AWS WHC1 11-2001 Mechanized Automated and Robotic Welding.pdf

1、AWS Resourcesfor EngineersMechanized,Automated, andRobotic Weldingwelding know-how for engineersii 2001 by American Welding SocietyAll rights reservedNo portion of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by anymeans, including mechanical, photocopying

2、, recording, or otherwise, without the prior written permission of thecopyright owner.Authorization to photocopy items for internal, personal, or educational classroom use only, or the internal,personal, or educational classroom use only of specific clients, is granted by the American Welding Societ

3、y (AWS)provided the appropriate fee is paid to the Copyright Clearance Center, 222 Rosewood Drive, Danvers, MA01923; telephone: (978) 750-8400; Internet: .The Welding Handbook is the result of the collective effort of many volunteer technical specialists who provideinformation to assist with the des

4、ign and application of welding and allied processes.The information and data presented in the Welding Handbook, and this chapter, are intended for informationalpurposes only. Reasonable care is exercised in the compilation and publication of the Welding Handbook to ensurethe authenticity of the cont

5、ents. However, no representation is made as to the accuracy, reliability, or completenessof this information, and an independent, substantiating investigation of the information should be undertaken bythe user.The information contained in the Welding Handbook shall not be construed as a grant of any

6、 right of manufac-ture, sale, use, or reproduction in connection with any method, process, apparatus, product, composition, or sys-tem, which is covered by patent, copyright, or trademark. Also, it shall not be construed as a defense against anyliability for such infringement. Whether the use of any

7、 information in the Welding Handbook would result in aninfringement of any patent, copyright, or trademark is a determination to be made by the user.Printed in the United States of AmericaiiiACKNOWLEDGMENTSThis chapter from the Welding Handbook, Ninth Edition, Volumn 1, “Welding Science and Technolo

8、gy,” has beenselected by the AWS Product Development Committee as a service to industry professionals.The Welding Handbook Committee and the editors recognize the contributions of the volunteers who have cre-ated, developed, and documented the technology of welding and shared it in the past editions

9、 of the WeldingHandbook. The same enthusiasm, dedication, and willingness to share that they made a tradition continue withthis ninth edition of the Welding Handbook.The Welding Handbook Committee and the editors extend appreciation to the AWS technical committees whodeveloped the current consensus

10、standards that pertain to this volume. They are also grateful to L. P. Connor,editor of Volume 1, eighth edition, and the members of the AWS technical staff for the engineering assistance theygenerously contributed.ivCONTRIBUTORSWELDING HANDBOOK COMMITTEEH. R. Castner, Chair Edison Welding Institute

11、B. J. Bastian, First Vice-Chair Benmar AssociatesR. S. Funderburk The Lincoln Electric CompanyJ. M. Gerken, Sr. ConsultantI. D. Harris Edison Welding InstituteL. C. Heckendorn Intech R however, as codes and stan-dards undergo frequent revision, the reader is encouraged to consultthe most recent edit

12、ion.3. American Welding Society (AWS) Committee on Definitions,2001, Standard Welding Terms and Definitions, AWS A3.0:2001,Miami, American Welding Society, p. 67.4. American Welding Society (AWS) Committee on Definitions,2001, Standard Welding Terms and Definitions, AWS A3.0:2001,Miami, American Wel

13、ding Society, p. 51.In automated welding, defined as “welding withequipment that requires only occasional or no obser-vation of the weld, and no manual adjustment of theequipment controls,”5the welders involvement is limitedto activating the machine to initiate the welding cycleand observing the wel

14、d on an intermittent basis, if at all.Robotic welding, defined as “welding that is per-formed and controlled by robotic equipment,”6entailsno involvement on the part of the welding operator inperforming the weld, as the welding operations arecarried out and controlled by welding robots.In both autom

15、ated and robotic welding, however, theoperator plays an active role in quality control throughthe identification of the presence of weld discontinuities.When discontinuities are encountered, appropriate mea-sures must be taken on the part of maintenance or pro-gramming personnel to correct deviation

16、s.Adaptive control welding is defined as “welding witha process control system that automatically determineschanges in welding conditions and directs the equip-ment to take appropriate action.”7This process appli-cation relies on sensors to provide real-time dataregarding abnormalities to the comput

17、er controller. Thecontroller then makes the necessary changes in weldingparameters to produce quality welds. Thus, welding isperformed and controlled without operator interven-tion or supervision.Figure 1 summarizes the capabilities of the differentwelding application methods.5. American Welding Soc

18、iety (AWS) Committee on Definitions,2001, Standard Welding Terms and Definitions, AWS A3.0:2001,Miami, American Welding Society, p. 13.6. American Welding Society (AWS) Committee on Definitions,2001, Standard Welding Terms and Definitions, AWS A3.0:2001,Miami, American Welding Society, p. 64.7. Amer

19、ican Welding Society (AWS) Committee on Definitions,2001, Standard Welding Terms and Definitions, AWS A3.0:2001,Miami, American Welding Society, p. 11.MECHANIZED, AUTOMATED,AND ROBOTIC WELDINGCHAPTER 9MECHANIZED, AUTOMATED, AND ROBOTIC WELDING 3MECHANIZED WELDINGMechanized welding is often selected

20、and implementedto reduce labor costs and improve quality, especiallywhen performing welding and cutting operations involv-ing large components or structures. It can be used toapply most fusion welding and thermal cutting processes.In mechanized welding, the welding operation is per-formed under the

21、observation and control of a weldingoperator. The mechanized welding equipment controlsthe following variables:1. Initiation and control of the welding arc,2. Feeding the welding electrode wire into the arc,and3. Control of movement and travel speed along thejoint.The equipment may or may not perfor

22、m the loadingand unloading of the workpieces.Mechanized welding must allow sufficient time forthe welding operator to monitor and control the guid-ance aspects of the operation as well as the welding pro-cess variables. Weld quality and productivity are oftenenhanced as a result of the proper contro

23、l of processvariables. To perform this task, the operator must bepositioned near the point of welding to observe theoperation closely. He or she interacts continually withthe equipment to ensure the proper placement and qual-ity of the weld metal. Changes to wire feed speed, cur-rent, voltage, torch

24、 position, torch extension, and travelspeed may be required.The travel speed of the carriage is an importantwelding variable, as uniform speed and weld directionduring operation are vital for quality welds. Qualityalso depends on how rigidly the welding carriage is heldto the track because excessive

25、 vibration or dimensionalvariation can adversely affect the wire tip position.Mechanized welding improves the efficiency of theprocess while minimizing operator fatigue, therebyincreasing the consistency and quality of the welds. ThisMethod of Application Manual Semiautomatic Mechanized Automatic Ro

26、botic Adaptive ControlArc WeldingElements/FunctionStarts andmaintainsthe arcPerson Machine Machine MachineMachine(with sensor)Machine(robot)Feeds theelectrodeinto the arcPerson Machine Machine Machine Machine MachineControls theheat for properpenetrationPerson Person Machine MachineMachine(with sens

27、or)Machine(robot) (onlywith sensor)Moves the arcalong the joint (travels)Person Person Machine MachineMachine(with sensor)Machine(robot)Guides thearc alongthe jointPerson Person PersonMachinevia prearrangedpathMachine(with sensor)Machine(robot) (onlywith sensor)Manipulatesthe torch todirect the arcP

28、erson Person Person MachineMachine(with sensor)Machine(robot)Corrects the arcto overcomedeviationsPerson Person PersonDoes not correct; hence, potentialweld imperfectionsMachine(with sensor)Machine(robot) (onlywith sensor)Source: Adapted with permission from Cary, H. B., 1994, Modern Welding Technol

29、ogy, 3rd ed., Englewood Cliffs, New Jersey: Regents/Prentice Hall, Figure 12-1.Figure 1Methods of Applying Welding Processes4 MECHANIZED, AUTOMATED, AND ROBOTIC WELDINGapplication method is capable of yielding uniform,consistent weld profiles when producing long linear orcircumferential welds. When

30、a change in productionrequires a new setup, microprocessors are utilized tochange preset parameters, reducing the likelihood ofhuman setup errors that may cause lower quality weldsand lost production. Mechanized welding requiresfewer starts and stops compared to manual welding,thus reducing the prob

31、ability of various weld discon-tinuities associated with breaking and restarting thewelding arc. A mechanized welding system is shown inFigure 2, which depicts a side-beam carriage perform-ing submerged arc welding on structural columns.SYSTEM COMPONENTSThe system components used in a mechanized wel

32、d-ing installation include a power source, gas supply, wirespool holder, feeding mechanisms, tracking system, andtravel devices.Travel DevicesIn mechanized welding, various travel devices pro-vide a means for moving an automated welding headrelative to the workpiece being welded or vice versa.The wo

33、rkpiece may be stationary while a welding headis moved mechanically along the weld joint, or it maybe moved under a stationary welding head. The traveldevices employed in mechanized welding operations aregenerally grouped into the following four categories:1. Welding carriages,2. Welding head manipu

34、lators,3. Specialized welding machines, and4. Welding positioners.Welding Carriages. Welding carriages provide a rel-atively inexpensive means for arc motion. A typical car-riage rides on a linear or curved track of the samecontour as the joint to be welded, as shown in Figure 3.For welding in the f

35、lat position, some carriages arePhotograph courtesy of The Lincoln Electric CompanyFigure 2Side-Beam Carriage GuidesTwo Submerged Arc Welding Heads for theFabrication of Structural ColumnsMECHANIZED, AUTOMATED, AND ROBOTIC WELDING 5specifically designed to ride on the surface of the mate-rial being

36、welded, whereas others use the actual weldjoint for guidance.Since the welding carriage is designed to permit theoperator to monitor and interact with the system, thecarriage and welding controls are typically placed closeto the operator. In Figure 4, an operator monitors a side-beam carriage with a

37、 twin wire feed system performingsubmerged arc welding on earth-moving equipment.Tractor carriages weld primarily in the flat or hori-zontal position. Other types of welding carriages areemployed for welding in the horizontal, vertical, oroverhead positions. Carriages that are designed to fol-low ir

38、regular joint contours employ a special track orcam upon which the welding carriage is mounted.A self-propelled welding carriage is shown in Figure5. This welding tractor, which travels along the surfaceof the workpiece, employs a tandem submerged arcPhotograph courtesy of The Lincoln Electric Compa

39、nyFigure 3Technician Examines a Side-Beam Carriage with aSubmerged Arc Welding Head Used in a Hardfacing Application6 MECHANIZED, AUTOMATED, AND ROBOTIC WELDINGPhotograph courtesy of The Lincoln Electric CompanyFigure 4Side-Beam Carriage with a Twin-Wire Submerged Arc Welding Systemas Used in an Ear

40、th-Moving Equipment ApplicationMECHANIZED, AUTOMATED, AND ROBOTIC WELDING 7process, often used to perform the large welds requiredin structural, bridge, and ship welding.The side-beam carriage shown in Figure 6 ismounted on a horizontal beam and provides poweredlinear travel for the welding heads. T

41、he powered weld-ing carriage supports the welding head, welding wirefeeder, and usually the operator control panel. Thewelding head is adjustable for vertical height and hori-zontal cross-joint position. The welding operator moni-tors the operation and adjusts the welding position andtravel speed of

42、 the side-beam carriage to accommodatedifferent welding procedures and variations in work-piece fitup.Welding carriages are most productive when used inthe fabrication of long, flat-position groove and filletwelds such as those found in ships and barges as well asin cladding applications for improve

43、d wear or corro-sion resistance. They are also useful in fieldwork, suchas in the erection of bridges and the construction ofstorage tanks.Welding Head Manipulators. Welding manipulatorsare used to position the welding head for longitudinal,transverse, and circular welds. Manipulators typicallyconsi

44、st of a vertical mast and a horizontal boom thatcarries an automated welding head. They usually havepower to move the boom up and down the mast, and inmost units, the mast swivels on the traveling base. Insome manipulators, the welding head moves along theboom; in others, the boom moves horizontally

45、 on themast assembly. Most manipulators have controls thatmove the weld head slowly in the vertical and trans-verse directions. This movement allows the operator toadjust the position of the welding wire to compensatefor variations along the weld joint.A large welding head manipulator carrying a sub

46、-merged arc welding unit is shown in Figure 7. It can beobserved that all welding and manipulating controls areplaced at the operator station.During operation, it is essential that the boom orwelding head move at uniform speeds compatible withthe welding process. The carriage must move uniformlyand

47、at constant speeds if the manipulator is designed tomove along tracks on the shop floor. The manipulatormust be rigid, and deflection must be minimized toreduce the probability of weld wire mislocation.In selecting and specifying a welding manipulator, itis important to determine and compensate for

48、theactual weight to be carried at the end of the boom.Heavy-duty manipulators often support the weight ofthe operator as well as that of the welding equipment.Specialized Mechanized Welding Machines.Specialized mechanized welding machines have customclamping devices, workpiece transfer, load and unl

49、oadsystems, torch travel mechanisms, and other special fea-tures. Welding machines equipped with orbital heads,for example, are used to make circumferential andlongitudinal welds on tanks and cylinders, pipe, andtubing. Other specialized welding machines are used tofabricate flanged beams, weld studs or bosses to plates,and perform special maintenance functions, such asrebuilding track pads for crawler tractors. A specialmechanized welding machine that clamps and weldscovers on axle housings for light trucks is shown inFigure 8.Welding Positioners. A positioner is a mech