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Iron
Foundry
In 1973,
a British engineering firm designed and installed a large
continuous iron foundry in an African workshop. The firm closed
operations 20 years later leaving the workshop with no engineering
support. Later, the sand cooling system completely failed,
interrupting the re-processing of the foundry sand and necessitating
manual work. The workshop invited DIAK to solve the problem.
It was clear that there was no point in recreating the same
system since the technical process was inaccurate and relied
on obsolete components. Instead DIAK designed and assembled
a complete replacement system built onto framework sections
exactly to match the mounting of the original. This would
permit the old system to be hoisted out from above the sand
conveyor on the overhead gantry, and the new system to be
dropped in with no further work for the user apart from wiring
the main power connection.
The new
systems used Siemens EPROM logic chips which were programmed
with the entire system operation. The volume of sand passing
by on the conveyor was measured by fibre-optic sensors, and
the temperature and moisture content by a dielectric capacitance
"surface-ski" float. The EPROM calculated the sand
condition and instantaneously controlled pressurised water
jets in the next zone into which the sand conveyor passed.
The sand then dropped into a rotating mixer and back to the
foundry shop floor ready for use. Each part of the system
was protected against the hostile environment- the fibre-optic
units were continuously cleaned by air jets, the EPROM sealed
in a IP65 cabinet, and the condition of the float continuously
monitored. The EPROM controlled alarms to alert operators
on the ground of such faults as failure of the sand supply
to arrive, and it also performed controlled shut-down procedures.
The system worked first time and needed no user intervention
thereafter.
One year
later, DIAK performed a 2nd major project in the foundry when
a new 2 ton shake-out machine was installed together with
the sand transport- a screw augur conveyor, vibratory feeder,
moving belt and rotating feed hopper. All other conveyor belts
were also replaced.
The 3rd
phase and the end of the basic overhaul was completed one
year later in cooperation with David Brown Engineering when
all of the gearboxes and drives were rebuilt for each stage
of the foundry, followed by a full overhaul of the jolt squeeze
machines.
Engineering
Workshop
In 1970,
a major engineering workshop in Africa acquired a centre lathe,
a large 18 inch capacity machine, which has since seen good
service for many years. The UK manufacturer closed a few years
after the delivery, but solid engineering design kept the
machine running for many years. However a sudden fracture
in the drive gearbox wrecked several gears and the clutch,
leaving the user with no apparent alternative but to seek
a new machine.
An on-site
inspection by DIAK resulted in a proposal to collect the broken
parts and airfreight them to the DIAK U.K. works. There the
parts were examined and tacked back together for CNC dimensions
to be taken and gear formations to be mapped. DIAK then machined
complete new replacement parts to match the broken items.
A current production clutch was adapted and shipped with the
new parts. The lathe returned to full service at a repair
cost less than 10% of the replacement price of a new machine.
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