CONTINUOUS CONTROL OF CARDING PROCESS

Sliver thickness was controlled by analog computer and 20-inch sample card on the basis of the servo-system and the process characteristics are discussed in previous paper.Conventional method for overcoming the dead time in process characteristics could not be applied because of non-linearities of the dead time. However, the decision of controller parameters was possible on analog computer by cut and try method.Some sets of controller parameters from computer are discussed graphically and experimentally examined on the carding engine by giving a disturbance of 50 per cent of controlled variable (sliver thickness aimed).Results are as follows';When out-put sliver of carding process is controlled by changing of the surface speed of doffer, the process characteristics makes it unable to control the short periodic variation, but long periodic one could be controlled without off-set.Control system with two or more parallel controllers which are switched according to the kinds of disturbance is suitable for controlling roller-carding process, because of non-linearity of dead time. In the controller, P. I. actions are suitable than P. I. D. actions, and when D action is added, the system becomes so oscillatory that it seems unusable on account of the high oscillatory components in sliver itself.There is so good agreement between the controlled variables obtained on the analog computer and the experimental ones (obtained on sliver thickness) that the following approximate equeation is usable in practice: