| Summary: | 碩士 === 國立中興大學 === 機械工程學系所 === 95 === The purpose of this thesis is to investigate the methods for improving the automatic process of machining aircraft angled aluminum parts. The specific interest is in the parts with features of the material stock length between 0.5” and 120”, thickness of 0.04” to 0.25”, a variety of types and shapes with JOGs (inclined surfaces) or curved fitting profiles. The objective is to provide solutions for the improvements of the machining plan after flattening, designs of clamps and spindle chucks and control of deformation after machining process, such as to establish the relationships between the modifications of the machining process and the improvements on the surface roughness.
Beginning with practical considerations and being followed by application of Taguchi method, hopefully, an optimal combination of parametric values is obtained. The factors taken into considerations include the planning of machining manufacturing process, cutting force and types of clamping, the design of clamps and spindle chucks, the selection of cutting tools and cutting parameters and arrangement of cutting paths. Firstly, fish-bone diagrams and machining empirical data are used as the basis for the screening process on deciding machining conditions, which include the spindle speed, feed rate, cutting depth, tool radius, tool characteristics, flute number, stock thickness, material property, cutting direction, clamping length and spinning position. Then, orthogonal table L12211 is used to arrange 12 experiments which are conducted to generate the angled parts. Subsequently, the surface roughness for each part is measured to establish an optimal combination of parametric values for the machining process.
This research provides a locally optimized machining process plan for angled aluminum parts. The acquired machining parameters for obtaining optimal surface roughness are: high spindle speed, high feed rate with low cutting depth or low feed rate with high cutting depth, tungsten carbide tool with diameter 3/8” and length 3.0”, clamping length of 6” as a division point, fixed down milling and appropriate retraction and engaging procedures. It is hoped that the related methods and acquired parameters adopted in this research can help to improve the surface roughness resulted from an automatic machining process of aircraft angled aluminum parts.
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