Energy chains and cables for fail-safe storage and retrieval units from viastore

Profile user report

• What was needed: Energy chains, chainflex cables
• Requirements: Safety with fast stroke movements and vibrations, resistance to freezing
• Industry: Mechanical engineering, small parts storage and retrieval units (SRUs)
• Success for the customer: Savings of enormous  process costs and at the same time risk minimisation, because the components function perfectly, reliable and long-lasting solutions, which ensure high availability of the plant and keep maintenance costs low

viastore SYSTEMS plans and implements automated storage systems - ranging from small parts to pallet and shuttle warehouses - including storage and retrieval units (SRUs). These must work quickly and flexibly in order to be able to react to changing order cycles and quantities.

Problem

Within intralogistics, providers organise internal material flows by means of technical systems and software solutions. An elementary component here are automatic storage and retrieval units (SRUs), which move goods and store them in and retrieve them from the compartments of the high-bay racking.
Since 1970, the Stuttgart-based company viastore has been developing and producing storage and retrieval units for all types of warehouses, in all size and speed classes, and differentiates between three basic types according to travel speed and payload. The smallest system, "viaspeed", has been specially designed for plastic containers and cartons and for a payload of up to 50 kg. With a travel speed of 6 m/s and an acceleration of 3 m/s², it is highly dynamic. The SRU "viaspeed XL", on the other hand, picks up loads of up to 300 kilograms and transports containers and trays. It has a travel speed of up to 5 m/s and accelerates vertically at 2 m/s². The system can still be used at temperatures from minus 40 degrees Celsius to plus 45 degrees Celsius. Finally, the most powerful storage and retrieval unit, viapal, handles pallets, wire mesh boxes and other loads of up to three tons. The dynamic travel drive makes a travel speed of 3 m/s and a vertical acceleration of 1.5 m/s²possible.
These performances show that in all SRUs, whether small or large, the demands on the systems are very high. viastore offers solutions that are highly dynamic and flexible, allowing for increased number of retrieval and storage actions when the number of items and orders increases. Warehouse operators expect automated solutions to adapt to ordering processes and to respond faster to peak times. They also demand reliable and durable solutions that ensure high plant availability and keep maintenance costs low. Against this backdrop, it is crucial that all components in the units, such as the energy supply solution, also function superbly under precisely this high requirement profile and need to be maintained only rarely, if at all.

Solution

Today, these requirements are met by the maintenance-free polymer energy chains and chainflex cables from igus. They are installed in the lifting gear on the mast of the storage and retrieval units and supply the systems with energy and data like an umbilical cord. Especially the fast lifting movements and vibrations at large unit heights or at high travel speeds place an extremely high load on the cables. Conventional cables can often form corkscrews, which can lead to core breakage.
This is why igus began developing special cables under the brand name chainflex for dynamic use in energy chains back in 1989. A special feature is their specific structure consisting of cores wound in bundles. Here, the cores are not wound in layers around the centre of the cable, but are wound together in three, four or five cores, which are then wound together again to form a complete stranding of the bundles. Additionally, gusset-filling extruded inner jackets fill the spaces between the cores. The effect: The stranding cannot unravel and each core is moved equally in the inner and outer radius when moving in the energy chain. One-sided stretching and compression, which often lead to core ruptures or corkscrews, are a thing of the past.
But temperature-resistant cables are also important to viastore for use in deep-freeze warehouses. They have to cope with small bend radii and millions of strokes at very low temperatures. Not only the design principle but also the used materials qualify the cables for continuous use in this application. For example, in particularly cold ambient conditions, cables with specially developed highly cold-flexible TPE outer jacket materials are used.
But the variety of cable types in the igus range was also important to the customer. viastore can flexibly offer 1,244 chainflex cables – from control and servo cables up to motor and robot cables as well as bus, encoder and fibre-optic cables .

The maintenance-free e-chains and chainflex cables from igus are mounted in the lifting gear on the mast of the viastore storage and retrieval units and supply the systems with energy and data.

In the cold chamber at igus, cables can be tested at temperatures from -40°C to +60°C.