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Step 16 Step 17 Step 18 Step 19 Step 20 If undercut is likely to occur (Pr(und) z 0.25) then jump to Step 20. Otherwise estimate the power ratio, PR, by using equation (3.10). Adjust the value of PR based on the restrictions of mode of metal transfer (see Figure 2.8). Set the PR limits as follow: Dip trans er: PRmrnl = 0.20 PR., = 0.40 S pray transfer: PRmin2 = 0.95 PR,,, 2 = 0.97 If PR indicates an excessively low voltage (PR < PR, 1, ) then make PR = PR, 1 If PR indicates excessive voltage in dip transfer (PR.,,,, < PR SO. 6) then make PR = PR,., If PR indicates globular to spray mode of metal transfer (0.6 < PR < PRmin2) then force spray transfer by making PR = PRmin2 If PR indicates excessive voltage in spray transfer (PR > PRm then make PR = PR,,,. Adjust the welding voltage by applying the corrected PR value to equation (3.14), which was obtained by rearranging the terms in equation (3.10). Vmean - PR (alo - + ß1oI, 2ea S10 Store in a list the current set of predicted welding parameters. (3.14) If welding speed, Sw , is smaller than its maximum allowable value, then increment its value by a fixed amount (e. g. 0.1 m/min) and return to Step 6. Otherwise proceed to Step 21. 75
Step 21 Step 22 If the wire feed speed, WFS , is smaller than its maximum allowable value, then increment its value by a fixed amount (e. g. 0. S m/min) and return to Step 5. Otherwise proceed to Step 22. Output the list of predicted sets of welding parameters in a growing order of possibility of defects being present, using as a sorting factor either Pr(arc), if GAP > 0, or Pr(und) otherwise. This algorithm was used to generate welding parameters for the welding trials. 3.3.2.2 Robot programming In the robot programming branch (dashed line in Figure 3.2), the weld joint positions are defined and the program extracts geometrical information about the joints. Two outputs can be obtained: a) the robot program (ASCII file), ready to be compiled, and b) a co-ordinates file, which can be used in an off-line programming software, such as Workspace to generate the robot program and to simulate it. The robot program is then translated to the specific binary code and downloaded to the robot controller for execution. The current implementation generates robot programs in ARLA (ABB Robot Language) and includes Workspace commands for simulation purposes and also commands for communicating with the control system. The off-line programming module assumes that the plane formed by the X and Y axes of the CAD world co-ordinates frame (WCF) is parallel to the robot installation floor and that the Z-axis points to the space above the floor in. a direction opposite to the gravitational force vector. The welded component should be designed in its final welded form as a continuous solid, using the solid modelling tools provided by AME (AutoCAD Modelling Extension), such that its orientation relative to the X- Y plane of the CAD WCF is as close as possible to its real orientation relative to the X-Y plane of the robot WCF (i. e. relative to the welding cell floor), since such orientation is used to extract information about the welding position and will affect the welding parameter generation. The origin of the CAD world co-ordinates frame is considered to be the origin of the workpiece co-ordinates frame in the real cell. The origin of the robot's world co-ordinates frame is assumed to coincide with the origin of the co-ordinates frame fixed at the robot basis. These considerations are easier to visualise by using graphical simulation of the robot workcell (see Figure 3.5). The weld joint is defined by the user by either selecting the corresponding edge in the solid model or by selecting the edge adjacent surfaces (see Figure 3.6), whose intersection forms the edge that corresponds to the weld joint. By using built- in AME AutoLISP® functions' different types of intersection curves and related information can be obtained, depending on the types of surfaces that form the intersection. In the current implementation, only linear intersection curves were 1A description of the AME AutoLISP functions and their sintax can be found in the AutoCAD Release 12 - AME 2.1 AutoLISP and API Manual. 76
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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
Page 49 and 50: Another type of robot static calibr
Page 51 and 52: spatter the gas nozzle is particula
Page 53 and 54: Table 2.1: Joint positioning tolera
Page 55 and 56: In order to minimise the undesirabl
Page 57 and 58: c) Ultrasonic sensors; d) Through-t
Page 59 and 60: where K,, K2, K3 and K4 are constan
Page 61 and 62: Philpott [refs. 21,131], based on t
Page 63 and 64: centre. This is attributed to the m
Page 65 and 66: technique must be employed to preve
Page 67 and 68: " digital hardware, which is basica
Page 69 and 70: " Maximum value, W.: Wmý = max(W )
Page 71 and 72: process studied over a small range.
Page 73 and 74: In-process welding control is a muc
Page 75 and 76: volume caused by the presence of a
Page 77 and 78: 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: Step 11 Step 12 Step 13 Step 14 Ste
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
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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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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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