Hollow needle with closed profile - has chamfered end with cutting edge at front and blunt stop edge

摘要

The hollow needle with closed profile forms an opening in a body, its end first coming into contact with the latter being chamfered and having a cutting edge. The furthest-protruding portion of the end has a cutting edge, while the less protruding one has a blunt stop edge. The two portions can be joined by an intermediate one parallel to the axis of the needle.