Calender for treating both sides of a paper web
AssigneeVoith Sulzer Finishing GmbH
InventorsFranz Kayser, Rolf van Haag, Ulrich Rothfuss
Life of this patent
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Abstract
A calender for the two-sided treatment of a paper web has two similar stacks each of which has at least two soft rollers and two hard rollers. Working nips are formed between each hard and soft roller. The calender has at least one working nip wherein the dwell time (t) is at least 0.1 ms, the surface temperature (T) is at least 100.degree.C., and the load (P) on the stack creates an average compressive stress in the working nip of more than 42 N/mm.sup.2. This provides a calender that is smaller and less expensive to manufacture and operate than super-calenders of the prior art but that also affords excellent finishing results.
Claims15
A calender for treating both sides of a paper web, comprising:
- two roller stacks, each of which is loaded on one end by a load, each roller stack comprising:
- at least two hard rollers having a substantially smooth outer surface, said at least two hard rollers each including means for heating a surface of said at least two hard rollers to a temperature of at least 100.degree. C.;
- and
- at least two soft rollers, wherein each of said at least two soft rollers is disposed adjacent to at least one of said at least two hard rollers to form a working nip therebetween, wherein at least one working nip has a predetermined width so that a dwell time of said paper web passing through said at least one working nip is at least 0.1 ms, said roller stack being loaded to produce an average compressive stress in said at least one working nip of at least 42 N/mm.sup.2.
Dependencies are inferred from the claim text.