Product category:
Metals processing plant and equipment
News Release from: Metalock Engineering | Subject: Machine and furnace repairs
Edited by the Manufacturingtalk Editorial
Team on 16 December 2004
Hearth shell bores machined in-situ
As part of a complete blast furnace rebuild programme Metalock machined fifteen hearth shell bores on site at the furnace to accommodate tapered tuyere cooler holders.
Metalock Engineering UK, based in Coventry, is an established global mechanical equipment repair company Since the company was established in 1947 it has built up an outstanding reputation in the steel industry for quality work delivered on time and within budget
This article was originally published on Manufacturingtalk on 2 Dec 2004 at 8.00am (UK)
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Recently, as part of a complete blast furnace rebuild programme for Dofasco, a fully integrated steel producer from raw materials through to coated steel sheet, in Canada, Metalock machined fifteen hearth shell bores to accommodate tapered tuyere cooler holders.
Metalock Engineering UK secured the contract on a competitive basis.
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Metalock Engineering UK's task was to bore out the shell bosses to accept the tapered tuyere cooler holders which house the coolers themselves and the copper tuyeres used to inject hot blast air at over 2000 deg C into the furnace just above the hearth area.
The first operation for the Metalock team was to assemble a drill jig on the inside and outside faces of No 1 tuyere holder to drill and tap four equi-spaced holes 0.625in diameter x 1in deep on a 38.5in PCD (16mm by 25mm deep on a 978mm PCD - pitch circle diameter).
These holes were used to mount a boring bar assembly, with inner and outer bearing supports, to machine the tapered cooler holder bores.
To position the boring bar assembly accurately, a telescope was fitted to the outer end and the bar aligned visually with the furnace central datum and a datum point on the opposite inner shell through a central hole in the bar.
Being equi-spaced around the shell circumference at 24 degree intervals, the tuyeres were not diametrically opposite each other.
Two purpose-designed boring machines, built by Metalock, incorporated hydraulic drive gearboxes and a toolpost assembly that traversed along linear rails set at an angle of 7 degrees to produce the taper required through each of the fifteen 5.187in (132mm) thick tuyere bosses.
Then the faces and the inner diameter of the bore was machined to 31.921in (811mm).
The outer bore was stepped by a further 0.125in (3mm) to provide relief for the cooler holder and give a diameter of 33.980in (863mm).
Using two identical machines each working on adjacent cooler holders simultaneously, Metalock was able to substantially speed up the machining process.
Work continued round the clock using three men per shift to complete the schedule on time.
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