RU2461436C1 - Method of producing variable cross-section thin-wall shells - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to metal forming, particularly, to production of thin-wall high-strength shells from steel tube billets. Tubes made from killed steel represent said billets. Forming is performed by rotary and/or press processing to produce curvilinear, transition and cylindrical sections with axial direction of deformation. First, machined are transition conical and curvilinear parts with wall thickness and ultimate strength increasing and diameter decreasing toward reduced end. Then, transition part with variable cross-section and cylindrical part with tapering wall sections are processed in opposite direction. Note here that transition part is formed with cylindrical fillet with inclination of smaller than inclination of transition part generatrix in initial machining. At the end of machining, annealing is performed to reduce strain at 340-360°C.

EFFECT: higher surface precision and quality.

10 cl, 8 dwg, 1 tbl, 2 ex

Description

The invention relates to the field of metal forming, in particular to the manufacture of thin-walled cases of variable cross-section from steel pipe billets by methods of metal forming - rotary and press machining.

Thin-walled enclosures of variable cross-section are used in the manufacture of pressure vessels - cylinder bodies, liners, fire extinguishers, operating under the internal pressure of fillers, and under external influence - in fires, underwater works, etc. extreme conditions.

The most important problems in the production of thin-walled enclosures of variable cross section, which are axisymmetric shells with conical or curvilinear and cylindrical parts of various thicknesses, are high geometric dimensions, high metal utilization, productivity and high mechanical properties with small wall thicknesses.

A feature of thin-walled enclosures of variable cross section is the thin wall of the cylindrical part and the large and variable wall thickness of the curved part.

There are many known methods of manufacturing such shells by metal forming - rotary drawing and rotary crimping of rotary processing, drawing and crimping of a press treatment.

In the book of V.P. Romanovsky. Cold Stamping Handbook. L .: Engineering, 1979, p. 158 in the chapter "Extraction of conical-shaped parts", Fig. 135, "a" and "b" describes methods for drawing out conical parts with a taper angle from 10 ° to 30 °.

The disadvantage of this method is the low utilization of metal, since the initial billet is a circle, as well as a large number of operations, which leads to the high complexity of manufacturing parts.

Chapter 32 “Crimping” of the same reference book describes methods of crimping tube blanks Fig. 195, 2, which shows the crimping of tube shells with a taper angle α = 20 ° and a stretch with an angle α = 40 °. Stretching and crimping can be performed in one operation with a significant difference in the diameters of the cylindrical and crimped parts.

The disadvantages of the described methods of press processing include the inability to obtain wall thicknesses of various thicknesses of the compressed and cylindrical parts.

In the book of N.I. Mogilny. "Rotational extraction of shell parts on machines." M: Engineering, 1983, p.110, 111 in the chapter "7. Selection and calculation of the workpiece" in Fig.6.11 shows a method of manufacturing conical and curved shells from sheet and forged blanks by rotational drawing by projection in one or two transitions.

The disadvantages of this method also include the low utilization of metal and the inability to obtain a cylindrical part of the shell.

In the book of V.G. Kaporovich. "Running-in in the manufacture of metal products." M .: Engineering, 1973, pp. 7–22, in the chapter “2. Rolling out cones on a mandrel”, various methods for producing shells from both tubular and flat blanks, without mandrels and mandrels, with a friction tool and rollers, which cylindrical shells with conical and curved neck profiles with a variable wall thickness are obtained.

The main disadvantage of these methods, in relation to the problem of obtaining thin-walled enclosures of variable cross section, is the lack of solutions for thinning the cylindrical and mating transitional parts of the shell.

The closest in technical essence and the achieved technical result is the "Method of manufacturing hollow products" and.with. No. 719750, class B21D 22/06, BI No. 9, 1980, in which a tube billet is used, by pressing, first crimp onto the cone, then crimp and hot upset the bulge at the end of the crimped part, then distribute the cylindrical part and, at the end of the treatment, extract with a thinning of the cylindrical part, when crimping, the taper angle is set (see sheet 4) within 7 ÷ 15 °, the wall thickness is kept increasing toward the crimped end, distribution is carried out with a degree of deformation of 0.7 ÷ 1.3% of the degree during crimping.

This method is adopted by the authors for the prototype.

As can be seen from this technical solution, the pressing process is carried out in four operations, first, crimping the conical part, then crimping the curvilinear part and hot landing of the thickening at the pressed end, then distributing and drawing out with thinning of the cylindrical part.

The reasons that impede the achievement of the specified technical result when using the known method adopted by the authors for the prototype include uneven deformation in the transition zone of the curved compressed part to the cylindrical one, which leads to the formation of metal tightenings, cracks and the separation of the cylindrical part during the hood with thinning.

In addition, the prototype provides a formula for changing the wall thickness when crimping a cone with an angle of inclination of the generatrix of 7 ÷ 15 °, which is not applicable when crimping workpieces with a curvilinear generatrix with a large range of production of cases for various purposes.

The prototype also does not reflect signs that affect the performance of the housings: a change in the mechanical properties of the curvilinear part, the direction of deformation, the ratio of the degrees of deformation during the formation of curvilinear and cylindrical parts, the temperature conditions of the final heat treatment, as well as the use of rotational processing, which affects the accuracy and quality of processing .

Thus, the objective of this technical solution adopted by the applicants for the prototype was to create a method for manufacturing hollow products by pressing - crimping the conical part, crimping and hot upsetting the inner thickening and then distributing and drawing out the cylindrical part in order to increase the metal utilization rate.

Common features with the method proposed by the authors is the use of a pipe billet, crimping one part of the billet and drawing another.

In contrast to the prototype, in the method of manufacturing thin-walled cases of variable cross section proposed by the authors, steel tubes of a quiet grade with a tensile strength of 32 ÷ 65 (kgf / mm ² ) are used as a workpiece, forming is performed by rotational and or press processing of the workpiece with the formation of a curved, transitional and of the cylindrical parts with the axial direction of deformation, first the transitional conical and curvilinear parts with a wall thickness and tensile strength of the material are increased, and the diameter is reduced moving towards the crimped end, then in the opposite direction, the transition part with a variable wall thickness and cylindrical with thinning of the wall, while the transition part is formed with a cylindrical girdle and a conical section with an inclination angle forming less than 1.5 ÷ 2.5 times the angle of inclination forming the transitional part during its initial processing and, at the end of the processing, annealing reduces stress at a temperature of 340 ÷ 360 ° C.

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

- crimping of the curved part is performed with a wall thickness at the crimped end equal to 1.1 ÷ 1.5 of the wall thickness of the workpiece;

- crimping the transitional and curvilinear parts is performed with a tensile strength of the material in the direction of decreasing the diameter to the end, changing according to:

where σ _B (kgf / mm ² ) is the current value of tensile strength,

σ _{B ref} (kgf / mm ² ) - initial value of tensile strength,

ε (%) is the degree of deformation of the crimp,

α ° - the current value of the cone angle of the curved part;

- a cylindrical belt of the transitional part of the workpiece during drawing is formed by a length not exceeding the wall thickness of the workpiece;

- the transitional part of the workpiece during the hood with thinning is formed with the wall thickness of the workpiece of the conical section, decreasing in the direction from the curved part to the cylindrical;

- preform shaping is carried out first by rotational crimping of the transitional and curvilinear parts, and then by extraction with thinning of the transitional and cylindrical parts by pressing;

- the workpiece is shaped by pressing - first crimping curvilinear, then distributing the transitional, cylindrical and curvilinear parts, and then a rotational hood with thinning the wall of the transitional and cylindrical parts;

- the degree of deformation of the cylindrical part of the workpiece during distribution is equal to the degree of deformation of the change in diameter during drawing with thinning of the wall of the same part;

- crimp curvilinear and the distribution of the cylindrical and transitional parts is performed by press processing in one stroke of the press;

- the degree of deformation during crimping of the curved part is 0.7 ÷ 0.9 degree of deformation during drawing with thinning of the cylindrical part;

It is this that 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 thin-walled cases of variable cross-section by rotational and press machining, both individually and by combining them with high geometric shape accuracy and surface quality, saving metal and productivity due to the high stability of the forming process, as well as increasing the strength and operational reliability.

The specified technical result in the implementation of the invention is achieved by the fact that in the known method, including crimping the curved part of the tube billet and drawing another one, the feature is that steel tubes of a quiet grade with a tensile strength of 32 ÷ 65 kgf / mm ² are used as a billet, carry out rotational and or press machining of the workpiece with the formation of curvilinear, transitional and cylindrical parts with the axial direction of deformation; first, the transitional conical and curved the linear part with the wall thickness and tensile strength of the material is increasing, and the diameter decreasing towards the squeezable end, then in the opposite direction, the transition part is drawn with a variable wall thickness and cylindrical with thinning of the wall, while the transition part is formed with a cylindrical girdle and a conical section with the angle of inclination of the generatrix smaller by 1.5 ÷ 2.5 times the angle of inclination of the generatrix of the transitional part during its initial processing and at the end of processing, annealing is performed to reduce the stress and a temperature of 340 ÷ 360 ° C.

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

- use steel pipes of a calm grade as a workpiece - increase the operational properties of the shells: increase the toughness of the material at sub-zero temperatures to prevent cracking in the shell, for example, falling at sub-zero temperatures, which can lead to cracks and then an emergency;

- use as a billet of pipes with a tensile strength of 32 ÷ 65 (kgf / mm ² ) - expand the range of pipes used, that is, use hot-rolled pipes with a tensile strength of 32 kgf / mm ² and cold-rolled pipes with a tensile strength of 65 kgf / mm ² ;

- the shape of the workpieces by rotational and press processing to expand the technological capabilities of production in view of the fact that the combination of these methods gives the effect of increasing productivity, accuracy and quality of the processed surface, the use of the methods of rotational and press processing separately is effective, since the formation of the most complex transition parts of the workpieces, where corrugations and metal tightening occur with the formation of cracks and tears, they also perform both during rotational and press machining and geometrical sizes;

- the formation of curvilinear, transitional and cylindrical parts - to increase the accuracy of the geometric dimensions and the quality of the processed surface as a result of the fact that the formation between the curvilinear and cylindrical parts of the transitional part allows to eliminate corrugations, weights and cracks in this zone of the transition of one surface shape to another;

- the formation of curvilinear, transitional and cylindrical parts with an axial direction of deformation - to increase the mechanical properties of the metal of the bodies mainly in the axial direction (tensile strength, hardness, yield strength), since in the axial direction of deformation in the longitudinal section of the grain stock of the metal microstructure the deformation texture (see book A.P. Gulyaev. "Metallurgy." M., 1951, S. 130, 131) is an ellipse, the major axis oriented in the direction of deformation, i.e. in the direction of the axial movement of the deforming tool, the rollers during rotational crimping and rotational drawing, the punch with the workpiece in the matrix during compression processing; the increase in the mechanical properties of the metal in the axial direction is confirmed by the results of mechanical tensile tests of longitudinal and transverse samples; the physical meaning of the phenomenon of the preferential hardening of the metal in the axial direction of deformation can be represented in the form of displacement — the flow of an incompressible liquid in the form of droplets — polycrystal grains, which under the action of a deforming tool in the direction of deformation, i.e. in the direction of flow of the liquid-metal, they transform from droplets of a spherical shape into ellipsoids oriented by the major axis along the streamlines of the liquid-metal, i.e. the direction of deformation, and the orientation of the grains-ellipsoids does not depend on the direction of flow of the liquid-metal, the axis of the ellipsoids-grains are elongated along the streamlines of the metal in one or the other direction of the flow of metal; the number of deformed metal grains per unit cross-sectional area in the axial direction of deformation (by 1 mm ² ) is much larger than in the transverse direction, and since the largest axes of the grain have the greatest strength in the direction of deformation (see the book by A.P. Gulyaev "Metallurgy". M., 1951, p.130), then the mechanical properties of the workpiece metal in the axial direction of deformation are much higher than in other directions, therefore, the predominant hardening of the metal in the axial direction increases the operational properties the properties of the cases with small wall thicknesses of the cylindrical part while reducing weight; the test results of the shells by cyclic internal pressure showed that the preferential hardening of the metal in the axial direction (along the generatrix) increases the cyclic strength of the shells, the test results of the shells before final destruction by internal and external pressure showed that the cracks during fracture are shatterproof, are located along the cylindrical part and end in the curved part, which in an emergency protects the user (firefighters, submariners and rescuers) from injuries;

it should also be noted that the deformation texture, which determines the predominant mechanical properties in the axial direction along the forming workpiece and detected on longitudinal specimens during tensile tests, depends on the degree of deformation and the finish heat treatment of the bodies, so with a large degree of deformation of the cylindrical part of the workpiece, the mechanical properties of the metal this part is higher than in the curved and transitional parts, and the nature of the distribution of mechanical properties in the axial and transverse directions does not change nyashitsya; at a low temperature of the final heat treatment (low-temperature annealing), the texture of deformation and, therefore, the nature of the distribution of mechanical properties in all sections and directions (longitudinal and transverse) do not change;

- processing at first the transitional conical and curvilinear part in the direction of the crimped end, then in the opposite direction of the transition part with a variable wall thickness and cylindrical with thinning of the wall - to increase the accuracy of the geometric dimensions and the quality of the surface being treated, as this provides double processing of the transition part in different directions with a wall thickness that varies smoothly from curved to cylindrical, which eliminates corrugation in the transitional part, according to the applicant with this sequence of operations in the transitional part, a stress state is created with radial compressive and tensile stresses that impede the flow of metal from the mandrel in the transition zone to the cylindrical part and the flow of metal to the mandrel in the transition zone to the curved part; The mechanism of this effect is as follows:

a) when the transitional part is machined towards the crimp end in the bending zones of the generatrix, when passing from the cylinder to the cone, radial tensile stresses are formed, under the action of which the metal tends to flow from the mandrel, when passing from the cone to the curved part, radial compressive stresses arise, under which metal tends to mandrel, in the first case corrugations appear, in the other - folds;

b) when processing the transitional part in the opposite direction, the radial stresses change their sign in the opposite in the transition zones from the curved part to the transitional part and from the transitional to cylindrical, which eliminates the formation of corrugations and folds;

- processing of the curved part with a wall thickness and tensile strength of the material increasing, and decreasing in diameter towards the crimped end - to increase the operational properties of the housings - strength, reliability, service life and storage, as well as cyclic strength as a result of a joint increase in wall thickness and mechanical properties of the housing in the direction of the crimped end;

- the formation of the transitional part with a cylindrical girdle and a conical section during processing in the opposite direction - to improve the accuracy and quality of the surface being treated, since in this case the cylindrical girdle is stabilizing as a result of reducing the unevenness of deformation during the passage of deformation centers from the deforming tool - rollers or transition zone matrix curved outer and inner surfaces into a cylindrical - outer and inner; the physical meaning of this lies in the displacement of the inflection zones of the generatrix on the outer and inner surfaces, which eliminates the possibility of the formation of contraction, folds and cracks in these zones;

- the formation of a conical section of the transitional part of the workpiece in the opposite direction with an inclination angle of the generatrix smaller by 1.5 ÷ 2.5 times the angle of inclination of the transitional part at its initial shaping, - to increase the stability of the shaping process as a result of a gradual two-transition processing of this part, first get transitional part with a large angle when it is processed in the direction of the crimped end, then in the opposite direction with a smaller angle; the angle of inclination of the generatrix, less than 1.5 ÷ 2.5 times the angle of inclination during initial processing, is optimal, determined experimentally, for values that go beyond these limits in one direction or another, corrugations or braces and cracks with a separation of the cylindrical parts; the applicants believe that the positive effect of this treatment of the transitional part is also a change in the nature of the stress state of the metal when processing in the opposite direction, in the bending zones of the generatrix there are "radial" stresses "opposite in sign to the stresses during the initial processing of the transitional part towards the crimped end, which prevent the occurrence of corrugations, hooks and cracks;

- performing at the end of the annealing processing a reducing voltage at a temperature of 340 ÷ 360 ° C - remove internal stresses in the metal of the casing while maintaining high mechanical properties - (ultimate strength). The temperature is 340–360 ° С below 0.4 Т _pl = 0.4 × 1350 ° = 540 ° С; therefore, recrystallization (grain growth with a decrease in tensile strength) does not occur (see the book by A.N. Gulyaev. "Metallurgy". M., 1951, Fig. 109, p. 131); as a result of low-temperature annealing at this temperature, the deformation texture is preserved i.e. the direction and dimensions of the deformed grains of the microstructure of the metal are preserved, therefore, the mechanical properties in various sections and directions (longitudinal and transverse) are preserved.

Signs characterizing the invention in specific forms of execution, allow, in particular, due to:

- crimping the curvilinear part with a wall thickness at the crimped end equal to 1.1 ÷ 1.5 of the wall thickness of the workpiece, - increase the stability of the processes of forming the workpiece both by rotary crimping and crimping by pressing, since the crimping process is characterized by an increase in wall thickness in the direction of the crimped end face, that is, in the direction of decreasing diameter, and this process is most stable when the wall thickness of the pressed end is within 1.1 ÷ 1.5 of the wall thickness of the workpiece at the beginning of crimping; when the workpiece thickness is more than 1.5, the workpiece wall thickness increases the number of transitions, and when less than 1.1 corrugations and cracks occur at the crimped end as a result of the restriction of the radial metal flow;

- performing crimping of the curved part with a tensile strength of the material in the direction of the crimped end, varying according to:

where σ _In (kgf / mm ² ) is the current value of tensile strength,

σ _{In ref} (kgf / mm ² ) - the initial value of the tensile strength,

ε (%) is the degree of deformation of the crimp,

α ° - the current value of the cone angle of the curved part;

- to ensure a smooth increase in the tensile strength from the beginning of the curved part to the crimped end, depending on the degree of deformation and the angle of inclination of the generatrix, that is, the taper angle of the curved surface, this formula is determined experimentally in the process of developing a method for manufacturing cases and in combination with a wall thickness that gradually increases to crimp end, provides high operational reliability of the housing, strength, service life and storage, cyclic strength;

the formation of the transitional part of the workpiece when drawing with a cylindrical girdle with a length not exceeding the wall thickness of the workpiece, to increase the stability of the forming process, since when the girdle length is more than the wall thickness, the body weight increases, and if the girdle length is too short, close to zero, the stability of the forming process decreases due to the approach of the inflection lines forming on the outer and inner surfaces, which increases the unevenness of deformation in the interface between the curved and transitional parts and increases the likelihood of corrugation;

- the formation of the transitional part of the workpiece during the hood with thinning with the wall thickness of the conical section, decreasing in the direction from the curved part to the cylindrical, - to increase the stability of the forming process, as a result of the fact that the wall thickness of the conical section gradually decreases from the cylindrical section in the direction from curved to cylindrical parts, which ensures a smooth increase in strain along the metal flow lines (along the generatrix of the conical section of the mandrel) and to eliminate the formation of corrugations, crack n and detachment from the curvilinear cylindrical portion;

- changing the workpiece at first by rotational crimping of the transitional and curvilinear parts, and then by drawing it with thinning of the transitional and cylindrical parts by press processing - to expand the technological capabilities of the production of casings and increase productivity, accuracy and quality of surface treatment, the likelihood of waviness, roughness and other small defects is reduced;

- changing the workpiece by press machining - first by crimping curvilinear, then by distributing the transitional, cylindrical and curvilinear parts, and then by a rotary hood with thinning the walls of the transitional and cylindrical parts - expand the technological capabilities of the production of casings, increase productivity, accuracy and quality of the processed surface, since the combination of the press and rotary processing gives a new quality to the proposed method, due to the fact that the press processing - crimping, distribution, drawing makes I have a high strain rate, which increases the surface cleanliness, and rotational processing — rotational drawing — rotational crimping is performed with local deformation centers at a lower speed, which allows us to process transitional mating zones having bends forming with a smooth increase in deformation along the metal flow lines along the mandrel, and as a result, eliminate corrugation and tightening, as well as cracks in this transitional part of the workpiece; in this way, a high surface finish is obtained by pressing processing, a high accuracy of geometric shape is obtained by rotary processing, and their combination in one sequence or another gives both high accuracy of geometric dimensions and high quality of the processed surface;

- distribution of the cylindrical part of the workpiece with a degree of deformation equal to the degree of deformation of the diameter change during drawing with thinning of the wall of the same part by pressing, - to ensure the stability of the process of forming the cylindrical part, since when distributing in the workpiece, compressive radial stresses are realized, which during subsequent drawing with thinning prevent the increase in the outer diameter of the cylindrical part after passing the workpiece through the matrix, that is, compensate for radial tensile stresses and increase in the diameter of the cylindrical part; the equality of the degrees of deformation of the change in diameter during distribution and extraction is due to the final dimensions of the inner and outer surfaces of the cylindrical part without additional mechanical processing, which increases the utilization of the metal;

- crimping of the curved part with a degree of deformation of 0.7 ÷ 0.9 of the degree of deformation during drawing with thinning of the cylindrical part, - to increase the productivity of the process of forming the workpiece in both rotational and press machining, and with their combinations, this ratio is optimal, determined experimental testing, so when the degree of crimping is more than 0.9, the degree of deformation during drawing with thinning increases the number of crimping operations, and if less than 0.7, an additional increase in the number of drawing x operations, which increases the complexity of manufacturing hulls;

- performing crimping curvilinear and distributing the cylindrical and transitional parts by pressing for one stroke of the press - to increase the productivity of manufacturing cases by combining two operations in one.

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."

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 enclosures of variable cross-section, steel tubes of a quiet grade with a tensile strength of 32 ÷ 65 kgf / mm ² are used as a workpiece, forming is carried out by rotational and or press processing of the workpiece with the formation of curved, transitional and cylindrical parts , with the axial direction of deformation, first the transitional conical and curvilinear parts with a wall thickness and tensile strength of the material are increased, and I decrease the diameter in the direction to the crimped end, then in the opposite direction - transitional with a variable wall thickness and cylindrical with thinning of the wall, while the transitional part is formed with a cylindrical girdle and a conical section with an inclination angle of the generatrix less than 1.5 ÷ 2.5 times the angle the inclination of the generatrix of the transitional part during its initial processing, and at the end of the processing, annealing is performed to reduce stresses at a temperature of 340 ÷ 360 ° C.

The invention is illustrated by drawings, where figure 1 shows the process of rotational crimping of the transitional and curvilinear parts, figure 2 - the process of rotational drawing with thinning the wall of the transitional and cylindrical parts, figure 3 - rotational crimping and rotational drawing with thinning of the transitional and cylindrical parts in an enlarged view, in Fig. 4 - crimping of the curved part by press processing, in Fig. 5 - distribution of the cylindrical, curvilinear and transitional parts by pressing treatment, in Fig. 6 - hood with thinning transitional and cylindrical ith parts by pressing, in Fig. 7 - crimping, distributing and drawing out with thinning of the transitional and cylindrical parts by extrusion, in Fig. 8 - crimping curvilinear and distributing the transitional and cylindrical parts by pressing.

- (мм) длина начала обработки от обжимаемого торца до линии врезания.Figure 1 shows: blank 1 in the initial state with a diameter D _zag (mm), thickness t _zag (mm), blank 2 after rotational crimping, mandrel 3, deforming rollers 4 at the beginning and end of crimping, axial feed direction F ₁ ( mm / min), the direction of rotation of the workpiece with mandrel S ₁ (min ^-1 ), the cylindrical part of the workpiece of length L _C (mm), the transition part of length L ₁ (mm) with an angle of inclination of the generatrix β ° and the curved part of length L ₀ (mm ) with a taper angle α °, thickness t ₀ (mm) at the beginning and t ₁ (mm) at the end of crimping, with a diameter at the beginning of crimping D ₀ (mm) and at the end of crimping d (mm),

- (mm) the length of the start of processing from the crimped end to the incision line.

Figure 2 shows the workpiece 2 in the initial state, obtained by rotational crimping, the workpiece 5 after rotational drawing with thinning of the wall with the length of the cylindrical part L _C2 (mm), with the wall thickness of the cylindrical part t _C (mm), with the length of the curved part L ₀ (mm), with the thickness of the curved part at the beginning t ₀ (mm), with the thickness of the curved part at the end t ₁ (mm), with the diameter of the curved part at the beginning D ₀ (mm) and at the end d (mm), with the transition length parts L ₂ (mm), with the length of the cylindrical girdle of the transitional part L _C (mm), with the length of the conical section of the transition part of L _K (mm), with the angle of inclination of the generatrix of the conical section of the transition part γ °, the direction of axial feed F ₂ (mm / min), the direction of rotation of the workpiece S ₂ (min ^-1 ), rollers 4, mandrel 6.

In Fig. 3, blank 2 in the initial state after rotational crimping with the initial wall thickness t _zag , with the wall thickness at the beginning of the curved part t ₀ (mm), with a diameter at the beginning of the curved part D ₀ (mm), with the length of the transition part L ₁ (mm), with the angle of inclination of the generatrix of the transitional part β ° (AA ₁ B ₁ B), the workpiece 5 after the rotation hood with thinning with a wall thickness at the beginning of the rotation hood t ₀ (mm) equal to the wall thickness at the beginning of the rotational crimp t ₀ ( mm) with a cylindrical portion the wall thickness t _c (mm), the transition portion (AA ₁ BB DD _{1 1} CC _1), with the length of cylinder ndricheskogo girdle transition portion L _n (mm), a length of the tapered portion of the transition portion L _K (mm), a length of the transition portion L ₂ (mm), a tilt angle of the generatrix of the conical portion of the transition portion γ ° (DD ₁ CC _1), the mandrel 6, the deforming rollers 4 at the beginning of the rotational drawing of the transition part and during the rotational drawing of the cylindrical part.

Figure 4 shows: the blank 1 in the initial state with the wall thickness t _zag (mm) and the length L _zag (mm), the blank 7 after crimping with the wall thickness at the beginning of the curved part t ₀ (mm) and at the end t ₁ (mm ), with a diameter at the beginning of the curvilinear part D ₀ (mm) and at the end d ₁ (mm), with the length of the curvilinear part L ₀ (mm) and the cylindrical part L _c (mm), punch 8 with the direction of axial movement F ₁ (mm / min), the matrix 9, the guide sleeve 10 and the ejector 11.

Figure 5 shows: the blank 7 after crimping in the initial state with a wall thickness of 6 at the beginning of the curved part t ₀ (mm) and a diameter of D ₀ (mm), with a wall thickness at the end of the curved part of t ₁ (mm) and a diameter of d ₁ ( mm), with the length of the cylindrical part L _c (mm), with the length of the curved part L ₀ (mm), workpiece 2 after distribution with the length of the curved part L ₀ (mm), with a diameter at the beginning of D ₀ (mm) and at the end of the curved part d ₂ (mm) with a wall thickness at the beginning t ₀ (mm) and at the end t ₁ (mm) of the curved part, with the length of the transition part L ₁ (mm), with the length of the cylindrical part L _C1 (mm), with an inclination angle of the generatrix of the transitional part β °, the punch 12 with the direction of axial movement F ₁ (mm / min), the matrix 13, the stripper 14.

Figure 6 shows: the blank 1 in the initial state at the start of the hood with thinning, the blank 5 during the hood, the punch 15 in two positions - at the beginning of the hood and during the hood, the hood 16, the puller 17, the direction of axial movement of the punch with the workpiece during the drawing process F ₂ (mm / min), L ₁ (mm) - the length of the transition section before the hood or also after distribution (Fig. 5), L ₂ (mm) - the length of the transition part after drawing with thinning, L _p (mm) - the length of the cylindrical belt of the transitional part after drawing, L _K (mm) - the length of the conical section ka of the transitional part after drawing, t _zag (mm) is the wall thickness of the cylindrical part before drawing, t _c (mm) is the wall thickness of the cylindrical part after drawing with thinning, ΔD (mm) is the amount of change in the inner diameter after distribution and the outer diameter after drawing with thinning, β ° is the angle of inclination of the generatrix of the transitional part after distribution and before drawing, γ ° is the angle of inclination of the generatrix of the conical section of the transitional part after drawing. D ₀ (mm) is the diameter of the beginning of the curved part, t ₀ (mm) is the wall thickness of the beginning of the curved part.

Figure 7 shows the transitional part of the workpiece on an enlarged scale at the start and during the drawing process with thinning with the workpiece 2 before and the workpiece 3 during the drawing process with thinning, punch 15 and die 16 in two positions - at the beginning and during the drawing with thinning , the transitional part (AA ₁ B ₁ B) after distribution and before drawing out with thinning, L ₁ (mm) - the length of the transitional part after distribution before drawing out with thinning, L ₂ (mm) - the length of the transitional part after drawing out with thinning, L ₂ = L _p + L _K , that is, the length of the transitional part after drawing with thinning folds extend from the lengths of the cylindrical girdle and the conical section. Transitional part after exhaust with thinning - AA ₁ D ₁ C ₁ CD. Angles β ° and γ ° are the inclination angles of the generatrix of the transitional part before and after drawing, t _zag (mm) and t _C (mm) are the wall thicknesses of the cylindrical part before and after drawing, D ₀ (mm) is the diameter at the beginning of the curved part, t ₀ (mm) - wall thickness at the beginning of the curved part.

(мм) - длина обжатой криволинейной части, β° - угол наклона образующей переходной части.On Fig depicts the process of crimping and distribution with the position of the workpiece 1 and 2 before the start of the process and in its final stage, which also shows the punch 18, the die 19, the puller 14, the ejector 11, the direction of axial movement of the punch and the workpiece - F ₁ (mm / min), L _zag (mm) and t _zag (mm) the length and thickness of the workpiece before crimping and distribution, t ₀ (mm) and t ₁ (mm) - wall thickness at the beginning and end of the curved part, d (mm) - the outer diameter of the compressed workpiece at the end of the curved part, L ₁ (mm) is the length of the transition part,

(mm) is the length of the crimped curved part, β ° is the angle of inclination of the generatrix of the transition part.

The above-described method of manufacturing enclosures is as follows.

The initial billet 1 (Fig. 1) is made of steel pipes of a calm grade of steel, hot-rolled or cold-rolled, with a tensile strength of 32 ÷ 65 kgf / mm ² , by cutting pipes into billets and machining.

от обжимаемого торца в направлении к обжимаемому торцу, вначале обжимают переходную коническую часть длиной L₁ (мм) с углом наклона образующей β и толщиной стенки t₀ (мм), затем обжимают криволинейную часть длиной L₀ (мм) с толщиной стенки, возрастающей от t₀ (мм) в начале криволинейной части, до t₁ (мм) в конце криволинейной части, с диаметром, уменьшающимся от диаметра D₀ (мм) в начале до диаметра d (мм) в конце криволинейной части, с углом наклона касательной к криволинейной поверхности α°, также возрастающим от начала обработки к концу криволинейной поверхности, с пределом прочности, возрастающим в том же направлении.In the manufacture of cases by methods of rotational processing, the workpiece 1 is mounted on the mandrel 3, mounted on the spindle of the press-rolling machine, fixed on the mandrel with a clamping device, and rotational crimping by deforming rollers 4 is carried out starting from the cylindrical part of the workpiece of length L _C (mm) at a distance

from the crimped end toward the crimped end, first the transitional conical part is pressed with a length of L ₁ (mm) with the inclination angle of the generatrix β and the wall thickness t ₀ (mm), then the curved part is pressed with the length L ₀ (mm) with the wall thickness increasing from t ₀ (mm) at the beginning of the curvilinear part, up to t ₁ (mm) at the end of the curvilinear part, with a diameter decreasing from the diameter D ₀ (mm) at the beginning to a diameter d (mm) at the end of the curvilinear part, with an angle of inclination of the tangent to curved surface α °, also increasing from the beginning of processing to the end of the curved surface, with a tensile strength increasing in the same direction.

The direction of the axial feed of the rollers - F ₁ (mm / min) - to the crimped end.

Then, in the direction opposite to the direction of crimping, perform a rotational hood with thinning the walls of the transition and cylindrical parts (Fig.2, 3).

First, the transition part is treated with a length of L ₂ (mm) with a cylindrical belt of length L _p (mm), a thickness of t ₀ (mm) and a conical section of length L _K (mm) with a wall thickness decreasing in the direction from the curved part to the cylindrical part from t ₀ (mm) to t _c (mm).

Then, a cylindrical part is rotationally drawn with a wall thinning with a wall thickness t _c (mm) with a strain degree ε _c with a cylindrical part length L _c2 (mm).

The direction of the axial feed of the rollers F ₂ (mm / min) with a rotary hood (Fig. 2) is opposite to the direction of the feed of the rollers with a rotary crimp F ₁ (Fig. 1).

In the manufacture of cases by pressing methods and combined press-rotary and rotary-press (Fig.4 ÷ 8) the sequence of operations is as follows.

First, by machining (Fig. 4), the curved part is formed by crimping the workpiece 1 with a punch 8 in the matrix 9. The workpiece 1 is installed in the initial position in the guide 10. The workpiece in the initial position has dimensions t _zag (mm) - wall thickness and L _zag (mm) - the length of the workpiece. After crimping, the workpiece 7 has: the length of the curved part L ₀ (mm), the wall thickness at the beginning of the curved part t ₀ (mm), the wall thickness at the end of the curved part at the crimped end t ₁ (mm), the length of the cylindrical part L _c (mm) , the diameter of the curved part at its beginning D ₀ (mm) and at the end of the crimped end d ₁ (mm).

Then the workpiece 7 (Fig. 5) is distributed by a punch 12 in the matrix 13 with the formation of a cylindrical part of length L _C1 (mm), a transition part of L ₁ (mm) with an inclination angle of the generatrix of β °, a curved part of length L ₀ (mm) with a thickness walls t ₀ (mm) at the beginning, t ₁ (mm) - at the end of the curved part at the crimped end.

The thickness of the workpiece t _zag (mm) and t ₁ (mm) vary slightly, and the dimensions D ₀ (mm) and t ₀ (mm) at the beginning of the curved part are not changed.

The internal profile of the curved part is final without additional machining, while the diameter d ₁ (mm) increases to d ₂ (mm), the wall thickness t ₁ (mm) practically does not change.

With the reverse stroke of the press, the workpiece 2 is removed from the punch 12 by the puller 14.

Next, the workpiece 2 (Fig.6), the punch 15 is subjected to a hood with thinning by pressing processing in a matrix 16 from a thickness t _zag (mm) to a thickness t _c (mm), at the same time, at the beginning a transition part with dimensions varying with L ₁ (mm) is obtained to L ₂ (mm), from β ° to γ °, from t ₀ (mm) to t _c (mm) along the length L _K (mm), and with a cylindrical belt of length L _K (mm) with a wall thickness t ₀ ( mm).

The diameter at the beginning of the curved part D ₀ (mm) and the wall thickness of the beginning of the curved part t ₀ (mm) are not changed.

After the hood at the reverse stroke, the workpiece 5 is removed from the punch 15 puller 17.

The process flow diagram of the transitional part of the workpiece (Fig. 3, Fig. 7) during rotational, press, combined press-rotary and rotary-press machining is, first, crimping or distributing part of the workpiece ABB ₁ A _{1 of} length L ₁ with an angle of inclination forming β ° in the direction of the crimped end and then drawing with thinning of the same part in the opposite direction with the formation of a cylindrical belt ADD ₁ A _{1 of} length L _p (mm) and a conical section of DCC ₁ D _{1 of} length L _K (mm) with a slope of the generatrix γ ° and total length L ₂ (mm).

Combined press-rotary processing (FIGS. 4, 5, 8 and FIG. 2) and rotational press-processing (FIG. 1 and FIG. 6) processings produce bodies with curvilinear, transitional and cylindrical parts according to the same technological scheme: 1 ) when the processing direction to the crimped end is first obtained, the curvilinear and transitional parts, 2) in the opposite direction of processing from the curvilinear part to the cylindrical, the transitional and cylindrical parts are obtained.

Thus, with any of the above processing, the transition part (Fig. 3, Fig. 7) is obtained with the same geometric dimensions and the same sequence of operations of forming, the cylindrical part is obtained (Fig. 2, Fig. 6) also with those with the same dimensions and in the same sequence, the curvilinear part is obtained either by dispensing (Fig. 5) or crimping (Fig. 1, Fig. 4, Fig. 8) also with the same dimensions and in the same sequence.

In addition, it is possible to obtain a curved part with the same dimensions of the outer surface by crimping (Fig. 4) by compression treatment, and the cylindrical part by mechanical turning on the inner surface.

The combined operation of the distribution and crimping (Fig) is performed in one stroke of the press. A blank 1 with a length L _zag (mm) and a thickness t _zag (mm) is installed in the guide part of the matrix 19 and the punch 18 distributes a cylindrical part with a length L _c (mm), a transition part with a length L ₁ (mm) and crimping a curved part with a length L ₀ (mm), diameters D ₀ (mm) at the beginning and d (mm) at the end of the curved part, wall thickness t ₀ (mm) at the beginning and t ₁ (mm) at the end of the curved part.

In the reverse stroke of the press, the workpiece is removed with a puller 14 from the punch 18 or ejector 11 from the matrix 19.

In the final stage of the technological process, annealing is performed at a temperature of 340 ÷ 360 ° C in electric furnaces with holding at a metal temperature of 1.0 ÷ 2 hours.

Example 1

The billet from hot-rolled pipes ⌀133 × 14 steel 10 of calm grade with the initial mechanical properties - tensile strength 32 ÷ 38 kgf / mm ² after cutting the pipes into billets, calibrations on the inner surface are subjected to recrystallization annealing at a temperature of 630 ÷ 680 ° C, mechanical (turning ) processing on the outer and inner surfaces.

- определяют из равенства объемов готовой криволинейной части и обрабатываемой части заготовки.Then the tube stock with a diameter D _zag = 130 mm with a wall thickness t _Z = 8 mm and a length L _Z = 550 mm is mounted on a mandrel fixed in the spindle of a press-rolling machine, fixed from one of the ends by a clamping device, and subjected to rotational crimping (figure 1) in the direction of the crimp end. Start of processing - distance from the end to the cutting line

- determined from the equality of the volumes of the finished curved part and the processed part of the workpiece.

The direction of crimping F ₁ (mm / min) from the beginning of processing to the crimped end (from the clamped end) is the direction of the axial feed of the rollers.

In the process of rotational crimping, at first, a conical transitional part with a length of L ₁ = 30 mm is formed with an inclination angle of the generatrix β = 4 °, then a curvilinear part with a taper (twice the angle of inclination of the tangent to the curved surface) α ° from 4 ° at the beginning of the curved surface to 20 ° at the pressed end - at the end of a curved surface, length L ₀ = 227.2 mm, diameter at the beginning of the curved part D ₀ = 121 mm and at the end of the curved part d = 76 mm, wall thickness at the beginning t ₀ = 6 mm and at the end curvilinear part of the pressed end t = 8 mm

The degree of crimping deformation increases from 0% to ε ₀ % at the end of the curved part:

Crimping is carried out with a tensile strength of the material increasing towards the crimped end. At the beginning of crimping at the moment the rollers touch the workpiece, the tensile strength σ _{B ref} = 35 kgf / mm ² and increases towards the end of the curved part according to the formula:

where ε% is the degree of deformation of the crimp,

D _tech - the current value of the diameter,

α ° - taper angle, current value,

σ _{in ref} (kgf / mm ² ) is the ultimate strength in the initial state.

The values of tensile strength in the direction of the crimped end at distances from the beginning of crimping 1 mm, 30 mm, 144 mm, 257.2 mm are shown in table No. 1.

Table number 1. No. p / p Length α ° D _zag (mm) D _tech (mm) ε% σ _in (kgf / mm ² ) one 0 ~ 1 130 0 0 35 2 one 8 130 128.6 1,08 37.7 3 thirty 8 130 121 6.9 52.3 four 144 10 130 111.6 14.15 63.8 5 257 twenty 130 76 41.5 74.9

An analysis of the values of the tensile strength depending on the length, taper angle, and degree of deformation (Table 1) shows that the tensile strength of the material in the direction of the crimped end smoothly increases to the maximum value of the compressed end in the axial direction (on longitudinal samples) - (74, 9 kgf / mm ² ) according to the above formula, which corresponds to the proposed claims and the requirements of technical documentation.

These results are confirmed by the results of mechanical tests of samples cut from the zone adjacent to the crimped end.

Thus, an increase in the tensile strength simultaneously with an increase in the wall thickness to the crimped end during the process of forming - crimping increases the operational reliability of the cases, strength, service life, shelf life and cyclic strength.

After that, perform a rotational hood with thinning the walls of the transition and cylindrical parts in the opposite direction (figure 2) by deforming rollers starting from the curved part, while the curved part remains unchanged.

The transition part is obtained with a length L ₁ = 71 mm with a cylindrical section with a length L _p = 7.8 mm (less than t _zag = 8 mm), which corresponds to the claims (L _p <t _zag according to the claims), and wall thickness t ₀ = 6 mm, with a conical section of length L _K = 63 mm and an angle of inclination of the generatrix γ = 2 °.

в сечении A-A₁ (фиг.3) до

предел прочности (на продольных образцах) возрастает от 60 кг/мм² в начале переходного участка до 80 кг/мм² в конце этого участка в сечении С-С₁ (фиг.3) и остается без изменения на всем цилиндрическом участке.The degree of deformation of the transitional part (figure 2, 3) increases over a length L ₁ = 71 mm from

section AA ₁ (figure 3) to

the tensile strength (on longitudinal samples) increases from 60 kg / mm ² at the beginning of the transition section to 80 kg / mm ² at the end of this section in section CC ₁ (Fig. 3) and remains unchanged throughout the cylindrical section.

The tensile strength values on the transverse samples at the beginning and end of the curved and transitional sections, as well as the cylindrical section, are 10-15% less than the values on the longitudinal samples.

The cylindrical part is obtained with a length of at least L _C = 619 mm, with a wall thickness L _C = 4 mm.

The degree of deformation during the rotational drawing of the cylindrical part during thinning of the wall from t ₀ = 8.0 mm to 4 mm:

The angle of inclination of the generatrix during the extraction of the transitional part (γ = 2 °) is 2.0 times smaller than the angle of inclination of the generatrix of the transitional part during crimping (β = 4 °), which corresponds to the claims.

The ratio of the degree of deformation of the crimp and the hood is set as follows. The degree of deformation during crimping of the curved part (ε ₀ = 41.5%) is 0.83 degrees of deformation during stretching (ε _c = 50%) of the cylindrical part, which corresponds to the claims.

At the end of the treatment, annealing is performed to reduce stresses at a temperature of 340 ÷ 360 ° C in an electric furnace with exposure at this temperature for 1 ÷ 2 hours, then air cooling to relieve internal stresses and preserve the deformation texture and mechanical properties both in magnitude and and the nature of the distribution of the plots and in the longitudinal and transverse directions.

In the combined rotary press (Fig. 1, Fig. 6) and press-rotary (Fig. 4, Fig. 5, Fig. 8, Fig. 2) treatments, the rotational crimping and the rotational hood are performed in the same way as in the above example 1 .

Example 2

заготовку диаметром 122 мм, длиной L_з=630 мм устанавливают в направляющую матрицы отожженной частью вниз и подвергают ее обжиму и раздаче (фиг.8) с получением криволинейной части в начале D₀=121 мм и в конце у обжатого торца d=74,5 мм с диаметром внутренней поверхности 112,5 мм, с толщиной стенки t_з=6 мм, t₀=6 мм, t₁=6,6 мм, L₁=30 мм, β=4°.Billet from cold-rolled pipes ⌀122 × 6 steel 10 of a quiet grade with an initial tensile strength of the material σ _in = 60 ÷ 65 kgf / mm ² after cutting pipes into billets and recrystallization annealing (at a temperature of 620 ÷ 650 ° C) of one part of the billet length

a workpiece with a diameter of 122 mm, length L _s = 630 mm is installed in the matrix guide with the annealed part down and subjected to crimping and distribution (Fig. 8) to obtain a curved part at the beginning D ₀ = 121 mm and at the end at the crimped end d = 74, 5 mm with an inner surface diameter of 112.5 mm, with a wall thickness t _s = 6 mm, t ₀ = 6 mm, t ₁ = 6.6 mm, L ₁ = 30 mm, β = 4 °.

Next, the preform is subjected to recrystallization annealing of the cylindrical part at a temperature of 620 ÷ 650 ° C and hood with thinning (Fig.6) to obtain the same geometric dimensions of the transition and cylindrical parts and the same mechanical properties (see example 1).

At the end of the processing, annealing is performed to reduce stresses at a temperature of 340 ÷ 360 ° C, which also corresponds to the claims.

When distributing (Fig. 5, Fig. 8) and extracting the cylindrical part (Fig. 6), the degree of deformation of the inner diameter when distributing ΔD (mm) is equal to the degree of deformation of the outer diameter ΔD (mm) during drawing with thinning, which corresponds to the claims and is 112-109 = 3.0 (mm) during distribution, 124-121 = 3.0 (mm) during extraction with thinning, where ⌀109 mm is the internal diameter of the workpiece before distribution, ⌀112 mm is the internal diameter of the workpiece after distribution before extraction with thinning, ⌀124 mm - the outer diameter of the workpiece before the hood, ⌀121 mm - the outer diameter of the workpiece after the hood with thinning.

In combined rotary-press (Fig. 1, Fig. 6) and press-rotary (Fig. 4, Fig. 5, Fig. 8, Fig. 2) treatments, the hood with thinning, crimping and distribution are performed in the same way as in the above example 2.

The combined manufacturing method is also the production of bodies by pressing - crimping the curved part (figure 4) and then machining - (turning) the inner surface of the cylindrical and transition parts (figure 2), using используют122 × 6 mm cold rolled pipes (example 2) steel 10 calm brand. When crimping (figure 4) receive a curved part with the same dimensions and mechanical properties. The cylindrical part on the inner surface with the same dimensions (figure 2) is obtained by turning on a lathe.

The implementation of the method of manufacturing thin-walled enclosures of variable cross-section in accordance with the invention enables the manufacture of casings with high accuracy of geometric dimensions, surface quality, high performance with high metal utilization, strength and operational reliability.

The invention can be used in the manufacture of thin-walled cases of variable cross-section of pressure vessels and shells of various sizes.

The indicated positive effect is confirmed by tests of experimental batches of cases made by this method.

Currently, technical documentation has been developed, tests have been carried out, serial production of products by the proposed method is planned.

Claims (10)

1. A method of manufacturing thin-walled enclosures of variable cross section, comprising crimping one part of the pipe billet and drawing another, characterized in that pipes of calm grade with a tensile strength of 32 ÷ 65 kgf / mm ² are used as the billet, rotational and / or pressing the workpiece with the formation of curved, transitional and cylindrical parts with the axial direction of deformation, and at first they process the transitional conical and curved parts with a wall thickness and the strength limit of the material is increasing, and the diameter is decreasing in the direction of the crimped end, then in the opposite direction is the transition part with a variable wall thickness and cylindrical with thinning of the wall, while the transition part is formed with a cylindrical girdle and a conical section with an inclination angle of the generatrix smaller than 1.5 ÷ 2.5 times the angle of inclination of the generatrix of the transitional part during its initial processing, and at the end of processing, annealing is performed to reduce stresses at a temperature of 340 ÷ 360 ° С. 2. The method according to claim 1, characterized in that the crimping of the curved part is performed with a wall thickness at the crimped end equal to 1.1 ÷ 1.5 of the wall thickness of the workpiece. 3. The method according to claim 1, characterized in that the crimping of the transitional and curvilinear parts is performed with a tensile strength of the material in the direction of decreasing the diameter to the end, varying depending

where σ _in (kgf / mm ² ) is the current value of tensile strength;
σ _in.ex (kgf / mm ² ) is the initial value of the tensile strength;
ε (%) is the degree of crimping strain;
α ° - the current value of the angle of taper. 4. The method according to claim 1, characterized in that the cylindrical girdle of the transitional part of the workpiece during drawing is formed with a length not exceeding the wall thickness of the workpiece. 5. The method according to claim 1, characterized in that the transitional part of the workpiece during the hood with thinning is formed with the wall thickness of the conical section, decreasing in the direction from the curved part to the cylindrical. 6. The method according to claim 1, characterized in that the shape of the workpiece is carried out first by rotational crimping of the transitional and curvilinear parts, and then by extraction with thinning of the transitional and cylindrical parts by pressing. 7. The method according to claim 1, characterized in that the blank is shaped by pressing - first crimping curvilinear, then distributing the transitional and cylindrical parts, and then a rotational hood with thinning the wall of the transitional and cylindrical parts. 8. The method according to claim 1, characterized in that the degree of deformation of the cylindrical part of the workpiece during distribution is equal to the degree of deformation of the change in diameter when drawing with thinning the wall of the same part. 9. The method according to claim 1, characterized in that the crimp is curved and the distribution of the cylindrical and transitional parts of the workpieces is performed by pressing in one stroke of the press. 10. The method according to claim 1, characterized in that the degree of deformation during crimping of the curvilinear part is 0.7 ÷ 0.9 degree of deformation during drawing with the thinning of the cylindrical part.

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