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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Development of a Five-Axis Machining Algorithm in Flat End Mill Roughing

Thompson, Michael Blaine 16 May 2005 (has links)
To further the research done in machining complex surfaces, Jensen [1993] developed an algorithm that matches the normal curvature at a point along the surface with the resultant radius formed by tilting a standard flat end mill. The algorithm called Curvature Matched Machining (CM2) is faster and more efficient than conventional three-axis machining [Jensen 1993, Simpson 1995 & Kitchen 1996]. Despite the successes of CM2 there are still many areas available for research. Consider the machining of a mold or die. The complex nature of a mold requires at least 20-30 weeks of lead time. Of those 20-30 weeks 50% is spent in machining. Of that time 50-65% is spent in rough machining. For a mold or die that amounts to 7 to 8 weeks of rough machining. If one could achieve as much as a 10-15% reduction in machining time that would amount to almost one week worth of time savings. As can be seen, small improvements in time and efficiency for rough machining can yield significant results [Fallbohmer 1996]. This research developed an algorithm that focused on reducing the overall machining time for parts and surfaces. Particularly, the focus of this research was within rough machining. The algorithm incorporated principles of three-axis rough cutting with five-axis CM2, hence Rough Curvature Matched Machining (RCM2). In doing so, the algorithm ‘morphed‘ planar machining slices to the semi-roughed surface allowing the finish pass to be complete in one pass. This roughing algorithm has significant time-savings over current roughing techniques.
2

Global Finish Curvature Matched Machining

Wang, Jianguo 18 November 2005 (has links) (PDF)
As competition grows among manufacturing companies, greater emphasis has recently been placed on product aesthetics and decreasing the product development time. This is promoting and standardizing widespread use of sculptured surface styling within product design. Therefore, industries are looking for high efficiency machining strategies for sculptured surface machining (SSM). Many researchers have produced various methods in tool path generation for SSM. Five-axis curvature matched machining (CM2) is the most efficient. With the widespread use of 5-axis mill in industries, CM2 is a better solution for improving the machining efficiency for product concept models. CM2 has very good performance for global machining of single patch surface or a quilt of simple sculptured surface patches. But when CM2 is used to generate tool paths for global machining of a large region of complex sculptured surface such as the top or side skins of a vehicle, there will be some limitations, that is, the performance will be influenced greatly in some steep areas where the lead angle of the tool becomes larger to match the curvature or avoid gouging. Larger lead angles mean smaller effective curvatures at the leading edge of the tool bottom where it contacts the part surfaces. Therefore, the density of CM2 tool path is very high in these steep regions. By setting a smaller upper limit for the lead angle, the density of tool path will not be very high in the steep regions, but there will be some uncut materials. This thesis focuses on how to determine the uncut or rework areas of the previous CM2 and how to define the boundary of these regions. Strategies for generating more efficiency CM2 tool paths are also discussed. These methods will be tested by applying finish global machining to a one-fourth scale Ford GT model.

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