A welding device for a steel lined teflon pipe

Abstract

This application discloses a welding device for steel-lined PTFE pipes, relating to the field of welding equipment. It includes a welding robot and a clamping mechanism. The clamping mechanism includes a tubular base with two parallel vertical plates on top. Clamping components and support components are detachably mounted on the vertical plates. The clamping component includes a positioning plate and clamping plates. The bottom of the positioning plate has two pairs of clamping plates that are engaged with the vertical plates. The positioning plate has positioning holes corresponding to the flange bolt holes. The support component includes a support plate and a locking plate. The bottom of the support plate has a locking plate that slides within an L-shaped locking strip. The top of the support plate has a V-shaped opening. This application achieves rapid positioning and locking of the flange through the positioning plate and adaptive support of pipes with different outer diameters through the V-shaped support plate, realizing rapid clamping and positioning of the pipe and flange, significantly reducing operation steps and improving production efficiency.

Description

Technical Field

[0001] This application relates to the field of welding equipment, specifically to a welding apparatus for steel-lined PTFE pipes. Background Technology

[0002] PTFE-lined steel pipes are composite pipes formed by lining the inner wall of carbon steel or stainless steel pipes with a layer of polytetrafluoroethylene (PTFE). They combine the mechanical strength of steel pipes with the excellent corrosion resistance, high-temperature resistance, and low-friction properties of PTFE, and are widely used in corrosive media transportation systems in industries such as chemical, pharmaceutical, petroleum, and metallurgy. During the manufacturing process of PTFE-lined steel pipes, flanges are welded to both ends of the pipe for easy on-site installation and connection.

[0003] Flange welding requires high welding quality. Therefore, the flange end face must be perpendicular to the pipe axis, the flange bolt holes must maintain a certain circumferential positioning accuracy with the pipe axis, and the pipe's plastic lining must not be damaged by overheating during welding. For this reason, precise clamping and positioning of the pipe and flange are necessary before welding to ensure that their relative positional relationship meets design requirements.

[0004] Existing clamping devices typically consist of multiple independent components, such as pipe supports, flange clamps, axial positioning blocks, and circumferential positioning pins. When clamping a welded component, operators need to adjust the position of each component sequentially and tighten multiple locking bolts or handles. This process involves numerous steps, is time-consuming, and severely impacts production efficiency. Summary of the Invention

[0005] In order to overcome the problems existing in the prior art, this application provides a welding device for steel-lined PTFE pipes.

[0006] This application adopts the following technical solution: a welding device for steel-lined PTFE pipes, including a welding mechanism and a clamping mechanism. The welding mechanism is a welding robot, and the clamping mechanism is used to clamp the pipe and flange to be welded. The clamping mechanism includes a tubular base, and the top of the base is provided with two parallel upright plates. The upright plates are detachably provided with clamping components and support components, and at least two of the support components are disposed between a pair of clamping components. The clamping assembly includes a positioning plate and a clamping plate. The bottom of the positioning plate is provided with two pairs of clamping plates. The two pairs of clamping plates are respectively and correspondingly clamped on the two upright plates. The positioning plate is provided with a plurality of positioning holes, which are respectively and correspondingly set with the mounting holes on the flange. The positioning plate and the flange are locked together by bolts. The support assembly includes a support plate and a locking plate. The bottom of the support plate is provided with a pair of locking plates. The pair of locking plates are respectively and correspondingly provided on the outer side of a pair of upright plates. Each of the pair of upright plates is provided with an L-shaped retaining strip on its outer side. The locking plate can slide within the retaining strip. The top of the support plate is provided with a V-shaped opening. The opening can support pipes of different outer diameters.

[0007] Optionally, the top of the base is provided with a through groove that extends axially through the base, and a pair of upright plates are provided at the opening of the through groove. Welding slag can pass between the pair of upright plates and fall into the inner side of the base through the through groove.

[0008] Optionally, each of the upright plates is provided with a clamping piece on both sides. The bottom of the clamping piece facing the upright plate has an arc-shaped guide surface. Each clamping piece has a through hole at the upper part of the end away from the positioning piece. The two clamping pieces at the bottom of each positioning piece can be locked together by bolts, and the bolts are inserted into the two through holes. The top of the positioning piece is provided with a slot that extends downward in a vertical direction. The radial interface of the slot is convex. The head of the bolt is fitted into the slot from top to bottom, and the shank of the bolt is located on the outside of the slot.

[0009] Optionally, the horizontal end of the locking strip is connected to the outer wall of the upright plate, the vertical end of the locking strip is parallel to and separate from the upright plate, and the locking piece is inserted between the vertical end of the locking strip and the upright plate; The horizontal end of the locking strip is provided with a plurality of adjustment holes, which are spaced apart along the length of the locking strip. The adjustment holes are threaded holes, and an adjustment screw is provided in the adjustment hole located below the locking plate. The adjustment screw can push the locking plate to move back and forth along the height of the locking plate.

[0010] Optionally, the base is disposed on a base plate, and the base plate is further provided with a horizontal sliding groove. A slide seat driven by a horizontal motor is disposed in the horizontal sliding groove. A vertical sliding groove is disposed on the side of the slide seat facing the base. A storage rack plate driven by a vertical motor is disposed in the vertical sliding groove. The storage rack plate is used to store positioning pieces of different sizes.

[0011] Optionally, the horizontal motor is used to drive the storage rack plate and the plurality of positioning plates to move along the length direction of the base, and the vertical motor is used to drive the storage rack plate and the plurality of positioning plates to move along the height direction of the base.

[0012] Optionally, the bottom of the storage rack is provided with a plurality of receiving slots, which are spaced apart along a straight line parallel to the axial direction of the base. The top of the storage rack is provided with a plurality of upper release holes, and the plurality of upper release holes correspond one-to-one with the plurality of receiving slots. The upper release holes are connected to the receiving slots, and a release screw is adaptedly screwed into the upper release holes. Below each of the receiving slots are a pair of positioning plates of the same size. Each pair of positioning plates has an L-shaped connecting rod at its top. The vertical end of the connecting rod is connected to the top of the positioning plate, and the horizontal end of the connecting rod extends into the receiving slot. The release screw passes through the horizontal ends of the two connecting rods in sequence, and the release screw is threadedly connected to the horizontal ends of the connecting rods.

[0013] Optionally, a pair of positioning pieces under the same receiving groove are coaxially arranged, and several positioning pieces under different receiving grooves have the same bottom height.

[0014] Optionally, the lengths of the pair of connecting rods below the same receiving groove are different, and the horizontal ends of the pair of connecting rods are stacked one on top of the other in the corresponding receiving groove. Each of the connecting rods has a lower release hole at its horizontal end. One upper release hole and two lower release holes corresponding to the same receiving groove are coaxially arranged. Both the upper release hole and the lower release hole are threaded holes. The release screw is adapted to be screwed into the upper release hole and the lower release hole.

[0015] Optionally, when the release screw rotates upward, the corresponding pair of positioning plates are released downward in sequence; After both of the positioning plates are released, the release screw remains screwed into the upper release hole.

[0016] Compared with the prior art, this application has the following advantages: 1. The clamping assembly is directly aligned with the flange mounting holes through the positioning holes on the positioning plate and locked with bolts. At the same time, the two pairs of clamping plates at the bottom of the positioning plate are locked onto the vertical plate to achieve quick positioning. There is no need to adjust multiple independent clamping components one by one, which reduces the clamping operation steps and significantly shortens the auxiliary time.

[0017] 2. The support assembly uses a V-shaped opening support plate, which can adaptively support pipes of different outer diameters without the need to replace support seats of different specifications; the locking plate slides in the locking strip and can be pushed by the adjusting screw to achieve precise adjustment of the support height, ensuring that the axis of pipes of different diameters is aligned with the center of the flange.

[0018] 3. The storage rack, driven by horizontal and vertical chutes, can automatically deliver positioning plates of different sizes to the corresponding workstations in sequence. When the release screw rotates, a pair of positioning plates are released in sequence, realizing the rapid and automatic replacement of positioning plates. This adapts to various production scenarios where the flanges at both ends of the same pipeline are of the same or different models, further reducing manual intervention. Attached Figure Description

[0019] Figure 1 This is an illustrative three-dimensional representation of the present application. Figure 1 ; Figure 2 This is an illustrative three-dimensional representation of the present application. Figure 2 ; Figure 3 This is a reference diagram showing the assembly status of the clamping mechanism with pipes and flanges; Figure 4 This is a reference diagram showing the assembly state of the base and clamping components; Figure 5 This is a reference diagram showing the assembly state of the base and support components; Figure 6 It is a schematic 3D diagram of the storage rack and base; Figure 7 This is a reference diagram showing the assembly state of the storage rack and clamping components; Figure 8 It is a schematic 3D view of a pair of positioning plates of the same size; In the diagram: 1. Clamping mechanism; 11. Base; 110. Through slot; 12. Vertical plate; 13. Clamping assembly; 131. Positioning piece; 1311. Positioning hole; 1312. Slot; 132. Clamping piece; 1321. Guide surface; 1322. Through hole; 133. Bolt; 134. Connecting rod; 1340. Lower release hole; 14. Support assembly; 141. Support piece; 1410. Opening; 142. Locking piece; 143. Locking strip; 1430. Adjustment hole; 144. Adjustment screw; 15. Base plate; 151. Horizontal slide; 152. Horizontal motor; 16. Slide; 161. Vertical slide; 162. Vertical motor; 17. Storage rack; 171. Receiving slot; 172. Upper release hole; 173. Release screw; 2. Pipe; 3. Flange. Detailed Implementation

[0020] The present application will now be further described in conjunction with the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0021] like Figure 1-8As shown, this embodiment provides a welding device for steel-lined PTFE pipes, including a welding mechanism and a clamping mechanism 1. The welding mechanism is a welding robot, and the clamping mechanism 1 is used to clamp the pipe 2 and flange 3 to be welded. The clamping mechanism 1 includes a tubular base 11, and two parallel upright plates 12 are provided on the top of the base 11. Clamping components 13 and support components 14 are detachably provided on the upright plates 12. At least two support components 14 are disposed between a pair of clamping components 13. The support components 14 are used to support the pipe 2, and the clamping components 13 are used to fix the flange 3.

[0022] The clamping assembly 13 includes a positioning piece 131 and clamping pieces 132. The bottom of the positioning piece 131 has two pairs of clamping pieces 132, which are respectively and correspondingly engaged on the two upright plates 12. That is, two clamping pieces 132 in each pair are located on opposite sides of the upright plate 12, clamping the upright plate 12 in the middle. The positioning piece 131 has several positioning holes 1311, which correspond one-to-one with the mounting holes on the flange 3. The positioning piece 131 and the flange 3 are locked together by bolts 133, fixing the flange 3 and the positioning piece 131 as a single unit.

[0023] The support assembly 14 includes a support plate 141 and a locking plate 142. A pair of locking plates 142 are located at the bottom of the support plate 141, and are respectively and correspondingly positioned on the outer sides of a pair of upright plates 12. Each of the upright plates 12 has an L-shaped retaining strip 143 on its outer side, allowing the locking plate 142 to slide vertically within the retaining strip 143. The top of the support plate 141 has a V-shaped opening 1410, which can support pipes 2 of different outer diameters; the pipe 2 automatically centers after being inserted into the V-shaped opening 1410.

[0024] During the clamping operation, the operator first places two positioning plates 131 according to the length of pipe 2 and the overall welding position. Then, the flange 3 to be welded is aligned with the positioning plates 131, and bolts 133 are passed through the positioning holes 1311 and the flange 3 mounting holes to lock them together. Next, at least two support plates 141 are evenly placed between the two positioning plates 131, and pipe 2 is placed into the V-shaped opening 1410 of the support plate 141. The height of the support plate 141 is adjusted so that the axis of pipe 2 is aligned with the center of flange 3. Finally, the welding robot welds the joint between flange 3 and pipe 2.

[0025] The base 11 has a through groove 110 at its top, which extends axially through the base 11. A pair of upright plates 12 are located at the opening of the through groove 110. Welding slag generated during welding can pass between the pair of upright plates 12 and fall into the inner side of the base 11 through the through groove 110, preventing slag from accumulating in the welding area and affecting the welding quality or subsequent clamping operations. It also facilitates the collection and cleaning of welding slag.

[0026] Each upright plate 12 has a clamping piece 132 on both sides, meaning that two clamping pieces 132 in each pair are located on the left and right sides of the upright plate 12, respectively. The bottom of the clamping piece 132 facing the upright plate 12 has an arc-shaped guide surface 1321 to facilitate a smooth transition when the clamping piece 132 is inserted into the upright plate 12 from top to bottom. Each clamping piece 132 has a through hole 1322 at the upper part of the end away from the positioning piece 131. The two clamping pieces 132 at the bottom of each positioning piece 131 can be locked together by bolts 133, which pass through the two through holes 1322. After tightening the bolts 133, the two clamping pieces 132 clamp the upright plate 12, fixing the positioning piece 131 to the upright plate 12.

[0027] The positioning piece 131 has a slot 1312 on its top, which extends vertically downwards and has a convex cross-section. The head of the bolt 133 is fitted into the slot 1312 from top to bottom, while the shank of the bolt 133 is located outside the slot 1312. This allows the bolt 133, which connects the positioning piece 131 to the flange 3, to be placed conveniently in the slot 1312 after disassembly, preventing it from falling out and facilitating quick removal and placement of the bolt 133.

[0028] The horizontal end of the locking strip 143 is connected to the outer wall of the vertical plate 12, and the vertical end of the locking strip 143 is parallel to and separate from the vertical plate 12. The locking piece 142 is inserted between the vertical end of the locking strip 143 and the vertical plate 12. The horizontal end of the locking strip 143 is provided with several adjustment holes 1430, which are spaced apart along the length of the locking strip 143. The adjustment holes 1430 are threaded holes, and an adjustment screw 144 is provided in the adjustment hole 1430 located below the locking piece 142. The adjustment screw 144 can push the locking piece 142 to move back and forth along the height direction of the locking piece 142.

[0029] When the height of the support plate 141 needs to be adjusted, the operator rotates the adjusting screw 144 upwards. The adjusting screw 144 pushes the locking plate 142 upwards, and the locking plate 142 drives the support plate 141 to rise synchronously. When the adjusting screw 144 is rotated downwards, the locking plate 142 and the support plate 141 descend under the action of gravity. The adjusting holes 1430 at different positions can accommodate pipes 2 of different lengths, ensuring that the height of the support plate 141 can be reliably adjusted by rotating the adjusting screw 144.

[0030] A base 11 is mounted on a base plate 15. The base plate 15 also has a horizontal slide groove 151. A slide block 16, driven by a horizontal motor 152, is located within the horizontal slide groove 151. A vertical slide groove 161, driven by a vertical motor 162, is located on the side of the slide block 16 facing the base 11. A storage rack 17, driven by a vertical motor 162, is located within the vertical slide groove 161. The storage rack 17 is used to store positioning pieces 131 of different sizes. The horizontal motor 152 drives the storage rack 17 and several positioning pieces 131 to move along the length of the base 11, while the vertical motor 162 drives the storage rack 17 and several positioning pieces 131 to move along the height of the base 11. Through movement in both directions, the storage rack 17 can deliver positioning pieces 131 of a specified size to the designated retrieval station for assembly by the operator.

[0031] The storage rack 17 has several receiving slots 171 at its bottom, spaced apart along a straight line parallel to the axial direction of the base 11. Each receiving slot 171 is used to store a pair of positioning pieces 131 of the same size (used for the left and right ends of the pipe 2, respectively). The top of the storage rack 17 has several upper release holes 172, each corresponding to a receiving slot 171 and communicating with the receiving slot 171. A release screw 173 is fitted into each upper release hole 172. Below each receiving slot 171 is a pair of positioning pieces 131 of the same size. Each pair of positioning pieces 131 has an L-shaped connecting rod 134 at its top, with the vertical end of the connecting rod 134 connected to the top of the positioning piece 131 and the horizontal end of the connecting rod 134 extending into the receiving slot 171. The release screw 173 passes through the horizontal ends of the two connecting rods 134 in sequence, and the release screw 173 is connected to the horizontal ends of the connecting rods 134 by threads.

[0032] When the release screw 173 rotates upward, it first disengages from the horizontal end of the lower connecting rod 134 (unscrewed connection). At this time, a corresponding positioning piece 131 automatically falls and locks between the pair of upright plates 12. Continuing to rotate upward, the release screw 173 disengages from the horizontal end of the upper connecting rod 134 (unscrewed connection), releasing the second positioning piece 131. Thus, by controlling the number of rotations of the release screw 173, a pair of positioning pieces 131 can be released sequentially, facilitating quick assembly of the positioning pieces 131 by the operator.

[0033] A pair of positioning pieces 131 under the same receiving slot 171 are coaxially arranged (i.e., the central axes of the two positioning pieces 131 coincide). The bottom heights of several positioning pieces 131 under different receiving slots 171 are the same, that is, the top heights of all positioning pieces 131 are the same. This ensures that the height difference between all positioning pieces 131 and the upright plate 12 is consistent, avoiding the instability of the automatic lowering action of the positioning pieces 131 due to excessive height difference or the need to adjust the height of the storage rack 17 multiple times, thus improving the smoothness of automated retrieval and placement.

[0034] A pair of connecting rods 134 below the same receiving groove 171 have different lengths, causing the horizontal ends of the pair of connecting rods 134 to stack vertically within the corresponding receiving groove 171. Each connecting rod 134 has a lower release hole 1340 at its horizontal end, and one upper release hole 172 and two lower release holes 1340 corresponding to the same receiving groove 171 are coaxially arranged. Both the upper release hole 172 and the lower release holes 1340 are threaded holes, and the release screw 173 is adapted to be screwed into the upper release hole 172 and the lower release hole 1340. When the release screw 173 is rotated upward, the corresponding pair of positioning plates 131 are released downward in sequence. Specifically, after the release screw 173 releases the first positioning piece 131, the second positioning piece 131 in the receiving groove 171 remains locked. At this time, according to the length of the pipe 2 and the welding allowance, the sliding seat moves horizontally a predetermined distance to transport the second positioning piece 131 to the appropriate position. Then, by rotating the release screw 173, the second positioning piece 131 will be released, improving the release accuracy of the two positioning pieces 131 and reducing the difficulty of subsequent adjustments by the operator. After both positioning pieces 131 are released, the release screw 173 remains screwed into the upper release hole 172 to prevent the release screw 173 from being lost.

[0035] This embodiment also provides a clamping method for a steel-lined PTFE pipe welding device, including the following steps: Step 1: According to the dimensions of the flange 3 to be welded, move the storage rack 17 to the first release position and rotate the release screw 173 to release the first positioning piece 131 that matches the flange 3 onto the upright plate 12. Then, according to the length of the pipe 2 and the welding allowance requirements, move the storage rack 17 to the second release position and rotate the release screw 173 to release the second positioning piece 131 that matches the flange 3 onto the upright plate 12. Step 2: Remove bolt 133 from slot 1312 of positioning piece 131 and pass bolt 133 through through holes 1322 of two clamping pieces 132 to lock positioning piece 131 to upright plate 12. Then align flange 3 with positioning piece 131, remove bolt 133 and pass bolt 133 through positioning hole 1311 and flange 3 mounting hole to lock flange 3 to positioning piece 131. Step 3: Based on the distance between the two positioning plates 131, place at least two support plates 141 evenly between the two positioning plates 131, then put the pipe 2 into the V-shaped opening 1410 of the support plate 141, and rotate the adjusting screw 144 up or down to adjust the height of the support plate 141 so that the axis of the pipe 2 is aligned with the center of the flange 3. Step 4: Start the welding robot to weld the joint between flange 3 and pipe 2. Done.

[0036] The above embodiments are merely preferred embodiments of this application and should not be construed as limiting the scope of protection of this application. Any non-substantial changes and substitutions made by those skilled in the art based on this application shall fall within the scope of protection claimed by this application.

Claims

1. A welding device for steel-lined PTFE pipes, comprising a welding mechanism and a clamping mechanism (1), wherein the welding mechanism is a welding robot, and the clamping mechanism (1) is used to clamp the pipe (2) and flange (3) to be welded, characterized in that, The clamping mechanism (1) includes a tubular base (11), and the top of the base (11) is provided with two parallel upright plates (12). The upright plates (12) are detachably provided with clamping components (13) and support components (14), and at least two of the support components (14) are provided between a pair of clamping components (13). The clamping assembly (13) includes a positioning piece (131) and a clamping piece (132). The bottom of the positioning piece (131) is provided with two pairs of clamping pieces (132). The two pairs of clamping pieces (132) are respectively and correspondingly clamped on the two upright plates (12). The positioning piece (131) is provided with a plurality of positioning holes (1311). The plurality of positioning holes (1311) are respectively and correspondingly set with the mounting holes on the flange (3). The positioning piece (131) and the flange (3) are locked together by bolts (133). The support assembly (14) includes a support piece (141) and a locking piece (142). The bottom of the support piece (141) is provided with a pair of locking pieces (142). The pair of locking pieces (142) are respectively and correspondingly provided on the outer side of the pair of upright plates (12). The outer side of each pair of upright plates (12) is provided with an L-shaped retaining strip (143). The locking piece (142) can slide in the retaining strip (143). The top of the support piece (141) is provided with a V-shaped opening (1410). The opening (1410) can support pipes (2) of different outer diameters.

2. The welding apparatus for steel-lined PTFE pipes according to claim 1, characterized in that, The top of the base (11) is provided with a through groove (110), which passes through the base (11) axially. A pair of upright plates (12) are provided at the opening of the through groove (110). Welding slag can pass between the pair of upright plates (12) and fall into the inner side of the base (11) through the through groove (110).

3. The welding apparatus for steel-lined PTFE pipes according to claim 2, characterized in that, Each of the upright plates (12) has a clamping piece (132) on both sides. The clamping piece (132) has an arc-shaped guide surface (1321) at the bottom of the side facing the upright plate (12). Each clamping piece (132) has a through hole (1322) at the upper part of the end away from the positioning piece (131). The two clamping pieces (132) at the bottom of each positioning piece (131) can be locked together by bolts (133), and the bolts (133) are inserted into the two through holes (1322). The top of the positioning piece (131) is provided with a slot (1312), the slot (1312) extends downward in the vertical direction, the radial interface of the slot (1312) is convex, the head of the bolt (133) is adapted to be inserted into the slot (1312) from top to bottom, and the shank of the bolt (133) is located on the outside of the slot (1312).

4. The welding apparatus for steel-lined PTFE pipes according to claim 2, characterized in that, The horizontal end of the locking strip (143) is connected to the outer wall of the upright plate (12), the vertical end of the locking strip (143) is parallel to the upright plate (12) and separated from each other, and the locking piece (142) is inserted between the vertical end of the locking strip (143) and the upright plate (12). The horizontal end of the locking strip (143) is provided with a plurality of adjustment holes (1430), and the plurality of adjustment holes (1430) are spaced apart along the length direction of the locking strip (143). The adjustment holes (1430) are threaded holes. An adjustment screw (144) is provided in the adjustment hole (1430) located below the locking piece (142). The adjustment screw (144) can push the locking piece (142) to move back and forth along the height direction of the locking piece (142).

5. A welding apparatus for steel-lined PTFE pipes according to any one of claims 1-4, characterized in that, The base (11) is mounted on the base plate (15), and the base plate (15) is also provided with a horizontal slide groove (151). The horizontal slide groove (151) is provided with a slide seat (16) driven by a horizontal motor (152). The slide seat (16) is provided with a vertical slide groove (161) on the side facing the base (11). The vertical slide groove (161) is provided with a storage rack plate (17) driven by a vertical motor (162). The storage rack plate (17) is used to store positioning pieces (131) of different sizes.

6. The welding apparatus for steel-lined PTFE pipes according to claim 5, characterized in that, The horizontal motor (152) is used to drive the storage rack plate (17) and the plurality of positioning pieces (131) to move along the length direction of the base (11), and the vertical motor (162) is used to drive the storage rack plate (17) and the plurality of positioning pieces (131) to move along the height direction of the base (11).

7. The welding apparatus for steel-lined PTFE pipes according to claim 5, characterized in that, The bottom of the storage rack (17) is provided with a plurality of receiving slots (171), and the plurality of receiving slots (171) are spaced apart along a straight line, which is parallel to the axial direction of the base (11). The top of the storage rack plate (17) is provided with a plurality of upper release holes (172), and the plurality of upper release holes (172) correspond one-to-one with the plurality of receiving slots (171). The upper release holes (172) are connected to the receiving slots (171), and a release screw (173) is adaptedly screwed into the upper release hole (172). Below each of the receiving slots (171) is a pair of positioning pieces (131) of the same size. Each pair of positioning pieces (131) has an L-shaped connecting rod (134) at its top. The vertical end of the connecting rod (134) is connected to the top of the positioning piece (131), and the horizontal end of the connecting rod (134) extends into the receiving slot (171). The release screw (173) passes through the horizontal ends of the two connecting rods (134) in sequence, and the release screw (173) is threadedly connected to the horizontal end of the connecting rod (134).

8. The welding apparatus for steel-lined PTFE pipes according to claim 7, characterized in that, A pair of positioning pieces (131) under the same receiving groove (171) are coaxially arranged, and the bottom heights of several positioning pieces (131) under different receiving grooves (171) are the same.

9. The welding apparatus for steel-lined PTFE pipes according to claim 7, characterized in that, The lengths of the pair of connecting rods (134) below the same receiving groove (171) are different, and the horizontal ends of the pair of connecting rods (134) are stacked one on top of the other in the corresponding receiving groove (171); Each of the connecting rods (134) has a lower release hole (1340) at its horizontal end. One upper release hole (172) and two lower release holes (1340) corresponding to the same receiving groove (171) are coaxially arranged. The upper release hole (172) and the lower release holes (1340) are both threaded holes. The release screw (173) is adapted to be screwed into the upper release hole (172) and the lower release hole (1340).

10. A welding apparatus for steel-lined PTFE pipes according to claim 9, characterized in that, When the release screw (173) rotates upward, the corresponding pair of positioning plates (131) are released downward in sequence; After both of the positioning plates (131) are released, the release screw (173) remains screwed into the upper release hole (172).

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