| 摘要 |
A knife includes first and second edges, a ridge, a concave surface, and a planar surface. The edges are defined by intersections of outer edge forming surfaces on an outer side of the knife and inner edge forming surfaces on an inner side of the knife. The ridge is on the inner side and the crest of the ridge is parallel to the first and second edges. The concave surface is between an inner edge forming surface and the ridge, and the planar surface is adjacent to the concave surface and between that first inner edge forming surface and the concave surface. A reference plane intersects the first and second edges, and a distance between any point on the concave surface and the reference plane is not less than a distance between any point on the planar surface and the reference plane. |
