Rolling mills — configuration of a two-high stand In metal rolling practice, a two-high rolling mill uses two work rolls mounted one above the other. For such a mill, the two rolls are typically of what relative size?

Introduction / Context:
Rolling mills reduce thickness by passing metal stock between rotating rolls. A two-high rolling mill is the simplest stand arrangement and is commonly used in primary breakdown and in reversing mills. Knowing the relative size of the two rolls helps learners understand load sharing, deflection, and bite conditions.

Given Data / Assumptions:

• Configuration: two rolls in a single stand, one above the other.
• Objective: identify the typical relative size used in industry teaching and exams.
• Consider standard, non-specialized hot or cold rolling of strips/plates/blooms.

Concept / Approach:
In a conventional two-high mill, the two work rolls are made with the same nominal diameter and face (barrel) length so that contact geometry, flattening, torque, and power transmission are symmetrical. Equal size simplifies bearing, chock, and drive design and allows reversing operation without changing contact conditions.

Step-by-Step Solution:

Verification / Alternative check:
Shop layouts and textbooks show two-high reversing stands with matched roll diameters. Any crown (barrel camber) is a subtle profile modification, not a diameter mismatch between rolls.

Why Other Options Are Wrong:

• Different or stepped rolls: used in some special mills (e.g., cluster/Sendzimir) but not in basic two-high stands.
• Different barrel length: would limit product width and create edge defects.
• Crowned upper/flat lower only: crown is applied to both rolls to counter roll bending.

Common Pitfalls:
Confusing two-high with four-high or cluster mills where backup rolls differ from work rolls. Also, mistaking crown (a slight barrel convexity) for different roll diameters.

Final Answer: