Annealing is an important process in the coating of sheet steel in order to achieve better processability and reduced hardness of the metal. In the continuous annealing process, the individual steel sheets are automatically welded together at their ends so that they form an endless strip. There is a buffer tower in the annealing section as an inlet and outlet storage tank. The towers ensure a steady flow of steel by continuously feeding an adjustable quantity of steel into the processing lines. At the heart of the buffer towers are four roller chains that raise and lower special platforms to feed and discharge the steel. These drive chains are subject to heavy loads and must be lubricated accordingly with oil or grease; these media must not be allowed to enter the annealing process. It is therefore important that the steel is fed in cleanly. This requires precise lubrication and is like walking a tightrope: if the lubrication is too high, the steel becomes contaminated, if it is too low, the chain becomes dry and fails prematurely.

In this case, the height of the tower made it difficult to access the chains for maintenance work and the steelworks operator carried out the maintenance work rather irregularly and reactively. As a result, the original chains buckled and failed due to inadequate lubrication - they had to be replaced.

Drive specialist Tsubaki recommended replacing the existing chains with their standard BS chains. The manufacturer has improved the technology of the "GT4 Winner" in several design generations so that it currently meets the requirements of most applications. This current eighth-generation version with the G8-RS roller chain offers a 20 percent longer service life compared to the previous generation. One of the features, for example, is a special chain lubrication that is applied in the final production step; it inhibits corrosion and increases the service life of the chain. The oil developed in-house leaves no sticky residue on the chain surface that could be transferred to the steel plates.

The G8-Super is a high-performance drive chain and was designed for applications in which heavy loads have to be transported at low speeds. Based on a new heat treatment process, the use of thicker material and an improved geometry, this chain offers more strength compared to the standard GT4 chain. This made the replacement chain ideal for the buffer tower. However, very long chain strands are installed here, which can cause problems in synchronous running due to different wear elongation; here too, Tsubaki was able to ensure the required tolerance in chain strands used in pairs or groups. pb