The invention discloses a special portal type numerical-control milling
machine for efficiently milling an arc-shaped surface of a tool. The special portal type numerical-control milling
machine comprises a portal lathe body (1), an orthogonal dragging plate (2), a Z-direction dragging plate (3), a main shaft base plate (4), tapered iron (5), a movable
workbench (6) and an electromagnetic
workbench (7). According to the special portal type numerical-control milling
machine disclosed by the invention, the inclined iron is lined between the Z-direction dragging plate and the main shaft base plate, so that the rotation axis of an electric main shaft and the up-down motion axis of the Z-direction dragging plate form an inclination angle of 45 degrees; during working, a disc-shaped
milling cutter performs intercross milling on a main rear surface of a hand
hay cutter workpiece in a mode that the
cutting rotation axis and a
cutting feeding direction tilt at an angle of 86 degrees so as to form the arc-shaped surface; the tilting mode enables the small-
diameter disc-shaped
milling cutter to meet milling forming for the arc-shaped surface of the main rear surface of the hand
hay cutter workpiece, so that the tool cost is reduced, and milling vibrations are reduced, and therefore, the technical scheme of deep-feeding, quick-advancing and heavy-load efficient milling can be achieved; andmilling
processing for the arc-shaped main rear surface hand
hay cutter by a paper cutter is achieved, and therefore, the purposes of improving efficiency, reducing cost and suitable for large-scalebatch production are achieved.