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Kinematics and Geometry of Helical Chipping with Conical Helical Blades

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.org

Citation:  Transactions of the ASABE. 55(4): 1149-1158. (doi: 10.13031/2013.42233) @2012
Authors:   J. Wegener, T. Wegener
Keywords:   Auger, Chipper harvester, Chipping, Cone screw knife, Cutting process, Helical chipper, Machining technology, Tool geometry, Wood chips

The technique of helical chipping has not been well established on the market despite being able to produce large wood chips with a narrow variation in size. One reason for this is that the basic knowledge required for the optimization of such machines (e.g., how the individual tool parameters affect target variables such as power requirement, stability of the components under load, and quality of the wood chips) is still largely unknown. In this study, the tool geometry of helical chippers and their kinematics are explained by extrapolating from known relationships for standard machining technology and the mechanics of threaded connections. With this approach, the tool geometry of a conical helical chipper could be effectively characterized and shown to be influenced by many different parameters, which vary along the length of the blade and are dependent on its radius. In addition, the results show that important characteristics of the tool with respect to the kinematics of this method are determined by a helical chippers construction (i.e., cone angle, flank lead, and pitch). Other factors also play a role in the chipping process of a helical chipper, such as the feed motion per blade, which depends on the material characteristics of the workpiece and influences the interplay between the workpiece and the blade. This study is a first attempt to develop a better theoretical understanding of helical chipping. Based on the presented findings, the interaction between the tool and workpiece needs to be investigated next.

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