HAGC & AWC Hydraulic Capsules for Rolling Mills
CUSTOMISED PRODUCTS
The hydraulic capsules are special large-diameter, short-stroke hydraulic cylinders, designed to generate the high forces needed to apply the rolling load. Our hydraulic capsules allow seal friction to be calculated as the opposing force varies.
To do this, we have developed special software to be used with purpose-built test rigs.
HAGC and AWC capsules
Large bore, short stroke, seal friction calculated and tested
HOW IT WORKS
- HAGC (Hydraulic Automatic Gauge Control): the capsules mounted in the rolling stand apply the rolling load and continuously correct the gap between the work rolls, to keep the thickness of the strip constant.
- AWC (Automatic Width Control): the same principle controls the width of the strip in the vertical stands.
Inside the stand the capsules act on a closed control loop. A fast position loop keeps the commanded roll gap, and the thickness control trims the setting. The controller knows the mill modulus, that is how much the stand stretches under the rolling load, so it separates the true roll gap from the position returned by the sensors: the corrections stay fine enough to compensate stand stretch and roll eccentricity, the periodic error that shows up as thickness waves along the strip.
Short strokes, high forces and fast response: this is why seal behaviour is decisive.
WHY HYDRAULIC SCREW-DOWN
Hydraulic screw-down allows the roll gap to be adjusted during rolling and can be integrated with thickness measurement systems. Dynamic response and accuracy depend on capsule sizing, servo valves, sensors and control tuning; the choice over electromechanical screw-down must be assessed for each mill.
CONSTRUCTION FEATURES
Special large-diameter, short-stroke cylinders designed to develop very high forces.
Seal friction is calculated as the counter-force varies, using software developed in-house, and verified in custom-built test rigs. Design with FEM and fatigue analysis, material checks and testing are all carried out at Silvio Fossa S.p.A.
ADVANTAGES
- Accurate control of strip thickness and width
- Known and measured seal friction, useful for tuning the control loop
- Very high forces in a compact envelope
- Finer thickness tolerances and fewer off-gauge lengths along the strip
- Fast response to micro-corrections, thanks to the short stroke and the low moving mass
- Revamping of existing capsules from any manufacturer
APPLICATIONS
Hot and cold rolling mills for steel and non-ferrous metals. See our cylinders for metallurgy.
Technical data
| Type | Hydraulic capsules (large-diameter, short-stroke cylinders) |
|---|---|
| Use | HAGC and AWC rolling systems |
| Forces | High, for the rolling load |
| Seal friction | Calculated as the counter-force varies, with dedicated software |
| Testing | In custom-built test rigs |
| Control | Closed position loop with thickness, tension or mass-flow corrections |
| Retrofit | Replacement and revamping of capsules in stands of any make |
Frequently asked questions
What are HAGC and AWC?+
HAGC (Hydraulic Automatic Gauge Control) keeps the strip thickness constant by adjusting the position of the work rolls; AWC (Automatic Width Control) controls the width. Both use hydraulic capsules.
Why does seal friction matter?+
With short strokes and continuous corrections, friction affects control accuracy. Silvio Fossa S.p.A. calculates it as the force varies with dedicated software and verifies it in custom test rigs.
Can you rebuild capsules from other manufacturers?+
Yes. The Silvio Fossa S.p.A. revamping service covers cylinders from any manufacturer.
Does seal friction stay constant?+
No: it changes with pressure and temperature. We compute it over the whole force range, as the counter-force varies, and verify it in our test cages, so the control loop can rely on known values rather than estimates.
Why is the stroke so short?+
The capsules adjust the work-roll gap through small movements under load. Bore and stroke are sized for the required force and the mill's adjustment range; response also depends on the hydraulic circuit and control system.
Need a cylinder built around your application?
Tell us your requirements and our technical office will prepare a quote.