METHOD AND IMPLEMENT FOR OPENING HOLE IN SOFT MATERIAL

摘要

A hole opening implement (5, 50) for opening a hole in a soft material (2), comprising a first cutting part and a second cutting part, wherein, while piercing through the soft material, both cutting parts move forward into the soft material while cutting the soft material, such a state that the second cutting part remains in the soft material just after the first cutting part is passed through the soft material is assured so that cut pieces as bound to the soft material can remain in the soft material after the opening, and the first cutting part is formed at the tip of the hole opening implement and the second cutting part is formed at a position on the rear side of the first cutting part in piercing direction, or the first cutting part may be formed in a sharp section and the second cutting part may be formed in such a shape that the cutting force thereof is lower than that of the first cutting part.