SU1130610A1 - Device for automatically controlling temperature during resistance heating of metal - Google Patents

Abstract

DEVICE OF AUTOMATIC REGULATION OF TEMPERATURE AT ELECTROCONTACT HEATING OF METAL containing a current source connected to contact rollers, temperature sensor, sensor and current setting device, temperature setting device, with the mmator whose output is connected to the current source. characterized in that, in order to improve the quality of heat treatment by increasing the accuracy of temperature control at the exit of the heating zone, it contains additional contact elements, relay elements according to the number of additional contact elements and a speed sensor, generator, switch, computing unit and control unit connected in series, the outputs of which are connected to the inputs of the relay elements, the opening contacts of which are connected between the additional contact elements, the output temperature sensor The second is connected to the second, the input of the switch, another input of the computing unit is connected to the output of the setpoint temperature, and the current sensor is connected to the first input of the adder, the second input of which is connected to the current setting point. 9 Ed

Description

The invention relates to electrocontact heating of wire and can be used for annealing wire. A continuous current annealing of a wire with a current is known, comprising a speed sensor, a wire wire, a control unit and a voltage variation system. In a known installation, with automatic heating by an alternating current directly supplied to a continuously heated product, it is theoretically determined that the temperature of the product rises depending on the temporal value of the movement speed during movement or stopping. As the norm | the ratio is accepted. const, where I is the current flowing through the product. BUT; V is the linear velocity of the movement M- / C lj. In such a scheme, the heating temperature of the product cannot be maintained, since fluctuations in the cross section at a given length and even minor changes, the chemical composition causes a change in the mass of the product being heated, the value of the heating temperature, of course, and the corresponding annealing quality. The closest to the invention to the technical essence is the automatic control device poM..iHu dBiuMdi nnci, nu, the temperature at the electric contact heating of the metal, containing a current source with contact rollers, a temperature sensor, a current sensor, a temperature setting device, an adder, the output of which is connected to current source. In the known device, the influence of the contact resistance between the wire and the rollers is taken into account, since if you reduce or decrease the values of the transition resistance R, the voltage V of the current source I increases or so that V I is const. A disadvantage of the known device is that it does not provide temperature constancy or pressure from the electrical heating zone when the geometrical and physicochemical parameters of the wire change along the heating zone (for example, the diameters of the chemical composition of the wire material). from the moment the second one enters the zone until the first one leaves the electrical heating zone, the first is heated simultaneously by heating the elementary portion of the wire to a predetermined temperature s can cause (e.g., by increasing the diameter) of the second heating to a higher temperature (overheating). The purpose of the invention is to improve the quality of heat treatment by improving the accuracy of temperature control at the outlet of the heating zone. This goal is achieved by the fact that a device for automatic temperature control during electric contact heating of a metal, containing a current source connected to contact rollers, a temperature sensor, a sensor and current setter, temperature setter, an adder, the output of which is connected to a current source, ele; cops, relay elements by the number i of additional contact elements and a speed sensor connected in series, a generator, a switch, a computing unit and a control unit whose outputs are connected to the inputs of relay elements whose disconnecting terminals are connected between the additional contact elements and the temperature sensor output are connected to. the second input of the switch, and the other input of the computing unit is connected to the output of the setpoint temperature, the current sensor is connected to the first input of the adder, the second input of which is connected to the setting current. FIG. 1 shows a block diagram of the device; in fig. 2 is a block diagram of a computing unit; see 3 is a block diagram of a control unit. The device for automatic temperature control during electric contact heating of the metal (Fig. 1) contains a temperature sensor 1, rmbuli & a current source 2 with contact rollers 3 and an adder 4 connected to it, one of the inputs of which is connected to a current sensor 5, the other input of the adder is connected to an output of a current setpoint 6. The device also contains a speed sensor 7, a generator 8, a switch 9, a computing unit 10, 3j 11 a control block 11, the outputs of which are connected to control elements 42 of the relay 13 inputs, and the closing contacts 14 of which are connected to additional contact elements 15. Other input the switch 9 is connected to the output of the temperature sensor 1, and the other input of the computing unit 10 is connected to the output of the temperature setpoint 16. The computing unit 10 (FIG. 2) contains a voltage source 17, four adders 18-21, two log amplifiers 22 and 23 and24 division scheme. The control unit 11 contains a threshold element 25, a switch 26, an integrator 27, comparators 28, delay elements 29, a reference source for the voltage 30 and a voltage divider 31. The device works as follows. The control loop, consisting of an adjustable current source 2 with contact rollers. 3, a summer 4, a current sensor 5 and a current setting device 6, provides a constant current flowing through the heating portion of the wire. The computing unit 10 through the switch 9 periodically receives a signal xj from the temperature sensor 1, which characterizes its heating temperature by additional contact elements 15, the frequency of the signal x being set by the generator 8 and depends on the speed of the wire. To another input of the computing unit 10, a signal y is received from the setter of the 16 temperature. In the computing unit, the length of the additional wire heating section is determined. The transfer function (I) of the computational glint 10 is determined on the basis of solving the heat conduction equation of the moving axisymmetric medium taking into account the temperature measured at the control point (before the first additional contact), as follows: (ex) 1-epr (L pTr e / e,)) the distance from the beginning of the heating zone to the temperature control point; the length of the additional heating section (taking into account E (j); 0 p is the temperature coefficient of resistance; T (U, TSED); Then the temperature, temperature at the controlled point and the initial temperature of the wire are technologically necessary. Introduce the designation Cr оЕппММТ "Y s-e" (k, hedgehog, BM / fii v-Ttco x; transfer function is written as VCn (, enUnevc where B, C, C, K are constant values. Signal, characterizing the length of the additional heating section, enters to the control unit 11, which determines the operating modes of each of the relay contacts 14 of the relay 13 In the closed position of the i-ro contact 14, the i-th part of the additional wire heating section is shunted. Thus, the electric contact heating of the moving wire is conventionally divided into two zones — the main contact (the first roll) and the additional contact ( element 15) and an additional one, the length of which at each moment of time is determined by the state of the keys and depends on the speed of the wire and its I - -. - I temperature in the zone of the sensor 1 temperature. By maintaining the current posture in the heating zone and adjusting its length, and hence the duration of heating of each elementary segment, it is possible to reach a given temperature and exit from the heating zone. . In the device, due to the introduction of additional elements and the control loop of their operation mode, the temperature equalization in the anomalous areas occurs when they fall into the zone between the additional contact bodies, and the temperature in the substrate does not fluctuate. 11306 x. my heating zone. The control accuracy is higher, the more additional contact elements are installed and the smaller the distance between them. 10 When heating a tungsten wire with a diameter of 2.6 mm before drawing, the economic effect is 0.031 rubles. for every kilogram of wire drawn.

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Claims (1)

AUTOMATIC TEMPERATURE CONTROL UNIT FOR ELECTRIC CONTACT METAL HEATING, containing a current source connected to contact rollers, a temperature sensor, a sensor and a current set point, a temperature set point, an adder, the output of which is connected to a current source, which means that in order to improving the quality of heat treatment by increasing the accuracy of temperature control at the outlet of the heating zone, it contains additional contact elements, relay elements according to the number of additional contact elements and connection sequentially connected speed sensor, generator, switch, computing unit and control unit, the outputs of which are connected to inputs of relay elements, the disconnecting contacts of which are connected between additional contact elements, the output of the temperature sensor is connected to the second input of the switch, the other input of the computing unit is connected to the output of the temperature setpoint , and the current sensor is connected to the first input of the adder, the second input of which is g connected to the current setter. ^w 1 . 1130610 ²