| Summary: | 博士 === 國立台灣工業技術學院 === 機械工程技術研究所 === 85 === ABSTRACT The large-deformation strain
finite element theory, the updatedLagrangian formulation(ULF)
and incremental principles were used inthis paper to develope a
two-dimensional thero-elastic-plastic analyticalmodel. In this
model, the tool moves forward step by step from the initialtool-
workpiece contact till the formation of steady cutting force.
Firstly, based on the above model, it was analyzed that OFC
copper wasmachined by diamond tool with zero rake angle. The key
point is to observethe effects of both cutting speed and
temperature to workpiece material.Along the predefined cutting
tool path, the geometrical chip separation criterion was used to
separate the workpiece node into chip node and machined
workpiece node. To understand the effects of the amounts of
elastic deformationand crater of cutting tool subjected high
cutting force and stressin the chip-tool interface. Under the
condition of low cutting speed and no heat transfer, The tool
considered as elastic material is the secondstage key point. The
iteration mathematical model in the chip-tool interface was
developed, and three kinds of tools were applied to machinemild
steel workpiece. By using the above iterative model, the effects
of different tools under the condition of zero rake angle to
cutting processwere investigated. The study of 6-4 copper
incipient discontinuous chip formation is thekey point in the
final stage. The initial fracture position of chip waspredicted
using accumulated strain energy density and the growth
orientation of fracture was found using the direction of maximum
strain energy density.As a result, the discontinuous chip
configuration, cutting force and stress, strain distributions
can be obtained.
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