VMI-AZ Introduces Giant OTR Tyre Extrusion System
In September visitors to the OTR Retreading Conference in Epe, the Netherlands, were given a demonstration of the newest extrusion systems developed by the VMI Group’s extrusion division. These latest products to be developed by the German based division enable the retreading of giant OTR tyres and consist of two key components – the VMI-AZ Base Constructor and the Strip Builder.
The Base Constructor consists of three PIN-type Extruders attached to a retread extrusion head that supplies base rubber to the tyre carcass. This set-up smears rubber onto the tyre carcass while the carcass is rotating. Simultaneously, skive holes are filled and the shoulder is automatically built at the same time. The so-called cushion-to-casing technology is already employed in VMI-AZ retread machinery for truck tyres.
Once the Base Constructor’s job is done, the carcass is moved to the Strip Builder. This unit provides a hot extruded rubber strip that is supplied to the tyre carcass to build up the new tread according to a menu controlled pattern and shape. The strip is directly applied and compacted onto the carcass, avoiding any air entrapment.
The OTR base constructor and strip builder are designed to retread tyres up to 63-inch rim size, 4000mm outer diameter and 1200mm width. In both machines technologies have been applied which VMI is confident offer great advantages over other retreading systems – in quality as well as capacity – and thus costs. The systems are also suitable for the building of new OTR tyres.