Study on A New Method of On-line and Precise Measurement of Disc Refiner's Refining Gap

Based on the need for precise, fiber-scale and on-line measure of disc refiner's refining gap (DRRG) in papermaking industry, the characteristics of structure and refining gap of disc refiner were firstly discussed; and a new method with Eddy Current Sensor(ECS), of on-line, precise and direct measurement of DRRG was studied systematically and for the first time, including ECS's fixing edge and indent effect,ECS's Response Characteristics(RC) and the optimized linearity characteristic regression equation, the measuring principle and DRRG data process, as well as the display instrument's scale transformation. The followings were indicated: ECS's fixing edge is no less than 3mm; the ECS with diameter of 11mm, sensitivity of 2 V/mm and linearity of 5mm is fit to DRRG measurement for the refining disc with, as a rule, tooth height of 2~7mm, tooth width of 2.4~4.5mm and groove width of 1.5~4.0 mm; ECS's RC recurs very well while rotating disc advances and retreats; ECS's RC is not relative to the kind, consistence, and flux of pulp, which makes for measurement dependability.