Coating processes – Measuring – testing – or indicating – Thickness or uniformity of thickness determined
Patent
1999-03-17
2000-09-19
Bareford, Katherine A.
Coating processes
Measuring, testing, or indicating
Thickness or uniformity of thickness determined
427 9, 118712, B05D 314
Patent
active
061208337
DESCRIPTION:
BRIEF SUMMARY
This case is a national stage application of PCT/FR97/01457, filed Aug. 6, 1997.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a method and to a device for continuously measuring the thickness of an insulating coating applied to a moving ferromagnetic substrate, such as a metal strip or roll.
2. Discussion of the Background
The travelling metal strip to be coated is especially a steel strip, which is bare or coated with a paramagnetic metal layer, such as a layer of zinc, tin, aluminium or alloys based on these metals, or else already coated with an insulating layer, such as a paint.
The thickness of the paramagnetic metal layer is generally between 1 and 100 .mu.m.
The rotating metal roll to be coated is, for example, a so-called "transfer" roll for transferring the coating onto any strip travelling over the said roll; the metal roll is, for example, a steel roll, bare or coated with a metal layer, such as a chromium layer; the insulating coating is applied to the roll and then transferred onto the strip (these methods are called forward roll coating or reverse roll coating).
The insulating coating to be applied is, for example, a paint or a polymer.
The insulating coating may be applied in the liquid state, for example by coating with a solution (especially in the case of a paint) or by extrusion (especially in the case of a polymer).
The insulating coating may also be applied in the solid state, for example by powder spraying or by pressing a polymer film onto the substrate.
A plant for continuously coating a strip generally comprises means for applying the coating to the strip, means for making the strip travel continuously from the upstream end to the downstream end of the plant and means for adjusting and/or regulating the thickness applied.
In the case of intermediate application to a transfer roll, the thickness applied to the transfer roll may be adjusted or regulated.
In the case of the application of paints, a coating head is normally used as application means and the plant then also includes means for drying the paint, these being placed downstream of the application means.
The drying means are regarded as means for solidifying the coating.
Thus, in the case of the application of paint to a metal strip, the strip passes through the paint application means, emerging therefrom coated with a layer of wet paint, and then passes through means for drying the applied coating, emerging therefrom coated with a layer of dry paint.
As non-contacting means for measuring the thickness of an insulating coating applied to a conducting substrate, devices which combine two types of sensor, the first sensor for measuring the distance from the device to the interface between the conducting substrate and the insulating coating and the second for measuring the distance from the device to the coated surface facing it, are known.
The thickness of the coating is then deduced from the difference between the datum given by the first sensor and the datum given by the second sensor.
This method and this device are, for example, described in French Patent Application No. 2,707,109, in European Patent Application No. 0,629,450 and in German Patent Application DE 4,007,363.
As an example of the second sensor, an optical distance measurement sensor may be used, for example one which operates by triangulation of beams, such as the one described, for example, in U.S. Pat. No. 5,355,083.
As an example of the second sensor, a capacitive sensor may also be used because the applied coating is insulating and because the substrate is conducting; the capacitive sensor must be calibrated depending on the dielectric constant of the coating at the measurement frequency used; specifically, it must generally be positioned a short distance from the coated substrate (about a few millimeters in order to have an accuracy of about 1 micrometer).
The operation of the capacitive-type sensors is based on the measurement of a capacitance formed between a plane electrode of the sensor and the metal substrate; this
REFERENCES:
patent: 5355083 (1994-10-01), George et al.
patent: 5891509 (1999-04-01), Kawana et al.
Patent Abstracts of Japan, vol. 009, No. 269 (P-400), Oct. 26, 1985, JP 60 115804, Jun. 22, 1985.
Patent Abstracts of Japan, vol. 095,No. 001, Feb. 28, 1995, JP 06 300509, Oct. 28, 1994.
Bonnebat Claude
Branci Samy
Bareford Katherine A.
Sollac
LandOfFree
Method and device for measuring the thickness of an insulating c does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and device for measuring the thickness of an insulating c, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and device for measuring the thickness of an insulating c will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1069842