Method and apparatus for manufacturing an article in the form of a scroll

An apparatus for manufacturing a work including a scrollwall which is formed into an involute portion at other than opposite ends thereof, the involute portion having inner and outer wall surfaces forming involute curves having the same circle as a basic circle, comprising:

• rotation means for rotating the work about the center of the basic circle,
• X-axis drive means for relatively moving a tool and the work along the X-axis corresponding with a radial direction of the basic circle,
• Y-axis drive means for relatively moving the tool and the work along a Y-axis corresponding with a radial direction of the basic circle and normal to the X-axis, and
• drive control means for controlling the rotation means, X-axis drive means and Y-axis drive means, such that:
• the tool is brought into contact with a radially outer part of one wall surface of the involute portion at a position displaced from the center of the basic circle by a radius of the basic circle in one direction along the Y-axis from a normal direction of the wall surface,
• the one wall surface is processed toward its radially inner part by relatively moving the tool and the work in one direction along the X-axis parallel with a tangential direction of the basic circle while rotating the work in one direction about the center of the basic circle,
• the tool is brought into contact with a radially inner part of the other wall surface at a position displaced from the center of the basic circle by the radius of the basic circle in a direction opposite from the one direction along the Y-axis from the same side as the processing of the one wall surface along a normal direction of the other wall surface, and
• the other wall surface is toward its radially outer part by relatively moving the tool and the work in the same direction as the one direction along the X-axis while rotating the work in a direction opposite from the one direction about the center of the basic circle.