Design and application of rod hardness tester unit in test station

To improve the accuracy and stability in hardness testing of cigarette and filter rod, a novel hardness tester unit in test station was designed. The unit was mainly composed of a test platform, air cushion shaft, a mechanism for rod sample rotation, weights and sensors. The pressure was vertically loaded and the whole loading process was controlled by an air flotation device, and the rod hardness was measured by a laser meter displacement. A step motor was used in order to control loading speed accurately. The hardness of five standard articles and fifteen cigarette samples of different brands was measured by the novel test station and compared with two test stations in which the pressure was loaded horizontally. The results showed that:1) Both pre-pressure and full pressure of the novel unit met standard's requirements. 2) The RSDs of hardness of the five standard articles were 0.005%-0.015% and 0.020%-0.035%, the measurement accuracies were 0.001-0.009 mm and 0.003-0.009 mm by vertical loading unit and horizontal loading unit, respectively; it indicated that vertical loading was superior to horizontal loading obviously. 3) The RSDs of hardness of the fifteen cigarette brands ranged from 3.25% to 5.85%, the results showed good stability and consistency. 4) The RSDs of novel and two other test stations were 2.93%-3.06%, 3.94%-4.33% and 3.70%-4.18%, respectively; novel test station was superior to the two horizontal loading testers. The improved rod hardness tester unit satisfies the requirements of industrial standard.