RU2466816C2 - Method of forming stack of seamless thin-wall bulky equidistant ogival-shape shells from taper billets - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: outer and inner shells are produced by rotary extrusion at one set of holders the smaller diameter of which is defined by outer shell size, while final ogival section is produced by explosive stamping in one female die. Note here that, first, outer shell tapered billet is subjected to explosive stamping to make outer shell while inner shell is made by explosion to formed outer shell.

EFFECT: lower costs of tooling, better abutment.

1 dwg, 1 ex

Description

The invention relates to the field of metal forming and can be used in the manufacture of a nozzle of a combustion chamber of a liquid rocket engine (hereinafter referred to as LRE).

Obtaining a package of equidistant shells of a lively form is the main problem in the manufacture of nozzle blocks of rocket engines.

All known methods of manufacturing a package of large-sized animated shells (stamping on presses, heat setting, stamping by explosion, rotational extrusion, etc.) are labor-consuming, energy-intensive, and require significant costs for tooling and equipment.

The closest analogue is the method of forming a package of parts of a lively shape, including rotational extrusion of conical blanks of the outer and inner shells from flat blanks, obtaining a package of shells of the final lively shape from a pack of conical blanks by stamping by explosion in one matrix (RU 2317171 C2, B21D 26/08, 20.02 .2008).

The disadvantage of this method is the significant cost and complexity in the manufacture of equipment, and most importantly - the shell has deviations from a given profile, each of its own set of equipment.

A method for forming a package of seamless thin-walled large-sized equidistant shells of an animated shape from conical blanks is proposed. This degree of deformation of up to 5% is typical for nozzle blocks of the upper stages of missiles. The limitation of the degree of deformation is associated with the construction of the inner shell, on the surface of which grooves are milled and the thinning of which has corresponding limitations.

Rolling the cone shell has several advantages:

- it is much easier to make a frame of high accuracy;

- rolling of the conical shell from a flat billet occurs stably - with less thickness difference.

The technical task of the proposed method is the implementation of the shaping of the outer and inner shells by rotational extrusion on one set of frames and stamping by explosion in one matrix, halving the cost of equipment, improving the quality of the fit of the mating surfaces of the package of shells.

This problem is solved using the method of forming a package of seamless thin-walled large-sized equidistant shells of a lively shape from conical blanks. The conical blanks of the outer and inner shells are obtained by rotational extrusion on one set of frames, the small diameter of each of which is set based on the size of the small diameter of the outer shell. From the package of conical blanks by stamping by explosion in one matrix, a package of shells of the final animated shape is obtained. First, from the conical blank of the outer shell, the outer shell is formed by explosion, and the inner shell is formed by explosion along the molded outer shell (see drawing).

The method is illustrated in the drawing. The figure shows the technological scheme of the method.

The method is as follows.

From two flat sheet blanks by the method of rotational extrusion for two transitions, conical blanks of the outer and inner shells are obtained on one set of frames with an angle α. The angle α depends on the design parameters of the shells (Fig. A and b). The design of the outer shell of the package provides for welding the ring with a small diameter of the shell, so the small diameter of the frame is set based on the structural dimensions of the outer shell. Between the transitions of the rotary hood, annealing and etching are performed to relieve the stresses of the workpiece metal. Obtaining a package of shells of the final animated form from a package of conical blanks of the outer and inner shells is most efficiently performed by explosion stamping. Before the shells are formed, a vacuum is created between the die and the workpiece. A package of shells of the final animated shape is obtained from a package of conical blanks by stamping by explosion in one matrix (Figs. C and d). First, from the conical blank of the outer shell, the outer shell is formed by explosion. The inner shell is formed by explosion on a molded outer shell. The resulting package of shells is removed from the matrix, followed by calibration of the package, if necessary.

An example implementation of the method.

For the manufacture of the outer shell, a flat sheet billet of steel grade 12X21H5T, with a diameter of 1200 mm, and a thickness of 2.5 mm is selected.

Set the workpiece on a rotary extrusion machine. First, perform the 1st transition of rotational extrusion and get a conical blank of the shell with a thickness of 1.4 mm Between the transitions, thermal annealing and etching are performed to relieve the stresses of the workpiece metal. Then perform the 2nd transition of the rotary hood and get a conical outer shell with a thickness of 0.6 + 0.12 mm Repeat annealing and etching.

For the manufacture of the inner shell using a frame for rolling the outer shell. On a rolling mill, a flat sheet of steel 12Kh18N10TSh 12 mm thick is installed. Then a rotational extrusion is carried out by a deforming roller in two transitions with intermediate annealing and etching. The result is a conical billet with a thickness of 4.7 + 0.18 mm

Further shaping of the package of equidistant animated membranes is obtained alternately in one matrix - by stamping by explosion.

The conical blank of the outer shell is placed in the matrix for explosion and the profile is formed along the “belts” in order to avoid sliding of the shell. Prior to molding, both the outer shell and the inner create a vacuum between the die and the workpiece.

Then cut technological allowances at the molded outer shell and re-install it in the matrix. The inner shell is placed in the matrix and formed by its explosion along the molded outer shell. The resulting package of shells is removed from the matrix. Control the profile and clearance in the package.

As a result of this shaping, a package of equidistant shells of a lively shape with an optimal soldering gap is obtained.

Claims (1)

The method of forming a package of seamless thin-walled large-sized equidistant shells of a lively shape from cone blanks, including rotational extrusion of cone blanks of the outer and inner shells from flat blanks, obtaining a package of shells of the final shape from the pack of conical blanks by stamping by explosion in one matrix, characterized in that the conical blanks the inner shells are obtained by rotational extrusion on one set of frames, the small diameter of each of which is set based on the size of the small diameter of the outer shell, and upon receipt of the package of shells of the final animated shape from the package of conical blanks by stamping by explosion in one matrix, first the outer shell is formed by explosion from the conical blank of the outer shell, and the inner shell is formed by explosion along the molded outer shell.