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Appendix D This Appendix shows a fibre optic based sensor concept for gap detection and seam tracking. Figure D. 1 shows the proposed concept. This was devised after analysing the currently available vision based seam trackers. These were observed to have the similarity of being directional, that is, they are only effective if the projected laser light precedes the welding torch during seam tracking. This restricts the welding torch to determined orientations, thus reducing the flexibility of the robot. Considering that the robot must change the orientation of the torch (rotation around the torch axis) in order to be able to reach certain positions in its workspace with a constant torch approach direction, a non-directional sensor would be needed. This could be obtained by rotating a directional sensor around the torch as needed or projecting an annular shaped laser light around the torch and sensing the intensity of the reflected laser light. The points with low intensity would correspond to the joint line or a gap, the number of low intensity points being an indication of the gap dimension. The exact position of these points in the circle could be known by using a coherent fibre bundle in the sensing ring. Some tests were carried out to check the viability of projecting a ring of laser using a series of optic fibres arranged in an annular shape. Although promising results were obtained, the development of this sensor was considered to be out of the scope of the thesis. 237
Water Cooling optic fibre bundle 0 Coherent annular shape optic fib re bundle HeNe Laser CCD Array Coherent optic fibre bundle Focusing lenses (annular shape) Annular shape laser projection Figure D. 1 - Fibre optic based sensor for seam tracking and gap detection 238
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CRANFIELD UNIVERSITY GC CARVALHO AN
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ABSTRACT The aim of this work was t
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I dedicate this work to the memory
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FIGURES TABLES APPENDICES NOTATION
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3.3.2.1 Welding parameters generato
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References Further reading Appendic
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Figure 3.12 Offsets for weld start
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Figure 6.31 Voltage step input test
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Figure J. 2 Plot of stand-off varia
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Table A. 1 Welding extended entity
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NOTATION A, Electrode sectional are
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Pr(ign) Possibility measure of proc
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1. Introduction Welding is the thir
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Chapter 4 describes the on-line pos
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In pulse transfer, the welding curr
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Pd = Pv - pzh-s (2.1) where Pd is t
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the bridge. Another factor that ind
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establish the stable conditions for
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Philpott [ref. 21] developed an on-
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current peak at the moment the tip
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obot on the line must be individual
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collision detection capabilities wh
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cause dynamic variation in the seam
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Another type of robot static calibr
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spatter the gas nozzle is particula
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Table 2.1: Joint positioning tolera
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In order to minimise the undesirabl
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c) Ultrasonic sensors; d) Through-t
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where K,, K2, K3 and K4 are constan
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Philpott [refs. 21,131], based on t
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centre. This is attributed to the m
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technique must be employed to preve
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" digital hardware, which is basica
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" Maximum value, W.: Wmý = max(W )
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process studied over a small range.
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In-process welding control is a muc
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volume caused by the presence of a
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SHIELDING GAS IN CONSUMABLE ELECTRO
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Arc voltage Anode Arc length I Anod
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computed ideal procedure optimisnti
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CONSTANT CURRENT POWER SOURCE `j' O
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Original Surface New Surface Electr
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otating welding wire direction weld
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3.1.1.1 Robot errors A robot arm is
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3.2.2 Programming error correction
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3.3.2 Off-line programming module I
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Pen is the weld penetration (side p
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a. 2) Geometrical constraints from
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Step 11 Step 12 Step 13 Step 14 Ste
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Step 21 Step 22 If the wire feed sp
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the Y'-axis results in a positive "
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_ p1e0a - pORoba m31 Ilp! - poll (3
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of a robot in its zero position12 w
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frame points to the front of the ro
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CAD Off-line (AutoCAD) programming
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Z Surface 4 A Y 7 M2 Open Edge Join
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WCF World Co-ordinates Frame 2a = J
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x Torch Co-ordinates Frame o Indica
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vo Ö 't7 Y7 't O m O 'S O O S O S
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ýý aý 0 oA aW ö A O Zt A OO 't
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Ti 9ý-! i4 *Tx t ap31 jx ý- ymin
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errors', (i. e. joint positioning,
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was considered to be outside the sc
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Table 4.3 - Linguistic representati
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The introduction of such a reduced
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Table 4.8 - Final welding process c
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the collection of welding data corr
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Step 4- Calculate the confidence of
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Z Table Co-ordinates Frame Y X Robo
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5.3 Monitoring system The monitorin
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the torch end. Only one degree of f
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Current: 500 Position: 234.5 5.7.3
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I" va JI ºr ö C 3 r" r" rl f_ £-
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IgurC a. H -I UI qur vCiSUJ JpCCU C
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126
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Table 6.1 - Welding trials carried
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Table 6.3 - Coefficients of Ogunbiy
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Note that the calibration model sho
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Table 6.6 - Welding parameters used
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constant set-up welding parameters
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stickout lengths and the temperatur
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of the dip mode of metal transfer.
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which would become active by settin
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In section 4.2.5 it has been mentio
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300 280 260 240 rd 35- 3D 25 20 15
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Figure 6.5 - Measured "versus" Pred
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i S 0 -0.1 -0.2 -0.3 -0.7- 68 10 12
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32.0 E 31.5 y 31.0 30.5 30.0 j 29.5
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35 - 30 p 15 10 0.00 2.60 5.42 8.23
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40 35 30 25 20 15 10 A+iIII+F0.17 2
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30 28 26 24 22 SO_act [mm] DipR [mo
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22 20 18 SO_act [mm] DipR [ohm/100]
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!: 30 25 20t 10 5-- 0 Dip Transfer
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0.430- - 0.380- - :r 0.330 fPR L- 0
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7.2 Tests with varying stand-off an
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Table 7.3 - Bead geometry along the
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ö a2 ., u" u,.., g .,. aucyuaac VI
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0 24-- 22-- 18 210 1 90 0 v 170 mm
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Q 34 32 3o mIm Viewing direction Fl
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ýa 34 mm JO a .. ý nn ýr "u 00 M
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22 20 18 Viewing direction Flange W
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36 33 31 o 29 t 350 310 o 290 U due
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I C, x -i 23 21 j 19 Q 240c WFS =10
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en 34 32 - vsec 30- 26- 24 + .. ++
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Page 213 and 214: " to design and build the hardware
Page 215 and 216: Although only linear joints were im
Page 217 and 218: for predicting possibility of bad a
Page 219 and 220: 8.4 Process monitoring and control
Page 221 and 222: satisfy the required quality criter
Page 223 and 224: 198
Page 225 and 226: types of joints and multi-pass weld
Page 227 and 228: [14] NEMCHINSKY, V. A. The effect o
Page 229 and 230: [38] D1LTHEY, U. , REICHELL, T. , S
Page 231 and 232: [64] KING, F-J. and HIRSCH, P. Seam
Page 233 and 234: [86] CARGNELLI, M. and ROGOWSKI, A.
Page 235 and 236: [109] KURKIN, N. S. and DRIKKER, V.
Page 237 and 238: [130] USHIO, M. , LIU, W. , MAO, W.
Page 239 and 240: [151] DAVIS, A. R. Orr-line gap det
Page 241 and 242: [177] COOK, G. E. Feedback and adap
Page 243 and 244: [201] WON, Y. J. and CHO, H. S. A f
Page 245 and 246: 220
Page 247 and 248: 222
Page 249 and 250: wnum: local variable which defines
Page 251 and 252: Table A. 1 - continuation List item
Page 253 and 254: Imean = a2 + b2*WFS + c2*SO + d2*SO
Page 255 and 256: TCP2 number are also defined. The o
Page 257 and 258: f ROBSET. DAT: This file is created
Page 259 and 260: Figure C. 3 - Main dialogue box of
Page 261: Choose the set of welding parameter
Page 265 and 266: Figure E. 1 - Main graphical screen
Page 267 and 268: 242
Page 269 and 270: Table G. 2 - Interface box external
Page 271 and 272: Robot ii Controller +24W CO . +24Vd
Page 273 and 274: 248
Page 275 and 276: Table 1.1 - continuation Run Vpk M
Page 277 and 278: 10- y =0.001ac 0 r. dSO [mm] $0 '10
Page 279 and 280: 5.00- 0.00 y=0.0019x 1000 1500 2000
Page 281 and 282: Table J. 7 - Welding data collected
Page 283 and 284: Table J. 10 - Welding data collecte
Page 287 and 288: 20.00- 15. M y=0.0047x - 1.7922 10.
Page 291 and 292: 266
Page 293 and 294: Table K. 1- continuation Set-up par
Page 295 and 296: Table K. 1 - continuation Set-up pa
Page 297 and 298: Table K. 2 - continuation Set up pa
Page 299 and 300: Table K. 2 - Continuation Set-up pa
Page 301 and 302: Table K. 3 - Continuation Set-up pa
Page 303: Table K. 3 - Continuation Setup par
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