When it comes to a lack of service life, excessive wear and tear and unreliability of drive chains, it is advisable to think outside the box and ask an alternative supplier. In the present case, a Dutch steel mill was able to increase the productivity of its heat treatment in the long term. How? Because Tsubkaki has replaced his failure-prone lifting chains with high-tech chains with a service life of up to 15 years.

In the coating of steel sheet annealing is an important process 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 to form an endless strip. In the annealing section there is a buffer tower each as inlet and outlet storage. The towers ensure the steady flow of steel by continuously feeding an adjustable amount of steel into the processing lines. The heart of the buffer towers is formed by four roller chains, which lift or lower special platforms for the supply and removal of steel.

Precise lubrication required

The drive chains are heavily stressed and must be lubricated with oil or grease accordingly. Of course, these media should not enter the annealing process. Therefore, it is important that the steel is fed cleanly. This requires precise lubrication and resembles a tightrope walk: If the lubrication is too high, the steel is dirty, if it is too low, the chain is dry and precipitates prematurely. 

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In the present application, it was made more difficult by the fact that the height of the tower made access to the maintenance work on the chains more difficult and that the steelworks operator carried out the maintenance work rather irregularly and reactively. This caused the original chains to buckle and fail due to lack of lubrication. The inspection of the broken chains showed that the wear was unevenly distributed, which overloaded other chain strands. So the steelwork turned to Tsubaki for help. The drive specialist has a range of innovative chain technologies in its portfolio, including lubricant-free and corrosion-resistant chains and chains for use in such demanding environments as the steel industry.

Specialists on site

After a visit to the steelworks, the drive specialists recommended replacing the existing chains with some of their standard BS chains. The technology of the "GT4 Winner" has been steadily improved in several design generations so that today it meets the requirements of most applications. This latest version of the eighth generation of the "G8 RS Roller Chain" offers 20 percent longer tool life compared to the previous generation. One of the features is, for example, a special chain lubrication, which is applied in the last production step. This inhibits corrosion and increases the service life of the chain. The in-house developed oil leaves no sticky residue on the chain surface that could be transferred to the steel sheets.

The G8 Super is a high-performance drive chain designed for applications where large loads need to be transported at low speeds. Based on a new heat treatment process, the use of thicker material and an innovative geometry, this chain offers greater strength compared to the GT4 standard chain. This made the replacement chain ideal for the buffer tower.

Ensure synchronous running

There was, however, another problem that bothered the steel producer: very long chain strands were built into the buffer tower, which caused massive problems in synchronous operation due to the different wear elongation. Here, too, the experienced drive specialist was able to help: due to similar problems in the past, the drive specialist added an optional production step in the manufacturing process, which ensures the required tolerance in chain strands used in pairs or in groups. With its unique "Match & Tag" service, the company guarantees a maximum chain length difference of 0,5 mm - regardless of the total length of the chain strands.

Finally, the sprockets were replaced, which are also made of high quality. To shorten the assembly time, the chains were delivered extra long. This has facilitated the installation in the high, difficult to access tower. The annually agreed inspection of the chains completes the customer-friendly service of TSUBKAI. Since the replacement of the drive elements, the buffer tower has been running continuously and very reliably.