Reducing workpiece thickness

Apparatus for the treatment of a sheet material workpiece to reduce the thickness of a selected region thereof, comprising:

• a band knife (4) having a blade portion (6) extending in a cutting plane (20);
• workpiece feeding means (8,10,12) for supporting a workpiece (14) to be treated, said feed means being arranged to feed said workpiece past the band knife in a workpiece feed direction, said blade portion extending transversely of the workpiece feed direction;
• a plurality of pressure-applying elements (18) extending in at least one row, immediately in advance of the knife and transversely of the workpiece feed direction, each element being independently movable between an extended condition, where it applies pressure to a section of a workpiece region to cause said section to be deformed in relation to the cutting plane and a retracted position where it does not apply such pressure;
• actuator means (16) for effecting movement of each pressure-applying element (18) into and out of its extended condition;
• and,
• control means for controlling the operation of the actuator means whereby combinations of elements can be caused to be successively located in their extended condition in timed relation with the operation of the workpiece feeding means;
• characterised in that the workpiece feeding means (8, 10, 12) comprises a workpiece support (8) configured to yield under pressure applied by the elements (18) to vary the relationship between said workpiece region supported thereby and the cutting plane, and thus the cutting blade portion (6), to be varied.