SU1808500A1 - Method for machining holes - Google Patents

Description

The invention relates to metal processing with the removal of shavings and can be used when boring deep holes,

The purpose of the invention is to improve the accuracy and productivity of processing by reducing the level of vibration.

Thus, the essential differences of the proposed method of processing holes are as follows:

control of changes in the vibration damper settings when changing the parameters of the elastic system, for example, the radial stiffness of the tool, when the guides come into contact with the processed surface;

an abrupt increase in the pressure drop of the working agent by the value at which the frictional forces between the loads of the multi-mass vibration damper exceed their inertial forces; at the same time, the vibration damper setting changes - it becomes almost single-mass;

determining the increase in pressure drop from the above ratio.

Figure 1 shows a device for boring holes, General view; figure 2 is a section a-a in figure 1; in Fig.Z the moment of cutting the tool into the hole to be machined; Fig. 4 shows the dependence of the pressure drop of the working agent in the working cavity of the vibration damper on the axial position of the tool relative to the holes being machined, for example, the piston.

The method of processing holes is carried out using a device for boring holes, which contains a cantilever tool 1, made in the form of a boring bar and mounted with a flange part on the spindle of the finishing boring head 2.

The cantilever tool 1 contains a housing 3, a cutting element 4 and two guide elements 5, a support rod 6, a multi-mass vibration damper consisting of a set of weights 7 compressed along the tool axis by a spring 8.

The finishing boring head 2 contains a manifold 9, by means of which a working agent (cutting fluid) is fed through the inner cavity of the spindle and a hole 10 in the body 3 of the tool 1 into the working cavity 11 of the multi-mass vibration damper 7 and then through the holes 12 of the body 3 into the processing zone ...

The tops 13 of the guide elements 5 are displaced in the axial direction relative to the top 14 of the cutting element 5 by the value m = 0.2 ... 1.0 mm. exceeding the value of the working feed per tool revolution. This allows, in front of the apex of the cutting element 5, to form the machined holes 15 and 16 in the workpiece 17 of the piston type.

The hole processing method is carried out as follows.

Before the start of processing, when the tool moves in the idle section 1хх1, a working agent (coolant) is fed into the working cavity 11 of the multi-mass vibration damper 7 under pressure at the Pi inlet and Pr at the outlet, which creates a pressure drop ΔP _in = Pi - Pr. The pressure drop ΔP _{in is} adjusted in such a way as to ensure the optimal operation of the multi-mass vibration damper at the time of the tool penetration in the section 1 _bp , when the guides 5 have not yet come into contact with the machined surface of the hole. It was established experimentally that the optimum value of _Ap is in the range of 1-2 atm.

With an increase in the radial rigidity of the tool, associated with the occurrence of contact of the guides with the workpiece surface (section / 1o1 ~ 4vr /). it becomes necessary to change the vibration damper setting in order to ensure its optimal value. To do this, abruptly (for example, with the help of a water hammer) increases the pressure drop of the working agent in the cavity of the vibration damper by; at which the forces of friction between the loads of the multi-mass vibration damper exceed their inertial forces, i.e. providing the values of the difference ΔΡ ₀ according to the above formula. When the value of the differential pressure Δρ _ο in the working cavity of the vibration damper, it changes from a multi-mass one to a single-mass one (with an increased pressure difference, the vibration damper can be completely turned off, i.e. not move relative to the tool body). Thus, the vibration damper setting changes when the cantilever tool's radial stiffness parameter changes. It has been experimentally established that the optimal value of ΔΡ = ΔΡ ₀ - ΔР _in is in the range of 1-5 atm. ·

After finishing the processing of the hole 15 in sections 1 _XX 2 and 1 _{BP, the} pressure drop in the working cavity of the vibration damper is set ΔΡ _β . When processing the holes 16 in portion (1O2 ~ _Bp 1) pressure drop po1808500 Witzlaus ₀ to the value of LR. This allows, as noted above, to ensure a decrease in the level of vibration during processing.

The technical advantages of the proposed method in comparison with the prototype are:

control of changes in the vibration damper setting when changing the parameters of the elastic system (for example, the radial stiffness of the tool) when the guides come into contact with the machined hole surface:

maintaining the optimal level of the vibration damper setting when changing the parameters of the elastic system using a jump-like change in the pressure drop of the working agent in the vibration damper cavity by an amount that can be obtained from the above ratio:

reducing the level of vibrations during machining due to maintaining the optimal level of vibration damper settings when changing the parameters of tool stiffness:

the ability to process deep interrupted holes without the use of jig bushings.

The socially beneficial benefits derived from the technical are:

increasing the accuracy and productivity of processing by reducing the level of vibrations;

expansion of technological capabilities (it becomes possible to process deep intermittent holes).

Claims (1)

Claim 5 * A method of processing holes, in which an axial movement is imparted to a cantilever tool with cutting and guiding elements, and the vibration damping of the tool is carried out using a multi-mass vibration damper, a working agent is fed into the working cavity and the cutting zone, while a differential is created in the said working cavity pressure, which is characterized by the fact that, in order to increase the accuracy and productivity of processing by reducing the level of vibrations, at the moment of contact of the guide elements with the treated surface, the pressure drop of the working agent is abruptly increased by the value determined by the following relationship, Dr> YG1 (9 Amane U Fnp - S μ where m is the mass of the vibration damper: w is the vibration frequency: Amane - the maximum amplitude of the radial displacement of the vibration damper weights; μ - coefficient of friction between loads; ... Fnp - spring force; S is the transverse area of the load. Φνι. £ Sosgavigel T. Dzhuguryan