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Table 4.4 - Control rules based on Power Ratio with reduced range for dip transfer 1 If PR < PRLOWDIP then process is unstable . DV = +BIGTRIM 2 If PRLOWDIP 5 PR < minPRdip then process slightly tending to instability AV = MICROTRIM 3 If minPRdip
The introduction of such a reduced range of variation (rules 2 to 4 in Table 4.4) improved the controller behaviour. However, it still resulted in excessive spatter for low wire feed speeds and in a slightly oscillatory behaviour. In order to improve the controller performance further, additional rules based on the other monitoring indices3 were introduced. The rules were developed from the observation of the behaviour of these indices during controlled trials carried out with the control rules shown in Table 4.4. It was observed that the indices would vary with different sensitivities as a response to instabilities in the process. Based on this observation, - a set of interdependent rules were generated and logically organised so that the less sensitive indices would be tested before the most sensitive ones. The rules were introduced under rule number 3 in Table 4.4 and are shown in Table 4.7. Note that the amount of voltage correction used in rules 2 and 4 of Table 4.4 was increased. Table 4.6 shows the linguistic representation of the limits of DCI, TI and TSI used for fine-tuning the stability in dip transfer. Table 4.6 - Linguistic representation of limits for DCI, TI and TSI in dip transfer DCI-LOW = 0.4 DCI-HIGH - 0.8 TI-LOW = 0.3 TI-HIGH - 0.45 TSI-LOW = 1.6 TSI HIGH -1. Q Table 4.7 - Control rules based on DCI, TI and TSI 2 If PRLOWDIP 5 PR < minPRdip then process slightly tending to instability AV = SMALLTRIM 3 IfminPRdi 5 PR :5 maxPRdip then test DCI 3. a If DCI < DCI-LOW then decrease the voltage slightly AV = -MICROTRIM else if DCI > DCI-HIGH then increase the voltage slightly AV = MICROTRIM else test TI 3. b IfTI > TI-HIGH then increase the voltage slightly 3. c AV = MICROTRIM else if TI < TI-LOW then decrease the voltage slightly AV = -MICROTRIM else test TSI IfTSI > TSI-HIGH or TSI < TSI-LOW then reduce the voltage slightly AV = -MICROTRIM else the process is stable AV = ZEROTRIM 4 IfmaxPRdip < PR < PRHIGHDIP then process slightly tending to instability AV = -MICROTRIM 2 Excessive spatter in this context does not imply that the process is unstable. It just implies that = better stability state can still be achieved. generating less and finer spatter. Dip Consistency Index (DCI), Transfer Index (TI) and Transfer Stability Index (TSI) 106
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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
Page 79 and 80: Arc voltage Anode Arc length I Anod
Page 81 and 82: computed ideal procedure optimisnti
Page 83 and 84: CONSTANT CURRENT POWER SOURCE `j' O
Page 85 and 86: Original Surface New Surface Electr
Page 87 and 88: otating welding wire direction weld
Page 89 and 90: 3.1.1.1 Robot errors A robot arm is
Page 91 and 92: 3.2.2 Programming error correction
Page 93 and 94: 3.3.2 Off-line programming module I
Page 95 and 96: Pen is the weld penetration (side p
Page 97 and 98: a. 2) Geometrical constraints from
Page 99 and 100: Step 11 Step 12 Step 13 Step 14 Ste
Page 101 and 102: Step 21 Step 22 If the wire feed sp
Page 103 and 104: the Y'-axis results in a positive "
Page 105 and 106: _ p1e0a - pORoba m31 Ilp! - poll (3
Page 107 and 108: of a robot in its zero position12 w
Page 109 and 110: frame points to the front of the ro
Page 111 and 112: CAD Off-line (AutoCAD) programming
Page 113 and 114: Z Surface 4 A Y 7 M2 Open Edge Join
Page 115 and 116: WCF World Co-ordinates Frame 2a = J
Page 117 and 118: x Torch Co-ordinates Frame o Indica
Page 119 and 120: vo Ö 't7 Y7 't O m O 'S O O S O S
Page 121 and 122: ýý aý 0 oA aW ö A O Zt A OO 't
Page 123 and 124: Ti 9ý-! i4 *Tx t ap31 jx ý- ymin
Page 125 and 126: errors', (i. e. joint positioning,
Page 127 and 128: was considered to be outside the sc
Page 129: Table 4.3 - Linguistic representati
Page 133 and 134: Table 4.8 - Final welding process c
Page 135 and 136: the collection of welding data corr
Page 137 and 138: Step 4- Calculate the confidence of
Page 139 and 140: Z Table Co-ordinates Frame Y X Robo
Page 141 and 142: 5.3 Monitoring system The monitorin
Page 143 and 144: the torch end. Only one degree of f
Page 145 and 146: Current: 500 Position: 234.5 5.7.3
Page 147 and 148: I" va JI ºr ö C 3 r" r" rl f_ £-
Page 149 and 150: IgurC a. H -I UI qur vCiSUJ JpCCU C
Page 151 and 152: 126
Page 153 and 154: Table 6.1 - Welding trials carried
Page 155 and 156: Table 6.3 - Coefficients of Ogunbiy
Page 157 and 158: Note that the calibration model sho
Page 159 and 160: Table 6.6 - Welding parameters used
Page 161 and 162: constant set-up welding parameters
Page 163 and 164: stickout lengths and the temperatur
Page 165 and 166: of the dip mode of metal transfer.
Page 167 and 168: which would become active by settin
Page 169 and 170: In section 4.2.5 it has been mentio
Page 171 and 172: 300 280 260 240 rd 35- 3D 25 20 15
Page 173 and 174: Figure 6.5 - Measured "versus" Pred
Page 175 and 176: i S 0 -0.1 -0.2 -0.3 -0.7- 68 10 12
Page 177 and 178: 32.0 E 31.5 y 31.0 30.5 30.0 j 29.5
Page 179 and 180: 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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186
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" to design and build the hardware
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Although only linear joints were im
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for predicting possibility of bad a
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8.4 Process monitoring and control
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satisfy the required quality criter
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198
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types of joints and multi-pass weld
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[14] NEMCHINSKY, V. A. The effect o
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[38] D1LTHEY, U. , REICHELL, T. , S
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[64] KING, F-J. and HIRSCH, P. Seam
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[86] CARGNELLI, M. and ROGOWSKI, A.
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[109] KURKIN, N. S. and DRIKKER, V.
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[130] USHIO, M. , LIU, W. , MAO, W.
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[151] DAVIS, A. R. Orr-line gap det
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[177] COOK, G. E. Feedback and adap
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[201] WON, Y. J. and CHO, H. S. A f
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220
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222
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wnum: local variable which defines
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Table A. 1 - continuation List item
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Imean = a2 + b2*WFS + c2*SO + d2*SO
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TCP2 number are also defined. The o
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f ROBSET. DAT: This file is created
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Figure C. 3 - Main dialogue box of
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Choose the set of welding parameter
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Water Cooling optic fibre bundle 0
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Figure E. 1 - Main graphical screen
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242
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Table G. 2 - Interface box external
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Robot ii Controller +24W CO . +24Vd
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248
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Table 1.1 - continuation Run Vpk M
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10- y =0.001ac 0 r. dSO [mm] $0 '10
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5.00- 0.00 y=0.0019x 1000 1500 2000
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Table J. 7 - Welding data collected
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Table J. 10 - Welding data collecte
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20.00- 15. M y=0.0047x - 1.7922 10.
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266
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Table K. 1- continuation Set-up par
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Table K. 1 - continuation Set-up pa
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Table K. 2 - continuation Set up pa
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Table K. 2 - Continuation Set-up pa
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Table K. 3 - Continuation Set-up pa
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Table K. 3 - Continuation Setup par
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