RU2805022C2 - Method for turning a low-rigid long-length axisymmetric workpiece - Google Patents

Abstract

FIELD: metalworking.

SUBSTANCE: invention can be used for turning a low-rigid lengthy axisymmetric workpiece such as a shaft. The workpiece is based along the outer diameter in self-centring steady rests installed along its length, whereas the axial displacements of the workpiece are fixed by the front spherical centre and the rear corrugated centre. When the workpiece is rotated during one revolution, the curvature of its axis is measured, the plane of maximum deformations is determined taking into account the angle of rotation along the length, and the part is rotated by the plane with the maximum convexity until it coincides with the plane of the cutting tool, while switching the self- centring steady rests to the mode of rigid supports. The value of the planing force is calculated as a function of the measured value of deformation along the length of the workpiece, and a cutter is used with a working profile made along a radius, the value of which is less than the radius of the workpiece being machined by half the cutting depth, and a metal removal width equal to 30°. The final geometric shape of the part is formed by a through cutter on the same lathe with calculated cutting conditions.

EFFECT: use of the invention improves the accuracy of processing.

1 cl, 3 dwg

Description

The invention relates to the field of metalworking of long, axisymmetric, low-rigid shaft-type parts and can be used on universal machines in machining shops of machine-building enterprises.

There is a known method for processing non-rigid parts, which involves processing in self-centering supports with measuring the elastic reaction of the part in the supports, and the feed control is carried out as a function of stabilizing the difference between the cutting forces and the reactions measured in the supports [1].

The disadvantage of this method is the complexity of implementing adaptive control in terms of speed; creation of uneven internal stresses in the volume of the workpiece when it is clamped due to deformation of the workpiece in the transverse direction.

There is a known method for processing workpieces, which involves installing them with axial fixation in ball bearings and supporting them with self-centering steady rests operating in the modes of rigid and damping supports, which operate as a function of the amplitudes of the relative vibrations of the workpiece, switched as the cutter passes [2].

The disadvantage of this method is the lack of control of elastic movements of the workpiece axis and control of cutting modes as a function of its elastic movements, as well as the creation of internal uneven internal stresses in the volume of the workpiece.

The task to be solved by the claimed invention is to increase the accuracy of processing while maintaining it after processing, achieving the following technical results: increasing the stability of the geometry of the part over time due to the formation of a more uniform pattern of stress distribution in the volume of the workpiece; increasing the accuracy of the part in the longitudinal direction through the use of steady rests.

This problem is solved by the fact that in the method of processing a low-rigid long axisymmetric workpiece, the parts are fixed between the front and rear centers from axial movements. The workpiece is based on the outer diameter in self-centering steady rests. The curvature of its axis is determined by rotating the workpiece one revolution. The value of the initial deformation along the length of the workpiece is determined by measuring the movements of the rods of the intermediate self-centering steady rests. Intermediate steady rests operate in damping mode. The plane of maximum deformation is determined and the workpiece is rotated until the plane with the maximum convexity aligns with the plane of placement of the cutting tool. The intermediate self-centering steady rests are switched to the rigid support mode, ensuring the straightness of the workpiece axis. The amount of planing force is set as a function of the measured amount of deformation along the length of the part. The cutting modes are automatically varied so that the values of the axis deflections along the length of the workpiece during cutting are equal to the values of the measured deflections along the length of the workpiece. For processing, a cutting tool is used in the form of a cutter with a working profile made along a radius. The radius value is less than the radius of the workpiece being processed by half the cutting depth. The metal removal width is 30°. Automatically vary cutting modes so that the amount of deflection of the axis of the part in the processing area during cutting is equal to the amount of deflection of the profile of its initial value, taking into account the variable value of its axis along the length. The final geometric shape of the part is formed using a cutter on the same lathe. The part is based on the outer surface, combining the design and technological base, which increases the processing accuracy.

Axial fixation of a part without axial force closure does not create a bending moment.

Measuring the deflection of a part before processing during single-sided rotation makes it possible to determine the numerical value of the deformation of its axis, taking into account the sign and angle of rotation along sections along the entire length.

Simultaneous damping in its sections between self-centering steady rests increases the measurement accuracy by reducing the intensity of vibrations of the part.

Removing metal in convex areas by planing makes it possible to solve the problem of uniform distribution of residual stresses that arise when fixing the workpiece and to stabilize the axis of the part during operation.

The use of self-centering steady rests allows you to stabilize the workpiece axis during the cutting process, because Self-centering steady rests are additional supports.

The use of an automatic control system increases the accuracy and productivity of processing.

The present invention is illustrated by drawings, which show: FIG. 1 - shows a functional diagram of the operation of the installation implementing the method; in fig. 2 - shows section A-A of Fig. 1; in fig. 3 - shows the form of deformation of the axis of the part before and after processing.

The method of turning a low-rigid long axisymmetric workpiece on a lathe is carried out as follows. The workpiece part 1 is installed (Fig. 1) in self-centering rests (SCL) 2, which, depending on the pressure of the working medium in the drive 3 (Fig. 2) of the clamp, can operate in two modes: damper or rigid supports. Intermediate SCL 2, as supports, work in damper mode and as rigid ones. The two outermost SCL 2 act as rigid supports 4. When the SCL operates, the movement of the piston rod 4 is controlled by linear displacement sensors 5. The piston rod is rigidly connected to the central lever of the SCL, which at one end is in contact with the part (Fig. 2). A system of sensors 5 installed on the housing of the SCL 2, relative to the ends of the piston rods 4, measures their movement, which corresponds to the values of the initial deformation of part 1. Part 1, rigidly fixed in the outermost SCL, is rotated one revolution by the drive 6 (fil. 1). Information about the angles of rotation of the part 1 is controlled by the rotation sensor 7, which, together with information from the sensors 5, is supplied to the inputs of the control unit 8, where, based on the measured numerical values of the values of the initial deformation of the axis of the part from Y1 to Y1n, the axis curvature profile is constructed (Fig. 3) and calculated cutting force according to a known formula, taking into account the magnitude of deformation along the axis of the part, varying the cutting speed and thickness of metal removal. When an allowance is removed, moments of unbalanced internal forces arise that tend to deform the part. When planing, the processed surface of a low-rigid part becomes concave and if its profile in shape and deformation values is equal to the original profile from Y2 to Y2n, in this case Y1 is equal to Y2 and Y1n is equal to Y2n, the axis of the part will be straight (Fig. 3). The curvature of its axis is determined by rotating the workpiece one revolution. Next, the magnitude of the initial deformation along the length of the workpiece 1 is determined by measuring the movements of the rods 4 of the intermediate self-centering steady rests. The planing tool 9 has a working cutter profile made along a radius, the value of which is less than the radius of the workpiece by half the cutting depth, and the metal removal width is 30°. The cutter 9 is equipped with a force sensor 10 and is mounted on a transverse support 11. The transverse support has two independent feed drives 12 and 13 in the transverse and longitudinal directions, the outputs of which are connected to the control unit 10. The cutting process is carried out automatically, varying the cutting modes so that the deflection values The axes along the length of the part during cutting were equal to the values of the measured deflections during their control, taking into account their variable axes along the length. The final geometric shape of the part is formed using a cutter on the same lathe with calculated cutting conditions for turning operations.

Information sources

1. A.s. 1294482. USSR MKI V23V 1/00. Method of mechanical processing of non-rigid parts / O.I. Drachev, G.G. Palagnyuk, V.K. Mazur (USSR). - No. 3840927/25-08, application. 10.01.85; publ. 07.030.87, Bull. No. 5. - 5 s. 21. A.s.

2. A.s. 1220731 USSR MKI V23Q15/00. Method for automatic control of processing processes of non-rigid parts / D.A. Rastorguev, O.I. Drachev, A.V. Bobrovsky (USSR). - No. 3743143/25-08, application. 05/23/1984; publ. 03/30/1986, Bulletin. No. - 3s.

Claims (1)

A method for turning a low-rigid long axisymmetric workpiece of a part, including installing the workpiece between the front spherical center and the rear grooved center with fixation of its axial movements, basing the workpiece along the outer diameter in self-centering steady rests located along its length, while the two outer self-centering steady rests are designed to operate in the mode of rigid supports during the entire processing, and the intermediate rests are configured to operate either in the damping mode or in the mode of rigid supports, and processing with specified modes is carried out using a cutting tool, characterized in that after the mentioned basing of the workpiece, the curvature of its axis is determined by rotating the workpiece one revolution and determining the magnitude of the initial deformation along the length of the workpiece by measuring the movements of the rods of intermediate self-centering steady rests operating in the damping mode, the plane of maximum deformations is determined and the workpiece is rotated until the plane with the maximum convexity aligns with the plane of placement of the cutting tool, while intermediate self-centering steady rests are switched to the mode of rigid supports, ensuring the straightness of the workpiece axis, and the magnitude of the planing force is set as a function of the measured amount of deformation along the length of the part, and the cutting modes are automatically varied so that the values of axis deflections along the length of the workpiece during cutting are equal to the values of the measured deflections along length of the workpiece, while for processing they use a cutting tool in the form of a cutter with a working profile made along a radius, the value of which is less than the radius of the workpiece being processed by half the cutting depth, and the metal removal width is 30°, the final geometric shape of the part is formed with a through cutter on the same lathe with calculated cutting conditions for turning operations.