Positioning tool for pipe welding

Abstract

This invention discloses a positioning fixture for pipe welding, relating to the technical field of auxiliary equipment for pipe welding. The fixture includes a base plate, a limiting ring, a positioning mechanism, and a ventilation mechanism. The positioning mechanism includes a drive assembly and a quick-release assembly. The drive assembly drives the limiting ring to move vertically, and the quick-release assembly allows for the rapid assembly and disassembly of the limiting ring. The quick-release assembly includes a positioning rod and a spring sleeved on the outside of the positioning rod. Under the preload of the spring, the positioning rod inserts into the protrusion of the limiting ring to achieve elastic clamping. The ventilation mechanism is used to extract and filter welding fumes. This invention achieves precise lifting and lowering of the limiting ring through a dual-motor drive, avoiding ring deformation caused by uneven screw tightening force in traditional methods.

Description

Technical Field

[0001] This invention relates to the field of auxiliary equipment for pipeline welding, and specifically to a positioning fixture for pipeline welding. Background Technology

[0002] Flange pipes are pipe connection structures formed by welding pipes and rings, and are widely used in various piping systems. During the welding process of flange pipe assemblies, the rings are prone to deformation, thus requiring the use of positioning fixtures to fix them. Most existing positioning fixtures use a method of placing the ring between two pressure plates and then tightening it with four screws. However, this method has the following problems: Firstly, it is difficult to maintain a consistent tightening force among the four screws, and uneven compressive stress can cause deformation of the ring, especially for thin-walled rings, which may even produce microscopic indentations on their inner surface, affecting product yield. Secondly, the screw-tightening method has low assembly and disassembly efficiency, and repeated tightening can easily cause thread wear, further affecting the service life and positioning accuracy of the fixture. Summary of the Invention

[0003] This invention provides a positioning fixture for pipe welding, which aims to solve the technical problems of uneven screw tightening force leading to ring deformation and low disassembly and assembly efficiency in existing positioning fixtures.

[0004] To achieve the above objectives, the positioning fixture for pipe welding provided by the present invention includes a base plate, a limiting ring, a positioning mechanism, and a ventilation mechanism. The positioning mechanism includes a drive assembly and a quick-release assembly. The drive assembly drives the limiting ring to reciprocate vertically, and the quick-release assembly detachably mounts the limiting ring onto the drive assembly. The ventilation mechanism draws in and filters fumes generated during welding. The quick-release assembly includes a positioning rod and a spring. The spring is sleeved on the outside of the positioning rod, and the positioning rod, under the elastic preload of the spring, inserts into a protrusion on the limiting ring to achieve elastic clamping.

[0005] Furthermore, the drive assembly includes a threaded rod and a connecting plate. The connecting plate is threaded onto the outside of the threaded rod, and when the threaded rod rotates, it drives the connecting plate to move the limiting ring up and down.

[0006] Furthermore, the positioning fixture for pipe welding also includes a support frame, which is disposed at the top of the base plate. A guide groove is provided through the support frame, and the connecting plate movably passes through the guide groove and moves along it.

[0007] Furthermore, motors are installed on both sides of the support frame, and the bottom end of the threaded rod is connected to the output end of the motor, which drives the rod to rotate.

[0008] Furthermore, a guide seat is provided at the top of the connecting plate, the positioning rod is movably disposed within the guide seat, and one end of the spring is connected to the guide seat.

[0009] Furthermore, the exhaust mechanism includes an exhaust shell, an activated carbon plate, and a fan. The exhaust shell is located at the bottom of the support frame, the fan communicates with the interior of the exhaust shell through a through groove, and the activated carbon plate is located inside the exhaust shell for filtering welding fumes.

[0010] Furthermore, the inner wall of the exhaust casing is provided with a limiting plate, and the activated carbon plate is detachably installed between the limiting plates.

[0011] Furthermore, the top of the support frame is provided with a mounting shell, the fan is disposed inside the mounting shell, and the mounting shell is connected to the exhaust shell through the through groove.

[0012] Furthermore, the protrusion at the top of the limiting ring is provided with a hole for the positioning rod to be inserted. The positioning rod is inserted into the hole under the action of the spring to clamp and fix the limiting ring.

[0013] Furthermore, the quick-release assembly is configured in two sets, with the two sets of positioning rods inserted into the protrusions of the limiting ring from both sides to form a double-sided elastic clamping.

[0014] The advantages and beneficial effects of this invention are as follows: The positioning fixture for pipe welding provided by this invention achieves lifting control of the limit ring by setting a drive assembly including a dual-motor driven threaded rod and a connecting plate, replacing the traditional method of manually tightening screws, eliminating the tightening force deviation caused by human operation, and effectively avoiding deformation and micro-indentation of the ring due to non-uniform compressive stress; By setting a quick-release assembly including a spring and a positioning rod, the elastic preload of the spring is used to make the positioning rod automatically insert and press against the protrusion of the limit ring, achieving elastic clamping. Disassembly and assembly can be completed by simply overcoming the spring force to pull out the positioning rod, while avoiding the thread wear problem caused by repeated tightening of traditional threaded connections, thus extending the service life of the fixture; In addition, by integrating a ventilation mechanism with a fan, a through groove and a removable activated carbon plate, the fumes generated during welding can be effectively extracted and filtered, improving the working environment. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic cross-sectional view of the support frame structure of the present invention; Figure 3 This is a schematic diagram of the limiting ring structure of the present invention; Figure 4 This is an exploded view of the connecting plate and protrusion structure of the present invention; Figure 5 For the present invention Figure 2 A magnified schematic diagram of the local structure at point A.

[0016] The component names corresponding to each mark in the attached diagram are as follows: 1-Base plate; 2-Support frame; 3-Guide groove; 4-Threaded rod; 5-Motor; 6-Connecting plate; 7-Guide seat; 8-Positioning rod; 9-Spring; 10-Limiting ring; 11-Protrusion; 12-Exhaust shell; 13-Limiting plate; 14-Activated carbon plate; 15-Through groove; 16-Mounting shell; 17-Fan. Detailed Implementation

[0017] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application will be described in detail below with reference to the accompanying drawings. It is to be understood that the specific embodiments described herein are merely illustrative of this application and not intended to limit it. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0018] The terms “comprising” and “having”, and any variations thereof, used in this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus.

[0019] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly or implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0020] like Figures 1 to 5 As shown, this invention provides a positioning fixture for pipe welding, mainly used for positioning and clamping pipe fittings and ring fittings during welding in a flanged pipe assembly. A flanged pipe refers to a pipe fitting structure in which the end of a pipe is folded outwards to form a flange-like connection surface through mechanical or thermal processing methods. It consists of two parts: a pipe and a ring fitting. After the pipe and ring fitting are welded together, a complete flanged pipe is formed. During the welding process, due to the thermal stress generated by the welding heat input, the ring fitting, especially thin-walled ring fittings, is prone to warping deformation. Therefore, a positioning fixture is needed to constrain the ring fitting to control its deformation.

[0021] The positioning fixture for pipe welding provided by this invention includes a base plate 1, a limiting ring 10, a positioning mechanism, and a ventilation mechanism. The base plate 1 is the basic load-bearing component of the fixture, and a support frame 2 is fixedly installed on its top. The support frame 2 is the main frame of the fixture, used to support and install the various functional components of the positioning mechanism and the ventilation mechanism. The support frame 2 can be welded from metal square tubing or steel plates. The support frame 2 should have sufficient vertical height to provide ample travel for the vertical lifting and lowering of the limiting ring 10. Inside the support frame 2, two sets of guide grooves 3 are vertically oriented. The cross-sectional shape of the guide grooves 3 can be rectangular, U-shaped, or T-shaped. The direction of the guide grooves 3 should be perpendicular to the upper plane of the base plate 1 to ensure that the limiting ring 10 does not shift horizontally during lifting and lowering, thereby ensuring the coaxiality between the ring and the pipe.

[0022] The top central area of ​​the base plate 1 is used to place the ring and tube of the flanged tube assembly to be welded. Specifically, the ring is placed flat on the upper surface of the base plate 1, and the tube is inserted vertically into the inner hole of the ring, with the flanged end of the tube contacting the upper surface of the ring to form the weld seam to be welded. During the welding process, the ring needs to be pressed and fixed by the limiting ring 10 to prevent it from warping and deforming under thermal stress.

[0023] The limiting ring 10 is an annular component with an inner diameter larger than the outer diameter of the pipe but smaller than the outer diameter of the ring. This means the projection of the bottom surface of the limiting ring 10 in the vertical direction at least partially overlaps with the upper surface of the ring, allowing the limiting ring 10 to apply a vertically downward clamping force to the ring from above. The limiting ring 10 is preferably made of the same or similar metal material as the ring to reduce additional stress caused by differences in thermal expansion coefficients. A protrusion 11 is fixedly provided at the top of the limiting ring 10. The number of protrusions 11 is the same as the number of positioning rods 8 in the quick-release assembly; in this embodiment, two protrusions are provided, respectively located on opposite sides of the top of the limiting ring 10. The protrusions 11 can be fixed to the limiting ring 10 by welding or integral molding. Each protrusion 11 has a positioning hole for the insertion of the positioning rod 8, the horizontal axis of which is aligned with the direction of movement of the positioning rod 8.

[0024] The positioning mechanism includes a drive assembly and a quick-release assembly. The drive assembly provides the power for the vertical lifting and lowering of the limit ring 10, and mainly consists of a threaded rod 4 and a connecting plate 6. The threaded rod 4 is a long rod with external threads machined on its outer surface. The thread profile is preferably trapezoidal or rectangular, as these threads have higher transmission efficiency and better self-locking performance, ensuring that the limit ring 10 can reliably stop at any lifting or lowering position without slipping. The connecting plate 6 has a plate-like structure, with an internal threaded hole at one end that mates with the external thread of the threaded rod 4. The connecting plate 6 is threaded onto the outside of the threaded rod 4 through this internal threaded hole. When the threaded rod 4 rotates around its own axis, the connecting plate 6 can only move linearly along the axial direction of the threaded rod 4 because its rotational freedom is constrained by the guide groove 3. A limit retaining ring can be installed at the upper end of the threaded rod 4 to prevent the connecting plate 6 from dislodging, and the lower end of the threaded rod 4 is connected to the output end of the motor 5.

[0025] Two motors 5 are installed on both sides of the support frame 2, corresponding to two sets of threaded rods 4 and connecting plates 6 respectively. The two motors 5 are preferably synchronous motors, meaning they can start, run, and stop synchronously when energized. To achieve strict synchronization, the two motors 5 can be connected in parallel to the same drive controller, which outputs the same drive signal to control the operation of both motors simultaneously. Preferably, both motors 5 are stepper motors or servo motors. The motors 5 can be fixedly mounted on the bottom or side of the support frame 2 using motor mounting brackets.

[0026] When the two sets of motors 5 synchronously drive the two threaded rods 4 to rotate in the same direction and at the same speed, the two threaded rods 4 synchronously drive the two connecting plates 6 to rise or fall synchronously along their respective guide grooves 3. The two connecting plates 6 are connected as one unit by a limiting ring 10, so the limiting ring 10 achieves smooth vertical lifting and lowering movement under the synchronous drive of the two connecting plates 6. By controlling the rotation direction and number of rotations of the motors 5, the lifting direction and displacement of the limiting ring 10 can be precisely controlled, thereby precisely adjusting the clamping force applied by the limiting ring 10 to the ring component.

[0027] The quick-release assembly is used to quickly install or remove the limiting ring 10 from the drive assembly. It mainly includes a positioning rod 8 and a spring 9. The positioning rod 8 is a slender cylindrical rod with a guide cone or chamfer at its front end to facilitate insertion into the positioning hole on the protrusion 11. A pull ring or handle can be provided at the rear end of the positioning rod 8 for easy gripping and force application by the operator. The spring 9 is sleeved on the outside of the positioning rod 8, and is preferably a cylindrical helical compression spring. A guide seat 7 is fixedly installed at the top of the connecting plate 6. The guide seat 7 has a block-shaped structure with a through guide hole. The positioning rod 8 is movably inserted through the guide hole of the guide seat 7. The guide hole and the positioning rod 8 are in clearance fit, preferably controlled between 0.1mm and 0.3mm, ensuring that the positioning rod 8 can slide freely within the guide hole while maintaining consistent movement direction.

[0028] One end of the spring 9 is connected to one side of the guide seat 7, and the other end of the spring 9 is connected to the rod body of the positioning rod 8, specifically to an annular boss or retaining ring on the rod body of the positioning rod 8. In its natural state, the spring 9 is in a compressed or pre-stretched state, and its elastic force drives the positioning rod 8 to move closer to the limiting ring 10. When the two protrusions 11 of the limiting ring 10 are aligned with the two positioning rods 8, under the elastic pre-tightening force of the spring 9, the two positioning rods 8 automatically insert into the positioning holes of the two protrusions 11 from both sides, thereby locking the limiting ring 10 onto the connecting plate 6. Since the two positioning rods 8 are simultaneously inserted into the positioning holes from both sides, a double-sided elastic clamping structure is formed, and the limiting ring 10 is reliably constrained in both the horizontal and vertical directions.

[0029] When it is necessary to remove the limiting ring 10, the operator only needs to hold the pull ring or handle at the rear end of the positioning rod 8, overcome the elastic force of the spring 9, and pull the positioning rod 8 away from the limiting ring 10, so that the front end of the positioning rod 8 exits from the positioning hole of the protrusion 11, thereby releasing the lock on the limiting ring 10. The limiting ring 10 can then be lifted upwards to complete the removal.

[0030] The exhaust system is used to draw in and filter the high-temperature fumes generated during welding. Welding fumes are a mixture of solid aerosol particles and gaseous pollutants formed by the evaporation, oxidation, and condensation of metal materials during high-temperature welding. Their temperature typically reaches hundreds of degrees Celsius, and they contain a large number of micron- and submicron-sized metal oxide particles as well as toxic and harmful gases. If welding fumes are directly released into the workshop environment without treatment, they will not only severely pollute the air at the work site but also damage the respiratory health of the operators. In this invention, the exhaust system specifically includes an exhaust housing 12, an activated carbon plate 14, and a fan 17.

[0031] A through-slot 15 is vertically pierced through the upper and lower walls of the support frame 2. An exhaust housing 12 is located at the bottom of the support frame 2, above the base plate 1, and has a reserved space between it and the base plate 1 to accommodate rings and pipes. This space is used to place the pipes and rings to be welded, and welding operations are performed within this space, where welding fumes are also primarily generated. The upper end of the exhaust housing 12 is connected to the lower opening of the through-slot 15, and the inner cavity of the exhaust housing 12 is connected to the space above the support frame 2 via the through-slot 15. The exhaust housing 12 has a hollow shell structure, with its lower end open as a suction port facing the welding area to draw in welding fumes. The exhaust housing 12 preferably adopts a funnel-shaped or tapered structure, meaning its lower opening area is larger to cover the welding area, and its upper opening area is smaller to connect with the through-slot 15. This tapered structure helps to improve the flow rate and suction efficiency of the intake airflow.

[0032] The inner wall of the exhaust casing 12 is fixedly provided with limiting plates 13. There are four sets of limiting plates 13, i.e., two pairs. Each pair of limiting plates 13 is disposed opposite to two opposite inner walls of the exhaust casing 12, forming an installation groove between the two pairs of limiting plates 13. The activated carbon plate 14 is detachably installed in the installation groove. The limiting plates 13 can be made of L-shaped angle steel or rectangular steel bars, and are fixed to the inner wall of the exhaust casing 12 by welding or bolting. The activated carbon plate 14 has a flat plate structure, and its outer perimeter is adapted to the internal contour of the exhaust casing 12. The activated carbon plate 14 is composed of a plate-shaped frame and activated carbon particles filled in the frame. The frame can be made of metal wire mesh or stainless steel perforated plate.

[0033] When the fumes generated during welding are drawn into the exhaust casing 12 from the generation area, their temperature is typically between 200°C and 600°C, depending on the welding process parameters, the type of welding material, and the environmental heat dissipation conditions. When the high-temperature fumes come into contact with the activated carbon plate 14, the tiny channels between the activated carbon particles create a large heat exchange area, resulting in intense convective and conductive heat transfer between the high-temperature fumes and the surface of the activated carbon particles. This rapidly reduces the fumes temperature to below 50°C. The temperature reduction accelerates the condensation of metal vapors in the fumes into solid particles, which are more easily intercepted in subsequent filtration processes. Secondly, the temperature reduction protects the downstream fan 17 from high-temperature damage, extending its service life. If the fan 17 operates in a high-temperature environment for extended periods, its bearing lubricating oil will deteriorate rapidly, and the motor winding insulation will age faster.

[0034] Lowering the temperature helps improve the adsorption efficiency of activated carbon because physical adsorption is typically exothermic, and lower temperatures favor a shift in the adsorption equilibrium towards adsorption. Simultaneously, larger welding slag particles carried in the welding fume settle on the upstream surface of the activated carbon plate 14 or the inner wall of the exhaust casing 12 under the influence of gravity and inertia as the airflow direction changes and velocity decreases, preventing direct impact on the blades of the fan 17 and causing wear or blockage. This welding slag can be removed during regular maintenance by cleaning the inside of the exhaust casing 12 and replacing or cleaning the activated carbon plate 14.

[0035] The top of the support frame 2 is equipped with a mounting shell 16, which is a hollow box structure. Its bottom is connected to the upper opening of the through groove 15, meaning that the inner cavity of the mounting shell 16 is interconnected with the inner cavity of the exhaust shell 12 through the through groove 15. Three sets of fans 17 are installed inside the mounting shell 16. The three sets of fans 17 can be arranged side-by-side or in a triangular arrangement. The fans 17 are preferably centrifugal or axial fans, with centrifugal fans being more preferred because they have higher air pressure, which can overcome the airflow resistance caused by the activated carbon plate 14 and ensure sufficient suction volume. The three sets of fans 17 can be controlled independently or centrally controlled to operate synchronously. During welding operations, the operator starts the fans 17, and the three sets of fans 17 operate synchronously, generating negative pressure at the suction port of the exhaust shell 12, drawing the fumes generated in the welding area into the exhaust shell 12. The smoke first passes through the activated carbon plate 14, where it is cooled, filtered for solid particles, and adsorbed for gaseous pollutants. The purified air is then discharged from the exhaust port of the mounting shell 16 and directed to the outside of the workshop or to the air circulation system inside the workshop.

[0036] The activated carbon plate 14 is detachably installed inside the exhaust casing 12 using four sets of limiting plates 13. This detachable structure greatly facilitates later maintenance. After prolonged use, the adsorption capacity of the activated carbon plate 14 will gradually become saturated, and the adsorption efficiency will decrease accordingly. At this time, the operator only needs to open the inspection door or side cover of the exhaust casing 12, pull the saturated activated carbon plate 14 out horizontally from the mounting groove between the limiting plates 13, and then insert a new activated carbon plate 14 into the mounting groove to complete the replacement. The entire replacement process does not require disassembly of any pipelines or electrical connections, making the operation simple and quick, which helps to improve the maintenance efficiency and utilization rate of the equipment. At the same time, the pull-out design of the activated carbon plate 14 also facilitates the periodic removal of the activated carbon plate 14 for high-pressure air backflushing cleaning, removing dust and welding slag adhering to its surface, restoring some adsorption performance, and extending the service life of the activated carbon plate 14.

[0037] The usage process of the present invention will be described below with reference to specific embodiments: When using the positioning fixture for pipe welding of the present invention for flanged pipe welding, the ring to be welded is first placed on the upper surface of the base plate 1, directly below the limiting ring 10. The pipe to be welded is then vertically inserted into the inner hole of the ring, so that the flanged end of the pipe contacts the upper surface of the ring to form the welding position. Then, two sets of motors 5 are started. The motors 5 drive the threaded rod 4 to rotate, and the threaded rod 4 drives the connecting plate 6 to move downward along the guide groove 3. The connecting plate 6 drives the limiting ring 10 to descend synchronously. After the bottom surface of the limiting ring 10 contacts the upper surface of the ring, the motors 5 are continued to be driven to further lower the limiting ring 10 by a preset displacement, which corresponds to the required clamping force. For thin-walled rings, the clamping force should be controlled within a small range to avoid indentation. At this time, the clamping force can be precisely controlled by controlling the rotation angle of the motors 5. The magnitude of the clamping force can be indirectly monitored by the drive current of the motors 5. When the drive current reaches a preset threshold, it indicates that the clamping force has reached the set value, and the motors 5 stop running and remain in a self-locking state. At this time, the limiting ring 10 reliably presses the ring onto the base plate 1.

[0038] Next, the two positioning rods 8 are inserted into the positioning holes of the two protrusions 11 at the top of the limiting ring 10 under the preload of the spring 9, thereby achieving a reliable lock between the limiting ring 10 and the connecting plate 6. Due to the elastic clamping effect of the positioning rods 8, even if vibration occurs during the welding process, the positioning rods 8 will not loosen on their own, ensuring that the limiting ring 10 is always in a stable compressed state.

[0039] Start the fan 17 to put the exhaust mechanism into operation. Then, the operator performs argon arc welding or other forms of welding on the joint between the pipe and the ring. The fumes generated during welding are drawn into the exhaust housing 12 by the negative pressure generated by the fan 17, and after being cooled, filtered, and adsorbed by the activated carbon plate 14, they are discharged as clean air. After welding is completed, the operator first turns off the fan 17, then holds the handle at the rear end of the positioning rod 8 and pulls the positioning rod 8 outward so that its front end exits the positioning hole of the protrusion 11, releasing the lock on the limiting ring 10. Lift the limiting ring 10 upward to separate it from the connecting plate 6, and then remove the welded flanged pipe assembly from the base plate 1, thus completing one welding operation cycle.

[0040] Comparative Example 1: Traditional screw-tightening positioning fixtures were used to weld and position flanged tube assemblies of the same specification. This fixture consists of an upper and lower pressure plate. The lower pressure plate is fixed to a base plate, and the upper pressure plate is connected to the lower pressure plate by four M10 hexagonal head bolts. The ring is clamped between the upper and lower pressure plates. The operator uses a torque wrench to tighten the four bolts one by one in a diagonal sequence, setting the torque to 20 N·m. After welding 100 rings consecutively, surface quality inspection revealed that approximately 15% of the thin-walled rings (wall thickness ≤ 2 mm) had visible micro-indentations at the bolt tightening locations, with indentation depths ranging from approximately 0.02 mm to 0.05 mm. Penetrant testing confirmed stress concentration and microcracks at these indentation locations. Furthermore, measurements of the actual tightening torque of the four bolts showed a torque deviation of ±3 N·m between the bolts. In terms of assembly and disassembly efficiency, each clamping and disassembly requires the operator to rotate the bolt about 12 times with a wrench, taking about 45 seconds. After about 500 repeated uses, the bolt shows obvious thread wear, with the thread pitch diameter wear reaching 0.1mm, resulting in unstable locking force and requiring bolt replacement.

[0041] Comparative Example 2: Welding operation tests were conducted on similar positioning fixtures without an exhaust system. Without an exhaust system, the fume concentration around the welding area rapidly increased to 25 mg / m³ within 30 seconds of welding commencement. 3 The above levels far exceed the allowable time-weighted average concentration of welding fumes of 4 mg / m³ specified in the National Occupational Health Standard GBZ 2.1-2019. 3 The limit was reached. Even with dust masks on, operators could still clearly smell the pungent odor, indicating that harmful gaseous components in the welding fumes had not been effectively removed. After two hours of continuous operation, black soot deposits adhered to the tooling surface and surrounding equipment surfaces, making cleaning difficult. However, with the exhaust mechanism of this invention, the fume concentration in the welding area remained consistently at 2 mg / m³ when fan 17 was on. 3 The welding fumes are effectively drawn in and filtered through activated carbon plate 14 before being discharged. After one week of use, a layer of black dust is clearly attached to the surface of activated carbon plate 14, indicating that it has effectively intercepted and adsorbed a large amount of welding slag and fume particles. The filtration performance can be restored simply by regularly removing and cleaning or replacing it, making the operation convenient.

[0042] Comparative Example 3: A positioning fixture design using a single motor-driven, single-sided threaded rod lifting mechanism was tested. This design consists of only one set of motor, threaded rod, and connecting plate. One end of the limiting ring is fixedly connected to the connecting plate, while the other end is suspended or supported by a guide column. During lifting, due to the single-sided driving force, the limiting ring generates a tilting moment, resulting in a significantly lower clamping force on the ring at the other end compared to the driving end, with a clamping force deviation exceeding 30%. When welding thin-walled rings with a wall thickness of 1.5mm, the uneven clamping force causes significant warping deformation under welding thermal stress, with a maximum deformation of 0.3mm, exceeding product tolerance requirements.

[0043] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A positioning fixture for pipe welding, characterized in that, include: Base plate (1); A limiting ring (10) is used to position the ring during the pipe welding process; The positioning mechanism includes a drive assembly and a quick-release assembly. The drive assembly is used to drive the limiting ring (10) to reciprocate in the vertical direction, and the quick-release assembly is used to detachably install the limiting ring (10) onto the drive assembly. And a ventilation system, which is used to draw in and filter the fumes generated during the welding process; The quick-release assembly includes a positioning rod (8) and a spring (9). The spring (9) is sleeved on the outside of the positioning rod (8). The positioning rod (8) is inserted into the protrusion (11) provided on the limiting ring (10) under the elastic preload of the spring (9).

2. The positioning fixture for pipe welding according to claim 1, characterized in that, The drive assembly includes a threaded rod (4) and a connecting plate (6). The connecting plate (6) is threaded onto the outside of the threaded rod (4). When the threaded rod (4) rotates, it drives the connecting plate (6) to move the limiting ring (10) up and down.

3. The positioning fixture for pipe welding according to claim 2, characterized in that, It also includes a support frame (2), which is located at the top of the base plate (1). A guide groove (3) is provided through the support frame (2), and the connecting plate (6) moves through the guide groove (3) and moves along it.

4. The positioning fixture for pipe welding according to claim 3, characterized in that, Motors (5) are provided on both sides of the support frame (2). The bottom end of the threaded rod (4) is connected to the output end of the motor (5) and is driven to rotate by the motor (5).

5. The positioning fixture for pipe welding according to claim 2, characterized in that, The top of the connecting plate (6) is provided with a guide seat (7), the positioning rod (8) is movably disposed inside the guide seat (7), and one end of the spring (9) is connected to the guide seat (7).

6. The positioning fixture for pipe welding according to claim 1, characterized in that, The exhaust mechanism includes an exhaust shell (12), an activated carbon plate (14), and a fan (17). The exhaust shell (12) is located at the bottom of the support frame (2). The fan (17) is connected to the interior of the exhaust shell (12) through a through groove (15). The activated carbon plate (14) is located inside the exhaust shell (12) and is used to filter welding fumes.

7. The positioning fixture for pipe welding according to claim 6, characterized in that, The inner wall of the exhaust shell (12) is provided with a limiting plate (13), and the activated carbon plate (14) is detachably installed between the limiting plates (13).

8. The positioning fixture for pipe welding according to claim 6, characterized in that, The top of the support frame (2) is provided with a mounting shell (16), and the fan (17) is disposed inside the mounting shell (16). The mounting shell (16) is connected to the exhaust shell (12) through the through groove (15).

9. The positioning fixture for pipe welding according to any one of claims 1 to 8, characterized in that, The protrusion (11) at the top of the limiting ring (10) is provided with a hole for the positioning rod (8) to be inserted. The positioning rod (8) is inserted into the hole under the action of the spring (9) to clamp and fix the limiting ring (10).

10. The positioning fixture for pipe welding according to claim 9, characterized in that, The quick-release assembly is configured in two sets, with the two sets of positioning rods (8) inserted into the protrusions (11) of the limiting ring (10) from both sides to form an elastic clamp.

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