CN114952050A - A composite welding method suitable for large-diameter thick-walled cylinders above 8mm - Google Patents

Abstract

The invention discloses a composite welding method suitable for a large-diameter thick-wall cylinder body with the diameter of more than 8mm, which comprises the following steps of: aiming at a large-diameter thick-wall cylinder with the diameter of more than 8mm, the joint is a butt joint, a reverse Y-shaped groove is formed, the angle of the groove is 60-70 degrees, and the truncated edge is 5 mm; selecting a welding wire according to the thickness and the material of the weldment; the inner wall is additionally provided with a positioning support, the distance between the two cylinders is adjusted according to the assembly gap between the two cylinders read by the supporting sliding mechanism, and the misalignment amount between the two cylinders is adjusted by adjusting the cylinder support, so that the welding seam gap and the misalignment amount of the workpiece to be welded meet the welding requirement; manual TIG spot welding positioning is carried out on the outer side; the plasma + TIG electric arc + SAW composite welding is completed by adopting a welding combination mode that plasma outside the cylinder is not added with wire in the front for single-pass backing welding, TIG is added with cold wire after filling the cover surface, grinding wheel back chipping is carried out inside the cylinder, and SAW multi-pass multi-layer welding is carried out for filling the cover surface, wherein the performance of the steel welding joint meets the requirements of the welding process evaluation of pressure-bearing equipment for NB/T47014 plus 2011 and stainless steel and heat-resistant steel plates for pressure-bearing equipment and steel belts GB/T24511-2017.

Description

A composite welding method suitable for large-diameter thick-walled cylinders above 8mm

technical field

The invention relates to the field of cylinder body welding, in particular to a composite welding method for a large-diameter thick-walled cylinder body.

Background technique

Due to the special use environment and working conditions of pressure vessels, in high temperature and high pressure and corrosive liquid and gas environments, the metal and welding seams of pressure vessels are required to be high, and the welding process plays a vital role in the manufacturing process of pressure vessels. The welding performance of the pressure vessel directly determines the quality and safety performance of the pressure vessel. With the development of domestic petrochemical and steel manufacturing technology, the use of large-diameter thick-walled pressure vessels above 8mm is increasing. As the diameter of the cylinder of the pressure vessel becomes larger and the wall thickness becomes thicker, higher requirements are put forward for the pairing and circumferential seam welding process of the cylinder.

Plasma+TIG welding method is a composite welding method widely used in chemical containers at present. It has the advantages of good weld quality and high welding efficiency. Compared with SAW welding, every 1000mm weld saves nearly 10 times of welding materials and saves money. A large part of the cost of welding consumables has good economic benefits. The existing plasma + TIG welding method usually adopts the method that the plasma is not added before the wire to make the bottom, and the TIG arc is added with the cold wire to fill the cover surface. Through the plasma arc energy concentration, high productivity, fast welding speed and high TIG arc welding seam The characteristics of single-sided welding and double-sided forming are realized. However, for large-diameter thick-walled cylinders above 8mm, if this welding process is used to weld outside the cylinder, defects such as incomplete penetration and fusion will appear in the weld, and most of the plasma + TIG double-gun welding equipment is not suitable for inner wall welding. Cylinder, the application is not flexible enough, and the welding efficiency is low, which increases the production cost of the enterprise. In addition, the assembly requirements of the cylinder before butt welding by plasma welding are relatively high, and the assembly gap of the large-diameter and thick-walled cylinder is not easy to control. The quality problem of solder leakage.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a composite welding method suitable for large-diameter thick-walled cylinders above 8 mm. In order to solve the problem of welding the large-diameter thick-walled cylinders above 8 mm in stainless steel, the plasma+TIG welding method is adopted, and the welding seam penetrates The problems of poor performance, low welding efficiency, and high requirements for pre-welding assembly are controlled by adjusting the inner wall positioning support to control the gap and misalignment between the two cylinders, so as to meet the high requirements of the cylinder assembly before plasma welding butt welding. Plasma+TIG arc and automatic SAW welding improve the welding quality and efficiency of large-diameter thick-walled cylinders, and provide a composite welding method suitable for large-diameter thick-walled cylinders above 8mm. The invention adopts the combined welding method of plasma arc + TIG arc + SAW, the welding efficiency is improved than that of plasma + TIG, the welding thickness range is increased, the penetration stability of the back welding seam is increased, and the 8mm-25mm thick large-diameter thick-walled cylinder is realized. Efficient and stable welding of the body. The plasma arc+TIG arc+SAW combined welding method of the invention is composed of plasma arc, TIG arc and SAW. During welding, the outside of the cylinder adopts plasma single-pass bottom welding without wire, and TIG and cold wire fill the cover for the under-welded parts. Surface, after the internal grinding wheel is cleaned, SAW multi-layer multi-pass welding fills the welding combination of the cover surface, the performance of the steel welded joint meets the welding process qualification of pressure equipment NB/T 47014-2011 and the stainless steel and resistant steel for pressure equipment. The requirements of GB/T24511-2017 for hot steel plates and strips, using the plasma + TIG welding method, the welding seam quality is good, the welding material cost is saved, the welding seam shape is beautiful, the welding efficiency is high, and the SAW is convenient for internal welding, and the weld bead quality is high The advantages of the plasma + TIG welding method are improved, and the welding efficiency of large-diameter thick-walled cylinders above 8mm is low, not suitable for inner wall welding, and the welding thickness is limited.

In order to solve the technical problem of the present invention, the proposed technical scheme is:

The composite welding method includes plasma arc, TIG arc, and SAW, and adopts the composite welding method to connect the grooves of the large-diameter thick-walled cylinders in stainless steel with a diameter of more than 8 mm;

The plasma + TIG welding device adopts the circular seam P + T welding system; the SAW welding device adopts a special cross-arm submerged arc automatic welding machine, which penetrates the machine head into the barrel for welding.

Specific steps are as follows:

1) Design the groove for composite welding of large-diameter and thick-walled cylinders according to the material and wall thickness of the workpiece to be welded: the stainless steel parts to be welded have a reverse Y-shaped groove;

2) Selection of welding cylinder thickness and material: the diameter of the stainless steel cylinder is 1000-3000mm, and the thickness is 8-25mm.

3) Selection of welding wire type and diameter: For TIG welding, use ER308L welding wire with a diameter of Φ1.2mm; for SAW welding, use a welding wire with a diameter of Φ3.2mm when the thickness of the barrel is less than 12mm; when the thickness of the barrel exceeds 12mm, Welding wire with a diameter of Φ4.0mm is used.

4) Before welding, machine grooves on both sides of the welding seam of the cylinder body, and clean up impurities such as oil stains and burrs on both sides of the welding seam, so that the surface can reveal the true color of the metal;

5) Lift the cleaned workpiece to be welded on the roller frame, install positioning supports on the inner walls of the cylinders on both sides, and adjust the distance between the two cylinders according to the pairing gap between the two cylinders read by the support sliding mechanism. Adjust the cylinder support to adjust the amount of misalignment between the two cylinders, so that the weld gap and misalignment of the workpiece to be welded meet the requirements of automatic welding, and the inner wall is rounded. The positioning support includes cylinder support (1) and support The sliding mechanism (2) has two parts.

The cylinder is supported by a support plate (3), a support plate (4a), an adjusting ring (5), an upper slider (6), a lower slider (7), a nut (8), a threaded rod (9), and a support rod (4b), a guide plate (10), a guide rod (11), a limit block (12), a fixed block (13), an arc-shaped plate (14) and a rotating handle (15). The support plate (3) is circular, and four pairs of support plates (4a) are evenly arranged on the edge of the support plate (3). The support plates (4a) are welded to connect the adjustment ring (5) and the support plate (3). for the cuboid. The upper and lower sliding blocks are respectively installed on both ends of the adjusting ring (5), and each lower sliding block (7) is machined with a thread which is matched with the upper sliding block (6), and is used for passing through the adjusting ring (5) and the The upper slider (6) is screwed. The number of upper and lower sliding blocks is 4 pairs, and the upper and lower sliding blocks are arc-shaped bottom surfaces in contact with the adjusting ring (5) and horizontal with holes away from the bottom surface of the adjusting ring (5). The support rod (4b) is fixedly connected with the upper slide block (6) and the limit block (12), and each upper slide block (6) and the limit block (12) are connected with two support rods (4b). The threaded rod (9) passes through the slider and the guide plate (10) to rotate to connect the limit block (12), and is fixed by the nut (8). The number of threaded rods (9) is 8, of which 4 are 9) The angle is adjustable and the rest are fixed. The number of nuts (8) corresponds to the threaded rod (9). Two guide rods (11) are slidably connected in the limit block (12), and the fixing block (13) is fixedly connected with the guide rod (11) and the arc-shaped plate (14), and one end of the arc-shaped plate (14) is processed with a fixed Block (13) mating external thread.

The supporting sliding mechanism (2) is composed of a fixing block (16), a lead screw (17), a guide rod (18), a rocker arm (18), a bolt (20) and a fixing plate (21). The lead screw (17) passes through the central holes supported by the two disc-shaped cylindrical bodies respectively. The left end of the lead screw (17) is rotatably connected to the fixing block (16), and the right end of the lead screw (17) is fixedly connected to the rocker arm (18) through the fixing plate (21). ). Four guide rods (18) are slidably connected in the two cylinder supports, and the guide rods (18) are fixedly connected with the fixing block (16) and the support plate (3) of the right cylinder support (1a). The lower end of the rocker arm (18) is connected with the fixing plate (21) by bolts (20) to prevent rotation, and the positions of the mounting bolts (20) of the rocker arm (18) and the fixing plate (21) are provided with matching bolt holes. .

Further, the upper sliding block (6), the lower sliding block (7) and the threaded rod (9) are screwed on the adjustment ring (5), and the cylinder support (1) is adjusted in the adjustment circle by changing the upper and lower sliders. For the position of the ring (5), select a suitable support point to support the cylinder.

6) Installation of back protection tooling or drag cover: determined according to the diameter and wall thickness of the cylinder, generally in the form of a width of 60m~80mm and a length of 100mm~120mm; for an external protective cover to the welded joint, the gas flow rate is 10~15L/min;

7) Spot welding the positioning cylinder directly on the outside by manual TIG: generally, the penetration depth is about 2mm, the welding current is 100A, the length of the solder joint is about 5mm, the width of the solder joint is 3mm, the welding discontinuity is 100mm, and the transition between the head and the tail is polished into a smooth and gentle slope. . If there are cracks and other defects, they should be completely ground off and re-spot welding.

8) Perform plasma+TIG+SAW composite welding treatment on the stainless steel cylinder, and set the composite welding parameters before welding arc:

The welding voltage used in plasma welding is 29~31V, the welding current is 240~260A, the welding speed range is 150~200mm/min, and the polarity of the welding power source is DC positive connection; the central axis of the plasma welding torch is perpendicular to the tangent of the ring seam, does not swing, and the welding torch is conductive The distance from the nozzle to the workpiece ranges from 10 to 15 mm, and the tungsten electrode is retracted by 2.8 mm;

The welding voltage used by TIG is 17~19V, the welding current is 230~250A, the wire feeding speed is 1200~1500mm/min, the welding speed range is 160~200mm/min, and the polarity of the welding power source is DC positive connection; the TIG welding torch is normally vertical, and there are Swing, the yaw speed is 1500mm/min, the left swing distance is 2.3mm, the right swing distance is 2.3mm, the left stop time is 0.2s, the right stop time is 0.2s, the distance from the conductive nozzle of the welding torch to the workpiece is 20~30mm, the distance between the tungsten electrode and the workpiece Range 10～15mm;

When the wire diameter is Φ3.2mm, the welding current used by SAW is 380～420A, the welding voltage is 28～32V, and the line energy is 12.77～20.16KJ/cm; when the wire diameter is Φ4.0mm, the welding current used by SAW is 500～550A, and the welding voltage is 30 ～36V, line energy 18.0～29.7KJ/cm, polarity of welding power source is DC reverse, welding speed range is 400～500mm/min; distance range from welding torch conductive nozzle to workpiece is 32～40mm;

Welding path planning: First, make a bottom welding with plasma arc without wire on the front blunt edge of the welding seam, then fill and cover the unwelded part with TIG arc and cold wire, and grind the back of the welding seam with a special stainless steel grinding wheel. Metallic luster, and finally SAW multilayer multi-pass welding at the back groove of the weld; when welding, start the plasma arc first, after about 10s, start the TIG arc for welding, when the plasma torch welding exceeds the arc starting point 15 ~ 20mm, start In the progressive arc extinguishing procedure, the plasma arc is turned off first, and after 10s, the arc is gradually extinguished in TIG welding.

9) Clean the welded seam until the surface appears metallic luster.

In order to ensure a better welding effect, in step 8), the arc should be avoided as far as possible from the spot welding seam, and the welding process should be filled with shielding gas. min, the gas supply time is 3s in advance, and the argon gas continues to circulate for 15s after the arc is interrupted.

In order to ensure the welding effect, during the automatic SAW multi-layer multi-pass welding in step 8), the temperature between the layers should be controlled to be less than 150 °C. Considering that the slag shell is easy to fall off, it is not necessary to use a stainless steel wire brush to polish and weld each layer after welding. The impurities on both sides of the seam and the welding seam, whether to grind or not can be determined according to the fusion and forming of the welding seam.

In order to ensure the welding effect, as the thickness of the welding seam increases, the operator can observe the welding seam formation in the molten pool at any time through the arc monitoring system. The distance between the nozzle and the welding seam, adjust the welding current, welding speed, wire feeding speed, and always keep the distance between the tip of the tungsten electrode and the workpiece unchanged. Reach into place to avoid TIG arc drift and improve weld formation.

The workpiece material to be welded described in step 1) is stainless steel.

For the reverse Y-shaped groove described in step 1), the thickness of the blunt edge is 5 mm, and the angle of the groove is controlled at 60° to 70°.

The protective gas described in step 6) and step 9) is a purity of 99.99% argon or 95% argon+5% hydrogen; the plasma arc and TIG arc described in step 8) are all controlled by automatic start and stop, wherein TIG The arc start and stop lag the plasma arc by 10s.

The weld gap and misalignment of the workpiece to be welded described in step 5) should not exceed 0.5mm.

The positions of the rocker arm (18) and the mounting bolt (20) of the fixing plate (21) described in step 5) are provided with matching bolt holes.

Beneficial effects:

(1) The present invention adopts the combined welding method of plasma arc+TIG arc+SAW, the welding efficiency is improved than that of plasma+TIG, the thickness range of welding is increased, the penetration stability of the back welding seam is increased, and a large diameter of 8mm-25mm is realized. Efficient and stable welding of thick-walled cylinders.

The plasma arc+TIG arc+SAW combined welding method of the invention consists of plasma arc, TIG arc and SAW. During welding, external plasma is used for single-pass bottoming welding without wire, and TIG and cold wire are used to fill the cover surface for the under-welded parts. The internal grinding wheel is used for grinding and cleaning, and the SAW multi-pass welding is used to fill the welding combination of the cover surface. The performance of the steel welded joint meets the welding process evaluation of pressure equipment NB/T 47014-2011 and stainless steel and heat-resistant steel for pressure equipment. The requirements of GB/T24511-2017 for steel plates and strips take advantage of the plasma + TIG welding method, which has the advantages of good weld quality, saving welding material costs, beautiful weld formation, high welding efficiency and SAW for easy internal welding and high weld bead quality. , which improves the problems of low welding efficiency, inconvenient inner wall welding, and limited welding thickness for large-diameter thick-walled cylinders above 8 mm by the plasma + TIG welding method.

(2) The positioning support of the inner wall of the cylinder is designed and used during the docking process of the cylinders of the present invention, and the two cylinders connected by the center are used for support, and the gap between the two cylinders is adjusted according to the pairing gap between the two cylinders read by the support sliding mechanism. The distance between the two cylinders is adjusted by adjusting the elongation of the arc plate to ensure that the alignment gap and the offset of the cylinder before welding meet the requirements of automatic welding, thus ensuring the plasma welding of large-diameter thick-walled cylinders. Adjust the angle of the threaded rod by moving the upper and lower sliders along the adjusting ring, and select a suitable support point to support the cylinder to ensure that the inner wall positioning support fits the cylinder; the cylinder supports the installation of threaded rods, guide rods, and limit blocks With the guide plate, the guide rod is adjusted by the threaded rod, so that the guide rod can be lengthened or shortened, so as to realize the support for the cylinders of different diameters and save the manufacturing cost; it is only necessary to rotate the rocker arm according to the scale on the guide rod of the support sliding mechanism. Move the left cylinder support to a suitable position to facilitate the installation of the left cylinder support; use the rotary handle and the nut to fix the cylinder support, and use bolts to stop the rotation of the rocker arm to fix the adjusted cylinder support position, thereby improving the performance of the cylinder. welding efficiency.

(3) The use of automatic plasma + TIG arc and automatic SAW instead of manual arc welding greatly improves the welding efficiency and the stability of the weld. There is a 5mm-thick blunt edge at the bottom of the groove surface, which realizes the welding of large-diameter thick-walled steel cylinders with a diameter of Φ1000-3000mm and a thickness of 8-25mm, which improves the labor intensity, welding operating environment and low utilization rate of welding materials. .

(4) The P+T+SAW welding method of the present invention can solve the problems of incomplete penetration, lack of fusion and difficulty in the pairing of large-diameter thick-walled cylinders with plasma+TIG welding of large-diameter thick-walled cylinders above 8 mm. The inner wall positioning support controls the pairing gap and misalignment between the two cylinders, so as to meet the high requirements of the cylinder assembly before plasma welding butt welding. Automatic plasma + TIG arc and automatic SAW welding are used to improve the large-diameter thick-walled cylinder. welding quality and efficiency.

(5) The present invention discloses a composite welding method suitable for a large-diameter thick-walled cylinder over 8 mm, which relates to the field of cylinder welding, in particular to a composite welding method for a large-diameter thick-walled cylinder, comprising the following steps: Large-diameter thick-walled cylinder over 8mm, the joint is a butt joint, with a reverse Y-shaped groove, the groove angle is 60°~70°, and the blunt edge is 5mm; the welding wire is selected according to the thickness and material of the weldment; the inner wall is equipped with a positioning support , adjust the distance between the two cylinders according to the paired gap between the two cylinders read by the support sliding mechanism, and use the cylinder support to adjust the amount of misalignment between the two cylinders, so that the weld gap and misalignment of the cylinder to be welded are The quantity meets the requirements of automatic welding; manual TIG is spot-welded on the outside for positioning; the external plasma of the cylinder is used for single-pass bottom welding without wire in the front, and the TIG is added with cold wire to fill the cover surface, the grinding wheel inside the cylinder is cleaned, and SAW is multi-pass. The welding combination method of multi-layer welding and filling cover, completes the plasma + TIG arc + SAW composite welding, the performance of the steel welded joint meets the welding process evaluation of pressure equipment NB/T 47014-2011 and stainless steel and heat-resistant pressure equipment Requirements for steel plates and strips GB/T 24511-2017. The invention is suitable for large-diameter thick-walled cylinders above 8 mm, has good welding seam quality, saves the cost of welding materials, beautiful welding seam formation, high welding efficiency, can improve the assembly quality of large-diameter thick-walled cylinders, and improves plasma + TIG welding above 8 mm The welding efficiency of large-diameter thick-walled cylinders is low, inconvenient for inner wall welding, and the welding thickness is limited.

Description of drawings:

Figure 1 is a schematic diagram of the welding groove

Figure 2 is a schematic diagram of the overall structure of the working state of the inner wall positioning support

Figure 3 is a schematic diagram of the cylinder support structure

Figure 4 is a schematic diagram of the structure of the support sliding mechanism

Figure 5 is a schematic diagram of the structure of the upper and lower sliders

In the figure: 1-cylinder support, 1a-right cylinder support, 1b-left cylinder support, 2-support sliding mechanism, 3-support disc, 4a-support rod, 5-adjustment ring, 6-upper Slider, 7-lower slider, 8-nut, 9-threaded rod, 4b-support rod, 10-guide plate, 11-guide rod, 12-limit block, 13-fixed block, 14-arc plate, 15-rotating handle, 16-fixing block, 17-lead screw, 18-guide rod, 19-rocker arm, 20-bolt, 21-fixing plate.

Detailed ways:

The present application will be described in detail below with reference to Figures 1-5 and in conjunction with the embodiments, and the present invention provides a technical solution:

Example 1:

A composite welding method suitable for large-diameter thick-walled cylinders over 8 mm.

This embodiment provides a hybrid welding method, including a plasma+TIG welding method and a SAW welding method. For a large-diameter thick-walled S30403 cylinder over 8 mm, the size of the cylinder is Φ2000 mm (diameter) × 20 mm (thickness). The system consists of the HCJ4030B circular seam P+T welding system jointly developed with the manufacturer and a special cross-arm submerged arc automatic welding machine.

The welded joint is a butt joint, with a reverse Y-shaped groove, the groove angle is 70°, and the blunt edge is 5mm; according to the welded cylinder, the filler material for TIG welding is ER308L wire with a diameter of Φ1.2mm, and the filler material for SAW welding It is ER308 L welding wire with a diameter of Φ3.2mm or Φ4.0mm, and the flux is SJ601.

Clean up impurities such as oil stains and burrs within 20mm on both sides of the weld. Lift the two workpieces to be welded after grinding or cleaning to the precision adjustable roller frame, and place the workpieces against the anti-channeling wheel. Positioning supports are installed on the inner walls of the cylinders on both sides. By adjusting the positioning supports, the weld gap and misalignment of the workpiece to be welded are adjusted to less than 0.5mm, and the inner walls are rounded. The positioning support of the present invention includes two parts, a cylinder support (1) and a support sliding mechanism (2).

As shown in Figure 3, the cylinder support (1) consists of a support plate (3), a support plate (4a), an adjusting ring (5), an upper slider (6), a lower slider (7), a nut ( 8), threaded rod (9), support rod (4b), guide plate (10a), guide rod (11), limit block (12), fixed block (13), arc plate (14) and rotary handle ( 15) Composition. The support plate (3) is circular, and four pairs of support plates (4a) are evenly arranged on the edge of the support plate (3). The support plates (4a) are welded to connect the adjustment ring (5) and the support plate (3). for the cuboid. The upper and lower sliding blocks are respectively installed on both ends of the ring (5), and each lower sliding block (7) is machined with a thread which is matched with the upper sliding block (6) for passing through the adjusting ring (5) and the upper sliding block (6) Threaded connection. The number of upper and lower sliders is 4 pairs. The upper and lower sliders are arc-shaped blocks with holes that are in contact with the bottom surface of the adjustment ring (5) and are horizontally away from the bottom surface of the adjustment ring (5). The curvature of the upper and lower sliders is equal to the adjustment ring. (5), the upper and lower sliders can adjust the position along the adjusting ring (5). The support rod (4b) is fixedly connected to the upper slider (6) and the limit block (12). Each upper slider (6) and the limit block (12) are connected with two support rods (4b). The support rods (4b) ) is a solid cylinder. A threaded rod (9) is threadedly connected to the inner side of the upper and lower sliding blocks. The threaded rod (9) passes through the upper and lower sliding blocks to rotate and connect to the limit block (12) and is fixed by a nut (8). The number of the threaded rods (9) is 8, of which 4 are adjustable in angle, the rest are fixed, and the number of nuts (8) is the same as that of the threaded rods (9). Two guide rods (11) are slidably connected in the limit block (12), and the fixing block (13) is fixedly connected with the guide rod (11) and the arc-shaped plate (14), and one end of the arc-shaped plate (14) is processed with a fixed For the external thread matched with the block (13), the arc-shaped plate (14) is used to meet the support requirements of cylinders with different inner diameters.

As shown in FIG. 4 , the support sliding mechanism (2) is composed of a fixed block (16), a lead screw (17), a guide rod (18), a rocker arm (19), a bolt (20), and a fixed plate (21). . The lead screw (17) passes through the central holes of the two disc-shaped cylindrical supports respectively, and the lead screw (17) is threadedly connected with the left cylindrical support (1a) and is rotatably connected with the right cylindrical support (1b). , the center of the left cylinder support (1a) is provided with a threaded hole that cooperates with the lead screw (17). ) fixed connection. Four guide rods (18) are slidably connected in the two cylinder supports, and the guide rods (18) are fixedly connected with the fixing block (16) and the support plate (3) of the right cylinder support (1a). The lower end of the rocker arm (19) is connected with the fixing plate (21) by bolts (20) to prevent rotation, and the positions of the mounting bolts (20) of the rocker arm (19) and the fixing plate (21) are provided with suitable bolt holes. .

As shown in Figure 2, when in use, firstly move the two cylinder supports (1) and support sliding mechanism (2) that have been shrunk into the cylinder that has been preliminarily aligned, according to the roundness of the cylinder, along the right cylinder The adjusting ring (5) of the body support (1b) moves 4 pairs of upper and lower sliders, adjusts the angles of the threaded rods (9) at different positions, selects a suitable position to support the cylinder, and tightens the upper slider (6) to make the threaded rods (9). The position is fixed (9), according to the inner diameter of the welding cylinder, the rotating handle (15) is operated to drive the threaded rod (9) to rotate, so that the guide plate (10) moves outward, and the guide plate (10) and the threaded rod (9) The thread function adjusts the protruding length of the guide rod (11), so that the arc plate (14) is pressed against the inner wall of the cylinder, and the threaded rod (9) of the right cylinder support (1b) is fixed by tightening the nut (8). Rotate the rocker arm (19) to rotate the lead screw (17), the left cylinder support (1a) moves along the guide rod (18), and adjust the rocker arm (19) to make the left cylinder support (1a) arc The plate (14) can be placed on the left side of the docking gap, read the scale on the guide rod (18) to obtain the pairing gap between the two cylinders, and adjust the distance between the two cylinders so that the pairing gap between the cylinders meets the welding requirements. According to the scale on the guide rod (18), move the left cylinder support (1a) to the installation position by turning the rocker arm (19), tighten the bolt (20) to prevent the rocker arm (19) from rotating, and move the upper and lower sliders Adjust the angle of the threaded rod (9), adjust the elongation of the arc plate (14) by adjusting the rotating handle (15), thereby adjusting the amount of misalignment between the two cylinders, and tighten the nut (8) to fix the left cylinder Support (1a).

The threaded rods (9) are provided with eight groups, of which four groups can be set along the adjustment ring (5) by adjusting the angle through the upper and lower sliders, and the remaining four groups are surrounded by the upper slider (6) around the adjustment ring (5) The center and other included angles are fixed.

Install the back protection tooling or drag cover. During the welding process, the welding pool on the front of the weld and the inner and outer surfaces of the welding joint are filled with argon with a purity of 99.99% as the protective gas. The flow rate of argon is 10~15L/min. The gas supply time is 3s, and the argon gas continues to circulate for 15s after the arc is interrupted. The argon gas drag cover is close to the nozzle of the welding torch. The high temperature resistant cloth is attached around the drag cover to form a closed protective cavity with the cylinder. The groove position is connected to the outside. Air isolation. Use a drag cover with a width of 60mm and a length of 120mm;

Through manual TIG spot welding of the positioning cylinder directly on the outside, the general penetration depth is about 2mm, the welding current of intermittent spot welding is 100A, the length of the solder joint is about 5mm, the width of the solder joint is 3mm, the welding discontinuity is 100mm, and the transition between the head and tail should be ground. Into a gentle slope, polished smooth. There should be no cracks and other defects in the positioning spot welding, and the defects should be completely removed and the positioning spot welding should be carried out again.

Using the plasma arc in the front and the TIG arc in the back, the front welds are respectively subjected to non-wire bottom welding and cold wire filling cover welding. When welding, start the plasma arc first, and after about 10s, turn on the TIG arc for welding. When the plasma welding torch exceeds the arc starting point by 15-20mm, start the gradual arc extinguishing program, first turn off the plasma arc, and after 10s, the TIG welding gradually extinguishes arc.

Through the Huaheng intelligent welding control system, adjust the angles of the plasma and TIG welding torches, so that the two welding torches are aligned with the center of the welding seam, the central axis of the plasma welding torch is perpendicular to the tangent of the circumferential seam, and the TIG welding torch is normally vertical; adjust the distance between the plasma welding torch and the workpiece surface 10 ~ 15mm , The shrinkage of the tungsten electrode is 2.8mm; the distance between the TIG welding torch and the workpiece surface is adjusted to 20-30mm, and the distance between the tip of the TIG tungsten electrode and the workpiece surface is 10-15mm.

Set the process parameters of plasma welding as follows: welding voltage is 30V, welding current is 210A, welding speed is 185mm/min, welding ion gas flow is 5.5L/min, shielding gas flow is 20~25L/min, and polarity is DC positive connection ;

Set the process parameters of TIG welding as follows: welding voltage is 14V, welding current is 230A, welding speed is 160mm/min, wire feeding speed is 1200mm/min; TIG welding torch has swing, yaw speed is 1500mm/min, left swing distance is 2.3 mm, the right swing distance is 2.3mm, the left stop time is 0.2s, the right stop time is 0.2s, and the polarity of the welding power source is DC positive connection;

After the back of the weld is ground and cleaned with a stainless steel special grinding wheel, a special cross-arm submerged arc automatic welding machine is used to penetrate the machine head into the barrel for multi-layer multi-pass welding. The distance between the conductive nozzle of the welding gun and the workpiece is 32-40mm. The process parameters of submerged arc automatic welding are set as follows: when the wire diameter is Φ3.2mm, the welding current is 380-420A, the welding voltage is 28-32V, and the line energy is 12.77-20.16KJ/cm; when the wire diameter is Φ4.0mm, The welding current is 500~550A, the welding voltage is 30~36V, the line energy is 18.0~29.7KJ/cm, the polarity of the welding power source is DC reverse, and the welding speed is 400~500mm/min. Then complete the plasma+TIG arc+SAW composite welding according to the set parameters.

During the welding process, the operator can observe the welding seam formation in the molten pool at any time through the arc monitoring system. Especially when the amount of misalignment and the gap is large, it is necessary to adjust the distance between the welding torch nozzle and the welding seam through the control panel in time, adjust the welding current, Welding speed, wire feeding speed, etc., ensure that the tip of the welding wire on the automatic wire feeder walks along the center line of the reverse Y-shaped groove, so as to avoid the drift of the TIG arc and improve the welding seam forming condition.

After the welding is completed, take out the thick-walled cylinder from the welding machine, and cut the sample to carry out the mechanical performance test according to NB/T 47016-2011 for the mechanical property test of the welded specimen of the pressure equipment. /T47014-2011, Requirements for stainless steel and heat-resistant steel plates and strips for pressure equipment GB/T 24511-2017.

Example 2:

A composite welding method suitable for large-diameter thick-walled cylinders over 8 mm. The steps are basically the same as in Example 1, but S31603 stainless steel with a thickness of 14 mm is welded.

Comparative ratio:

Through the commonly used SMAW welding method, the S31603 stainless steel with a thickness of 12mm is welded with a hand-operated electrode to complete the operation.

Test Example 1:

Take the thick-walled S31603 stainless steel welded in Example 2 and the comparative example for tensile test detection: use a sawing machine to cut the test piece from the middle position of the S31603 stainless steel test plate welded in Example 2 and the comparative example, and use a microcomputer to control the electrical The hydraulic servo universal testing machine is used to carry out a tensile test on it, and it is found that the tensile strength of the welded joint in Example 2 is 616.5 MPa; the tensile strength of the welded joint in the comparative example is 609.5 MPa.

Test Example 2:

Take the thick-walled S31603 stainless steel welded in Example 2 and the comparative example to carry out impact test detection: use a sawing machine to cut the sample from the middle position of the S31603 stainless steel test plate welded in Example 2 and the comparative example, and then use a planer and a grinder to The cutting surface was ground and processed, and the V-shaped notch was processed in the weld seam and the heat-affected zone by the impact specimen notch hydraulic broaching machine, and the Charpy impact test was carried out by using the pendulum impact testing machine. After the test, Example 2 was obtained. The impact absorption energy of the Charpy V-notch position at the weld is 82.33MPa, and the impact absorption energy of the Charpy V-notch position at the heat-affected zone is 281.33MPa; in the comparative example, the Charpy V-notch position is at the weld seam. The impact absorption energy at the heat-affected zone is 34.33MPa, and the impact absorption energy at the Charpy V-notch position at the heat-affected zone is 70.67MPa.

From the test data of Example 2 and the comparative example, it can be seen that the welding method provided by the present invention can make the strength and notch resistance of the welded joint higher than the existing SMAW method, and improve the welding quality.

To sum up, the welding method combining the three methods of plasma, TIG and SAW of the present invention solves the problems of assembling large-diameter thick-walled cylinders above 8 mm and quality control of plasma+TIG welding.

Claims (6)

1. The utility model provides a hybrid welding method suitable for major diameter thick wall barrel more than 8mm which characterized in that: the hybrid welding method comprises plasma arc, TIG arc and SAW welding, and adopts a hybrid welding mode to butt joint grooves of a large-diameter thick-wall cylinder body with the diameter phi of 1000-3000 mm and the thickness of 8-25 mm; the method comprises the following steps:

a plasma and TIG welding device adopts a circumferential seam P and T welding system; the SAW welding device adopts a special cross arm submerged arc automatic welding machine, and the machine head is deeply inserted into the cylinder body for welding;

a) designing a composite welding groove of the large-diameter thick-wall cylinder according to the material and the wall thickness of a workpiece to be welded, and processing the groove into a reverse Y shape;

b) selecting the type of the welding wire, wherein the type of the welding wire is selected according to the thickness and the material of the barrel;

c) before welding, machining grooves on two sides of a welding seam of the cylinder body, cleaning impurities such as oil stains, burrs and the like in the two sides of the welding seam, and exposing the natural color of metal on the surface;

d) hoisting the cleaned workpiece to be welded to a roller frame, installing positioning supports on the inner walls of the cylinders at two sides, adjusting the distance between the two cylinders according to the assembly gap between the two cylinders read by the supporting sliding mechanism, adjusting the misalignment amount between the two cylinders by adjusting the cylinder supports to ensure that the welding seam gap and the misalignment amount of the workpiece to be welded meet the automatic welding requirement, fixing the positioning supports, and rounding the inner walls;

the positioning support consists of a cylinder support (1) and a support sliding mechanism (2):

the cylinder support comprises a support disc (3), a support plate (4a), an adjusting ring (5), an upper sliding block (6), a lower sliding block (7), a nut (8), a threaded rod (9), a support rod (4b), a guide plate (10), a guide rod (11), a limiting block (12), a fixing block (13), an arc plate (14) and a rotating handle (15), wherein the support disc (3) is circular, the adjusting ring (5) is arranged outside the support disc (3), the adjusting ring (5) is fixedly connected with the support disc (3) through the support plate (4a) in a welding way, 4 arc grooves are symmetrically formed in the periphery of the adjusting ring (5), an upper sliding block and a lower sliding block are arranged on two sides of the adjusting ring (5), the upper sliding block and the lower sliding block are rectangular blocks which are in contact with the arc shape of the bottom surface of the adjusting ring (5) and are far away from the horizontal hole of the bottom surface of the adjusting ring (5), and the lower sliding block (7) penetrates through the arc grooves to be in threaded connection with one end of the upper sliding block (6), the other end of the upper sliding block (6) is fixedly connected with a supporting rod (4b), the outside of the supporting rod (4b) is fixedly connected with a limiting block (12), a threaded rod (9) passes through the upper sliding block, the lower sliding block and the guide plate (10) to be rotatably connected with the limiting block (12), the lower end of the threaded rod is provided with a rotating handle (15), and is fixed by a nut (8), the threaded rod (9) can be provided with 8 groups, wherein 4 groups are connected with an adjusting ring (5) through an upper sliding block and a lower sliding block, the angle along the adjusting ring (5) is adjustable, the other 4 groups penetrate through the upper sliding block (6) and are arranged around the circle center of the adjusting circular ring (5) at equal included angles, the inner side of the limiting block (12) is connected with a guide rod (11) in a sliding mode, the tail end of the guide rod (11) is fixedly connected with a fixing block (13), and the upper end of the fixing block (13) is connected with an arc-shaped plate (14) in a threaded mode;

the supporting sliding mechanism (2) comprises a lead screw (17), the lead screw (17) penetrates through center holes of two cylinder supports arranged in a disc shape respectively, one end of the lead screw (17) is rotatably connected with a fixed block (16), the other end of the lead screw penetrates through a fixed disc (21) and is fixedly connected with a rocker arm (19), a bolt (20) is arranged at the lower end of the rocker arm (19) and used for stopping rotation, four guide rods (18) are connected in the two cylinder supports in a sliding mode, and the guide rods (18) are fixedly connected with the fixed block (16) and a supporting disc (3) of the right cylinder support (1 a); the uppermost guide rod (18) is provided with scale marks and scale numbers, and the minimum unit of the scale numbers is millimeter;

e) mounting a back protection tool or a dragging cover, wherein the form of the back protection tool or the dragging cover is determined according to the diameter and the wall thickness of the cylinder body, the width of the back protection tool or the dragging cover is generally 60-80 mm, the length of the back protection tool or the dragging cover is 100-120 mm, high-temperature-resistant cloth is pasted on the periphery of the dragging cover, a sealed protection cavity is formed with the cylinder body, the position of the groove is isolated from the outside air, the gas flow of an external protection cover is 10-15L/min, the inside and outside surfaces of a welding joint are filled with protection gas, the gas supply time is 3s in advance, and the gas circulation is continued for 15s after the arc is broken;

f) the cylinder is directly positioned at the outer side by manual TIG spot welding, the general penetration is about 2mm, the welding current is 100A, the length of a welding spot is about 5mm, the width of the welding spot is 3mm, the welding discontinuity is 100mm, the transition part between the head and the tail is polished into a smooth and gentle slope shape, and if cracks and other defects exist, the cylinder is thoroughly ground to be re-spot-welded;

g) setting welding process parameters before welding arcing;

the parameters of the automatic plasma welding process are set as follows: the central axis of the plasma welding gun is perpendicular to the tangent line of the circular seam, the distance between a conductive nozzle of the welding gun and a workpiece ranges from 10 mm to 15mm, the tungsten electrode contracts inwards by 2.8mm, the plasma welding gun does not swing, the ionic gas flow is 5L/min to 6L/min, the protective gas flow is 20L/min to 25L/min, the welding voltage is 29V to 31V, the welding current is 240A to 260A, the polarity of a welding power supply is direct current direct connection, and the welding speed ranges from 150 mm/min to 200 mm/min;

the parameters of the automatic TIG welding process are set as follows: the TIG welding gun is normal and vertical, the distance between a conductive nozzle of the welding gun and a workpiece ranges from 20mm to 30mm, the distance between a tungsten electrode and the workpiece ranges from 10 mm to 15mm, the TIG welding gun has swing, the yaw speed is 1500mm/min, the left swing distance is 2.3mm, the right swing distance is 2.3mm, the left stop time is 0.2s, and the right stop time is 0.2 s; the welding voltage is 17-19V, the welding current is 230-250A, the wire feeding speed is 1200-1500 mm/min, the polarity of a welding power supply is direct current positive connection, and the welding speed range is 160-200 mm/min;

the automatic SAW welding process parameters are set as follows: the distance between a conductive nozzle of a welding gun and a workpiece ranges from 32 mm to 40mm, the diameter of the SAW welding wire is selected according to the thickness of a cylinder, when the thickness of the cylinder is less than 12mm, the diameter of the welding wire is phi 3.2mm, the welding current is 380-420A, the welding voltage is 28-32V, and the linear energy is 12.77-20.16 KJ/cm; when the thickness of the cylinder body exceeds 12mm, the diameter of a welding wire is phi 4.0mm, the welding current is 500-550A, the welding voltage is 30-36V, the linear energy is 18.0-29.7 KJ/cm, the polarity of a welding power supply is direct current reverse connection, and the welding speed range is 400-500 mm/min;

h) when welding, the protective gas is communicated 3s in advance, plasma arc is adopted to weld the blunt edge on the front side of the weld seam without adding wires to perform backing welding, and TIG electric arc is used to add cold wires to fill the cover surface on the incomplete welding part; the back groove of the welding seam is firstly polished to have metallic luster by using a stainless steel special grinding wheel, then SAW is used for multi-layer and multi-pass welding, the temperature between layers is controlled to be not more than 150 ℃, considering that a skull is easy to fall off, the welding seam and impurities on two sides of the welding seam are not required to be polished by using a stainless steel wire brush after each layer of welding is finished, and whether polishing is carried out can be determined according to the fusion and forming conditions of the welding seam; during welding, starting a plasma arc, starting a TIG electric arc for welding after about 10s, starting a progressive arc quenching program when a plasma welding gun is welded and exceeds an arc striking point by 15-20 mm, and stopping the plasma arc firstly and stopping the TIG welding progressively after 10 s;

i) and cleaning the welded seam until the surface has metallic luster.

2. The hybrid welding method suitable for the large-diameter thick-wall cylinder with the diameter of more than 8mm according to claim 1, characterized in that: the material of the workpiece to be welded in the step (a) is stainless steel.

3. The hybrid welding method suitable for the large-diameter thick-wall cylinder with the diameter of more than 8mm according to claim 1, characterized in that: the inverted Y-shaped groove in the step (a) has a truncated edge thickness of 5mm and a groove angle controlled at 60-70 degrees.

4. The hybrid welding method suitable for the large-diameter thick-wall cylinder with the diameter of more than 8mm in the claim 1, wherein the shielding gas in the steps (e), (h) and (g) is 99.99% argon or 95% argon + 5% hydrogen with purity; and (h) performing automatic start-stop control on the plasma arc and the TIG electric arc, wherein the start and stop of the TIG electric arc are lagged by the plasma arc for 10 s.

5. The hybrid welding method suitable for the large-diameter thick-wall cylinder with the diameter of more than 8mm according to claim 1, characterized in that: and (d) the welding seam gap and the misalignment of the workpieces to be welded in the step (d) are not more than 0.5 mm.

6. The hybrid welding method suitable for the large-diameter thick-wall cylinder with the diameter of more than 8mm according to claim 1, characterized in that: and (d) arranging bolt holes matched with the positions of the rocker arm (18) and the mounting bolt (20) of the fixed disc (21) in the step (d).

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