RU2341348C2 - Method for manufacture of single-corrugation bellows - Google Patents

Abstract

FIELD: technological processes; metallurgy.

SUBSTANCE: thin-walled tubular billet is manufactured with internal diameter close to internal diameter of bellows cylindrical part. Then several operations of rotational extrusion and thermal treatment are alternated for removal of internal strain with further installation of tubular billet in device for shaping of corrugation. Single-corrugation bellows is shaped from tubular billet on the mandrel with annular groove by means of creation of external pressure in the corrugation area with ends of tubular billet previously pressed to mandrel with the possibility of their sliding between mandrel and clamp.

EFFECT: quality of bellows is increased.

3 cl, 3 dwg, 1 ex

Description

The invention relates to methods for manufacturing bellows and can be used in the manufacture of high-strength bellows mainly from maraging steel for operation at high pressures and temperatures.

A known method of manufacturing corrugated pipes using rotatable with the same frequency and to one side of the screw and cartridge with a variable pitch helix. In this case, the cartridge with deforming rollers is located outside the pipe, and the screw inside the pipe. The pipe has only translational motion - the feed and in the corrugation process must be rolled completely (over the entire length), (see the book "Handbook of cold stamping" Romanovsky VP - Leningrad: Mechanical Engineering. - 1979. C 278).

Disadvantages:

1. In this way it is impossible to produce a single-sided bellows, since the tube billet is fed into the deformation zone by friction forces arising between the working surfaces of the device and the surfaces of the pre-corrugated pipe along the entire length.

2. In the process of rolling corrugations of especially thin-walled pipes, the formation of folds and other defects is inevitable.

A known method of manufacturing a single-bellows bellows, including the manufacture of a thin-walled tubular billet with an inner diameter close to the inner diameter of the bellows in a normal section passing through the top of the corrugation, installation of the tubular billet in the matrix for forming with restriction from radial movement of the ends and the middle of the tubular billet, subsequent radial molding of the corrugation with axial draft of the billet in the matrix by applying internal pressure with the full measured volume of the working fluid supplied to the cavity tube billet, while axial settlement in the matrix is carried out while maintaining internal pressure 3 ... 6% less than the maximum pressure of the working fluid in the internal volume during radial molding (see patent RU 2192325, B21D 15/10, 51/12, 10.11. 02).

Disadvantages:

1. The manufacture of a single-wave bellows in this way occurs with a predominance of tensile stresses in the metal of the bellows, especially in its cylindrical part, which leads to a local reduction of the walls up to ruptures with the subsequent rejection of such bellows;

2. Large material costs, since for the implementation of the method at both ends of the pipe billet, allowances are required for a length of more than two heights of the bellows corrugation, which are removed by cutting after molding the bellows.

3. The loss of stability, with a sharp distortion of the geometric shape of the bellows by internal stresses, after trimming the end allowances complicates further processing and reduces the quality of the bellows.

4. Complex and expensive equipment and technological equipment for implementing the method.

The proposed invention solves the problem: improving the accuracy of manufacturing the bellows corrugation in height and height, reducing material and labor costs associated with its production.

The technical result obtained by carrying out the invention consists in the manufacture of a thin-walled bellows without loss of stability and distortion of the geometric shape after molding the corrugation and cutting the end allowances.

The specified technical result is achieved by the fact that in the method of manufacturing a single-sided bellows by manufacturing a thin-walled tubular billet, including the sequential alternation of several operations of rotational extrusion and heat treatment to relieve internal stresses, followed by installation of the tubular billet in the device for forming a corrugation, and the formation of a single-bore tubular bellows, new is that a thin-walled tubular billet is made with an inner diameter, bl viscous inner diameter of the cylindrical part of the bellows, and the bellows corrugation formation produced on a mandrel with an annular groove which serves for forming and placing of the corrugation, by creating external pressure at zone at the corrugation ends of the pre-pressed tubular blank to the mandrel with the possibility of sliding between the mandrel and the clamp.

For bellows with high corrugation, corrugation is produced in two steps. The external pressure in the corrugation zone first forms corrugations with large radii of mating surfaces, then finally forms corrugations of a given height and geometry.

The bellows corrugation is formed either on a rotating mandrel with locally pressed ends of the tube stock by local external pressure in the corrugation zone created by a deforming roller, the profile of which corresponds to the corrugation profile, or on a stationary detachable mandrel with pressed ends of the tube stock by local external pressure in the corrugation zone with liquid or an elastic medium, wherein the mandrel diameter corresponds to the inner diameter of the bellows, and the groove profile on the mandrel corresponds to the profile of the bellows corrugation.

A method of manufacturing a single-sided bellows is illustrated by drawings, where:

figure 1 shows a thin-walled tubular billet with an inner diameter D, height H and wall thickness t;

figure 2 shows a diagram of the formation of a single-bellows bellows (with a diameter of the cylindrical part D, a height h and a height of the corrugation T), on a rotating mandrel roller. The designations in the diagram mean:

Pos.1 - mandrel;

pos.2 - deforming roller;

Pos. 3 - bellows;

n is the frequency of rotation of the mandrel;

n1 is the rotational speed of the deforming roller;

Q is the clamping force of the ends of the tube stock to the mandrel;

S - radial feed of the deforming roller;

figure 3 shows a diagram of the formation of a single-bellows bellows (with a diameter of the cylindrical part D, height h and height of the corrugation T, wall thickness t) on a stationary detachable mandrel with local external pressure in the corrugation zone created by the liquid. The designations in the diagram mean:

Pos.1 - mandrel;

pos.2 - a device for forming a corrugation;

Pos. 3 - bellows;

Q is the clamping force of the ends of the tube stock to the mandrel;

q is the fluid pressure.

The method is as follows.

Subsequently, a thin-walled shell with an inner diameter D1 <D and a wall thickness t is made of a thick-walled hollow billet in several rotational extrusion operations. After each operation of rotational extrusion, the shells are cut into rings, which are subjected to heat treatment to relieve stresses. After the last heat treatment, a thin-walled billet with an inner diameter D, wall thickness t and height N.

The formation of the bellows corrugation roller is as follows.

On the mandrel installed in the spindle of the lathe with an annular groove for the formation and placement of the bellows corrugation, install the tube stock symmetrically to the annular groove, press the ends of the tube blank to the surface of the mandrel with force Q and rotate the mandrel. The force Q is selected empirically, based on the conditions for the qualitative formation of the corrugation without reducing the thickness and the formation of folds on the corrugation. A deformation roller is brought to the outer surface of the tube billet in the corrugation zone, the profile of which corresponds to the corrugation profile, then a deformation roller is fed to the axis of the mandrel and local deforming pressure is created, which overcomes the frictional force created by the clamp, gradually pulls the metal into the annular groove of the mandrel without folds . After the corrugation is formed, the deforming roller is removed, the rotation of the mandrel is removed, the clamping device is removed from the cylindrical part of the bellows and the bellows is removed from the mandrel.

The formation of the bellows corrugation by a liquid is as follows.

A tube stock with an inner diameter D, wall thickness t and height H is assembled with a detachable mandrel, a mandrel with a tube stock is installed in the device for forming a corrugation, the ends of the tube stock are pressed to the surface of the mandrel by the force “Q”. Liquid is gently supplied to the device for forming the corrugation, creating a local (in the corrugation section) excess pressure "q", which, overcoming the frictional force created by the clamp, gradually draws the metal into the annular groove of the mandrel without folds. After the formation of the corrugation, the fluid supply is stopped. The clamp is removed from the cylindrical parts of the bellows, a detachable mandrel with a bellows is removed from the device for forming a corrugation, the mandrel is disassembled and the bellows is removed.

Considering that the deforming force was applied locally in the corrugation zone, the formed bellows acquires additional rigidity and maintains a geometric shape close to regular, which greatly simplifies further processing.

Example. A thin-walled shell with an inner diameter of D1 mm and a wall thickness of t is made of maraging steel in three or four rotational extrusion operations, and after each operation of rotational extrusion, the shell is cut into rings, which are quenched to relieve internal stresses and stabilize the internal diameter at temperature hardening. After the final heat-stabilizing hardening, a tube billet with an inner diameter D, thickness t and height N.

On the mandrel installed in the spindle of the lathe with an annular groove for forming and placing the corrugation, the tube stock is installed symmetrically to the groove and the ends thereof are pressed to the mandrel by the force Q. If the mandrel is detachable in the middle of the corrugation, then the clamp can be made in the form of a collet clamp. Next, the mandrel with the tube stock is rotated, a deformation roller, previously set symmetrically to the annular groove by the working profile, is fed, the deformation roller is fed in, creating a local deformation pressure, which, overcoming the frictional force created by the pressing force, gradually draws the metal into the annular groove, forming a corrugation with a height T.

After the corrugation is formed, the deforming roller is removed, the rotation of the mandrel is eliminated, the clamping force Q is removed from the cylindrical part of the bellows and the bellows is removed from the mandrel.

Claims (3)

1. A method of manufacturing a single-sided bellows, including the manufacture of thin-walled tubular billets by sequentially alternating several operations of rotational extrusion and heat treatment to relieve internal stresses, the subsequent installation of the tubular billet in the device for forming corrugation and the formation of a single-bore bellows from the tubular blank, characterized in that the thin-walled tubular billet made with an inner diameter close to the inner diameter of the cylindrical part of the bellows, and The bellows corrugation is produced on a mandrel with an annular groove used to form and place the corrugation by creating external pressure in the corrugation zone with the ends of the pipe billet pre-pressed against the mandrel with the possibility of their sliding between the mandrel and the clamp. 2. The method according to claim 1, characterized in that the formation of the bellows corrugation is carried out in two steps, creating external pressure in the corrugation zone previously and finally. 3. The method according to claim 1 or 2, characterized in that the formation of the bellows corrugation is carried out on a rotating mandrel, and the external pressure is created locally at the locally pressed ends of the pipe billet.

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