Studying Curve Interpolator for CNC System


This thesis focuses on developing algorithm to calculate best length linesegments in (u) and (w) directions. By of tool paths for free form surfaces basedon the required accuracy of the manufactured part, which is represented bymathematical curves and surfaces. Bezier method was used to apply the proposedalgorithms. The proposed algorithms consist of two parts; the first part is tocalculate the better length line segment in (u) direction between cutter contactpoints (CC), the second part is to calculate the better line segment in (w) directiondepending on the type of surface, cutter radius, tolerance and height scallop beinggiven. The algorithms are applied in production field such as design of extrusiondies using three types of curve interpolation such as approximation cubic Bezier,interpolator Bezier and compound-CRHS profile die. In this paper, themanufactured parts are machined using a 3-axis CNC milling machine. Themachining operations are simulated using SURFCAM software depending on thedifferent interpolation techniques mentioned. An evaluation test is applied to thethree interpolation methods based on Finite Element Method (FEM) usingANSYS 9.0 software to expect the strain and force required to extrude billetthrough the dies which are designed using the three mentioned interpolationmethods. The G-code programs have been implemented on 5-axis CNC machine(Okuma VH-40-HS dynamic machine), the sample material is (cibatool) and themachining process is achieved without a lubricant at the Protoshop Oy inHelsinki/Finland.