Patent ID: 8864425
Filing Date: 2014-10-21
Classification: B23B,B23C,Y10S,Y10T

Abstract:
1. A bevel head replaceable rotary tool having a shaft-like tool body and a bevel head, formed as a separate body from the tool body, which is detachably mounted on the tool body at a leading end thereof in a concentric relation thereto, the rotary tool comprising: a coupling protrusion, provided on the bevel head and a coupling recess provided on the tool body, each of, which are non-circular in shape in cross section perpendicular to a tool axis “O” and are provided for fitting engagement in a tool axis direction; serrations having plural protrusions, separated in the tool axis direction, which are provided on an outer circumferential surface of the coupling protrusion and an inner wall surface of the coupling recess, respectively, and one of the serrations of the coupling protrusion and a corresponding one of the serrations of the coupling recess together constituting a set of serrations, the serrations of the coupling protrusion and the corresponding serrations of the coupling recess together constituting plural sets of serrations to be separate from each other in circumferential directions under which rotating the tool body about the tool axis “O” relative to the bevel head in a tool rotating direction with the coupling protrusion and the coupling recess held in fitting engagement in the tool axis direction allows the plural protrusions of the serrations of the coupling protrusion and the plural protrusions of the serrations of the coupling recess to mesh with each other in each of the plural sets of serrations, such that the bevel head is blocked from escaping from the tool body in the tool axis direction; circumferential abutting portions provided on the tool body and the bevel head, respectively, which are abutted with each other when the tool body is caused to rotate (about the tool axis “O”) relative to the bevel head in the tool rotating direction with the plural protrusions held in meshing engagement such that a mounting phase about the tool axis “O” is defined; and axial tight-contact portions, provided on the tool body and the bevel head, respectively, which are brought into tight contact with each other in the tool axis direction under predetermined pressing loads on the mounting phase when the tool body is caused to rotate relative to the bevel head in the tool rotating direction with the plural protrusions held in meshing engagement, the serrations of the coupling protrusion and the serrations of the coupling recess being arranged such that curvatures of circumferential circular arcs of the serrations of the coupling protrusion are made greater than those of the serrations of the coupling recess or the serrations of the coupling protrusion and the serrations of the coupling recess have circumferential circular arcs with centers deviated from each other whereby when the tool body is caused to rotate relative to the bevel head in the tool rotating direction, the plural protrusions are brought into meshing engagement with each other, the serrations of the coupling protrusion and the serrations of the coupling recess having inclined angles φ falling in a range of 0°≦φ≦15° from directions perpendicular to the tool axis “O” and the inclined angle φ of at least one of the serrations of the coupling protrusion and the serrations of the coupling recess being positive to allow the bevel head and the tool body to move closer to each other in the tool axis direction when the tool body is caused to rotate relative to the bevel head in the tool rotating direction with the serrations held in meshing engagement with each other, and the axial tight-contact portions, provided on the tool body and the bevel head, respectively, having flattened tight contact surfaces nearly perpendicular to the tool axis “O” for engagement in surface contact with each other.