Dans les laminoirs d'acier modernes, incidents inattendus, comme un bris de barre, désalignement du guide, ou blocage des rouleaux : peut causer de graves dommages à l'équipement en aval s'il n'est pas résolu immédiatement.. Pour atténuer ces risques, des dispositifs de sécurité spécialisés sont installés aux points critiques de la chaîne de production. Parmi ceux-ci, le cisaille volante pour les accidents joue un rôle essentiel dans la protection des machines de grande valeur telles que les usines de préfinition et de finition. HANI Intelligent Products a développé un robuste, solution fiable conçue précisément à cet effet.
Qu'est-ce qu'une cisaille volante en cas d'accident?
Souvent appelée cisaille à coupure d'urgence ou cisaille à préhension, ce dispositif est stratégiquement positionné entre les cages de pré-finition et de finition dans un laminoir à chaud de bandes ou de barres. Sa fonction principale est simple mais essentielle: pour couper instantanément la barre d'acier chaude entrante en cas d'urgence, l'empêchant de pénétrer dans les équipements sensibles en aval.
Contrairement aux cisailles volantes conventionnelles utilisées pour la coupe en longueur, ce type de cisaille n’est pas conçu pour une coupe de précision, il est conçu pour la vitesse, fiabilité, et interruption par force brute. Lorsqu'un défaut survient en amont (par ex., une barre cassée faisant une boucle dans le moulin), le système se déclenche en quelques millisecondes, serrer et déchirer la billette en mouvement en utilisant sa propre énergie cinétique.
Comment ça marche: La simplicité rencontre l'efficacité
La conception suit une double lame, mécanisme en forme de ciseaux:
- Une lame est montée au-dessus de la ligne de laminage.
- The other is positioned directly below.
- Both blades remain retracted during normal operation to avoid interference.
- Upon emergency signal, a pneumatic cylinder actuates, driving a linkage system that forces both blades to close simultaneously onto the moving bar.
Surtout, the shear doesn’t rely on sharp cutting edges alone. Plutôt, it exploits the high-speed motion of the hot steel (typically traveling at 5–15 m/s). As the blades clamp down, the bar’s forward momentum generates immense tensile stress at the pinch point, causing it to fracture cleanly—a process known as “tearing by self-propulsion.” This method eliminates the need for massive hydraulic force or complex synchronization.
Principales spécifications techniques
HANI’s flying shear for accident protection is engineered for harsh mill environments. Below are verified performance parameters based on real-world installations:
| Paramètre | Valeur / Gamme |
|---|---|
| Applicable steel grades | Carbone, acier faiblement allié (par ex., Q235, SS400, SAE 1045) |
| Operating temperature | >950°C (typical exit temp from roughing mill) |
| Pneumatic cylinder size | Φ100/Φ32 × 240 mm (double-acting) |
| Air pressure requirement | 0.4 – 0.6 MPa (standard plant air supply) |
| Response time | ≤ 0.3 seconds from signal to full closure |
| Max bar speed at shear point | Jusqu'à 12 MS (depending on mill layout) |
| Frame construction | Welded steel base with stress-relieved structure |
Fonctionnalités de conception importantes dans les opérations réelles
Field experience shows that reliability under extreme conditions is non-negotiable. HANI’s design incorporates several practical enhancements:
Structure mécanique robuste
The entire assembly sits on a heavy-duty welded base, minimizing vibration and ensuring alignment stability over years of thermal cycling. The shear body uses hardened tool steel for blades, with replaceable inserts to reduce maintenance downtime.
Stratégie de lubrification intelligente
To survive in a high-heat, high-dust environment, the system avoids complex oil circuits. Plutôt:
- Pivot points on the blade arms use sintered bronze oil-impregnated bushings—maintenance-free for thousands of cycles.
- All other joints (linkages, pins) are fitted with grease nipples for manual lubrication during scheduled stops.
This hybrid approach balances longevity with service simplicity—no pumps, filters, or leak-prone lines.
Actionnement pneumatique: Pourquoi l'air plutôt que l'hydraulique?
While hydraulic systems offer higher force, they introduce complexity: oil leaks, temperature sensitivity, and slower response in cold starts. En revanche, plant-compressed air is already available throughout most mills. Using a standard Φ100 cylinder at 0.5 MPa delivers ~3,900 N of thrust—more than enough to clamp a red-hot bar when combined with mechanical leverage. Plus, air systems reset faster and pose no fire risk near hot steel.
Installation & Conseils d'intégration
For optimal performance, consider these field-proven guidelines:
- Positionnement: Install 1.5–2 meters upstream of the first finishing stand. This provides enough clearance for the severed head-end to drop safely without jamming.
- Alignement: Ensure the shear centerline matches the rolling axis within ±1 mm. Misalignment causes uneven blade wear and incomplete cuts.
- Control Logic: Integrate the shear trigger with multiple fault signals—e.g., motor overload, loop detector activation, or emergency stop buttons. Use redundant sensors to avoid false negatives.
- Cooling Protection: Shield the cylinder and linkages with refractory curtains or water-cooled jackets if ambient radiation exceeds 150°C.
Liste de contrôle de maintenance pour une fiabilité à long terme
Even the toughest equipment needs care. Follow this routine:
| Task | Frequency | Remarques |
|---|---|---|
| Inspect blade wear | Hebdomadaire | Replace if edge chipping >3 mm or gap >1 mm when closed |
| Lubricate pivot joints | Chaque 2 weeks | Use high-temp lithium grease (NLGI #2) |
| Check air filter & regulator | Mensuel | Drain condensate; verify pressure stability at 0.5 MPa |
| Test emergency trigger | Trimestriel | Simulate fault signal; confirm full closure within 0.3 s |
When properly maintained, this system can operate reliably for over 5 years without major overhaul—providing peace of mind and significant cost savings by preventing catastrophic mill damage. In one documented case at a 600,000-ton/year bar mill, the installation of HANI’s flying shear for accidents reduced unplanned downtime by 18% in the first year alone, primarily by avoiding roll pass destruction during bar breaks.
For mill engineers and operations managers, investing in a well-designed emergency shear isn’t just about hardware—it’s about building resilience into the production line. And in an industry where every minute of downtime costs thousands, that resilience pays for itself many times over.
