摘要:
Measuring basis weight of a moving web in the cross direction scanner of a paper-making machine, an encapsulated nuclear source (33) of Promethium 147 is used because of its wide area of emission. To conserve space it is mounted on a vertical axis and moves in a horizontal plane parallel to the moving web from a stowed position where the source is shielded to an active position where the source emits through an aperture, through the moving web, and to a detector. The x-y array planar type detector uses four detector segments (1,2,3,4) symmetrically arranged around a center and compensates for belt direction misalignment, the belt driving the cross direction scanners, by mathematically manipulating the electrical signals from each detector to eliminate the error term. Also a standardization flag (36) is used.
摘要:
An improved differential coat weight technique employs a novel algorithm for measuring the weight of a coating material that has been deposited onto a sheet of substrate. The invention employs dual x-ray or nuclear gauges such that, even though the downstream sensor is never exposed to uncoated sheet substrate, imparting the downstream sensor with the ability to predict results that it would have yielded when measuring the uncoated sheet substrate, leads to the development of a coat weight calibration protocol from which the basis weight of the coating can be ascertained directly from measurements from the upstream and downstream sensors. No subtraction of results is required. Moreover, the two sensors do not need to be re-calibrated whenever the relative proportions of the coating and base substrate change. The technique is particularly suited for applications where the coating material and substrate are made of substances that have very different atomic numbers.
摘要:
A sensor for monitoring the movement of a rotating shaft (1). Mounted on the shaft (1) is a radiation source (5), the radiation from which passes to an associated radiation detector (3) in series of bursts, one per revolution of the shaft. Radiation enters the detector through a window (4) and acts to imbalance the detector, causing a pulse to appear in the potential of collector electrode (9) as the source (5) passes the window (4) on each revolution.