Tweco 100 Weldskill - Manual (Page 32)

weldskill 100 iNVeRTeR
4-10 March 3, 2008
D. Presetting
It is possible in some cases to tell from past experience
or to find by trial and error (or less frequently, to
calculate) how much distortion will take place in a
given welded structure. By correct pre-setting of the
components to be welded, constructional stresses
can be made to pull the parts into correct alignment.
A simple example is shown in Figure 4-22.
E. Preheating
Suitable preheating of parts of the structure other
than the area to be welded can be sometimes used
to reduce distortion. Figure 4-23 shows a simple
application. By removing the heating source from b
and c as soon as welding is completed, the sections
b and c will contract at a similar rate, thus reducing
distortion.
Art # A-07710
Figure 4-25: Welding sequence
Art # A-07711
Figure 4-26: Step back sequence
Art # A-07712
Figure 4-27: Chain intermittent welding
Art # A-07713
Figure 4-28: Staggered intermittent welding
Art # A-07707
Figure 4-22: Principle of presetting
Art # A-07708
Figure 4-23: Reduction of distortion by preheating
Art # A-07709
Figure 4-24: Examples of distortion