Apparatus and method for injection molding

A method for operating a clamp unit of an injection molding machine, the clamp unit comprising:

• a fixed platen for supporting mold members;
• a movable platen assembly for supporting mating mold members;
• a plurality of strain rods spanning from the fixed platen through the moveable platen assembly, the movable platen assembly comprising a mold supporting platen for supporting mating mold members, a clamp force actuator, and a plurality of split locking nuts each split locking nut comprising opposed movable nut halves for releaseably engaging the strain rods, the number of split locking nuts being no less than the number of strain rods, the method comprising the steps of:
• a) simultaneously moving the movable nut halves to disengage the split locking nuts from the strain rods by a strain rod locking mechanism connected with all split locking nuts;
• b) positioning the movable platen assembly so as to abut the mold members and mating mold members;
• c) simultaneously moving the movable nut halves to engage the split locking nuts with the strain rods by a strain rod locking mechanism connected with all split locking nuts wherein:
• (i) the split locking nut halves are pivotably supported by the movable platen assembly and are engaged with and disengaged from the strain rods by applying a force to each nut half at a point proximate the end of each nut half opposite the end at which the nut half pivot axis is located so as to pivot the nut half about the nut half pivot axis;
• and,
• (i)(ii) applying a force to each pivotable nut half comprises coupling rotation of a rotating member through a predetermined angular range to each pivotable nut half by a translating member;
• and
• d) operating the clamp force actuator to apply clamp force to the abutted mold assemblies sufficient for injection and curing of melt.