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
2002-02-11
2003-08-05
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
C072S008900, C072S011600, C700S150000
Reexamination Certificate
active
06601422
ABSTRACT:
FIELD OF THE INVENTION
Our present invention relates to a method of operating a rolling train, especially for the production of structural shapes. The invention also relates to a rolling method, to a control system for a rolling line or train and to a rolling train provided with that control system. Specifically the invention deals with the rolling in a succession of mill stands, of an elongated workpiece to produce a structural shape, also referred to as a profiled product.
BACKGROUND OF THE INVENTION
In the production of structural shapes, rolling mill stands may be grouped together or arrayed in a rolling train and the elongated workpiece is passed in succession through these mill stands to reduce the cross section of the workpiece from stand to stand and thereby impart a particular configuration or profile to that workpiece in producing the rolled product. The rolled product may be composed of steel and the number of roll stands and the configurations of the rolls therein may vary depending upon the product produced and the size of the product.
Each roll stand is operated with a number of operating parameters which can include temperatures, speeds, rolling forces and, of course, such parameters as gap width and roll position, all of which or some of which may be controlled by effectors, for example, servomotors which may be fluid-operated or servovalves. The operating parameters can be adjusted in accordance with a setpoint value and it is known to provide the rolling stands with controls for supplying the setpoint values for a variety of such operating parameters.
The generally elongated workpiece is passed through the succession of mill stands in a rolling direction and a number of mill stands thus are disposed in succession in this direction so that the rolls of this mill stand can engage the workpiece in succession or one after the other and either at the same time or after the workpiece has left a preceding mill stand and entered a succeeding mill stand. The workpieces can be shaped in a single pass through the rolling mill train or in multiple passes.
A rolling train having a multiplicity of such stands is commonly used for the shaping of profiled rolled products or structural shapes and the profiled rolled product can be a so-called “heavy profile” with a U cross section or a double-T cross section or I-beam or H-beam cross sections. These cross sections have a web, usually the base of the channel for U-shaped cross sections and the central member of the H-beam or I-beam, and flanges which extend perpendicularly to one or both sides of the web.
In the shaping of such profiled workpieces in rolling mills, so-called universal mills are used at least in part. A universal mill comprises generally two horizontal rolls which are paired to roll the web of the structural shape and have a gap between them which is adjustable and determines the web thickness and a pair of vertical rolls which engage the opposite sides of the workpiece and determine the overall width of the structural shape produced.
These vertical rolls are usually disposed within the universal stand and can be located somewhat offset from the pairs of horizontal rolls.
In the operation of rolling lines with such mill stands, especially universal mills, each mill stand is supplied with setpoint values for a number of its operating parameters which are selected so that the product, upon rolling in that mill, will approach the setpoint profile of the desired product as closely as possible. These setpoint values adjust the mill, therefore, for the web thickness, the flange thickness, the rolled product width and like dimensions of the finished product. The setpoint values may be, for example, hydraulic pressures for the hydraulic controllers of roll positions or for the desired rolling forces.
In modern rolling trains, it is not uncommon to utilize derivative and comparatively complex operating parameters rather than simple parameters like roll positions, these more complex parameters taking into consideration factors such as temperature, gap cross sections and the like.
In any case it is important that the setpoint parameters which are applied to a particular mill stand be capable of producing a rolled product which is comparatively close in profile to the desired shape with dimensions within a limited tolerance range. However it is difficult to maintain comparatively narrow tolerances since during the rolling operation itself, various influences on such parameters arise and change in a relatively uncontrollable manner. As a consequence it is necessary to carefully monitor the rolling process and most commonly the operators are required to vary practically continuously the operating parameters applied to the mills during the rolling of a given workpiece or a series of such workpieces or even from workpiece to workpiece. In spite of these efforts, however, a high degree of precision and practically narrow tolerances cannot be satisfactorily maintained or can only be maintained with considerable expenditure of effort or with especially extensive equipment.
OBJECTS OF THE INVENTION
It is, therefore, the principal object of the present invention to provide an improved method of operating a rolling train of the above-described type and particularly for the production of structural shapes and especially heavy structural shapes such as channel, double-T girders, H-beams and I-beams, whereby drawbacks of earlier systems are avoided.
It is a particular object of the invention to provide a method of controlling a rolling train for such purposes whereby a comparatively low capital and operating cost, it is possible to obtain especially narrow tolerances in the production of profiled rolled products, i.e. structural shapes.
Another object is to provide a control system for a rolling mill train which allows narrow tolerances which establish and hold more reliably than with earlier systems.
A further object of this invention is to provide a rolling mill train for the rolling of structural shapes whereby drawbacks of earlier systems are avoided.
SUMMARY OF THE INVENTION
These objects and others which will become apparent hereinafter are attained, in accordance with the invention, in a method of operating a rolling mill train for producing structural shapes, especially heavy structural shapes or profiled products which comprises the steps of:
(a) rolling a workpiece in a succession of mill stands, each equipped with a plurality of working rolls engaging the workpiece to reduce a cross section thereof in a configuration of a structural shape to be produced, each of the mill stands having a plurality of adjustable operating parameters determining the rolling process in the respective mill stand;
(b) detecting a profile of a structural shape produced by the succession of mill stands and comparing the detected profile with a set-point profile corresponding to a structural shape to be produced;
(c) deriving from the comparison of the detected profile with the setpoint profile respective corrective setpoint values for each of the parameters determined by deviation of the detected profile from the setpoint profile;
(d) weighting each of the corrective setpoint values with a weighting factor specific to the respective mill stand to produce weighted corrected setpoint values for each of the parameters; and
(e) adjusting the operating parameters of each of the mill stands with the respective weighted corrected setpoint values.
According to the invention the corrected setpoint values for at least one of the mill stands include a setpoint value for at least one structural shape dimensional parameters selected from a web thickness, a flange height and a flange thickness.
The corrected setpoint values can include setpoint values for each of the key structural shaped dimensional parameters, namely, flange height, flange thickness and web thickness.
According to another feature of the invention each of the mill stands is controlled individually by respective determinations of deviations of detected profiles from setpoint profiles for the res
Breunung Detlef
Hartmann Ralf
Palzer Otmar
Reismann Hans-Jürgen
Dubno Herbert
SMS Demag Aktiengesellschaft
Tolan Ed
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