Ultraprecision Machining of Hybrid Freeform Surfaces Using Multiple-Axis Diamond Turning

Ultraprecision Machining of Hybrid Freeform Surfaces Using Multiple-Axis Diamond Turning
اسم المؤلف
Dennis Wee Keong Neo
التاريخ
13 مايو 2023
المشاهدات
349
التقييم
(لا توجد تقييمات)
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Ultraprecision Machining of Hybrid Freeform Surfaces Using Multiple-Axis Diamond Turning
Doctoral Thesis accepted by National University of Singapore, Singapore
Dennis Wee Keong Neo
Contents
1 Introduction 1
1.1 Hybrid Freeform Surfaces 2
1.2 Ultraprecision Machining of Hybrid Freeform Surfaces . 5
1.3 Main Objectives of This Dissertation . 6
1.4 Organization of This Dissertation 6
References 7
2 Literature Review . 9
2.1 Multiple-Axis Ultraprecision Diamond Machining
Techniques . 9
2.1.1 Fast Tool Servo (FTS) 10
2.1.2 Slow Slide Servo (SSS) . 14
2.1.3 Other Multiple-Axis Ultraprecision Machining
Techniques . 16
2.2 State-of-Art CAD/CAM/CAE Technologies 18
2.2.1 CAD/CAM Technology for Surface Generation . 18
2.2.2 Surface Accuracy and Error Compensation Approaches 19
2.3 Concluding Remarks . 22
References 23
3 Initial Development of CAD/CAM Technologies . 27
3.1 CAD/CAM for Multiple-Axis Ultraprecision Machining
Processes 28
3.1.1 Non-uniform Rational B-Spline Freeform Surfaces . 28
3.1.2 CAD/CAM Interpolator for FTS/SSS
Diamond Turning 29
3.2 API Methodology for CAD/CAM Software Development . 31
3.2.1 Experimental Validation . 34
3.3 Concluding Remarks . 38
References 38
xi4 Development of Hybrid FTS/SSS Diamond Turning . 41
4.1 Principle of Layered Tool Trajectory . 41
4.2 Layered Tool Trajectory Control 43
4.3 Experimental Validations 47
4.4 Concluding Remarks . 50
References 51
5 Novel Surface Generation of Complex Hybrid Freeform Surfaces . 53
5.1 Novel Surface Generation for Automated Guilloche Machining
Technique 53
5.2 Experimental Validations 55
5.2.1 Critical Machining Parameters 56
5.3 Concluding Remarks . 62
References 64
6 Development of Surface Analytical Model for Accurate Hybrid
Freeform Surfaces . 65
6.1 Surface Generation for FTS/SSS Diamond Turning 66
6.1.1 Novel Surface Analytical Model . 66
6.1.2 Cutting Linearization Error . 68
6.2 Experimental Validation . 70
6.2.1 Evaluation of Critical Machining Parameters . 70
6.2.2 Cutting Experiments and Results . 77
6.3 Concluding Remarks . 80
References 81
7 Integration and Implementation 83
7.1 Integrated CAD/CAM System 83
7.1.1 Integrated Sub-system for AGMT Process . 84
7.1.2 Integrated Sub-system for Diamond Turning Process . 84
7.1.3 Optimization of Tool Geometry . 86
7.1.4 Geometrical Splitting of Hybrid Freeform Surface . 88
7.2 Case Study 1: Hexagonal Fresnel Lens Array Using AGMT
Process 89
7.2.1 Experimental Validations 89
7.3 Case Study 2: Multiple-Compound Eye Surface Design-B . 97
7.3.1 Experimental Validations 97
7.3.2 Cutting Experiments and Results . 102
7.4 Concluding Remarks . 104
References 105
8 Conclusions and Recommended Future Works 107
8.1 Major Contributions 107
8.2 Recommended Future Works . 108
Curriculum Vitae 111
xii ContentsAcronyms
AGMT Automated Guilloche machining technique
API Application programming interface
CAE Computer-aided engineering
FFT Fast Fourier transformation
FTS Fast tool servo
HCAA Hybrid constant-arc and constant-angle
HT Hilbert transformation
MLA Microlens array
NURBS Non-uniform rational B-splines
SAM Surface analytical model
SCD Single-crystal diamond
SSS Slow slide servo
SWG Sinusoidal wave grid
xiiiSymbols
r Outer radius of workpiece
fr Radial feed per radian
Nt Total number of spiral rotations to reach the center from the outer radius
q Radial position of the tool from the center of workpiece
h C-axis of spindle or angular position of a spiral point
x X-axis which controls the radial movement toward the spindle center and
is also perpendicular to spindle axis (Z-axis)
Z Z-axis which controls the axial movement along the spindle axis
W W-axis of the FTS stroke which controls the feed direction into the
workpiece surface and is parallel to Z-axis
i ith angular position of workpiece or spindle
W
max Maximum stroke zone of FTS
Δh Constant-angle
Np
Number of control points per rotation
Ez
Overcut depth of machined surface
b Surface slope along the feed direction
Pi* Exit/reentry point
rt Tool nose radius of diamond tool
W* Effective stroke length of FTS
Wc
Compensated FTS stroke length of tool trajectory
Zb
max Maximum Z-axis boundary
Zr Z-axis retraction
ZR
(Pi) Minimum value for intersection point of surface and cylindrical region within a circumscribed radius q(Pi)
Cx X-axis coordinates of the cutting point P in AGMT
Cy Y-axis coordinates of the cutting point P in AGMT
t Rotational position for the workpiece or spindle in AGMT
Xc X-axis of the center coordinates for an arc of the circular Fresnel lens in the
AGMT
xvYc Y-axis of the center coordinates for an arc of the circular Fresnel lens in the
AGMT
Ns
Number of sides in a polygon
P Cutting point or spiral point
rc
Arc-radius of circular tool trajectory of AGMT
rlens Lens radius of a microlens
rp
Radius of polygonal tool trajectory with respect to q
C Lens curvature of a microlens
T Remainder value of t divided by 360°
Tp
Angle between apothem of polygon and the Guilloche tool trajectory point
Dr Radii difference between the lens curvature rlens and tool nose radius rt
d Angular position of tool profiles with respect to the center of lens curvature
at point O in Fig. 5.6
Δd Angle between two tool profiles along radial feed direction in Fig. 5.6
Δd Distance AB in Fig. 5.6
ad Apothem of the triangle AOB in Fig. 5.6
af Apothem of hexagonal Fresnel lens
dd Euclidean distance from the midpoint of AB to the tip of cusp in Fig. 5.6
df
Relief depth of Fresnel zone plate
Δq Feed rate
Δqcr Critical feed rate
Eq
Cutting residual error
h
err Sagitta errors
htol Sagitta of the chord which represents the maximum permissible profile
error
S Arc-length from the center of the workpiece to a cutting point P
ΔS Constant-arc
St Arc-length for the entire spiral tool trajectory
ht Total angular of spiral rotations to reach the center from the outer radius
PV
err Peak-to-valley errors
d
err Local pverr
k Wavelength of SWG surface
/ Slope of tool trajectory in the cutting direction
∂Z
max Maximum deviation between two corresponding cutting points
ASWG Amplitude of SWG surface
PVtol Profile accuracy

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