Threaded actuator for positioning structure subjected to intense loads

摘要

A threaded actuator is disclosed for positioning a core in a molding apparatus. The threaded actuator includes a hydraulic cylinder unit having a piston rod connected to the core for positioning thereof. The core is subjected to intense force during the molding process and this force is transmitted onto the piston rod and hydraulic cylinder unit and its support. The hydraulic cylinder has a threaded nose which is secured within a threaded opening in a support. A rotatable threaded connecting member is threaded between the threaded nose and the threaded opening of the support structure. The outer and inner threaded connections of the rotatable threaded connecting member are of different thread configurations to form a differential thread assembly. The configurations may differ either in pitch and/or in the handedness of the threads. The differential threaded assembly provides for relative positioning of the hydraulic cylinder unit and core relative to the mold. A preload system includes a wall on the cylinder and a wall on the rod for preloading of the locked rod and the supporting components. The hydraulic cylinder and the piston rod are formed with stop wall members which provide for controlled extension of the piston rod for preloading of the piston rod and the supporting structure. A locking unit provides for locking of the rod in an extended position.