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Twist-proof energy chains for vertical order pickers

Torque-resistant cables for vertical order pickers of up to twelve meters

chainflex® Power and signal cables prevent corkscrew when supplying the mast.

Profile

What was needed: resilient energy and signal cable via movable lifting frame with several deflection rollers to the cabin of an order picking device
Requirements: Space-saving guidance of the electrical and hydraulic cables, application in the deflection principle with long cable lengths
Product: chainflex® cable
Area of application: forklift, tractor and order picking devices
Success for the customer: durable cable solution for demanding geometry of mast and return pulley

Verticalorder pickers: The vertical order pickers of the EK-X series are particularly impressive in Still's wide range - the Hamburg-based company is part of the Kion Group, which in turn is the second largest forklift manufacturer in the world with a turnover of almost 4.5 billion euros (2013). Their task is to approach the pallets from which the driver removes individual cartons in the narrow aisles of a high-bay warehouse. The order pickers reach picking heights of up to twelve metres and can be perfectly adapted to the individual application thanks to the modular design principle. For example, the buyer can choose from different cabs, lift masts, control panels and battery systems, and customised options can also be realised.

The challenge

Still already uses the deflection principle for cable routing in smaller order pickers and it has proven its worth. For the EK-X series, the lateral guidance of the roller was improved somewhat due to the longer cable lengths - and then the first tests quickly showed that this solution unfortunately does not work here. Volker Haspel, responsible for electrical development at Kion Systems: "The cables that we normally use twisted and looked like a corkscrew. Shortly afterwards, they failed in the test. Testing such cables is a complex task in itself. They perform relative movements in the lifting frame and the movement of the order pickers is highly dynamic. You also have to take into account the tensile force that occurs here in contrast to energy chain cables."

Solution

The tests in the laboratories of both companies showed that the special chainflex® cable structure with bundle stranding also holds very well on the rollers. The cores are first stranded into bundles, which in turn are stranded around a core element with a small pitch length. This core element not only serves as a filler, but is also designed as a strain relief element. The result is very reminiscent of a steel cable. To provide additional support for this stable strand structure, a jacket is extruded under pressure to guide the core in the longitudinal direction. All these measures have the effect of minimising the forces generated in the cable and maintaining the structure.

The special materials of the jacket and their processing also help significantly with durability. It has been shown that the shape of the pulley has no influence on the service life. This made the decision clear for the Still designers, and the cable was defined as the standard for the EK-X mast. A chainflex® cable with bundle stranding and TPE jacket is used, which is between 4.50 and 16 metres long in the order pickers. There is no question that they are subject to high loads. In many applications, the devices are in continuous use so that the mast is always in motion. The chainflex® cables move under these conditions just as they do in the many thousands of energy chain applications. Still has thus found a solution to a problem that arose due to the modified geometry of the mast and idler pulley. The cable specialists at igus® have also gained a new insight: They now know that their cables are not only suitable for chains, but also prove themselves in roller guides.