Planning an indoor crane takes a lot of experience. And if the available space is very scarce, it is worthwhile to partially outsource design tasks to suppliers. This applies in the present case to the energy supply system for a fully automatic crane facility. A solution was created from standard and special parts, which proved its worth in heavy duty use and in continuous operation from the very first day.
"Our strengths are customized crane facilities that are produced on site with pure manual work," explains Werner Herz from Kranservice Herz in Merkers, Thuringia. "As the structural conditions are sometimes very limited, space-saving energy supply systems play an increasingly important role. e-chains® replace festooning here, because the latter are always in the way due to the loosely hanging cables. “
Power supply for the rotating mechanism. The energy supply system mounted on the side with reversed bending radius is clearly visible.
The specialist developed a stacking crane facility for a renowned manufacturer in the metalworking industry. Preassembled "readychain®" e-chain systems® from igus® GmbH in Cologne play an important role here. The energy supply systems guarantee the required plant availability. The "basic" option was chosen here, i.e. assembled e-chains® with inserted cables, labeled and with defined projecting lengths according to customer specifications. Standard and special troughs are included in the delivery. The entirely ready-to-install energy supply system only has to be attached and connected to the crane.
The company Kranservice Herz was established in 1990 and transformed from a pure crane service provider into a producer of customized crane solutions. "Our specialty is project work. With around 18 employees we mainly build bridge and gantry cranes up to a lifting capacity of 100 t and span widths of up to 40 m. Our special strength here is flexibility," says company owner Werner Herz.
A main pillar of the company is the development of fully automatic crane facilities. Their application ranges from scrap package loading facilities in the automotive industry over bulk cargo loading cranes in the plaster and cement sector up to fully automatic stacking cranes. "In such an automatic crane facility for loading stainless steel pipes, we encountered very special ambient conditions," reports the son, André Herz. "Due to the structural conditions on site, the operator demanded an extremely low installation height. The space between the upper edge of the rail to the interfering edge of the mobile shelving system is only 1,000 mm, so the entire stacking crane facility had to be adjusted to these extremely narrow space ratios. “
Fully automatic stacking crane system by Kranservice Herz. The energy supply system is provided by specialist igus® GmbH as preassembled "readychain®" system.
In the shelves, bundles of pipes are automatically stored and transferred and saved in a warehouse management program. A total of 24,000 store and transfer processes take place each year. To feed the automated processing machines in the hall, the required pipe types are placed by the crane in a corresponding bar feeder of the processing machine. If there are pipe stocks still remaining in this magazine, they have to be first placed by the crane in the mobile shelf and automatically stored. The pipe bundles always vary in their dimensions and numbers. In the automated processing machines the pipes are then bent, turned and punched and prepared for further processing. The ambient conditions are accordingly difficult: oily air stresses the material in addition. "The initial situation was not easy," remembers André Herz. "Every shelf space means money. Many shelves are crammed into a narrow space. The crane travels over the shelves in a very narrow lane. Added to it are the quick turnaround times as well as the low installation height of the hall with regard to the upper edge of the mobile shelf. " Storage and retrieval units for high-bay warehouses would not have been appropriate with these structural conditions. They cannot directly feed the automated processing machines. Personnel is required. And first of all, the total storage capacity would be drastically reduced.
The structural installation height of the crane girder with a span width of 27.5 m, the trolley, the rotating mechanism and the rigid load guide should not exceed the previously mentioned 1,000 mm. "To find a suitable solution here, we had to find entirely new design approaches," recounts mechanical design engineer Marko Jacob. The company developed a so-called interlacing method. This means, the trolley with the trolley lane was installed between the crane bridge girders, and the rotating mechanism was constructed in such a way that it could be accommodated in the trolley frame without exceeding the height dimension - the upper edge of the crane bridge girders.
The power supplies for the trolley travel and the rotating mechanism proved to be another challenge. The available space for the trolley power supply was only 500 mm high and 300 mm wide. "Due to the low installation height, traditional festooning or conductor lines were out of the question from the start," explains André Herz. "Only energy supply systems designed in close collaboration with igus® were feasible. The entire cabling of the main power supply for the drives, control cables and the profibus cable is guided through it. And to make them smaller, they were split in addition. “
Two horizontally arranged e-chains® in counter direction are used for the trolley power supply. They lie laterally on the inside of the main girder above the trolley frame. This constructive arrangement does not exceed its upper edge. The travels of the trolley power supply are 21,245 mm in the first, and 17,650 mm in the second facility. The speed is 0 to 60 m/min. For the power supply of the rotating mechanism, another two horizontally arranged igus® e-chains® in counter direction are used. This system achieves a rotation angle of 270°. The speeds are 0 to 4 U/min. "I was doubtful initially. Due to the high loads we have to have reserves in all details," remembers Werner Herz. "The horizontal alignment of the rotating mechanism in particular was new for us. We knew only one thing: As we could not provide more space, there was no alternative to the e-chain®. “
Today the crane has an availability of 96 percent. It runs fully automatic 24 hours, seven days a week. "Our experiences with the energy supply systems from igus® are more than good," says Werner Herz. "The crane facility now operates for nearly two years. Until today no noteworthy failures have occurred. " And due to the good overall plan and the high reliability, a second facility has already been ordered and will start its operation in early 2009.
Demanding: Horizontal arrangement of the rotating mechanism. The space for the e-chain® is narrow and the air contains oil particles.
The four-piece e-chain® of the "E4/4" system from igus®, Series 3838, is used. Rugged and with modular design, it is particularly suitable for side-mounted applications. "In both projects the close collaboration has been proven and tested," tells André Herz. "We provided the basic technical data and were presented with a suitable solution that is in operation without problems every since. " Besides the preassembled "readychain®" energy supply systems, the complete trough material is supplied. They include standard troughs for the e-chains® in the gliding application as well as special troughs for the chains with reverse bending radius.
Thanks to the e-chain® solution, Kranservice Herz was able to create 50 percent more storage space. 30 percent due to the mobile shelf solution and 20 percent due to the low installation height of the crane. "We generally aim to support our customers even during the project planning stage," explains Yve Kirsch, consultant for technical applications with igus®. "We do that by preparing drawings and checking installation dimensions. Outside our standard product range – e-chains® and cables – we can complement system solutions with special parts. This does not only include special troughs. We rework e-chains® according to customers' specifications or even manufacture them to cover the respective application. “ Senior director Werner Herz couldn't agree more: "Our customer is very satisfied with his crane facility. His requirements are met. And I am sure that energy supply systems will increasingly establish themselves in hall cranes, not only for the reason of space. “
Rugged e-chain system® "E4/4" from igus® for the energy supply of the trolley.