B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
B23B—TURNING; BORING
B23B5/00—Turning-machines or devices specially adapted for particular work; Accessories specially adapted therefor
B23B5/36—Turning-machines or devices specially adapted for particular work; Accessories specially adapted therefor for turning specially-shaped surfaces by making use of relative movement of the tool and work produced by geometrical mechanisms, i.e. forming-lathes
B23B5/40—Turning-machines or devices specially adapted for particular work; Accessories specially adapted therefor for turning specially-shaped surfaces by making use of relative movement of the tool and work produced by geometrical mechanisms, i.e. forming-lathes for turning spherical surfaces inside or outside