Method for manufacturing an edge protector and die assemblies therefor

A primary die assembly for pre-forming a piece of planar sheet metal into a preformed work piece having a U-shaped cross section, the preformed work piece being provided with a bent portion extending along a longitudinal direction and a pair of planar portions extending from either side of the bent portion, the bent portion being given with a three dimensional contour that conforms to the leading edge of the blade to be protected, the primary die assembly comprising:

• an upper die holder and a lower die holder disposed opposite to each other and configured to be selectively moved toward and away from each other;
• a punch mounted on the lower die holder and including an upper edge that is configured to form a substantially final configuration of the bent portion of the edge protector;
• a blank holder having an opening to pass the punch therethrough and a clamping surface for clamping blank sheet metal at parts corresponding to free ends of the planar portions of the edge protector;
• at least a pair of lateral die blocks supported by the upper die holder so as to be slidable toward and away from lateral sides of the punch;
• springs resiliently urging the die blocks toward each other;
• and
• actuators for causing movements of the upper die holder and lower die holder relative to each other.

A secondary die assembly for forming an edge protector including a bent portion and a pair of planar portions conforming to a leading edge and a pair of lateral sides of a blade to be protected, respectively, the leading edge being given with a three dimensional contour, from a preformed work piece having a U-shaped cross section, the preformed work piece being provided with a bent portion extending along a longitudinal direction and a pair of planar portions extending from either side of the bent portion, the bent portion being given with a three dimensional contour that conforms to the leading edge of the blade to be protected while the planar portions are yet to be formed into final shapes, the primary die assembly comprising:

• an upper die holder and a lower die holder disposed opposite to each other and configured to be selectively moved toward and away from each other;
• a punch mounted on the lower die holder and including an upper edge portion and a pair of lateral sides conforming to the leading edge and lateral sides of the blade to be protected, respectively;
• at least a pair of lateral die blocks supported by one of the upper die holder and lower die holder and configured to cooperate with the lateral sides of the punch to shape the planar portions of the preformed work piece so as to conform to the lateral sides of the blade to be protected;
• an upper clamp member supported by the upper die holder and including a recess conforming to an outer contour of the bent portion of the preformed work piece and configured to clamp the bent portion of the preformed work piece in cooperation with the upper edge portion of the punch;
• and
• actuators for causing movements of the upper die holder and lower die holder relative to each other, and the lateral die blocks toward and away from the punch.