RU2710285C1 - Method of manufacturing steel thin-walled shells of high pressure vessels - Google Patents

Abstract

FIELD: technological processes.SUBSTANCE: invention relates to metal forming, particularly, to press, thermal and rotary treatment of steel thin-walled shells of high-pressure vessels. Cutting of pipes into workpieces, calibration, mechanical and rotary treatment is performed, wherein during calibration and rotary drawing there is used emulsion of perfluoropolyether acid in industrial oil as lubricant and lubricant-coolant, as well as antifriction fluorine-containing coating of deforming tool in the form of solution of perfluoropolyether silicon solution in coolant 113.EFFECT: higher stability of deforming tool, increased accuracy of geometrical dimensions and quality of treated surface, increased structural and cyclic strength and reduced internal stresses.3 cl, 2 dwg, 2 ex

Description

The invention relates to the field of metal forming, and in particular to methods for manufacturing steel pressure vessels and can be used in the manufacture of steel vessels from carbon and alloy steels working under pressure, used in various economic fields for the manufacture of fire extinguishers, oxygen and other gas cylinders.

High demands are placed on the vessels in terms of geometric accuracy, quality of the treated surface, tightness and strength.

The most important task in the manufacture of shells, which are the main body part of high-pressure vessels, is to ensure high accuracy of geometric dimensions, high quality of the processed surface, depending on the resistance of the deforming tool, as well as high structural and cyclic strength at high productivity and low cost.

A known method of manufacturing axisymmetric housings operating under pressure is RF patent No. 2295416, class. IPC V21D 51/24, publ. 03/20/2007, BI No. 8.

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

Alloy steel is used, hardening and tempering are carried out, rotational drawing is carried out without intermediate annealing.

There is also a method of manufacturing cylinders of structural low-carbon steels for liquefied gas, described in the patent of the Russian Federation No. 1798589, class. IPC R17C 1/00, publ. 02/28/1993.

The cylinder is made of butt-welded thin-walled shells obtained by a rotational hood.

The disadvantages of these methods is the low quality of the processed surface due to the low resistance of the deforming tool.

The closest in technical essence and the achieved technical result is a method of manufacturing steel thin-walled cylindrical parts by rotational drawing, described in the book of M.A. Gredor "Squeeze work and rotational extrusion", ed. Engineering, Moscow, 1971, p. 111, Fig. 66.67.

Three-roller pressing and rolling machines perform rotational extraction of thin-walled cylindrical parts from steel billets, obtained by extracting from a mug on pressing equipment. The workpiece is installed and fixed on the mandrel (item 1) fig. 66. Then the pressure rollers are pressed into the billet (poses II and III), providing thinning of the billet to a predetermined thickness in several transitions with intermediate annealing and etching of the oxide film.

When rotating the blanks from nickel or alloy steels, a cutting fluid is used in the form of one part of oil with twenty parts of water. The surface of the mandrel and the inner surface of the processed workpiece are coated with a lithium or colloidal zinc-based lubricant (p. 115).

The disadvantages of this method include the low accuracy and quality of the machined surface of the parts due to the low resistance of the deforming tool — the rollers and the mandrel, as well as the low metal utilization rate due to the use of the mug in the manufacture of blanks for rotary hoods using press equipment.

In addition, the use of a cutting fluid in the form of an oil-water mixture is ineffective due to the small amount of the lubricant of this mixture, and lithium or colloidal zinc-based lubricants are not universal and ineffective when processing carbon and alloy steel billets with a different chemical composition.

The disadvantage of the method adopted for the prototype is the application of lubricant only on the inner surface of the parts and on the outer surface of the mandrel, and the outer surface of the workpiece and the deforming rollers are left without lubrication.

The objective of the technical solution adopted by the applicant for the prototype is to obtain thin-walled cylindrical parts by rotational drawing on three-roller press-rolling machines from workpieces obtained by extracting from a mug on press equipment.

Common features with the method proposed by the applicants is the presence of press operations for the preparation of blanks, thermal operations in the form of annealing and rotary processing in the form of a rotational hood using cutting fluid and lubricant.

In contrast to the prototype, the method of manufacturing steel thin-walled shells of pressure vessels proposed by the applicants is based on the fact that they perform pipe cutting into measured billets, calibrate the billets on the outer or inner surface in one or several operations with preliminary, intermediate and final recrystallization annealing, preliminary mechanical processing, rotational extraction of workpieces for one or more transitions with annealing, which reduces internal stresses after the first and last of passes and annealing by recrystallization before the last transition, while during press and rotary processing, an emulsion of perfluoropolyether acid in industrial oil is used to lubricate the working surfaces of the deforming tool and workpieces, in addition, the antifriction fluorine-containing coating is applied to the working surfaces of the deforming tool of press and rotational processing, and then machining.

In special cases, that is, in specific forms of execution, the invention is characterized by the following features:

- as a lubricant of the working surfaces of the deforming tool and the outer surface of the workpieces use an emulsion of perfluoropolyether acid 6MFK-180 in industrial oil with a ratio of components, mass%: (0.2 ÷ 10) and (99.8 ÷ 90), respectively;

- an antifriction fluorine-containing coating in the form of a (0.5 ÷ 5)% solution of perfluoropolyether acid 6MFK-180 in freon 113 is applied to the working surfaces of the deforming tool.

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 the possibility of manufacturing steel thin-walled shells of pressure vessels with high accuracy of geometric dimensions and surface quality, structural and cyclic strength, high resistance to the deforming tool, high metal utilization, low labor and manufacturing costs.

The specified technical result during the implementation of the invention is achieved by the fact that with the known method, including pressing, heat and rotary processing of workpieces using cutting fluid and lubricant, the feature is that the pipes are cut into measured workpieces, the workpieces are calibrated according to external or internal surfaces for one or several operations with preliminary, intermediate and final recrystallization annealing, preliminary machining, rotary drawing billets for one or several transitions with annealing that reduces internal stresses after the first and last transitions and recrystallization annealing before the last transition, while in the press and rotary processing, an emulsion of perfluoropolyether acid in industrial oil is used as a lubricant for the working surfaces of the deforming tool and the workpieces, in addition an antifriction fluorine-containing coating is applied to the working surfaces of the deforming tool, then the final mechanical rabotku.

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

- cutting pipes into measured billets to increase the utilization of metal;

- calibration of the workpieces for one or more operations on the outer or inner surface, depending on the nomenclature of the pipes, to provide the necessary diametrical dimensions of the workpieces for subsequent processing;

- preliminary, intermediate and final recrystallization annealing to remove hardening, increase ductility and reduce the hardness of the metal blanks for calibration and for further mechanical and rotary processing;

- preliminary machining to ensure the necessary dimensions of the workpieces for a rotational hood;

- rotary drawing of blanks for one or several transitions with intermediate annealing to obtain a thin-walled shell with high accuracy of geometric dimensions and the quality of the processed surface;

- performing annealing, which reduces internal stresses after the first and last transition, reduce the level of internal residual stresses of the workpieces without reducing the tensile strength of the metal of the workpiece;

- perform recrystallization annealing before the last transition of the rotary hood to remove metal hardening, increase ductility and reduce the hardness of the workpiece metal;

- the use of perfluoropolyether acid acid emulsion in industrial oil as a lubricant for the working surfaces of the deforming tool and the workpiece emulsion, to reduce the friction force in the deformation zones, to increase the accuracy and quality of the surface of the shells and to increase the resistance of the deforming tool;

- applying an antifriction fluorine-containing coating to the working surfaces of the deforming tool, increase the service life of the deforming tool, reduce the time spent on replacing the worn tool, increase the accuracy and quality of the surface to be treated, reduce the complexity and cost of manufacturing shells;

- perform the final machining to prepare blanks of shells for connection with components.

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

- use as a lubricant the working surfaces of the deforming tool and the outer surface of the workpieces of the emulsion of perfluoropolyether acid 6MFK-180 in industrial oil with a ratio of components, mass%: (0.2 ÷ 10) and (99.8 ÷ 90), respectively, to ensure the optimal ratio of components , when the content of perfluoropolyether acid is less than 0.2%, the friction force increases, when the content is more than 10%, the consumption of perfluoropolyether acid increases and the cost of the emulsion increases;

- applying on the working surfaces of the deforming tool an antifriction fluorine-containing coating in the form of a (0.5 ÷ 5)% solution of perfluoropolyether acid 6MFK-180 in Freon 113 to ensure the optimal ratio of the components of the solution, since when the content is less than 0.5% perfluoropolyether acid in the solution, the tool wear resistance decreases, and with a content of more than 5%, the consumption of perfluoropolyether acid increases and the cost of the solution increases.

The features 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."

Examining the prior art during a patent search on 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 thin-walled steel shells of pressure vessels, pipes are cut into measured billets, the billets are calibrated on the outer or inner surface in one or more operations with preliminary, intermediate and final recrystallization annealing, preliminary mechanical processing, rotary drawing blanks for one or more transitions with annealing that reduces internal stresses after the first and last transitions and annealing the regs stallizatsionnym before the last passage, wherein when the rotary press and processed as a lubricant working surfaces of the deforming tool and workpiece perftorpoliefirkisloty emulsion used in industrial oil, in addition to the working surfaces of the deforming tool is applied a fluorine-containing anti-friction coating, then perform final machining.

The invention is illustrated by drawings, where in FIG. 1 shows the calibration process of pipe blanks 2 ₁ and 2 _{2 with a} punch 1 in a matrix 3 installed in a band 4, 5 - a lubricant filled into the cavity between the matrix 3, a band 4 and a workpiece 2 ₁ , A and B - the working surfaces of the punch 1 and matrices 3.

In FIG. 2 shows the process of rotational drawing of a workpiece 6 with a wall thickness t ₀ (mm) for several transitions by deforming rollers 10 on the mandrel 11.

The workpiece 6 is mounted on the mandrel 11 and fixed on it by a ring 12 and a clip 13.

In FIG. 2 also shows: 7 — blank of the first transition, auto-path of the rollers 10 of the first transition, t ₁ (mm) - wall thickness of the blank of the first transition, 8 — blank of the second transition, cd — path of the rollers 10 of the second transition, t ₂ (mm) - wall thickness blanks of the second transition, 9 - blank of the last transition, ef - trajectory of the rollers 10 of the last transition, t ₃ (mm) - wall thickness of the blank of the last transition.

In - the working surface of the rollers 10.

G - the working surface of the mandrel 11.

S _min ^-1 - the rotation speed of the mandrel and the workpiece.

F _{mm / min} - axial feed rollers.

The proposed method for the manufacture of steel thin-walled shells is as follows.

Initially, pipes are cut from carbon and alloy steels into measured billets on pipe-cutting machines.

Recrystallization softening annealing is performed in electric furnaces. Then the workpieces are calibrated on the outer or inner surface in one or several operations, depending on the nomenclature of the pipes, on hydraulic presses with intermediate and final recrystallization softening annealing.

During the working stroke of the press, lubricating fluid 5, based on an emulsion of perfluoropolyether acid in industrial oil, enters the working surfaces A and B of the deforming tool - the punch 1 and matrix 3, and the outer surfaces of the workpieces 2 ₁ and 2 ₂ .

An antifriction fluorine-coated coating is applied to the working surfaces A of the punch 1 and B of the matrix 3.

After this, preliminary mechanical - turning is performed on lathes on the outer and inner and end surfaces to obtain the required dimensions for subsequent rotational drawing. Get the workpiece 6 (Fig. 2) for further processing.

A rotary hood is performed on press-rolling machines for one or more transitions (Fig. 2) by deforming rollers 10 on the mandrel 11.

A blank 6 with a wall thickness t ₀ (mm) is mounted on the mandrel 11 and fixed on it with a ring 12 and a clamp 13.

Rotary drawing for several transitions is performed with intermediate annealing, which reduces internal stresses after the first and last transitions and with recrystallization softening annealing before the last transition.

At the first transition, a workpiece 7 with a thickness of t ₁ (mm) is obtained when moving the rollers 10 along the path Av, a workpiece 8 with a thickness of t ₂ (mm) is obtained at the second transition when the rollers 10 are moving along the cd path, the workpiece 9 with a thickness of t ₃ (mm ) - at the last transition when moving the rollers along the path ef.

In the process of rotational drawing, as an lubricant of the working surfaces B and D, respectively, of the rollers 10 and the mandrel 11 and the workpieces 6, 7, 8, an emulsion of perfluoropolyether acid in industrial oil is used on the outer surface.

On the working surfaces B and D, respectively, of the rollers 10 and the mandrel 11, an antifriction fluorine-containing coating is applied.

Perform the final mechanical - turning.

Example 1

Hot-deformed pipes made of alloy steel SP28 (28H3SNMVFA) are cut into measuring billets on pipe-cutting machines.

Get tube blanks measuring 425 × 20 mm and a length of 500 mm. Recrystallization softening annealing is performed in electric furnaces.

Then the tube blanks are calibrated by the outer diameter (Fig. 1) in two operations with intermediate and final recrystallization annealing.

Before calibration, a high-resistance antifriction fluorine-containing coating in the form of a (0.5-5)% solution of perfluoropolyether acid 6MFK-180 in Freon 113 with a long life and many times increasing the service life of the deforming tool is applied to the working surfaces A of the punch 1 and B of matrix 3.

During the working stroke of the press, lubricating fluid 5 (Fig. 1) in the form of an emulsion of perfluoropolyether acid in industrial oil with a ratio of components, mass%: (0.2 ÷ 10) and (99.8 ÷ 90), respectively, comes from the cavity between the bandage 4 and the workpiece 2 ₁ on the working surface B of the matrix 3 and on the outer surface of the workpieces 2 ₁ and 2 ₂ .

After the first transition of calibration, blanks of shells of 420 × 20 mm in size are obtained, and after the second transition of 415 × 20 mm in size.

Then, preliminary turning is performed on lathes to obtain a blank 6 with a size of 412 × 12 (mm) (Fig. 2).

Perform a rotational hood billet 6 (Fig. 2) for three transitions on press-rolling machines.

After the first transition, a workpiece 7 with a wall thickness t ₁ = 8 (mm) is obtained, after the second transition, a workpiece 8 with a wall thickness t ₂ = 5 (mm) is obtained, after the third transition, a workpiece 9 with a wall thickness t ₃ = 2.5 (mm) )

After the first and third transitions, annealing is performed to reduce internal stresses.

Before the third transition, recrystallization softening annealing is performed.

Before the rotary hood, on the working surfaces B and D of the deforming tool — rollers 10 and mandrel 11, a high-resistance antifriction fluorine-containing coating is applied in the form of a (0.5–5)% solution of perfluoropolyether acid 6MFK-180 in Freon 113 with a long term of operation, which significantly increases the life of the rollers and mandrels.

Before each transition of the rotary hood to the working surfaces of B and D of the rollers 10 and mandrel 11, as well as to the outer surfaces of the blanks 6, 7 and 8, grease is applied in the form of an emulsion of perfluoropolyether acid in industrial oil, with a ratio of components, mass%: (0.2 ÷ 10) and (99.8 ÷ 90), respectively.

In the process of rotational drawing at each transition, cutting lubricants in the form of industrial oil are supplied to the working surfaces of the rollers, mandrels and the outer surfaces of the workpieces.

Then perform the final turning.

Example 2

Hot-deformed carbon steel steel 10 pipes are cut into dimensional blanks of 425 × 18 mm in length and 425 mm in length.

Recrystallization softening annealing is performed.

Before calibration, a high-resistance antifriction coating is applied to the working surfaces of the punch 1 and die 3 (Fig. 1) (see example 1)

Then the tubular billets are calibrated by the outer diameter in one operation to obtain a billet with a size of 420 × 18 mm.

During the working stroke of the press, lubricant 5 enters the working surfaces B of the matrix 3 and the outer surface of the workpieces (see example 1).

Recrystallization softening annealing is performed.

Then, preliminary turning is performed to obtain a workpiece 6 (Fig. 2) with dimensions of 416 × 12 mm.

Before the rotary hood, on the working surfaces B and D of the rollers 10 and the mandrel 11, a highly resistant antifriction fluorine-containing coating is applied (see example 1).

Rotate the billet 6 for two transitions with recrystallization softening annealing before the second transition.

Before each transition of the rotary hood to the working surfaces B and D of the rollers 10 and the mandrel 11, as well as on the outer surfaces of the workpieces 6,7 apply lubricant (see example 1).

In the process of rotational drawing, cutting fluid is supplied at each transition (see example 1).

After the first transition, a workpiece 7 with a thickness of t ₁ = 6.5 mm is obtained, after the second transition, a workpiece 8 with a thickness of t ₂ = 2.2 mm is obtained.

Perform annealing to reduce stress.

In conclusion, perform the final turning.

The implementation of the method in accordance with the invention enables the manufacture of steel thin-walled shells of pressure vessels with high accuracy and quality of the processed surface, high resistance to the deforming tool, high structural and cyclic strength, low residual stresses, high metal utilization, low labor and production costs.

The invention can be used in the manufacture of various steel shells.

The indicated positive effect is confirmed by tests of shells made by this method.

Claims (3)

1. A method of manufacturing steel thin-walled shells of pressure vessels, including pressing, heat and rotary processing of workpieces using cutting fluid and lubricant, characterized in that the pipe is cut into measured workpieces, calibrating the workpieces on the outer or inner surface in several operations with preliminary, intermediate and final recrystallization annealing, preliminary machining, rotational drawing of billets with annealing, reducing internal voltage after the first and last transitions and recrystallization annealing before the last transition; in this case, during press and rotary processing, an emulsion of perfluoropolyether acid in industrial oil is used to lubricate the working surfaces of the deforming tool and the workpieces, and an antifriction fluorine-containing coating is applied to the working surfaces of the deforming tool, then the final machining. 2. The method according to p. 1, characterized in that as a lubricant of the working surfaces of the deforming tool and the outer surface of the workpieces use an emulsion of perfluoropolyether acid 6MFK-180 in industrial oil with a ratio of components, wt. %: (0.2 ÷ 10) and (99.8 ÷ 90), respectively. 3. The method according to p. 1, characterized in that an antifriction fluorine-containing coating is applied to the working surfaces of the deforming tool in the form of a (0.5 ÷ 5)% solution of perfluoropolyether acid 6MFK-180 in freon 113.

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