Cutting tool insert assembly for shears

A removable cutting tool insert assembly for shears fed with stock, such as bar stock;

• said assembly including upper and lower housings;
• and means mounting said housings on each other for relative closing movement toward and opening movement away from each other in one direction transverse to the stock feed direction;
• said mounting means including resilient means normally biasing said housings into spaced apart relationship;
• wherein the improvement comprises:
• upper and lower knives on said upper and lower housings respectively, with one of said knives being offset downstream from the other of said knives in the stock feed direction and with both of said knives being elongated in another direction transverse to both said one direction and the stock feed direction;
• said means mounting said knives including adjustable means providing for relative movement of said knives not only toward and away from each other in the stock feed direction for adjusting the clearance between said knives, but also along each other in said other direction, for centering said knives;
• said upper and lower knives having lower and upper edge surfaces respectively opposing and proximately spaced from each other in said one direction, with said lower and upper edge surfaces being cut away to provide recessed cutting edge surfaces forming respectively top and bottom initial stock engaging portions opposing and remotely spaced from each other in said one direction;
• a hold down and a work support elongated in said other direction and having lower and upper clamping surfaces respectively;
• and means movably mounting said hold down and work support on said upper and lower housings respectively adjacent said upper and lower knives respectively, with said lower and upper clamping surfaces facing said bottom and top initial stock engaging portions respectively;
• said hold down and work support mounting means including resilient means normally biasing said hold down and work support toward said lower and upper knives respectively, one positioning means locating one of said clamping surfaces closer to the opposite one of said initial stock engaging portions than is the other of said initial stock engaging portions, but not as close to said one intial stock engaging portion as is said edge surface of said knife adjacent said one clamping surface, and another positioning means locating the other of said clamping surfaces no further from said other initial stock engaging portion than is said one initial stock engaging portion, but not as close to said other initial stock engaging portion as is said edge surface of said knife adjacent said other clamping surface;
• whereby upon said closing movement, said one clamping surface resiliently clamps one of the upstream and downstream stock portions against the opposite one of said knives both prior to and during shearing, in order to prevent the one stock portion from kicking, while said other clamping surface resiliently clamps the other of the upstream and downstream stock portions against the opposite other of said knives during shearing, in order to prevent the other stock portion from bending.