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6. System Commissioning Trials This chapter presents the procedures adopted for commissioning the adaptive control system developed. It starts by showing the calibration procedures used for adapting the welding models developed by Ogunbiyi [ref. 51] to suit the differences in power sources and in jigging system. This includes the development of the stand-off estimation models, along with the aspects involved in the integration of the different parts of the system and the implementation and tuning of the process and stand-off controllers. 6.1 Calibration of the welding models In order to verify the validity of the previously established welding parameter prediction developed for a Migatronic BDH320 [ref. 51] when a different welding power source (BDH550) was used, initial flat position fillet welding trials were carried out. Appendix H shows the technical specifications of the two power sources. From the initial trials it was observed that the BDH550 produces a welding voltage lower than the set-up voltage. This resulted in very spattery welds and some very unstable situations. Previous work on the BDH320 showed no significant difference between the set-up voltage and the welding voltage. Table 6.1 shows the welding parameters used in the initial welding trials, along with the welding data collected during the same trials by using the monitoring hardware outlined in sections 5.3 and 5.4 and the monitoring software CranMon. The welding trials were carried out with the following fixed conditions: " Plate thickness: 3.2 mm " Length of weld: 232 mm " Welding speed: 0.5 m/min " Sampling rate: 5 kHz " Number of samples per data window: 512 " Time interval between windows 0.25 seconds Figure 6.1 shows the plot of the average welding voltage versus the set-up welding voltage. The equation shown in the chart and below gives the linear function that fits the data. y 0.9107"V., (6.1) The equation (6.1) was inverted and used to adjust the set-up voltage of the previous welding parameters (see Table 6.1) to the levels that supposedly would produce the required mean welding voltage. A new set of flat position fillet welding trials was carried out to observe the process behaviour with the adjusted set-up voltage. Table 6.2 shows the welding parameters used and the welding data collected. 127
Table 6.1 - Welding trials carried out with previously established welding parameters [ref. 511 In ut parameters Measured Res onse Run WFS SO Vt Vmean IfficaJ TSI TI DCI PR MCI 4 12 16.3 14.79 122.38 1.82 0.5 0.75 0.19 C2 6 12 17.6 15.61 166.02 2.15 0.55 0.69 0.22 C3 8 12 19.2 17.1 199.94 1.94 0.56 0.61 0.29 C4 10 12 20.7 18.39 219.18 2.14 0.49 0.58 0.31 C5 12 12 22.3 19.73 255.05 1.8 0.39 0.55 0.36 C6 14 12 23.9 21.33 265.38 1.89 0.47 0.5 0.37 C7 4 15 17.5 16.37 119.81 1.8 0.35 0.74 0.2 C8 6 15 18.2 16.61 160.25 1.76 0.44 0.69 0.24 C9 8 15 20.3 18.12 204.16 1.77 0.47 0.63 0.29 C10 10 15 21.8 19.46 232.26 1.92 0.44 0.59 0.33 C11 12 15 23.3 20.87 260.82 1.79 0.39 0.54 0.37 C14 4 20 19.6 18.52 111.54 2.36 0.29 0.58 0.33 4C15 6 20 21 19.5 152.49 1.98 0.31 0.64 0.29 C16 8 20 27.4 25.55 191.62 1.39 0.22 0.05 0.9 MC 17 10 20 28.4 26.34 216.15 1.22 0.14 0.04 0.94 MC IS 12 20 29.3 26.95 240.92 1.21 0.13 0.05 0.92 C19 14 20 30.2 27.68 263.39 1.23 0.11 0.06 0.91 WFS: wire feed speed [m/min] SO: stand-off [mm] Vut: set-up welding voltage [volts] V,.,: measured run average of welding voltage [volts] I ean: measured run average of welding current [Amps] TSI, TI, DCI, PR: measured run average of monitoring indices A considerable improvement has been observed with the adjusted set-up voltage. However, some of the conditions in dip transfer were still very spattery. A comparison between the levels of average. and maximum welding current produced by the BDH320 [ref. 51] and the BDH550, for the same welding parameters (V,.,, WFS, SO and Sw), reveals that the BDH550 delivers higher levels of average current (see Figure 6.2) and maximum current in the dip mode of metal transfer (see Figure 6.3). Since the level of spatter in the dip transfer mode is directly related to the maximum current reached during the short circuit (see section 2.1.5.2), the observed spatter levels could be explained by the higher current levels produced by the BDH550. In Figure 6.2, Imean_320 stands for the mean welding current produced by the BDH- 320, Imean_550 stands for the mean welding current produced by the BDH-550 and Ipred stands for the mean welding current predicted using the equation 3.1. In Figure 6.3, Imax_320 and Imax_550 stand for the maximum welding currents produced by the BDH-320 and BDH-550, respectively. 128
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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
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 and 130: Table 4.3 - Linguistic representati
Page 131 and 132: The introduction of such a reduced
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: 126
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
Page 181 and 182: 40 35 30 25 20 15 10 A+iIII+F0.17 2
Page 183 and 184: 30 28 26 24 22 SO_act [mm] DipR [mo
Page 185 and 186: 22 20 18 SO_act [mm] DipR [ohm/100]
Page 187 and 188: !: 30 25 20t 10 5-- 0 Dip Transfer
Page 189 and 190: 0.430- - 0.380- - :r 0.330 fPR L- 0
Page 191 and 192: 7.2 Tests with varying stand-off an
Page 193 and 194: Table 7.3 - Bead geometry along the
Page 195 and 196: ö a2 ., u" u,.., g .,. aucyuaac VI
Page 197 and 198: 0 24-- 22-- 18 210 1 90 0 v 170 mm
Page 199 and 200: Q 34 32 3o mIm Viewing direction Fl
Page 201 and 202: 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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