Rapid roll-separation procedure for calender - uses internal hydraulic devices to provide gentle retardation of fast-moving roll

摘要

The bottom roll of a calender machine is supported by a hydraulic jack whereby it can be rapidly lowered to separate the rolls in the stack by releasing the fluid pressure(described in appl. P28 45 055.7-27). The bottom roll is lowered a distance equal to the sum of the required sepns. of the individual rolls, the movement being continued for a braking distance amounting to at least 50% of the sepn. distance. Where the bottom roll comprises a cylindrical shell hydraulically supported on a fixed shaft by a series of hydraulic cylinders, whereof the piston stroke considerably exceeds the separation distance, the braking phase is effected by use of the internal hydraulics, controlled by an adjustable throttle in the release conduit. Despite a high-speed separation movement, this procedure allows the retardation of the bottom roll to be kept to a low value which avoids damaging shocks or deformation. It enables a more compact support jack tobe used having a shorter overall stoke.