System for adjusting screw position in injection moulding machine - has adjusting ring screwed round circumference of flange on screw plunger cylinder and locked when in position

摘要

The layout for adjusting the position of the screw in an injection moulding machine has the plasticating screw inside a barrel, and a drive unit to rotate and to move axially the screw; the unit has a plunger in a cylinder and a motor attached to the cylinder. One flange is part of the barrel and another flange is part of the cylinder; the two flanges can be coupled together; a ring to adjust the position concerned is unscrewed in a threaded part on the circumference of both flanges; the adjusting member stands out from both flanges, and when the flanges are fixed together the projecting part meets the other flange. The figure shows the screw drive unit, with a cylinder (33), plunger (35) and barrel (27) with the position adjustment device (32). The cylinder (33) has a stepped opening (36) i.e. with its o.d. reducing in stages from the screw side. The plunger (35) has sections of larger (40b), medium (40a) and smaller (40c) dia. The end of the plunger (35) has a groove (41) at the centre, to couple with the screw, the other end being keyed (42) for connection to the motor. One radially supporting member of phosphor bronze (45) (or a low friction bush) lies between the greater dia. section (40b) and the opening (36c) in the cylinder (33); a second member (46) is between the smaller dia. section (40c) and the smaller opening (36d). The assembly has an oil seal (48) and a stop ring. The two flanges are (65) and (70) with their coupling (72); other features shown include the adjusting ring (71). ADVANTAGE - The design solves the problems of existing designs (e.g. difficulty in obtaining accurate and fixed adjustments, and in reducing the screw drive).