| Summary: | 碩士 === 國立臺北科技大學 === 製造科技研究所 === 99 === Face milling is one of the most common milling processes in metal cutting. How to select the entrance angle for face milling is an important scheme, because it affects the machined surface quality and the cutting tool life very much. The purpose of this study is to investigate the milling forces, tool wear, machined surface roughness, and the stresses induced in the tool insert under different entrance angles of face milling operations, and illustrate the influences and importance of entrance angles in face milling. To compare the effects in face milling, 6 different types of entrance angles, -20°, -10°, 0°, 30°, 60° and 75°, are included. And, there are 3 feedrates and 3 cutting depths for each entrance angle. The material used for face milling experiments is nodular cast iron FCD700 with machining surface of 30 mm (width) × 200 mm (length). The diameter of the face cutter is 100 mm, with only one tool insert installed (tungsten carbide), for all milling experiments. Using only one insert eliminates the influences of tool run-out and deviations among inserts during milling. All the milling speeds and tool feedrates used in present experiments were adequately referred to the tools catalog. The experimental results show the entrance angles that near zero bring to larger horizontal cutting forces acted on the face cutter during milling. It is to say, with larger entrance angle or larger minus entrance angle (such as 75° and -20° in present study), the maximum horizontal cutting forces will be reduced; however, duration of the real cutting time in one revolution will be longer. In comparison of machined surface roughness, it reveals better machined surface can be obtained by using larger entrance angles (or larger minus entrance angles) because of more densely cutting texture compared with small entrance angles. In the tool wear experiments, the milling condition of 75° entrance angle causes the maximum flank wear while 30° entrance angle causes the minimum in present study. Finally, the paper uses a mechanistic face milling force model to predict the tangential, radial, and axial forces acted on the tool insert during milling. By using the model, we can analyze the stress distribution in tool insert during milling for each cutting condition. The simulated results show that the face milling with larger entrance angle generates larger equivalent stress on the main cutting edge.
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