A superheater tube bundle assembly elbow welding device

Abstract

The present invention belongs to the field of pipe welding, and in particular relates to a superheater tube bundle assembly elbow welding device. It comprises a welding gun housing, wherein a welding mechanism is provided inside the welding gun housing, and both sides of the welding mechanism are provided with a tightening mechanism for pressing the pipe to be welded inwardly toward the weld position and a limiting mechanism for applying a pre-tightening force to the pipe in the direction of the weld; the tightening mechanism is located on the outside of the limiting mechanism; the present invention expands the molten pool width of the traditional straight weld through the dynamic compensation mechanism, significantly increases the cross-sectional area of ​​the weld, and solves the problem of insufficient welding strength caused by uneven gaps; at the same time, the inclined push rod of the limiting mechanism uses an axial component force to pre-tighten the pipe, and the push spring of the tightening mechanism further pushes the pipe to be precisely centered; the two work together to greatly reduce the butt gap of the pipe, ensure the uniformity of the molten pool when the parent material is self-melted, avoid incomplete welding or porosity defects, and at the same time, the tighter fit further improves the welding quality.

Description

Technical Field

[0001] The invention belongs to the field of pipe welding, and in particular relates to a pipe bending welding device for a superheater tube bundle assembly. Background Art

[0002] The superheater tube bundle assembly is a key component in the boiler superheater. There are four types of superheater tube bundles: convection type, screen type, wall type and wall-wrapped type. The convection superheater tube bundle assembly is the most commonly used, mostly using a serpentine tube type. It is arranged in the flue with a flue gas temperature of 450-1000℃. Affected by the horizontal and vertical scouring of the flue gas, it mainly absorbs the heat of the flue gas by convection, and also absorbs some heat by radiation. Among the superheater tube bundle assemblies, some tube bundles are processed by tube bending machines, and some are welded by a combination of straight tubes and bent tubes using a tube-to-tube automatic welding machine.

[0003] When welding two pipes, current automatic pipe welding machines primarily align and lock the two pipes inside the machine. A non-consumable tungsten electrode, acting as an electrode, generates a high-temperature arc (up to 3000°C) between the electrode and the pipe at the weld seam, melting the base metal at the weld seam to form a molten pool. This creates the weld seam through self-melting of the base metal. Prior to welding, the two pipes are manually aligned, leaving an uncontrollable gap between them. The size of this gap affects the weld strength. Generally, the closer the two pipes fit, the smaller the gap, resulting in a stronger weld after the high-temperature self-melting of the electrode and the base metal. However, if the gap is larger, while the weld seam can be completed after the high-temperature self-melting of the electrode and the base metal, the weld strength is significantly reduced for the same weld seam width due to the presence of a finite melting zone between the electrode and the base metal.

[0004] Therefore, in order to comprehensively improve the welding quality between two pipes when using a pipe-to-pipe automatic welding machine, the present invention provides a pipe bending welding device for a superheater tube bundle assembly. Summary of the Invention

[0005] In order to solve the above problems, the present invention provides a superheater tube bundle assembly elbow welding device, which is used to solve the problems mentioned in the above background technology.

[0006] In order to achieve the above-mentioned objectives, the embodiments of the present application provide the following technical solutions: The present invention provides a superheater tube bundle assembly elbow welding device, comprising a welding gun housing, wherein a welding mechanism is provided inside the welding gun housing, and both sides of the welding mechanism are provided with a tightening mechanism for pressing the pipe to be welded inward toward the weld position and a limiting mechanism for applying a pre-tightening force to the pipe in the direction of the weld; the tightening mechanism is located on the outside of the limiting mechanism.

[0007] The welding gun housing includes a hand-held section and a clamping section. The clamping section is provided with a welding cavity. The clamping section above the welding cavity is hingedly provided with two semi-arc pressure handles with the same radius and different widths. The two semi-arc pressure handles are locked to the clamping section by two snap locks respectively.

[0008] An annular slide rail is provided inside the welding chamber, and the welding mechanism includes an electromagnetic slide seat provided inside the slide rail. An electrode is provided inside the electromagnetic slide seat, which generates a high-temperature arc between the electrode and the pipe to be welded and melts the pipe to be welded to form a molten pool; the electrode is mounted on the electromagnetic slide seat through a fixed platform, and a plurality of arc blocks are alternately provided on both sides of the slide rail; lugs are provided on both sides of the fixed platform, which alternately contact the arc blocks and enable the electrode to move back and forth laterally during welding to widen the weld.

[0009] The tightening mechanism includes an outer fixing ring and an inner fixing ring arranged symmetrically, and the inner circumferential surface of the inner fixing ring is evenly provided with sliding grooves, and a pushing seat that moves along the axial direction of the inner fixing ring is provided in the sliding groove, and a close-fitting module that slides radially along the inner fixing ring and presses against the pipe to be welded is provided inside the pushing seat.

[0010] According to a favorable embodiment, each of the snap locks includes a fixed semi-arc pressure handle and a clamping seat fixed on two corresponding positions on the clamping section, a lock groove is provided on the clamping seat fixed on the semi-arc pressure handle, and a locking claw is installed on the clamping seat fixed on the clamping section; a connecting block is provided on the clamping seat through a reset spring, and the connecting block can slide inside the clamping seat; the locking claw cooperates with the connecting block.

[0011] According to a favorable embodiment, an installation groove is provided at a position corresponding to the slide groove on the side wall of the outer fixed ring, and a support is fixedly arranged in the installation groove, and a compressed push spring is connected between the support and the push seat; the push seats inside each semi-arc inner ring are commonly connected to a steel wire rope, and the other end of the steel wire rope passes through the wire holes on the support at the corresponding position and the corresponding semi-arc outer ring in sequence, and finally passes through the connecting block inside the corresponding snap lock, and a wire hole is provided at the center position of the support; the spring coefficient of the reset spring is much larger than the spring coefficient of the push spring.

[0012] According to a favorable embodiment, the close-fitting module includes a pressure block that is slidably arranged inside the push seat through a spring, and the end of the pressure block away from the spring is Y-shaped. The outer wall of the pressure block is provided with a clamping sleeve to limit the inside of the push seat; the Y-shaped section of the pressure block protrudes from the outer wall of the push seat.

[0013] According to a favorable embodiment, each of the outer fixing rings is composed of two semi-arc outer rings, one of which is installed on the semi-arc pressure handle and the other is installed on the clamping section; each of the inner fixing rings is composed of two semi-arc inner rings, and the two semi-arc inner rings are respectively installed on the corresponding semi-arc outer rings.

[0014] According to a favorable embodiment, two guide rods are provided inside the electromagnetic slide, and a fixed platform is provided between the two guide rods for sliding together. The fixed platform is located in the middle of the two guide rods, and springs are provided on both sides of the guide rods to automatically reset the electrode when the lug contacts the arc block.

[0015] According to a favorable embodiment, the limiting mechanism includes two groups of push rods circumferentially arranged on the inner wall of the welding chamber, and both groups of push rods are inclined toward the welding mechanism, each group of push rods includes a fixed cylinder evenly arranged on the inner wall of the welding chamber by a threaded manner, and the interior of the fixed cylinder is connected to a telescopic rod by a spring sliding connection, and the end of the telescopic rod facing the axis of the welding chamber is provided with a ball that contacts the outer wall of the pipe to be welded; the push rod is in rolling contact with the outer wall of the pipe through the ball, and applies a pre-tightening force to the pipe in the direction of the weld when the semi-arc pressure handle is buckled.

[0016] According to an advantageous embodiment, the hand-held portion of the welding gun housing is provided with a control button for controlling the power supply and movement of the electromagnetic slide and the electrode.

[0017] According to an advantageous embodiment, a perspective hole is provided on the wider semi-arc-shaped pressing handle, and a perspective glass is embedded in the perspective hole for observing the welding status inside the welding cavity.

[0018] According to an advantageous embodiment, one end of the pressing block located inside the pushing seat is provided with a ball that rolls and rubs against the pushing seat.

[0019] Compared with the prior art, the embodiment of the present invention provides a superheater tube bundle assembly elbow welding device with the following beneficial effects: 1. The present invention drives the electrode through an electromagnetic slide to combine with the arc block and the lug to automatically perform a transverse serpentine movement during the annular welding process. Through this dynamic compensation mechanism, the molten pool width of the traditional straight weld is expanded, and the cross-sectional area of ​​the weld is significantly increased, thereby solving the problem of insufficient welding strength caused by uneven gaps.

[0020] 2. The inclined push rod of the limiting mechanism in the present invention pre-tightens the pipe fitting through the axial component force, while the push spring of the tightening mechanism further pushes the pipe fitting to be precisely centered; the two work together to greatly reduce the butt gap of the pipe fittings, ensure the uniformity of the molten pool during self-melting of the parent material, avoid incomplete welding or porosity defects, and at the same time, the tighter fit further improves the welding quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a three-dimensional structural diagram of the present invention in the welded pipe fitting state.

[0022] Figure 2 It is a three-dimensional structural diagram of the present invention.

[0023] Figure 3 It is the front view of the present invention.

[0024] Figure 4 For the present invention Figure 3 Partial cross-sectional view of the middle structure.

[0025] Figure 5 It is a partial cross-sectional view of the structure of the side view of the present invention.

[0026] Figure 6 This invention Figure 4 A magnified view of the local structure at point A.

[0027] Figure 7 This invention Figure 5 Enlarged view of the local structure at point B in the middle.

[0028] Figure 8 It is a schematic diagram of the internal structure of the electromagnetic slide of the present invention.

[0029] Reference numerals in the figure: 1, welding gun housing; 2, welding mechanism; 3, pressing mechanism; 4, limiting mechanism; 11, hand-held section; 12, clamping section; 13, welding chamber; 14, semi-arc pressure handle; 15, snap lock; 16, perspective hole; 131, slide rail; 132, electromagnetic slide; 133, electrode; 141, guide rod; 142, fixing table; 143, lug; 144, arc block; 31, outer fixing ring; 311, semi-arc outer ring ; 32. Inner fixed ring; 321. Semi-arc inner ring; 322. Slide groove; 323. Push seat; 312. Mounting groove; 313. Support; 314. Wire hole; 315. Push spring; 324. Close contact module; 151. Card seat; 152. Locking groove; 153. Locking claw; 154. Return spring; 155. Connecting block; 156. Wire rope; 325. Pressing block; 41. Push rod; 42. Fixed cylinder; 43. Telescopic rod. DETAILED DESCRIPTION

[0030] The following is combined with Figure 1 -Attached Figure 8 This application is described in further detail.

[0031] Please refer to Figure 1 、 Figure 2 and Figure 7 A superheater tube bundle assembly elbow welding device includes a welding gun housing 1, a welding mechanism 2, a tightening mechanism 3 and a limiting mechanism 4; the welding gun housing 1 is provided with a welding mechanism 2 for circumferentially girth welding the pipe fitting, and both sides of the welding mechanism 2 are provided with a tightening mechanism 3 for pressing the pipe fitting to be welded inward toward the weld position and a limiting mechanism 4 for limiting the pipe fitting to maintain stability; the tightening mechanism 3 is located on the outside of the limiting mechanism 4.

[0032] Specifically, when welding two pipe fittings, the bent pipe and the straight pipe can be fixed inside the welding gun housing 1 by the tightening mechanism 3 and the limiting mechanism 4 respectively. At the same time, when the tightening mechanism 3 and the limiting mechanism 4 are fixed together, the two pipe fittings to be welded can be pushed closer to each other, thereby reducing the weld gap between the two pipe fittings, so that the welding effect can be guaranteed when welding is performed by the welding mechanism 2. At the same time, in order to further improve the welding effect, when the welding mechanism 2 moves circumferentially along the weld position of the pipe fitting, a serpentine movement method is adopted to further increase the weld width.

[0033] See Figure 2 The welding gun housing 1 includes a hand-held section 11 and a clamping section 12. A control button is provided on the hand-held section 11, and a welding chamber 13 is provided on the clamping section 12. Two semi-arc pressure handles 14 with the same radius and different widths are hingedly provided on the clamping section 12 above the welding chamber 13. The two semi-arc pressure handles 14 are connected to the clamping section 12 by two snap locks 15 respectively; one of the semi-arc pressure handles 14 with a wider width is provided with a perspective hole 16 for observing the internal condition of the welding chamber 13, and a perspective glass is provided in the perspective hole 16.

[0034] When it is necessary to weld the pipe fittings, open the snap locks 15 in sequence, lift up the two semi-arc pressure handles 14, first place the welding port of one of the pipe fittings to be welded at the position corresponding to the welding mechanism 2, then press down the semi-arc pressure handle 14 and lock it with the snap lock 15, then place the other pipe fitting in the opposite position, and keep the end of the pipe fitting aligned with the previous pipe end, finally press down the semi-arc pressure handle 14 and lock it with the snap lock 15, and then you can proceed with the subsequent welding operation.

[0035] See Figure 5 and Figure 7 The limiting mechanism 4 includes two groups of push rods 41 circumferentially arranged on the inner wall of the welding cavity 13, and the two groups of push rods 41 are inclined toward the welding mechanism 2. Each group of push rods 41 includes a fixed cylinder 42 evenly arranged on the inner wall of the welding cavity 13 by a threaded manner. The interior of the fixed cylinder 42 is connected to a telescopic rod 43 through a spring sliding connection. The end of the telescopic rod 43 facing the axis of the welding cavity 13 is provided with a ball that contacts the outer wall of the pipe to be welded; the provided ball can reduce the friction between the telescopic rod 43 and the outer wall of the pipe, which is conducive to relative sliding between the pipe and the telescopic rod 43.

[0036] When the pipe to be welded is placed inside the welding cavity 13 and the upper semi-arc-shaped pressure handle 14 is buckled, the outer wall of the pipe will conflict with the push rod 41, and the telescopic rod 43 will be partially compressed and retracted into the interior of the fixing cylinder 42. Since the push rods 41 on both sides are inclined toward the welding mechanism 2, after the pipe is fixed, the two groups of push rods 41 on both sides will respectively generate accumulated pressure on the pipe on each side to move closer to the welding mechanism 2. At this time, the weld positions of the two pipes to be welded will be closer, thereby effectively improving the welding quality.

[0037] See Figure 2 The welding chamber 13 is provided with an annular slide rail 131. The welding mechanism 2 includes an electromagnetic slide 132 disposed within the slide rail 131. An electrode 133 is disposed within the electromagnetic slide 132 for generating a high-temperature arc with the pipe to be welded and melting the pipe to be welded to form a molten pool. In this embodiment, the electrode 133 is a non-consumable tungsten electrode. During normal welding, the electromagnetic slide 132 and the electrode 133 are energized by operating a button. After the electromagnetic slide 132 is energized, it moves along the slide rail 131. When the electrode 133 is energized, a high-temperature arc (up to 3000°C or above) is generated at the weld position between the pipes, melting the pipe at the weld position to form a molten pool. The weld is formed by self-melting the pipe, and the interface position of the two pipes is welded together.

[0038] In order to increase the width of the weld and improve the firmness of the pipe after welding, refer to Figure 7 and Figure 8 Two guide rods 141 are provided inside the electromagnetic slide 132, and a fixed platform 142 is provided between the two guide rods 141 for sliding together. Lugs 143 are provided on both sides of the fixed platform 142. The fixed platform 142 is located in the middle of the two guide rods 141. Springs are sleeved on both sides of the guide rods 141, one end of which abuts against the side wall of the fixed platform 142 and the other end abuts against the side wall of the electromagnetic slide 132. The electrode 133 is fixed on the fixed platform 142, and a number of arc blocks 144 that cooperate with the lugs 143 are alternately provided on both sides of the slide rail 131.

[0039] In the process of the electromagnetic slide 132 carrying the electrode 133 to move, the lugs 143 on both sides of the fixed platform 142 will alternately contact the arc blocks 144 on both sides of the slide rail 131. When the lugs 143 on one side contact the arc blocks 144, the fixed platform 142 and the electrode 133 are driven to move laterally to the other side through the extrusion effect, thereby expanding the melting area between the electrode 133 and the pipe, thereby increasing the width of the weld and ensuring the quality of the weld. In addition, the reciprocating movement of the electrode 133 left and right can keep the weld more uniform.

[0040] See Figure 2 and Figure 3The tightening mechanism 3 includes two outer fixing rings 31 symmetrically installed inside the welding cavity 13 by bolts, each outer fixing ring 31 is composed of two semi-arc outer rings 311, one of the semi-arc outer rings 311 is installed on the semi-arc pressure handle 14, and the other semi-arc outer ring 311 is installed on the clamping section 12; two inner fixing rings 32 are also fitted between the two outer fixing rings 31 inside the welding cavity 13, each inner fixing ring 32 is composed of two semi-arc inner rings 321, and the two semi-arc inner rings 321 are respectively installed on the corresponding semi-arc outer ring 311.

[0041] See Figure 7 The inner circumference of the inner fixed ring 32 is evenly provided with sliding grooves 322, and a push seat 323 that moves along the axial direction of the inner fixed ring 32 is provided inside the sliding groove 322. The side wall of the outer fixed ring 31 is provided with a mounting groove 312 at a position corresponding to the sliding groove 322, and a support 313 is fixedly provided in the mounting groove 312. The center position of the support 313 is provided with a wire hole 314; a push spring 315 in a compressed state is connected between the support 313 and the push seat 323.

[0042] See Figure 7 The push seat 323 is provided with a close contact module 324 which slides radially along the inner fixing ring 32 and presses against the pipe to be welded; Figure 3 and Figure 6 Each of the snap locks 15 includes a fixed semi-arc pressure handle 14 and a corresponding base 151 fixed on the clamping section 12. A locking groove 152 is provided on the base 151 fixed on the semi-arc pressure handle 14, and a locking claw 153 is installed on the base 151 fixed on the clamping section 12; a connecting block 155 is provided on the base 151 through a return spring 154, and the connecting block 155 can slide inside the base 151; the locking claw 153 cooperates with the connecting block 155.

[0043] See Figure 4 and Figure 6 The push-pull seat 323 inside each semi-arc inner ring 321 is commonly connected to a steel wire rope 156, and the other end of the steel wire rope 156 passes through the wire hole 314 on the corresponding position support 313 and the corresponding semi-arc outer ring 311 in turn, and finally passes through the connecting block 155 inside the corresponding snap lock 15. The spring coefficient of the reset spring 154 is much greater than the spring coefficient of the push-pull spring 315.

[0044] When the locking pawl 153 is engaged, the connecting block 155 is pressed against the locking pawl 153 and the connecting block 155 is retracted into the inner part of the clamping seat 151. At this time, the steel wire rope 156 loses the elastic effect of the return spring 154, and due to the action of the push spring 315, the push seat 323 is pushed to slide, thereby driving the two clamped pipe fittings closer to each other through the close-fitting module 324 at the upper end, further reducing the gap after the weld is spliced; the spring coefficient of the return spring 154 is much larger than the spring coefficient of the push spring 315, so that the distance between the two relative push seats 323 is the largest when the locking pawl 153 is not engaged, and when the locking pawl 153 is engaged, the elastic potential energy of the push spring 315 on the circumferential side can be used to make the pipe fittings clamped on both sides closer to each other.

[0045] See Figure 2 and Figure 7 The described close-fitting module 324 includes a pressing block 325 which is slidably arranged inside the pushing seat 323 through a spring. The end of the pressing block 325 away from the spring is Y-shaped, and the end of the pressing block 325 located inside the pushing seat 323 is provided with a ball that rolls and rubs with the pushing seat 323; and the outer wall of the pressing block 325 is provided with a clamping sleeve to limit the inside of the pushing seat 323; the Y-shaped section of the pressing block 325 protrudes from the outer wall of the pushing seat 323.

[0046] At the same time, when the upper semi-arc pressure handle 14 is buckled, the Y-shaped section of the pressing block 325 is pressed against the outer wall of the pipe fitting to keep it fixed, and the multiple pressing blocks 325 evenly arranged on the circumference can fully ensure its radial fixing effect on the pipe fitting; and the ball is set at one end of the pressing block 325 located inside the push seat 323 to better reduce the active friction of the pressing block 325, which can effectively promote the adaptive fixing of the pressing block 325 to fix the pipe fitting.

[0047] In the argon arc welding of elbow pipes, due to the irregular shape of the elbow pipes (the curvature at the bend changes, the pipe diameter may have deviations), stress concentration, and complex welding positions (such as horizontal fixation, vertical fixation, etc.), defects such as incomplete welding, pores, cracks, and undercuts are prone to occur. In order to improve the welding quality, it is necessary to thoroughly clean the oil, oxide scale, rust, etc. in the welding area of ​​the elbow pipe (the groove and the 20-30mm range on both sides) in the early stage; during the specific welding, in order to improve the assembly accuracy between the two pipe fittings as much as possible through automation, when the two pipe fittings are placed in the welding cavity 13, the semi-arc pressure handle 14 and the clamping section 12 are locked by the snap lock 15. In the process of buckling the locking claw 153, the connecting block 155 will be pressed to retract into the inside of the clamping seat 151. At this time, the push spring 315 will push the push seat 323 to slide, thereby driving the two fittings through the close-fitting module 324 at the upper end. The clamped pipes are brought closer to each other, further reducing the gap after the weld is spliced; then the control button is operated to energize the electromagnetic slide 132 and the electrode 133. After the electromagnetic slide 132 is energized, it moves around the slide rail 131. The electrode 133 is energized to generate a high-temperature arc (up to 3000°C or more) at the weld position between the pipes, melting the pipe at the weld position to form a molten pool, thereby forming a weld by self-melting of the pipe, and then welding the interface positions of the two pipes together; in the process of the electromagnetic slide 132 carrying the electrode 133 to move, the lugs 143 on both sides of the fixed platform 142 will alternately contact the arc blocks 144 on both sides of the slide rail 131, and the fixed platform 142 and the electrode 133 are driven to move back and forth laterally through the squeezing effect, thereby expanding the melting area between the electrode 133 and the pipe, thereby increasing the width of the weld and ensuring the quality of the weld.

[0048] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0049] Furthermore, the terms "first," "second," "number one," and "number two" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature designated as "first," "second," "number one," or "number two" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0050] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection; direct connection, or indirect connection through an intermediate medium; internal communication between two components, or interaction between two components, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0051] The embodiments of this specific implementation method are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A superheater tube bundle assembly elbow welding device, comprising a welding gun housing, characterized in that: The welding gun housing is provided with a welding mechanism inside, and both sides of the welding mechanism are provided with a pressing mechanism for pressing the pipe to be welded inwardly toward the weld position and a limiting mechanism for applying a pre-tightening force to the pipe in the direction of the weld; the pressing mechanism is located outside the limiting mechanism; wherein: The welding gun housing includes a hand-held section and a clamping section. The clamping section is provided with a welding cavity. The clamping section above the welding cavity is hingedly provided with two semi-arc pressure handles with the same radius and different widths. The two semi-arc pressure handles are locked to the clamping section by two snap locks respectively. An annular slide rail is provided inside the welding chamber, and the welding mechanism includes an electromagnetic slide seat provided inside the slide rail. An electrode is provided inside the electromagnetic slide seat for generating a high-temperature arc between the electrode and the pipe to be welded and melting the pipe to be welded to form a molten pool. The electrode is mounted on the electromagnetic slide seat via a fixed platform, and a plurality of arc blocks are alternately provided on both sides of the slide rail. Lugs are provided on both sides of the fixed platform for alternating contact with the arc blocks to enable the electrode to move back and forth laterally during welding to widen the weld seam. The tightening mechanism includes an outer fixing ring and an inner fixing ring arranged symmetrically, wherein the inner circumferential surface of the inner fixing ring is evenly provided with sliding grooves, wherein a pushing seat is provided in the sliding groove and moves along the axis direction of the inner fixing ring, and a close contact module is provided inside the pushing seat and slides radially along the inner fixing ring and presses against the pipe to be welded; Each of the snap locks comprises a fixed semi-arc pressure handle and a clamping seat fixed to two corresponding positions on the clamping section; a locking groove is provided on the clamping seat fixed to the semi-arc pressure handle, and a locking claw is installed on the clamping seat fixed to the clamping section; a connecting block is provided on the clamping seat via a return spring, and the connecting block can slide inside the clamping seat; the locking claw cooperates with the connecting block; The side wall of the outer fixed ring is provided with an installation groove at a position corresponding to the slide groove, and a support is fixedly arranged in the installation groove, and a compressed push spring is connected between the support and the push seat; the push seats inside each semi-arc inner ring are commonly connected to a steel wire rope, and the other end of the steel wire rope passes through the wire hole on the support at the corresponding position and the corresponding semi-arc outer ring in sequence, and finally passes through the connecting block inside the corresponding snap lock, and a wire hole is provided at the center position of the support; the spring coefficient of the reset spring is much greater than the spring coefficient of the push spring.

2. The superheater tube bundle assembly elbow welding device according to claim 1, characterized in that: The close-fitting module includes a pressure block that is slidably arranged inside the push seat through a spring. The end of the pressure block away from the spring is Y-shaped, and the outer wall of the pressure block is provided with a clamping sleeve to limit the inside of the push seat; the Y-shaped section of the pressure block protrudes from the outer wall of the push seat.

3. The superheater tube bundle assembly elbow welding device according to claim 1, characterized in that: Each of the outer fixing rings is composed of two semi-arc outer rings, one of which is installed on the semi-arc pressure handle, and the other semi-arc outer ring is installed on the clamping section; each of the inner fixing rings is composed of two semi-arc inner rings, and the two semi-arc inner rings are respectively installed on the corresponding semi-arc outer rings.

4. The superheater tube bundle assembly elbow welding device according to claim 1, characterized in that: Two guide rods are provided inside the electromagnetic slide, and a fixed platform is provided between the two guide rods for sliding together. The fixed platform is located in the middle of the two guide rods. Springs are provided on both sides of the guide rods to automatically reset the electrode when the lug contacts the arc block.

5. The superheater tube bundle assembly elbow welding device according to claim 1, characterized in that: The limiting mechanism includes two groups of push rods circumferentially arranged on the inner wall of the welding chamber, and both groups of push rods are inclined toward the welding mechanism. Each group of push rods includes a fixed cylinder evenly arranged on the inner wall of the welding chamber by a threaded manner. The interior of the fixed cylinder is connected to a telescopic rod by a spring sliding connection. The end of the telescopic rod facing the axis of the welding chamber is provided with a ball that contacts the outer wall of the pipe to be welded; the push rod is in rolling contact with the outer wall of the pipe through the ball, and applies a pre-tightening force to the pipe in the direction of the weld when the semi-arc pressure handle is buckled.

6. The superheater tube bundle assembly elbow welding device according to claim 1, characterized in that: The handheld section of the welding gun housing is provided with a control button for controlling the power supply and movement of the electromagnetic slide and the electrode.

7. The superheater tube bundle assembly elbow welding device according to claim 1, characterized in that: A perspective hole is provided on the wider semi-arc-shaped pressing handle, and a perspective glass is embedded in the perspective hole for observing the welding state inside the welding cavity.

8. The superheater tube bundle assembly elbow welding device according to claim 2, characterized in that: One end of the pressing block located inside the pushing seat is provided with a ball that rolls and rubs against the pushing seat.

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