Coating processes – Measuring – testing – or indicating
Reexamination Certificate
1998-07-23
2001-02-27
Pianalto, Bernard (Department: 1762)
Coating processes
Measuring, testing, or indicating
C118S405000, C118S419000, C118S423000, C118S672000, C118S712000, C427S431000, C427S434500, C427S434700, C427S436000, C427S443200, C427S449000, C427S598000
Reexamination Certificate
active
06194022
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a process for stabilizing strip a plant for coating strip material, metal strip is taken through a container holding the molten coating material that has, below the melt surface, a through channel, in which induction currents are induced in the coating material by an electromagnetic travelling wave and, in interaction with the electromagnetic travelling field, generate an electromagnetic force to retain the coating material.
2. Discussion of the Prior Art
A plant of this type is described, for example, in German Patent 43 44 939. In this case, the container that holds the molten coating material has an opening for the strip in the bottom. The opening is sealed by an electromagnetic pump. The pump generates an electromagnetic force equal to or greater than the metallostatic pressure in the opening of the through channel. As a result, the molten material is prevented from running out through the opening.
It has been found that the strip, during continuous coating, is alternately deflected or twisted. A remedy for this is not possible with conventional means, e.g., an increase in bath tension. Further roller guides are not possible in this process area, because the coating has not yet solidified.
SUMMARY OF THE INVENTION
Starting from the described problems and disadvantages of the prior art, the object of the present invention is to find a process and a device for stabilizing strip in a generic plant, with which the strip material, without contact from outside, is brought into a more or less symmetrical position, so that the strip does not come into contact with the walls of the coating channel and sustain damage as a result. The stabilization is to be adaptable to different strip widths, strip thicknesses and material qualities.
To attain this object, it is proposed according to the invention that, in the region of the through channel, a controllable magnetic field superimposed on the modulation of the electromagnetic travelling field be applied. The field strength and/or frequency of the controllable magnetic field are adjustable as a function of the sensor-detected position of the strip in the coating channel.
The adjustable magnetic field allows the strip to be guided in the through channel so that the strip is introduced into the coating material without contacting the walls and without vibrations. Mechanical guides are this not necessary.
In one embodiment of the invention, the magnetic field is controlled as a function of the sensor-detected position of the strip in the coating channel. Depending on the position of the strip, the magnetic field is strengthened or weakened or unilaterally changed so that an appropriate correction of the strip course takes place.
Another embodiment, commonly uses the coils for the travelling field both for the purpose of sealing and for that of strip stabilization. The coil pair or pairs are controlled by means of thyristors, which are modulated to such an extent that a reliable seal is achieved. Depending on the position/asymmetry of the strip detected via sensors, an additional modulation of the coil pair or pairs is carried out for the purpose of attaining symmetry.
A device for stabilizing strip in a generic plant is characterized by multiple individually activatable and deactivatable magnetic coil pairs arranged on both sides of the strip in the region of coating channel, whose field strength and/or frequency are adjustable.
The magnetic coils can be arranged on both sides of the strip between the coils of the electromagnetic travelling field and the opening in the container bottom, for example, and can be dimensioned in keeping with the width of the strip.
Because the magnetic coils can be individually activated and deactivated, a more sensitive influence can be exercised on the magnetic field, and the magnetic field can be adjusted to different strip widths.
Alternatively, at least individual magnetic coils can be movably arranged parallel to the strip surface for the purpose of deliberately influencing certain regions of the strip surface and permitting adjustment to different strip widths.
If multiple magnetic coils are arranged on each side of the strip, the magnetic coils can be activated and deactivated individually, so that adjustment to different strip widths, thicknesses and materials is possible within wide limits.
REFERENCES:
patent: 4344939 C1 (1993-12-01), None
patent: 6136502 (1992-10-01), None
Cohen & Pontani, Lieberman & Pavane
Mannesmann Aktiengesellschaft
Pianalto Bernard
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