SU420404A1 - DEVICE FOR STABILIZATION OF FORCE CUTTING ON METAL CUTTING MACHINES - Google Patents

Description

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The invention relates to a machine tool industry and is intended for machine tools, for example, universal turning, milling, boring machines, in which a single motor carries out kinematically related main movement and feed movement.

Devices are known for stabilizing the power or cutting force by controlling the feed rate.

In the known device, the kinematic coupling between the velocity box and the feeds is broken, an independent feed drive is introduced, the speed of which varies depending on a given power level or cutting force and on the deviation of actual values from the set ones.

However, an independent feed drive must have a wide range of control, overlapping the entire range of feeds of the machine.

A change in the rotational speed of the engine leads to a change in the minute feed, while the power or cutting force is determined by the reverse feed. This complicates the adjustment of the stabilization system when the number of revolutions of the spindle is changed. Moreover, reconfiguration of the auxiliary drive is usually associated with techniques not familiar to the machine operator: it is necessary to adjust the potentiometers, monitor the readings of the devices, etc.

The additional motor and its control circuit must be large enough to allow the tool to move in all cutting conditions.

Dynamic ejections of force or power

Cuttings caused by sudden changes in the allowances or hardness of the workpiece are processed by reducing the rotational speed of the additional motor. Since the inertia of conventional engines is great, and

Since the time to decrease speed is usually longer than the time constant to increase the speed of rotation, then significant dynamic overshoots are inevitable. The purpose of the invention is to simplify the operation of the device, reduce the range of feed control and reduce the power in the control circuit.

This is achieved by integrating a differential-summing mechanism into the kinematic chain of the machine so that its first input is connected to the output of the gearbox, an adjustable drive is connected to the second input, and the output of the differential-summing mechanism is connected to the input of the box

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In order to improve the dynamic characteristics, the adjustable drive is implemented as a controlled brake clutch, the resistance moment of which is determined by the measured signal connected to the output of the differential summing mechanism and the generator. The speed of the latter depends on the moment of resistance of the brake coupling. The generator is connected to one of the inputs of the differential summing mechanism via a friction clutch.

FIG. 1 shows a kinematic diagram of the device as applied to a universal lathe; in fig. 2 is an electrical circuit for connecting machine elements.

The device consists of a differential-summing mechanism (DSM) 1, one input of which, for example wheel 2, is connected to gear 3 of the output of the gearbox, and the output of DSM, for example drove 4, to the input shaft 5 of the feed box and the adjustable drive.

An adjustable drive consists of a controlled, panrimer, powder brake clutch 6, combining with a water jet 4, and a generator 7, the shaft of which through non-swap 8 and friction clutch 9 engages the wheel 10.

The winding 11 brake clutch 6 is connected to the output of the amplifier 12 signals of the meter 13 force P or power / V.

The excitation winding 14 of the generator 7 is supplied in the usual way from a source of emf. direct current fi and measles 15 is fed by a small source of emf. - EZ through diode 16 and at the same time loaded with resistance 17 through diode 18.

The device works as follows.

At idle caliper stack in the absence of cutting forces, the signal at the output of the amplifier 12 is zero. Accordingly, the moment of resistance, created by clutch 6, is also zero. The moment of idle resistance forces brought to the generator shaft 7 is balanced by the driving moment created by the EZ source so that the wheel 10 is stationary (or rotates at a very low speed). In this case, the carrier 4 rotates the input shaft 5 of the feed box at maximum speed, and the reverse feed rate of the machine’s sunnort is determined by the gear ratio of the feed box.

Obviously, a change in the rotation speed of the shnindel does not cause a change in the reverse feed.

During the processing of the workpiece, a cutting force arises, an electric sigal appears on the output of the meter 13 and the amplifier 12, the clutch 6 creates a braking torque on the carrier 4. As a result, the generator shaft 7 drives the BO rotation at a speed at which the torque of rotation rotates reduced braking torque. Accordingly, the speed of rotation of the carrier and the input shaft of the feed box decreases, the working gear of the machine support decreases.

Selection of the gain of the amplifier 12 and the value of resistance 17 in the core circuit of the generator 7 ensures the necessary proportionality between the increment of the force or the power of the cutting and the variation of the feed that compensates for this increment.

Since the reverse nodach does not change when the spindle revolutions change, the diagonal change of the nodach from the device drive should provide only the increments necessary to compensate for possible

fluctuations and physical characteristics of the workpiece.

Since the control of the feed rate is carried out with the help of the friction clutch 6, the power in the control circuit is small

and significantly less than the required power of self-driving control.

The dynamic ejections of force or power are reduced to small values due to the low inertia of the coupling. In addition, the speed

delaying feed can be increased by briefly forcing a braking torque, for example, by sigpals of the derivative of power or force. At the same time, the fricciopp coupling 9 slips away, against the safety of the DSM from overloads.

The application of the proposed device does not change the usual methods of machine control and cutting modes, which are reduced to switching gear boxes and feeds.

Subject invention

1. A device for stabilizing the cutting force on metal-cutting machines with an adjustable feed drive, controlled depending on the measured cutting force, characterized in that, in order to simplify the operation, reduce the dianazone control knob and reduce power in the control circuit, to the kinematic value of the machine built-in differential summing mechanism so that its first input is connected to the output of the velocity box, an adjustable drive is connected to the second input, and the output of the differential summing mechanism is connected to o input box nodach.

2. The device on n. 1, characterized in that, in order to improve the dynamic performance, the adjustable drive is made in the form of an equilibrated brake clutch, the resistance moment of which is determined by the measured signal connected to the output of the differential summing mechanism and the generator, the speed of which depends on the moment of resistance of the brake clutch connected to one of the inputs of the differential summing mechanism via a friction clutch.