RU2748843C1 - Method for manufacturing welded thin-walled conical part consisting of shell and body parts welded to it along annular joints - Google Patents

Abstract

FIELD: welding production.

SUBSTANCE: invention relates to the field of welding production of thin-walled conical parts, consisting of shells and body parts, welded together at annular joints. The method includes manufacturing a shell and body parts welded to it, for example bottoms, flanges or bushings, assembling the parts to be welded on one-piece backing rings and welding circular joints. The body parts from the side of the annular joints are made with larger diameters than the diameter of the butted shell, without changing the specified thickness of the welded edges in the places of the annular joints, while the diameter of the body parts from the side of the annular joints is determined according to the corresponding formula, taking into account the shrinkage of a particular material, the welding method and the taper angle.

EFFECT: use of the invention makes it possible to reduce the complexity of manufacturing, as well as to improve the quality and accuracy of the geometric parameters of the finished product.

3 cl, 1 dwg

Description

The invention relates to the field of mechanical engineering, namely to the assembly and welding of circular joints of thin-walled conical shells and body parts, for example, such as bottoms, flanges, bushings, and can be used in the production of casings, sockets, containers and other products.

A known method of assembly for welding of circular joints on expanding rings (reference book "Welding and materials to be welded", volume II edited by VM Yampolsky, ed. MSTU named after NE Bauman, 1996, pp. 47-48). The method of assembly for welding involves the following operations: manufacturing of assembly units, assembly and adjustment of the welded edges of parts without displacement, installation of parts on a backing ring, welding.

This method of assembly for welding of circumferential joints of parts is carried out without displacement of the welded edges. When welding tapered parts, it is difficult to ensure the fit of the parts to ensure assembly without displacement of the welded edges. This method leads to the formation of displacement of the edges after welding as a result of welding deformations, which significantly reduces the quality of the welded joint and, accordingly, the quality and accuracy of the geometric parameters of the assembly unit.

Common features for the analogue and the claimed invention are: production of assembly units; assembly, installation of parts on a backing ring, welding.

There is also known a method of assembling for welding the circumferential joints of containers (RF patent No. 2290290, IPC V23K 37/04, publ. 27.12.2006), taken as a prototype, including the manufacture of shells and bottoms, the assembly of welded parts on a collapsible backing ring, welding of an annular joint and removal of the backing ring. Before assembly, the edges of the parts to be welded are heated with an external flexible heating element and, in the heated state, are freely pushed onto the backing ring assembled outside the container until the end surfaces of the parts to be welded are fully in contact, the heating element is turned off and the resulting assembly is cooled to room temperature, after which the circular joint is welded and the backing is removed. ring.

The disadvantage of this method is the complexity and duration of the technological process of preparatory and final assembly work, welding of parts. This is due to the fact that it is required to carry out such operations as:

- winding a flexible heating element on the edges of the parts to be welded, which is difficult when welding tapered parts;

- preheating the edges of the parts to be welded, which requires additional energy consumption;

- assembly and disassembly of a complex backing ring consisting of several parts.

In addition, after welding conical thin-walled parts by this method, the occurrence of displacement of the edges due to welding deformations of the metal is inevitable, which leads to a change in the geometric parameters of the assembly unit.

Common features for the prototype and the claimed invention are:

production of the shell and the bottom (body part) to be welded to it, assembly of the parts to be welded on the backing ring, welding of the circular joint.

The objective of the invention is to develop a method for assembling and welding thin-walled conical shells and body parts with the investment of minimum labor and energy costs for preparatory and final work, ensuring the quality of the weld and the accuracy of the geometric parameters of the assembly unit.

When solving this problem, the following technical results are achieved:

- exclusion of preparatory and final operations: winding a flexible heating element on the edges of the parts to be welded; preheating the edges of the parts to be welded, which requires additional energy consumption; assembly and disassembly of the backing ring;

- elimination of displacement of edges after welding of tapered thin-walled parts due to welding deformations of the metal;

- ensuring the accuracy of the geometric parameters of the assembly unit.

The technical results are achieved by the fact that in the method of manufacturing a welded thin-walled conical part, consisting of a shell and body parts welded to it along the annular joints, including the manufacture of the said shell and body parts, assembling the shell and body parts to be welded on backing rings and welding the annular joints of the shell and of body parts, according to the invention, said body parts from the side of the annular joint to be welded are made with a diameter greater than the diameter of the shell from the side of the corresponding welded annular joint without changing the predetermined thickness of the welded edge at the place of the annular joint, which is determined by the formula:

∅c.d = rev. + 2 * δ * K ₁ * K ₂ * K ₃ , where

∅c.d. - diameter of the body part from the side of the welded annular joint,

Ob. - diameter of the shell from the side of the welded annular joint,

δ is the thickness of the welded edge of the part at the place of the annular joint,

K ₁ - coefficient taking into account material shrinkage depending on the welding method,

K ₁ = 0.3 for welding in shielded gases, K ₂ is a coefficient that takes into account the shrinkage of the material depending on the grade of the material of the parts, K ₂ = 1 for steel, K ₁ = 0.9 for titanium, K ₂ = 0.8 for aluminum,

K ₃ - coefficient taking into account shrinkage of the material depending on the taper angle of the shell and body parts, K ₃ = 1.0 for the taper angle α = 30 ... 45 °, K ₃ = 0.8 for the taper angle α = 46 ... 60 °.

The mentioned body parts are made in the form of a bottom, a flange or a sleeve. Backing rings are used in the form of one-piece backing rings, the diameters and taper angle of which correspond to the inner diameters and taper angle of the shell.

The essence of the method of assembling for welding the circumferential joints of thin-walled conical parts is illustrated by the drawing - Fig. 1 - assembly unit - conical shell with bottom and flange, where:

1 - faceplate (base surface) for basing and carrying out assembly and welding works; 2 - shell, 3 - bottom, 4 - flange, 5 - backing rings installed on the racks 6 of the faceplate 1.

The method of assembling for welding the circumferential joints of a thin-walled conical part, for example, a shell with body parts, for example, a bottom, a flange, a sleeve, is carried out as follows (Fig. 1).

Shell 2 is made, body parts are bottom 3, flange 4, while bottom 3 and flange 4 from the side of the welded annular joints are made with larger diameters than the diameter of the shell 2, without changing the specified thickness 6 of the welded edges at the annular joints. The diameter of the bottom 3 and flange 4 from the side of the welded annular joints is determined by the formula:

∅c.d = ∅o6. + 2 * S * K ₁ * K ₂ * K ₃ , where

∅c.d. - diameter of body parts - bottom 3 and flange 4 from the side of the welded annular joints;

Ob. - the diameter of the shell 2 from the side of the welded annular joint;

δ is the thickness of the welded edges of parts 2, 3, 4 in the places of the annular joints;

K ₁ - coefficient taking into account material shrinkage depending on the welding method;

K ₂ - coefficient taking into account the shrinkage of the material, depending on the grade of the material of the parts;

K ₃ - coefficient that takes into account the shrinkage of the material depending on the taper angle of the shell 2 and body parts 3, 4;

Assembly for welding of parts 2, 3, 4 is carried out on one-piece backing rings 5, the diameters and taper angle of which correspond to the inner diameters and taper angle of the shell. The well-known typical design of the backing ring 5 is presented in the book "Technology of electric fusion welding of metals and alloys" edited by academician B.Ye. Paton, "Mechanical Engineering", 1974, p. 188.

The values of the coefficients K ₁ , K ₂ , K _{3 are} determined empirically and are:

K ₁ = 0.3 for gas-shielded welding

K ₂ = 1 for steel

K ₂ = 0.9 for titanium

K ₂ = 0.8 for aluminum

K ₃ = 1.0 for α = 30 ÷ 45 °

K ₃ = 0.8 for α = 46 ÷ 60 °,

α is the taper angle of the shell.

On the base surface of the device, for example, the faceplate 1 with the support posts 6 installed on it, one-piece backing rings 5 are fixed, the diameters and taper angle of which correspond to the inner diameters and the taper angle of the shell 2. The parts to be welded are assembled in the following sequence: on the faceplate 1-on it centering base surface - fix the flange 4; on one-piece backing rings 5 install the shell 2, while the shell 2 contacts the tapered base surfaces of the backing rings 5 and the end surface of the flange 4; then the bottom 3 is installed on the end surface of the shell 2. During the assembly process, the displacement of the welded edges of parts 2, 3, 4 is uniformly distributed along the entire length of each welded annular joint, after which welding is performed in shielding gases. After welding, the assembly unit is removed from the backing rings 5 of the faceplate 1.

Due to the implementation of the bottom 3 and flange 4 on the side of the welded circular joints with diameters larger than the diameter of the butted shell 2, without changing the specified thickness of 5 welded edges in the place of the annular joint, and the use of backing rings 5 with diameters and taper angle corresponding to the inner diameters and angle taper of the shell 2, in the process of welding, as a result of metal melting and due to plastic deformations, the ends of the shell 2 rise relative to the ends of the body parts 3, 4 by the amount of displacement of the edges to be welded, given by the difference between the diameters of the shell 2 and body parts 3 and 4, which is necessary and sufficient to obtain the specified accuracy of the geometric parameters of the product. In addition, the cost of energy consumption and labor costs have decreased when implementing the claimed method of assembling parts for welding.

An example of the implementation of the method.

A conical shell with a height of 119 mm with a taper angle of 45 °, a thickness of 3 mm, a large diameter - 575 mm, and a smaller diameter - 290 mm was made from sheet material KhN45MVTYUBR-ID (EP718-ID). The body parts - bottom 3 and flange 4 from forgings, material grade of bottom 3 and flange 4 - KhN45MVTYUBR-ID (EP718-ID) were manufactured. In this case, the diameters of the bottom 3 and flange 4 on the side of the welded circular joints were made with larger diameters than the diameters of the butted shell 2, without changing the specified thickness of the welded edges at the annular joints.

The diameters of the body parts - bottom 3 and flange 4 were determined by the formula:

∅c.d. = ∅ob. + 2 * 5 * K ₁ * K ₂ * K ₃ , where

∅c.d. - diameter of body parts - bottom 3 and flange 4 from the side of the welded annular joints;

Ob. - the diameter of the shell 2 from the side of the welded annular joint;

δ is the thickness of the welded edges of parts 2, 3.4 in the places of the annular joints;

K ₁ - coefficient taking into account material shrinkage depending on the welding method;

K ₂ is a coefficient that takes into account the shrinkage of the material depending on the grade of material of parts 2, 3, 4;

K ₃ - coefficient taking into account material shrinkage depending on the taper angle of parts 2, 3, 4;

In this case, the coefficients are selected taking into account the initial data.

The following values of the coefficients are established:

K ₁ = 0.3 (welding in shielded gases);

K ₂ = 1 (for steel);

K ₃ = 1.0 (for α = 30 ÷ 45 °);

α is the taper angle of the shell;

δ - 3 mm (thickness of the edges to be welded).

For the larger diameter of the shell - 575 mm, flange 4 was made with a diameter determined by the formula for welding in shielded gases:

∅ = 575 + 2 * 3 * 0.3 * 1 * 1 = 576.8 mm.

For the smaller diameter of the shell - 290 mm, a bottom 3 with a diameter determined by the formula for welding in shielded gases was made:

∅ = 290 + 2 * 3 * 0.3 * 1 * 1 = 291.8 mm.

The parts were assembled for welding on solid backing rings 5, the diameters and taper angle of which correspond to the inner diameters and taper angle of the shell 2, while argon was supplied to the backing rings 5 to protect the weld root from oxidation.

The assembly for welding of parts 2, 3, 4 was carried out on the base surface of the faceplate 1. First, preparations were made for the assembly of parts 2, 3, 4 in the following sequence: on the base surface of the faceplate 1 with the support posts 6 installed on it, the backing rings 5 were fixed at a distance relative to each other, corresponding to the shell height - 119 mm. Next, the parts to be welded 2, 3, 4 were assembled in the following sequence: on faceplate 1 - flange 4 was fixed on its centering base surface; a shell 2 was installed on the backing rings 5, while the shell 2 contacts the base conical surfaces of the backing rings 5 and the end surface of the flange 4; further, the bottom 3 was installed on the end surface of the shell 2. During the assembly process, a uniform distribution of the displacement of the welded edges of parts 2, 3, 4 along the entire length of each welded annular joint was ensured. Tack welds were performed by manual argon-arc welding at each welded circumferential joint (tacks at a distance of 80-120 mm). The faceplate 1 with the assembled parts 2, 3, 4 was installed on the welding positioner, fixed, and the assembly unit was tilted to a horizontal position. After that, automatic argon-arc welding of each joint was performed in two passes: the first pass - without wire, the second pass - with Sv-EP533 wire.

In the process of welding, due to welding deformations, the metal melts and the ends of the shell 2 are raised relative to the ends of the body parts 3, 4 by the amount of displacement of the edges being welded, given by the difference between the diameters of the shell 2 and body parts 3 and 4, which is necessary and sufficient to obtain the specified accuracy of the geometric parameters of the product. After welding, the faceplate 1 was detached, the finished product was removed, and further operations were performed (plumbing, heat treatment, X-ray inspection, etc.). The finished product meets the specified quality and geometric parameters.

The practical implementation of the claimed method of assembly for welding of circular joints of thin-walled conical parts allows conclusions to be drawn about its industrial (technical) feasibility with the achievement of the above technical results.

The proposed method, in comparison with the prototype, makes it possible to reduce the labor intensity of the assembly process for welding the circumferential joints of thin-walled conical shells, to provide high-quality welded seams and geometric parameters of the finished product, and to reduce the cost of electricity consumption.

Claims (10)

1. A method of manufacturing a welded thin-walled conical part, consisting of a shell and body parts welded to it along the annular joints, including the manufacture of the mentioned shells and body parts, assembling the shell and body parts to be welded on backing rings and welding the annular joints of the shell and body parts, characterized in that that the said body parts from the side of the annular joint to be welded are made with a diameter greater than the diameter of the shell from the side of the corresponding welded annular joint without changing the predetermined thickness of the welded edge at the place of the annular joint, which is determined by the formula

, where ∅c.d. - diameter of the body part from the side of the welded annular joint, Ob. - diameter of the shell from the side of the welded annular joint, δ is the thickness of the welded edge of the part at the place of the annular joint, K ₁ - coefficient taking into account the shrinkage of the material depending on the welding method, K ₁ = 0.3 for welding in shielded gases, K ₂ is a coefficient that takes into account the shrinkage of the material depending on the grade of the material of the parts, K ₂ = 1 for steel, K ₂ = 0.9 for titanium, K ₂ = 0.8 for aluminum, K ₃ - coefficient taking into account shrinkage of the material depending on the taper angle of the shell and body parts, K ₃ = 1.0 for the taper angle α = 30 ... 45 °, K ₃ = 0.8 for the taper angle α = 46 ... 60 °. 2. A method according to claim 1, characterized in that said body parts are made in the form of a bottom, a flange or a sleeve. 3. A method according to claim 1 or 2, characterized in that the backing rings are used in the form of one-piece backing rings, the diameters and taper angle of which correspond to the inner diameters and the taper angle of the shell.

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