Patent ID: 6171531
Filing Date: 2001-01-09
Classification: B29C

Abstract:
In an extrusion blow molding machine having a master accumulator and a slave accumulator supplied by at least one extruder, each accumulator having a ram that is moveable to change an internal volume of the accumulator, a method for controlling simultaneously the rate at which the volume of each accumulator changes, comprising the steps of:a) selecting an operating parameter that relates to movement of the ram in each accumulator,b) establishing a reference set point for the operating parameter of the master accumulator,c) establishing an initial set point for the operating parameter of the slave accumulator,d) initiating simultaneous movement of the ram in each accumulator,e) providing closed loop control of the operating parameter for each accumulator according to the respective set point,f) determining the position of the ram of each accumulator,g) comparing the position of the rams as a percentage of the full stroke of each accumulator, andh) adjusting the set point of the slave accumulator on the basis of the position comparison of step (g) to alter the rate of movement of the ram in the slave accumulator so that the rams of the accumulators will reach a full stroke at essentially the same point in time.