The collaboration between skf industries and gaspari menotti, a perfect example of the integration of specialist skills, has brought about the design of a “long life” bearing, with self-propelling origin, to apply to the idle pulleys without needing lubrification.
From the beginning, guiding precision of the pulleys and reliability were the most difficult challenges in the designing of the GMW.
The operating system, guide and tensioning of the diamond wires, as the engineer Mr Roberti explains, requires the use of 140 ball bearings, plus another 70 that hold the tension pulleys of a smaller diameter, operated singly by a hydraulic actuator and staggered on two shafts. Considering the inevitable games in the axial space of about 20mm, a bearing with cage, rolling elements, two rings and seals must all find a place. (...) All in a hostile environment, characterized by the presence of water mixed with granite powder. Moreover, the presence of hundreds of lubrication points, constituted a major source of costs and an intrinsic limitation to the reliability of the system.
It was a real design challenge for SKF, who had to find a solution for the bearings that support the idle and tensioner pulleys and able to integrate three main functions: protection from contaminating agents, correct lubrication of the bearings and the correct load capacity and positioning accuracy.
The result of this highly technological collaboration was the creation of a special bearing, characterized by combining the pulley with a permanently grease lubricated flange, using technology that is already used for car wheels.
(Excerpt from "Granito cut by wire" published on Organi di Trasmissione, June 2010).
Franco Roberti, Managing Director of Gaspari Menotti (right) and Victor Lucotti, Southern Europe Marketing and Communications Manager of SKF Industrial Division, discuss some technical aspects of the new bearing.
"Organi di trasmissione " No.6, June 2010
Model of the Bearing Unit for a tensioner pulley
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