SU1680782A1 - Device for continuous annealing of current-conducting wires by alternating current - Google Patents

Abstract

The invention relates to heat treatment of materials, in particular to the heat treatment of wire. The purpose of the invention is to improve the quality of annealing. The installation of continuous annealing of current-carrying conductors with alternating current contains a transformer with a secondary winding, a thyristor controller along the primary winding of the transformer, a control unit of the thyristor controller, and a comparison unit. New in the installation is an additional feedback transformer, the primary winding of which is connected to the contact rollers using sliding contacts interconnected by a high-resistance wire passing through the window of the magnetic circuit of the power transformer, and the secondary winding is connected to the input of the thermocouple. connected to the second input of the comparator unit, and the third input of the comparator unit is connected to the source of the bias voltage, while the magnitude of the bias voltage is That the stationary conductor at zero speed is heated to a predetermined annealing temperature. 1 il.

Description

The invention relates to the heat treatment of materials, in particular to the heat treatment of wire by passing a current directly through the product.

The purpose of the invention is to improve the quality of annealing.

The drawing shows a block diagram of a plant for the continuous annealing of conductive veins with alternating current.

The installation contains a single-phase power transformer 1, contact guide rollers 2 with sliding contacts a and b interconnected with a high-resistance wire 3 through the window of the power transformer 1, a measuring transformer 4 of the feedback, thermal converter 5, an amplifier

6 DC, thyristor controller 7, comparison unit 8, sweep speed sensors consisting of a tachogenerator 9 and converter 10, timing controller 11, a timing controller and a bias voltage source 12.

The installation works as follows.

The conductor core (single-wire or multi-wire) is annealed, which forms the secondary closed coil of the power transformer 1, continuously moving at a given pressing speed. The linear motion speed is measured with the help of a tachogenerator 9 and a converter 10 and in the form of a constant voltage signal Uv f (V) is fed to

About 00

ABOUT

Vj

00

Yu

input block 8 of the comparison. In the same polarity, the bias voltage signal 1) 0 is supplied to the other input of the comparator unit. Summing up, these signals are amplified and through the thyristor controller control unit 11 is fed to the input of the thyristor controller 7, which carries out phase control of the power thyristor key (not shown), at which the turning-on angle of the power thyristors (including anti-parallel) is controlled depending on the control voltage Uy Uv + U0. The magnitude of the voltage across the primary winding of a power transformer is in this case a function of the turn-on angle of the power thyristors, i.e. Uy function. On the closed coil, which forms the secondary winding of the power transformer, an emf is induced, which produces an annealing current in the annealed coil.

The voltage from the contact rollers 2 is removed using sliding contacts (points a, b) and is fed to the input of the measuring transformer 4 feedback, the output of which is loaded on the input-thermoconverter 5, for example, type TBB-3, TVB-4, TVB-3 9, etc. The thermal converter is in essence an electrothermal quad, and in this thermal converter a quad and a low-pass filter (FCF) are continuously connected, i.e. integrator. The instantaneous power released in the heater is proportional to the square of the input current, and because of the heat capacity of the heater, its temperature is proportional to the current average power. The limit of permissible basic thermal converter error is 0.1%. The most important quality of the converter in this circuit is that the conversion factor does not depend on the shape of the input signal consisting of sinusoidal segments.

Thus, using a measuring transformer and feedback and thermal converter 5, the emf at the annealing coil or the annealing voltage is measured with a high degree of accuracy. The high resistance wire 3 passing through the window of the power transformer 1 ensures that the voltage between the contact rollers 2 is constant in the event of partial contact breakdown on the rollers during movement, when the annealed core is contaminated, and also when the closed turn is completely broken. An increase in the load current causes an increase in losses due to the scattering flux, however, the voltage between points a and b is independent of the cross section of the annealed core and is determined only by the magnitude of the pulling speed, i.e. voltage on

tachogenerator 9. The voltage of the secondary winding of the measuring transformer and feedback is fed to the input of the thermal converter and then through the DC amplifier 6 to the comparison unit 8 in polarity, opposite to the polarity of the speed gauge Uv.

Thus, the control algorithm is determined by the ratio

UTTTJ const A

where Do is the bias voltage providing, when Uv 0, the core is heated in a stationary mode (with a fixed core) to the annealing temperature.

Indeed, in the scheme

Watzh (Uv + Uo - Ki u2otzh) -K2,

where Ki is the annealing voltage conversion coefficient (Cot) on the annealing coil into a feedback signal proportional to the square of the effective value of this voltage;

K2 is the conversion factor of the output signal of the comparison unit 8 to the annealing voltage.

Considering that the gain of the thyristor controller control unit 11 is large (103-104), we can assume that the difference

Uv + Uo-k-i and 20tzh ,,

those.

Uv + U0 Ki and 2otzh.

After simple transformations, the law of regulation is generally determined by the ratio

V + l & JKo

- d m

as when V K2 (U0 - Ki U otzh0)

,

where it is the annealing voltage on the contact rollers with a fixed core, i.e. at

A is a constant value determined by the ratios of the conversion in the channels for measuring the speed of pulling, the control unit of the thyristor controller, and the feedback.

This ratio is maintained throughout the entire range of regulation, it is obvious that

u0tzh U

 ozh.

The value of -r- U Annealed, and the annealing voltage calculation with increasing speed according to the law

iotzh VAV + and $ tzh0

As the speed grows, the influence of the constant component U decreases exponentially, while 11tx tends to

  vW, T.e.A

(known regulation law).

In practice, the value of U0 is set such that when V, the quality of annealing meets the requirements of the standard (bottom setting).

The top adjustment is made at the highest speed, and the conversion factor of the converter 10 (factor A) is set to such a value that, at the highest speed, the quality of annealing is the same as with V -Y. With such a setting, at a speed of V 30 m / min, the influence of the component 112otzh0 in the regulation law is practically not felt. If the limit of variation of velocities or annealed sections is insignificant, then in such a simpler case it is sufficient to position the feedback winding in the plane of the annealed screw (inside its contour). In this case, the voltage on the feedback winding changes in the same way as the EMF on the annealing coil as a function of the voltage of the primary winding of the power transformer and the load current, keeping the law of regulation and to the expression 1 &

1 | .2

A1

-.

U + -NЈtzh

All sections and speeds. In this case, there is no need to install a feedback transformer.

The use of the proposed installation of continuous annealing of conductive veins with alternating current in comparison with the known ones provides the following advantages:

maintaining the specified law of regulation over the entire range of speeds (starting from and above) and sections tO-120 mm2, as well as high accuracy and stability

the measurement of the square of the current value of the annealing voltage with its non-sinusoidal nature provides a high temperature stability at

5 final annealing section;

the annealing mode when changing the speed or changing from one section to another is set automatically and does not require adjustment;

10, the compensation of disturbing influences (voltage variation of the supply network, fluctuations of the resistivity of the material of the annealed wires, the degree of contamination, etc.) also occurs automatically by stabilizing the voltage on the contact rollers as a result of the functioning of the feedback circuit.

Claims (1)

Invention Formula 20 Installation of continuous annealing of conductive veins with alternating current, comprising a transformer with a secondary winding in the form of an annealed wire turn, a thyristor controller along the primary winding of the transformer, a control unit of the thyristor controller, a comparison unit, the output of which is connected to the control unit, and one of the inputs - with a speed sensor for threading, different to 30 by the fact that, in order to improve the quality of annealing, it is equipped with a thermal converter, an amplifier and a bias voltage source, as well as a measuring transformer of feedback, the primary 35 the winding of which is connected to contact rollers, for example, using sliding contacts interconnected by a high resistance wire passing through the window of the power transformer magnetic circuit of the mat, and the secondary winding connected to the input of the thermal converter, the output of which through the amplifier is connected to the second input of the comparison unit and the third input of the comparison unit is connected to a source of bias voltage 45. 9