Resistance Seam Welding
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Transcript of Resistance Seam Welding
CLASS : EMC7M6
LECTURER : DR ING. YUPITER HARANGAN PRASADA MANURUNG
RESISTANCE SEAM WELDING
• DEFINITION•PROCESS
INTRODUCTION
DEFINITION
Resistance seam welding (RSEW) is a resistance welding process which produces coalescence at the faying surfaces the heat obtained from resistance to electric current through the work parts held together under pressure by electrodes OR A type of continuous weld made between or upon overlapping metal parts.
The resulting weld is a series of overlapping resistance spot welds made progressively along a joint by rotating the electrodes.
Resistance seam welding is another variation on resistance spot welding.
In resistance seam welding, the welding electrodes are motor driven wheels rather than stationary caps. This results in a “rolling” resistance weld or seam weld.
Seam Welding has three parameter : 1. power supplies and control-welding speed, spots per inch,
and timing2. welding wheel configuration- wheels in line(longitudinal) with
the throat of the machine or transverse. 3. sheet configuration.
The welding rollers perform three tasks:1. Weld current transmission2. Welding pressure3. Feed motion transmission
Resistance Seam Welding
Upper Electrode Wheel
Workpiece
Lower Electrode Wheel
Throat
Knurl or FrictionDrive Wheel
Roll Spot Weld
Overlapping SeamWeld
Continuous SeamWeld
[Reference: Welding Handbook, Volume 2, p.553, AWS]
PROCESS
1. The workpiece is passed through the space between the two discs, and under pressure applied by the discs and current flowing through them, a continuous weld is formed.
2. The overlap of the work piece with its comparatively high electrical resistance is intensely heated by the current.
3. With each positive or negative current half-wave the parts are heated to a semi-molten condition, especially at the current peaks.
4. The semi-molten overlap surfaces are pressed together by the welding pressure which causes them to bond together into a uniforming welded structure after cooling.
5. Most seam welded technologies use water cooling through the weld roller assemblies due to the intense heat generated.
•PICTURE•SPECIFICATIONS
SEAM WELDING MACHINE IN THE
WORKSHOP
PICTURES
SPECIFICATIONS
ADVANTAGES
Efficient energy use, with little pollution Fast processing times Easily automated No required filler materials Economical Adaptable to a variety of electrically conductive materials Ability to produce leak-tight welds Can be performed by unskilled operators For certain high strength aluminum alloys, it is practically the
only process applicable Low fumes
DISADVANTAGES
Limited by component shape and wheel access Initial equipment costs Lower tensile and fatigue strengths Thickness of welded sheets is limited - up to 1/4” (6 mm)
•MATERIAL•PROCESS•PRODUCT
APPLICATIONS
MATERIAL
The following metals may be welded :
1. Low carbon steels - the widest application2. Aluminum alloys3. Medium carbon steels, high carbon steels and Alloy steels
(may be welded, but the weld is brittle)
PROCESS
Making flange welds Making watertight joints. Create larger flat-stock parts Join relatively long components Create cylinders, cones, or open-ended boxes
PRODUCT
Containers, radiators and heat exchangers, pressure vessels, tanks, water floats, nuclear components, appliance drums, brewery tanks, motor shells, etc.
•WIDE WHEEL SEAM •NARROW WHEEL SEAM
•CONSUMABLE WIRE SEAM WELDING •MASH SEAM WELDING
•FOIL BUTT SEAM WELDING
TYPES
Wide wheel seam
Wheel contact width normally 5 t mm flat (where t is single sheet thickness in mm).
General purpose welding (domestic radiators up to about 6 m/min).
Narrow wheel seam
Wheel contact shape typically 6mm radius. Knurl drive on wheel edge with contact surface continuously
planished. Controls electrode contamination when welding coated
steels, such as for vehicle fuel tanks.
Consumable wire seam welding
Shaped, consumable copper wire fed between the wheels and sheets to be joined to give consistent clean contact.
Used for welding coated steels such as tin cans and vehicle fuel tanks.
Mash seam welding
Narrow overlap of sheet edges, which are partly crushed together during welding.
High speed welding of tin cans and drums (0.2mm tinplate up to 100m/min).
Wide wheel or consumable wire processes used.
Foil butt seam welding
Foil welded on to each side of the butted edges of the sheets to be joined.
Typically 4mm wide stainless steel foil used to preserve corrosion resistance on coated steel.
Virtually flush finish with no crevice and used to produce wide panels.
•GENERAL•SIZE OF RESISTANCE SEAM WELDS
•LENGTH OF RESISTANCE SEAM WELDS•PITCH OF RESISTANCE SEAM WELDS
WELDING SYMBOL
General
Resistance seam weld symbols have no arrow or other side significance in themselves, although supplementary symbols used in injunction with them may have such significance. Resistance seam weld symbols must be centered on the reference line.
Dimensions of resistance seam welds may be shown on either side of the reference line.
Size of Resistance Seam Welds
The size of resistance seam welds must be designated as the width of the weld expressed in fractions or in decimals in hundredths of an inch and shall be shown, with or without inch marks, to the left of the weld symbol.
The strength of resistance seam welds must be designated as the minimum acceptable shear strength in pounds per linear inch and must be shown to the left of the weld symbol.
Length of Resistance Seam Welds
The length of a resistance seam weld, when indicated on the welding symbol, must be shown to the right of the welding symbol.
When resistance seam welding extends for the full distance between abrupt changes in the direction of the welding, no length dimension need be shown on the welding symbol.
When resistance seam welding extends less than the distance between abrupt changes in the direction of the welding or less than the full length of the joint, the extent must be dimensioned.
Pitch of Resistance Seam Welds
The pitch of intermittent resistance seam welding shall be designated as the distance between centers of the weld increments and must be shown to the right of the length dimension.