This paper introduces horizontal shaft of vertical mill is changed into statically indeterminate beam supported by three points used of virtual constraint in the reforming process of RE1 vertical mill transmission device of 500mm hot strip mill production line in Laiwu iron and steel general works,thus the strength,rigidity and transmission stability of this mill are increased.

According to the testing parameters of a 4200 vertical mill and by using the numerical calculation combined with theoretical analysis,this paper proposes a nonlinear vibration model with four degrees of freedom for the main transmission system of the vertical medium plate mill.

The article describes the function, composition and operational concept of edger mills.

The development of heavy plate mill and the common characteristics of the mill revamping were summarized, and the production technologies, such as control links of TMCP, appliction of edger mill and the processing of Steckel mill for plate were introduced.

The head and the tail of the slab formed instability parts due to haven\'t backward stress during the Edger mill rolling.