its inner side. A fully penetrating lower through groove 4 is opened in the middle of the left and right sides of the lower clamping plate 3. A corresponding gap is opened at the bottom of the support frame 2. Specifically, a spot welding machine can be inserted into the lower through groove 4 through the gap of the support frame 2 to perform spot welding. At the same time, the top of the frame 1... A lifting frame 5 is installed on the inner side of the end. A self-adjusting component 8 is installed on the inner top wall of the lifting frame 5. Lifting rods 6 are installed on the front and rear sides of the inner top wall of the lifting frame 5. A docking component 7 is provided at the bottom of the lifting frame 5. The docking component 7 is movably connected to the lifting rods 6 near the front and rear ends. Two sets of upper clamping components 9 are symmetrically installed on the left and right sides of the bottom of the self-adjusting component 8. Each set of upper clamping components 9 includes two upper clamping components 9 symmetrically arranged front and rear. An elastic telescopic rod 10 is installed between the two upper clamping components 9 symmetrically arranged front and rear.

[0038] Among them, the elastic telescopic rod 10 is used for resetting between the two upper clamping components 9. In the initial state, the elastic telescopic rod 10 is in the longest state. At this time, the two upper clamping components 9 are not in contact and do not form a V-shaped clamping plate. When the elastic telescopic rod 10 is subjected to force, the two upper clamping components 9 can move closer to each other until they form a complete V-shaped clamping plate.

[0039] At the same time, the two sets of upper clamping components 9 on the left and right can move closer together under the action of the docking component 7, assisting the hexagonal tube below to complete the docking;

[0040] When the self-adjusting component 8 is working, it first acts on the two upper clamping components 9 at the front and rear to drive the two upper clamping components 9 to move closer to each other. After the two upper clamping components 9 contact each other, the self-adjusting component 8 applies pressure to the docking component 7, controlling the docking component 7 and the upper clamping component 9 to move down as a whole until the upper clamping component 9 contacts the top of the pipe fitting, assisting in clamping.

[0041] The docking component 7 includes two symmetrically arranged limiting guide rails 701 on the left and right, and a corrugated connecting wall 702 is installed at the relatively close end of the two limiting guide rails 701.

[0042] The corrugated connecting wall 702 is a flexible design that can undergo inward collapse deformation under force, thereby shortening the distance between the two limiting guide rails 701. A limiting seat 703 is installed in the middle of the corrugated connecting wall 702. In order to increase stability and support the docking assembly 7, lifting ear plates 705 are also installed on the front and rear sides of the limiting seat 703. The lifting ear plates 705 are movably connected to the lifting rod 6. The limiting guide rail 701 is movably connected to the upper clamping assembly 9. At the same time, a screw rod 706 is installed in the middle of the two limiting guide rails 701. The screw rod 706 passes through the limiting seat 703 and is movably connected to it. It also passes through the front and rear threaded seats 704 and is threadedly connected to them.

[0043] A return spring (not shown in the figure) is sleeved on the outer side of the lifting rod 6. The return spring is located between the lifting lug 705 and the limiting protrusion at the bottom of the lifting rod 6, and is used to lift the docking assembly 7 to the initial height without external force.

[0044] To increase the stability of the lead screw 706, the left and right ends of the lead screw 706 are movably connected to the left and right sides of the lifting frame 5. At the same time, a servo motor 707 is installed on one side of the lifting frame 5. The output end of the servo motor 707 is connected to the lead screw 706 and provides rotational power to the lead screw 706. The left and right sides of the outer side of the lead screw 706 are provided with opposite threads, and the threads inside the two thread seats 704 are in the same direction as the threads on the outer side of the lead screw 706 at the corresponding positions.

[0045] The upper clamping assembly 9 includes an upper clamping plate 901. When the two upper clamping plates 901 are in contact with each other, they can form a complete V-shaped clamping plate. The included angle of its inner side is 120 degrees, which can be adapted to the outer side of the hexagonal tube fitting. That is, the inner side of the two upper clamping plates 901 can contact one side of the hexagonal tube fitting. A mounting base 902 is installed at the top of the upper clamping plate 901. A guide block 903 is installed on one side of the mounting base 902. The guide block 903 is movably engaged with the limiting guide rail 701. The upper clamping plate 901 can move closer or further away from each other under the guidance of the guide block 903 and the limiting guide rail 701. The two mounting seats 902 are connected to both sides of the elastic telescopic rod 10. At the same time, the side of the mounting seat 902 away from the guide block 903 is connected to the self-adjusting component 8. The self-adjusting component 8 drives the two upper clamping components 9 to move closer to each other and the entire upper clamping components 9 to move downward. Meanwhile, the upper through grooves 904 are opened at the relatively close ends of the left and right upper clamping plates 901.

[0046] Specifically, after the two upper clamping plates 901 make contact with each other and complete the docking, and the bottom ends of the two upper clamping plates 901 make contact with the outer surfaces of the two hexagonal tubes to be docked, the docking process of the hexagonal tubes can begin. That is, the servo motor 707 is turned on to drive the lead screw 706 to rotate, which in turn drives the two threaded seats 704 to move closer together, and simultaneously drives the two limit guide rails 701 to move closer together. The two limit guide rails 701 can then drive the two upper clamping plates 901 to move closer together until the two upper clamping plates 901 make contact with each other. At this point, under pressure, the two hexagonal tubes are driven closer together until the docking process of the two hexagonal tubes is completed.

[0047] The self-adjusting assembly 8 includes a main cylinder 801. The top of the main cylinder 801 is connected to the middle of the inner top wall of the hoisting frame 5. A longitudinal movable plate 802 is installed at the output end of the main cylinder 801. First fixed seats 803 are installed on the left and right sides of the bottom end of the longitudinal movable plate 802. A longitudinal connecting rod 805 is installed at the end of the first fixed seat 803 away from the longitudinal movable plate 802 via a rotating shaft. A second fixed seat 804 is installed at the end of the longitudinal connecting rod 805 away from the first fixed seat 803 via a rotating shaft. At the bottom of 4, a transverse movable plate 806 is installed. At the front and rear ends of the two transverse movable plates 806 that are relatively close to each other, a third fixed seat 807 is installed. At the end of the third fixed seat 807 away from the transverse movable plate 806, a transverse connecting rod 809 is installed through a pivot. At the end of the transverse connecting rod 809 away from the third fixed seat 807, a fourth fixed seat 808 is installed through a pivot. The fourth fixed seat 808 is connected to one end of the mounting base 902. An extension rod 8010 is installed in the middle of the bottom of the longitudinal movable plate 802.

[0048] Specifically, when the deflection angle of the longitudinal link 805 is at its maximum value, the distance between the two transverse movable plates 806 is at its maximum value, and the deflection angle of the transverse link 809 is at its minimum value, which causes the two upper half clamping plates 901 to come into contact with each other. At this time, the bottom end of the extension rod 8010 comes into contact with the top end of the limit seat 703.

[0049] When the two sets of upper half plates 901 on the left and right sides come into contact with each other, the two upper half through slots 904 on the left and right sides form an annular through slot, which corresponds to the lower through slot 4.

[0050] Example: When aligning and welding hexagonal tubes, first place the two hexagonal tubes to be joined on the lower clamping plate 3, with the ends of the two hexagonal tubes to be joined corresponding to each other. Keep the two outer sides of the hexagonal tubes in contact with the two inner sides of the lower clamping plate 3 to complete the placement process of the hexagonal tubes. Keep the top of the hexagonal tubes in slight contact with the inner side of the upper clamping plate 901, but not in complete contact.

[0051] After placement, the main cylinder 801 can be activated. At this time, the main cylinder 801 extends, causing the longitudinal movable plate 802 to move downward and causing the two longitudinal connecting rods 805 at the bottom to deflect in a direction away from each other. At this time, the two transverse movable plates 806 move away from each other, increasing the transverse misalignment between the transverse movable plate 806 and the upper clamping plate 901. Since the length of the transverse connecting rod 809 is fixed, this transverse displacement pulls the transverse connecting rod 809 to deflect, forcing the two upper clamping plates 901 to overcome the resistance of the elastic telescopic rod 10 and move closer to each other in the front-back direction under the guidance of the docking assembly 7 until the two upper clamping plates 901 come into contact and close. At this time, the hexagonal tube at the bottom can be limited, causing the hexagonal tube to roll slightly to complete the auxiliary alignment process.

[0052] At this point, the extension rod 8010 descends to its lowest point and applies pressure to the bottom docking assembly 7. The structure at the bottom of the main cylinder 801, as well as the docking assembly 7 and the upper clamping assembly 9, move downward as a whole. The gap between the upper clamping assembly 9 and the lower clamping plate 3 decreases until the inner side of the upper clamping plate 901 is in complete contact with the outer side of the hexagonal tube. At this point, the other four sides of the hexagonal tube, except for the two sides on the left and right, are in close contact with the inner sides of the upper clamping plate 901 and the lower clamping plate 3, completing the alignment process of the two hexagonal tubes.

[0053] By utilizing the cooperation between the docking component 7, the self-adjusting component 8, and the upper clamping component 9, and by setting a separable V-shaped clamping plate on the top and an integral V-shaped clamping plate on the bottom, when the hexagonal pipe is placed on the lower clamping plate 3, the relative proximity of the two upper clamping components 9 can complete the fine adjustment and alignment process of the hexagonal pipe. The downward pressure of the upper clamping component 9 can quickly complete the limiting and clamping process of the pipe. The entire process only requires the self-adjusting component 8 to drive, which effectively shortens the alignment time and improves the overall welding efficiency.

[0054] Example: After the two hexagonal tubes are joined by the joining assembly 7, the annular groove formed by the lower through groove 4 and the two upper half through grooves 904 can be located at the joining point of the two hexagonal tubes. Since the joining of the hexagonal tubes has been completed, the welding end of the electric welding machine can be inserted into the lower through groove 4 and the annular groove. At this time, the electric welding process of the four sides of the hexagonal tubes can be completed. Then the device can be released from the top limit of the hexagonal tubes, and the subsequent full welding process can be carried out.

[0055] By reusing the limiting clamping process on the four sides of the device, the spot welding machine can pass through the annular through groove composed of the lower through groove 4 and two upper half through grooves 904, realizing a rapid spot welding process on the four sides without affecting the alignment and docking process. After the spot welding is completed, the upper limit is removed, and only the lower support is provided, so that the remaining weld and the previously spot welded areas can be fully welded around the circumference. Since the pipe is already spot welded and fixed, the pipe will not fall apart. Since there is no pressure on the upper part, the pipe can freely expand and contract slightly along the axis during the high thermal expansion generated by the subsequent full welding, avoiding weld cracking or residual internal stress caused by rigid clamping, and improving the overall welding quality.

[0056] To further illustrate the mechanical advantages of the self-adjusting component 8 during the clamping process, the following kinematic model was established for verification:

[0057] Let the length of the longitudinal connecting rod 805 be L1, the length of the transverse connecting rod 809 be L2, and the downward thrust output by the main cylinder 801 be Fin. At this time, the angle between the longitudinal connecting rod 805 and the vertical direction is α, and the angle between the transverse connecting rod 809 and the horizontal direction (i.e. the direction of movement of the transverse movable plate 806) is β.

[0058] Under ideal conditions where friction is ignored, based on the principle of virtual work and the geometric relationship of the mechanism, the transmission relationship between the lateral clamping force Fclamp generated by the upper clamping plate 901 on the pipe and the cylinder thrust Fin can be approximately expressed as:

[0059]

[0060] According to the formula, as the main cylinder 801 pushes downward, the longitudinal movable plate 802 moves downward, and the angle α gradually increases (cot(α) decreases). At the same time, the transverse movable plate 806 moves outward, causing the transverse connecting rod 809 to deflect, which makes the angle β gradually increase (tan(β) increases).

[0061] Preferably, in this embodiment, the mechanism parameters are set in the initial state such that at the instant of closing the contact tube (i.e., the clamping point), the α value is close to 45° and the β value is relatively large (close to 60° to 75°). At this time, the aforementioned transmission ratio coefficient...

[0062]

[0063] It will be significantly improved.

[0064] Through this linkage force amplification mechanism, the upper clamping plate 901 has a faster moving speed in the initial stage (α is small, β is small), which can quickly complete the "coarse pre-compression". In the clamping stage after contacting the pipe, the moving speed decreases, but the clamping force Fclamp increases nonlinearly and sharply. This "slow speed and high torque" end characteristic can ensure that a huge corrective force sufficient to overcome the elastic deformation of the pipe is obtained without increasing the selection specifications of the main cylinder 801, thereby achieving forced alignment of the thick-walled hexagonal pipe.

[0065] The comparative test experiment is as follows:

[0066] 1. Experimental conditions: Standard hexagonal steel pipes made of Q345B with an outer diameter of 100mm and a wall thickness of 5mm were selected as samples. 50 pairs of pipe fittings were welded in each group of experiments.

[0067] 2. Experimental Groups:

[0068] Control group A (traditional process): using a regular bench vise in conjunction with manual marking and alignment, and adopting the traditional process of "spot welding - loosening and flipping - spot welding".

[0069] Control group B (rigid tooling): Uses an integrated rigid hexagonal mold (without flexible fine-tuning function), fully enclosed and clamped before welding.

[0070] Experimental group (invention): The welding alignment device described in this embodiment was used and operated according to the steps of S1-S5.

[0071] 3. Test metrics and data statistics:

[0072] Average time for single-piece alignment: The average time from material loading to completion of spot welding and fixing.

[0073] Coaxiality error: After welding, measure the maximum deviation of the axes of the two pipe fittings.

[0074] Weld cracking rate: The proportion of samples with cracks detected by flaw detection after full welding and cooling.

[0075] The experimental results are shown in the table below:

[0076]

[0077] 4. Results Analysis:

[0078] In terms of efficiency, this invention eliminates the time spent on repeated manual tapping and calibration through the automated linkage of "coarse adjustment + fine adjustment", and the design of the annular welding window avoids the process of flipping the pipes midway, which greatly shortens the cycle time.

[0079] In terms of accuracy, although control group B is faster, it cannot adapt to the tolerance of pipe fittings, resulting in some non-standard pipe fittings being forcibly clamped crooked; while the flexible adaptability provided by the corrugated connecting wall 702 of the present invention allows the coaxiality error to be controlled within 0.1mm.

[0080] In terms of quality, the cracking rate of control group B was the highest, which confirmed that the rigid constraint would prevent the release of welding thermal stress. The strategy of removing the upper pressure in the "pressure relief full welding" of this invention successfully solved this problem, reducing the cracking rate to 0%.

[0081] The alignment method of the hexagonal pipe fitting welding alignment device is characterized by comprising the following steps:

[0082] S1. Loading and positioning: Place the two hexagonal pipe fittings to be welded on the lower clamping plate 3, so that the two bottom surfaces of the pipe fittings are in contact with the inner wall of the lower clamping plate 3, and the ends of the two pipe fittings are joined at the lower through groove 4.

[0083] S2. Coarse pre-pressure adjustment: Start the main cylinder 801 to drive the longitudinal movable plate 802 to move down, and drive the two upper half clamping plates 901 to close through the linkage mechanism. Then the extension rod 8010 presses the limit card seat 703 to make the docking assembly 7 sink down as a whole until the upper half clamping plate 901 contacts the top of the pipe.

[0084] S3. Fine Alignment: Start the servo motor 707 to drive the lead screw 706 to rotate, causing the corrugated connecting wall 702 to shrink and deform, which drives the left and right limit guide rails 701 and the upper clamping assembly 9 to press inward, and cooperate with the lower clamping plate 3 to complete the coaxial alignment of the pipe fittings.

[0085] S4. Positioning spot welding: The welding torch passes through the window formed by the lower through groove 4 and the upper half through groove 904 to perform multi-point spot welding to fix the pipe fitting joint;

[0086] S5. Pressure Relief Full Welding: Control the main cylinder 801 to retract, remove the pressure of the upper clamping assembly 9 on the pipe fitting, leaving only the lower clamping plate 3 for support, and perform full circumference welding on the pipe fitting.

Claims

1. A hexagonal pipe fitting welding alignment device, comprising a frame (1) and a lower clamping plate (3) installed at the bottom of the frame (1), the lower clamping plate (3) having a V-shaped structure, characterized in that: A lifting frame (5) is installed on the top of the frame (1), and a lifting docking assembly (7) is provided inside the lifting frame (5). A self-adjusting assembly (8) is connected above the docking assembly (7). The docking assembly (7) includes left and right symmetrically arranged limiting guide rails (701), and the two limiting guide rails (701) are connected by a flexible corrugated connecting wall (702). Two sets of left and right symmetrical upper clamping assemblies (9) are slidably connected on the limiting guide rails (701). Each set of upper clamping assemblies (9) includes two independently arranged upper half clamping plates (901) at the front and back. The two upper half clamping plates (901) at the front and back are connected by an elastic telescopic rod (10). The self-adjusting component (8) is used to drive the two upper clamping plates (901) to move relative to each other to achieve closure, and to drive the docking component (7) to move down as a whole. The docking component (7) is used to drive the two upper clamping components (9) on the left and right sides to squeeze inward to align the pipe after moving down to the position.

2. The hexagonal pipe fitting welding alignment device according to claim 1, characterized in that: The docking assembly (7) also includes a limiting seat (703) installed in the middle of the corrugated connecting wall (702). The limiting seat (703) has threaded seats (704) on both the front and rear sides. A lead screw (706) runs horizontally between the two limiting guide rails (701). The lead screw (706) is threadedly connected to the two threaded seats (704) with opposite threads at both ends. A servo motor (707) is installed on the hoisting frame (5) to drive the lead screw (706) to rotate. When the lead screw (706) rotates, it drives the two limiting guide rails (701) to move closer to each other through the threaded engagement with the threaded seats (704). At this time, the corrugated connecting wall (702) connected between the limiting guide rails (701) collapses and deforms to adapt to the change in spacing.

3. The hexagonal pipe fitting welding alignment device according to claim 2, characterized in that: The limiting bracket (703) is movably connected to the lifting rod (6) through the lifting ear plate (705). The lifting rod (6) is fixed to the top of the lifting frame (5). The upper clamping assembly (9) also includes a mounting seat (902) fixed to the top of the upper clamping plate (901). The mounting seat (902) is provided with a guide block (903). The guide block (903) is inserted into the limiting guide rail (701) and slides along it.

4. The hexagonal pipe fitting welding alignment device according to claim 3, characterized in that: The self-adjusting assembly (8) includes a main cylinder (801) fixed on the top of the hoisting frame (5). The output end of the main cylinder (801) is connected to a longitudinal movable plate (802). The bottom of the longitudinal movable plate (802) is connected to the mounting base (902) of the upper clamping assembly (9) through a linkage mechanism. An extension rod (8010) is also vertically installed at the center of the bottom of the longitudinal movable plate (802). The bottom end of the extension rod (8010) is directly opposite the top surface of the limiting seat (703).

5. The hexagonal pipe fitting welding alignment device according to claim 4, characterized in that: The linkage mechanism includes a longitudinal link (805) hinged to the bottom of the longitudinal movable plate (802), the end of the longitudinal link (805) is hinged to a transverse movable plate (806), a transverse link (809) is hinged to the transverse movable plate (806), and the end of the transverse link (809) is hinged to the mounting base (902).

6. The hexagonal pipe fitting welding alignment device according to claim 5, characterized in that: When the main cylinder (801) extends, the longitudinal connecting rod (805) pushes the two transverse movable plates (806) to separate to both sides, thereby driving the transverse connecting rod (809) to drive the two upper clamping plates (901) to overcome the resistance of the elastic telescopic rod (10) and move closer to each other until they close.

7. The hexagonal pipe fitting welding alignment device according to claim 1, characterized in that: The lower clamping plate (3) has through slots (4) in the middle of its left and right sides, and the support frame (2) has clearance notches corresponding to the lower slots (4).

8. The hexagonal pipe fitting welding alignment device according to claim 7, characterized in that: The upper half clamping plates (901) of the left and right groups are provided with upper half through grooves (904) on the relatively close side edges. When the upper clamping components (9) of the left and right groups are closed, the two upper half through grooves (904) are joined together to form a welding window corresponding to the position of the lower through groove (4).

9. The hexagonal pipe fitting welding alignment device according to claim 1, characterized in that: The included angle of the inner side of the lower clamping plate (3) is 120 degrees, and the included angle of the inner side of the upper clamping plate (901) after closing is 120 degrees. The closed upper and lower clamping plates form a regular hexagonal cavity.

10. An alignment method for a hexagonal pipe fitting welding alignment device as described in any one of claims 1 to 9, characterized in that: Includes the following steps: S1. Loading and positioning: Place the two hexagonal pipe fittings to be welded on the lower clamping plate (3), so that the two bottom surfaces of the pipe fittings are in contact with the inner wall of the lower clamping plate (3), and the ends of the two pipe fittings are joined at the lower through groove (4); S2. Coarse pre-pressure adjustment: Start the main cylinder (801) to drive the longitudinal movable plate (802) to move down, and drive the two upper half clamps (901) to close through the linkage mechanism. Then the extension rod (8010) presses the limit seat (703) to make the docking assembly (7) sink down as a whole until the upper half clamp (901) contacts the top of the pipe fitting. S3. Fine alignment: Start the servo motor (707) to drive the lead screw (706) to rotate, causing the corrugated connecting wall (702) to shrink and deform, driving the left and right limit guide rails (701) and the upper clamping assembly (9) to squeeze inward, and cooperate with the lower clamping plate (3) to complete the coaxial alignment of the pipe fittings; S4. Positioning spot welding: The welding torch passes through the window formed by the lower through groove (4) and the upper half through groove (904) to fix the pipe fitting joint by multiple spot welding; S5. Pressure relief full welding: Control the main cylinder (801) to retract, remove the pressure of the upper clamping assembly (9) on the pipe fitting, and retain only the lower clamping plate (3) for support, and perform full circumference welding on the pipe fitting.

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