|
Dofasco
Dofasco successfully entered the tubular business in 1997 with the construction of its No. 1 Tube Mill. With
the success of this first mill, a second was soon required.
JNE Consulting headed up the design engineering for the No. 2 Tube Mill, including all civil, mechanical and
electrical engineering, as well as coordination between equipment suppliers.
The No. 2 Tube Mill, like its predecessor, produces tube by forming hot rolled plate steel into a continuous
tubular section which is welded at the seam, then cut into various mill lengths.
The mill lengths are then processed through a finishing floor, or re-cutting operation, where the mill lengths
are re-cut into specified lengths, de-burred (removing jagged edges left by the cutting process), cleaned and
packaged into bins for shipment. This complete process is fully automated with minimal manual intervention.
The tubes are then further processed by other companies using tubular hydroforming, which consists of
forming and shaping the tube in a mold using immense water pressure. Compared to results of conventional
methods of overlapping and welding, the resulting hydroformed parts are lighter, of better quality and have
lower production costs. These parts are used in various frame components of popular vehicles such as
General Motor’s Jimmy and Blazer.
The requirements of the automotive industry for larger tubes, increased diameter-to-thickness ratio, different
shapes (rectangle, ellipse and other), and various lengths have
mill equipment vendors sharpening their pencils and envisioning
new designs to meet the current production demand.
The challenge for the No. 2 Tube Mill is the demand for
re-cutting large diameter tubes rapidly while keeping the cut
quality within stringent tolerances.
The project team examined three distinct cutting methods —
shearing, band-sawing, and cold sawing (circular saws).
Shearing was fast and band sawing was cost effective, but
cold saws delivered the best combined speed and cut quality.
A prototype saw, developed for Dofasco by NAC (a division of New Automation Corporation), operates on the
principle of varying the feed rate of the blade through the tube. The results are a very rapid and clean cut.
JNE also provided engineering for a 125,000-square-foot warehouse, erected in a disused coil yard, to store
tubes from the No. 1 and No. 2 Tube Mills. The warehouse is heated by three 2,500 MBH vertical heaters in
the winter, and dehumidified by two 160-ton mechanical refrigeration units in the summer to maximize the
storage life of the tube product.
|
