Automatic Storage Systems for Heavy Lloads

The automatic storage system is defined heavy if the load unit it moves weighs more than 500 kg. The majority of heavyweight automatic storage systems have load units weighing between 1,000 and 1,500 kg, but can accommodate weights of 3,000 kg and over.In this type of storage system the load units are usually wooden pallets or metal cases but special load units are often used, specific for the goods contained, such as the coil cradles. Usually the loads are retrieved by means of telescopic forks that operate in single, double or triple depth. The storage systems for heavy loads are characterised by very sturdy stacker cranes. In the majority of cases translation is performed by means of a pair of metal wheels, at least one of which is motorised. The load unit is lifted by means of chains or steel ropes. The stacker cranes for heavy loads can be provided with operator cab , useful in the case of inspection and maintenance, in particular when operating at a height. Although not at the same level as the storage systems for light loads, these automatic storage systems nevertheless perform well. The translation speed is usually 3 m/s with a lifting speed of 0.6 m/s, often reaching or exceeding 1 m/s.

Multi-Depth Automatic Storage Systems

The multi-depth feature can be applied to storage systems for both heavy and light loads and is used to increase storage density.In the multi-depth storage systems the load unit can be positioned in front of others already stored in the system. In this way the full depth of the "channels” is utilised with load unit management according to different systems depending on the solution adopted. More specifically, management will be according to the FIFO (first in – first out) system in the case of gravity-fed systems and according to the LIFO (last in – first out) system in the case of push-back or shuttle systems. Cases of double and triple depth are not typical, and are controlled by simpler systems; in the real multi-depth systems, the channels can contain from 4 to 15 load units each.In these cases very high storage density is obtained because the wasted space, i.e. the passage for the stacker crane, represents a small percentage with respect to the space allocated to storage. In the shuttle systems each shelving channel is provided with guides on which a shuttle moves, inserted by the stacker crane in the required channel: the shuttle runs along the channel to the point where the load unit has to be retrieved or deposited.In addition to the above shuttle systems and gravity-fed systems, Armes, with its company Promag, also holds a special patent for production of the UPB storage systems: the dynamic system UPB (Under Pallet Base) takes its name from the bases, provided with special rollers, with which each load unit is provided. A pair of rails is positioned in each channel, sloping in the direction of the corridor, into which the stacker crane pushes (push-back system) the UPB bases, one after the other. When the stacker crane retrieves the first UPB of the channel (LIFO system), those behind drop down by gravity. The UPB system is particularly suitable for handling special types of load unit, as in the case of reels and coils which are difficult to manage with traditional systems. In the multi-depth systems the system supervision software plays a very important role, as it must be able to optimise storage and retrieval to avoid unnecessary movements due to internal shifting for rapid access to the required load unit.

Multi-Depth Automatic Storage Systems

The automatic storage systems are storage systems in which the deposit and retrieval operations are performed by a computer-guided robot: the stacker crane. The stacker crane is a three-axis machine (i.e. it performs three types of movement: translation in the corridor, upward movement and deposit/retrieval of the load unit) which moves inside the shelves ? in the corridor ? and is guided by rail. The distinguishing feature of the corridor with respect to the corridors of the traditional storage systems is its narrow width, practically equal to the depth of the load unit. The automatic storage systems can be produced with one or more corridors depending on storage requirements. In the case of several corridors, the most common configuration is one stacker crane per corridor but systems are also produced in which one single stacker crane serves several corridors. In this case, steering stacker cranes are used (which, via points systems on the rails, can switch from one corridor to another) or transfer bridges (shuttles that transport the stacker crane from one corridor to another). Systems of this type are used when a large storage capacity is required for low rotation goods. According to requirements, storage can be single, double or multiple depth (see connection below for details), and the stacker crane can transport one or more load units simultaneously. In addition to permitting very high density storage, the automated systems have the advantage of reaching considerable heights that are impossible to reach with traditional storage systems. Building regulations permitting, heights well over thirty metres can be reached without difficulty. Many of these systems areself-supporting, i.e. the shelving supports the side walls and the roof. This offers considerable savings as there is no longer the need for a building to contain the automatic storage system, as the storage system itself constitutes the building. To integrate the storage functions (shelf and stacker crane), the automatic storage system is completed by a set of conveyors which, according to requirements, move the goods from and to the stacker cranes, perform picking operations (both manual and robotised) or connect the automatic storage system with the production lines or with the loading bays of the shipping department.