The manufacture of BigHead
fasteners depends on one core requirement
- the ability to weld a thin, large-diameter
metal head to a stud or collar, at a strength
equal to that of the metal of which it's
made. This central skill is at the heart
of the BigHead product range, and with the
company's latest automatic welding machine
now in full production, a major increase
in production capacity is on-line, helping
to produce the company's range of over 1,200
variants.
Designed and built by BigHead's technical
staff with the help of BWP Technical Services
Ltd., the Twinhead is capable of producing
two sizes of BigHead simultaneously at a
production rate of some 3,000 per hour,
at zero defect levels. The machine requires
no labour, and is believed to be "unique"
in the world. "We invented the BigHead 40
years ago," says BigHead's MD Brian Giddings,
"and we are unaware of anyone, anywhere,
even capable of knowing how to start the
design." The machine consists of two auto-welders
built on a single chassis; each is fed by
two bowlfeeds, with feeder tracks leading
directly to the eight weldheads on each
"side". Each weld, incorporating up to six
weld cycles at varying current and hydraulic
pressure, takes less than half a second.
Three separate sensor systems check up to
six parameters, to give the weld a tailored
melt and optimum grain structure. This allows
for studs from M4 to M8 thread to be welded
to heads from 15mm to 38mm in diameter,
either in mild or 316 stainless steel.
Malcolm Hall, Hall-Fast’s Managing Director commented:
"it
is very important that any products supplied
by ourselves are manufactured to very high
quality standards, it is also essential
that our suppliers are forward thinking
and are able to offer us the technical support
and service levels that our customers and
ourselves require, BigHead's huge investment
in the Twinhead will be of great benefit!" |
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The Twinhead is fully software-controlled; this picture shows the touchscreen control panel and RH multi-head welding area |
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| The eight weld heads on each side are fitted with individual head and stud guides relevant to specific head/stud diameters. |
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| The stud bowl feed for the RH side of the Twinhead, feeds an M6x12 stud to be welded to the B15 head - used in the Bentley Continental |
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