Papers by Author: M. Ham

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Authors: Alexander Szekeres, M. Ham, J. Jeswiet
Abstract: Forces are measured in Single Point Incremental Forming with a spindle mounted sensor. Results for AA3003 aluminum cones and pyramids are shown. Forces are measured for parts with a 75° forming angle, at which shear cracks are expected to occur. Forces in the three directions are measured on the spindle with force spikes being observed when the tool changes direction at pyramid corners, and reductions in force when stepping between contours. There is also a force variation as the forming tool moves along the pyramid wall. A comparison is made between the forces measured for cones and pyramids.
Authors: J. Jeswiet, David J. Young, M. Ham
Abstract: Although not standard, Forming Limit Diagrams, FLD’s, are used throughout the automotive industry as a preliminary tool to determine if a sheet metal forming process is capable of forming a good part. FLD’s show a limited range of strains on the diagram; typically the range is 0 to 1 on the major strain axis. A new rapid prototyping process called Single Pont Incremental Forming, SPIF, experiences strains over 3. As FLD’s do not typically cover that level of strain, a new method for developing FLD’s is needed. Such a method is proposed in this paper. Research has been conducted with five different shapes, formed using Single Point Incremental Forming. The part shapes utilized contain the most common combinations of angles and curves observed in formed sheet metal products. The strains encountered in forming each of these parts are measured and the strain data is then plotted on the same FLD. These new FLD’s can then be utilized as a predictive tool for engineers to determine if their design can be produced using the SPIF process.
Authors: M. Ham, J. Jeswiet
Abstract: Single Point Incremental Forming (SPIF) is a new method of forming sheet metal for which not all forming limits and forming parameters are yet completely understood. In this paper, a Box-Behnken design of experiment (DOE) is used to execute an experimental study used to determine the forming limits in Single Point Incremental Forming (SPIF). The Box-Behnken allows for good accuracy in defining a surface response for a relatively low number of experimental runs – hence its usefulness in experimental work. The Box-Behnken used in this paper solved five factors at three levels in forty six runs. The five factors analyzed are based on the most critical factors effecting SPIF; they are material type, material thickness, formed shape, tool size and incremental step size (depth of each step in form). The data resulting from the Box-Behnken progressed into graphical response surfaces; the response surfaces allow designers to determine what factors they need to select in order to successfully form a part using SPIF.
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