Process and apparatus for producing high reduction in soft metal materials

A process for reducing the thickness of a strip material, said process comprising:

• providing a rolling mill having at least two driven back-up rolls and at least two offset idler work rolls, each of said back-up rolls and said work rolls having an axis of rotation;
• orienting said back-up rolls so that said back-up roll axes of rotation define a first plane;
• orienting said offset work rolls so that said work roll axes of rotation are positioned on opposite sides of said first plane and define a second plane at an angle to said first plane;
• passing said strip material through a roll bite defined by said offset work rolls in a desired rolling direction to effect a desired gage reduction in said strip material thickness;
• applying a compressive force having a desired magnitude to said rolls to effect said desired gage reduction;
• and
• driving said offset work rolls forming said roll bite at a peripheral speed ratio less than the gage reduction but greater than zero and thereby creating a first resultant frictional force in said rolling direction which at least partially drives said strip material through said roll bite and reduces the magnitude of the compressive force needed to obtain said desired gage reduction, said driving step comprising driving said work rolls with respective ones of said driven back-up rolls.