Sub-scale Machining of Large Components
1 online resource (86 pages) : PDF
University of North Carolina at Charlotte
This research examines the feasibility of machining components with precise tolerances using machines smaller than the completed part. This can conceptually be achieved in two ways. 1.) move a part around a machine, machining a portion of the part at a time, resulting in a completed part; and 2.) move a machine/multiple machines around a part, machining a portion of the part at a time, resulting in a completed part. At each step, a laser tracker was used to measure the spatial relationship between the part and machine coordinate systems (CS); and custom software was developed to read the part coordinates from the NC part program and replace them with the values corresponding to the new part/machine spatial relationship.Several series of parts were machined to allow the determination of additional error from the laser tracker to the manufacturing process, and the precision of transitional areas between machined sections. A final test included machining a set of parts larger than the machine's working area to determine tolerances the machining process is capable of and demonstrate the project objectives have been met. Initial test parts showed part feature errors significantly larger than initially expected. A search for the cause of errors led to process improvements which showed the importance of proper measurement techniques to reduce influences from machine tool geometric errors and the importance of proper fixturing. After correcting for machine tool geometric errors and using proper fixturing techniques, part feature location errors were reduced to an expected value. A variability analysis of the sub-scale machining process was performed to compare experimental and theoretical part feature errors. The variability analysis showed expected part feature errors on the order of experimental values. Sub-scale machining is capable of producing 2D parts with feature location errors on the order of the uncertainty of the reference metrology device.Initial test parts showed the capabilities of sub-scale machining when used to make essentially two (2) dimensional parts. An analysis of the sub-scale machining process was performed to understand the capabilities of sub-scale machine as an operation to produce large three-dimensional parts with features on multiple sides. It is expected that sub-scale machining can produce features on multisided parts with orientation errors on the order of a few tenths of a milliradian.
FIDUCIALSLARGE PARTSLARGE SCALE MACHININGLASER TRACKERMANUFACTURINGSMALL MACHINE
Morse, EdwardDavies, MatthewMiller, Jimmie
Thesis (M.S.)--University of North Carolina at Charlotte, 2015.
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