Novel Splice Vulcanizing Presses with Optimized Heating and Pressure Characteristics

The use of belt conveyors for bulk good transportation and especially for the transportation of extracted raw materials becomes increasingly important. Today’s needs and trends indicate longer transportation distances, which are associated with the necessity for enhanced belt strength. Popular example of high-strength conveyors is the belt conveyor arrangement in the mine Los Pelambres in Chile. Two belts of nominal strength according to ST 7800 and one according to ST 4000 are in operation. A further example is the coal mine Prosper-Haniel in Germany where a belt of a nominal strength according to ST 7500 is employed.

Transporting conveyor belts, in the form of reels, from the belt manufacturing facilities to the excavation site is a challenging task limited by the reel size and weight. Most of the times, it involves breaking up the foreseen total belt length into segments to subsequently be manufactured, reeled, transported and eventually assembled on the spot. A high-strength 3.7 km long conveyor belt would typically need 18 splices. Employing high-strength conveyor belts corresponds with breaking up the total belt length into even more segments than the transportation of a conventional strength belt of the same total length would require, due to increased size and weight of the embedded cable infrastructure.

The duration of the splicing process depends on the belt width, the nominal belt strength and the associated length of the belt splice. The splice vulcanization process (heating up to vulcanization temperature, remaining at the desired temperature and cooling) for a belt of nominal strength according to ST 7500 requires around 4 hours, without taking into account the rather time-consuming preparation process of laying the cables and the assembly or disassembly of the vulcanization press. This illustrates why splicing is regarded as one of the most important financial and temporal factors concerning the installation and maintenance of belt conveyors.

Within the framework of a research project between NILOS GmbH and Co. KG and the Institute of Transport and Automation Technology (ITA) of the Gottfried Wilhelm Leibniz University Hannover new mechanisms and methods are demonstrated for the optimization of belt splice manufacturing process. Main objective of this cooperative project is to develop innovative and novel concepts for splice vulcanization presses that optimize the splice processing time. For optimization of temperature distribution, mechanisms of microwave and induction heating have been examined. Due to easier implementation and practicality, the mechanism of induction heating was focused for laboratory tests. The development of systems applying homogeneous pressure will be an objective in future work.