Weld seam structure suitable for narrow gap water-cooled wall tube panel and welding process

Abstract

The present invention relates to the technical field of boiler manufacturing, and provides a weld seam structure suitable for a narrow gap water-cooled wall tube panel and a welding process. The weld seam structure comprises groove gaps formed between adjacent water-cooled wall tubes; joints are provided on the sides of the adjacent water-cooled wall tubes close to each other; the joints are distributed on the upper sides of the groove gaps, and the joints are communicated with the groove gaps; and the groove gaps comprise V-shaped grooves or U-shaped grooves. In addition to the original joints, adjacent water-cooled wall tubes are considered as a whole, and gaps formed between the water-cooled wall tubes are machined into groove gaps and welded with the joints, thereby increasing the thickness of a welding seam at a tangent point and the safety coefficient, facilitating ray radiographic inspection, and solving the technical problem of great hazards to the safe operation of units due to the fact that when the gaps between the adjacent water-cooled wall tubes are small, the welding quality at the tangent point position of the adjacent water-cooled wall tubes cannot be effectively guaranteed due to inconvenient observation, welding, and radiographic inspection.

Description

Weld structure and welding process suitable for narrow-gap water wall tube panel TECHNICAL FIELD

[0001] The present application relates to the technical field of boiler manufacturing, in particular to a weld structure and welding process suitable for narrow-gap water wall tube panel. BACKGROUND

[0002] The water wall is a main heating component of a power station boiler, which is distributed around the boiler furnace. The inside of the water wall is flowing water or steam, and the outside receives the heat radiation of the boiler furnace flame. Modern large-capacity boilers generally use membrane water walls. According to the thickness of the water wall tube, the water wall is generally assembled and welded on site using a V-shaped or U-shaped groove, but when the gap between adjacent water wall tubes is small, it is inconvenient to observe, weld and detect, so that the welding quality of the intersection position of adjacent water wall tubes cannot be effectively guaranteed, which brings great hidden dangers to the safe operation of the unit. SUMMARY

[0003] The present application provides a weld structure and welding process suitable for narrow-gap water wall tube panel to solve the technical problem that when the gap between adjacent water wall tubes is small, it is inconvenient to observe, weld and detect, so that the welding quality of the intersection position of adjacent water wall tubes cannot be effectively guaranteed, which brings great hidden dangers to the safe operation of the unit.

[0004] To solve the above technical problems, the present application discloses a weld structure suitable for narrow-gap water wall tube panel, which comprises a groove-shaped gap formed between adjacent water wall tubes, and a welding opening is arranged on the side of the adjacent water wall tubes close to each other, the welding opening is distributed on the upper side of the groove-shaped gap, and the welding opening is in communication with the groove-shaped gap.

[0005] Preferably, the groove-shaped gap comprises any one of a V-shaped groove and a U-shaped groove.

[0006] A welding process for welding a weld structure suitable for narrow-gap water wall tube panel, comprising the following steps:

[0007] Step 1: process the water wall tube to form a welding opening, process the gap between adjacent water wall tubes to form a groove-shaped gap, and then polish the surface of the water wall tube until the metal luster is exposed;

[0008] Step 2: bake the welding rod to the target temperature and place it in the welding rod heat preservation cylinder for standby;

[0009] Step 3: preheat the water wall tube to make each part of the material to be welded evenly heated;

[0010] Step 4: place the water wall tube on the welding device to form a groove-shaped gap between adjacent water wall tubes, and then weld it.

[0011] Step 5: use the oven gun to heat the weld and heat-affected zone of the water wall tube, and complete the purpose of hydrogen removal;

[0012] Step 6: after the hydrogen removal is completed, the weld is detected by flaw detection.

[0013] Preferably, the baking temperature of the welding rod in step 2 is 300-500℃, and the baking time is 0.5-3h.

[0014] Preferably, the welding current of the water wall tube in step 4 is 300-320A, the welding voltage is 22-27V, and the welding speed is 80-90mm / min.

[0015] Preferably, in step 5, when heating the weld and heat-affected zone of the water wall tube, a layer of asbestos is laid on the ground, the welded water wall tube is placed on the asbestos, and the asbestos is covered every certain length.

[0016] Preferably, the welding device comprises a base plate, a cavity is arranged in the middle of the base plate, a plurality of support seats one are uniformly arranged in the cavity along the front-rear direction, a support groove one is arranged at the upper end of the support seat one, a plurality of extension rods are uniformly arranged on the left side of the upper end of the base plate along the front-rear direction, the plurality of extension rods and the plurality of support seats one are correspondingly arranged, the extension rod is fixedly connected with a connecting block, the connecting block is slidably connected with a support seat two, a support groove two is arranged at the lower end of the support seat two, the support groove two is correspondingly communicated with the support groove one, a fixing block is connected with the upper end of the support seat two, a spring is fixedly arranged between the fixing block and the connecting block, a plurality of sliding blocks and a plurality of positioning holes are uniformly arranged on the right side of the upper end of the base plate along the front-rear direction, the sliding block is slidably connected with the fixing block along the vertical direction, the sliding block and the extension rod are slidably connected along the front-rear direction of the base plate, a fixed shaft is fixedly arranged in the sliding block, one end of the fixed shaft is rotatably connected with the support seat one, a threaded hole is arranged on the side of the fixed shaft away from the support seat one, the threaded hole is threadedly connected with a threaded rod, and the threaded rod is correspondingly matched with the positioning hole.

[0017] Preferably, the upper and lower ends and the left and right sides of the base plate are symmetrically provided with mounting mechanisms, the mounting mechanism comprises a plurality of mounting blocks, the plurality of mounting blocks are uniformly arranged along the front-rear direction, a driving threaded rod is rotatably arranged between the mounting blocks on the left and right sides, a threaded section of the driving threaded rod is threadedly connected with a movable block, a cylindrical section of the driving threaded rod penetrates through the mounting block on the left side and is fixedly connected with a driving motor, the driving motor is fixedly connected with the mounting block, a working cavity is arranged in the movable block, a sliding plate is slidably arranged in the working cavity, the sliding plate is fixedly connected with an electric telescopic rod and an automatic welding head, the electric telescopic rod is fixedly arranged in the working cavity, the automatic welding head is slidably connected with the movable block, and the automatic welding head is connected with the welding rod.

[0018] Preferably, it also comprises a preheating temperature control method of the water wall tube, comprising the following steps:

[0019] Step 7: Calculate the target preheating temperature of the water-cooled wall pipe according to formula (1);

[0020] (1)

[0021] wherein, T is the target preheating temperature of the water-cooled wall pipe, η is the welding heat efficiency when the automatic welding head works, U is the welding voltage when the automatic welding head works, I is the arc current when the automatic welding head works, S is the width of the groove-shaped gap, K is a natural constant, L is the distance between the automatic welding head and the groove-shaped gap, λ is the thermal conductivity of the water-cooled wall pipe, ε is the maximum deformation allowed by the water-cooled wall pipe, α is the linear expansion coefficient of the water-cooled wall pipe, t is the thickness of the water-cooled wall pipe;

[0022] Step 8: Detect the temperature of the water-cooled wall pipe by the temperature detector, and stop preheating the water-cooled wall pipe when the temperature of the water-cooled wall pipe detected by the temperature detector reaches the target preheating temperature, and start welding the water-cooled wall pipe.

[0023] The technical solutions of the present application will be further described in detail below by means of the accompanying drawings and examples.

[0024] Compared with the prior art, the present application has the following beneficial effects:

[0025] In addition to the original weld, the adjacent water-cooled wall pipes are considered as a whole, the gap between the water-cooled wall pipes is processed into a groove-shaped type and welded together with the weld, which increases the weld thickness and safety factor at the cutting point, and facilitates the radiographic inspection. DETAILED DESCRIPTION

[0026] The accompanying drawings are used to provide a further understanding of the present application, and constitute a part of the specification, together with the embodiments of the present application, to explain the present application, and do not constitute a limitation on the present application. In the drawings:

[0027] Fig. 1 is a structural schematic diagram of the present application;

[0028] Fig. 2 is a schematic diagram of the slider structure of the present application;

[0029] Fig. 3 is an enlarged structural schematic diagram of the A area in Fig. 1;

[0030] Fig. 4 is a schematic diagram of the movable block structure of the present application.

[0031] In the figure: 1, base plate; 2, mounting block; 3, driving threaded rod; 4, driving motor; 5, movable block; 6, automatic welding head; 7, working cavity; 8, electric telescopic rod; 9, sliding plate; 10, telescopic rod; 11, connecting block; 12, spring; 13, fixed block; 14, support seat I; 15, support groove I; 16, water-cooled wall pipe; 17, support seat II; 18, support groove II; 19, sliding block; 20, fixed shaft; 21, positioning hole; 22, cavity; 23, threaded hole; 24, threaded rod. DETAILED DESCRIPTION

[0032] The preferred embodiments of the present application will be described herein below with reference to the drawings; it should be understood that the preferred embodiments described herein are intended to describe and explain the present application only, and are not intended to limit the present application.

[0033] In addition, the description such as "first", "second" and the like in the present application is only for the purpose of description, and does not mean to particularly indicate the order or sequence, nor to limit the present application, which is merely to distinguish the components or operations described by the same technical terms, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second" can explicitly or implicitly include at least one of the features. In addition, the technical solutions and technical features of various embodiments can be combined with each other, but it must be based on the realization of a person skilled in the art, when the combination of technical solutions appears to be contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, nor within the protection scope required by the present application.

[0034] The present application provides the following embodiments

[0035] Embodiment 1

[0036] The embodiment of the present application provides a weld structure suitable for narrow gap water-cooled wall pipe screen, which comprises a bevel type gap formed between adjacent water-cooled wall pipes 16, and a welding opening is arranged on the side of the adjacent water-cooled wall pipes 16 close to each other, the welding opening is distributed on the upper side of the bevel type gap, and the welding opening is in communication with the bevel type gap.

[0037] The bevel type gap comprises any one of a V-shaped groove and a U-shaped groove.

[0038] The beneficial effects of the above technical solution are:

[0039] In addition to the original weld gap, the adjacent water cooled wall tube 16 is considered as a whole, the gap between the water cooled wall tube 16 is processed into a bevel type and welded together with the weld gap, the weld thickness and safety factor at the cutting point are increased, and the radiographic detection is facilitated, the technical problem that the welding quality of the cutting point position of the adjacent water cooled wall tube cannot be effectively guaranteed due to the inconvenience of observation, welding and detection when the gap between the adjacent water cooled wall tubes is small, and great hidden trouble is brought to the safe operation of the unit.

[0040] Embodiment 2

[0041] On the basis of embodiment 1, a welding process for welding a weld structure suitable for a narrow gap water cooled wall tube panel, comprising the following steps:

[0042] Step 1: process the water cooled wall tube 16 to form a weld gap, process the gap between the adjacent water cooled wall tubes 16 to form a bevel type gap, and then polish the surface of the water cooled wall tube 16 until the metal luster is exposed;

[0043] Step 2: bake the electrode to the target temperature and place it in the electrode holding cylinder for standby;

[0044] Step 3: preheat the water cooled wall tube 16 to make the parts of the material to be welded uniformly heated;

[0045] Step 4: place the water cooled wall tube 16 on the welding device to form a bevel type gap between the adjacent water cooled wall tubes 16, and then weld it;

[0046] Step 5: heat the weld and heat affected zone of the water cooled wall tube 16 with a baking gun to complete the purpose of hydrogen removal;

[0047] Step 6: after hydrogen removal, detect the weld;

[0048] The baking temperature of the electrode in step 2 is 300-500 DEG C, and the baking time is 0.5-3h;

[0049] The welding current of the water cooled wall tube 16 in step 4 is 300-320A, the welding voltage is 22-27V, and the welding speed is 80-90mm / min;

[0050] In step 5, when heating the weld and heat affected zone of the water cooled wall tube 16, a layer of asbestos is laid on the ground, the welded water cooled wall tube 16 is placed on the asbestos, and the asbestos is covered every certain length.

[0051] The beneficial effects of the above technical scheme are:

[0052] Before welding, the water cooled wall pipe 16 is preheated to make each part of the water cooled wall pipe 16 uniformly heated, and after welding, the water cooled wall pipe 16 is immediately covered with thermal insulation cotton to avoid cracks caused by rapid cooling of the water cooled wall pipe 16 after welding. After welding, hydrogen is removed, the welding seam and the heat affected zone are heated by an oven gun, one end is immediately covered with asbestos after heating, and then detection is performed. If it is unqualified, repair welding is required. The entire processing process ensures that no cracks occur at the welding seam, and the product detection is unqualified. The repair welding site needs to be preheated to above 200 DEG C before welding. Manual tungsten argon arc welding is used for repair welding, the welding wire is TIG-R31, and the repair welding site is immediately wrapped with asbestos after repair welding to slow cool. After repair welding is completed, the repair welding site is detected again.

[0053] Example 3

[0054] On the basis of example 2, as shown in figures 1-4, the welding device comprises a base plate 1, the middle part of the base plate 1 is provided with a cavity 22, a plurality of support seats one 14 are uniformly arranged in the cavity 22 along the front and back direction, the upper end of the support seat one 14 is provided with a support groove one 15, a plurality of telescopic rods 10 are uniformly arranged on the left side of the upper end of the base plate 1 along the front and back direction, the plurality of telescopic rods 10 and the plurality of support seats one 14 are one-to-one corresponding, the telescopic rod 10 is fixedly connected with a connecting block 11, the connecting block 11 is slidingly connected with a support seat two 17, the lower end of the support seat two 17 is provided with a support groove two 18, the support groove two 18 is in communication with the support groove one 15, the upper end of the support seat two 17 is connected with a fixed block 13, a spring 12 is fixedly arranged between the fixed block 13 and the connecting block 11, a plurality of sliding blocks 19 and a plurality of positioning holes 21 are uniformly arranged on the right side of the upper end of the base plate 1 along the front and back direction, the sliding block 19 is slidingly connected with the fixed block 13 along the vertical direction, the sliding block 19 and the telescopic rod 10 are slidingly connected along the front and back direction of the base plate 1, a fixed shaft 20 is fixedly arranged in the sliding block 19, one end of the fixed shaft 20 is fixedly connected with the support seat one 14, the side of the fixed shaft 20 away from the support seat one 14 is provided with a threaded hole 23, the threaded hole 23 is threadedly connected with a threaded rod 24, and the threaded rod 24 is correspondingly matched with the positioning hole 21;

[0055] The upper and lower ends and the left and right sides of the substrate 1 are symmetrically provided with mounting mechanisms, the mounting mechanisms include a plurality of mounting blocks 2, the plurality of mounting blocks 2 are uniformly arranged on the substrate 1 along the front-rear direction, the mounting blocks 2 on the left and right sides are rotatably provided with driving threaded rods 3, the driving threaded rods 3 are correspondingly arranged between adjacent sliding blocks 19, the threaded sections of the driving threaded rods 3 are threadedly connected with movable blocks 5, the cylindrical sections of the driving threaded rods 3 are fixedly connected with driving motors 4 penetrating through the mounting blocks 2 on the left side, the driving motors 4 are fixedly connected with the mounting blocks 2, the inside of the movable block 5 is provided with a working cavity 7, the working cavity 7 is slidably provided with a sliding plate 9, the sliding plate 9 is fixedly connected with an electric telescopic rod 8 and an automatic welding head 6, the electric telescopic rod 8 is fixedly arranged in the working cavity 7, the automatic welding head 6 is slidably connected with the movable block 5, and the automatic welding head 6 is connected with a wire feeder through a wire feeding pipe.

[0056] The above technical scheme has the beneficial effects that:

[0057] The water cooling wall pipe 16 to be welded is placed in the support groove one 15, the lower end of the water cooling wall pipe 16 is supported, the telescopic rod 10 is controlled to retract, the telescopic rod 10 drives the connecting block 11 to move downward, the connecting block 11 drives the fixed block 13 to move downward through the spring 12, the fixed block 13 drives the support seat two 17 to move downward, the support groove two 18 at the lower end of the support seat two 17 moves downward, the upper end of the water cooling wall pipe 16 is positioned, after the support seat two 17 cannot move downward, the support seat two 17 and the sliding block 19 relatively slide, the spring 12 is compressed, under the elastic action of the spring 12, the positioning of the support seat two 17 on the water cooling wall pipe 16 is more stable, the support groove one 15 and the support groove two 18 are semicircular structures, and the diameters of the support groove one 15 and the support groove two 18 are smaller than the diameter of the water cooling wall pipe 16, so as to avoid that the support groove one 15 and the support groove two 18 shield the welding opening and the gap between the bevels of the water cooling wall pipe 16;

[0058] After positioning and fixing the water-cooled wall pipe 16, the threaded rod 24 is rotated to separate the threaded rod 24 from the positioning hole 21 and the threaded hole 23, and then the fixed shaft 20 is pushed to move forward and backward, the fixed shaft 20 drives the sliding block 19 and the support seat one 14 to move forward and backward, the sliding block 19 drives the support seat two 17 to move forward and backward, thereby driving the water-cooled wall pipe 16 to move forward and backward, after the water-cooled wall pipe 16 moves to the target position, the threaded rod 24 is tightened with the positioning hole 21 and the threaded hole 23, so that the support seat one 14 and the support seat two 17 no longer move forward and backward, the purpose of adjusting the gap between different water-cooled wall pipes 16 is achieved, and the gap between the water-cooled wall pipes 16 is avoided to be too small, which is not convenient for observation, welding and detection of the water-cooled wall pipe 16, then the electric telescopic rod 8 is controlled to extend and retract, the automatic welding head 6 is driven by the electric telescopic rod 8 to move towards the water-cooled wall pipe 16, the wire feeder feeds welding wire to the automatic welding head 6 through the wire feeding pipe, until it moves to the target position, then the driving motor 4 is controlled to work, the driving motor 4 drives the driving threaded rod 3 to rotate, and the driving threaded rod 3 drives the movable block 5 to move along the length direction of the water-cooled wall pipe 16 when rotating, so as to complete the automatic welding of the water-cooled wall pipe 16, without manual welding, saving time and effort, the support seat one 14 and the support seat two 17 can be made of heat preservation material to reduce the cooling speed of the water-cooled wall pipe 16, the automatic welding head 6 is arranged above and below, and is controlled to work by the driving motor 4 arranged above and below respectively, without interference, and can be used for front welding or front and back welding of the water-cooled wall pipe 16 according to requirements.

[0059] Example 4

[0060] On the basis of example 1, as shown in FIG. 1-FIG. 3, it further includes a preheating temperature control method of the water-cooled wall pipe 16, including the following steps:

[0061] Step 7: calculate the target preheating temperature of the water-cooled wall pipe 16 according to formula (1);

[0062] ;(1)

[0063] wherein, is the target preheating temperature of the water-cooled wall pipe 16, is the welding heat efficiency when the automatic welding head 6 works, is the welding voltage when the automatic welding head 6 works, is the arc current when the automatic welding head 6 works, is the width of the groove gap, is a natural constant, is the distance between the automatic welding head 6 and the groove gap, is the thermal conductivity of the water-cooled wall pipe 16, is the maximum deformation amount allowed by the water-cooled wall pipe 16, is the linear expansion coefficient of the water-cooled wall pipe 16, for the thickness of the water wall tube 16;

[0064] Step 8: The temperature of the water wall tube 16 is detected by the temperature detector, and after the temperature of the water wall tube 16 detected by the temperature detector reaches the target preheating temperature, the preheating of the water wall tube 16 is stopped, and the welding of the water wall tube 16 is started.

[0065] The beneficial effects of the above technical solution are:

[0066] The target preheating temperature of the water wall tube 16 is calculated according to formula (1), and then the temperature of the water wall tube 16 is detected by the temperature detector, and after the temperature of the water wall tube 16 detected by the temperature detector reaches the target preheating temperature, the preheating of the water wall tube 16 is stopped, and the welding of the water wall tube 16 is started. By setting a suitable preheating temperature, the preheating temperature is avoided to be too low, and the welding temperature is too large when welding, which causes the temperature difference on the water wall tube 16 to be too large, so that the deformation amount of the water wall tube 16 at the gap of the bevel type is too large, which affects the reliability of the weld structure.

[0067] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application belong to the scope of the claims of the present application and their equivalents, the present application also intends to include these modifications and variations.

Claims

1. A weld structure suitable for use in a narrow gap water wall panel, characterized by: The gap between the adjacent water-cooled wall pipes (16) is a bevel-shaped gap, and the side of the adjacent water-cooled wall pipes (16) close to each other is provided with a welding opening, which is distributed on the upper side of the bevel-shaped gap and communicates with the bevel-shaped gap.

2. The weld structure suitable for use in a narrow-gap, water-cooled wall panel as defined in claim 1, wherein: The bevel-shaped gap includes any one of a V-shaped groove and a U-shaped groove.

3. A welding process for welding the weld structure suitable for narrow gap water wall panel as claimed in any one of claims 1-2, characterized by: The method comprises the following steps: Step 1: processing the water-cooled wall pipes (16) to form the welding opening, processing the gap between the adjacent water-cooled wall pipes (16) to form the bevel-shaped gap, and then polishing the surface of the water-cooled wall pipes (16) until the metal luster is exposed; Step 2: baking the electrode to the target temperature and placing it in the electrode holding cylinder for standby; Step 3: preheating the water-cooled wall pipes (16) to make the parts of the material to be welded uniformly heated; Step 4: placing the water-cooled wall pipes (16) in the welding device to form the bevel-shaped gap between the adjacent water-cooled wall pipes (16), and then welding them; Step 5: heating the weld and heat-affected zone of the water-cooled wall pipes (16) with a baking gun to complete the purpose of hydrogen removal; Step 6: after the hydrogen removal is completed, the weld is detected.

4. The welding process of claim 3, wherein: The baking temperature of the electrode in step 2 is 300-500℃, and the baking time is 0.5-3h.

5. The welding process of claim 3, wherein: The welding current in step 4 is 300-320A, the welding voltage is 22-27V, and the welding speed is 80-90mm / min.

6. The welding process of claim 3, wherein: In step 5, when heating the weld and heat-affected zone of the water-cooled wall pipes (16), a layer of asbestos is laid on the ground, the welded water-cooled wall pipes (16) are placed on the asbestos, and the asbestos is covered every certain length of heating.

7. The welding process of claim 3, wherein: The welding device comprises a base plate (1), a cavity (22) is arranged in the middle of the base plate (1), a plurality of support seats (14) are uniformly arranged in the cavity (22) along the front-rear direction, the upper end of the support seat (14) is provided with a support groove (15), a plurality of telescopic rods (10) are uniformly arranged on the left side of the upper end of the base plate (1) along the front-rear direction, the telescopic rod (10) and the support seat (14) are one-to-one corresponding, the telescopic rod (10) is fixedly connected with a connecting block (11), the connecting block (11) is slidably connected with a support seat (17), the lower end of the support seat (17) is provided with a support groove (18), the support groove (18) is in communication with the support groove (15), the upper end of the support seat (17) is connected with a fixed block (13), the fixed block (13) and the connecting block (11) are fixedly provided with a spring (12), a plurality of sliding blocks (19) and a plurality of positioning holes (21) are uniformly arranged on the right side of the upper end of the base plate (1) along the front-rear direction, the sliding block (19) is slidably connected with the fixed block (13) along the vertical direction, the sliding block (19) and the telescopic rod (10) are slidably connected along the front-rear direction of the base plate (1), a fixed shaft (20) is fixedly arranged in the sliding block (19), one end of the fixed shaft (20) is rotatably connected with the support seat (14), the side, away from the support seat (14), of the fixed shaft (20) is provided with a threaded hole (23), the threaded hole (23) is threadedly connected with a threaded rod (24), and the threaded rod (24) is correspondingly matched with the positioning hole (21).

8. The welding process of claim 7, wherein: The upper and lower ends and the left and right sides of the base plate (1) are symmetrically provided with mounting mechanisms, the mounting mechanism comprises a plurality of mounting blocks (2), the mounting blocks (2) are uniformly arranged on the base plate (1) along the front-rear direction, a driving threaded rod (3) is rotatably arranged between the mounting blocks (2) on the left and right sides, the threaded section of the driving threaded rod (3) is threadedly connected with a movable block (5), the cylindrical section of the driving threaded rod (3) penetrates through the mounting block (2) on the left side and is fixedly connected with a driving motor (4), the driving motor (4) is fixedly connected with the mounting block (2), the inside of the movable block (5) is provided with a working cavity (7), a sliding plate (9) is slidably arranged in the working cavity (7), the sliding plate (9) is fixedly connected with an electric telescopic rod (8) and an automatic welding head (6), the electric telescopic rod (8) is fixedly arranged in the working cavity (7), the automatic welding head (6) is slidably connected with the movable block (5), and the automatic welding head (6) is connected with an electrode.

9. The welding process of claim 3, wherein: The preheating temperature control method of the water cooling wall pipe (16) comprises the following steps: Step 7: the target preheating temperature of the water cooling wall pipe (16) is calculated according to formula (1); ；（1） wherein a target preheat temperature for the water wall tubes (16), to automatically weld the head (6) with a welding heat efficiency, for the welding voltage during the operation of the automatic welding head (6), for automatically welding the arc current during the operation of the head (6), for the width of the groove type gap, is a natural constant, to automatically weld the head (6) and the gap of the bevel type, for the thermal conductivity of the water-cooled wall tubes (16), the maximum deformation allowed for the waterwall tube (16), for the linear expansion coefficient of the water-cooled wall tube (16), the thickness of the water cooling wall pipe (16); Step 8: the temperature of the water cooling wall pipe (16) is detected by a temperature detector, and after the temperature of the water cooling wall pipe (16) detected by the temperature detector reaches the target preheating temperature, the preheating of the water cooling wall pipe (16) is stopped, and the welding of the water cooling wall pipe (16) is started.

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