Metal deforming – With use of control means energized in response to activator... – Metal deforming by use of roller or roller-like tool element
Reexamination Certificate
1999-10-20
2001-03-13
Tolan, Ed (Department: 3725)
Metal deforming
With use of control means energized in response to activator...
Metal deforming by use of roller or roller-like tool element
C072S011400, C072S014500
Reexamination Certificate
active
06199417
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a tension control method for a rolling stock section located between a front roll stand and a rear roll stand of a rolling train.
2. Description of the Related Art
In accordance with the prior art, slender rolling stock, such as bar steel and wire, is rolled in continuous rolling trains. When in these trains the rates of rotation of successive roll stands do not correspond to the continuity equation which is determined by the constant mass flow, tension or compression build up between the successive roll stands.
Tension and compression in the rolling stock have a negative influence on the cross-section tolerances, particularly the section width. Moreover, compression in the rolling stock leads to instabilities which produce so-called fluttering. In an extreme case, compression in the rolling stock may even lead to material ruptures and interruptions of the operation.
In order to achieve good finishing tolerances and to guaranty a safe rolling process, an efficient tension control is required.
In accordance with the prior art, primarily two control types are used for tension control, i.e., the so-called flow stoppage method and the looping method. For realizing both methods, a minimum distance between stands is required. When the distances between stands are too small, only a manual method of tension control is available in the prior art. By applying an impact or pressure on the rolling stock, the rolling train operator attempts to estimate the tension or compression present in the rolling stock based on his experience. This method of operation is subjective and very imprecise and also unreliable. Moreover, this method can only be carried out in certain time intervals. A control of the tension is not possible using this method.
SUMMARY OF THE INVENTION
It is the primary object of the present invention to provide a tension control method which makes possible a reliable tension control even when the distances between stands are small and the rolling speeds are high.
In accordance with the present invention
a tensioning element with an actual adjusting force is adjusted relative to the rolling stock section, so that the rolling stock section is deflected by the tensioning element by an actual deflection;
the actual adjusting force and the actual deflection are determined; and
a tension existing between the front roll stand and the rear roll stand in the rolling stock section is adjusted such that the actual adjusting force approaches a desired adjusting force and/or the actual deflection approaches a desired deflection.
When the tensioning element is adjusted relative to the rolling stock section by means of a hydraulic pressure cylinder, a determination of the actual adjusting force and the actual deflection are possible in a particularly simple manner. This is because hydraulic pressure cylinders usually include a position pick-up which is mounted in or on the pressure cylinder, wherein this pick-up is capable of determining the travel distance of the pressure cylinder. The actual adjusting force results directly from the work pressure of the pressure cylinder in connection with the piston cross-section of the pressure cylinder.
The tension control method can be realized in a particularly simple manner if one of the two actual values is kept constant equal to the corresponding desired value and only the other actual value is variable. In this connection, the actual adjusting force or the actual deflection can be kept constant alternatively.
It is particularly simple to keep the actual adjusting force constant if the hydraulic pressure cylinder is subjected to a work pressure from a pressure application device which is subjected to an operational pressure, if the operational pressure includes at least one minimum pressure and if the work pressure is smaller than the minimum pressure.
If the desired adjusting force is selected in such a way that the resulting desired deflection differs from zero, it is possible to detect and correct by means of the tensioning element upward deviations of the tension prevailing in the rolling stock section as well as downward deviations of the tension prevailing in the rolling stock section.
The tension control method can become a self-learning method if the following features are met:
the rolling stock includes a rolling stock end;
a holding element is arranged in front of the front roll stand;
a continuous moment applied by the rear roll stand is determined after the rolling stock end has left the holding element and before the rolling stock end leaves the front roll stand;
a free moment applied by the rear roll stand is determined after the rolling stock end has left the front roll stand and before the rolling stock end leaves the rear roll stand;
the tension actually prevailing in the rolling stock section before the rolling stock end leaves the front roll stand is determined from a comparison of the free moment and the continuous moment; and
correction values for the desired adjusting force and/or the desired deflection are determined from the actually prevailing tension.
When the free moment and the continuous moment are each determined several times and mean values of the free moment and the continuous moment are formed for comparing the free moment and the continuous moment, the influence of problems during rolling will be low.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.
REFERENCES:
patent: 2569264 (1951-09-01), Stone et al.
patent: 3961510 (1976-06-01), Kovacs
patent: 4674310 (1987-06-01), Ginzburg
patent: 5546779 (1996-08-01), Ginzburg
patent: 5701774 (1997-12-01), Imanari et al.
patent: 5809817 (1998-09-01), Ginzburg
patent: 1427893 (1968-11-01), None
patent: 2816091 (1987-04-01), None
Balve Karl-Heinz
Keller Karl
Palzer Otmar
Polok Miroslav
Kueffner Friedrich
SMS Schloemann--Siemag Aktiengesellschaft
Tolan Ed
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