ROLLING MILLS
www.machyintl.com
20 Commerce Drive North Branford, CT 06471 USA Tel: +1 203-484-0400 Fax: +1 203-484-4499 sales@machyintl.com
ROLLING MILLS By John Conroy
Most machinery dealers sell equipment designed to shape, fabricate, or cut metal of thin gauge in either sheets or coils. But how do you get from ingots cast as thick as 18” into coil form at very specific thin gauges? The answer is the rolling mill. Rolling mills have one purpose in life - to reduce the thickness of metal by crushing it between power-driven rolls. Rolling mills come in many configurations. They can be hot mills or cold mills. Hot mills are used for the initial breakdown of thick ingots that are preheated bright red to allow for greater reduction per pass. Hot mills can be reversing or consist of a series of multiple rolling mills in tandem. Cold mills, the more common type, take less reduction per pass but can produce metal in the very thin gauges required for finished product in coil form. Rolling mills are designated by their roll size. For example an 8” x 10” 2-hi mill means that the roll diameter is 8” and the roll face width is 10”. A 4-hi mill uses two smaller diameter work rolls supported by two larger diameter backup rolls immediately above and below the work rolls. A 2” x 8” x 10” 4-hi mill means the work roll diameter is 2”, the backup roll diameter is 8”, and the roll face width is 10”. Cluster mills, which utilize even smaller diameter work rolls that are supported in multiple layers of backup rolls, generally produce the thinnest gauges with the greatest tolerance, although advances in roll material and roll bearings today allow for high precision 4-hi mills that can do much the same work as 20-hi Sendzimir cluster mills. The general rule is that the larger the diameter of the work roll the more reduction you can take on the metal. So breakdown mills and hot mills are typically 2-hi mills. 4-hi mills, which have a smaller work roll, are used for more precise gauge control on thinner material. However many other factors come into play such as the horsepower, torque, and roll separation force of the roll housings. That is why some 2-hi rolling mills with polished rolls, for example, are perfectly suitable for creating the shiny very light gauge gold and silver used in the jewelry industry. Another important feature of any rolling mill is the type of screwdown. With each successive pass through the rolling mill the thickness of the material is reduced. The rolls themselves then must be closed tighter for the next pass to roll thinner. This is accomplished by the screwdown. Screwdowns can be manual, such as a large handwheel turned by the operator, or they can be motorized, or they can be hydraulic. Screwdowns can also be tied directly to thickness gauges so that the rolls will be automatically raised and lowered hundreds of times per second on a mill running at 2500 feet per minute with an automatic gauge control (AGC) system. There are many other things to consider in selecting the correct rolling mill for the application, such as the tensile strength of the metal being rolled or the amount of tension between the rolls and coilers which are beyond the scope of this article. Rolling is a complicated business for what appears to be the simple task of reducing the thickness of metal. 4
January 2019
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About the Author: John Conroy is Chairman of Machinery International Corporation. John received a Bachelor of Arts Degree in Political Science from the University of Notre Dame in 1972. He served in the Pacific as a Surface Warfare Officer in the U.S. Navy for four years followed by an additional year as an instructor at the U.S. Naval Officer Candidate School in Newport, Rhode Island. He received his law degree at Boston College and became a mergers and acquisitions specialist in Boston. John was President of the Machinery Dealers National Association from 1993 to 1995 and has served on both its Board of Directors and Executive Committee continuously for over 25 years. He has also served as MDNA Convention Chairman for the past 20 years and is the recipient of the Randolph K. Vinson Award and the MDNA Lifetime Achievement Award. He is married to Kristine McMillan Conroy, who is President of the MDNA Austin D. Lucas Scholarship Fund, and they have two sons, Adam and Austin. John and his business partner, Steve McMillan, began Machinery International Corporation in 1993, but its roots can be traced back to the 1960s with its predecessor McMillan Machinery Company. The company specializes not just in rolling mills but in all equipment for the production of metal strip, tube, wire and rod. The company has its office and warehouse in North Branford, Connecticut, but the majority of its business is offshore using a network of agents combined with hundreds of machines in inventory located worldwide.
20 Commerce Drive North Branford, CT 06471 USA Tel: +1 203-484-0400 Fax: +1 203-484-4499 sales@machyintl.com Machinery for the Strip, Tube, Wire and Rod Industries including Rolling Mills, Levelers, Slitters, Swagers, Extrusion Presses, Wire and Tube Drawing Machines, Cut-to-Length Lines, Melting and Casting, Straighteners, and Much More!
www.machyintl.com
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January 2019
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Liquidation of Complete State of the Ar t 1600mm Stainless Steel Cold Rolling Facility All Assets Installed in Duesseldorf, Germany
Featuring Equipment: -
1600mm SMS Demag ZR21BB-64 Sendzimir Cold Rolling Mill, Stk# 112926 1300mm SMS Demag ZR22-52 Sendzimir Cold Rolling Mill, Stk# 112925 1600mm Schloemann 2hi Reversing Skin Pass Cold Rolling Mill, Stk# 112935 1300mm Krupp 2hi Reversing Skin Pass Cold Rolling Mill, Stk# 112957 1320mm SMS Schloemann 4hi Reversing Cold Rolling Mill, Stk# 112947 1300mm General Electric Bright Annealing Line, Stk# 112948 1300mm Drever Bright Annealing Line, Stk# 112951 1600mm Sundwig Hot/Cold Annealing Pickling Line, Stk# 112949 1300mm Sundwig Pickling Line, Stk# 112950 1600mm Sundwig/Acme Murraway Coil Grinding Line, Stk# 112960 1600mm x 6mm x 29 Ton Sundwig Stainless Steel Slitting Line, Stk# 112952 1300mm x 2.5mm x 26 Ton Sundwig Stainless Steel Slitting Line, Stk112953 1350mm x 1.5mm x 27 Ton Sunwig Stainless Steel Slitting Line, Stk# 112954 1300mm x 2.5mm x 24 Ton Ungerer Stainless Steel CTL Line, Stk# 112956 600mm x 2mm x 13 Ton Ungerer Stainless Steel CTL Line, Stk# 112955
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ills a M g n i l l o R ers in
Lead
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litie i c a F l l i M Rolling
Roll Grinders: Andritz Lynson V 330 CNC (New 2005), Andritz Lynson V 645 CNC (New 2006), Dehn Automat/Schmaltz CNC, Naxos Union W1400, (3) Naxos Union W500 Roll Grinders, Naxos Union W400 Roll Grinder, Schmaltz WR4/2000 Plant Support and More
For more information please contact our office +1.973.344.6100 or sales@nationalmachy.com 6
January 2019
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