To extend the mill window height and retain the large stress relieving radii in the corners, the Metalock Engineering Group designed and built a separate milling machine that could be used while the sides of the mill were being machined.
Completion of a series of complex in-situ machining operations by the Metalock Engineering Group for SAPA HeatTransfer at Finspong in Sweden has meant that their 1500mm wide hot mill is now capable of rolling slabs that are 60% larger than previously. It can now cope with 10-tonne billets instead of the 6 tonnes the mill was designed for and, enable a significant increase in output. It is quicker to roll a 10-ton-slab than two of the smaller ones.
Project managers for the job were VAI Industries (UK) who selected the Metalock Engineering Group to undertake the in-situ machining work due to previous experience of working with them on several other projects.
The alternative of removing the housings for modification was unacceptable because of the time that it would take.
To permit these increases the mill had to be significantly upgraded to accept new equipment and in particular, the mill window height extended to accommodate the thicker slabs. Work was also needed to allow new screwsets to be installed.
The Metalock team, made up of engineers from Coventry and colleagues from Sweden, machined outside and inside faces on the mill windows for new equipment to be fitted. Having upgraded steel rolling mills all over the world Metalock used their specially designed in-situ machining bed equipped with a dual milling head. This allows both sides of the mill window to be machined simultaneously, substantially reducing the time taken on each housing.
External faces of the operator and drive side housings were machined and the wear plate height increased by 200mm on all four posts. In addition, 60mm deep pockets were milled on the inside faces of the housing to accommodate new components.
To extend the mill window height by 30mm and relieve large stress raising radiuses in the corners the Metalock Engineering Group designed and built a separate milling machine that could be used while the sides of the mill window were being milled. To increase the diameter and deepen the bores for the new screwdown equipment, Metalock used a purpose designed boring attachment and another for drilling and tapping new holes for the screwdowns.
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