SU1136329A1 - Device for automatic control of process for permanent-subsequent heating of ferromagnetic steel when tempering - Google Patents

Abstract

DEVICE FOR AUTOMATIC CURRENT STATUS through an inductor, characterized in that, in order to increase the accuracy of controlling the temperature of the products and to achieve the disturbance invariance , Said bond phase-sensitive output: the converter to the input of the amplifier; The entered block was implemented according to the search for minimum phase angle. SAE S5 with te QO Tempeckout in FIG.

Description

11 The invention relates to electrothermal and can be used in the heat treatment of long products. An automatic electric mode control of an induction melting furnace is known, comprising current sensors, voltage sensors and a phase sensor connected to it with a memory device, automatic control of excitation, matching the generator with the load circuit. and switching a capacitor battery, with the outputs of current and voltage sensors connected to diodes through diodes with control of the exciter control unit H and through AND gates to the input matching block u, This controller allows to increase quality control excited spinning, extend the life perevklyuchateley, capacitors. A known installation for the automatic regulation of the process of continuous-sequential induction heating of ferromagnetic steels, comprising current and voltage sensors of the inductor, the outputs of which are connected to the inputs of the phase-sensitive (Converter connected to the amplifier input, the output of which is connected to the control input of the actuator). The mechanism for moving the product through the inductor 2j. The known device allows to improve the quality and accuracy of adjusting I hardening of parts made of ferromagnetic steels. However, tempering of such parts using these devices does not allow to obtain the quality of heat treatment required by modern technology, which is explained by the fact that the tempering temperature corresponds to the mine dependence of the inductor phase angle on temperature. Therefore, regulation based on comparison with the reference angle in this situation leads to ambiguity. In addition, this dependency region is especially susceptible to the influence of disturbances - voltage instability and the frequency of the power supply of the inductor, the diameter of the part. The purpose of the invention is to improve the accuracy of temperature control of products and achieve perturbation invariance. 9 This goal is achieved in that the device for automatic control of the process of continuous sequential induction heating of ferromagnetic steels during tempering, containing current sensors and inductor voltage, the outputs of which are connected to inputs of a phase-sensitive converter connected by an output with an amplifier input, the output of which is connected to a control input of an actuator Moving the products through an inductor, the connection of the output of the phase-sensitive converter to the amplifier input is made through the input block of the search for the minimum of the phase angle. Figure 1 shows the dependence of the phase angle of the inductor on the temperature of the heated product; Fig.2 is a block diagram of the device; FIG. 3 shows examples of the implementation of a phase-sensitive converter and a phase angle minimum search block. The device comprises an inductor 1, to which the inductor current sensor 2 and the voltage sensor 3 are connected. The outputs of sensors 2 and 3 are connected to a phase-sensitive transducer 4, which, through a block 5 for finding the minimum phase angle of the inductor and an amplifier, is connected to the input of the actuator 7 for moving articles 8 through inductor 1. The phase-sensitive transducer 4 can be performed in the following way. At the inputs of the converter, there are direct current operational amplifiers (OUPT) 9 and 10, whose outputs through capacitors 11 and 12 are connected to the inputs of the first RS flip-flop 13, followed by an active smoothing filter on elements 14 - 17. At the input The unit 5 for finding the minimum phase angle is two analog; keys 18 and 19, the outputs of which are through memory elements, executed in one channel on elements 20 and 21, and in the other on elements 22 and 23, where 20, 22 are capacitors, and 21 - 23 OPTs, connected to the OPT 24. Outputs of the OPT 24 are connected to the first through the elements NE-25-27 th input element And 28, the output of which is connected to the input of the counting trigger 29. To the output of the trigger 29 are connected to the input element 30 and

the first input of the assembly of the two elements IS-HE 31, the outputs of which are connected to the inputs of the counter 32 connected to the digital-to-analog converter 33. The output of this converter 33 serves as the output of the block 5 for searching the minimum of the phase angle.

A clock pulse generator on the IS-NE 34 - 36 elements through the IS-NE 37 element, capacitors 38, 39, and resistors 40 and 41 are connected to the inputs of the second RS flip-flop 42, the inverse output of which is connected to the input of the IS-26 element , and direct - to another input element 26 and through the capacitor 43 to the second input element And 28. Output -. The capacitor bridges 38 and 39 are connected to the inputs of the NAND element 44, connected via the element 45 per core, to the inputs of the assembly 31.

The operation of the device is based on the following laws: the minimum of the function ((Q) (Fig. 1) corresponds to the optimum tempering temperature of the parts, and the minimum position is invariant to the tuning of the oscillating circuit consisting of the inductor and compensating capacitors, the diameter of the inductor voltage instability The presence of an extremum in dependence a (9) is explained by the fact that during heating an increase in the electrical resistivity of the steel occurs, and the magnetic permeability initially remains almost unchanged. This reduces the phase angle. The decrease in magnetic permeability as the temperature approaches the temperature of the magnetic transformations is stronger than the increase in resistivity and the phase angle begins to increase. As can be seen from the graph in Fig. 1, the transition is quite smooth. Therefore, control in the mode of: stabilizing the phase angle on this: the section, even with a slight change in the CpCS dependence), due to the effect of interference, causes significant changes in the eratury. With manual: maintaining the minimum phase angle of the inductor it was possible to ensure the accuracy of maintaining the temperature within + 15 ° C. A minimum of the phase angle of the inductor is furthermore desirable from the point of view of ensuring the best operating conditions of the supply network.

The device works as follows.

Signals in the form of alternating voltage from the outputs of current sensors 2 and voltage 3 are fed to the inputs of the phase-sensitive converter 4. The voltage at the output of the phase-sensitive converter 4 is proportional to the phase angle between the current and the voltage of the inductor to the phase angle of the inductor. From the output of the phase-sensitive converter 4, the signal is fed to the input of the minimum search unit of the phase angle of the inductor 5. The output of the block 5 is connected to the input of the amplifier 6, which fills the actuator 7, which provides movement of the part 8 relative to the inductor 1 so that the value of the phase angle of the inductor is close to the minimum.

The voltage sensors 3 and current 2 are voltage and current transformers, respectively. Blocks 4 and 5 can be implemented, for example, as shown in FIG. Their work is as follows.

The sinusoidal signals from the current transformers 2 and voltage 3 are fed to the inputs of direct current operational amplifiers (OUPT) 9 and 10, which play the role of zero-organs. From the PMTT outputs 9 and 10, square-wave pulses differentiated with the help of capacitors 11 and 12 control the operation of the RS-trigger 13. The pulse duty rate at the output of the trigger 13 is proportional to the phase angle of the inductor. These pulses are smoothed by an active filter on elements 14-17. The cut-off frequency of this filter is much lower than the frequency of the supply voltage of the inductor. Thus, at the output of the filter, there is an analog signal proportional to the phase angle of the

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. The unit 5 for searching the minimum of the phase angle of the inductor implements a continuous search with a reverse. The TcI generator of new pulses, performed on the AND-NE 34-36 elements, ablates pulses. Using the elements 37-41, two synchronization series are formed that control the operation of the analog switches 18 and 19, the RS flip-flop 42. The memory elements 20-21 and 22-23 memorize the successive values of the inductor phase angle over time. These values are compared using OUGGG 24 and the elements AND-HE 25-27 controlled by the RS flip-flop 42 select the sign of the increment of the phase angle of the inductor over time. An increase in the phase angle of the inductor generates a reverse signal, which, passing through element 28, changes the state of the counting trigger 29 n and the change in the speed of moving the part to the right-sided side begins before the time of the reverse. In order to increase the noise immunity of the system, if the phase angle does not begin to decrease over the period of the clock generator, the reverse is forced by the generator pulse through the capacitor 43 and AND 28 element. The speed is controlled according to the change in the state of the counter 32 and digital-to-analog converter 33 As digital; elements can be used chip 133 11 296 series, OUT1T 140 series, keys 590 series, digital-to-analog converter, 572 series. The amplifier 6 (Fig. 2) is selected depending on the type of actuator 7 (Fig. 2). It is a DC amplifier in the case of a collector motor, or a thyristor converter for an asynchronous motor. The use of the proposed device for automatic control of the process of continuous-sequential induction heating of ferromagnetic steels during tempering will improve product quality, productivity and equipment, and improve working conditions. Product quality is improved by improving the quality of heating parts and more accurate compliance with the temperature regime of heat treatment. Decrease in marriage causes an increase in labor productivity and equipment.

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Claims (1)

DEVICE FOR AUTOMATIC REGULATION OF THE PROCESS OF CONTINUOUS SEQUENTIAL INDUCTION HEATING OF FERROMAGNETIC STEELS AT STARTING, containing current and voltage sensors of the inductor, the outputs of which are connected to the inputs of the phase-sensitive converter connected to the output of the amplifier input, the output of which is connected to the control input of the actuator moving products through the inductor, characterized in that, in order to improve the accuracy of temperature control of products and achieving invariance to disturbances, the indicated connection is phase-sensitive output; converter with amplifier input: implemented through the entered block to search for the minimum phase angle. £ 1L1W32a