Procedure and device to determine the thickness of a coating applied to a web by a machine.

p0001The invention relates to a method for determining the thickness of the, applied by a coating device on a path which passes between an applicator roll and a backing roll of the coating device consisting of glue or other coating material coating.

p0002In the coating of webs is the particular problem to measure the thickness of the existing from the applied coating layer in order to adjust the coating apparatus by corresponding control or regulation to the desired layer thickness can.

p0003For thickness control, it is known, or the like a scraper to the coated web. to make and to scratch with this, the coated layer or scrape to control in this way, the thickness of the applied layer. Such visual inspection is very inaccurate and therefore unsatisfactory.

p0004Furthermore, it is known to cut a test piece of the coated web and subtracted from this, the applied coating so that the sample with and without coating and weighed from the weighing operations, the applied weight per unit area of ​​the coating can be determined. This type of determination of the layer thickness or the basis weight of the coating is extremely complicated and does not allow for rapid regulation of the layer thickness during the coating of the web with a coating machine.

p0005The object of the invention is therefore to provide a method of the type mentioned after can be the thickness or weight per unit area of ​​the applied coating to the web constantly determine quickly and accurately.

p0006This object is achieved in a method of the generic kind in that the film thickness of the applied coating composition on the applicator roll was measured before and after the contact area of ​​the applicator roll to the web to be coated, and the difference between the measured film thicknesses, the thickness of the web removed coating is determined. The film thickness on the application roller can be determined in a simple manner with known sensors and associated signal processing electronics, so that by the inventive process constantly the actual thickness or the actual weight per unit area of ​​the coating is measured and, if necessary, the coating machine to the desired setpoint can be set or adjusted coating thickness. The inventive method can be carried out in a particularly simple manner, because the film thickness measurements are made not on the coated web itself, but on the application roller.

p0007An apparatus for carrying out the method according to the invention is characterized according to the invention is characterized in that are directed to the application roller on both sides of the contact portion of the supported from the back press roller train Schichtdickenmeßköpfe that generate the measured layer thicknesses corresponding signals. The measurement heads or sensors to the ultrasonic or light reflection principle. Appropriately, the application roller made of steel and is provided with a sheath of a ceramic coating. Such a jacket reflected light to measure coating thickness used especially well.

p0008Preferably, the measuring heads each have an emitter and a detector that receives the reflected pulses of energy.

p0009As sensors under the name MICRO-QUAD 8000 by the company Moisture Systems Corp. in Hopkinton, Mass. USA sold, are used by the infrared backscatter principle working measuring systems, according to which a light beam is optically split, bundled and guided to the object. With infrared optical filters, a measuring and a reference wavelength is generated, and only the measuring pulse is absorbed. The reflected energy from the object is brought to a detector via a concave mirror, and through electronic circuits a dependent on the layer thickness electrical signal is generated which is then fed to the further evaluation.

p0010An embodiment of the invention will be described in greater detail using the drawing, in the single figure of a coating machine is shown schematically with Schichtdickenmeßvorrichtung.

p0011The coating machine essentially consists of an application roller 6, to which a counter pressure roller 2 is employed, which is partially looped around by the web to be coated first The platen roller is supported by a Stützpresseur third Furthermore, rollers 4, 5 are mounted in the machine frame, not shown, are used to guide the web. 1

p0012On the supported by the platen 2 web 1 is a coating composition, for example glue, applied by the application roller. 6

p0013The applicator roller 6 receives its order of coating of a metering roll 7, which forms a trough-shaped receiving gap for the coating 9 with a Vordosierwalze. 8 The amount of funds transferred by the metering roller 7 to the application roller 6 coating composition can be adjusted by a corresponding speed difference between the metering roll 7 and the Vordosierwalze. 8 The Beschichtunsgmaschine is of known type and is therefore not described in detail here.

p0014The passing therethrough through the gap between the applicator roller 6 and the pressure roller 2 web 1 takes the form roller 6, the coating composition, for example glue, for the most part from.

p0015Before and behind the contact area of ​​the applicator roll to the web to be coated 1 are perpendicular to the applicator roller 6, the measuring heads 10, 11 a Schichtdickenmeßeinrichtung addressed, so that the thickness of the on-form roller 6 film of the coating composition before and after the loss of a portion of this coating composition is measured by the web first The measured values ​​are an electronic differentiator supplied 12, the result of this difference, which is a measure of the coating thickness, can be read on the display. 13