Correct mill stand geometry is essential for effective and accurate gauge control, strip/plate quality and maintenance of the mill and its associated parts, like bearings, chocks, hydraulic clamps, bending and balancing systems as well as gauge control systems.
Housing windows of new mills create a stable and accurate location for roll chocks. After many years of service, the condition and alignment of mill stands deteriorates due to various factors, such as wear, corrosion, erosion or even foundation adjustment. This leads to problems attributed to incorrect positioning of work and back-up rolls and excessive movement of the roll chocks within the mill stand.
On-site machining is the most technically effective and long-lasting solution to the problems highlighted above. By machining the surfaces of the housing we are able to create a flat, parallel surface which is consistent throughout the height of the window and between operator and drive side housings. The process also removes any surface corrosion, ensuring the new mounting faces are free from any defect. This process requires the use of tailor-made machining tools along with a team of highly skilled technicians and engineers that Danieli Service is able to deploy all around the world.
Following the technical analysis, Danieli Service carries out detailed engineering to determine exactly all the problems affecting the rolling stand and define the best possible solution regarding liner thickness, chock reconditioning and machining amount. Once the most suitable course of action is confirmed the reconditioning process can begin.
This process begins during the annual maintenance shutdown and in this phase, as during the entire manufacturing process, laser measurement technology plays a vital role, checking the correctness for each step of the operation.
Once all surfaces have been machined and the fixation holes have been reconditioned, new oversized DanLiner wear plates are installed. DanLiner wear plates are made from Danieli leading technology for flat bearings characterized by a double-layer concept, where the top part of the liner is extremely hard and wear-resisting (58-62 HRC) while the bottom part is soft and protects the housing from future damage – such as the damage that has been just removed with on-site machining process.
