Boots – shoes – and leggings
Patent
1981-06-04
1983-08-09
Chin, Gary
Boots, shoes, and leggings
364563, 72 8, G06F 1546, B21B 3712
Patent
active
043982549
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
The present invention relates to a method for controlling strip thickness in a strip mill and, particularly, provides a method for controlling strip thickness of a new feed-forward system which is capable of controlling variations in thickness having relatively high frequency components.
2. Background Art
In a strip mill, it is very important to maintain the thickness of the rolled strip to a desired value over its entire length. Heretofore, both in a reversing mill and in a tandem mill, a thickness meter was provided on the exit side of the mill, for detecting the deviation in thickness which was fed back to the mill to correct the screw down position and/or the tension applied to the strip. However, the conventional method for controlling strip thickness utilizing the feed-back system had a disadvantage of a slow response characteristic. In a tandem mill comprising, for example, five stands, it was a common practice to use the method of adjusting the screw down position in the first stand in accordance with the deviation in the strip thickness detected by a thickness meter provided on the exit side of the first stand, in combination with the method of adjusting the tension between the fourth and the fifth stands in accordance with the deviation in the strip thickness detected by a thickness meter provided on the exit side of the fifth stand. In this feed-back system, however, a quick response in control was impossible because of a time lag the detection of the strip thickness by each of the thickness meters provided on the exit sides of the first and the fifth stands.
In order to correct this disadvantage of the feed-back system, a new control method according to a feed-forward system was developed, in which, as described in "Control Engineering March 1955", pp. 42-47, the deviation in the strip thickness detected by the thickness meter provided on the exit side of the first stand was stored and variations in the strip thickness at each stand on the downstream side was predicted by calculation, in accordance with which the tension between the stand on the downstream side was adjusted, to thereby control the strip thickness. In this control method by feed-forward system, although capable of solving the heretofore existed problem of the delay the detection of the deviation in the strip thickness, there was a serious problem that it was almost ineffective for a variation in the strip thickness in which the frequency component was as high as several hertz (Hz) or above, as caused by eccentricity in the roll. This ineffectiveness was due to the fact that a roll drive motor for adjusting the tension between the stands was not capable of satisfactorily following the high frequency variation of several Hz or above. The situation would remain unchanged if adjustment of the rolling position was adopted in place of adjustment of the tension between the stands.
A conventional method for controlling the variations in the strip thickness having such a high frequency component is disclosed in the specification of Japanese patent application No. 129877/76.
This conventional method was applicable to a tandem mill comprising a plurality of stands for rolling a strip, for obtaining variation in the strip thickness between a thickness meter disposed between two adjacent stands and a stand on the downstream side thereof by sequentially storing deviations in the thickness of the passing strip detected by said thickness meter, correcting the amplitude and the phase of the strip thickness variation signal in response to the dynamic characteristic of the electric motor driving the roll of either one of said two stands, and varying the rotational speed of said electric motor in accordance with said correction signal to thereby control the strip thickness. This method, however, did not disclose the control method using a rolling position control apparatus. In performing the feed-forward control, as sampling, using the screw down position control device or the tension adjusting device, the most impor
REFERENCES:
patent: 3592030 (1971-07-01), Smith, Jr.
patent: 3702071 (1972-11-01), Masar
patent: 4220025 (1980-09-01), Baba et al.
patent: 4240147 (1980-12-01), Morooka et al.
patent: 4248072 (1981-02-01), Hasegawa et al.
Kondo Katsuya
Tajima Shigeru
Chin Gary
Sumitomo Metal Industries Ltd.
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