HPGRs, also known as roller presses, are used in Mauritania for the processing of iron ore. A roller typically consists of a base body (shaft) to which a roll body in combination with a wear protection system is attached. The surface of the roll bodies is subject to heavy abrasion during operation, so that regular replacement of the roll bodies is necessary.
Towards the beginning of 2019, the pair of worn out rollers arrived at our fabrication and service in Lauchhammer, Germany. Removing the worn out roll bodies is the first step in the reconditioning process. Based upon previous calculations, the roll bodies were detached from the shafts by means of inductive heating, with release of the roll bodies occurring due to a resulting difference in thermal expansion between the roll bodies and the shaft. The shafts were subsequently mechanically reworked and with the bearing seats being reconditioned using a flame spraying process.
After machining of the delivered brand-new roll bodies, the shrinking on the reworked shafts followed. Again, the roll bodies were heated in a specific and defined manner until the inner diameter of the roll bodies opened beyond the outer dimension of the shaft due to thermal expansion. The shaft was inserted into the roll body to create a frictional connection after cooling. The wear protection, made up of numerous tungsten carbide studs, was then applied, with these studs being glued into the surface of the roll body using a special adhesive.
Josephine Lehnert, TAKRAF Germany Project Manager had this to say upon finalizing the packing process of the refurbished equipment: “Sincere thanks to all colleagues involved for their great cooperation in the smooth execution of this project. With the successful completion of this order, a significant reference for the sale of TAKRAF roller presses and the service business has been achieved.”
A short video of this entire process can be viewed here: https://www.youtube.com/watch?v=LnXDvI630Uw
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