Reduced wear by converting the fastening units on the X-Roll® oil bearings in the temper rolling mill 3 at thyssenkrupp Rasselstein GmbH while simultaneously increasing safety at work.
Oil bearings in older installations are typically pulled on and off by turning a ring nut seated on the roll journal. Due to large dimensions und the resulting high frictional resistance, the ring nut is tightened by means of wire rope sling and shop crane. The reproducibility and the control of the pulling-on forces is difficult, the risk of accidents is high.
A conversion to a hydraulic fastening system – as it is standard with modern oil bearings – is obvious, but often fails when it comes to the available assembly space, the prohibition of changing the existing backup roll geometry or an insufficient budget.
New Bolt Mount fastening system
In response to this situation, SMS group has developed a new cost-effective mechanical fastening system. The principle of the new BM (Bolt Mount) fastening system is based on the fact that the required pulling-on and -off forces of several screws uniformly distributed over the circumference are fitted on in a torque-controlled, reproducible and safe manner. The existing backup roll geometry is maintained. Safeguarding of the axially positioned bearings on the roll journal takes place through positive locking and on a decoupled basis from the pulling-on force.
With the new BM fastening system we have increased safety at work in our roll workshop and thanks to a controlled pulling-on force, we hardly observe any wear on journal bushings.
The practicability has been tested and optimized for 18 months in the temper rolling mill 3 at thyssenkrupp Rasselstein in Andernach, Germany, when four BM fastening systems were employed during 100 pulling-on and -off operations and more than one million tons of tinplate produced. thyssenkrupp Rasselstein confirms the compliance with all requirements on the new BM fastening system. In addition to that, the assumption was confirmed that in the past the bearings had always been fastened too tightly and in a less gently manner to the material.