Direct Roll Gap Control (DRGC) measures the roll gap directly in the work-roll necks (DS/OS). The short signal path gives faster feedback to the AGC and more stable thickness—especially at heavy gauges and during the first pass, when dynamics are most challenging. The result is fewer transient oscillations at the head/tail, reduced wedge, and a higher thickness Cpk.
Why Heavy Gauges and the First Pass Benefit the Most
- Larger force variations. Thick plate and the first pass involve high reductions and force steps. Small measurement or control delays quickly balloon into large thickness errors. By measuring the gap where it actually occurs—in the work-roll necks—dead time is minimized compared with solutions that only see cylinder position or an exit gauge.
- Pronounced transients at head/tail. When the strip/plate enters and leaves the bite, load jumps occur. DRGC provides the AGC with an “early” and locally correct gap value, which damps over-/under-thickness at the beginning and end.
- Less wedge and lateral spread. At heavy gauges, lateral spread is more pronounced. A stable gap directly in the bite reduces wedge and improves subsequent passes.
How DRGC Changes the Control Loop
Traditional AGC can rely on indirect gap indicators (e.g., HAGC cylinder position). DRGC moves the measurement point to the work roll and shortens the signal path:
- Measurement: gap sensors in DS/OS (work-roll necks).
- Processing: signal → control system (AGC/HGC).
- Actuation: faster correction of gap/force.
The short loop reduces overshoot and lets steady state be reached more quickly after speed or load changes. The effect is most evident where the process nonlinearities are greatest—heavy gauge and the first pass.
Want to see how much Cpk lift DRGC can deliver in your first pass?
Book a technical review—we’ll simulate your current loop, estimate transient gains, and set up a data plan for “before/after.”