ComputerAided_Design_Engineering_amp_Manufactur.pdf

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FIGURE 2.7 For each batch of nodes to be machined, two NC programs are required: one for the CNC of the machining center and one for the CNC of the rotary table. To produce consistent and reliable NC programs quickly without specially employing a process planner/NC programmer, a PC-based, computerautomated process planning system has been developed to directly translate the aforementioned geometric data from the computer-aided, space-frame design software to NC programs for the two controllers, without intervention by the operator. The PC-based system is also connected by serial communication lines to the two CNC systems for direct transfer of the NC programs. An important consideration in developing a suitable process plan for the machining of the space-frame nodes is the setup planning, in which the CAD-referenced hole configuration is transformed to a mountinghole-referenced configuration that minimizes the required number of mounting holes and setups. The determination of the optimal mounting-hole-referenced configuration is detailed in Reference 10. Based on the mounting-hole-referenced hole configuration, NC programs are automatically generated for the following sequence of operations: • Machining of the node in the fixed fixture • Machining of the node mounted on the rotary table Two machine-referenced coordinate systems (G54 and G55 in word address format for the FANUC CNC system) are set during the machining of the nodes. One is set with reference to the node in the fixed © 2001 by CRC Press LLC Space frame nodes.
FIGURE 2.8 fixture for the machining of the first mounting hole as well as the node code and the reference mark engraving. The other is set with reference to the node mounted on the rotary table. During the generation of the NC programs, necessary information, such as machinability data, tool-change codes, offset codes, etc., is automatically extracted from a data base that can be accessed and modified by authorized personnel with a given password. The NC program begins with commands to the CNC machining center and rotary table for the machining of the first mounting hole in the node mounted in the fixed fixture. In addition, a node code of the node (e.g., T1 for the hole configuration shown in Table 2.1) is engraved on the flat of the mounting hole. If the mounting hole is a reference hole, a reference mark is also engraved on the flat. Both the node code and the reference mark are used in the assembly of the space frame. Once the mounting hole requirement has been determined, the orientation of every hole to be machined with respect to the mounting hole is appropriately transformed. If two mounting holes are required, two sets of hole configuration will be defined, appropriately transformed to the reference system based on each mounting hole. Figure 2.9 lists a s<strong>amp</strong>le section of an NC program for the machining center. The first section of the program includes NC instructions for the machining of the mounting holes. The corresponding NC program for the rotary table to rotate (in two axes) the holes to the correct vertical orientation for the drilling of the holes is partially listed in Figure 2.10. 2.3 Curve Fitting for NC Machining In general, current CNC machines are capable only of linear and circular interpolations. General curves to be produced by CNC have to be approximated by fitting with lines, circular arcs, or a combination of both, to some given tolerance. 14–23 The aim is to obtain the least number of linear or circular segments required to approximate the curve to reduce the length of the NC program and the time to produce the approximate curve. Piecewise fitting using linear segments is very commonly used and reported, 24–28 as this approach is simplest to implement and fastest to compute. The resultant surface finish is, however, poor because of discontinuities between the piecewise-fitted segments. Linear approximation also tends to require a significantly larger number of segments than circular-arc approximation, unless the curvature of the curve to be fitted is small. 29,30 The circular-arc approximation may be applied in a piecewise manner to a predetermined set of points whereby the deviation of the arc from the points that it serves to replace © 2001 by CRC Press LLC Machining center for machining of space frame nodes.
Page 1 and 2: COMPUTER-AIDED DESIGN, ENGINEERING,
Page 3 and 4: Library of Congress Cataloging-in-P
Page 5 and 6: Editor Cornelius T. Leondes, B.S.,
Page 7 and 8: Chapter 1 Chapter 2 Chapter 3 Chapt
Page 9 and 10: the implementation of the IPD syste
Page 11 and 12: In our IPD system implementations,
Page 13 and 14: 2. Specification of analysis-specif
Page 15 and 16: FIGURE 1.2 base or the design insta
Page 17 and 18: FIGURE 1.4 System architecture of t
Page 19 and 20: of a beam is considered for FEA. Th
Page 21 and 22: FIGURE 1.7 through the control expe
Page 23 and 24: 2. machining facility (e.g., gang m
Page 25 and 26: from the FBDS. The user also specif
Page 27 and 28: Depending on the type of feature to
Page 29 and 30: TABLE 1.6 Tolerance synthesis is de
Page 31 and 32: FIGURE 1.12 Display of the NC tool
Page 33 and 34: component geometric entities and va
Page 35 and 36: FIGURE 1.14 The system architecture
Page 37 and 38: TABLE 1.10 User Input for the Toler
Page 39 and 40: TABLE 1.11 Tolerance Specifications
Page 41 and 42: 7. Z. Young and I. R. Groose. A rul
Page 43 and 44: FIGURE 2.1 Tool paths generated for
Page 45 and 46: FIGURE 2.2 sented by instances of f
Page 47 and 48: TABLE 2.1 A CAD-Generated Hole Conf
Page 49: FIGURE 2.6 mounted on the rotary ta
Page 53 and 54: FIGURE 2.10 or best-fit, or the cur
Page 55 and 56: FIGURE 2.11 Linear approximation of
Page 57 and 58: FIGURE 2.13 Circular approximation
Page 59 and 60: FIGURE 2.14(b) Circular approximati
Page 61 and 62: FIGURE 2.16 Types of biarcs. FIGURE
Page 63 and 64: FIGURE 2.18 Approximation of scanne
Page 65 and 66: FIGURE 2.20 A touch trigger probe c
Page 67 and 68: TABLE 2.4 Substitute Elements in CM
Page 69 and 70: FIGURE 2.21 CMM planning requiremen
Page 71 and 72: Product Model Representation for Co
Page 73 and 74: © 2001 by CRC Press LLC TABLE 2.5
Page 75 and 76: TABLE 2.7 Partial Listing of Dimens
Page 77 and 78: 24. Makinouchi, S., Okamoto, M., an
Page 79 and 80: Bijan Shirinzadeh Monash University
Page 81 and 82: FIGURE 3.1 Trends in flexible manuf
Page 83 and 84: FIGURE 3.3 and constrain different
Page 85 and 86: Other Fixturing Techniques There ar
Page 87 and 88: FIGURE 3.6 contact point. The geome
Page 89 and 90: FIGURE 3.8 The vertical support fix
Page 91 and 92: and moments about the contact point
Page 93 and 94: een identified, the normals are use
Page 95 and 96: one of choosing the variables: such
Page 97 and 98: Fixture Module Location An importan
Page 99 and 100: FIGURE 3.15 Illustration of functio
Page 101 and 102:
FIGURE 3.18 Minimum separation test
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direction) the face, respectively.
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FIGURE 3.21 Software structure for
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3.8 Conclusion A reconfigurable fix
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Heui Jae Pahk Seoul National Univer
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FIGURE 4.1(b) Conceptual framework
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4.3 Measurement Points Sampling and
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Surface S2 Measurement Path FIGURE
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FIGURE 4.4 Rough phase alignment ba
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deviation between the nominal CAD d
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FIGURE 4.6(a) Sum of squares distan
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FIGURE 4.7(c) Trailing edge. (c) th
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FIGURE 4.8(a) Profile tolerance of
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The calculated minimum form error i
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FIGURE 4.11(a) A typical mold havin
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FIGURE 4.11(d) Inspection results f
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FIGURE 4.12(c) Maximum deviation (p
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5.1 Introduction Developments in th
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process plan for a part (Figure 5.3
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FIGURE 5.5 leading to the developme
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the previously stored process plan
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FIGURE 5.7 Techniques of defining a
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Feature Recognition and Extraction
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in relation to another feature (e.g
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FIGURE 5.9 Framework for building a
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FIGURE 5.10 Process plan content.
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FIGURE 5.12 Schematic sketch of the
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Several techniques of defining a fe
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TABLE 5.1 Data Structure for Repres
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FIGURE 5.16 Classification of the t
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system to ensure that the part bein
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FIGURE 5.19 Graphical model of the
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TABLE 5.4 Data Structure for Repres
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FIGURE 5.20 Mapping between machini
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algorithms. (Some details of the pr
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FIGURE 5.24 An example rotational p
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FIGURE 5.26 Down_face-turn-up_face
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FIGURE 5.27 Procedure for machine t
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FIGURE 5.28 Determining the number
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DL is needed to be set only if the
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FIGURE 5.31 Operation sequencing co
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Cutting Tool Selection Selection of
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1. A tool is searched for in the da
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FIGURE 5.32 Inputs to optimization
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When these values are substituted,
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Usually, maximum and minimum speed
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FIGURE 5.33 Solution methodology.
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TABLE 5.6 Process Plan Internal Rep
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In a strict theoretical perspective
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18. Domazet, D. S. and Lu, S. C. Y,
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63. Prasad, A. V. S. R. K., Rao, P.
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CAD systems. The sample consists of
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learn to master the new system. An
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Although researchers appear to agre
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Link and Zmud28 found that organic
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Informal Training Informal CAD trai
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informal training programs, felt th
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6. C. A. Beatty, Tall Tales and Rea
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A.Y.C. Nee National University of S
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FIGURE 7.1 Planning, design, and ma
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A metal stamping can have the follo
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FIGURE 7.3 Strips used to notch out
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A Skeletal Approach for the Recogni
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These findings can be used to devel
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Semi-Direct Piloting In cases where
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a larger value, the die operations
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FIGURE 7.9 Symbolic relationship be
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FIGURE 7.11 The shape of the envelo
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TABLE 7.1 Schema for the Generation
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strong reasons to support a move to
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FIGURE 7.16 3-D CAD model of a part
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References Cheok, B.T. et al. (1994
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include the once forbidden generati
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A temporal matrix (T-Matrix) is pro
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FIGURE 8.1 A basic process. (From R
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FIGURE 8.4(a) Generate a new IG usi
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Note if the pair of nodes are both
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TABLE 8.1 Summary of the Rules Cond
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The correctness of these rules is e
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needs to show that after each full
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ule is violated, a warning should b
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Π1 Π3 Π4 FIGURE 8.8(a) After add
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
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A ik � ‘U’ and is in a cycle
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FIGURE 8.12(a) Add [p2 t7 p7 t8 p4]
Page 271 and 272:
FIGURE 8.12(c) Add a token to p8 vi
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FIGURE 8.12(e) Add [p8 t9 p14 t10 p
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FIGURE 8.13 An example of rule TT.0
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FIGURE 8.14 A GPN model of a machin
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FIGURE 8.15(b) The first exclusive
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FIGURE 8.15(d) The last exclusive T
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FIGURE 8.15(f) After entering the a
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FIGURE 8.15(h) Completion of Compon
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FIGURE 8.15(j) Two PP-generations:
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FIGURE 8.15(l) The last exclusive T
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t1 t5 p1 p5 t6 (a) t2 t3 t4 2 2 p2
Page 293 and 294:
FIGURE 8.17 An example of partial f
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Theorem 10: If pi → pk in a synth
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Note that control transitions are o
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t j than the lower at , it indicate
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• Programming logic and VLSI arra
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7. Chao, D. Y. and D. T. Wang, Appl
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53. Villaroel, J. L., J. Martinez,
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q u : the numerator of the least ra
Page 309 and 310:
geometric modeling, engineering ana
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In dimension driven or parametric d
Page 313 and 314:
FIGURE 9.3 configuration of bodies
Page 315 and 316:
FIGURE 9.6 FIGURE 9.7 Geometric Int
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FIGURE 9.8 Intersection of degrees
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will introduce a way to propagate p
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Completeness of Dimensions Complete
Page 323 and 324:
FIGURE 9.12 3-D constraints. © 200
Page 325 and 326:
The distance constraint from pt �
Page 327 and 328:
therefore: Now merge the lists and
Page 329 and 330:
Quantity analysis methods have the
Page 331 and 332:
y a revolute joint. By selecting al
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