DEVICE FOR FORMING BORING HAVING UNDERCUT PART

摘要

PURPOSE: To provide an apparatus for making a boring hole with an undercut in an armoring plate in particular. CONSTITUTION: A boring device 1 with boring tools 15 is vertically movable along a stand 3 through a supporting device 7. The sleeve 10 fixedly joined to a boring machine 12 through a bearing bush 9 is rotatably and turnably mounted through a revolving bearing. The boring machine 12 is provided with a lever 35 whose end is joined to a crank, and the lever 35 is tiltable together with the crank, and at least one peg 37a arranged in the crank can describe a circle about a center line of the lever 35 in the outer circumferential surface of the cam disk 39 connected to the stand 3 when the peg 37a engages on the circumferential surface.