METHOD FOR MAKING HOLE WITH LARGE DIAMETER, AND APPARATUS FOR MAKING HOLE WITH LARGE DIAMETER

摘要

PURPOSE: To make a hole with a large diameter in a relatively heavy material to be perforated without generating vibration by a method wherein a hole-saw is moved into a deep part of the material while it is rotated and the core part of a cut part of the cut matericl to be perforated is pulled out from the rear end opening part of the hole-saw. CONSTITUTION: A hole-saw 10 is rotated by actuating a driving motor 42. Then, the hole-saw 10 is gradually advanced toward a material to be perforated by actuating a hydraulic cylinder for transferring a table. When the perforating work is advanced, the material is perforated by means of the hole-saw 10 and a core A prepd. by cutting the material is separated from other parts in the deepmost part of the material in the follow part of a cylindrical body 12 of the hole-saw 10 and only the core A is left in the hole-saw 10. In this state, rotation of the hole-saw is stopped and a wire is hanged on an anchor bolt 112 which has been driven in advance into the outer surface of the core A and the core A is pulled out to the outside of the hole-saw 10 while it is slid in the cylindrical body 12 to complete the perforation operation.