Robust band tension control

Patent metadata

Field	Value
Publication number	US-10780474-B2
Application number	US-201716091635-A
Country	US
Kind code	B2
Filing date	Feb 27, 2017
Priority date	Apr 14, 2016
Publication date	Sep 22, 2020
Grant date	Sep 22, 2020

Abstract

A metal band is first rolled in a front and then in a rear (downstream) roll stand of a multi-stand rolling train. A looper between the roll stands may detect a band tension in the metal band. The band tension is supplied to a first and a second tension controller to determine an application additional target value and a speed additional target value. The second tension controller may only determine a value less than or greater than 0, as the speed additional target value, if the band tension is above or below an upper or lower band tension limit. Otherwise, the speed additional target value may be 0. The first tension controller is also supplied with a target tension that falls between the band tension limits. The application additional target value may be used to act on the rear roll stand.

First claim

The invention claimed is:

1. A tension control method for controlling a multi-stand rolling train comprising a front roll stand rolling a metal strip and a rear roll stand rolling the metal strip after the front roll stand, the method comprising:
detecting, by a looper, a strip tension prevailing in the metal strip between the front roll stand and the rear roll stand, the looper applied to the metal strip between the front roll stand and the rear roll stand;
supplying the detected strip tension to a first tension controller configured to determine an adjustment additional setpoint value;
further supplying the detected strip tension to a second tension controller configured to determine a velocity additional setpoint value,
wherein the second tension controller determines a value greater than zero as the velocity additional setpoint value when the strip tension detected is above an upper strip tension limit, determines a value less than zero as the velocity additional setpoint value when the strip tension is below a lower strip tension limit and returns the velocity additional setpoint value to a value zero when the detected strip tension is between the lower and the upper strip tension limits;
adjusting the rear roll stand based on the adjustment additional setpoint value, and adjusting at least one of the front roll stand based on the velocity additional setpoint value with positive sign and the rear roll stand based on the velocity additional setpoint value with negative sign;
supplying a setpoint tension to the first tension controller, wherein the setpoint tension lies between the lower and the upper strip tension limits;
wherein the determining of the adjustment additional setpoint value by the first tension controller is performed according to a determination rule on the basis of a deviation of the detected strip tension from the setpoint tension; and
wherein according to the determination rule a value not equal to zero is set as the adjustment additional setpoint value when the detected strip tension is between the lower and the upper strip tension limits.

2. The tension control method as claimed in claim 1 , wherein the adjustment additional setpoint value is a rolling force additional setpoint value.

3. The tension control method as claimed in claim 1 , wherein the adjustment additional setpoint value is a roll gap additional setpoint value.

4. The tension control method as claimed in claim 3 , further comprising: limiting, by the first tension controller, the adjustment additional setpoint value at the bottom to a lower adjustment limit value and at the top to an upper adjustment limit value; and dynamically determining the lower and the upper adjustment limit values as a function of a rolling force with which the metal strip is rolled in the rear roll stand, and the adjustment additional setpoint value.

5. The tension control method as claimed in claim 4 , further comprising:
raising the lower adjustment limit value when the rolling force, with which the metal strip is rolled in the rear roll stand, exceeds an upper rolling force limit value, and otherwise setting a distance of the lower adjustment limit value from the adjustment additional setpoint value to a predetermined value; and
lowering the upper adjustment limit value when the rolling force, with which the metal strip is rolled in the rear roll stand, falls below a lower rolling force limit value, and otherwise, setting a distance of the upper adjustment limit value from the adjustment additional setpoint value to a predetermined value.

6. The tension control method as claimed in claim 1 , further comprising:
defining the velocity additional setpoint value, by the second tension controller, when the strip tension falls below the lower strip tension limit or exceeds the upper strip tension limit, such that the strip tension is set, respectively, to the lower strip tension limit or the upper strip tension limit.

7. The tension control method as claimed in claim 1 , further comprising holding the looper, by a position controller, at a defined position.

8. The tension control method as claimed in claim 1 , further comprising hot rolling the metal strip in the front roll stand and in the rear roll stand.

9. A non-transitory automated processor-readable medium comprising machine code recorded on the medium, and wherein the code is configured such that when the code is executed by the automated processor, the code controls a control unit of a multi-stand rolling train rolling a metal strip firstly in a front roll stand of the multi-stand rolling train and then in a rear roll stand of the multi-stand rolling train;
wherein a strip tension prevailing in the metal strip between the front roll stand and the rear roll stand, is detected by means of a looper applied to the metal strip between the front roll stand and the rear roll stand;
wherein the processing of the code by the control unit causes:
the control unit to receive the detected strip tension;
a first tension controller of the control unit, to which the strip tension is supplied, to determine an adjustment additional setpoint value;
a second tension controller of the control unit, to which the strip tension is supplied, to determine a velocity additional setpoint value;
wherein the second tension controller determines a value less than zero as the velocity additional setpoint value when the strip tension lies below a lower strip tension limit, determines a value greater than zero as the velocity additional setpoint value when the strip tension lies above an upper strip tension limit, and returns the velocity additional setpoint value to a value zero the strip tension lies between the lower and the upper strip tension limits;
adjusting of the rear roll stand according to the adjustment additional setpoint value, and adjusting of at least one of the front roll stand according to the velocity additional setpoint value with positive sign and the rear roll stand according to the velocity additional setpoint value with negative sign; and
the first tension controller to determine the adjustment additional setpoint value using a determination rule on the basis of a deviation of the strip tension from a setpoint tension, which lies between the lower and the upper strip tension limits,
wherein the determination rule sets a value not equal to zero as the adjustment additional setpoint value when the strip tension is between the lower and the upper strip tension limits.

10. The automated processor-readable medium as claimed in claim 9 , wherein the processing of the code by the control unit causes the adjustment additional setpoint value to be a rolling force additional setpoint value.

11. The automated processor-readable medium as claimed in claim 9 , wherein the processing of the code by the control unit causes the adjustment additional setpoint value to be a roll gap additional setpoint value.

12. The automated processor-readable medium as claimed in claim 11 , wherein the processing of the code by the control unit causes: a lower adjustment limit value and an upper adjustment limit value to be supplied to the first tension controller the first tension controller, limiting the adjustment additional setpoint value at the bottom to the lower adjustment limit value and at the top to the upper adjustment limit value; and causes the control unit to determine dynamically the lower and the upper adjustment limit values as a function of a rolling force with which the metal strip is rolled in the rear roll stand, and the adjustment additional setpoint value.

13. The automated processor-readable medium as claimed in claim 12 , wherein the processi

Assignees

• Primetals Technologies Germany Gmbh

Inventors

• GRüSS ANSGAR
• Kotzian Daniel
• Maierhofer Andreas

Classifications

• B21B37/46

  Roll speed or drive motor control (B21B37/52, B21B37/60 take precedence) · CPC title

• B21B2265/06

  Interstand tension · CPC title

• B21B37/48

  Tension control; Compression control · CPC title

• B21B38/06

  for measuring tension or compression · CPC title

• B21B37/58

  Roll-force control; Roll-gap control {(B21B38/105 takes precedence)} · CPC title