Wide nip press with fluctuating blanket of extended wear area and how to extend the life of the fluctuating blanket

摘要

PURPOSE: An instrument is provided to increase the life span of a blanket in a closed press accepting a concave shoe and a backing roll. CONSTITUTION: An Extended Nip-type press (20) has a blanket (30) which passes over a shoe (22) which is urged against a backing roll (24) to form a press nip (56).A hydraulic system (70) and controller (94) provides for automatic continuous oscillation of the blanket (30) in the cross machine direction. The oscillation results in a region of high fatigue (58, 59) continuously moving over the blanket (30) surface so that the amount of time any particular region sees wear is minimized. Positioning of the heads (38, 42) to which the blanket (30) ends are mounted is controlled by hydraulic pistons (60, 62) mounted between a support beam (26) and the heads (38, 42). A controller (94)operates a valve (74) to reverse the direction of motion of the blanket (30) when sensors (92, 98) indicate one end of the blanket (30) has reached a stop (64, 80). A throttle valve (86) controls the rate at which hydraulic fluid is supplied to the cylinders (60, 62) which urge the head (38, 42) away from the shoe (22).