1 year ago

MDA Technologies 5/2015

MDA Technologies 5/2015


MACHINE ELEMENTS 01 The ‘Roba-stop-silenzio’ dual circuit brakes in the stage winches are essential for the smooth operation of the cable robot systems 02 A total of 16 linear winches by ASM Steuerungstechnik GmbH, drive the bee‘s eyes at the show, live in German Pavilion The requirements for the show in the German Pavilion, rise over and above this. The bee’s eyes require, in addition to the four cable winches required for movement in an X, Y and Z direction, four additional winches to be installed for the realisation around the three axes. This makes it possible to move the bee’s eyes not just horizontally and vertically within the room, but also to turn and tilt them sideways by up to 30° around the X, Y and Z axes. In total, the two cable robots with the bee’s eyes are therefore driven by eight linear winches. The winches have been dimensioned for a nominal load of 2.4 kN and can be operated at a maximum speed of 1.2 m/s. The working spaces of the bee’s eyes do not overlap – thus preventing the possibility of collisions. The control software for the calculation of the trajectories for the two cable robots originates from the University of Stuttgart; the official research partner for the German Pavilion. Endurance capability for 40 shows per day Due to its construction, the system is very lightweight, and the forces, which are incorporated into the building through its use, are almost negligible. All the cable winches are mounted onto the building structure of the show room. However, each image unit weighs approx. 130 kg – during the flight over the heads of the visitors, maximum operational and functional safety must therefore be guaranteed. The safety brakes in the winches assume a responsible task. They ensure that the bee’s eyes do not drop uncontrollably and thus reliably prevent injury to people or damage to property at all times. The show demands maximum performances from the brakes. A total of 7,500 shows, approximately 40 per day, have been planned over the entire Expo runtime. Reliable safety for people The electromagnetic safety brakes are each directly installed in the 16 cable winch gears, with a braking torque of 2 × 100 Nm. They work as spring applied safety brakes, meaning that they close once the power has been switched off. The brakes therefore stop the bee’s eyes reliably even in case of power failure or emergency stop. The two brake circuits, which work independently of each other, ensure a high level of operat- About Company name: Chr. Mayr GmbH + Co.KG Headquarters: Mauerstetten, Germany Employees: approx. 1,000 worldwide Products: Safety brakes, clutches and couplings ing safety. The brakes are equipped with an inductive proximity sensor especially developed for Mayr safety brakes. This contactless release monitoring prevents unpermitted operating conditions such as the motor starting up against closed brakes. In addition, the contactless system is absolutely reliable, is wear-free and resistant to magnetic fields. Smooth, soundless flight The ‘Roba-stop-silenzio’ brakes from Mayr, are equipped with a special noise damping system. They generate almost no switching noise, and in new condition, the noise levels lie below 50 dB(A) (sound pressure level measurement). Long-term testing has confirmed that the extremely quiet opera tion is retained even after 300,000 switchings. Even after several million switchings, the switching noise level remains substantially below that of other stage brakes. The system has been accepted by two experts commissioned by the State during test construction in Germany, and after installation and commissioning on-site in Italy. Photographs: Mayr power transmission, Milla & Partner / Schmidhuber / Nüssli, ASM Steuerungstechnik GmbH MDA Technologies 5/2015 21

MACHINE ELEMENTS Reliable connection for offshore gangways – with double row slewing bearings Ulrich Schroth On offshore facilities, safety is the greatest good. Gangways are a crucial safety element in offshore facilities. Double row ball slewing bearings provide smooth movement in the supports of offshore gangways – also under the harshest conditions. Author: Ulrich Schroth is Product Manager Precesion Bearings at Rodriguez in Eschweiler, Germany Offshore gangways enable transport of the personnel from the ship to the platform and back. They are also used as a bridge for lines carrying fuel, electricity or water. Optionally they serve as a link between a fixed and a floating installation or between two floating installations. Modern telescoping offshore gangways compensate ship movements in all directions. If these movements exceed a critical level due to waves, the safety of the personnel is no longer guaranteed. The gangways are therefore designed so that they automatically rise and retract in such a case. In order to facilitate installation on the bow or side of smaller ships the gangways have to be lightweight and compact. Resistance to saltwater is also an absolute prerequisite. Hence they are manufactured from aluminum. The material is lightweight yet has the stability to withstand the harsh conditions. Custom components for harsh conditions One end of the gangway is permanently installed on the ship or the offshore platform. Movement around the rotating axis is ensured by double-row slewing rings from Rodriguez GmbH. These components have to withstand the harsh conditions: very low temperatures due to use in Arctic waters, corrosive saltwater environments and enormous overturning torques of the gangway place special requirements on the


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