Vacuum holder for sheet materials

摘要

A sheet material holder includes a vacuum platen defining a plurality of arrays of vacuum channels corresponding in number and size to a plurality of sheet material sizes on one surface thereof and including a corresponding plurality of distinct vacuum plenums communicating with the arrays of vacuum channels; a vacuum pump; a corresponding plurality of remotely actuatable valves connected between the vacuum plenums and the vacuum pump; a corresponding plurality of flow sensors for sensing the flow of air between the plenums and the vacuum pump; and logic and control means connected to the flow sensors and the valves for sensing air flow between a plenum and the vacuum pump and actuating the corresponding valve. Sheet size is automatically inferred by the pattern of valves that are actuated.