AWS RWPH-2011 Resistance Welding Pocket Handbook (1st Edition).pdf

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1、AWS RWPH:2011Resistance WeldingPocket HandbookAWS RWPH:2011Resistance Welding Pocket Handbook1st EditionPrepared by theAmerican Welding Society (AWS) J1 Committee on Resistance Welding EquipmentWith guidance from theAWS RWMA CommitteeUnder the Direction of theAWS Technical Activities CommitteeAbstra

2、ctGeneral information relating to the operation of common resistance welding equipment.AWS RWPH:2011 2International Standard Book Number: 978-0-87171-785-6American Welding Society550 N.W. LeJeune Road, Miami, FL 331262011 by American Welding SocietyAll rights reservedPrinted in the United States of

3、AmericaPhotocopy Rights. No portion of this standard may be reproduced, stored in a retrieval system, or transmittedin any form, including mechanical, photocopying, recording, or otherwise, without the prior written permissionof the copyright owner.Statement of Use. Although care was taken in choosi

4、ng and presenting the data in this pocket handbook, AWS cannot guarantee that it is error free. Further, this Pocket Handbook is not intended to be an exhaustivetreatment of the topic and therefore may not include all available information, including with respect to safetyand health issues. By publi

5、shing this Pocket Handbook, AWS does not insure anyone using the information it contains, against any liability or injury to property or persons arising from that use.This booklet contains:a71basic information on resistance weldinga71important “dos” and “donts”a71common weld defects and their probab

6、le causesa71various charts including sample weld schedulesWhile this pocket handbook contains important safety tips, it is NOT a safety manual. Nor is it an operatorsmanual or a maintenance manual. It cannot take the place of any of these. Similarly, it is not an industry standard and does not repla

7、ce any existing industry standards. Its sole purpose is to help you make better andmore consistent welds.For additional information please consult other AWS technical documents relating to resistance welding.Assistance can also be obtained from the members of the RWMA Committee of the American Weldi

8、ng Society.AWS RWPH:2011 3Table of ContentsAWS RWPH:2011 4Spot Welding Electrode Shapes.20Electrode Dos21Electrode Donts 22Effect of Electrode Wear on Welding24Electrode Face to Body Diameter Guidelines 25Importance of Water Tubes26Important Welding Hints .27Weld Defects and Causes29Recommended Prac

9、tices.31Spot Welding Low Carbon Steel .32Spot Welding Galvanized Low Carbon Steel.33Spot Welding HSLA Steel .34Spot Welding Aluminum .35Projection Welding Low Carbon Steel 37Seam Welding Low Carbon Steel39Flash Welding 40Common Conversions.42Other Documents on Resistance Welding.43What is a Resistan

10、ce Weld? .5Why Resistance Weld?6The Resistance Welding Processes.7Spot Welding7Projection Welding.8Seam Welding 9Upset Welding (Butt Welding).10Flash Welding 10Hot Upsetting.11Resistance Brazing/Resistance Soldering11Resistance Parting11Resistance Heating.11Machine Nomenclature.12Rocker Welder .12Pr

11、ess-Type Welder .13Seam Welder 14Upset or Flash Welder .15Resistance Welding Guns 16Resistance Welding Electrodes.18Electrode Material Types .18AWS RWPH:2011 5What is a Resistance Weld?Upper ElectrodeFaying Surface ofMaterial to beWeldedLower ElectrodeElectrodeForceElectrodeForceResistance to flow o

12、felectrical current generatesheat quickly causing a weldFigure 1Basic Resistance Weld ConfigurationIt is the localized fusion of metal where the heatrequired for coalescence is caused by the flowof electric current through the workpieces andpressure is applied by the electrodes to forge theparts tog

13、ether. An example resistance weldingconfiguration is shown in Figure 1.Why Resistance Weld?The advantages of resistance welding are many and include the fact that it is:a71An economical processa71Adaptable to a wide variety of materials including low carbon steel, coated steels, stainless steel,alum

14、inum, nickel, titanium, and copper alloysa71Applicable to a variety of metal thicknessesa71A process with short cycle timesa71A robust processa71Tolerant to fit-up variationsFor additional information on the process or equipment, consult relevant literature from the list onpages 43 to 45, and/or con

15、tact any of the member companies of the AWS RWMA (ResistanceWelding Manufacturing Alliance) Committee, or the resistance welding equipment members of theAWS WEMCO (Welding Equipment Manufacturers Committee).AWS RWPH:2011 6The Resistance Welding ProcessesAWS RWPH:2011 7Spot WeldingIn this most widely

16、 used resistance weldingprocess, two opposing electrodes apply forceand current to metals that overlap (lap joint).Figure 2 shows examples of the various types ofspot welds. Additional information may befound in Chapter 1 of the AWS WeldingHandbook, 9th Edition, Vol. 3, or Chapter 2 ofthe RWMA Resis

17、tance Welding Manual.SeriesDirect IndirectPush-PullFigure 2Types of Spot WeldsProjection WeldingIn this variation of the resistance weldingprocess, the metals to be welded meet at a local-ized point, which exists to concentrate the forceand current. In some parts, such as cross-wirewelding, the loca

18、lized point of contact resultsfrom the natural part geometry. Most of thetime, the projection must be formed ormachined in one of the parts. Figure 3 showssome examples of projections before welding.Additional information may be found inChapter 2 of the AWS Welding Handbook, 9thEdition, Vol. 3, or C

19、hapter 3 of the RWMAResistance Welding Manual.AWS RWPH:2011 8SPHERICAL TYPE ELONGATED TYPERING-FILLET TYPE RING TYPECROSS-WIRE TYPE EDGE TYPEFigure 3Types of Projection WeldsSeam WeldingSimilar to spot welding, except the circular elec-trodes (seam welding wheels) are rotating whenthe weld is being

20、made. If the time between thewelds is increased such that the welds do notoverlap to form a continuous seam weld, theresult is known as a roll spot weld. Additionalinformation may be found in Chapter 1 of theAWS Welding Handbook, 9th Edition, Vol. 3, orChapter 4 of the RWMA Resistance WeldingManual.

21、AWS RWPH:2011 9CONTINUOUS SEAM WELDEDELECTRODE WHEELWORKELECTRODE WHEELWORK INTERMITTENT(ROLL SPOT) WELDEDWIDE LAP1/2 MASH OR NARROW LABSEAM WELDEDELECTRODE WHEELWORKFigure 4Seam WeldingUpset Welding (Butt Welding)The ends of the two parts are forced togetherwhile welding current and force are appli

22、ed.Flash WeldingDuring the initial sequence, the parts are heldlightly together while current is applied. Then asmaterial is flashed away and the proper temper-ature is reached the parts are forced together tocomplete the weld.Additional information on these processes maybe found in Chapter 3 of the

23、 AWS WeldingHandbook, 9th Edition, Vol. 3, or Chapter 5 ofthe RWMA Resistance Welding Manual.AWS RWPH:2011 10FIXEDPLATENMOVEABLEPLATENTRANSFORMERCLAMPSa. AXIALLY ALIGNED WELDCROSS-SECTION AFTERWELDING-UNTRIMMEDFIXEDPLATENMOVEABLEPLATENCRO SS-SECTION AFTERWELDING-UNTRIMMEDb. MITER WELDCROSS-SECTION A

24、FTERWELDING-UNTRI MMEDc. RING WELDTRANSFORMERFIXEDPLATENMOVEABLEPLATENTRANSFORMERFigure 5Common Upset and Flash WeldingConfigurationsHot UpsettingIn this process, heat is created by electrical current and then the workpiece is upset by the electrodeforce. Hot upsetting is commonly applied to rivets

25、and pins to lower the force required to create ahead and/or bulge.Resistance Brazing/Resistance SolderingThese are processes where the heat created by the resistance to current flow through two parts is usedto melt a low-temperature filler metal.Resistance PartingAs the metal is heated by the electr

26、ic current in this process, force is applied to separate the work-piece midway between the electrodes.Resistance HeatingHeat is created in the workpieces for hot forming and heat-treating applications.Additional information on these processes may be found in Chapter 6 of the RWMA ResistanceWelding M

27、anual.AWS RWPH:2011 11Machine NomenclatureAWS RWPH:2011 12TRANSFORMERSHUNTCOVERHORNAIR VALVEBASECOLUMNHORNTRANSFORMER SWITCHAIRCYLINDERFILTER,REGULATOR,LUBRICATOR(FRL)ELECTRODE HOLDERLOWER HORN HOLDERUPPER HORNHOLDERROCKERARMFOOT SWITCHWATERCOOLINGWATERCOOLINGRocker WelderPress-Type WelderAWS RWPH:2

28、011 13TRANSFORMERCOLUMNBASELOWER HORNAIRCYLINDERUPPERHORNUPPER HORNHOLDERELECTRODEHOLDERFOOTSWITCHTRANSFORMERSWITCHFILTER,REGULATOR,LUBRICATOR(FRL)AIR CYLINDERREGULATORAIRVALVERAMLOW FRICTIONHEADLOWERHORNHOLDERWATERCOOLINGWATER COOLINGSeam Welder(Circumferential Type Illustrated)AWS RWPH:2011 14RESI

29、STANCEWELDINGTRANSFORMER AIR CYLINDER BASE UPPER CIRCULARELECTRODE LOWER CIRCULARELECTRODE KNEE BUSS BAR RAM KNEE JACK LOWERBEARING BOX UPPERBEARINGBOX DRIVE GEAR BOX Upset or Flash WelderAWS RWPH:2011 15RESISTANCEWELDINGTRANSFORMER BASE STATIONARYPLATTEN LOWER STATIONARYELECTRODE OPERATORSTATION UP

30、SETCYLINDER POSITIONSENSOR CLAMP CYLINDERS UPPER STATIONARYELECTRODE UPPER CLAMP ARM MOVABLEPLATTEN ELECTRICALJUNCTION BOX GREASEFITTINGMANIFOLDResistance Welding GunsAWS RWPH:2011 16P (PINCH) -TYPES (SCISSOR) -TYPE LINK ASSEMBLY GUN CRADLE WELDING STATIONARY GUN BODY PNEUMATIC ACTUATOR BENT ELECTRO

31、DE ADAPTER ELECTRODE CAP TIP POSITIONING CYLINDER FULCRUM PIN BARREL LOCK CLEVIS MOVEABLE GUN BODY RESISTANCE TRANSFORMER LAMINATED SHUNT FULCRUM PIN LINK ASSEMBLY STATIONARY GUN BODY SPRING EQUALIZER BENT ADAPTER ELECTRODE CAP BARREL LOCK CLEVIS Resistance Welding GunsAWS RWPH:2011 17EQUALIZING C-T

32、YPEX-TYPE RESISTANCE WELDING TRANSFORMER GUN CRADLE LAMINATED SHUNT STATIONARY GUN BODY EQUALIZING SLIDE ASSEMBLY BENT ELECTRODE ADAPTER STRAIGHT ELECTRODE ADAPTER ELECTRODE CAP HEX ADAPTER BARREL ADAPTER WELD GUN MOUNTING BRACKET PNEUMATIC ACTUATOR BARREL LOCK SHUNT ADAPTER PNEUMATIC ACTUATOR ADJUS

33、TABLE STOP CABLE LUG ELECTRODE CAP BENT ADAPTER BARREL LOCK STATIONARY GUN BODY MOVEABLE GUN BODY FULCRUM PIN WATER FITTING Resistance Welding ElectrodesAWS RWPH:2011 18The welding electrodes serve three functions:a71They hold the workpieces together under pressure.a71They provide a path for the wel

34、ding current into and out of the workpieces.a71They cool the outer surface of the workpieces. This permits the inner (faying) surfaces to get hotenough to fuse without welding the workpieces to the electrodes.Electrode Material TypesThe RWMA has defined classes (groups) of materials with similar pro

35、perties to make it easier toselect the proper electrode material. The important properties to consider for successful resistancewelding are the hardness and conductivity of the electrodes. Some of the more common materials arelisted in Table 1 (Page 19).Table 1RWMA Material ClassificationsClass Hard

36、nessaConductivitybCommon General PurposeMaterials1 65 80 CuZr Spot and seam welding of aluminum/magnesium (C15000) alloys, coated materials, brass, and bronzes.2 75 75 CuCrZr Spot and seam welding of cold- and hot-rolled (C18150) steel, stainless steel and low-conductivity brass CuCr and bronze. The

37、y are also used for welding (C18200) galvanized steel and other coated materials3 90 45 CuCoBe (C17500) High hardness makes them ideal for spot and CuNiBe seam welding of high resistance materials such (C17510) as stainless steels, Nichrome, Inconel and Monel CuNiSiCr metal. Also used for current-ca

38、rrying structural (C18000) parts.11 94 40 CuW Projection welding electrodes; flash and butt (C74400) welding electrodes.20 45 75 CuAl2O3Welding of metallic coated metal such as (C15760) galvanized steel terne plate, etc.aThe hardness values correspond to the Rockwell B scale.bConductivity is indicat

39、ed by making a comparison to the conductivity of pure copper. The scale is called IACS (InternationalAnnealed Copper Standard) where pure copper has a conductivity value of 100% IACS.AWS RWPH:2011 19Table 2Spot Welding Electrode ShapesElectrode Nose TypeNose Geometry A B C D E FRWMAaISO StandardbaRe

40、f. AWS D8.6.bRef. ISO 5184.AWS RWPH:2011 20Electrode DosSelectiona71Use the proper electrode material for the job you are doing.a71Use standard electrodes wherever possible.a71Use the most suitable electrode diameter for the thickness of stock being welded.a71Use ejector type holders for easy remova

41、l of electrodes and to avoid damage to tapers.Water Coolinga71Be sure the internal water-cooling tube of the holder projects into the electrode water hole to thebottom of the electrode (Figure 7, Page 26).a71Be sure the exposed end of water-cooling tube is cut at an angle so the water flow will not

42、bestopped if it butts tightly against the inside of the electrode.a71Connect the water supply hose to the proper holder inlet so that the water flows through the water-cooling tube first.a71Internally cool the spot welding electrodes with cold water flowing at a rate of at least 3/4 gal 3 L per minu

43、te.a71Use visual flow indicators or sensors to verify water flow to the electrodes.AWS RWPH:2011 21Maintenancea71Use approved LOCK OUT/TAG OUT procedures while performing maintenance.a71Keep the electrode taper and holder taper clean, smooth and free of foreign deposits.a71Use a rawhide, rubber, pla

44、stic, or brass mallet for striking holder or electrodes in aligning opera-tions.a71Dress spot-welding electrodes frequently enough to maintain the quality of the welds.a71Machine dress electrodes to their original contour whenever possible.a71Use properly designed knurling wheels to maintain proper

45、seam welding wheel shape.Electrode DontsSelectiona71Do not use unidentified electrodes or electrode materials.a71Avoid special offset or irregular electrodes when the job can be done with standard straight elec-trodes.a71Do not use small electrodes on heavy gauge welding, or large electrodes on smal

46、l work.a71Avoid the use of seam welder wheels too thin to stand the heat or pressure of your job.AWS RWPH:2011 22Water Coolinga71Do not forget to turn on the cooling water before starting to weld.a71Never use water hoses that will not fit the holder water connection fittings snugly.a71Do not allow w

47、ater connections to become leaky, clogged, or broken.a71Avoid using holders with leaking or deformed tapers.a71Avoid electrode holders that do not have an adjustable internal water-cooling tube.a71Do not permit the water system to be restricted by accumulation of deposits.Maintenancea71Never put han

48、ds inside working area without turning off all power and using approved LOCKOUT/TAG OUT procedures.a71Avoid the use of pipe wrenches or similar tools in removing electrodes.a71Avoid using any materials to seal a leaking taper.a71Never permit a spot welding electrode to mushroom enough to make dressi

49、ng difficult.a71Avoid dressing electrodes with a file.a71Do not strike the holder or electrode with a steel hammer in aligning the welder arms.AWS RWPH:2011 23AWS RWPH:2011 24Effect of Electrode Wear on WeldingTable 3 below illustrates the effect of changes in the weld face diameter. This table was developed witha 1/4 in 6 mm diameter weld face using 600 lbs 2,670 N weld force and 10,000 A of welding current.Table 3Effect of Tip Area on Welding ParametersWeld Face 1/8 in 1/4 in 5/16 in 3/8 in 1/2 in 5/8 in 3/4 in Diameter 3 mm 6 mm 8 mm 10 mm 13 mm 16 mm 19 mmW