Automated Double-Tower Sheet Metal Storage System

A double-tower system is easy to misunderstand as “two single towers bolted together.” If that were true, cost doubles, footprint doubles, and the only gain is more storage—hardly a compelling proposition. Herochu’s Automated Double-Tower Sheet Metal Storage System is designed around the opposite principle: two towers, one shared lift mechanism, double the storage capacity with roughly one-third the additional equipment investment.

The physical layout consists of two parallel tower columns sharing a central lift mast. The front tower sits near the operator zone or AGV aisle, with a loading station and buffer positions at the base; the rear tower is pure storage. The lift travels between the front and rear columns rather than, as in a single tower, returning to ground level before each new retrieval. The difference shows up clearly in consecutive retrieval scenarios. Suppose three sheets from different levels need to be retrieved in sequence. A single tower’s motion sequence is “descend—grab—deliver—descend—grab—deliver.” A double tower can pre-stage the next sheet at the front buffer while simultaneously pulling the third from the rear column, overlapping motions and cutting the wait time.

The direct beneficiary of higher throughput is the high-mix production floor. A laser cutter running five or six sheet types per shift is not unusual; if every changeover leaves the cutting head waiting several minutes, the cumulative loss over a shift amounts to several missed sheets. Herochu’s double-tower front buffer can pre-store the most frequently used specifications, so while the lift fetches a new sheet from the rear column, the front tower already holds the next one. For configurations feeding two cutters, operator boxes are installed beside each machine, and the touchscreen switches the delivery target without walking back to the tower’s main control cabinet.

Technically, the double tower follows the Herochu tower family’s specification framework: sheet sizes covering 3015, 4015, 4020, 6015, and 6020 formats, layer counts adjustable from 8 to 13, per-level load of 3 or 5 tons, vertical lift speed of 9 m/min, and entry/exit speed of 12 m/min. These load and speed figures look similar to a single tower, but the selection logic for a double tower is not about peak parameters—it is about average cycle time during continuous retrieval. If a shop exceeds 60 retrieval events per day, or if one tower must serve both the laser area and the bending area, the shared-lift architecture of a double tower is more cost-efficient than purchasing two independent single towers.

A frequently overlooked detail is footprint. Two independent single towers placed side by side require maintenance access and safety clearance between them, so the actual floor width is often more than twice the tower body itself. Herochu’s shared-mast design compresses the gap between the two columns to a minimum, yielding a total width roughly 400mm less than two single towers side by side. In a plant where aisle space is already tight, that difference sometimes determines whether a proposal can be implemented at all.

ERP integration and inventory management match the single tower: real-time display of sheet dimensions, weight, and quantity per level, on-demand stocktaking, and data synchronization to the factory management system. What differs is capacity. A double tower’s larger inventory capacity serves shops with long-term material staging needs—stockpiling a batch of stainless steel for a major order, for example—without consuming additional floor space. For businesses that want to preserve staging flexibility without letting the warehouse eat into production area, this balance point is more practical than chasing “maximum capacity” in isolation.