SU896599A1 - Device for regulating moisture-content of clay rod of single-motor press - Google Patents

Description

one

The invention relates to the automation of production processes, in particular, to devices for automatically controlling the molding process of coarse ceramics on single-gig press presses.

A device for controlling the moisture of a clay beam is known, which contains a sensor placed in front of the forming head, a tachogenerator connected kinematically to a moving bar, an amplifier, to the inputs of which the signals of the transducer and tachogenerator are given,. an actuator controlled actuator associated with a regulating member for supplying a moistening liquid 1.

A disadvantage of this device is the low reliability of the sensor operating in a moving stream of abrasive mass. Although the dynamic qualities of the control system are somewhat improved due to the presence of a mass flow correction, but a step-up reducer is needed, the presence of a rotating machine in the control loop reduces reliability and weight mass correction at the output (rather than the input) gives an improvement of the dynamic parameters of the control system only with limited within narrow limits change in the flow of the molding material.

Closest to the proposed

5 by its technical essence. is a device for adjusting the plasticity of the clay mass. In it, the pressure sensor signal of the molding material is converted and fed to

The 10 input of the correction device, which forms the proportional-integral law of regulation, is fed to the input of the correction device and a reference signal. The output signal of the rectifier's corrector 15 is summed at the input of the proportional regulator with the reference signal and a correction signal proportional to the total current of the mixer motor. Output

20, the regulator signal is applied to the input of a water or steam metering device (at high humidity, a dry powder). The current correction of the mixer motor is advanced, which allows a significant

improve the dynamics of the regulation system in comparison with the above analogues 2. However, this device has serious drawbacks:

30 the reliability of the sensor is low, the total current of the mixer motor is non-linear as a function of humidity (or plasticity) and performance, and its range does not change when load changes, reducing: control accuracy. In addition, with a single-motor drive, the press has a leading signal determined by the load created by the mixer, does not exceed 30% of the total signal, which also reduces the control accuracy and degrades the dynamic characteristics.

The purpose of the invention is to improve the reliability and accuracy of the device.

The goal is achieved by the fact that a device for controlling the humidity of a single-engine press clay clay bar, containing a charge weight sensor mounted on the feeder, the first comparison element, to one of the inputs of which the first unit is connected and to the output through the regulator and the executive mechanism of the humidifier body, as well as connected to the power supply circuit of the electric drive of a single-motor press a current transformer and a second setpoint device connected to the second input of the first comparison element through successively connected amplifier and second reference element, contains a voltage transformer connected in series, the input of which is connected to the power supply circuit of the electric motor of a single-motor press, and an active current sensor, as well as connected to the second input of the second comparison element, a series-connected measuring transducer and a dynamic equalizer, and the output of the measuring transducer is connected also to the third input of the first element of the comparison, and the input to the output of the weight sensor of the charge

The drawing shows the scheme of the proposed device.

The device contains a single-motor press 1 with a gearbox 2 and an electric drive 3, the supply circuit of which includes the primary windings of the current transformer 4 in one of the phases and the voltage transformer 5 between the other two phases, the secondary windings of the current transformer 4 and the voltage transformer 5 are connected to the inputs sensor 6 active current. The output of the sensor 6 active current together with the output of the second unit 7 and the dynamic equalizer 8 are connected to the input of the amplifier 9, the output of which together with the outputs of the first unit

10i measuring transducer

11 are connected to the input of the regulator 12 The output of the sensor 13 for the weight of the charge set on the feeder 14 is connected to the probe of the measuring converter 11, and the output of the regulator 12 is connected to the actuator

15 connected to the regulator of the humidifier 16.

The device uses a leading corrective signal from the charge weight sensor 13 on the feeder 14, converted by the measuring transducer 11. At a constant speed of the tape feeder 14, this signal is proportional to the press capacity (the amount of the processed charge). The main signal proportional to the performance and viscosity of the set is the signal from the output of the active current sensor b, the inputs of which are connected to the secondary windings of the current transformer 4 and the transformer 5 voltage of the electric drive 3. Here the known active current sensor is used, the principle of which is based on that the inductive resistance of the magnetization circuit of the motor does not depend on the load. Therefore, the voltage transformer 5 is turned on so that the secondary voltage vector is directed opposite to the reactive component vector of the secondary current transformer 4 current and compensates for it, and the output voltage of the active current sensor 6 is proportional only to the active component of the motor current 3. In this case, when the load changes, the signal from the output of the sensor b varies in a much wider range than the secondary current of the current transformer 4, which allows to increase the sensitivity of the circuits and sledovatelno, control accuracy.

The device works as follows.

In the absence of a mismatch between the signals from the sensor 6, the setpoint 7 and the dynamic equalizer 8, there is no signal at the output of the amplifier 9. If at the same time the press performance corresponds to the set one, then there is no mismatch between the signals of the setting device 10, the measuring converter 11, and the weight sensor 13. At the output of regulator 12, the signal is absent, and regulator 16 remains in the rest position. The supply of humidifier (steam or water) is constant.

If the charge supply is increased, a mismatch signal appears between the signals of the measuring transducer 11 and the setting device 10, and the supply of the humidifier will immediately increase. According to the load of the electric drive 3, the degree of supply of the humidifier to the amplifier 9 will then be adjusted, at the same time the setting of the amplifier 9 by the dynamic corrector 8, the transfer characteristic of which is equivalent to the transfer characteristic of the object, i.e. press 1 with a single-motor drive.

The need for a dynamic corrector 8 follows from the following considerations. When the charge supply changes, even at its optimum humidity, the load on the electric drive 3 changes, the nature of its change does not coincide with the character of the change in the charge supply, since both the mixer and the press chamber of the press 1 with respect to the electric drive 3 with disturbances on loading inertial links with delay. Obviously, the comparison signal for comparison with the signal proportional to the active component of the current, at the input of the correction device 9, should change as well as the signal from the output of the active current sensor b at the optimum moisture content of the charge.

I

The second setting device 7 is necessary to compensate for the active component of the no-load current. Naturally, under these conditions, for a constant comparison of the load of the electric drive 3 with the necessary dynamic equalizer 8, it must have a transfer function compatible with the variable part of the transfer function of the press. Similarly, the device fulfills the reduction of the supply of the charge. When the moisture content of the charge changes, it will work out the mismatch with some delay.

The use of the proposed device improves product quality, improves equipment performance, reduces unproductive material losses.

Claims (2)

1. Author's certificate of the USSR W 265771, class, G 05 D 22/02, 1960. 2.Patent UK No. 1459822 cl. G 05 D 11/13, published 1976 (prototype).