Web surface treating apparatus

Abstract

A five roll calendar apparatus includes five rolls mounted in a common horizontal plane, including three heated rolls with first and second covered rolls. Each heated roll includes an inner rigid core having an outer finished surface. A plurality of grooves are formed by machining the face of the core and a thin sleeve is shrunk fit onto the core to seal the grooves and establish heat transfer passageways. The size of the passageways, the separating lands and the shell thickness are such that the temperature at the surface of the roll is essentially constant over the portions of the cavity and the adjacent core body. The thin outer wall establishes a short time response for correcting the temperature of the web. The center roll is rotatably fixed and the other rolls are individually loaded toward the fixed roll for controlling of nip pressure. The covered rolls are mounted in suitable slide supports. The end rolls are mounted to a torque shaft which provides a high degree of squareness to the roll loading. A roll squeezes surface air from the web. Grooved guide rolls maintain proper web flatness. Heat sensing units are located to monitor web surface temperature and each is connected in a closed loop control for a heated roll.