RU160849U1 - NEXT DRIVING DRIVE FOR METAL CUTTING MACHINE - Google Patents

Abstract

A servo feed drive of a metal cutting machine, comprising a DC motor connected to an AC / DC converter, a pulse-phase control unit, the output of which is connected to the control input of the converter, a speed control unit, a first comparator, the output of which is connected to the input of the pulse-phase control unit , a speed sensor, the input of which is kinematically connected with the aforementioned engine, the first adder, the first input of which is connected to the speed controller, and the output to the second at the input of the first comparator, a resistance moment sensor on the shaft of the aforementioned engine, made in the form of a dynamometer, the input of which is kinematically connected to the said engine, a resistance moment indication indicator on the shaft of the mentioned engine, connected to the output of the dynamometer, a second adder, second and third comparators, the first and the second delay line, while the dynamometer output is connected to the first input of the second adder, to the second input of the second comparator and to the input of the first delay line, the output of the speed controller is connected to the second input of the third comparator and with the input of the second delay line, the output of the first delay line is connected to the first input of the second comparator, the output of the second delay line is connected to the first input of the third comparator, the output of the second comparator is connected to the second input of the second adder, the output of the third comparator is connected to the second input the first adder, and the output of the second adder is connected to the third input of the first adder, characterized in that it is equipped with a third adder, the output of which is connected to the first input of the first paratora, four

Description

Cutting machine feed drive

The proposed utility model relates to the field of mechanical engineering, namely, to drives of forming movements of metal-cutting machines.

Actuators similar to those proposed are known. These include, in particular, the drive described in the book “V.L. Kosovsky and others. Software control of machines and industrial robots. - M.: Higher School, 1986, pp. 168-169. It consists of a DC motor, an AC to DC converter, the output of which is connected to the motor, and a pulse-phase control unit, the output of which is connected to the control input of the converter, and the input is connected to the voltage regulator. When using such a drive, a low-voltage signal is supplied to the pulse-phase control unit using a setter. In response to it, the block generates pulses shifted in time by phase by one or another value. The pulses are fed to an AC / DC converter (it is powered by a well-known design source) and, depending on their phase, cause the converter to supply one or another rectified voltage to the motor. By setting a specific control signal with the help of a dial, a certain engine speed can be obtained.

The described drive is quite simple, but it has a serious drawback. With significant fluctuations in the load on it (moment of resistance), the speed of rotation of the output shaft of its engine also changes significantly. Under heavy loads, the engine may even stop. As a result, the scope of this drive is very limited. The drive-analogue, described, for example, in the work “V.L. Sosonkin et al. Software control of machines. - M.: Mechanical Engineering, 1981, p. 119, Fig. 2.11 ". To a lesser extent, it reacts to fluctuations in the moment of resistance, and therefore its field of application is wider than that of the previous one.

The second analog drive contains a DC motor connected to an AC to DC converter, a pulse-phase control unit, the output of which is connected to the control input of the converter, a comparator, the output of which is connected to the input of the pulse-phase control unit, a speed controller, the output of which is connected with the second input of the comparator, and a speed sensor, the input of which is kinematically connected to the engine, and the output is connected to the first input of the comparator.

The considered analog drive works more reliably (it is less likely to stop it during overloads), the engine speed that it provides is more stable, and in general it is more efficient than that described earlier. However, he is nevertheless not free from shortcomings. The main one is that a decrease (or excess) of the engine speed in it is detected when it has already occurred. The drive compensates for it, and the speed is restored, however, some of its fluctuations remain. Moreover, in both directions - in the “plus” and “minus” of the face value. They are caused by the inertia of the engine, and the larger it is, the greater the amplitude of the oscillations.

However, there is a follow-up feed drive having a higher stability than the last. This drive is protected by RF Patent No. 96511 of August 10, 2010 and is also an analogue of the proposed one. It contains a DC motor connected to an AC to DC converter, a pulse-phase control unit, the output of which is connected to the control input of the converter, a speed controller, a comparator, the output of which is connected to the input of the pulse-phase control unit, a speed sensor, the input of which is kinematically connected to the engine, and the output is connected to the first input of the comparator, an adder, the first input of which is connected to the speed controller, a resistance torque sensor on the shaft of the said motor A, made in the form of a dynamometer, the input of which is kinematically connected to the engine, and a resistance moment indication unit on the motor shaft, connected to the dynamometer output, while the second adder input is connected to the dynamometer output, and the output to the second comparator input.

Despite the fact that this drive provides higher speed stability than other analog drives, it does not always have high enough speed, i.e. it does not always quickly change the speed of the engine in response to changes in the signal from the speed controller and the signal from the dynamometer (resistance torque sensor). This disadvantage of the known drives lacks a drive protected by Patent No. 115277 and adopted by us as a prototype. It contains a DC motor connected to an AC to DC converter, a pulse-phase control unit, the output of which is connected to the control input of the converter, a speed controller, a first comparator, the output of which is connected to the input of the pulse-phase control unit, a speed sensor, the input of which kinematically connected to the engine, and the output is connected to the first input of the first comparator, the first adder, the first input of which is connected to the speed controller, and the output to the second input of the first mparator, a torque sensor on the shaft of the aforementioned engine, made in the form of a dynamometer, the input of which is kinematically connected to the engine, and a resistance moment indication indicator on the shaft of the aforementioned engine, connected to the dynamometer output, is additionally equipped with a second adder, a second and third comparators, the first and second delay lines, while the dynamometer output is connected to the first input of the second adder, to the second input of the second comparator and to the input of the first delay line, the output of the speed adjuster is connected n with the second input of the third comparator and with the input of the second delay line, the output of the first delay line is connected to the first input of the second comparator, the output of the second delay line is connected to the first input of the third comparator, the output of the second comparator is connected to the second input of the second adder, the output of the third comparator is connected to the second input of the first adder, and the output of the second adder is connected to the third input of the first adder.

However, nevertheless, the described drive does not always provide a sufficiently high speed in response to changes in the signal from the speed sensor.

The task of creating the proposed utility model is to further increase the speed of the drive. This problem is achieved by the fact that the servo feed drive of the cutting machine, containing a DC motor connected to an AC / DC converter, a pulse-phase control unit, the output of which is connected to the control input of the converter, a speed controller, the first comparator, the output of which is connected to the input of the pulse-phase control unit, a speed sensor, the input of which is kinematically connected to the engine, the first adder, the first input of which is connected to the speed controller, and the output is to the second input of the first comparator, the resistance moment sensor on the shaft of the said engine, made in the form of a dynamometer, the input of which is kinematically connected to the engine, the resistance moment indication indicator on the shaft of the mentioned engine, connected to the dynamometer output, the second adder, the second and third comparators, the first and second delay lines, while the dynamometer output is connected to the first input of the second adder, to the second input of the second comparator and to the input of the first delay line, the output of the speed adjuster is connected with the second input of the third comparator and with the input of the second delay line, the output of the first delay line is connected to the first input of the second comparator, the output of the second delay line is connected to the first input of the third comparator, the output of the second comparator is connected to the second input of the second adder, the output of the third comparator is connected to the second input of the first adder, and the output of the second adder is connected to the third input of the first adder, is additionally equipped with a third adder, the output of which is connected to the first input of the first compar a torus, a fourth comparator, the output of which is connected to the first input of the third adder, a third delay line, the output of which is connected to the first input of the fourth comparator, and the output of the speed sensor is connected to the second input of the third adder, with the second input of the fourth comparator and with the input of the third delay line.

A diagram of the proposed feed feed drive is shown in FIG. 1. It includes a DC motor 1, connected to an AC / DC converter 2 (it can be a standard thyristor converter, powered by a three-phase network), a pulse-phase control unit 3, the output of which is connected to the control input of the converter 2, a master speed 4, the first comparator 5, the output of which is connected to the input of the pulse-phase control unit 3, and a speed sensor 6, whose input is kinematically connected to the motor 1 through a mechanical transmission 7 (or maybe directly). In addition, the drive contains a first adder 8, the output of which is connected to the second input of the comparator 5, a resistance moment sensor of the aforementioned engine, made in the form of a dynamometer 9, the input of which is kinematically connected via a mechanical transmission 10 to the engine 1, and a resistance moment indication unit a motor 11 connected to the dynamometer output, a second adder 12, a second comparator 13, a third comparator 14, a first delay line 15, a second delay line 16, a third adder 17, a fourth comparator 18 and a third delay line 19. In this case, the first input of the adder 8 is connected to the speed controller 4, the output of the dynamometer 9 is connected to the first input of the adder 12, with the second input of the comparator 13 and with the input of the delay line 15, the output of the speed controller 4 is connected with the second input of the comparator 14 and with the line input delays 16, the output of the delay line 15 is connected to the first input of the comparator 13, the output of the delay line 16 is connected to the first input of the comparator 14, the output of the comparator 13 is connected to the second input of the adder 12, the output of the comparator 14 is connected to the second input of the adder 8, the output of the adder 12 is connected to the third input of adder 8, the output of the third adder 17 is connected to the first input of the first comparator 5, the output of the fourth comparator 18 is connected to the first input of the third adder 17, the output of the third delay line 19 is connected to the first input of the fourth comparator 18, and the output of the speed sensor 6 is connected with the second input of the third adder 17, with the second input of the fourth comparator 18 and with the input of the third delay line 19.

сигнала U₄, поступающего от задатчика, т.е. скорости его изменения. Указанный сигнал скорости

с выхода компаратора 14 поступает на сумматор 8, подобно сигналу U₄ от задатчика 4, и добавляется к нему. Сигнал с выхода сумматора 8 поступает на вход компаратора 5 и обеспечивает получение требуемой скорости ω вращения двигателя 1 при данной нагрузке. Датчик скорости 6 при работе двигателя 1 выдает сигнал, характеризующий скорость двигателя, а динамометр 9 - сигнал, характеризующий момент сопротивления М на его валу, являющийся функцией силы резания при обработке на станке данной детали. Сигнал от динамометра 9 поступает на блок индикации момента сопротивления двигателя 11 и представляет оператору информацию о состоянии режущего инструмента. Одновременно с этим он поступает на сумматор 12. Он также поступает напрямую на второй вход компаратора 13 и через линию задержки 15 на первый (вычитающий) вход этого же компаратора. Линия задержки 15 задерживает входной сигнал на время dt и на выходе компаратора 13 при изменении М получается сигнал, равный приращению dM сигнала М за время dt. Так же, как и в случае U₄, в данном случае на выходе компаратора 13 получается сигнал, имеющий смысл

, т.е. первой производной М или скорости изменения М. Этот сигнал складывается с М сумматором 12 и поступает на сумматор 8, затем на компаратор 5, на блок импульсно-фазового управления 3, преобразователь 2 и обеспечивает получение скорости со вращения двигателя 1 совместно с сигналами, поступающими на сумматор 8 от задатчика 4 и компаратора 14. Если скорость двигателя из-за возрастания силы резания (а значит, и момента сопротивления) снизится, то датчик скорости 6 уменьшит сигнал на выходе, и сигнал на выходе компаратора 5 возрастает, что приведет к обратному увеличению скорости ω. Если скорость двигателя 1 из-за уменьшения силы резания (момента сопротивления) возрастет, то датчик скорости 6 свой сигнал на выходе увеличит, на выходе компаратора 5 сигнал уменьшится, и скорость двигателя 1 соответственно уменьшится. Одновременно с этим, если момент сопротивления на двигателе возрастает, и двигатель 1 начинает снижать обороты, динамометр 9 добавит свой сигнал через сумматоры 12 и 8 к сигналу задатчика 4. Сюда же добавится сигнал и о скорости возрастания момента сопротивления с выхода компаратора 13 (чем больше скорость возрастания момента, тем больше этот сигнал, и наоборот). На выходе сумматора 8 сигнал, соответственно, увеличится, на выходе компаратора 5 тоже, что будет способствовать обратному возрастанию оборотов двигателя.When using the drive, it is started and accelerated to the operating speed ω with the help of the adjuster 4, gradually increasing the signal at the output of the adjuster U ₄ , for example, according to a linear law. The signal from the setter 4 goes to the adder 8. The same signal goes directly to the second input of the comparator 14 and through the delay line 16 to the first (subtracting) input of the same comparator. Delay line 16 delays the input signal for some time dt. In this regard, at the output of the comparator 14, a signal is obtained equal to the increment dU _{4 of the} signal coming from the setter 4 during the time dt. Essentially, it makes sense of the first derivative

signal U ₄ coming from the master, i.e. rate of change. Indicated speed signal

from the output of the comparator 14 enters the adder 8, like a signal U ₄ from the setter 4, and is added to it. The signal from the output of the adder 8 is fed to the input of the comparator 5 and provides the desired speed ω of rotation of the engine 1 at a given load. The speed sensor 6 during the operation of engine 1 gives a signal characterizing the speed of the engine, and dynamometer 9 - a signal characterizing the moment of resistance M on its shaft, which is a function of the cutting force when machining this part on a machine. The signal from the dynamometer 9 is fed to the display unit of the resistance moment of the engine 11 and provides the operator with information about the status of the cutting tool. At the same time, it goes to the adder 12. It also goes directly to the second input of the comparator 13 and through the delay line 15 to the first (subtracting) input of the same comparator. The delay line 15 delays the input signal for a time dt and at the output of the comparator 13 when changing M, a signal is obtained equal to the increment dM of the signal M during the time dt. As in the case of U ₄ , in this case, the output of the comparator 13 produces a signal that makes sense

, i.e. the first derivative of M or the rate of change of M. This signal is added to the M by adder 12 and fed to the adder 8, then to the comparator 5, to the pulse-phase control unit 3, converter 2 and provides speed from the rotation of engine 1 together with the signals received at the adder 8 from the setter 4 and the comparator 14. If the engine speed decreases due to the increase in cutting force (and hence the resistance moment), then the speed sensor 6 will reduce the output signal, and the output signal of the comparator 5 increases, which will lead to a reverse CB increase speed ω. If the speed of engine 1 increases due to a decrease in cutting force (resistance moment), then the speed sensor 6 will increase its output signal, at the output of comparator 5, the signal will decrease, and the speed of engine 1 will accordingly decrease. At the same time, if the moment of resistance on the engine increases, and engine 1 starts to slow down, dynamometer 9 will add its signal through adders 12 and 8 to the signal of setter 4. A signal will also be added about the rate of increase of the moment of resistance from the output of comparator 13 (the more the rate of increase of the moment, the greater this signal, and vice versa). At the output of the adder 8, the signal, respectively, will increase, at the output of the comparator 5, too, which will contribute to the reverse increase in engine speed.

The signal from the speed sensor 6 goes to the adder 17. It also goes directly to the second input of the comparator 18 and through the delay line 19 to the first (subtracting) input of the same comparator. The delay line 19 delays the input signal for a time dt and at the output of the comparator 18, when changing co, a signal is obtained that is equal to the increment dω of the signal ω during the time dt. As in the case of U and M, in this case, a signal having the meaning dω / dt is obtained at the output of comparator 18, i.e. first derivative co or rate of change co. This signal is added to the adder 17 and fed to the comparator 5, to the control unit 3, the converter 2 and provides a speed ω of the engine 1 together with the signals received by the adder 8 from the setter 4, comparators 12 and 14. If the engine speed decreases, then the speed sensor 6 will reduce the output signal, and the signal at the output of the comparator 5 increases, which will lead to an inverse increase in the speed ω. If the speed of engine 1 increases, then the speed sensor 6 will increase its output signal, at the output of comparator 5, the signal will decrease, and the speed of engine 1 will accordingly decrease.

Let us prove the technical result obtained as a result of the development of the proposed utility model, as follows. Let us characterize the operation of the drive by an approximate mathematical model

ω = A · U-B · M,

where ω is the angular speed of rotation of the engine, U is the signal level at the output of the comparator 5, M is the moment of resistance due to the action of the cutting forces on the engine, A and B are the proportionality coefficients due to the design of the engine. The prototype drive

where U ₄ is the signal level from master 4, U ₆ is the signal level from speed sensor 6, equal to C · ω, where C is the proportionality coefficient due to the design of sensor 6, U ₉ is the signal level from dynamometer 9, equal to D · M, where D is the coefficient of proportionality due to the design of the dynamometer.

Or

It follows that for the prototype

and further

The proposed drive

or

this implies

and further

The value dω / dt, as is well known, characterizes the speed of the drive.

Compare her performance of the proposed drive with a prototype drive. Differentiating the formula (**) corresponding to the prototype drive, we obtain

Similarly, from the formula (***) corresponding to the proposed drive, we obtain

Comparing the formulas for the same values of A, B, C, D and A> B, C, D, as well as for U4 >> U6, U9, which occurs when constructing and operating the drives, it is easy to notice that γ ** <γ * **. Moreover, as the calculations show, the second can exceed the first by more than 2-4 times, which is especially manifested when small, corresponding to the working feeds of the executive bodies of metal-cutting machines.

Claims (1)

A servo feed drive of a metal cutting machine, comprising a DC motor connected to an AC / DC converter, a pulse-phase control unit, the output of which is connected to the control input of the converter, a speed control unit, a first comparator, the output of which is connected to the input of the pulse-phase control unit , a speed sensor, the input of which is kinematically connected with the aforementioned engine, the first adder, the first input of which is connected to the speed controller, and the output to the second at the input of the first comparator, a resistance moment sensor on the shaft of the aforementioned engine, made in the form of a dynamometer, the input of which is kinematically connected to the said engine, a resistance moment indication indicator on the shaft of the mentioned engine, connected to the output of the dynamometer, a second adder, second and third comparators, the first and the second delay line, while the dynamometer output is connected to the first input of the second adder, to the second input of the second comparator and to the input of the first delay line, the output of the speed controller is connected to the second input of the third comparator and with the input of the second delay line, the output of the first delay line is connected to the first input of the second comparator, the output of the second delay line is connected to the first input of the third comparator, the output of the second comparator is connected to the second input of the second adder, the output of the third comparator is connected to the second input the first adder, and the output of the second adder is connected to the third input of the first adder, characterized in that it is equipped with a third adder, the output of which is connected to the first input of the first a fourth comparator, the output of which is connected to the first input of the third adder, a third delay line, the output of which is connected to the first input of the fourth comparator, while the output of the speed sensor is connected to the second input of the third adder, to the second input of the fourth comparator and to the input of the third delay line .

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