Patent ID: 9463497
Filing Date: 2016-10-11
CPC Classification: B21B

Claim Text:
1. A rolling mill stand defining a rolling axis, comprising a fixed outer structure, a roller holder cartridge, three or more working rollers arranged in the roller holder cartridge, the roller holder cartridge being mobile between a working position inside the fixed outer structure, at said rolling axis, and a side extraction position outside the fixed outer structure, specifically for changing the working rollers, wherein at least one respective hydraulic capsule is provided for each working roller, the capsule being rigidly fixed to the fixed outer structure to regulate the radial position of the respective working roller, having a distancing stroke from the rolling axis sufficient to allow the side extraction of said roller holder cartridge, further comprising a hydraulic system with a pressure and an exhaust circuit and a position control system of the three or more working rollers and of the at least one hydraulic capsule, each capsule having a main chamber and an annular chamber, characterized in that the position control system of said at least one hydraulic capsule comprises at least one servo valve of the four-way type and having two or more stages, the servo valve having a pressure port and an exhaust port, wherein the hydraulic connection between the servo valve and the corresponding capsule is such that the pressure port and exhaust port are disposable in fluid communication with respective ones of the main chamber and the annular chamber to effectuate prescribed positional adjustment of a corresponding one of the working rollers in a radial direction relative to the rolling axis.