Elbow formed by cutting and method for manufacturing same

摘要

A hole is formed in an elbow through the steps of: forming a starting hole in a material, the starting hole having an undercut remaining on a hole surface; finishing an inner diameter of the starting hole (11−3) on one end side by revolving a side cutter (II) including an arc-shaped cutting edge and having an outer diameter smaller than a finishing hole diameter while rotating the side cutter (II) in such a posture that the side cutter (II) is inclined in a predetermined direction relative to the material (12), the revolving being carried out so that the side cutter moves along a hole surface to be finished; and finishing the inner diameter of the starting hole (11−3) on another end side by revolving the side cutter (II) while rotating the side cutter (II).

主权项

1. A method of manufacturing an elbow (10) by machining, comprising forming a hole (11) in a material (12) to be formed into the elbow (10), said forming of the hole (11) comprising:
forming a starting hole (11−3) in the material (12) by rough cutting of the material (12) from two directions with a rotary cutting tool, the starting hole (11−3) having an undercut (13) remaining at least on a hole surface on a side which corresponds to an inner side of a bend of the elbow as a finished product; finishing a radially inner surface of the starting hole (11−3) on one end side using a side cutter (II) including an arc-shaped cutting edge (5) at an outer periphery thereof and having an outer diameter smaller than a finished hole diameter, wherein the side cutter (II) is inclined at a predetermined angle (θ4) relative to the material (12) such that an end surface of the side cutter (II) is more remote from an opening of the starting hole (11−3) on the inner side of the bend of the elbow to be cut, and is cut into the surface of the starting hole (11−3), while simultaneously revolving the side cutter and rotating the side cutter about a center axis of the side cutter, such that the hole (11) has a completely circular cross section taken along a plane perpendicular a center axis of the hole (11) and perpendicular the center axis of the side cutter, and an oval cross-section taken along any plane not perpendicular to the center axis of the hole (11) and perpendicular to the center axis of the side cutter, whereby the side cutter moves along the surface of the hole (11), and finishing the radially inner surface of the starting hole (11−3) on another end side by inserting the side cutter (II) into the starting hole (11−3) from the another end side of the starting hole, and revolving the side cutter (II) along the hole surface to be finished while rotating the side cutter (II).