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005			20260817161527.0
008			130799s1998 th uzm rtt 00| a1eng d
035			_a.b11754849
099		9	_aAIT Diss. no. ISE-98-02
100	0		_aKawin Sonthipermpoon
245	1	0	_aAdaptive non-linear grid tool path optimization for five-axis machining
260			_aBangkok : _bAsian Institute of Technology, _c1998
300			_a63 p.
490	1		_aDissertation ; _vno. ISE-98-02
500			_aA dissertation submitted in partial fulfillment of the requirement for the degree of Doctor of Engineering, School of Advanced Technologies
502			_aThesis (Ph.D.) - Asian Institute of Technology, 1998
520			_aInnovations in the field of manufacturing system engineering have enhanced the employment of milling machines in various manufacturing processes. Guided by computers, they can produce free-shape surfaces to supply the needs of the mass manufacturing industries of automobiles, airplanes, ships, etc. Five-axis machines have become capable of handling geometrically complex workpieces. Moreover, the most modern machines are characterized by high material removal rates and excellent surface finish. Unfortunately, several physical phenomena, such as: machine kinematics, thermal effects, static and dynamic loading, common-cause failures, clamping and spindle of cutting devices tend to affect the quality of surfaces. Kinematic machine errors - the most significant impediments of their employment - are the main objective of this research. Traditionally the tool path generated by a computer aided manufacturing system approximates the surface as a piecewise linear curve. On a three-axis CNC machine the curve followed by the cutter location point and the cutter contact point will be the same piecewise linear curve. However in 5-axis milling the path between two successive cutter location or cutter contact point will be curved due to the simultaneous linear interpolation in rotary and linear machine axes. Instead 6f conecting this "tool path curvature" error in the post-processor, the cutter location tool path will be generated so that this curved tool path approximates the surface with in the required tolerances. The results of this are smoother and more accurate surface quality and a considerable smaller number of cutter location points for the same surface. This new algorithm for the optimization of the tool-paths of five-axis machines is based on global approximation of the desired surface by a virtual surface comprising tool trajectories. In order to construct a suitable grid generator, let the global spatial error be defined as the difference between the required surface and the surface generated by non-linear trajectories. The elliptic grid techniques [Thompson J.F. 1993 and Ivanenko S.A. 1993], [Brackbill J.U. 1982], based on the optimization of the following properties, is modified: Smoothness of the grid, adaptively to regions of large milling errors and a particular constraint related to the prescribed tool diameter and scallop height. A numerical solution of the constrained minimization problem is developed employing the iterative algorithm which penalizes large scallop height and maximum difference between the real surface and toolpaths surface. The capability of the algorithm to generate tool-paths for sculptured surfaces with complex, boundaries is increased by introduction of zigzag-adaptive patterns.
650		0	_aMachine-tools _xNumerical control
700	1		_aBohez, Erik L.J., _eChairperson
700	1		_aTabucanon, Mario T., _eExamination Committee
700	1		_aBatanov, Dentcho N., _eExamination Committee
700	1		_aMakhanov, Stanislav S., _eExamination committee
700	1		_aKruth, Ir. Jean-Pierre, _eExamination committee
710	2		_aRoyal Thai Government, _eScholarship donor
810	2		_aAsian Institute of Technology. _tDissertation ; _vno. ISE-98-02
856			_3Full-Text _uhttp://203.159.5.9/ait-thesis/detail.php?q=B12940
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