View
221
Download
2
Category
Preview:
Citation preview
Veljko SamardzicME-215 Engineering Materials and Processes
Resistance and Solid-State Welding Processes
Chapter 32
Veljko SamardzicME-215 Engineering Materials and Processes
32.1 Introduction
Veljko SamardzicME-215 Engineering Materials and Processes
32.2 Theory of Resistance Welding
Veljko SamardzicME-215 Engineering Materials and Processes
Basic Resistive Welding
FIGURE 32-1 The basic resistance welding circuit.
Veljko SamardzicME-215 Engineering Materials and Processes
Resistive Welding Temperature Distribution
FIGURE 32-2 The desiredtemperature distribution acrossthe electrodes and workpiecesduring resistance welding.
Veljko SamardzicME-215 Engineering Materials and Processes
Current and Pressure for Resistive Welding
FIGURE 32-3 A typical current and pressure cycle for resistance welding. This cycle includes forging and postheating operations.
Veljko SamardzicME-215 Engineering Materials and Processes
Schematic of Resistive Welding
FIGURE 32-4 Thearrangement of the electrodesand workpieces in resistancespot welding.
Veljko SamardzicME-215 Engineering Materials and Processes
32.3 Resistance Welding Processes
Veljko SamardzicME-215 Engineering Materials and Processes
Microstructure of a Resistance Weld
FIGURE 32-5 A spot-weld nugget between two sheets of 1.3-mm (0.05-in.) aluminum alloy. The nugget is not symmetrical because the radius of the upper electrode is greater than that of the lower electrode. (Courtesy Lockheed Martin Corporation, Bethesda, MD.)
Veljko SamardzicME-215 Engineering Materials and Processes
Tear Test
FIGURE 32-6 Tear test of a satisfactory spotweld, showing how failure occurs outside ofthe weld.
Veljko SamardzicME-215 Engineering Materials and Processes
Resistive Welder
FIGURE 32-7 Single-phase,air-operated, press-typeresistance welder withmicroprocessor control.(Courtesy Sciaky Inc., Chicago, IL.)
Veljko SamardzicME-215 Engineering Materials and Processes
Spot Welding Application
Veljko SamardzicME-215 Engineering Materials and Processes
Spot Welding Seams
FIGURE 32-8 Seam weldsmade with overlapping spotsof varied spacing. (CourtesyTaylor-Winfield Corporation,Brookfield, OH.)
Veljko SamardzicME-215 Engineering Materials and Processes
Schematic of Seam Welding
FIGURE 32-9 Schematicrepresentation of theseam-welding process.those
Veljko SamardzicME-215 Engineering Materials and Processes
Tube WeldingFIGURE 32-10 Using high- Squeeze rollfrequency AC current to producea resistance seam weld in buttweldedtubing. Arrows from thecontacts indicate the path of thehigh-frequency current
Veljko SamardzicME-215 Engineering Materials and Processes
Projection Welding
FIGURE 32-11 Principle ofprojection welding (a) prior toapplication of current andpressure and (b) after formationof the welds.
Veljko SamardzicME-215 Engineering Materials and Processes
32.4 Advantages and Limitations of Resistance Welding
Veljko SamardzicME-215 Engineering Materials and Processes
32.5 Solid-State Welding Processes
Veljko SamardzicME-215 Engineering Materials and Processes
Process Summary for RW
Veljko SamardzicME-215 Engineering Materials and Processes
Cold Welding
FIGURE 32-12 Small parts joined by cold welding. (Courtesy of Koldweld Corporation, Willoughby, OH.)
Veljko SamardzicME-215 Engineering Materials and Processes
Roll Welding
FIGURE 32-13 Examples ofroll-bonded refrigerator freezerevaporators. Note the raisedchannels that have beenformed between the roll-bondedsheets. (Courtesy Olin Brass,East Alton, IL.)
Veljko SamardzicME-215 Engineering Materials and Processes
Friction Welding
FIGURE 32-14 Sequence for making a friction weld. (a) Components with square surfaces are inserted into a machine where one part is rotated and the other is held stationary. (b) The components are pushed together with a low axial pressure to clean and prepare the surfaces. (c) The pressure is increased, causing an increase in temperature, softening, and possibly some melting. (d) Rotation is stopped and the pressure is increased rapidly, creating a forged joint with external flash.
Veljko SamardzicME-215 Engineering Materials and Processes
Schematic for Friction Welding
FIGURE 32-15 Schematic diagram of the equipment used for friction welding. (Courtesy of Materials Engineering.)
Veljko SamardzicME-215 Engineering Materials and Processes
Inertia Welding
FIGURE 32-16 Schematicrepresentation of the varioussteps in inertia welding. Therotating part is now attachedto a large flywheel.
Veljko SamardzicME-215 Engineering Materials and Processes
Examples of Friction Welding
FIGURE 32-17 Some typicalfriction-welded parts. (Top)Impeller made by joining achrome–moly steel shaft to anickel–steel casting. (Center)Stud plate with two mild steelstuds joined to a square plate.(Bottom) Tube componentwhere a turned segment isjoined to medium-carbon steeltubing. (Courtesy of Newcor BayCity, Division of Newcor, Inc.,Royal Oak, MI.)
Veljko SamardzicME-215 Engineering Materials and Processes
Stir Welding
FIGURE 32-18 Schematic of the friction-stir welding process. The rotating probe generates frictional heat,while the shoulder provides additional friction heating and prevents expulsionof the softened material from the joint. (Note: To provide additional forgingaction and confine the softened material, the tool may be tilted so thetrailing edge is lower than the leading segment.)
Veljko SamardzicME-215 Engineering Materials and Processes
Example of Stir Welding
FIGURE 32-19 (a) Top surfaceof a friction-stir weld joining 1.5-mm- and 1.65-mm-thickaluminum sheets with 1500-rpmpin rotation. The welding toolhas traversed left-to-right andhas retracted at the right of thephoto. (b) Metallurgical crosssection through an alloy 356aluminum casting that has beenmodified by friction-stirprocessing.
Veljko SamardzicME-215 Engineering Materials and Processes
Features of Stir Welding
Veljko SamardzicME-215 Engineering Materials and Processes
Schematic of Ultrasonic Welding
FIGURE 32-20 Diagram of theequipment used in ultrasonicwelding
Veljko SamardzicME-215 Engineering Materials and Processes
Application of Ultrasonic Welding
Veljko SamardzicME-215 Engineering Materials and Processes
Explosive Welding
FIGURE 32-21 (Left) Schematic of the explosive welding process. (Right) Explosive weld between mild steel and stainless steel, showing the characteristic wavy interface.
Recommended