Production of closed bottom shells

Abstract

Elongated closed bottom shells (cans) are produced in the preferred manner by a double-acting punch body arranged on a horizontal axis and reciprocated between opposed die stations at a substantially constant velocity by a hydraulic force alternately applied to opposite sides of a ram on the punch body; blanks (of cup form) are fed to the die stations at times when the punch body dwells at the end of a stroke. Preferably the applied force is such that punch body attains peak (maximum) velocity before the punch encounters a cup centered at the die station; cup feed, cup positioning, punch body travel and formation of a shell of correct length are monitored (sensed) and in the event a programmed condition of machine function or production criterion is sensed as not satisfied, the machine is stopped. During the return stroke of the punch body, after a shell is formed at one station, fluid under pressure is applied by a unique porting arrangement to a separable part of the punch, which thereby serves as a stripper to hold the completed shell stationary at the die station while the remainder of the punch body is retracted from the shell; concurrently, air under pressure is ported in a unique fashion to break any vacuum inside of the shell. After the shell is stripped, the stripper is retracted at an accelerated rate to re-couple with the punch body as it moves toward the other die station. The main cylinder is so supported that thermal effects will not disturb the alignment of the punch body relative to the dies.