Proceedings of JSPE Semestrial Meeting

In this paper, time domain simulation model was presented to calculate machining error and surface roughness with tool runout in ball end milling. Runout was measured by imaging tool silhouette during rotation. The presented model was verified by experiment with two fluted tool under wide rotation speed. Runout had a great influence on surface roughness when the harmonics of the tool rotation frequency except the tooth passing frequency is close to the frequency where the real part of the transfer function of the structure is minimum value.

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Recently, radius end mills have been developed to machine highly accurate and efficient three-dimensional shapes. But the cutting edge shape of the cutters is complex and there are few papers that focus on the radius end mill. Therefore, in this paper we geometrically analyze the theoretical roughness for inclined surface with the scanning method. At first, the equation for theoretical roughness is shown. Secondly, the surface roughness is measured by cutting tests and compared with the experimental results. Finally, it is shown that the estimated values of the theoretical roughness are almost coincident to the experimental values and analytical method for calculating the theoretical roughness is highly accurate.

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In this paper, a novel electrochemical machining (ECM) method to create holes with complex internal features was presented, in which a tool electrode with non-uniform surface resistance was adopted to shape the inner surface of the hole. The modeling and simulation of creation process of hole with complex internal features was carried out to investigate the electric potential distribution on the electrodes′ surface and in the electrolyte, and the evolution of the shape of inner surface of the hole. Effect of surface conditions of the tool electrode on the shape of the inner surface was also discussed. A prototype of the tool electrode with non-uniform surface resistance was fabricated to verify the feasibility of the proposed method. Simulation results showed that the proposed ECM method has the potential to create holes with complex internal features with relatively simple control system.

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Micro electrical discharge machining (EDM) is extensively used in high precision machining of conductive materials. In realizing the process, relaxation pulse generator is commonly utilized in micro EDM machine in order to achieve low discharge energy. Studies show that effective flushing and holes with high aspect ratio can be achieved if tool is rotated at very high speed. However, this is difficult to be realized using relaxation pulse generator since the power supply to the tool must be connected using brush and can cause vibration at high speed rotation. On the other hand, electrostatic induction feeding method allows tool to be rotated up to 50 thousand rpm without vibration because the electrical feeding is carried out by electrostatic induction. However, since small capacitance is formed in the narrow gap between feeding electrode and tool electrode holder, discharge energy per pulse is too small and insufficient to conduct rough machining. By controlling the duration of discharges, the discharge energy can be increased without limit by using the same small feeding capacitance. With this, numbers of small discharges are allowed to occur at the same location and thus size of discharge crater can be enlarged. In this study, crater size, removal volume per discharge crater and material removal rate (MRR) using controlled pulse train method were investigated and compared with the relaxation pulse generator under the same discharge energy.

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