Apparatus for the cold deep drawing of films

An apparatus for forming one or more depressions in a thermoplastic film, comprising:

• a) one or more guide columns;
• b) a mold, having a generally planar surface upon which the thermoplastic film is placed, one or more generally cylindrical bores which extend perpendicularly from the planar surface into the mold, with each bore having an opening at the planar surface, and further having axial bearings through which the guide columns pass, the mold being movable along the guide columns in first and second directions which are perpendicular to the planar surface;
• c) a holder for releasably clamping the thermoplastic film to be worked upon against the planar surface of the mold and restraining it from movement, the holder having bearings through which the guide columns pass and being movable along the guide columns in the first and second directions which are perpendicular to the planar surface;
• d) resilient means for urging the holder into clamping relationship with the mold when the mold is moved in the first direction;
• e) first and second bearing plates;
• f) one or more dies, each mounted on a pinion shaft which is rotatably retained between the first and second bearing plates, whereby each die is rotatable about an axis which is perpendicular to the planar surface of the mold, and wherein each die corresponds to a bore in the mold and is of proper size to fit into the corresponding bore in the mold;
• g) a drive pinion for rotationally driving the pinion shafts;
• h) a motor for rotationally driving the drive pinion;
• and,
• i) means for moving the mold in the first and second directions, whereby movement of the mold in the first direction initially causes the holder to be urged into clamping relationship with the mold, thereby clamping the thermoplastic film against the planar surface of the mold, whereby further such movement next brings the dies into contact with areas of the thermoplastic film which is clamped against the planar surface, whereupon rotation of the dies frictionally heats the areas of the film so contacted and softens them, and whereby further such movement then causes the dies to urge these softened areas of the film into the corresponding bores in the mold, thereby forming the desired depressions in the film, and whereby movement of the mold in the second direction first removes the dies from contact with the thermoplastic sheet and next removes the holder from clamping relationship with the mold, thereby releasing the thermoplastic film from the apparatus.