Patent ID: 6821463
Filing Date: 2004-11-23
Classification: B29C

Abstract:
Method for clamping molds in an injection molding press of the type comprising:a first platen for supporting a first half mold; a second platen for supporting a second half mold, at least one of said platens being slidably movable with respect to the other one, parallel to a longitudinal axis of the press; a plurality of peripheral tie-rods parallely extending to said longitudinal axis between the two mold supporting platens of the press; first control means being provided for moving one platen towards and away from the other one, upon the closure and opening of the mold; and second control means for the tie-rods, and threaded bush members parallely arranged to the longitudinal axis of the press, said bush members having a threaded portion operatively connectable to a threaded portion of said tie-rods, to provide a high clamping force to tightly close the mold, the method comprising the steps of: supporting the tie-rods axially sliding with respect to both the platens of the press; providing a locking bush, for each tie-rod, rotatably and movably supported in the axial direction, by one of the platens of the press; each locking bush and the corresponding tie-rod including opposite interengaging screw threaded portions having an axial clearance between them; moving one of the platens in respect to the other one for closing and respectively for opening the mold by actuation of said first control means maintaining the screw threaded portions of the locking bushes and the tie-rods frictionless disengaged by synchronously rotating the locking bushes; interengaging the screw threaded portion of the tie-rods with the screw threaded portion of the locking bushes by causing an axial sliding movement of the bushes by said second control means, to urge a shoulder member of the bushes against a corresponding shoulder surface of the platen of the press; and subsequently providing a clamping force to tightly close the mold, by generating a high axial force on the tie-rods and the locking bushes.