Injection holding machine clamp mechanism

Claim 1

In a plastic injection molding machine carrying first and second sections of a mold having engaging portions the combination which comprises: a. A base; b. A stationary platen fixed on said base in upstanding relationship, said stationary platen carrying the first section of the mold; c. A clamp housing carried on said base in upstanding relationship and movable on said base toward and away from said stationary platen; d. A movable platen carried on said base in upstanding relationship and disposed between said stationary platen and said clamp housing, said movable platen being selectively movable toward and away from said clamp housing and said stationary platen and said movable platen carrying the second section of the mold for selective engagement with the first section of the mold; e. A plurality of elongated tie bars carried by said clamp housing, said stationary platen and said movable platen, said tie bars engaging said stationary platen to prevent movement of said tie bars through the stationary platen, said tie bars slidingly engaging said movable platen to allow relative longitudinal movement therebetween; f. A plurality of pistons and cylinders carried by said clamp housing with each of said cylinders in fixed relationship thereto, each piston having internal threads engaging corresponding threads on one of said tie bars so that rotating all of said pistons varies the mold height of the injection molding machine and application of hydraulic pressure to all of said pistons in one direction causes clamping of the mold; g. Means for traversing said movable platen with respect to said clamp housing along the upper surface of said base; h. Blocking means for limiting relative movement of said movable platen toward said clamp housing; and i. Drive means for simultaneously rotating each of said pistons equal angular increments to vary the mold height of the injection molding machine.