SU1237400A1 - Finishing method - Google Patents

Description

The invention relates to abrasive machining and can be used for one- and two-sided finishing with a free abrasive of machine parts and devices on the finishing machines.

The purpose of the invention is to improve the quality of processing, based on the signals of the normal and tangential components of the resultant refinement force measured for each cycle of the workpiece being machined, comparing these signals with predetermined threshold values and introducing additional power to the process.

I

FIG. 1 is presented for the case of one-sided finishing; closed power circuit; finishing machine - tool - abrasive interlayer - workpieces - sample; - finishing machine, and additional disturbing force applied, where M is the reduced mass of the finishing machine and tool from the tool; TO

(

C, - respectively given

stiffness and damping coefficients for the power circuit section finishing machine - tool - abrasive interlayer - workpiece; M - the reduced mass of the processed billets - devices; K, Cj - respectively, the reduced damping stiffness coefficients for the power circuit section of the fixture - finishing machine; m is the reduced mass of the finishing machine from the side of the device.

V

FIG. 2 shows the AFCh of the closed power circuit; the finishing machine; the tool — the abrasive layer — the workpiece being processed — the fixture of the finishing machine, in the complex plane; 1 - the first loop of the AFChH structure of the finishing machine соответствующ corresponding to the frequency of co, 2 - the loop of the AFCh, caused by the action of an additional disturbing force effect, suppressing the disturbance in the chain with frequency co, 3 - the characteristic of the dynamics of the abrasive wear process.

With mechanical finishing with a free abrasive precision surfaces

the effect by which the reaction of the technological system is manifested. in the form of feedback from the start of failure in time.

The nature of the influence of regenerative feedback on the quality of processing depends on both the dynamic characteristics of the abrasive wear process and the elastic structure of the machine O and can lead to instability of the power mode in this system and, consequently, to a decrease in productivity and quality of processing.

Main cause of instability

- 5 (instabilities J of the specified technological system under regenerative excitation is the difference in abrasive wear at the beginning of the introduction of abrasive grains into the material and their repulsion. The action of the deformed material layers, increased hardness with further dispersion. Under these conditions, the technological system is stable only in that case if there is no intersection of the polar diagrams of the right and left sides of its characteristic equation, which determine the dynamics of the abrasive process, respectively 30 of the sewed and the dynamics of the elastic structure of the machine (Fig. 2).

The desire to ensure the sustainability of the process system and to stabilize the quality of processing by increasing the statistical rigidity of the machine is considered unsatisfactory, as this is necessary for this statistical rigidity

25

ka is 4

kgf kmk

for every millimeter

45

40 width of a trace of preparation on a tool. Such a high rigidity of machine tools is impossible.

Therefore, of great practical interest is the use of the method by which it is based. The predetermined dynamic characteristics of the abrasive wear process and the elastic structure of the machine may deform the polar diagrams of the complex frequency characteristics of the abrasive wear process and the elastic structure of the machine so as to prevent them from intersecting. For this, in accordance with 50

details, the quality of processing is determined with the invention, the technological nature of the operating system additionally includes an abrasive wear-active process, through which shivan - a regenerative machine - to the elastic structure of the machine, for example.

374002

the effect by which the reaction of the technological system is manifested. in the form of feedback from the start of failure in time.

The nature of the influence of regenerative feedback on the quality of processing depends on both the dynamic characteristics of the abrasive wear process and the elastic structure of the machine O and can lead to instability of the power mode in this system and, consequently, to a decrease in productivity and quality of processing.

Main cause of instability

 5 (instabilities J of the indicated technological system under regenerative excitation is the difference in abrasive wear at the beginning of the introduction of abrasive grains into the material and their repulsion. The action of the deformed material layers, increased hardness with further dispersion. In these conditions, the technological system under consideration is stable only if if there is no intersection of the polar diagrams of the right and left sides of its characteristic equation, which determine the process dynamics, respectively, abrasively due on 30 nashivani and dynamics of elastic structure of the machine (sig. 2).

The desire to ensure the sustainability of the process system and to stabilize the quality of processing by increasing the statistical rigidity of the machine is considered unsatisfactory, as this is necessary for this statistical rigidity

25

ka is 4

kgf kmk

for every millimeter

Irina billet trail pokstrumentu. That high rigidity of the machine tools is impossible.

Therefore, of great practical interest is the use of the method by which it is based. The predetermined dynamic characteristics of the abrasive wear process and the elastic structure of the machine may deform the polar diagrams of the complex frequency characteristics of the abrasive wear process and the elastic structure of the machine so as to prevent them from intersecting. To do this in accordance

from the tool side in the normal direction, an additional compensating force F (j,

The magnitude and nature of the change in time of this force Rf is determined by the measured signals of the normal and tangential component of the resultant strength of the refinement and taking into account the threshold values limiting the deviations of the indicated components of the resultant force from their average values determining the processing quality parameters.

FQAUu) sin (cot + 4i),

where A is a constant dimensionless coefficient; and, WITH - amplitude and

frequency;

C - phase shift additional disturbing force.

It was established experimentally that the phase shift within (135-180 °) provides the best conditions for suppressing, disturbing effects caused by the wear of the working surface of the tool and changes in the magnitudes of the resultant finishing power at frequency to. At the same time, to improve the accuracy of the macro-relief, the parameters of an additional force disturbing effect signal I of the normal component of the resultant strength of the fine-tuning is formed, and in order to reduce the degree of surface roughness, the parameters of the additional force The disturbing effect is formed by the signal of the tangential composition. The resulting resultant force is refined.

The magnitude of the dimensionless coefficient A is determined by the ratio of the maximum negative real part of the first resonant loop of the complex frequency response of the elastic structure of the machine to the value of H — the overlap of the plots of the complex frequency response of the abrasive wear process and the elastic structure of the machine.

During processing, the selection of the signal of the measured component of the resultant strength of the refinement for the formation of an additional force disturbing effect is made on the basis of the analysis of the following relationships,

1 ° ° J

g - 1- O

If a

then a signal of additional disturbing force action is formed

and.

Ft

- tangential 10

If a

1.0

15

20

five

0

then the signal of additional perturbing force action is formed on the basis of the signal U of the normal component; U, J ° are respectively the reference threshold voltages for the signals of the normal and tangential components of the resultant finishing power {determined by the specified parameters of the processing quality — shape accuracy, degree of surface roughness, and are set for a particular finishing, machine and conditions. refinement experimentally).

Example. One-sided finishing of parts from U8A HRC 53-57 steel was carried out on a modernized machine type S-15 with 5% ACM5 diamond paste on cast-iron grinding, ra

The barrel pressure 0, product rotation frequency rpm, tool rotation frequency 60 rpm, Pro-5 was continuously processed for 9 hours. In the initial processing period, deviations from the tool working surface plane were 1-3 microns. The workpieces had a diameter of 40 mm, a height of 10 mm, an initial deviation from the plane of 0.3 µm, 040 µm, and the diamond paste was updated after 6 minutes of continuous work, based on the loss of performance of the diamond grains after 6-7 minutes of working with one prediction. Working fluid kerosene.

The results of processing are given in table. t and 2 ..,

The application of the invention makes it possible to virtually eliminate the forced editing of a tool, to increase the yield of usable parts after processing by 18-22% in terms of the quality of the treated surface. Under the same processing conditions, the dependence of the machinability on the magnitude of the phase shift was obtained.

0

five

0

Table 1

Editor V. Kovtun

Compiled by A. Semenov

Tehred O.Gortvay Proofreader S. Cherni

Order 3235/16 Circulation 740 Subscription

VNIIPI USSR State Committee

on drlam inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Production and printing company, Uzhgorod, st. Project, 4

Claims (1)

METHOD OF FINISHING parts in cartridges (fixtures) on machines for one-sided and two-sided processing, in which a working load and additional compensating force are applied normally to the working surface of the tool, characterized in that, in order to improve the quality of processing, the complex frequency characteristics of the finishing process are preliminarily determined and the elastic structure of the machine, the processing time t for each cycle of the relative movement of the workpiece on the tool measure the normal and tangential vlyayuschie resultant force finishing and additional compensating force F "is determined from the condition ³ F. = AUutein (c <rt + (f), where A - dimensionless coefficient determined by the ratio of the magnitude of maximal negative real part of the first resonant loop frequency response of the elastic machine structure to the overlap of the diagrams of the complex frequency characteristics of the finishing process and the elastic system of the machine; U and соответственно, respectively, the amplitudes and frequencies of the additional force, which are taken equal to the tang Hoc component with and equal to the corresponding values at which the normal component of Up- and U _Fn - amplitude respectively tangential and normal-governing the composition _of sipy; Upj. and U _Fn — their reference values determined experimentally, based on ensuring the required quality of the machined, 1237400 ki; Cf - phase shift equal to 135-180 °. I 237400 Ί