SU710707A1 - Rolled stock thickness automatic control method - Google Patents

Description

one

The invention relates to the automation of rolling production and can be used mainly in rolling strip material from ferrous and non-ferrous metals and alloys, as well as in the chemical and papermaking industry.

A known method of automatically adjusting the thickness of the rolled product, in which the thickness of the rolled product is measured indirectly by the position of the pressure screws and the force of the metal on the rolls, and is carried out by means of the pressing device 1.

The disadvantage of this method is the low accuracy of the adjustment of the thickness of the rolled products.

The closest to the proposed technical essence and the achieved result is a method of automatic adjustment of the thickness of the car, which means that the given thickness of the car is compared with the current car thickness, determined indirectly by the solution of the unloaded rolls and the elastic deformation of the stand during rolling, and when these are misaligned the values change the gap between the rollers until the specified error is eliminated. The thickness of the rolled product in this method is determined by the indications

gauge of metal force on the rolls, the position sensor of the pressure screw and the magnitude of the pressure in the system of hydro-balancing of the support rolls 2.

A disadvantage of the known adjustment method is that when measuring the thickness of the rolled stock, the hysteresis of the stand, which affects the accuracy of adjustment, is not taken into account. Hysteresis in the rolling stand is caused by the presence of frictional forces that occur on surfaces

sliding of cage parts (pillows of rolls, nuts of the pressure screw, splines of the pressure screw) when they are loaded. The measured value and the sign of the hysteresis depend on the installation site of the force meter, on the direction and

the amount of movement of the pressure screws and is 2-8% of the nominal rolling force. The minimum hysteresis value corresponds to the case when the hysteresis is measured by force meters installed on the pillows of the upper support screws, and the maximum case is when the meters are installed above the pressure screw nut.

During the movement of the pressure screws, the hysteresis accumulates. After the stop screw movement ceases, the accumulated hysteresis decreases exponentially to 1.0-0.5%. The fall time depends on the initial hysteresis value and is 0.3-0.8 s.

The neglect of the hysteresis and the dynamics of its development introduces an error in the measurement of the thickness of the rolled products, which can be several tenths of a millimeter.

The purpose of the invention is to increase the accuracy of the automatic adjustment of the thickness of the rolled products.

The goal is achieved by the fact that in the known p.i method of control, based on the comparison of the specified thickness of the rolled product with the current thickness determined by an indirect method according to the measurements of the force of the metal on the rolls, the position sensors on the pressure screw and pressure value in the hydraulic control system rolls, and when these values are mismatched — on the impact on the roll gap before the indicated mismatch is eliminated, the measurement error of the metal gain on the rolls, caused by the hysteresis of the stand, is increased by entering a regulator calculated force which exerts an additional effect on the gap in the rolls.

For the case when the output thickness of the car is more than a given J, the value of the additional force is calculated by

DR kj Рi1т- РН) + (Рн - Р-гек

For the case when the output thickness of the rental is less than the specified

DR

PM +.4 (PM - Rtek). gdep

- additional effort; , - maximum rolling force;

- rolling force at the start

and the process of processing the signal mismatch;.

Rtek.

- the current rolling force kJ, k- ;, | e, 4 - coefficients of proportionality, depending on the installation site of the force meter.

The additional force acts from the moment of the beginning; the process of working out the signal of the mismatch. According to the processing of the error signal processing, the additional action is delayed by the time calculated by the formula:

g

+ k, DR,

Dg 0,3

f where Dg is the delay time;

- coefficient of proportionality;

H

DR

- additional effort.

The proposed method is exemplified.

Example. The strip thickness is controlled by rolling in the stands of a continuous mill - 1700 cold rolling. The cage is characterized by the following constructive constants: the modulus of elasticity of the cage is 450 tons / mm, the maximum force of the rolls is 1500 tons, the thickness of the rolled strip of the strip is 0.4-3.0 mm.

The rolling mode is characterized by the following nominal process data: input thickness — 1.0 mm, misalignment size — 0.2 mm.

The rolling force at the time of the occurrence of the error is measured, memorized and entered into the device for calculating the additional effect, which at (x 00 t, PH 1000 t, kj 0.1, kj 0.2. Equals DP 250 - 0.2 P ..

The equivalent weighting is determined

 450 t / mm (0.55 - 0.00045P ek) mm.

Additionally, the gap between the rollers is changed to eliminate the error. After elimination of the mismatch, the value of Р-1-ек 1100 t ДР 30, delay time Дг 0.66 s.

The impact of the value of the DP 30 is maintained for a time of 0.66 s, after which the impact is eliminated.

Using the method of automatic adjustment of the thickness of rolled metal will reduce the error of automatic regulation by 6%, increase the output of rolled metal with a minus tolerance of 0.5% by 80% of the strip length.

Claims (2)

1. Automation of metallurgical production, Thematic industry collection No. 3, M., Metallurgists, 1974, p. 150-153. 2. Authors certificate of the USSR G 188451, cl. B 21 B 37/00, 1967.