Metal deforming – With use of control means energized in response to activator... – Metal deforming by use of roller or roller-like tool element
Patent
1993-08-20
1995-10-31
Larson, Lowell A.
Metal deforming
With use of control means energized in response to activator...
Metal deforming by use of roller or roller-like tool element
364151, 364472, B21B 3700, G05B 1304
Patent
active
054618940
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a feedback control of a hot and/or cold rolling process by means of a process control system, which executes a predetermined rolling program containing the initial and final dimensions, material data, roll temperatures, etc., and has a master system for controlling the setpoint values of subordinate, preferably decoupled, individual control units for the variable functional variables of the individual roll stands, e.g. rolling force, rotational speed, screw-down position [setting], etc. The setpoint values of the control units are determined in a computational operation using model equations, in which prepared and statistically processed measured values of the process variables are substituted, with a converging absolute adaptation of parameters to the actual parameters.
Control systems for hot and/or cold rolling processes, which work with single closed-loop control circuits and parameter adaptation of the model equations to determine the setpoint values of the control units are generally known and are described, for example, in the non-prepublished German Patent Application 40 40 360.2. These types of control systems work most satisfactorily in continuously running rolling processes. What is disadvantageous, however, is that in the event that the requirements change, the time for achieving the new operating state is relatively long. This means that several strips, or the like, could possibly be rolled with faulty dimensions or incorrect temperatures before the new operating state is reached. The reason for this is that the known control system carries out the parameter adaptation with learning steps, i.e., step by step.
SUMMARY OF THE INVENTION
To overcome the disadvantages of the prior art, the present invention specifies a control system for hot and/or cold rolling processes, which in the event of changes in requirements leads very quickly to a product that is within tolerances, in particular to a product that can be utilized immediately after the requirement is changed.
This is done with surprising ease in that in the event of changes in the requirements of the rolling process, particularly in the transition from manual to automatic operation, or of changes in the final thickness, and/or changes in temperature, a relative adaptation of the control system is carried out whereby deviations between the measured values of the process variables and values coming from the preceding rolling process are calculated, based on said deviations set values are calculated with the aid of the model equations and the set point values are supplemented by the set values.
The relative adaptation of control system is achieved which makes it possible to reach the tolerance range for the finished product considerably faster than had previously been possible. This applies particularly to when a new dimension, a new quality or a new structural state is initially rolled in manual operation, or when the rolling program, as is customary, is conceived so as to allow successive roll lots to be staggered according to their differences.
The converging parameter adaptation takes place advantageously as the result of rapid comparisons of the following types. The absolute and relative converging parameter adaptation proceeds from an initial equation of the type:
where r represents the parameters.
The absolute and relative converging parameter adaptation is then continued with equations of the type: ##EQU1## r representing the corrected parameters.
Finally, the absolute and relative converging parameters adaptation is further continued with equations of the type:
so that the variable functional variables of the roll stands are determined from these equations.
With a small amount of computational work, a rapid convergence results in these equations, both for the absolute as well as for the relative adaptation. By using these equations simultaneously for both adaptation processes, it is possible to supplement the program used to carry out the adaptation in an advantageously
REFERENCES:
patent: 3863478 (1975-02-01), Harada et al.
patent: 4407017 (1983-09-01), Zhilikov et al.
Iron and Steel Engineer, vol. 64, No. 10, Oct. 1987, Pittsburgh, U.S., pp. 45-49; W. Smith: Modernization of a tandem cold mill with distributed digital control.
International Federation of Automatic Control, proceedings of the IFAC, 6th World Congress; Boston, 24-30 Aug. 1975; Instrument Society of America, Pittsburgh, Pennsylvania, U.S., 1975; Part 2--Applications; Session 46.1, pp. 1-8; H. W. Seyfried et al.: Application of adaptive control in rolling mill area, especially for plate mills.
Larson Lowell A.
Schoeffler Thomas C.
Siemens Aktiengesellschaft
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