| 摘要 |
A method of drilling counter sink holes is provided to widen the diameter and form inclined surfaces on a drilled hole at the same time by installing rimming and coining cutters on upper and lower molds, and placing the cutters on the drilled holes and rotating the cutters, thereby eliminating the separate processes for forming inclined surfaces. A method of drilling counter sink holes comprises the steps of: drilling a hole on a transported material(10) by using a piercing punch(11) installed on upper or lower molds; widening the drilled hole to a predetermined diameter by inserting and rotating a rimming cutter(20) installed on upper or lower molds into the drilled hole; forming an inclined surface(3) on an upper part of the drilled hole by placing and rotating a coining cutter(30a) installed on the upper mold on the material, wherein the coining cutter has an inclined part(31) on an front end; and forming an inclined surface on an lower part of the drilled hole by placing and rotating a coining cutter(30b) installed on the lower mold on the material. A coining cutter combined with a rimming cutter is installed on the upper mold and is placed on the lower part of the drilled hole and rotated, forming the inclined surface and widening the diameter of the hole at the same time. A coining cutter combined with a rimming cutter is installed on the lower mold and is placed and rotated on the lower part of the drilled hole, forming the inclined surface and widening the diameter of the hole at the same time. |
