RU2562200C1 - Method of manufacturing of axisymmetric welded pressure shells - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: shell pipe blanks are made out of structural alloyed steels for cold-forming. The shell blanks are subjected to the strain hardening by the rotating drawing by several transitions. At the last transition the shell blanks are subjected to the thermal strain hardening by quenching with tempering with the blank heat fixing on the expanding mandrel, grit blasting of the external and internal surfaces, rotating drawing and annealing. The lathe turning is performed with formation of the welded edges. The shell and rings is assembled on the expanding mandrel with removable shim with butt joint clearance 0.15÷0.2 of thickness of the welded edges with fit-up of the butt edges by means of diametrical tension within range of the elastic deformations by value (0.1÷0.15)% of actual length of the edge circle. Automatic welding is made with consumable electrode by single pass with through penetration of the welded edges. The low temperature tempering and X-ray testing of the welds are performed the welded rings are machined with production of the buttress thread, the shell is hydraulically and pneumatically tested.

EFFECT: method ensures high mechanical properties of the axisymmetric welded shells at low residual internal stresses, high accuracy of geometrical dimensions.

2 cl, 5 dwg, 1 ex

Description

The invention relates to the processing of metals by pressure and welding, and in particular to the manufacture of welded axisymmetric shells, which are cylindrical thin-walled shells with cylindrical thickened rings welded at the ends, and intended for welded vessels operating under high pressure, vessels for compressed air, liquefied and dissolved gases and used in various economic fields in the manufacture of fire extinguishers, oxygen and gas cylinders, compressed air cylinders, liners, receiver s, etc.

The main requirements for pressure-welded shells are as follows: high structural and cyclic strength, geometric accuracy, surface finish, high quality welded joints, high manufacturing capacity and low weight.

A known method of manufacturing axisymmetric housings operating under pressure, RF patent No. 2295416, B21D 51/24, publ. 03/20/2007, Bull. No. 8, which describes a method for the production of axisymmetric housings with end thickenings.

The method includes hardening, tempering, cold plastic deformation by rotational drawing in two passes, low-temperature annealing. Use alloy steel.

The main disadvantage of the above method for the manufacture of pressurized housings is the high complexity and cost of manufacture due to the shaping by pressure treatment of all-metal pipe blanks with end thickenings without welded joints.

The closest in technical essence and the achieved technical result is a method of manufacturing high-strength axisymmetric shells operating under high pressure (Novikov OM et al. "New technology for arc welding in protective gas of high-pressure cylinders" magazine "Professional welder" No. 1, 2005, p. 14-45), adopted by the authors for the prototype, in which the machined part blanks are assembled using an assembly-welding fixture and the joints are welded with one-side mechanized electric arc welding n with a melting tungsten electrode in two passes with filler wire in the second pass, with argon blowing from the inside from the root side of the seam, with alternating discrete (pulsating) supply of two protective gases - argon and helium to the zone of the continuously burning arc with simultaneous control of the arc voltage, then the final voltage is controlled machining, hardening heat treatment, control and testing of welds.

This method requires expensive helium, a complex system for regulating the supply of two protective gases and controlling their consumption, controlling the pulsation of separate flows of protective gases in the optimal frequency range. In addition, there is no strict system for fixing joints in welding. Welding is carried out on weight.

The reasons that impede the achievement of the technical result indicated below when using the known method of manufacturing axisymmetric welded shells, adopted by the authors as a prototype, include the inability to provide high dimensional accuracy in alignment, as well as end and radial runout.

According to the applicants, the reason for the low accuracy in alignment, in the end and radial runout of the connected parts of the shells is the lack of solutions for fixing abutting edges during assembly and welding.

In addition, in this method, adopted by the authors for the prototype, there are no methods for the preparation and rotational processing of blanks of the shell and rings and their thermo-deformation and thermal hardening before welding.

The disadvantage of the prototype is also the hardening of the shells after welding, which leads to a change in geometric dimensions due to thermal influences.

Thus, the objective of this technical solution adopted for the prototype was to improve the quality of the welded joint and reduce the complexity of manufacturing.

Common features with the proposed by the applicants method of manufacturing axisymmetric welded shells operating under high pressure, containing a thin-walled shell with welded thickened rings, is the machining of the blanks of the shell and rings, their assembly in the fixture, electric arc welding on one side in protective gases, final machining, control and weld tests.

In contrast to the prototype, the method proposed by the applicants for the manufacture of axisymmetric welded shells operating under high pressure is based on the fact that the pipe blanks of the shell made of structural complex alloyed steels for cold deformation are first subjected to strain hardening by a rotational hood for several transitions, and at the last transition, the workpieces are subjected to thermal deformation hardening in the form of hardening with tempering with heat setting of the workpiece on a sliding mandrel, shot peening and the inner surface, rotational drawing and annealing, reducing stress, the rotation drawing is performed by deforming rollers with a front angle of one of the rollers less than 1.5 ÷ 2.5 times the front angles of the subsequent rollers and installed in the same plane of the cross section with a radial shift with the same clearances with the mandrel of the subsequent rollers, then the turning of the shell and rings with the formation of welded edges is performed, the assembly and welding of the shell and rings on an expanding mandrel with on a removable lining with a gap in the joint equal to 0.15 ÷ 0.2 of the thickness of the welded edges, with a combination of the joint of the edges by means of diametrical stretching within elastic deformations by (0.1 ÷ 0.15)% of the actual edge circumference, automatic welding the assembled parts with a consumable electrode in one pass with through penetration of the welded edges, then low-temperature tempering and X-ray television monitoring of welds, turning of welded rings to obtain threaded threads, hydraulic and pneumatic ytaniya shell.

In the particular case, that is, in a specific form of execution, the invention is characterized by the following feature:

- billet rings before welding is subjected to hardening and tempering to the tensile strength of the material, comprising 0.6 ÷ 0.8 tensile strength of the material of the shell.

This is what allows us to conclude that there is a causal relationship between the totality of the essential features of the claimed technical solution and the achieved technical result.

These signs, distinctive from the prototype and to which the requested amount of legal protection applies, are sufficient in all cases.

The objective of the invention is to provide high mechanical strength, ductility, high toughness and low level of residual internal stresses, geometric accuracy and manufacturability of axisymmetric welded shells, welded joints, operational reliability and high cyclic strength with low weight and low complexity.

The specified technical result in the implementation of the invention is achieved by the fact that with the known method of manufacturing axisymmetric shells operating under high pressure, containing a thin-walled shell with welded thickened rings, including machining of the shell blanks and rings, assembling them in the device, one-sided arc welding in protective gases , the final machining, control and testing of welds, the feature is that the pipe blanks of the shell of complex structurally alloyed steels for cold deformation are first subjected to strain hardening by rotational drawing in several transitions, and at the last transition of the workpiece, they are subjected to thermal deformation hardening in the form of quenching with tempering with heat setting of the workpiece on a sliding mandrel, shot peening of the external and internal surfaces, rotational drawing stress and , the rotation hood is performed by deforming rollers with a front angle of one of the rollers less than 1.5 ÷ 2.5 r the values of the front angles of the subsequent rollers and installed in the same plane of the cross section with a radial displacement at equal gaps with the mandrel of the subsequent rollers, then turn the shell and rings to form welded edges, alternate assembly and welding of the shell and rings on an expandable mandrel with a removable a lining with a gap in the joint equal to 0.15 ÷ 0.2 of the thickness of the welded edges, with a combination of the joint of the edges by means of diametrical stretching within elastic deformations by (0.1 ÷ 0.15)% of the actual circumference of the edges, automatic welding of the assembled parts with a consumable electrode in one pass with through-penetration of the welded edges, then low-temperature tempering and X-ray inspection of the welds, turning of the welded rings to obtain threaded threads, hydraulic and pneumatic shell tests.

The new set of operations, as well as the presence of relations between them, allow, in particular, due to:

- the use of pipe blanks of shells made of structural complex alloyed steels for cold deformation (22KH3GN2M1FA TU 1308-005-33116077-2001, etc.) to increase the utilization of metal and provide the possibility of thermal deformation hardening of pipe blanks and, as a result, to obtain shells with high mechanical properties (high mechanical strength and ductility) at a low level of internal residual stresses, high impact strength and cyclic strength;

- strain hardening shell blanks with a rotary hood for several transitions, to obtain the necessary mechanical properties and dimensions of the blanks for subsequent processing;

at the last transition of thermodeformational hardening of the shell blanks in the form of hardening with tempering with heat setting of the blank on a sliding mandrel, shot peening of the outer and inner surfaces, rotational drawing and annealing, reducing stress, to ensure optimal values of mechanical properties: tensile strength, elongation, impact strength at low level of residual internal stresses, since when performing thermal deformation hardening at the first, second and subsequent moves, according to the results of experimental work, there is an increase in power loads due to an increase in the metal hardening along transitions, the service life of the rollers is reduced and breakdowns of the units of the press-rolling machines occur, in addition, quenching with tempering with heat setting of the workpiece on a sliding mandrel ensures the accuracy of geometric parameters, the ovality of the diametrical dimensions and the curvature of the generatrix are reduced;

- bead-blasting of the outer and inner surfaces of the shell blanks during thermo-deformation hardening reduce the level of residual internal stresses, since when shot blasting hardens the surface layers of the metal blanks and internal stresses take on the character of compressive all-round stresses, and after rotational drawing, internal tensile stresses radial and tangential , as a result of the total residual internal stresses after shot peening, company exhaustion and annealing, which reduces stresses, decrease, and, according to the results of experimental work, the level of residual internal stresses does not exceed 20% of the yield strength of the material, which is a sufficient condition for reliable operation of the shells;

- rotational drawing by deforming rollers with a front angle of one of the rollers that is 1.5–2.5 times smaller than the front angles of the subsequent rollers and installed in the same plane of the cross section with radial displacement at equal gaps with the mandrel of the subsequent rollers to increase the stability of the deformation process and, therefore, the accuracy of geometric dimensions in the manufacture of shells of complex alloyed steels, since the deformation of alloy steels of this class requires high efforts machining, especially the radial and axial forces of the rotary hood, so this arrangement of the rollers allows to reduce the deformation forces, firstly, when all the rollers are in the same plane of the cross section along the tops of the roller profiles, the axial forces are reduced, and secondly, the execution of one of the rollers with the front at an angle smaller by 1.5–2.5 times the values of the front angles of the subsequent rollers with a shift in the radial direction with the same gaps with the mandrel of the subsequent rollers, the radial forces are reduced, since e rollers share the deformation between the rollers, that is, a roller with a smaller rake angle deforms first, with one degree of deformation, and subsequent rollers with a different degree of deformation, while the deformation centers are also offset from each other, which ensures the sequence of work of the rollers both in axial and and in the radial direction, such a roller displacement scheme ensures smooth growth of deformations along the metal flow lines along the forming mandrel, the stability of the rotational drawing process increases, improving the quality of the machined surface and the accuracy of the geometric shape, the values of the rake angles, according to the results of experimental work, are optimal, with an increase or decrease in this ratio, the stability of the rotational drawing process is violated, when the rake angle of one of the rollers is less than 1.5 times, metal shrinkage occurs rollers, with more than 2.5 times corrugations appear in the form of convex-concave waves of the metal, the equalities also contribute to a decrease in the deformation forces and increase the stability of the rotational drawing process then the clearance of subsequent rollers with a mandrel, the applicants explain the factor of reducing the deformation forces when the gap is equal to the fact that the total degree of deformation is reduced and the quality of the processed surface is improved, since subsequent rollers move along the same paths with the same degree of deformation;

- turning the shell and rings with the formation of the welded edges to provide the necessary geometric shape and dimensions of the joint for welding;

- alternate assembly and welding of the shell and rings on an expandable mandrel with a removable lining with a gap in the joint equal to 0.15 ÷ 0.2 of the thickness of the welded edges, to increase the manufacturability and productivity of assembly and welding operations, to ensure penetration of the weld root and the entire cross section of the welded joint;

- combining abutting edges by means of diametrical extension within elastic deformations by (0.1 ÷ 0.15)% of the actual circumference, to ensure a tight joint of the edges to be welded without mutual displacement and thereby increase the geometric accuracy of the welded shell;

- automatic welding of assembled parts with a consumable electrode in one pass with through-penetration of the welded edges, to increase the productivity and manufacturability of welding, to reduce the influence of the human factor on the process of obtaining high-quality welded joints;

- low-temperature tempering of welds to reduce the level of residual stresses and prevent the formation of cold cracks in the weld zone while maintaining the high mechanical properties of the hardened material of the shell and ring;

- X-ray television inspection to identify internal defects in the weld metal and near-weld zones (lack of penetration, pores, cracks, slag inclusions) with automatic recording of the inspection results on the defectogram and decoding the type of defect, its length and location at the seams;

- turning the welded rings to obtain threaded threads to provide the ability to connect welded shells with mating parts;

- conducting hydraulic and pneumatic tests to guarantee the necessary strength and tightness of welded joints and the entire shell.

A sign that characterizes the proposed technical solution in a specific form of execution allows, in particular, due to:

- hardening and tempering of ring blanks before welding to a material tensile strength of 0.6 ÷ 0.8 of the shell material tensile strength to provide the necessary structural strength of the thickened rings in the shell and the possibility of cutting resistant threads into them.

Signs that distinguish the proposed technical solution from the prototype are not identified in other technical solutions and are not known from the prior art in the process of conducting patent research, which allows us to conclude that the invention meets the criterion of "novelty."

Studying the level of technology during the patent search for all types of information available in the countries of the former USSR and foreign countries, it was found that the proposed technical solution does not explicitly follow from the prior art, therefore, we can conclude that the criterion of "inventive step" ".

The essence of the invention lies in the fact that in the method of manufacturing axisymmetric welded shells operating under high pressure, containing a thin-walled shell with welded thickened rings, including machining the blanks of the shell and rings, assembling them in a fixture, one-sided arc welding in a protective gas environment, final mechanical processing, control and testing of welds, in contrast to the prototype, according to the invention, pipe blanks of a shell from structural complex steel steels for cold deformation are first subjected to strain hardening by rotational drawing for several transitions, and at the last transition, the workpieces are subjected to thermal deformation hardening in the form of tempering with heat setting of the workpiece on a sliding mandrel, shot peening of the outer and inner surfaces, rotational drawing and annealing, reducing stress rotation hood is performed by deforming rollers with a front angle of one of the rollers less than 1.5 ÷ 2.5 times the values of the front angles of the last blowing rollers and installed in the same plane of the cross section with a radial displacement at equal gaps with the mandrel of the subsequent rollers, then they perform turning of the shell and rings with the formation of welded edges, sequential assembly and welding of the shell and rings on an expandable mandrel with a removable lining with a gap in the joint equal to 0.15 ÷ 0.2 of the thickness of the welded edges, with the combination of the joint of the edges by means of diametrical stretching within elastic deformations by (0.1 ÷ 0.15)% of the actual length of the edge NOSTA edges automatic welding consumable electrode assembled parts in one run with a through-penetration welded edges, and then low temperature tempering, and X-ray inspection of welds, welded rings turning operation to obtain a buttress thread, hydraulic and pneumatic test membrane.

The invention is illustrated by drawings, where in FIG. 1 - a process of rotational drawing of a blank of a shell 1 by deforming rollers 3, 4 and 5 on a mandrel 6, in FIG. 2 - shell 1 with heat setting along the inner surface on a sliding mandrel, in FIG. 3, a shell 1 joined and welded to a ring 2 on an expandable mandrel, in FIG. 4 is a view I of FIG. 3 enlarged view of the joint zone and the weld of the shell 1 with the ring 2, in FIG. 5 shows an axisymmetric shell containing a thin-walled shell 1 with thickened rings 2 welded to it.

, который деформирует заготовку обечайки 1 с зазором Δ₃ (мм) между вершиной профиля ролика и оправкой 6, ролики 4 и 5 деформируют заготовку обечайки с зазором Δ₄ и Δ₅, при этом Δ₄ (мм)=Δ₅ (мм), $${\alpha }_4^{°}={\alpha }_5^{°}$$

и $${\alpha }_3^{°}<{\alpha }_4^{°}={\alpha }_5^{°}$$

, n (мин^-1) - скорость вращения, F (мм/мин) - направление осевой подачи роликов 3, 4 и 5, t₀ (мм) - толщина стенки исходной заготовки, t (мм) - толщина стенки заготовки обечайки после деформирования, С (мм) - смещение роликов.In FIG. 1 shows a roller 3 with a rake angle $${\alpha }_3^{°}$$

which deforms the blank of the shell 1 with a gap Δ ₃ (mm) between the top of the profile of the roller and the mandrel 6, the rollers 4 and 5 deform the blank of the shell with a gap of Δ ₄ and Δ ₅ , with Δ ₄ (mm) = Δ ₅ (mm), $${\alpha }_{\mathrm{four}}^{°}={\alpha }_5^{°}$$

and $${\alpha }_3^{°}<{\alpha }_{\mathrm{four}}^{°}={\alpha }_5^{°}$$

, n (min ^-1 ) is the rotation speed, F (mm / min) is the direction of the axial feed of the rollers 3, 4 and 5, t ₀ (mm) is the wall thickness of the initial workpiece, t (mm) is the wall thickness of the shell blank after deformation , C (mm) is the displacement of the rollers.

In FIG. 2 shows a sliding mandrel for thermofixing a blank of a shell 1, which consists of a housing 17, a rod 18, sliding sectors 19, a nut 16, a spring 15, sulfur 13, a support 14, a rod of a hydraulic cylinder 20 and fasteners.

In FIG. 3, the expanding mandrel contains sectors 7 with an inner conical surface and a removable lining 12, an abutment 8 with an outer conical surface, a rod 9, a stop flange 10, and an earring 11.

In FIG. 4 shows: a removable lining 12, sector 7, t _article (mm) is the thickness of the edges to be welded, b (mm) is the gap at the joint of the edges to be welded.

The above method of manufacturing thin-walled welded shells is as follows.

в 1,5÷2,5 раза меньшим значения передних углов последующих роликов 4 и 5, ролики 3, 4 и 5 установлены в одной плоскости поперечного сечения по вершинам профилей со смещением в радиальном направлении С (мм) (фиг.1) с зазорами между вершинами и оправкой 6 ролика 3 - Δ₃ (мм), ролика 4 - Δ₄ (мм) и ролика 5 - Δ₅ (мм), ролики 4 и 5 установленные с одинаковыми зазорами Δ₄ (мм)=Δ₅ (мм).The initial tube blank of the shell 1 (Fig. 1) of complex alloyed steels for cold deformation (22X3GN2M1FA, etc.) is first subjected to strain hardening by rotational drawing for several (two) transitions. One of the deforming rollers 3 (Fig. 1) is made with a rake angle $${\alpha }_3^{°}$$

1.5 ÷ 2.5 times less than the values of the front angles of the subsequent rollers 4 and 5, the rollers 3, 4 and 5 are installed in the same plane of the cross section along the tops of the profiles with a radial displacement C (mm) (figure 1) with gaps between the peaks and the mandrel 6 of the roller 3 - Δ ₃ (mm), roller 4 - Δ ₄ (mm) and roller 5 - Δ ₅ (mm), rollers 4 and 5 installed with the same clearances Δ ₄ (mm) = Δ ₅ (mm )

Then, at the last (third) transition, the shell blanks are subjected to thermal deformation hardening in the form of tempering operations with tempering, shot peening, rotational drawing and annealing, which reduces stress.

When thermodeformational hardening, hardening and tempering of the shell blanks is performed with heat setting on a sliding mandrel (Fig. 2). The blank of the shell 1 is installed on the housing 17 of the sliding mandrel with the focus of the end face of the workpiece in the support 14. In the clamping position, the rod 18, moved by the rod of the hydraulic cylinder 20, acts on the earrings 13, which transform the axial movement of the rod 18 into the radial movement of sectors 19, as a result fixing the shell blank 1 on the inner surface with the formation of radial tensile stresses in the blank, which, when quenched and tempered, counteract thermal stresses.

As a result, after heat hardening, the curvature of the generatrix and the ovality of the workpiece, the runout of the diametrical dimensions, are reduced.

After quenching and tempering to remove the blanks 1 from the mandrel, the hydraulic cylinder rod, returning to its original state, moves the thrust in the opposite direction, as a result of the earrings 13, the sectors 19 are also returned to their original position, freeing the shell blank from fixing. The spring 15 by means of a nut 16 holds through the draft and earrings of the sector in the initial position, and, after that, remove the workpiece from the mandrel.

After heat hardening the shell blanks, they are subjected to bead-blasting on the inner and outer surfaces in a bead-blasting machine, rotational extraction of the last (third transition) on a pressure-rolling machine and annealing of the reducing voltage in shaft furnaces.

The billet rings are subjected to hardening and tempering in chamber furnaces to the tensile strength of the material, comprising 0.6 ÷ 0.8 tensile strength of the material of the shell. Then, the turning of the shell blanks and rings is performed with the formation of the welded edges shown in FIG. four.

After that, the blanks of the shell 1 and the ring 2 are assembled on the expanding mandrel (Fig. 3), which is part of the welding installation together with a horizontal rotator, a welding machine, and a power source (not shown conventionally in Fig. 3). The work of the expanding mandrel is as follows. On the mandrel, in the compressed position of the sectors 7, set the blanks of the shell 1 and the ring 2 with a gap in the joint b (mm) (Fig. 4) equal to 0.15 ÷ 0.2 thickness of the welded edges (b = (0.15 ÷ 0.2) t _article ). Then, using the rod 9, the stop flange 10 and the earrings 11, the sectors 7 are moved to the right, which, moving along the conical surface of the stop 8, transmit the radial force to the inner surface of the edges of the shell 1 and ring 2, then there is a compression to align the joined edges with the calculated radial force of 5800 kgf by the amount of (0.1 ÷ 0.15)% of the actual circumference of the edges. Sectors 7 have rectangular grooves in which there are copper pads 12 for forming the reverse side of the seam and heat removal from the weld zone. After that, the joint of the assembled parts is automatically welded with a consumable electrode in one pass with through penetration of the welded edges. After welding the first joint, move the rod 9 to the left, bring the mandrel to its original state and remove the welded shell from the mandrel. Then, in the same sequence, the second joint of the shell and ring blanks is assembled and welded.

Next, the welded shell passes a low-temperature tempering of welds at a temperature of 400 ° C to reduce the level of residual stresses, preventing the formation of cold cracks, while maintaining high mechanical properties.

After low-temperature tempering, the weld seams of the shell are subjected to X-ray television inspection to identify internal defects in the metal of the welds and the heat-affected zone (lack of penetration, pores, slag inclusions).

Then, turning is performed on the welded shell rings to produce thrust threads.

In conclusion, hydraulic and pneumatic tests of the shell are carried out to verify the necessary strength and tightness of the welds and the entire shell.

Example.

The billet from ⌀180 × 20 mm pipes of structural complex alloyed cold-forming steels 22KH3GN2M1FA TU 1308-005-33116077-2001 is first subjected to strain hardening by a rotational hood on a pressure-rolling mill model RL 60/75 CNC for two transitions with a degree of deformation ε ₁ = 32.2 % - at the first transition (t ₀ = 11.8 mm, t = 8 mm) and ε ₂ = 40% - at the second transition (t ₀ = 8 mm, t = 4.8 mm).

At the last, third transition, thermodeformation hardening is performed in the form of hardening operations at a temperature of 910 ± 10 ° С with tempering at a temperature of 530 ± 10 ° С with heat setting on a sliding mandrel (Fig. 2) in a Ts-105A shaft furnace, shot blasting on the outside and the inner surface in shot blasting plants, rotary drawing with a degree of deformation of 45.8% (t ₀ = 4.8 mm, t = 2.6 mm) and annealing of the reducing voltage at a temperature of (400 ÷ 500) ° C in a shaft furnace.

After thermo-deformation hardening, the shell blanks have mechanical properties: tensile strength 1500 MPa, elongation δ = 8%.

Rotational drawing is performed (Fig. 1) by deforming rollers 3 with a front profile angle α ₃ = 15 °, rollers 4 and 5 with a front angle α ₄ = α ₅ = 30 °, (α _4,5 = 1,5 ÷ 2,5 ) α ₃ according to the claims).

The rollers 3, 4 and 5 are mounted with vertices in the same plane of the cross section (Fig. 1), with the displacement of the roller 3 relative to the rollers 4 and 5 in the radial direction, while the gap between the tops of the rollers and the mandrel 6 (Fig. 1) and the displacement , respectively:

Δ ₃ = 9.5 mm, Δ ₄ = Δ ₅ = 8 mm, s = 1.5 mm - at the first transition,

Δ ₃ = 6.1 mm, Δ ₄ = Δ ₅ = 4.8 mm, s = 1.3 mm at the second transition,

Δ ₃ = 3.7 mm, Δ ₄ = Δ ₅ = 2.6 mm, c = 1.1 mm at the third transition.

Then, turning is performed on the blanks of the shell 1 and rings 2 with the formation of welded edges (Fig. 4) in the form of conical sections of the joint and the thickness of the cylindrical sections t _article = 5.3 mm

Ring 3 before turning for assembly and welding is subjected to hardening and tempering in a shaft furnace with a tensile strength of 1050 MPa, which is 0.7 tensile strength of the shell material of 1500 MPa (0.6 ÷ 0.8 - according to the claims) .

After that, alternate assembly and welding of the shell 1 and the ring 2 on the expanding mandrel (Fig. 3) with a removable lining 12 (Fig. 4) with a gap in the joint b = 0.9 mm, which with the thickness of the welded edges t _article = 5, 3 mm is b = 0.17t _st (b = (0.15 ÷ 0.2) t _st according to the claims).

(0,1÷0,15% по формуле изобретения).During assembly and welding, the joint of the edges is performed by means of diametrical extension within elastic deformations of 0.56 mm, with an inner diameter of the shell and rings of 150 mm, the actual circumference of the edges is 3.14 × 150 = 471 mm, the value of elastic deformations is $$\frac{0,56}{\mathrm{four}7\mathrm{one}}\mathrm{one}00\%=0,\mathrm{one}2\%$$

(0.1 ÷ 0.15% according to the claims).

Automatic welding of the assembled shell 1 and ring 2 is performed by a consumable electrode in one pass with through-penetration of the welded edges. As a consumable electrode, OKAB Aristo Rod, a 1.6 mm diameter solid wire of ESAB brand, is used.

Assembly and welding of the shell 1 and rings 2 are performed alternately, first from one end of the shell, then from the other end of the shell (Fig. 5).

Then, low-temperature tempering of the shell welds at a temperature of 400 ° C in a shaft furnace is performed.

After low-temperature tempering, the welds are subjected to X-ray television control to detect internal defects in the weld metal and the weld zone (lack of penetration, pores, slag inclusions), they turn the welded shell rings to obtain threaded threads, and, in conclusion, conduct hydraulic and pneumatic tests for checking the necessary strength and tightness of the welds and the entire shell.

The method allows to provide high mechanical properties of welded shells (tensile strength, elongation, toughness) at a low level of residual internal stresses, high accuracy of geometric dimensions, strength of welded joints, processability of welding, operational reliability and high cyclic strength with a high metal utilization rate and low labor input.

Laboratory tests were carried out and a pilot batch of welded shells was manufactured.

Claims (2)

1. A method of manufacturing an axisymmetric welded shell operating under high pressure, consisting of a thin-walled shell with welded thickened rings, including machining the tube billet of the shell and rings, assembling them in the fixture, electric arc welding on one side in protective gases, final machining, control and testing of welds, characterized in that the pipe shell blank is made of structural alloy steel for cold deformation and is carried out strain hardening by a rotational hood for several transitions with deforming rollers with a front angle of one of the rollers 1.5–2.5 times smaller than the front angles of the subsequent rollers, while the rollers are installed in the same plane of the cross section along the vertices of their profiles and with an offset in the radial direction, and the aforementioned subsequent rollers - with the same clearances relative to the mandrel, and at the last transition, the tube billet is subjected to thermo-strain hardening in the form of tempering operations with heat-fixing the workpiece on a sliding mandrel, rotational drawing and annealing to reduce stress, after strain hardening, bead-blasting is performed on the outer and inner surfaces of the pipe billet, turning the pipe billet of the shell and rings with the formation of welded edges, alternately assembling the shell and rings on the expandable mandrel with a removable lining with a gap in the joint equal to 0.15-0.2 of the thickness of the welded edges and with the combination of the joint of the edges in the middle diametric tension within elastic deformations by (0.1 ÷ 0.15)% of the actual circumference of the edges, then the assembled parts are automatically welded with a consumable electrode in one pass with through-penetration of the welded edges, low-temperature tempering and X-ray television inspection of welded seams, turning of welded rings to obtain threaded threads, hydraulic and pneumatic tests of the resulting shell. 2. The method according to p. 1, characterized in that the billet rings before welding is subjected to hardening and tempering at a tensile strength of 0.6 ÷ 0.8 tensile strength of the material of the shell.

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