Advance Systems, Inc.

Daniel J Hansen

Randall D Helms

An offset printing apparatus has a fluid-cooled nip roll which, in use, presses a hot, rapidly moving, endless printed and dried web into intimate contact with the first downstream chill roll while avoiding damage to the web, nip roll, or chill roll, and while avoiding ink picking by the web surface contacted by the nip roll. Employing the nip roll in the system also permits the use of a substantially shorter dryer and fewer chill rolls as compared to a conventional system operating at the same web speed. A coolant circuit for the nip roll preferably includes a warmup loop which temporarily circulates warm fluid through the nip roll when the system is first taken off-line, thereby preventing condensate formation or frost formation on the nip roll.

Apparatus for preventing ink resoftening on a printed web as the web

A nip roll presses a hot, rapidly moving, endless printed and dried paper web into intimate contact with the exterior surface of a first downstream chill roll so as to improve the cooling efficiency of the first downstream chill roll, permit the use of fewer chill rolls, and prevent condensate streaking. The nip roll is specially designed to press the web into intimate contact with the first downstream chill roll while avoiding damage to the web, nip roll, or chill roll, and while avoiding ink picking on the web surface contacted by the nip roll. The nip roll has an elastomeric outer peripheral surface and is internally cooled so as to maintain the outer peripheral surface at an equilibrium temperature below that at which ink softening and resultant picking could occur. By eliminating concerns of condensate streaking, the nip roll also permits dryer operation at relatively low temperatures, thereby substantially reducing operating costs.

Apparatus and method for preventing ink resoftening on a printed web as

An offset printing apparatus has a fluid-cooled nip roll which, in use, is placed in intimate contact with a hot, rapidly moving, endless printed and dried paper web so as to improve the cooling efficiency of the first downstream chill roll, permit the use of fewer chill rolls, and avoid condensate streaking. The apparatus takes the form of a nip roll specially designed to press the web into intimate contact with the first downstream chill roll while avoiding damage to the web, nip roll, or chill roll, and while avoiding ink picking by the web surface contacted by the nip roll. Employing the nip roll in the system also permits the use of a substantially shorter dryer and fewer chill rolls as compared to a conventional system operating at the same web speed. The coolant circuit for the nip roll includes a warmup loop which temporarily circulates warm fluid through the nip roll when the system is first taken off-line, thereby preventing condensate formation or frost formation on the nip roll. The warmup loop preferably includes a heat changer that uses waste heat from the coolant circuit to heat the warmup fluid. Two or more nip rolls can be cooled and heated by a single coolant circuit.

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Green Bay, WI, United States of America

Daniel J Hansen