ComputerAided_Design_Engineering_amp_Manufactur.pdf

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standard punch shapes offered in the Face ’88–’89 catalogue. They are • Number of real links (RLs) • Number of virtual links (VLs) • Number of open nodes in the simplified skeleton (ONs) • Real links orthogonal to each other? (OR?) • Real links symmetrical about shape center? (SY?) • Number of extension links (ELs) • Number of vertices among all extension links with non-zero shrinkage grade (EFs) Of these features, RLs, VLs, ONs, ELs, and EFs are derived directly from the ESL skeletal data. OR? and SY? are topological descriptors of the ESL skeleton and require additional processing for their derivation. On further analysis, the following findings are noted: 1. All the standard punch shapes have five or fewer real links. In other words, contours with 5 or more real links can be immediately classified as non-standard. 2. More than half of these standard shapes can be distinguished by considering only four of these features, namely, RLs, VLs, ELs, and EFs. 3. The rest can be distinguished using all seven features, except for seven pairs of shapes that have identical skeletal features but differ in minute dimensional or topological details. 4. For these seven pairs, additional conditions must be fulfilled before such contours can be positively identified. The confirmation checks to distinguish between two sets of standard shapes that share identical skeletal features are explained in Figure 7.6. FIGURE 7.6 Additional confirmation checks required to distinguish between two standard shapes having similar ESL skeletal features.
These findings can be used to develop a hierarchical search method which attempts to use the least features (and hence least computer resources) to classify a shape. If a decision cannot be made, it will move to the next level of search where more skeletal features of the input contour need to be extracted and matched. At the end of the search, a contour will be classified as a standard punch shape or as nonstandard if it fails all the tests. The algorithm for the hierarchical search method used to match an input contour with standard shapes provided by the Face ‘88–‘89 Catalogue is shown as a flowchart in Figure 7.7. Once a contour is recognized as a standard shape, the skeletal data can be used to calculate its principal dimensions. The ESL skeleton and the seven features are independent of contour scale, position, and orientation. This approach therefore offers an efficient and complete solution to the task of recognizing a bounded set of standard shapes. In addition, the skeletal approach would help simplify the task of decomposing complicated non-standard punch profiles into smaller, standard/non-standard punch shapes because every real link essentially represents a trapezoidal region. By removing a real link, we are effectively decomposing the affected profile into a simpler shape and a trapezoidal contour. 7.6 Some Rules for Operations Planning Before the strip layout can be developed, the die maker must decide on the piloting scheme and the carrier scheme to guide and carry the strip as it progresses through the die. Piloting Schemes Pilots are used to guide a strip into position before the die operations at a station are executed. Four different piloting schemes are used in progressive dies. The rules for the selection of piloting holes under the various schemes are described below. Direct Piloting Direct piloting consists of piloting in holes pierced in the workpiece at an earlier station. This is the preferred piloting scheme as it is most economical in terms of die construction and strip material usage. Pilot holes are always pierced first and should be made available at every station up to the last (or nextto-last) station. Because of the continuous insertion and removal of the pilot, there is a tendency for the shape of the hole to be distorted. Hence, the following conditions must be satisfied before a hole on the workpiece can be selected for use as a pilot hole: 1. It is circular in shape. 2. The specified tolerance is not high. 3. It is big enough for use as a pilot hole. 4. It does not lie on the folded portion of the workpiece. 5. It is not too close to the edge of the workpiece. 6. It is not too close to another hole on the workpiece. From the list of holes that satisfy the above conditions, the most suitable pilot holes are selected based on the following priority: 1. If only one hole is available, it will be selected in the first instance. 2. If there are a number of holes, select the two largest holes (which are equal in diameter); the distance between them in the direction perpendicular to the feed direction must be greater than a minimum preset distance. The holes must be located on opposite sides of the part. 3. Select the two largest holes (the diameters of which are within a preset percentage of each other) that satisfy the earlier conditions. 4. Select the hole that is nearest to the centroid of the unfolded portion of the workpiece.
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COMPUTER-AIDED DESIGN, ENGINEERING,
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Library of Congress Cataloging-in-P
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Editor Cornelius T. Leondes, B.S.,
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Chapter 1 Chapter 2 Chapter 3 Chapt
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the implementation of the IPD syste
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In our IPD system implementations,
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2. Specification of analysis-specif
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FIGURE 1.2 base or the design insta
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FIGURE 1.4 System architecture of t
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of a beam is considered for FEA. Th
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FIGURE 1.7 through the control expe
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2. machining facility (e.g., gang m
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from the FBDS. The user also specif
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Depending on the type of feature to
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TABLE 1.6 Tolerance synthesis is de
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FIGURE 1.12 Display of the NC tool
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component geometric entities and va
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FIGURE 1.14 The system architecture
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TABLE 1.10 User Input for the Toler
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TABLE 1.11 Tolerance Specifications
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7. Z. Young and I. R. Groose. A rul
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FIGURE 2.1 Tool paths generated for
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FIGURE 2.2 sented by instances of f
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TABLE 2.1 A CAD-Generated Hole Conf
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FIGURE 2.6 mounted on the rotary ta
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FIGURE 2.8 fixture for the machinin
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FIGURE 2.10 or best-fit, or the cur
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FIGURE 2.11 Linear approximation of
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FIGURE 2.13 Circular approximation
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FIGURE 2.14(b) Circular approximati
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FIGURE 2.16 Types of biarcs. FIGURE
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FIGURE 2.18 Approximation of scanne
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FIGURE 2.20 A touch trigger probe c
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TABLE 2.4 Substitute Elements in CM
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FIGURE 2.21 CMM planning requiremen
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Product Model Representation for Co
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© 2001 by CRC Press LLC TABLE 2.5
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TABLE 2.7 Partial Listing of Dimens
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24. Makinouchi, S., Okamoto, M., an
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Bijan Shirinzadeh Monash University
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FIGURE 3.1 Trends in flexible manuf
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FIGURE 3.3 and constrain different
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Other Fixturing Techniques There ar
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FIGURE 3.6 contact point. The geome
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FIGURE 3.8 The vertical support fix
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and moments about the contact point
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een identified, the normals are use
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one of choosing the variables: such
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Fixture Module Location An importan
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FIGURE 3.15 Illustration of functio
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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
Page 175 and 176: FIGURE 5.27 Procedure for machine t
Page 177 and 178: FIGURE 5.28 Determining the number
Page 179 and 180: DL is needed to be set only if the
Page 181 and 182: FIGURE 5.31 Operation sequencing co
Page 183 and 184: Cutting Tool Selection Selection of
Page 185 and 186: 1. A tool is searched for in the da
Page 187 and 188: FIGURE 5.32 Inputs to optimization
Page 189 and 190: When these values are substituted,
Page 191 and 192: Usually, maximum and minimum speed
Page 193 and 194: FIGURE 5.33 Solution methodology.
Page 195 and 196: TABLE 5.6 Process Plan Internal Rep
Page 197 and 198: In a strict theoretical perspective
Page 199 and 200: 18. Domazet, D. S. and Lu, S. C. Y,
Page 201 and 202: 63. Prasad, A. V. S. R. K., Rao, P.
Page 203 and 204: CAD systems. The sample consists of
Page 205 and 206: learn to master the new system. An
Page 207 and 208: Although researchers appear to agre
Page 209 and 210: Link and Zmud28 found that organic
Page 211 and 212: Informal Training Informal CAD trai
Page 213 and 214: informal training programs, felt th
Page 215 and 216: 6. C. A. Beatty, Tall Tales and Rea
Page 217 and 218: A.Y.C. Nee National University of S
Page 219 and 220: FIGURE 7.1 Planning, design, and ma
Page 221 and 222: A metal stamping can have the follo
Page 223 and 224: FIGURE 7.3 Strips used to notch out
Page 225: A Skeletal Approach for the Recogni
Page 229 and 230: Semi-Direct Piloting In cases where
Page 231 and 232: a larger value, the die operations
Page 233 and 234: FIGURE 7.9 Symbolic relationship be
Page 235 and 236: FIGURE 7.11 The shape of the envelo
Page 237 and 238: TABLE 7.1 Schema for the Generation
Page 239 and 240: strong reasons to support a move to
Page 241 and 242: FIGURE 7.16 3-D CAD model of a part
Page 243 and 244: References Cheok, B.T. et al. (1994
Page 245 and 246: include the once forbidden generati
Page 247 and 248: A temporal matrix (T-Matrix) is pro
Page 249 and 250: FIGURE 8.1 A basic process. (From R
Page 251 and 252: FIGURE 8.4(a) Generate a new IG usi
Page 253 and 254: Note if the pair of nodes are both
Page 255 and 256: TABLE 8.1 Summary of the Rules Cond
Page 257 and 258: The correctness of these rules is e
Page 259 and 260: needs to show that after each full
Page 261 and 262: ule is violated, a warning should b
Page 263 and 264: Π1 Π3 Π4 FIGURE 8.8(a) After add
Page 265 and 266: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Page 267 and 268: A ik � ‘U’ and is in a cycle
Page 269 and 270: FIGURE 8.12(a) Add [p2 t7 p7 t8 p4]
Page 271 and 272: FIGURE 8.12(c) Add a token to p8 vi
Page 273 and 274: FIGURE 8.12(e) Add [p8 t9 p14 t10 p
Page 275 and 276: 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
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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
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geometric modeling, engineering ana
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In dimension driven or parametric d
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FIGURE 9.3 configuration of bodies
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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
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FIGURE 9.12 3-D constraints. © 200
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The distance constraint from pt �
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therefore: Now merge the lists and
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Quantity analysis methods have the
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y a revolute joint. By selecting al
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