RU2492038C1 - Method of welding large-sized metallic shells - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to oil and oil-refining industries and may be used in development of oil processing equipment, particularly, in assembly of large-sized metallic tanks, say, separators, settlers, oil storage tanks, etc. Proposed method comprises butt hidden-arc welding of metal sheets with forced feed of flux from above and below of weld seam. Then cylinders are rolled from welded sheets. Then butt is welded long the cylinders with forced feed of melt from above and below of weld seam to produce cylindrical shell. Cylindrical shells are arranged at rolls to make their end surfaces face each other. Butt hidden-arc welding of cylindrical shells is carried out with forced feed of flux from above and below of weld seam. Note here that arc zone is filled with the melt between the shells by feeding the melt from inside of shells. In welding the shells are rotated.

EFFECT: higher strength and quality of weld seam.

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Description

The invention relates to the oil and oil refining industry and may find application in the manufacture of equipment for oil refining, in particular in the assembly of large-sized metal tanks such as separators, sumps, tanks for storage and preparation of oil.

A known method of mounting the drum of the boiler by moving through the rollers and installing the drum on the support of the upper platform of the boiler frame. The drum is mounted on rollers with prefabricated parts and assembled on the upper platform of the boiler frame by welding the shells of the drum parts and subsequent heat treatment of the seams. In this case, the welding of the shells of the drum sections is performed under the submerged arc in a multilayer manner, in sections with a shift in the places of the beginning and end of the weld section in subsequent layers by rotating the drum sections during rotational movement of the rollers. Heat treatment of welds in the zones of welding shells is carried out using convective or inductive heaters, or using steam from an adjacent boiler. The technical result of the invention is to increase the manufacturability of installation and reduce the complexity of replacing the drum of the boiler (RF Patent No. 2359168, published. 06/20/2009).

Closest to the proposed invention is a method of manufacturing a large-sized metal shell, consisting of at least two metal shells, including butt welding of metal sheets under flux with forced flux supply from above and below the weld, rolling of cylinders from them, welding of the joint along cylinders with forced supply of flux from above and below the weld, with the receipt of cylindrical shells, the placement of the cylindrical shells on the rollers with the end surfaces to each other and welding and x butt on the ends of the cylindrical shells. The quality of the finished product is improved (Kurkin S.L. et al. Technology, mechanization and automation of production of welded structures, M., "Mechanical Engineering", 1989, pp. 40-41, pp. 60-61, Fig. 5, 6, 9 , p.183-186, 221 fig. 6 - prototype).

The proposed invention solves the problem of increasing the strength of welded shells by improving the quality of welds.

The problem is solved by a method of manufacturing large-sized metal shells, including butt welding of butt-welded metal sheets with forced flux supply from above and below the weld, from welded metal sheets to rolling the cylinder, butt welding of metal sheets along the cylinder with the formation of a cylindrical shell with forced flux supply from above and below the welded weld, placement of cylindrical shells on rollers with end surfaces facing each other, butt welding along the ends of cylindrical shells with the same by rotating the two shells with forced flux supply from above and below the weld, when butt welding, to force flux from the bottom of the weld, a bath with a flexible bottom filled with a flux is placed under the weld and the flexible bottom and volume of the flux are pressed from the bottom to the weld Butt welding on the ends of cylindrical shells for forced flux supply from the bottom of the weld under the weld place a bowl-shaped container with elastic sides that can rotate freely on the axis, with an axis on the hinge and with the possibility of move vertically, place a bowl-shaped container under the shells in the zone of the weld with the inclination of the axis of the bowl to the vertical at an angle of 10-15 degrees. and by contacting the sides of the cup-shaped container with the bottom of one of the shells, fill the cup-shaped container with a welding flux and replenish the flux when it is consumed, fill the welding zone between the shells from the inside of the shells, rotate the shells with the transmission of rotation of the cup-shaped container.

SUMMARY OF THE INVENTION

In the manufacture of large, i.e. more than 1 m in diameter, metal shells pay special attention to the quality of welds. Butt welding of metal sheets is carried out end-to-end with a small gap between the sheets. With submerged arc welding, it is not particularly difficult to supply the flux from above to the welding zone. But at the same time, flux spills between the metal sheets and exposes the weld. As a result, the weld is weakened, lack of fusion, burn-through of the base metal take place. The use of a flux bath under the weld also does not solve this problem, because the flux in the bath settles and the weld zone remains without a flux. The flux consumption for welding also leads to the same effect. Existing technical solutions either do not solve this problem or solve it only partially. The proposed invention solves the problem of increasing the strength of welded shells by improving the quality of welds. The problem is solved as follows.

When welding large-sized metal shells, electric welding of metal sheets is carried out end-to-end under the flux with forced flux supply from above and below the weld. Cylinders are rolled from welded metal sheets by bending sheets into cylinders on a three-roll plate bending machine. Along the cylinder, the metal sheets are butt-welded to form a cylindrical shell. Electric welding is carried out in a semi-automatic mode with forced supply of flux from above and below the weld. The resulting cylinders are placed on rollers with end surfaces facing each other. They perform electric welding butt-to-butt on the ends of cylindrical shells with simultaneous rotation of two shells with forced supply of flux from above and below the weld, after welding, a large-sized metal shell is obtained. If necessary, one or two bottoms are welded to the shell, or a transition, or some other extension, depending on the specific application in the workplace.

When welding metal sheets end-to-end for forced flux supply from the bottom of the weld, a bath with a flexible bottom filled with a flux is placed under the weld. Figure 1 shows a bath with a flux with a system of preloading the flux to the weld. Under the metal sheets 1 there is a bath 2 with a rubber bottom 3, under which there is an asbestos gasket 4 and hoses 5 of the type of firefighters, capable of inflating and increasing in diameter, which contributes to the tight fit of the flux from the bottom of the welded joint. The flux 6 is placed under the metal sheets 1 above the rubber bottom 3.

When welding, compressed air is supplied through the sleeves 5, which increase in diameter and press the rubber bottom 3 and flux 6 to the metal sheets 1, ensuring the presence of flux 6 in the welding zone between the sheets 1. Asbestos gasket 4 protects the sleeves 5 from the effects of the elevated temperature that occurs when welding.

The same bath is used for butt welding of metal sheets molded into a cylindrical shape. Along the cylinder, the metal sheets are butt-welded to form a cylindrical shell.

When welding end-to-end at the ends of cylindrical shells for forced flux supply from the bottom of the weld in the welding zone, the equipment shown in Fig. 2 is placed.

In figure 2, the bowl-shaped container 7 with elastic sides 8 made of rubber is filled with a flux 6. The container 7 is mounted on the axis 9 and can rotate freely on the axis 9. The axis 9 is mounted on the hinge 10. The container 7 is located under the shells 11 with an offset of the axis 9 relative to the zone welding (weld) 12 along the metal shells 11 at an angle α. The shells are mounted on roller bearings 13 with the possibility of rotation on the roller bearings 13. Inside the shells there is a hopper for supplying flux 14 with a flux 15 and a welding head 16 on the console 17. The axis 9 is mounted through a hinge 10 on the pneumatic cylinder 18 with the possibility of vertical movement under the action of the pneumatic cylinder 18 .

The operation of the device.

The cup-shaped container 7 is placed under the shells 11. The pneumatic cylinder 18 presses the cup-shaped container 7 against the weld 12 of the shells 11, which contributes to the snug fit of the flux 6 from the bottom to the weld 12 between the shells 11. In the welding zone 12, the axis 9 is displaced along the weld 12 along the metal shell 11. For this, the bowl-shaped container 7 is placed with the axis 9 inclined towards the offset at an angle α = 10-15 degrees to the vertical and the elastic side 8 of the bowl-shaped container 7 is contacted with the bottom of one of the shells 11.

The cup-shaped container 7 is filled with a flux 6. During electric welding, the welding head 16 is sent to the welding zone 12 inside the shells 11, also inside the shells 11, the flux 15 is fed from the hopper 14. From below the shells 11, the flux 6 is fed into the welding zone 12 from the cup-shaped tank 7. When the shells 11 rotate by contacting the elastic side 8 of the bowl-shaped container 7 with the shell 11, the rotation is transmitted from the shell 11 to the bowl-shaped container 7 which is inclined and touching the shell 11. The elastic side 8 of the bowl-shaped vessel 7 is unbent and the flux 6 touches the s welding 12. On the other side of the cup-shaped container 7 separated from the sleeve 11, pour flux 6, providing replenishment flux 6 by its expenditure. Butt weld at the ends of the shells 11.

The result is high-quality welds.

Concrete example

A large-sized metal shell is made with a diameter of 2000 mm, a length of 4000 mm and a wall thickness of 20 mm. Electric welding is carried out in semi-automatic mode using a welding wire brand SV-08GA with an electric current voltage of 38-40 volts and a current strength of 700-750 amperes.

They perform electric welding of metal sheets with a thickness of 20 mm end-to-end under an AN-47 grade flux. In electric welding, a forced flux is supplied from above and below the weld. At the top of the weld, fluxing is performed, and a fixture is used to supply the flux from below and the work of the device shown in Fig. 1 is performed. Get sheets with dimensions of 6280 × 2000 mm each.

From welded metal sheets, cylinders are formed by bending sheets into cylinders on a three-roll plate bending machine. Get 2 cylinders with an outer diameter of 2000 mm and a length of 4000 mm. Along each cylinder, butt welding of metal sheets is carried out with the formation of a cylindrical shell.

The resulting shells are placed on rollers with end surfaces facing each other. Butt welding is performed at the ends of the cylindrical shells with the simultaneous rotation of two shells with the forced supply of flux from above and below the weld. In electric welding, a forced flux is supplied from above and below the weld. At the top of the weld, fluxing is carried out, and a fixture is used to supply the flux from below and the work of the device shown in Fig. 2 is performed.

After welding, a large-sized metal shell with high-quality welds is obtained. At the seams there is no thickness variation, lack of fusion, burn-through.

The application of the proposed method will increase the strength of the welded shells by improving the quality of welds.

Claims (1)

A method of manufacturing a large-sized metal shell, consisting of at least two metal shells, including butt welding of submerged metal sheets with forced flux supply from above and below the weld, rolling of cylinders from them, joint welding along cylinders with forced flux supply from above and below weld, with obtaining cylindrical shells, placing cylindrical shells on rollers with end surfaces facing each other and butt welding them at the ends of cylindrical shells, characterized the fact that when welding butt-metal sheets, the forced supply of flux from the bottom of the weld is ensured by placing a bath made with a flexible bottom and filled with a flux under the weld, and pressing its flexible bottom with a flux from the bottom to the weld, butt welding at the ends of the cylindrical shells forced supply of flux from above and below the weld, and forced supply of flux from the bottom of the weld is provided by placing a bowl-shaped container with elastic sides under the weld, with the possibility of contraction activating the sides of the cup-shaped container with the bottom of one of the shells, and the cup-shaped container is fixed on the axis with rotation, which is pivotally mounted on the pneumatic cylinder with the ability to move vertically and tilt the axis of the bowl to the vertical at an angle of 10-15 °, while the cup is filled with a welding flux in the welding process, fill the flux welding zone between the shells by supplying flux from the inside of the shells, welding is performed with the rotation of the welded shells.

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