RU115277U1 - NEXT DRIVING DRIVE FOR METAL CUTTING MACHINE - Google Patents

Abstract

A servo drive of a metal-cutting machine containing a DC motor connected to an AC-to-DC converter, a pulse-phase control system, the output of which is connected to the control input of the converter, a speed controller, a first comparator whose output is connected to the input of a pulse-phase control system, a sensor speed, the input of which is 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 generator, and the output to the second input of the first comparator, a device for diagnosing the state of the cutting tool by cutting forces, consisting of a dynamometer , the input of which is kinematically connected to the engine, and an indication unit connected to the output of the dynamometer, characterized in that it is equipped with a second adder, second and third comparators, first and second delay lines, while the output of the dynamometer is connected to the first input of the second adder, to the second entrance ohm of the second comparator and with the input of the first delay line, the output of the speed generator is connected to the second input of the third comparator and to 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 the 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.

Description

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 system, the output of which is connected to the control input of the converter, and the input is connected to a voltage regulator. When using such a drive, a low-voltage signal is supplied to the pulse-phase control system using a setter. In response to it, the system 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. This drawback is largely devoid of an analog drive, described, for example, in the work of V.L. Sosonkin and others. Program control of machines. - M.: Mechanical Engineering, 1981, p. 119, Fig. 2.11. " To a lesser extent, it responds to fluctuations in the moment of resistance, and therefore the field of its application is wider than that of the previous one.

The second drive - the analogue contains a DC motor connected to an AC to DC converter, a pulse-phase control system, the output of which is connected to the control input of the converter, a comparator whose output is connected to the input of the pulse-phase control system, 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.

When operating this analog drive with the help of a speed adjuster, a control signal is supplied to the drive. This signal, passing through the comparator, sets the phase and phase control system to a certain phase shift of the output pulses in time. The pulses are fed to the control input of the AC to DC converter and, depending on their phase, cause the converter to supply a certain constant voltage to the motor. The engine rotates at a certain speed, and the speed sensor kinematically connected with it gives a signal characterizing the speed. This signal, arriving at the first (subtracting) input of the comparator, is subtracted from the signal coming from the speed setter, as a result of which the difference of these signals is supplied to the pulse-phase control system. It provides the desired engine speed at a given load. If the load on the engine (moment of resistance) increases, then the engine begins to lose speed. The speed sensor will give a signal smaller than before. The difference between the signal coming from the master and the speed sensor increases. In this case, the signal at the output of the comparator increases, and, ultimately, the engine speed increases. In the case when the load on the engine falls, its rotation speed increases. The speed sensor generates a larger signal than before. At the output of the comparator, the signal difference is smaller than before, and the engine slows down. Thus, the engine speed during fluctuations in the moment of resistance remains approximately constant, corresponding to a specific signal from the master.

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 vibrations 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 we have adopted as a prototype. It contains a DC motor connected to an AC / DC converter, a pulse-phase control system, 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 system, 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 device for diagnosing the state of the cutting tool nta by cutting forces, consisting of a dynamometer, the input of which is kinematically connected to the engine, and an indication unit connected to the output of the dynamometer, while the second input of the adder is connected to the output of the dynamometer, and the output to the second input of the comparator.

When using the prototype drive using a master, a signal is introduced into the drive that provides the required engine speed at a given load. In this case, the speed sensor generates a signal characterizing the speed of the engine, and the dynamometer - a signal characterizing the moment of resistance on its shaft, which is a function of the cutting force when machining this part on a machine. The signal from the dynamometer is fed to the display unit and provides the operator with information about the status of the cutting tool. At the same time, it enters the adder and adds up with a signal from the setter. The signal from the output of the adder is fed to the second input of the comparator. The signal from the speed sensor is received at the first input of the comparator and is subtracted from the signal received at the second input. As a result, there will be a signal at the output of the comparator, which, by setting the operating mode of the pulse-phase control system and voltage converter, provides the required motor speed. If the engine speed decreases due to an increase in cutting force (and hence the resistance moment), then the speed sensor will reduce the output signal and the output signal of the comparator increases, which will lead to a reverse increase in speed. If the engine speed increases due to a decrease in cutting force (resistance moment), then the speed sensor will increase its output signal, at the output of the comparator the signal will decrease, and the engine speed will accordingly decrease. At the same time, if the moment of resistance on the engine increases and the engine starts to reduce speed, the dynamometer will add its signal through the adder to the signal of the master, at the output of the adder the signal will increase, at the output of the comparator, which will contribute to the reverse increase in engine speed. If the resistance moment on the engine drops, then the dynamometer will reduce the signal at the output of the adder, and the signal at the output of the comparator will decrease the increasing engine speed. Thus, the combined action of the speed sensor and the diagnostic tool state of the instrument will provide a decrease in engine speed if it has increased, or its increase if it has decreased. The specified combined action will lead to a decrease in speed fluctuations during load fluctuations.

Despite the fact that the prototype drive provides higher speed stability than the 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).

The task of creating the proposed utility model is to eliminate this drawback of the prototype, i.e. Improving the performance of an existing servo drive. This problem is achieved by the fact that the servo feed drive of a metal cutting machine containing a DC motor connected to an AC / DC converter, a pulse-phase control system, 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 system, a speed sensor, the input of which is kinematically connected to the engine, and the output is connected to the first input of the first comparator, the first sum a torus, the first input of which is connected to the speed control unit, and the output - to the second input of the first comparator, the cutting tool diagnostic tool for cutting forces, consisting of a dynamometer, the input of which is kinematically connected to the engine, and an indication unit connected to the dynamometer output is additionally equipped the second adder, the second and third comparators, the first and second delay lines, while the output of the dynamometer is connected to the first input of the second adder, with the second input of the second comparator and with the input of the first the delay line, the output of the speed controller is connected to the second input of the third comparator and 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.

A diagram of the proposed servo drive is shown in the figure. 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 system 3, the output of which is connected to the control input of the converter 2, speed controller 4 , the first comparator 5, the output of which is connected to the input of the pulse-phase control system 3, and the speed sensor 6, whose input is kinematically connected to the engine through a mechanical transmission 7 (or maybe directly) m 1, and the output is connected to the first input of the comparator 5. In addition, the drive contains a first adder 8, the output of which is connected to the second input of the comparator 5, a device for diagnosing the state of the cutting tool by cutting forces, consisting of a dynamometer 9, the input of which is kinematically through mechanical transmission 10, connected to engine 1, and an indication unit 11 connected to the dynamometer output, a second adder 12, a second 13 and a third 14 comparators, the first 15 and the second 16 delay line. 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 input of the delay line 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, and the output of the adder 12 under is connected to the third input of the adder 8.

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 encoder 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 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 adder 12 and fed to the adder 8, then to the comparator 5, to the pulse-phase control system 3, the converter 2 and provides the speed ω of rotation of the 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 an increase in cutting force (and hence the resistance moment), 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 arr Tnom 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.

If the moment of resistance on the engine drops, then the dynamometer 9 will reduce the signal at the output of the adder 12, the signal at the output of the comparator 13 will contribute to its reduction, the signal at the output of the adder 8 will decrease, and the increasing speed of the engine 1 will decrease. Thus, the combined action of the speed sensor and the diagnostic tool state of the instrument will provide a decrease in the speed of the engine 1, if it has increased, or its increase, if it has decreased. The specified combined action will lead to a decrease in fluctuations in drive speed during load fluctuations. At the same time, due to taking into account not only the load fluctuations themselves, but also the load fluctuation speed, the reduction in the drive speed fluctuations will be faster. Similarly, due to taking into account not only the change in the driving voltage from the master 4, but also the rate of change of this voltage from the master 4, the proposed drive will accelerate to the required operating speed also faster.

Let us prove the described technical result obtained using the proposed utility model as follows. We characterize the operation of the drive by a 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

U = U ₄ + U ₉ -U ₆ ,

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. It follows that for the prototype

ω = A (U ₄ + D · MC · ω) -B · M,

and further

Assuming that U ₄ changes at some speed and in this case, M changes with speed , for some values of U ₄ = U ₄ ′ and M = M ′ we will have

.

If U ₄ ′ changes to U ₄ ″, and M ′ to M ″, we get

Subtracting ω ′ from ω ″, we obtain a change in ω as a result of a change in U ₄ and M equal to

or

,

which means: a change in the driving signal by ΔU ₄ and a change in the moment of resistance by ΔM leads to a change in ω by Δω.

We turn now to the proposed drive. For him

or

.

this implies

and further

Assuming that U ₄ varies from U ₄ ′ to U ₄ ″ with the same speed as in the previous case, and M changes from M ′ to M ″ also with the same speed as in the same case, we will have

,

or, when U ₄ ″ -U ₄ ′ = ΔU ₄ , M ″ -M ′ = ΔM and Δω = ω ″ -ω ′,

That is, the proposed drive operates with the same speed fluctuations ω as the prototype, or, in other words, is equally stable. But its speed is higher than that of the prototype. Speed is the rate of change of ω with changes in U ₄ and M, or the first derivative of ω, equal to .

Using the formula (*) corresponding to the prototype, we obtain

,

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

.

It is seen that γ ** is greater than γ * by

,

i.e., the speed of the proposed utility model is really higher than the prototype.

Claims (1)

Tracking drive of a metal cutting machine, comprising a DC motor connected to an AC / DC converter, a pulse-phase control system, 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 system, a sensor speed, the input of which is 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 master bore, and the output - to the second input of the first comparator, a device for diagnosing the state of the cutting tool by cutting forces, consisting of a dynamometer, the input of which is kinematically connected to the engine, and an indication unit connected to the output of the dynamometer, characterized in that it is equipped with a second adder, a second and the 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 controller and connected to the second input of the third comparator and to 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 with the second input of the first adder, and the output of the second adder is connected to the third input of the first adder.