Metal deforming – With use of control means energized in response to activator... – Metal deforming by use of roller or roller-like tool element
Patent
1991-12-03
1993-09-07
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
72 10, 364472, B21B 3712, G06F 1500
Patent
active
052418472
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a rolling control method and apparatus for a tandem mill for hot-rolling a roll material such as steel and non-ferrous metal material, and which is capable of obtaining a good strip profile.
PRIOR ART
A tandem mill for hot-rolling a strip is called a hot strip mill (HSM). In HSM, prior to hot-rolling a strip, initial settings are made at each stand, such as setting a gap, roll speed, and the like. At these initial settings, it is also necessary to set the initial delivery thickness of a strip at each stand. Setting the initial delivery thickness of a strip at each stand includes a work of distributing delivery thickness at respective stands (path schedule). This path schedule influences not only the production efficiency of rolled products at the hot-rolling process, but also the production quality such as the strip profile (represented by a difference between the thickness at the central portion in the widthwise direction and the thickness at an edge portion, and crown ratio) of a strip, surface characteristics, strip thickness precision, and the like. Determining the path schedule is therefore a very important task.
With a conventional method of determining a path schedule, the delivery thickness of a strip at each stand has been determined in accordance with a rolling power curve empirically obtained. Instead of such a conventional method, a new method has been proposed and is now being used. With this new method, an optimum path schedule is determined by directly considering parameters other than the power distribution of driving motors at respective stands, the parameters including the flatness of a strip, the strip profile, and the like. This method is now mainly used in this field. Various methods of this type have been proposed as disclosed, for example, in Japanese Patent Laid-open Publications Nos. 54-139862, 55-64910, 57-209707, and 59-73108.
The method disclosed in Japanese Patent Laid-open Publication No. 54-139862, determines a path schedule in accordance with a target flatness, target strip thickness, and target strip crown, with respect to a material flatness at each path. The method disclosed in Japanese Patent Laid-open Publication No. 55-64910 determines a path schedule through learning in accordance with a target flatness, target strip thickness, and a target strip crown at each path. The method disclosed in Japanese Patent Laid-open Publication No. 57-209707 reflects reduction distribution data for respective stands obtained from the past rolling data, to a new lot. The method disclosed in Japanese Patent Laid-open Publication No. 59-73108 determines an optimum path schedule in accordance with the target values of the strip crown and strip configuration at the last stand of HSM, by using an iterative calculation method for model equations of a mechanical crown and load.
The above-described various proposed methods are associated with a problem that they cannot change rolling force for each stand which directly influences various qualities including the strip profile and configuration of a rolled product. The reason why this problem occurs will be described below.
The load pattern is represented by a ratio .gamma..sub.i of a load P.sub.i at each stand to the maximum load P.sub.MAX.
The load ratio .gamma..sub.i is defined by 0 <.gamma..sub.i .ltoreq.1, and at least one stand takes a ratio .gamma..sub.i =1. In an actual hot-rolling operation, however, the load pattern is changed, in many cases, due to complicated factors such as the roll abrasion state at each stand, a method of burning a slab at a reheating furnace, and a path schedule at a roughing mill and the like. An operator changes the load pattern of a generally theoretically or analytically obtained standard optimum path, while considering an actual rolling condition. In a system wherein a path schedule of HSM is determined and a delivery thickness and the like of a strip are calculated and set in accordance with the path schedule, it is necessary to automatically set
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patent: 4633692 (1987-06-01), Watanabe
patent: 4736305 (1988-04-01), Watanabe
Y. Kotera and F. Watanabe, "Shape Control Method for Continuous Strip Mills", Iron and Steel Engineer, May 1987, pp. 13-17.
Miyashita Makoto
Tsugeno Masashi
Kabushiki Kaisha Toshiba
Larson Lowell A.
Schoeffler Thomas C.
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