V-21A 5
INTRODUCTION
INTRODUCTION
The complete range of Taylor Studwelding Systems Capacitor Discharge units
are compact, portable Stud Welding equipment. The units are specically designed
to enable a small diameter range of ferrous and non-ferrous weld studs to be
welded to light gauge, self-nish or pre-coated materials, in most cases with lile or
no reverse marking.
The equipment consists of a control unit, a welding pistol and the necessary
interconnecng cables and accessories (see page 6 for the equipment schedule).
THE PROCESS
Capacitor Discharge stud welding is a form of welding in which the energy
required for the welding process is derived from a bank of charged capacitors. This
stored energy is discharged across the gap between the two surfaces to be welded
as they are propelled towards each other. The arc produced heats the two surfaces,
melng a thin lm of metal on each surface and the propelling force closes the gap
between the two faces, thus forming a weld.
In contact welding the stud to be welded is forced by spring pressure against
the work piece. At this point the arc gap between the two components is
maintained by a small pip on the welding face of the stud. On iniaon of the high
current pulse from the capacitors, this pip vaporises and an arc is drawn between
the work piece and the stud. The heat from this arc melts the base of the stud and
the area of the work piece directly beneath the stud, whilst the spring pressure
from the pistol accelerates the stud towards the work piece. Within 3-4
milliseconds the stud hits the work piece and the arc is exnguished. The kinec
energy contained in the moving stud and the remaining spring pressure, forge the
molten parts together to form a weld.
Li Gap welding uses a soer spring than contact. This is especially helpful
when welding soer materials e.g. Aluminium as the strong spring in a contact
pistol can damage the pip on the stud aer more than relavely brief contact. Li
Gap also uses a solenoid coil in the pistol. When the trigger is pressed the coil is
energised momentarily, liing the stud away from the work piece to a pre-
determined height and releasing, allowing the stud to accelerate back towards the
work piece. The high current pulse iniates on contact and the weld takes as in
contact welding but at a much faster rate (1-2 milliseconds) because of the
acceleraon from the li.
