RU2558814C1 - Thin-walled shell manufacturing method - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: thick-walled hollow work piece is fabricated. Its rotational drawing is performed in two operations: in preliminary one for semi-finished product, and in a final for thin-walled shell with formation on external surface of the compensator shell, heat treatment for removal of tension between preliminary and final operations of the rotational drawing and final processing of the shell. The semi-finished product is deformed along the whole length, and after processing of the thin-walled cylindrical section of the shell during final operation of the rotational drawing process the compensator section is processed which is finished by formation on external surface of the conic section of interface with the thick-walled section of the cover with the slope angle of the generatrix of the conic section 8-20 degrees.

EFFECT: geometrical accuracy of the sizes of the shell is improved due to reduction of thickness variability at the compensator section.

2 cl, 3 dwg

Description

The invention relates to the processing of metals by pressure and can be used in the manufacture of thin-walled shells for special purposes.

A known method of manufacturing on a three roller rolling machine a thin-walled shell made of martensitic steel in the form of a small and a large cylinder, interconnected by a truncated cone, including the manufacture of a thick-walled hollow billet, the first (preliminary) operation of the rotational drawing of a semi-finished product with the formation of a cylindrical section, the heat treatment of a semi-finished product for stress relieving, the second (final) operation of rotational drawing with the formation of thin-walled cylindrical part Single shell and compensator rotary compression inside the cylindrical portion of the shell adjacent to the end face of the large cylinder and final processing. The method is adopted as a prototype (see RTM 3-1674-85 p. 175-190).

The disadvantages of the prototype are:

1. It is impossible to produce a cylindrical section of a semi-finished product with a volume equal to the volume of a thin-walled cylindrical section of the shell in preliminary and final operations of rotational drawing, since this requires the manufacture of a semi-finished product and a shell in nominal dimensions without the use of tolerances; therefore, a step technological compensator with a wall thickness after a preliminary operation of rotational drawing in the range from 2.3t to 7.5t is left behind a thin-walled cylindrical section of the shell, where t is the thickness of the thin-walled cylindrical section shell. If the compensator is not left, there is a sharp change in the degree and force of deformation, leading to a change in excess of the tolerance of the geometric dimensions or rupture of the shell. After receiving a step-by-step technological compensator in the process of rotational drawing, it is processed by cutting to reduce the mass of the casing and to obtain smooth coupling with the thick-walled section of the casing, due to the ovality of the casing and errors during processing by the section of the compensator, as a rule, a greater thickness than during rotational hood of a thin-walled cylindrical section of the shell.

2. The section of the shell between the end of the rolled surface and the beginning of the compressed section remains undeformed with the roughness of the surfaces of the original sheet.

The present invention solves the problem of improving the quality of the shell and reducing the cost of manufacturing.

The technical result obtained by the implementation of the invention is to increase the geometric accuracy of the shell by reducing the thickness difference in the section of the compensator, reducing the roughness of the inner diameter along the entire length of the shell and reducing costs in the manufacture of the shell.

The specified technical result is achieved by the fact that in the method of manufacturing a thin-walled shell, including the manufacture of a thick-walled hollow billet, the rotational drawing of a thick-walled hollow billet in two operations, while in the preliminary operation the hollow billet is deformed along the entire length to obtain a semi-finished product with a thick-walled end section adjacent to the open end face, and in the final operation of the rotary hood get a thin-walled shell with an end thick-walled section of the pair and the compensation section Atomator, it is new that the compensator section is formed in the form of a cylindrical section adjacent to the conical section of the interface, conjugated with the conical section of the shell, while the connection sections are conical with an inclination angle of the generatrix of 8-20 degrees, heat treatment is performed to relieve stresses between the preliminary and final operations of the rotary hood and the final processing of the shell.

When a rotational hood with a degree of deformation close to the limit, the compensator section is performed in two passes, the first to set the volume of the compensator, and the second to the specified dimensions.

The rotary hood of the semi-finished product along the entire length reduces the roughness of the inner surface of the shell relative to the original.

The implementation of the mating sections conical with an angle of inclination of the generatrix of the cone from 8-20 degrees allows you to smoothly change the degree of deformation and the force of the rotational hood.

The manufacture of the compensator section by a rotary hood increases its geometric accuracy, and also reduces the amount of machining.

Based on the foregoing, we can conclude that the proposed invention has a "novelty" and "inventive step".

The invention is illustrated by drawings, where in FIG. 1 shows a thick-walled hollow billet with an inner diameter D and wall thickness t; in FIG. 2 shows a semi-finished product obtained after a preliminary operation of rotary drawing with an inner diameter D and a wall thickness of (0.5-0.8) t; in FIG. 3 shows a thin-walled cylindrical shell after the final operation of rotational drawing with an inner diameter D, wall thickness t ending with a conical section of conjugation with an angle of inclination of the generatrix α ° and a compensator conjugated with a conical section with an angle of inclination of the generatrix with a thick-walled section.

The proposed method is implemented as follows. A thick-walled hollow billet is made (as in FIG. 1). The thick-walled hollow billet is subjected to a preliminary operation of rotational drawing and a semi-finished product is obtained, as in FIG. 2. The semi-finished product is degreased and thermally treated to relieve stress. The heat-treated semi-finished product is subjected to the final operation of rotational drawing and a thin-walled shell (as in Fig. 3) is obtained with a wall thickness t ending in a tapered mating section with an inclination angle α of the generatrix. To exclude a sharp increase in the degree of deformation and the effort of rotational drawing, a small compensator with a thickness of the semifinished product is left behind the conical section of the product, the gap between the mandrel and the deforming rollers is increased, and the compensator is rotated to the final dimensions, which ends with the conical section of the interface with the thick-walled section of the shell. To ensure the geometric accuracy specified by the design documentation, it is preferable to process the compensator in two passes, the first of which serves to set a given volume of the compensator.

An example of the use of the invention in the manufacture of a thin-walled shell (as in FIG. 3) by rotational hood from ChS4VI steel with geometric dimensions:

- inner diameter of the shell - ⌀70.2 mm;

- the thickness of the thin-walled cylindrical section - t = 0.48 ± 0.05 mm;

- the thickness of the cylindrical section of the compensator - k = 0.65 ± 0.05 mm;

- compensator length 20 mm.

A thick-walled hollow billet is made from sheet metal with a thickness of 3.5 mm for several cold stamping operations and intermediate heat treatment operations (as in Fig. 1).

The manufacture of a thin-walled shell with a wall thickness of t = 0.48 mm is possible in two operations. The degree of deformation at the preliminary operation is ε = 0.68, at the final ε = 0.57.

The fabricated thick-walled billet is mounted on the mandrel of a rolling machine and a preliminary operation of rotational drawing along the entire length is performed to reduce the roughness of the inner diameter. A semi-finished product is obtained (as in FIG. 2) with an inner diameter of 70.2 mm and a thickness of 1.1 mm. To reduce the roughness of the inner diameter of the end portion of the semi-finished product adjacent to the open end, it is deformed to a wall thickness of (2.8 ... 3) mm.

The resulting semi-finished product is degreased and thermally treated to relieve stress. The heat-treated semi-finished product is subjected to the final operation of rotational drawing and a thin-walled shell (as in Fig. 3) with an inner diameter of ⌀70.2 mm, a thickness of a thin-walled cylindrical section t = 0.48 mm and a thickness of the cylindrical section of the compensator k = 0.65 mm is obtained.

The operation is carried out sequentially, first a thin-walled cylindrical section is deformed, which is completed by forming a conical section of the interface with an inclination angle α = 10 ° on the outer surface, while a cylindrical section with a wall thickness of 1.1 mm (after the preliminary operation) is left with the length (1 ... 9) mm, the rollers are bred to the gap between the mandrel and the rollers of 1.2 mm and the first pass of the rotary hood of the compensator is made to a length of 9 mm to set its volume, a carriage with deforming roles they are returned to the end of the thin-walled cylindrical section, the gap between the mandrel and the rollers is reduced to 0.65 mm, and a second pass of the rotary hood of the compensator for a given length of 20 mm is made. The compensator section is completed by the formation on the outer surface of the conical section of the coupling of the compensator with the thick-walled section of the shell with an angle of inclination of the generatrix α = 10 °. After a rotational hood, the shell is degreased, subjected to final heat treatment - aging and cutting cutting of the seating surfaces.

Claims (2)

1. A method of manufacturing a thin-walled shell, including the manufacture of a thick-walled hollow billet, rotational drawing of a thick-walled hollow billet in two operations, while in the preliminary operation, the hollow billet is deformed along the entire length to obtain a semi-finished product with a thick-walled end section adjacent to the open end, and in the final operation rotary hoods receive a thin-walled shell with an end thick-walled section and a tapered mating section and a compensator section, characterized in that the compensator current is formed in the form of a cylindrical section adjacent to the conical section of the interface conjugated to the thick-walled section of the shell by the conical section of coupling, while the coupling sections are conical with an angle of inclination of the generatrix of 8-20 degrees, heat treatment is performed to relieve stresses between the preliminary and final operations of rotary drawing and final processing of the shell. 2. The method according to p. 1, characterized in that when the rotation hood with a degree of deformation close to the limit, the compensator section is performed in two passes, the first to set the volume of the compensator, and the second to the specified dimensions.

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