Posted on 19 Feb 2016
In late December 2015, a stainless
steel continuous tandem cold mill (TCM) supplied by Primetals
Technologies to Beihai Chengde Stainless Steel Co. (Beihai Chengde)
produced the first coil at the Beihai plant in the Chinese Guangxi
Province. The mill consists of a Power X-HI type, five-stand, continuous
tandem cold rolling mill and a heavy laser welder. The rolling mill has
a rated capacity of 600,000 tons of cold strip per year, and is
designed to produce AISI grades series 200 and 300. The cold test was
performed within 17 days and the first coil produced within only three
months. The order was placed in the mid-2013. It was the second order
for an X-HI and the third order for a continuous TCM for stainless steel
that Primetals Technologies had received from China.
Beihai
Chengde is active in nickel mining and the production of narrow
stainless steel strip. The company intends to use the new cold rolling
mill to start producing wide strip. The continuous rolling mill handles
hot-rolled, annealed and pickled stainless steel. It is able to achieve
exit thicknesses from 0.3 to 3.0 millimeters from entry thicknesses of
between 1.0 and 5.0 millimeters. The width of the strip varies between
800 and 1,300 millimeters.
The continuous rolling mill
line comprises three main sections, each separated by strip
accumulators. The entry section includes a double uncoiler station, each
equipped with coil storage facilities, coil loading car and overhung
mandrel uncoiler together with coil opening, flattening and shearing
equipment. The Primetals Technologies welding machine is of heavy laser
type (LW21H) and includes strip centering and strip cutting facilities
as well as diagnostic systems.
The mill section includes
five stands of Power X-HI type with associated high tension bridles and
rinsing section to remove emulsion from the strip surface. The rolling
speed is 400 meters per minute. The rolling stands are designed for a
flying roll change, so production will not have to be interrupted to
change the work rolls. This increases productivity and reduces output
losses.
The exit section comprises exit bridle,
inspection station, rotary shear, scrap and sample cutting, two
recoilers, belt wrapper, paper interleaving feeding equipment, spool
loading and coil unloading car with associated coil banding and storage.
The strip looper between the rolling line and the exit section
decouples the rolling process from the downstream activities, such as
strip inspection and coil shearing. This means that these are no longer
limiting factors on the mill throughput.
The scope of delivery also included variable-speed Sinamics drives with a total power of 22,000 kilowatts, and the basic (level 1) and process (level 2) automation. A Simatic WinCC-based solution handles operator control and monitoring tasks. It also enables distributed supervision, and features easy-to-use diagnostic and alarm functions.
