Study on Non-Axisymmetric 3D Curved Surface Turning by Driven-Type Rotary Tool Synchronized With Spindle

Since shifting to electric vehicles as a countermeasure against global warming is hard to complete, the hybrid car has been considered as another possible solution. However, based on the calculation of total CO₂ emissions, all hybrid cars which will constitute 90% of all cars are expected to be equipped with an internal combustion engine even after 2030. Therefore, further efficiency improvement of the internal combustion engine is necessary. One of the key factors is the variable valve timing and variable lift of the cam mechanism. Since conventional technology uses a complicated link mechanism and servo motor control, this creates a problem to build small cars or two-wheeled vehicles because they are not big enough for the size and weight of the two important parts: the variable valve timing and variable of cam mechanism, which won’t fit. To solve this problem, a cam shape with a three-dimensional curved surface has been proposed. In order to create this shape, the machining method for non-axisymmetric curved surface turning (NACS-Turning) is required. To build the new system, our research group has proposed a new machining method using a driven rotary tool and a linear motor driven moving table to enable to achieve NACS-Turning. In this new system, a new tool rotation axis (B axis) is adopted to synchronize its rotation position with the rotation position of the spindle (C axis) holding the workpiece and the X₁-, X₂-, and Z-Axis positions in total. In this paper, the new hardware configuration is proposed to overcome the present machining accuracy from the point of non-circular machining method.