Machining head replaceable rotating tool, holder, and machining head

A machining head replaceable rotating tool having a fastening male screw and a fastening female screw disposed on respective shaft centers of one and the other of a machining head and a holder, the fastening male screw and the fastening female screw being threadably engaged with each other to concentrically and removably attach the machining head to a tip portion of the holder,

• the machining head and the holder being disposed with abutting surfaces abutted against each other in a fastened state when the fastening male screw and the fastening female screw are threadably engaged,
• the machining head replaceable rotating tool being integrally and rotationally driven via the holder in a tool rotation direction causing the fastening male screw and the fastening female screw to be fastened by a machining load to perform predetermined machining with the machining head, the abutment of the abutting surfaces preventing the fastening male screw and the fastening female screw from being further fastened by a machining load,
• the fastening male screw and the fastening female screw being made up of saw-tooth buttress screws having a flank angle α of a following flank smaller than a flank angle β of a leading flank,
• the holder being disposed with a through-hole penetrating a shaft center, wherein at least a portion of the through-hole is disposed with a removal female screw,
• the machining head replaceable rotating tool having a removal aiding pin inserted into the through-hole from a back end of the holder and threadably engaged with the removal female screw with a tip portion abutted against the machining head to press and push out the machining head when the threadable engagement between the fastening male screw and the fastening female screw is loosened to remove the machining head from the holder,
• an engagement projection and an engagement recess in a conical shape fitted in surface contact with each other being respectively disposed on shaft centers at abutting locations of the removal aiding pin and the machining head, and
• the through-hole being disposed with a positioning hole having a circular cross section at a portion adjacent to the fastening female screw, and the removal aiding pin being disposed with a column-shaped positioning fitting portion slidably fitted with the positioning hole, and
• the through-hole being disposed with a larger diameter hole than a major diameter of the fastening female screw on the back end of the holder, wherein the larger diameter hole receives a head portion disposed on a back end of the removal aiding pin, wherein the head portion is a largest diameter portion of the removal aiding pin.