1995 Fiscal Year Final Research Report Summary
Molecular Dynamics Analysis of Mechanical Surface Generation Process at Atomistic Level
| Project/Area Number |
05402030
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| Research Category |
Grant-in-Aid for General Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
機械工作・生産工学
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| Research Institution | Osaka University |
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Principal Investigator |
IKAWA Naoya Osaka Univeristy, Department of Precision Engineering, Professor, 工学部, 教授 (60028983)
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| Co-Investigator(Kenkyū-buntansha) |
UCHIKOSHI Junichi Osaka Univeristy, Department of Precision Engineering, Research Associate, 工学部, 助手 (90273581)
SHIMADA Shoichi Osaka Univeristy, Department of Precision Engineering Associate Professor, 工学部, 助教授 (20029317)
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| Project Period (FY) |
1993 – 1995
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| Keywords | Micromachining / Diamond turning / Computer simulation / Cutting mechanism / Machining accuracy / Molecular dynamics / Cutting temperature |
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| Research Abstract |
To understand the chip removal and surface generation mechanisms and for the quest of ultimate accuracy attainable in micromachining of metals, a feasibility study is proposed based on molecular dynamics (MD) computer simulation. MD simulation is confirmed to be a useful method to analyze accurately the atomistic behavior of the workmaterial around the cutting edge in cutting process.
Due to plowing of the cutting edge, many dislocations are generated successively in the workpiece near the tool-workpiece interface. Some of them move into the shear zone and disappear from the free surface. As a result of succesive generation and disappearance of the dislocations, the chip seems to be removed stably. The other dislocations penetrated into the workpiece beneath the cutting edge move back and finally disappear from the worksurface due to spring back of the workpiece after the passage of the cutting edge. As a result of the relaxation, atomistic steps are formed on the worksurface. The hight
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of the steps remaining on the worksurface can be considered as the ultimate surface roughness attainable in microcutting.
Apart from machine tool performance, there are two primary factors affecting the ultimate accuracy attainable in micromachining. One is the minimum thickness of cut (MTC), which is the minimum uncut chip thickness stably removed from a worksurface at a cutting edge. The other is transfer fidelity of the cutting edge profile to the worksurface, which is of the same level as the ultimate surface roughness. MD simulations show that MTC and transfer fidelity in microcutting of copper is 1/20 to 1/10 of the radius of the cutting edge, that is about 1 nm for a realistic diamond cutting tool, and about 1.0 nm, respectively. In cutting of aluminum, a larger MTC and transfer fidelity, which are 1/10 to 1/5 and 2.0 nm, are estimated.
By the introduction of a kind of "scaling" in thermal conductivity for which electron conduction is to be taken into account, the cutting temperature in microcutting can be reasonably analyzed. Less
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