Punch of punching press, nibbler assembly, and method of forming elongated hole in sheet material

A punch for a punching press capable of performing a nibbling operation on a sheet material while the sheet material is fed in a feed direction, the punch comprising:

• a first blade section and a second blade section juxtaposed relative to each other on a punch lower surface in a direction parallel or substantially parallel to the feed direction of the sheet material;
• an upstream side end surface and a downstream side end surface that each include a plane surface perpendicular to the feed direction;
• and
• a pair of side surfaces that each include a plane surface extending in the feed direction and the vertical direction;
• wherein
• a recess is defined between the first blade section and the second blade section at the punch lower surface, the first blade section being located on a downstream side of the recess with respect to the feed direction and the second blade section being located on an upstream side of the recess with respect to the feed direction;
• the first blade section extends downwardly of the second blade section, and includes a first bottom surface including a downstream end edge, an upstream end edge, and a pair of first side edges;
• the first bottom surface has a protruding shape which extends at an incline downwardly from the upstream end edge in the feed direction to a lowest end of the punch, and further extends such that the protruding shape is inclined upwardly from the lowest end to the downstream end edge in the feed direction;
• the upstream end edge and the downstream end edge define a punching edge, and the pair of first side edges define a notching and punching edge;
• the second blade section includes a second bottom surface including an upstream end edge, a downstream end edge, and a pair of second side edges;
• the second bottom surface has an inclined shape which extends at an incline downwardly from the upstream end edge to the downstream end edge in the feed direction;
• and
• the upstream end edge defines a punching edge, and the pair of second side edges defines a notching and punching edge.