. Free-form surfaces are used in many aspects of the industry. When machining these surfaces using three-axis ball-end milling, the tool's working diameter continuously changes, due to the change in the surface geometry which affects the surface quality. This change in working diameter occurs from one point to another and continues along the surface even in the case of a constant tool path. Using a simultaneous five-axis milling machine can solve the problem, however, this solution comes at a high cost and complexity. This paper gives insight into the calculation of the effective diameter at each point of the milled surface and presents the effect of the different parameters by simulation. The simulation applies the geometric method, based on the coordinate transformation of the intersection curve. The presented simulation approach ensures optimization method for both the cutting process and the tool path. The ultimate goal is to reduce the cutting speed change considering the change of the current working diameter by controlling the spindle speed point to point, resulting in a more homogeneous surface.

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Simulation of the Working Diameter in 3-Axis Ball-end Milling of Free Form Surface

Ball end mill cutter is widely used in precise CNC machining as a high efficiency processing tool for complex surface. On the basis of the literature review about mathematical model, grinding machining process, cutting experiment of ball end mills, and the calculation for a ball end mill, a ball end mill parametric design system is built by development technology with CATIA 3D modeling software and Visual Basic. With this system obtaining the model of the ball end mill, the simulation is processed in Third Wave AdvantEdge software. 
The main contents of this paper are:
1. On the basis of creating a mathematical model of a ball end mill cutting edge curve, we generate the 3D model of the cutter in CATIA. Moreover, the conditions of the engagement between the grinding wheel and rake surface to avoid interference are proposed. As a result, the grinding wheel center location and orientation axis are defined.
2. A modeling program for ball end mills is developed in Visual Basic, and the parameter modification can be visualized in the interface of this program .In addition, the model is simulated in Third Wave AdvantEdge to analyze the temperature of the cutter and the cutting force distribution.
KEY WORDS: Ball End Mill, Parametric Design, CATIA Secondary Development, Simulation

Liyong Chang

Papers

A Parametric Design of Ball End Mill and Simulating Process