Heat and dust: energy supply system for indoor crane under adverse conditions

Profile

• What was needed: Pre-assembled energy chains for use in a Heavy Duty application
• Requirements: Tight installation space, resistance to high temperatures and heavy contamination, trouble-free operation
• Field of application: Steel industry
• Success for the customer: Quick assembly on the crane bridge by delivering the filled e-chains® on transport drums. The very compact chains also do not have to be dismantled or packed for onward transport to the place of use.

A double-girder gantry crane in Thyssen Krupp's Duisburg hot rolling mill takes the freshly produced slabs, which are subsequently processed into steel strip, stores and retrieves them and feeds them to the heat-retaining furnaces. It travels at up to 120 m/min on the 500-meter-long crane track. In trolley drive, speeds of 60 m/min are achieved, whereby the crane operator can move the cabin over almost the entire length of the bridge. For reasons of space (the installation space is limited at the top), the entire control system had to be housed in the bridge rather than in an external control room, so that the trolley does not travel above but between the two bridge girders.  Furthermore, all components used must be designed for heavy duty operation. The crane is constantly exposed to large amounts of dust and high temperatures. The slabs and the hot holding furnace emit so much heat that temperatures up to 70°C are reached even just below the ceiling of the hall.  Accordingly, the movable cables for electrical energy and signals as well as the energy chains must be designed to cope with the adverse conditions in order to ensure trouble-free operation under the extreme conditions.

In view of the requirements, the igus® technicians recommended a roller e-chain® of type 5050RHD for the energy and signal supply on the crane bridge. The chain system used for "heavy duty" applications is characterized by reinforced side parts, additional wear surfaces and a pin-hole system that has been reinforced by about 40 percent. As a result, cable weights — in this case 13 kg/m — can be guided and moved reliably. The chain length in this case is 17.8 m, with the system travelling a distance of 15.5 m. In addition cables of the chainflex® product range from igus® were used. A TPE jacket ensures that all cables can withstand the high temperatures in the system.

Based on the special requirements for energy chain and cables, the chains were designed and supplied as pre-assembled readychain® basic systems.  The cables have been inserted but have not been completely pre-assembled or fitted with connectors. Plug-in connectors are unnecessary because the cables are connected to terminals. In addition, the cable lengths for such a special project cannot be determined down to the centimeter. Flexibility is more important in the assembly. Only the fiber optic cables (FOC) were harnessed with connectors in advance.