Thermoplastic container forming and punching process in which film clamp applies low tension to film before stretching plug contacts film then clamp makes further movement as film is stretched

摘要

During tool closure, and before a stretching plug(15) contacts the film(18), the end face(21) of the film clamp(12) makes a first stroke movement onto the film. Clamp movement is controled by force and applies low tensioning force to the film. The stretching plug then moves forwards to stretch the film. During the latter movement the film clamp makes a further forward movement to compensate for film thickness reduction due to stretching and thus forms a container edge(20) of required thickness. During tool closure, and before a stretching plug(15) contacts the film(18), the end face(21) of the film clamp(12) makes a first stroke movement onto the film. Clamp movement is controlled by force and applies low tensioning force to the film. The stretching plug then moves forwards to stretch the film. During the latter movement the film clamp makes a further forward movement to compensate for film thickness reduction due to stretching and thus forms a container edge(20) of required thickness. An independent claim is included for the forming and punching tool whose film clamp has a drive unit(14) with both position and force control.