Strand shaping part and method for starting the same

摘要

A strand shaping part for connecting an extruder ( 1 ) to a granulating system has a number of supply channels ( 8 ) that can be flow-connected to the outlet ( 5 ) of the extruder ( 1 ). These supply channels lead to gear pumps ( 21 ) which have a delivery behaviour that is as constant as possible and with which the flow of melt to channels ( 11 ) can be blocked during start up. A single channel ( 11 ) leads from each gear pump ( 21 ) to a strand die ( 9 ) that can be formed by holes of a perforated plate ( 10 ) which is connected to a perforated plate head ( 7 ). Several gear pumps ( 21 ) are driven by a common shaft ( 24 ). The method for starting a granulating system provided with a strand shaping part of the aforementioned type provides that the extruder ( 1 ) is first started until a sufficient pressure is built up at the inlet ( 27 ) of each gear pump ( 21 ). Once this pressure is reached, each gear pump ( 21 ) is started again. In an underwater granulating system, the granulating blades ( 12 ) are rotationally driven last (FIG. 1 ).