LATHE TURNING

PURPOSE:To shorten working time by tilting the edges of tools in opposite tool posts in the same direction, shifting the edges by the same amount in the same direction relative to the center of a workpiece, and cutting the long workpiece by a NC lathe from both directions to machine it while keeping balance without producing chattering. CONSTITUTION:When a long workpiece 4 is cut, a tool 7 of an upper tool post is fixed into a turret reversely to the workpiece 4 for cutting it simultaneously by both the tool 7 and a tool 11 of a lower tool post. The edges of the tool 7 and the tool 11 are shifted upward by the same amount relative to the center of the workpiece. A depth of cut is given to the workpiece in the X axis and the workpiece is cut with concurrency control by a NC. The main component of force F1 of the tool 7 and that F2 of the tool 11 are nearly offset since their positions are not so deviated. The back component of force F2 of the tool 7 can be divided into components F3 and F4 and the back component of force F6 can be divided into components F7 and F8. Accordingly, the components of force F3 and F7 are offset, the components of force F4 and F8 remain and a resultant force F4+F8=F is always exerted on the workpiece in the direction A.