Pull-back ram cylinder apparatus

摘要

A pull-back ram cylinder apparatus in combination with a vertical mold clamping machine to be incorporated in a vertical molding or casting machine. The pull-back apparatus comprises a hydraulic cylinder for actuating a hollow ram. A ram extension consisting of the ram and a ram rod extending into the ram in a thread engagement is slidably fitted in the cylinder. The ram rod extends downwardly from the cylinder and is connected to a movable platen of the clamping machine carrying a movable mold. The cylinder has a lower throttle portion in which radial openings for discharging an operation oil are formed in an axially spaced arrangement. The inner diameter of the throttle portion is slightly larger than the outer diameter of the ram. The throttle portion having the axially spaced openings serves, in cooperation with the head end portion of the ram, as buffering means by which the movable mold is allowed to come into contact gently with a stationary mold. The thread engagement of the ram and the ram rod is advantageous in that the positional relationship between the movable platen and the ram can be easily adjusted according to the change of the thickness in molds.