RU2417854C1 - Method of producing thin-wall shells - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to metal forming and may be used in producing thin-wall shells from maraging steel. Hollow shaped workpiece is made from bar section by extruding and cutting. Shaped workpiece consists of large and small cylinders jointed by adapter cone and features wall thickness varying in height. Large cylinder wall thickness is twice is lathe as that of adapter cone. That workpiece is subjected to extrusion and thermal treatment for stress relief to make thin-wall shell. Rotary extrusion is carried out in three stages with tolerable strain of thin-wall shell. At first stage, workpiece large cylinder is machined to wall thickness equal to or smaller than that of adapter cone. Then local rotary swaging of larger cylinder and final machining are performed.

EFFECT: reduced metal consumption, higher quality of final products.

3 cl, 6 dwg, 1 ex

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 from maraging steel.

A known method of manufacturing long thin-walled shells from maraging steel, comprising cutting the initial billet from a sheet, manufacturing in several cold stamping operations a hollow shaped billet with a constant wall thickness consisting of small and large cylinders mated with a transition cone, while cold stamping operations are accompanied operations of intermediate heat treatment, face trimming, washing, applying and removing grease, etc., rotational extrusion (rotational hood with thinning) bolochki two operations large cylinder with a degree of deformation of 70% and 60% respectively, and the intermediate step between the heat treatment, the local large cylinder rotary compression inside and final processing. The method is adopted as a prototype (see RTM 3-1674-85, pp. 175-190).

The disadvantages of the prototype are:

1. A large number of cold stamping operations and the accompanying operations of interoperational heat treatment to relieve stresses, cutting operations to eliminate open end irregularities, flushing, applying and removing grease, etc. in the manufacture of high hollow shaped billets and, as a result, a significant consumption of auxiliary materials with high labor intensity of work;

2. Large metal consumption in the manufacture of a hollow shaped billet due to sheet waste during cutting of the initial billet, destruction of the billets during multi-operation cold stamping, multiple interoperational trimming of the ends;

3. Low quality hollow shaped workpiece:

- the zone close to the open end has an increased thickness difference, leading to an increase in the ovality of the shell;

- the presence on the surfaces of the hollow shaped billet of metallurgical defects and defects acquired during its manufacture during subsequent rotational extrusion of the shell, especially with a degree of deformation approaching the limit, contributes to the formation of captivity, peeling, scaly on its surfaces;

4. The high cost of sheet metal.

The present invention solves the problem of improving quality and reducing material costs in the manufacture of long thin-walled shells from maraging steel.

The technical result obtained by carrying out the invention is to reduce the consumption of metal, to increase the geometric accuracy and quality of the surfaces of the shell, to reduce the departure of hollow shaped billets in the marriage of destruction.

The specified technical result is achieved by the fact that in the method of manufacturing long thin-walled shells from maraging steel, comprising a segment of the initial billet, the manufacture of a hollow shaped billet consisting of large and small cylinders conjugated by a transition cone, rotational extrusion of a long-sized thin-walled shell for several operations with an intermediate heat treatment to relieve stresses, local rotational compression of the large cylinder inward and final processing, new is the hollow molded workpiece made from a length of extruded bar by cutting and subsequent treatment with a variable wall thickness adjustment, and the rotary squeezing produce three operations with an acceptable degree of deformation, wherein in the first operation, the processing of a large cylinder.

A hollow shaped workpiece is made with a wall thickness of a large cylinder of a greater wall thickness of the transition cone approximately 2 times.

The rotational extrusion of a large cylinder in the first operation is carried out to a wall thickness equal to or less than the wall thickness of the transition cone of the hollow shaped workpiece.

The manufacture of a hollow shaped workpiece by extruding from a section of a bar allows the use of cheaper rolled products — a bar, to shorten the cycle of its manufacture, and to reduce the range of technological equipment.

The use of a hollow shaped billet with a variable wall thickness along its height with the wall thickness of a large cylinder of a larger wall thickness of the transition cone by about 2 times leads to a decrease in its height, and subsequent rotational extrusion of a thin-walled shell in three operations leads to an increase in the volume of plastic processing instead of cutting and as a result, to a decrease in metal consumption.

Processing by cutting a hollow shaped workpiece improves its quality, because allows you to eliminate surface defects formed in previous operations, as well as to increase the geometric accuracy of internal diameters and thickness variations, to reduce ovality.

The manufacture of a thin-walled shell in three operations of rotational extrusion with rotational extrusion in the first operation of a large cylinder to a wall thickness smaller than the wall thickness of the transition cone leads to a decrease in the thickness of the large cylinder, as well as to a decrease in the degree of deformation in the next operation, which favorably affects the geometric accuracy of the thin-walled shell and mechanical properties of metal.

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

The invention is illustrated by drawings, where

- figure 1 shows a hollow shaped billet obtained by hot extrusion, consisting of a large cylinder 1, a small cylinder 2 and a transition cone 3;

- figure 2 - a hollow shaped billet with a variable wall thickness in height, obtained by machining an extruded billet consisting of a large cylinder 1 with an inner diameter “D” and a wall thickness “a ₀ ”, a small cylinder 2 with an inner diameter “d” and wall thickness “b ₀ ” and transition cone 3 with wall thickness “c ₀ ”, with “a ₀ ≈2c ₀ ”;

- figure 3 - the shell after the first operation of rotational extrusion, consisting of a large cylinder 1 with a wall thickness of “a ₁ ”, a small cylinder 2 and a transition cone 3 with a wall thickness of “c ₀ ”, while “a ₁ ≤c ₀ ”;

- figure 4 - the shell after the second operation of rotational extrusion, consisting of a large cylinder 1 with an inner diameter “D” and a wall thickness “a ₂ ”, a small cylinder with an inner diameter “d” and a wall thickness “b ₂ ” and a transition cone 3 with wall thickness “c ₂ ”;

- figure 5 - the shell after the third operation of rotational extrusion, consisting of a large cylinder 1 with an inner diameter “D” and a wall thickness “a”, a small cylinder 2 with an inner diameter “d” with a wall thickness “b” and a transition cone with a thickness walls “c”;

- Fig.6 - the shell after the operation of the local rotational compression of the large cylinder 1 inward and segments of the end allowances.

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

The initial bar is cut into measuring segments with a volume equal to the volume of the extruded shaped billet, the measured segments are heated to the extrusion temperature, the heated segment is set into a stamp, the hollow shaped billet is extruded in the form of large 1 and small 2 cylinders mated with a transition cone 3 with a variable wall thickness according to height (see figure 1), machining the inner and outer surfaces eliminate the defective layer and get a geometrically accurate hollow shaped billet with a variable wall thickness in height with thickness large cylinder 1 greater thickness of the transition cone wall 3 about 2 times (see FIG. 2). Set the hollow shaped workpiece on the mandrel and rotationally extrude the large cylinder 1 of the shell to a wall thickness less than or equal to the wall thickness of the transition cone (see figure 3). The shell is washed and heat treated to relieve stress. A second operation of rotational extrusion of the shell over the entire length is performed (see Fig. 4), the shell is washed and subjected to heat treatment. A third operation of rotational extrusion is performed and a long, thin-walled shell is obtained (see FIG. 5), the shell is mounted on a mandrel for rotational compression, and local compression of the large cylinder inside is performed (see FIG. 6). After crimping, the end allowances are cut, the shell is washed, thermally treated and final processing is performed by cutting the landing surfaces.

An example of manufacturing a long thin-walled shell with a wall thickness of a large cylinder a = 0.5 mm and a total length L = 870 mm

The initial bar with a diameter of 60 mm is cut into measuring segments with a volume equal to the volume of the extruded shaped billet, the measured sections are heated to the extrusion temperature, the heated segment is set into a stamp, the hollow shaped billet is squeezed 105 mm high in the form of large 1 and small 2 cylinders mated with a transition cone 3 (see FIG. 1), cutting the inner and outer surfaces eliminates the defective layer and obtain a geometrically accurate hollow shaped workpiece with a variable wall thickness in height (see FIG. 2) with a diameter a large cylinder D = 70 mm and a wall thickness a ₀ = 7 mm, with a small cylinder diameter d = 45 mm and a wall thickness b ₀ = 3.5 mm and a transition cone 3 with a wall thickness with ₀ = 3.5 mm Install a hollow shaped the workpiece onto the mandrel and rotationally extrude the large cylinder of the shell to a wall thickness a ₁ = 3.1 ÷ 3.5 mm (less _than or equal to the wall thickness of the transition cone of the hollow shaped workpiece) (see figure 3). The shell is washed and heat treated to relieve stress. A second operation of rotational extrusion of the shell to the wall thicknesses of the large cylinder a ₂ = 1.1 mm, the small cylinder b ₂ = 2.2 mm and the transition cone c ₂ = 2 mm is performed (see FIG. 4), the shell is washed and heat treated. The third operation of rotational extrusion is performed and a long-sized thin-walled shell with a wall thickness of a large cylinder a = 0.5 mm, with a wall thickness of a small cylinder b = 0.8 mm and a wall thickness of a transition cone c = 0.8 mm is obtained (see Fig. 5 ), install the shell on the mandrel for rotational compression and carry out local compression of the large cylinder inward. After crimping, end allowances are cut to a size of L = 870 mm (see Fig. 6). Then the shell is washed, thermally treated and final processing is performed by cutting the seating surfaces.

Claims (3)

1. A method of manufacturing thin-walled shells from maraging steel, comprising the manufacture of a hollow shaped billet consisting of a large and a small cylinder mated with a transition cone, rotational extrusion extrusion of a thin-walled shell with an intermediate heat treatment to relieve stresses, local rotational compression of a large cylinder thin-walled shell inward and final processing, characterized in that a hollow shaped workpiece with a variable thickness height by height from a bar segment by extrusion and subsequent machining, and rotational extrusion is carried out in three operations with an acceptable degree of deformation of a thin-walled shell, on the first of which a large cylinder of a hollow shaped billet is processed. 2. The method according to claim 1, characterized in that the hollow shaped billet is made with a wall thickness of a large cylinder exceeding the wall thickness of the transition cone by about 2 times. 3. The method according to claim 1, characterized in that in the first operation of rotational extrusion, the processing of a large cylinder of a hollow shaped billet is carried out to a wall thickness equal to or less than the wall thickness of its transition cone.

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