TPT July 2014

Technology News

Wear resistant chains for the steel industry

between pin and chain link plate forming a further contribution to a fatigue resistant connection respectively a successful chain execution. To ensure the homogeneity of two or multiple chain strands running parallel to each other, the individual chain strands may be matched and marked according to the length measurement results of each individual strand in addition to the wall thickness deviation measurement of each bush. A well-balanced concept under consideration of all chain and conveying equipment parameters contribute to operational safety and corresponding operational lifetime. KettenWulf Betriebs GmbH – Germany Fax: +49 2973 801 2296

INCREASING demands on the availability and wear resistance of chains in various applications of the steel industry require modern concepts in the design and realisation of the employed products. Corresponding solutions and products are being offered by KettenWulf Betriebs GmbH. The company’s product range of conveyor and drive chains covers applications from pig iron preparation, steel production and onward processing up to the transport of the finished products. Requirements on availability and wear resistance are the key points for KettenWulf’s concept of efficient products under consideration of the cost structure. Besides the fatigue strength, the wear resistance in the chain joint plays a major role in the life time cycle of a chain. The consideration of the geometry of the individual chain components – dimensioning of link plates, bushes, pins and rollers – as well as the adherence to bearing pressure limits between bushes and pins, bushes and rollers and to the bearing stress at the sidebar pitch holes are basic requirements. While the breaking load and the fatigue strength are mainly determined by the geometry and the strength values of the link plates and pins, the wear resistance of a chain is influenced by a combination of geometry, grade of materials, heat treatment and a final surface finishing of the individual chain joint components. The material selection is the crucial factor for a successful chain concept. Besides the classic carbon steel C15, a number of alloyed and high alloyed case hardened steels, heat treatable steels with different alloying additions or fine-grained steels may be considered depending on the profile of the existing technical requirement. An additional heat treatment is a further step towards a highly wear resistant surface. Depending on the material grades, heat treatments of the product such as quenching and tempering, case hardening or induction hardening are carried out in KettenWulf’s own heat treatment facility.

Email: service@kettenwulf.com Website: www.kettenwulf.com

Along with a ductile core structure, a highly wear-resistant surface with a hardness of HRC 56-62 with depths of 0.6-6mm is achieved at a core strength of up to 1,200N/mm². When used in the warm area the reduction of the surface hardness in dependence on the ambient temperature and the chain temperature needs to be considered. A change of the geometry of the individual components may compensate such reductions. The final finishing process of the surface and the manual initial lubrication of the chain joints produce an additional constant against premature wear. To ensure a homogeneous chain concept, the fatigue strength and the breaking load have to be considered besides the wear resistance. The selection of the material grade and the production of the pitch holes are of vital importance for the reliability of a chain. Besides a quality steel having a tensile strength of minimum 700N/mm² there is a wide selection of very efficient heat treatable and fine-grained steels that may be used, including an additional heat treatment of the basic material depending on the chain application. The evaluation of different shapes of pitch holes for reduction of stress concentration at respective surface qualities has led to a maximum bearing contact area of the press fitment

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J uly 2014