servo motors, spot welding, weld qulity, chisel check, weld containment, weld process control, spot welding new AHSS steel

1. TP05PUB99
TECHNICAL PAPER Robust Schedules for Spot
Welding Zinc Coated Advanced
High Strength Automotive Steels
author(s)
G.K.C. TAWADE
S.D. BHOLE
Valiant Machine & Tool
Windsor, Ontario, Canada
A.P. LEE
GARY BOUDREAU
Dofasco Inc.
Hamilton, Ontario, Canada
abstract
Increased use of advanced high-strength steel (AHSS) is necessary for manufacturing
safe, affordable and environmentally responsible vehicles in the future. Spot welding
is still the fastest and most affordable joining process for assembling these steels in
vehicles. More knowledge about spot weldability of these steels is necessary for their
quick implementation. Spot weldability is measured in terms of weld lobes, and wider
(robust) lobes represent better weldability in production environments. The aim of this
work is to develop a robust spot welding process for joining AHSS. Spot welding tests
were conducted on selected material combinations currently used in a production
vehicle. Welding lobes were plotted as per Auto/Steel Partnership (A/SP) standard.
Different types of welding pulses were used to increase the width of the established
weld lobes. Nugget growth study for each type of pulse was conducted to understand
the phenomenon of nugget growth in these steels. A novel welding cycle was designed,
which consisted of two pulses with reduced current intensity on the second pulse. It
was found that the first pulse can effectively remove zinc and the second pulse can
control the nugget growth. Significant increase in the weld lobe was achieved with this
novel welding cycle.
terms
Resistance Spot Welding Multiple Pulsed Welding
Advanced High-Strength Steels Weld Lobe
DP600 Nugget Growth
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