RU2351425C2 - Method of production of thin-walled heavy shell - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to metal deformation process. Particularly it relates to method of producing of thin-walled heavy shell of ogival form with reduced inclination of generatrix from minor diameter to major. Method is implemented by means of holder at lengthwise movement no less than two spinning tool, installed with clearance relative to holder with ability of its correction during the process of treatment by means of rotary drawing from plate stock per three passage. The first passage is implemented without change of blank thickness. Following passage of rotary drawing is implemented with calculated deformation ratio on generatrix length till the critical point, specified by inclination value of generatrix and relation between diameter and shell-wall thickness in particular point. Following passage - with minimal deformation ratio. Final passage is implemented with calculated deformation ratio till critical point and with maximal deformation ratio after it.

EFFECT: accuracy increasing of geometry, maintainability, constructional durability.

3 cl, 1 dwg, 1 ex

Description

The invention relates to the processing of metals by pressure, in particular to a method for implementing the rotational extrusion process.

There is a method of manufacturing shells of a lively shape by multi-jaw pressing processing of a sheet billet mounted on a rotating frame during longitudinal movement of the pressing tool installed with a gap relative to the latter, and the gap for any point in the profile is adjusted during processing (Patent No. 2255827, IPC B21D 22/16 )

This method is difficult to use to obtain thin-walled large-sized shells of a lively shape with a decreasing small (less than 40 °) angle of inclination of the generatrix from a small diameter to a large and small geometric degree of expansion from a sheet of high alloy steel due to loss of metal stability, starting from a certain (critical) points on the generatrix of the shell.

The technical task is to obtain a thin-walled large-sized shell of a lively shape with a decreasing small value of the generatrix tilt angle, a small geometric degree of expansion, with high accuracy of geometric dimensions, ensuring operational reliability and high structural strength.

This technical task is carried out using a method of manufacturing a thin-walled large-sized shell of a lively shape with a decreasing small angle of inclination of the generatrix in the range from 28 ° C to 8 ° C by multi-jaw pressing from a sheet blank mounted on a rotating frame during longitudinal movement of the pressing tools installed with a gap relative to the latter with the ability to adjust the gap during processing at any point in the profile. During the first transition, a rotational hood is carried out without observing the sine law, i.e. without thinning, then a rotational hood is carried out with a calculated degree of deformation along the generatrix to a critical point, determined by the angle of inclination of the generatrix and the ratio of the diameter and thickness of the shell. After the critical point, the rotational hood is carried out with a minimum degree of deformation. The final transition of the rotational hood is carried out with the estimated degree of deformation along the generatrix to the critical point and the maximum degree of deformation after it. During the rotational drawing of a thin-walled large-sized casing, at least two pressing tools lying in the same plane, arranged uniformly around the circumference, are used, while their peripheral speed remains constant along the entire length of the forming casing. The position of the critical point on the generatrix of a thin-walled large-sized shell characterizes the degree of stability of the workpiece during rotational drawing and the rigidity of the AIDS system. The angle of inclination of the generatrix at the critical point is determined from the ratio of the maximum possible deviation of the gap between the rolling rollers and the frame along the normal and the maximum actual deviation of the gap. The ratio of the diameter to the thickness of the shell at which the corrugation of the workpiece metal does not occur at a critical point. selected experimentally. Those. on the experimental billet, the minimum shell thickness within the tolerance is selected at which corrugation of the metal of the billet under the rollers does not occur during rotational drawing. The resulting ratio of thickness to diameter is used in the manufacture of subsequent after the experimental parts.

The method is illustrated in the drawing.

The drawing shows a diagram of a large shell with a decreasing small angle of inclination of the generatrix α.

Where I is the transition without observing the sine law;

II - transition of the second;

III - the third transition;

S ₀ - the thickness of the workpiece;

S _{1 is the} shell thickness after the 2nd transition to a critical point;

S ₂ is the shell thickness after the 2nd transition after the critical point;

S ₃ - shell thickness after the 3rd transition;

α ₁ - the angle of inclination of the generatrix of the shell with a smaller diameter;

α ₂ - the angle of inclination of the generatrix at a critical point;

α ₃ - the angle of inclination of the generatrix of a larger diameter.

The method is as follows.

A sheet blank in the form of a disk with a thickness of S _{0 is} fixed at the end of a vertically arranged frame, press tools are installed on both sides of the frame with a gap relative to the surface of the latter. Pressing tools are evenly spaced on one level. The critical point is determined by the angle of inclination of the generatrix α ₂ from the ratio of the maximum possible deviation of the gap between the rolling rollers and the frame along the normal and the maximum actual deviation of the gap. From the ratio of diameter to shell thickness, the minimum allowable shell thickness at a critical point is determined.

During the first transition, the rotation hood is carried out without changing the thickness of the workpiece. The next transition of the rotation hood is carried out with the calculated degree of deformation along the length of the forming shell to the critical point and with the minimum degree of deformation after it, obtaining the shell thickness S ₁ and S ₂ . The final transition is carried out with a calculated degree of deformation to a critical point and with a maximum degree of deformation after it, obtaining a shell thickness S ₃ . In the process of rotational drawing with the help of CNC, the gap between the pressing tool and the casing is adjusted in order to obtain a given thickness of the casing during the rotational drawing and equal-thickness casing after final processing.

An example implementation of the method.

A billet of steel 12X18H10T in the form of a disk with a diameter of 1800 mm and a thickness of 12 mm is fixed at the end of the frame.

It is necessary to obtain a thin-walled large-sized shell of a lively shape with a decreasing angle of inclination of the generatrix from 28 ° C to 8 ° C, with a minimum diameter of 500 mm, a maximum diameter of 1500 mm, a height of 1600 mm, and a shell thickness of 3.5 mm. Install two pressure tools with a gap relative to the frame, diametrically opposite.

First, the critical point is determined for the final transition of the rotational hood through determining the angle of inclination of the generatrix of the shell.

The angle of inclination is determined from the ratio of the actual runout of the frame and the maximum possible deviation of the gap. For the second transition, the position of the critical point is determined by transferring the position of the point from the final transition along a line parallel to the axis of rotation of the workpiece.

In the attached example, the angle of inclination of the generatrix at the critical point is determined as follows:

α = arccos (ΔZ / ΔR),

where k is the coefficient of the maximum possible deviation of the gap from the sine law, k = 0.03;

Z is the gap, Z = 3.2 mm;

ΔZ = 0.03 × 3.2 = 0.096;

ΔR - runout of the frame on one side, ΔR = 0.1 mm,

α = arccos (0,096 / 0,1) = arccos 0,96 = 16,26 ° ≈17 °.

The critical point is characterized by the angle of inclination of the generatrix α≈17 °, and S / D × 100 = 0.32.

The first transition is carried out without thinning, the feed speed of the rolling roller is 3 mm / s, the rotation speed of the frame is 0.62-1.5 r / s, the peripheral speed of the roller is 2.35 m / s. At the next transition, the rotation speed of the frame is the same, the feed speed of the rolling rollers is 2 mm / s. A rotational hood is carried out with a calculated degree of deformation along the generatrix to a critical point, after which a rotational hood is carried out with a minimum degree of deformation. The final transition is carried out with a calculated degree of deformation to a critical speed and with a maximum degree of deformation after it. The peripheral speed of the roller is 2.35 m / s.

Thus, the obtained thin-walled large-sized shell of a lively shape with a decreasing small angle of inclination of the generatrix from a small diameter to a large and small geometric degree of expansion was obtained with high accuracy of geometric dimensions, ensuring equal thickness, operational reliability, and high structural strength.

Claims (3)

1. A method of manufacturing a thin-walled large-sized shell of a lively shape with a decreasing angle of inclination of the generatrix, comprising multi-jaw pressing machining of a sheet stock mounted on a rotating frame during longitudinal movement of the pressing tools installed with a gap relative to the latter with the possibility of adjusting the gap, characterized in that the first transition is rotational the hoods are carried out without changing the thickness of the workpiece, the next transition of the rotational hoods is carried out with the calculated st by deformation along the length of the generatrix of the shell to a critical point, determined by the angle of inclination of the generatrix and the ratio of the diameter of the shell to the thickness, the subsequent rotational drawing is carried out with a minimum degree of deformation, the final transition of the rotational drawing is carried out with a calculated degree of deformation to a critical point and with a maximum degree of deformation after it . 2. The method according to claim 1, characterized in that at least two pressing tools are used, arranged uniformly around the circumference in the same plane. 3. The method according to claim 1, characterized in that the peripheral speed of the pressing tool along the entire length of the generatrix is set constant.