GB951848A - Improvements in or relating to the measurement of consistency - Google Patents

Abstract

951,848. Mixing controlled by viscosity. NATIONAL CLAY PIPE-RESEARCH CORPORATION. March 27, 1962, No; 11713/62. Heading B1C. [Also in Divisions G1 and G3] The consistency of a mouldable material, e.g. clay, plastics, rubber, candy, soap or the like, is measured by sensing the presssure on a feeler extending into the material which is moving at constant linear velocity. The measurement is used to control the admission of additional liquid to maintain the consistency constant. As shown, clay in a pug mill 11 is mixed with water from a main nozzle 13 and a fine, controlled, nozzle 41, the mixture being forced through orifices defined-by sealing dies 22, 23 into a vacuum chamber 19 from whence it is extruded through a die 21 to form bricks, tile or pipe. Secured in the orifices are four transducers 30-33, each comprising a spring- loaded plunger attached to the movable core of a differential transformer, the output of each being connected in bridge fashion across a potentiometer to provide an adjustable null position, Fig. 3 (not shown). The output of each bridge is thus an A.C. voltage of magnitude dependent on consistency, and phase sense according to whether this is above or below a desired level. The four outputs are connected in series to give an averaging effect, and the result amplified in a cascode amplifier 36, Fig. 4 (not shown), and applied to a phase discriminator 37, Fig. 5 (not shown. The output of this operates relays 38, Fig. 6 (not shown), to control a reversible motor 39 connected to a valve 40 in the water supply to the fine nozzle 41. Indicator lamps show when conditions are balanced, when the valve is being opened or closed, and if it reaches the end of its travel, when manual adjustment is made to main nozzle valve 43.