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
2000-03-23
2001-09-11
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
C072S010300, C072S011500, C072S011800
Reexamination Certificate
active
06286348
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a strip thickness controller for a rolling mill, for controlling delivery thickness of the strip in the rolling mill.
BACKGROUND OF THE INVENTION
There are a variety of rolling mills for rolling a steel plate etc., of which categories differ depending on the number of rolling rolls per stand. What the present invention is applied to, is a rolling mill including at least a pair of backup rolls disposed up and down. The following discussion will concentrate on a four-high rolling mills including a pair of work rolls and a pair of backup rolls.
A roll eccentricity of the rolling mill may be a large disturbance to control of a thickness of the strip or to tension control. Principal factors for causing the roll eccentricity are:
(a) an influence of a bearing key of the backup roll,
(b) a bias of an axial core of the backup roll, and
(c) ill-formed roundness of the work roll.
The eccentricity caused by the factor (a) among these factors, it is conceived, has the largest eccentric quantity.
A variety of methods of reducing the roll eccentricity in a control-based manner have been proposed and applied to a multiplicity of rolling plants. A typical method thereof is disclosed in JP 51-138468 A. According to this method, a rolling force signal detected corresponding to a rotational angle of the backup roll is Fourier-transformed, then a frequency component synchronizing with the rotation of the backup roll is extracted, and a roll gap is controlled by use of this frequency component.
Based on this prior art method, a rolling force generated by rotating and making the up-an-down rolls contact with each other in a non-rolling state, i.e., by performing a so-called kiss-roll, is detected and Fourier-transformed, thereby detecting a roll eccentricity. This method may be said to have a high detection accuracy because of only the roll eccentricity appearing in a rolling force signal generated. With a progress of rolling process, however, a state of the rolls might change, and hence a requirement for adopting this method is that the kiss-roll can be easily done in order to respond to that change. This method is therefore hard to be applied to a tandem rolling mill incapable of easily performing the kiss-roll, and it is, if applied, difficult to attain high-accuracy control.
SUMMARY OF THE INVENTION
Accordingly, it is a primary object of the present invention to provide a strip thickness controller for a rolling mill, which is capable of reducing a delivery-side strip thickness deviation due to an eccentricity of a backup roll even in a rolling mill incapable of easily performing a kiss-roll.
To accomplish the above object, according to a first aspect of the present invention, a strip thickness controller for a rolling mill comprises a thickness gauge, provided in a position spaced a distance shorter than a circumference of each of backup rolls of the rolling mill on a delivery side of the rolling mill having work rolls and the backup rolls, for detecting a strip thickness deviation from a strip thickness set value, a rotational angle detecting unit for outputting a rotational angle detection signal at every equally-segmented portion when an angle of one rotation of the backup roll is, with “n” being a positive integer, segmented equally by “n”, a strip length calculating unit for calculating a forward slip of the length calculating unit for calculating a forward slip of the rolling mill at a point of time when a first rotational angle detection signal is outputted from the rotational angle detecting unit, and calculating, based on the forward slip and the circumference of the backup roll or a value relative thereto, a delivery-side strip length of the rolling mill which corresponds to one rotation of the backup roll, a strip thickness deviation delaying unit for delaying a strip thickness deviation signal of the thickness gauge by a strip transfer time corresponding to a difference between the delivery-side strip length calculated by the strip length calculating unit and a distance of the thickness gauge from the rolling mill, a roll gap control quantity calculating unit for integrating the strip thickness deviation signal delayed by the strip thickness deviation delaying unit at the every same rotational angle of the backup roll which is detected by the rotational angle detecting unit, and calculating each roll gap control quantity of the rolling mill, corresponding to the rotational angle of the backup roll, and a roll gap controller for controlling a roll gap of the rolling mill in accordance with the roll gap control quantity calculated by the roll gap control quantity calculating unit.
According to this strip thickness controller, the strip thickness deviation signal of the thickness gauge is delayed by the strip transfer time corresponding to the difference between the rolling mill delivery-side strip length corresponding to one rotation of the backup roll and the distance of the thickness gauge from the rolling mill. This delayed strip thickness deviation signal is integrated at the every same rotational angle of the backup roll, and the roll gap control quantity of the rolling mill is calculated corresponding to each rotational angle. Hence, even in the rolling mill incapable of performing a kiss-roll, the delivery-side strip thickness deviation due to the eccentricity of the backup roll can be decreased.
A strip thickness controller for a rolling mill according to the present invention comprises a thickness gauge, provided in a position spaced a distance shorter than a circumference of each of backup rolls of the rolling mill on a delivery side of the rolling mill having work rolls and the backup rolls, for detecting a strip thickness deviation from a strip thickness set value, a rotational angle detecting unit for outputting a rotational angle detection signal at every equally-segmented portion when an angle of one rotation of the backup roll is, with “n” being a positive integer, segmented equally by “n”, a work roll speed detecting unit for detecting a speed of the work roll of the rolling mill, a strip length calculating/storing unit for calculating, with “j” being an arbitrary integer equal to or smaller than “n”, a forward slip of the rolling mill at a point of time when a j-th rotational angle detection signal of the backup roll is outputted from the rotational angle detecting unit, calculating a delivery-side strip speed of the rolling mill on the basis of this forward slip and a speed of the work roll, calculating a j-th delivery-side strip length in the rolling mill on the basis of the strip speed and an elapse time from a (J-1)th rotational angle through the j-th rotational angle of the backup roll, and sequentially storing the delivery-side strip length, a thickness gauge arrival strip detecting unit for integrating the delivery-side strip lengths tracing back to the past form the j-th strip length which are stored in the strip length calculating unit, and detecting such a rotational angle number of the backup roll that the integrated value corresponds to a distance between the rolling mill and the thickness gauge, a strip thickness deviation storing unit, having n-pieces storage areas, for sequentially storing the strip thickness deviation detected by the thickness gauge in the storage area corresponding to the rotational angle of the backup roll, and outputting the previous strip thickness deviation in the storage area which is stored with a delay corresponding to the rotational angle number detected by the thickness gauge arrival strip detecting unit as viewed from the present storage area, a roll gap control quantity calculating unit for integrating the strip thickness deviation signal delayed by the strip thickness deviation delaying unit at the every same rotational angle of the backup roll which is detected by the rotational angle detecting unit, and calculating each roll gap control quantity of the rolling mill, corresponding to the rotational angle of the backup roll, and a roll gap controller for controllin
Chujo Takashi
Sekiguchi Kunio
Tonami Yosuke
Foley & Lardner
Kabushiki Kaisha Toshiba
Tolan Ed
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