Method for controlling a two continuous strands rolling plant

A method for controlling a two continuous strands production plant, said two continuous strands being obtained by dividing a single continuous metal billet into two parts along a central longitudinal axis thereof, said production plant being provided with:

• one or more first rolling units for reducing the single billet to a substantially rectangular section,
• a rest bar having an inlet guide mounted thereon,
• a moulder unit for starting a deformation of the single billet so as to produce a rolled section consisting of two equally shaped parts joined along said central longitudinal axis,
• the rest bar being configured to regulate a transversal position of the inlet guide with respect to the moulder unit,
• one or more second rolling units for deforming the rolled section until achieving an almost complete separation of the two equally shaped parts of the rolled section,
• a cutting box for completing the longitudinal separation of the two equally shaped parts of the rolled section and producing two separate strands of the rolled section,
• one or more third rolling units for rolling said two strands, along respective rolling lines, comprising a last rolling unit of said plant consisting of a finishing block comprising two separate rolling sub-units which are regulated independently from each other, and positioned downstream of said first and second rolling units,
• a control system that calculates mass flow of each of said two strands based on measurements from a pair of speed sensors, said pair of speed sensors adapted to detect speed of the two strands for calculating the mass flow of the two strands, and arranged downstream of the cutting box, the pair of speed sensors including a first speed sensor arranged to detect speed of a first of the two strands and a second speed sensor arranged to detect speed of a second of the two strands,
• a cutting shear arranged downstream of said pair of speed sensors and of the last rolling unit, wherein said control method comprising:
• a step of measuring said speed of the two strands by means of the pair of speed sensors,
• step of calculating the mass flow of each of said two strands starting from said speed of the two strands and of calculating the difference of mass flow between said two strands,
• a feedback step on at least one component of said production plant which varies the mass flow along said lines so as to decrease the difference in length between the two strands as a function of said difference of mass flow between said two strands.