SU1143514A1 - Method of measuring tangential component of cutting force in multicutter turning - Google Patents

Abstract

A METHOD FOR MEASURING A TANGENTIAL COMPONENT CUTTING FORCE WITH A MULTIPLE POINT, which measures the load on the machine spindle, the radii of machining and feeds per revolution, and with the fact that, in order to increase speed, the electrical conductivities of the contacts of the cutter are a part of a detail, The tangential component of the cutting force on the individual cutters is determined by the expression .., JiiK.U.R 4, -Gb1h and where -the cutting power; Q-spindle speed; ) 5i - respectively, the current radius of processing and the sub-turn on the turn of the -th cutter; Q; - electrical conductivity of the i-th contact; cutter - part; n is the number of simultaneously operating incisors.

Description

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The invention relates to the field of measurement of cutting forces on metal cutting machines and can be used for multi-tool turning with an electrically conductive tool for measuring tangential component cutting forces differentially on each cutter. A known method for measuring cutting forces with double-blade turning involves the direct measurement of the tangential component of the cutting force Pj ,. on one cutter. and the component of the other cutter P is obtained by subtracting the magnitude of the force sensor signal from the magnitude of the signal proportional to the required drive power of the main motion - t J The disadvantage of this method is the need to insert sensitive elements into the support units of the machine, which causes significant structural difficulties, reduces the rigidity of these nodes, and hence the technological capabilities of the machine. The known method of measuring cutting forces during multi-tool turning, by which the load on the machine spindle is measured, alternately changes the feed rate on each of the cutters and, by comparing the increment of load on the spindle, judges the cutting force on individual cutters. The disadvantage of the known method is extremely low speed. at best, a few seconds at best, which, given the high dynamics of the cutting process, leads to very low reliability and practically does not allow the method to be used in automatic systems, Skogen controlling the cutting forces no. The purpose of the invention is to increase the measurement activity. This goal is achieved by the fact that, in the method of measuring the tangential force of the cutting force, neither in the case of multi-blade turning, which involves measuring the load on the machine spindle, the radii of processing and feeds per revolution, is added. measure the electrical conductivities of the cutter-part contacts and determine the tangential component P of the cutting force on the individual cutters by expression. R . l l where W is the cutting power; machining radius of i-th cutterJ feed per revolution of i-th cutter; electrical conductivity of the 1st contact cutter - detail, angular spindle speed; the number of simultaneously operating incisors. The drawing shows a block diagram of a device that implements the proposed method. The device contains a block of AC amplifiers, the inputs of which are connected to the cutters 2, electrically isolated from the mass of the machine, and through the measuring current collector 3 to the workpiece 4, and the outputs to the input of the calculation unit 5. In parallel with the inputs of the block 1 amplifiers are connected the inputs of the block 6 threshold elements. Other inputs of calculating unit 5 are connected to the outputs of unit 7 of sensors for processing radius, unit 8 for feed sensors per revolution, and also for output of sensor 9 for torque (cutting power). The cutters 2 through the resistors 10, and the workpiece 4 through the power current collector 11 are connected to the secondary winding of the step-down transformer 12. The essence of the method is as follows. Experimental studies have established that the correlation between the electrical conductivity of the cutter contact is the part and the tangential component of the cutting force PJ. regardless of the current values of the depth of cut t and wear of the cutter, the coefficient can be represented as the expression P, -CO V - the coefficient for this pair of cutter materials and part; - cutting speed.

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During multi-chisel turning, the total load on the machine spindle is determined by the expression

.v

U

where M is the torque on the spindle.

Taking into account that the cutting speed of the 1st cutter is determined by the expression V; - WV after substituting it into you. Fraction (2) we get:

R.,;. (BUT

After substitution of expression (4) into expression (3), we have

m .cpyi.:; 5, (

Substituting the value Cp, obtained from expression (5), into expression (4) we obtain an expression for determining the tangential component of the cutting force on individual cutters

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As can be seen from the expression (6), the proposed method allows determining the tangential component of the cutting force P "separately on each cutter according to the values of the load on the machine spindle, the radii of processing, feeds per revolution and the electrical conductivities of the cutter-part contacts; the need to periodically change the feed per revolution of the incisors. The speed is on the order of and limited by the speed of the sensors of the processing radius, feed, the electrical conductivity meter of the cutter-part contact, as well as the speed of the computing device that implements the expression (6) and is hundredths of a second.

The high speed of the proposed method allows to increase the measurement accuracy at high frequencies (over 0.1 Hz), fluctuations of the cutting forces by eliminating the smoothing of their amplitude oscillations.

The values of the exponents K. Ij and, included in expression (6), for various combinations of materials

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cutter and parts vary insignificantly, for example, when machining superalloys EI69698VL with hard alloy 5 VK6M X - 0.038; IJ 0.337, Z 1,516, and in the processing of steel OCHNZTSbL carbide cutter

T15K6 X - 0.023; U 0.391;

7 1,741.

0 Small values of X are characteristic and

for other combinations of part and cutter materials and practically the influence of the cutting speed on the measurement results can be neglected (X 0).

5 The method is carried out as follows.

During the cutting process, the load on the machine spindle is measured (the cutting power and the spindle angular velocity,

0 torque), the machining radius and the feed per revolution of each of the cutters in operation and the electrical conductivity of the cutter contacts is detailed. Using the measured values of these five parameters, in accordance with the expression (1), the current value of the tangential component of the cutting force P,.,

The device works as follows.

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In the process of cutting through the cutter-part contacts, an alternating current of the same magnitude is applied to all contacts, the resistor 10 closes across the circuit. Cutter 2 - part 4 - power current collector 11 - transformer 12, The same values of these currents are achieved by equal resistance of resistors R having the value is 2 orders of magnitude than the other resistances of the secondary circuit of the transformer 12, including the contact resistance of the cutter - the detail. Indicative values

1 Ohm resistors, and the transformer secondary winding voltage is 12 1V.

The voltage drop on each contact cutter - detail (U ,, Ll2

0, caused by the flow of electric current and inversely proportional to the electrical conductivity of these contacts, is removed from the cutters 2 near the cutting edge, and from part 4 5 through the measuring current collector 3, and is sent to the input of the block 1 of ac amplifiers. The amplified voltage from the output of block 1 of amplifiers is fed to the input of block 5 of calculation, to the other inputs of which signals from the outputs of block 7 of processing radius sensors, block 8 of feed sensors per revolution and torque sensor 9 are supplied. JU block 5 calculations in accordance with the expression o .. L. hGGGY. The calculation of the tangential component of the cutting force is made. Separately for each tool. If one or two cutters stop Reaan and the cutter makes contact, the part of these cutters, the voltage taken from these cutters becomes equal to the voltage at the output of the transformer 12, which is about 2 times higher than the voltage at the contact of the cutter - the part at the presence of the cutting process. Jari thresholds device 6 disables the corresponding channel from the calculation process in block 5 of the calculation. The proposed method for measuring the cutting saw during multi-cutting turning as compared with limestone has a much higher 4,6 fast action (approximately by 2 orders of magnitude), which makes it possible to use it in automatic control systems (ACS) as force parameters of the cutting process when processing workpieces with sharp fluctuations in allowance both in length and around the perimeter of the workpiece. The use of ACS by power parameters on lathes when roughing parts from casting, forgings, as well as with a complex profile increases the productivity of machines by 20–60%, increases equipment reliability and creates conditions for complex automation of the machining process. Depending on the cost of the machine, the annual economic effect of using the ACS by the cutting process is from 2,000 to 10,000 rubles. on one machine. In addition, the proposed method does not require a periodic change in the reversing tool feed alternately on each cutter, which does not reduce productivity (based on technological considerations and cutter strength, the feed change is possible only downwards) and allows the method to be used in multi-cut turning with one caliper, when alternately changing the feed of the incisors is not possible. / 2

Claims (1)

METHOD FOR MEASURING THE TANGENTIAL COMPONENT OF CUTTING FOR MULTI-CUTTING TURNING, which consists in measuring the load on the spindle of the machine, machining radii and feeds per revolution, including the fact that, in order to increase speed, they additionally measure electrical conductivities contacts the cutter is the 'part and determine the tangential component of the cutting force on individual cutters according to the expression where M - cutting power; G) is the angular velocity of the spindle · la; V *; - respectively, the current processing radius and feed per revolution of the j-th cutter; Q; - electrical conductivity of the ίth contact cutter - part; η is the number of simultaneously working incisors.