The invention relates to a method and apparatus for measuring the caliper of paper substantially continuously during papermaking. A sensor (3a, 3b) is arranged above and/or under the paper (2), the sensor (3a, 3b) measuring the caliper of the paper (2) at least on one side of the paper (2) mainly without contacting the surface of the paper (2). At given intervals the sensor (3a, 3b) measuring mainly without contact is brought into momentary contact with the surface of the paper (2).
A method for inductively measuring the position of a metal strip is proposed, in which, at least on one side of the strip, a primary coil fed by AC voltage is arranged on one side of a strip edge and a secondary coil is arranged on the other side of the strip edge, which secondary coil measures the voltage which is induced by the primary coil and results from the coupling effect with the primary coil and the metal strip situated in between, in which, as a result of lateral relative movement between the metal strip and the primary and secondary coils, the measurement gradient that can be obtained as a result is determined and compared with a predetermined optimum measurement gradient, whereupon, in the event of a difference, the measurement gradient that has been ascertained is matched electronically to the predetermined optimum measurement gradient and the adapted values then obtained are used for the current strip movement control. This method can also be used for capacitively measuring the position of a metal strip.
An adapter for a precision inspection instrument used for measurement of rollers or rolls in the paper, steel, film industry, without contacting the rollers or rolls. The adapter employs a high pressure fluid, such as compressed air, which emerges through a plurality of nozzles to form an air cushion for supporting the adapter nears the roller. Additionally, the adapter can be provided with adjustable, specifically defined surfaces having nozzles for forming the air cushion on rollers of various dimensions.
A method for increasing caliper control of a fibrous web as the web is wound onto a roll is provided. The method includes winding the fibrous web containing cellulosic fiber onto the roll to form a wound product and conveying the web through a nip prior to winding the web onto the roll. The nip is configured to apply a pressure to the web to selectively decrease the caliper of the web as the web is wound onto the roll. Also disclosed is a system for controlling the caliper of the fibrous web in which a calender device forms a nip through which the fibrous web is conveyed. The system includes an adjustment device, which is configured to adjust the nip of the calender device to increase pressure on the fibrous web as the diameter of the roll increases thus increasing uniformity of the caliper of the fibrous web.
