Double-Tower Sheet Metal Storage Series – High-Density Automated Warehouse by Herochu

When sheet metal fabrication volumes exceed the capacity of a single vertical tower, many system integrators simply install two independent towers—doubling cost, floor space, and maintenance complexity. Herochu has taken a fundamentally different approach with its Double-Tower sheet metal storage series, a purpose-engineered solution that shares a single hoist mechanism while delivering twice the effective storage density of conventional twin-tower designs. This series is specifically optimized for smart sheet metal processing environments where both throughput and floor space are critical constraints.

The Herochu double-tower configuration consists of a front tower and a rear tower, arranged in parallel and served by one vertical lifting column. Unlike two separate single-tower units—each requiring its own hoist, drive motor, control cabinet, and safety system—the double-tower series centralizes all mechanical and electrical components. This reduces capital expenditure by approximately 35% compared to purchasing two independent towers, while also lowering ongoing maintenance costs because there are fewer moving parts. The shared hoist alternates between towers under software control, with intelligent queuing that prioritizes retrieval requests based on production schedules.

Each level in both towers supports either 3 tons or 5 tons, consistent with the broader Herochu product family. Standard specifications include 3015, 4015, 4020, 6015, 6020, and 6025 mm, with custom lengths available upon request. Floor count ranges from 8 to 13 per tower, meaning a single double-tower system can store up to 130 tons of sheet metal—equivalent to two full truckloads of 3mm mild steel sheets. The movement mechanism uses linear guide rails and chain drives, identical to the single-tower series, ensuring parts commonality across Herochu installations. Vertical lifting speed remains 9 m/min, while inlet and outlet speeds are 12 m/min.

A distinctive feature of the Herochu double-tower sheet metal storage series is the integration of functions for sheet separation and double-sheet detection. These are not optional add-ons but core components of the storage logic. When the hoist retrieves a sheet from a level, the system first applies a controlled air knife or mechanical separator to break any oil-induced adhesion between sheets—a common problem in stacked coated materials. Immediately after separation, dual inductive sensors verify that only one sheet has been lifted. If a double sheet is detected, the system automatically returns the material to its storage level, flags the event in the PLC log, and attempts retrieval from an adjacent level or the opposite tower. This sequence prevents catastrophic laser head collisions or press brake die damage that often result from double-sheet feeding.

The lower levels of the front tower incorporate a loading station and lifting mechanism, serving as a buffer storage zone for material pallets. This design decision is unique to Herochu. In conventional automated warehouses, the entry and exit points are fixed at ground level, forcing the hoist to interrupt its retrieval cycles whenever new material is added. By dedicating the front tower’s lower levels as a buffer zone, the double-tower series decouples loading operations from production retrieval. A forklift or overhead crane can deposit pallets into the loading station at any time. The lifting mechanism then transfers these pallets to an available buffer level, from which the hoist will later distribute them to optimal storage floors during idle periods. This buffer zone effectively eliminates operator-induced downtime.

Compared to two independent sheet metal storage towers, this configuration delivers superior cost efficiency for several additional reasons. First, the shared hoist mechanism reduces electrical and mechanical complexity. Second, a single control cabinet and PLC manage both towers, simplifying programming and reducing spare parts inventory. Third, the combined footprint is approximately 20% smaller than two separate towers because no service aisle is required between them. Fourth, installation time is shorter—typically four days versus seven days for two independent units. Fifth, energy consumption is lower because one motor moves the hoist instead of two.

Customizable bay heights allow the Herochu double-tower system to accommodate atypical sheet thicknesses or pallet designs. A compact footprint is achieved through close-coupling of the two towers and the elimination of redundant aisles. The modular design philosophy means the double-tower series can operate as a standalone sheet metal storage warehouse, feeding a single laser or punch press, or it can be seamlessly integrated with auxiliary equipment such as automatic loading/unloading cells, straightening machines, or edge deburring stations. For facilities with future expansion plans, the system supports the addition of a third tower or connection to a multi-column library.

Connectivity is fully expandable, with ERP/MES interfaces that support 24/7 continuous operation. The system’s internal database tracks not only each sheet’s location but also its time-in-storage, allowing automatic rotation of aged materials. Production managers can set rules such as “always retrieve oldest 5052 aluminum first” or “reserve level 5 for 0.5mm galvanized steel.” The touch screen control panel provides both a graphical warehouse map and a production queue display.

From a safety perspective, the double-tower series includes interlocked access doors, light curtains at the loading station, and a software-based anti-collision algorithm that ensures the hoist never moves while an operator is inside either tower. Emergency stop buttons are located at both ground level and the control panel. The chain drive system is fully enclosed to prevent pinch points.

In real-world installations, Herochu double-tower systems have demonstrated throughput rates of 40 to 60 sheets per hour, depending on storage depth and sheet size. For smart sheet metal processing workshops running two shifts or more, this series provides the density, reliability, and cost structure required to justify full automation. The combination of shared hoist design, buffer storage zone, and integrated sheet separation makes the Herochu double-tower sheet metal storage series one of the most technically sound investments in the material handling category.