US4738197A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Cooling of a paper web in a supercalender
Assignee: Valmet Technologies Oy
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Filing: 1985-11-15
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Granted: 1988-04-19
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Expires: 2005-11-15
Abstract
Abstract The invention relates to a method for accomplishing smoothness and glaze to paper or board webs in a calender by leading a web through hot nips which are formed between cooperating rolls of different hardnesses and having adjustable temperatures, and where a gradient calendering of the web based on the temperature difference between the web and the rolls is brought about. In order to increase the efficiency of the gradient calendering and in order to achieve a suitable temperature difference between the web and the heated rolls, the temperature of the web is arranged to be adjustable before the web enters the hot nip.
Inventors
- 👤 Hannu Malkia
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 14:53
CPC Classifications
D; D21; D21G; D21G1/00; D21G1/0073; D21G1/0093
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
115 words
A method for imparting smoothness and glaze to an uncoated web of paper or board in a calender by means of leading a web through hot nips which are formed between cooperating heated rolls of different hardnesses and having adjustable temperatures, in which calender a gradient calendering of the web is brought about, based on a temperature difference between the web and the heated rolls, so that, in order to increase the efficiency of the gradient calendering and in order to achieve a suitable temperature difference between the web and the heated rolls, the web is cooled before it enters the hot nip, the cooling being substantially uniform in the transverse direction of the web.
Claim 2
Independent Claim
115 words
A method for imparting smoothness and glaze to an uncoated web of paper or board in a calender by means of leading a web through hot nips which are formed between cooperating heated rolls of different hardnesses and having adjustable temperatures, in which calender a gradient calendering of the web is brought about, based on a temperature difference between the web and the heated rolls, so that, in order to increase the efficiency of the gradient calendering and in order to achieve a suitable temperature difference between the web and the heated rolls, the web is cooled before it enters the hot nip, the cooling being substantially uniform in the transverse direction of the web.
Claim 3
Dependent Claim
31 words
A method according to claim 1, where the web is cooled so, that its temperature when entering the nip is not higher than 70° C., favourably not higher than 50° C.
Claim 4
Dependent Claim
29 words
A method according to claim 1, where the temperature difference in the nip between the web and the rolls is at least 30° C., favourably at least 40° C.
Claim 5
Dependent Claim
64 words
A calender for treating a heated web which is delivered to the calender, comprising (a) means for cooling the heated web substantially uniformly in the transverse direction of the web, (b) at least two rolls which define a nip therebetween for receiving the cooled web, the rolls being of different respective hardnesses, and (c) means for heating each roll to a selectively adjustable temperature.
Claim 6
Dependent Claim
64 words
A calender for treating a heated web which is delivered to the calender, comprising (a) means for cooling the heated web substantially uniformly in the transverse direction of the web, (b) at least two rolls which define a nip therebetween for receiving the cooled web, the rolls being of different respective hardnesses, and (c) means for heating each roll to a selectively adjustable temperature.
Claim 7
Dependent Claim
69 words
A calender according to claim 4, in which the cooling means consist of take-out or guide rolls belonging to the calender or of separate cooling rolls or cylinders, in which rolls or cylinders the cooling is carried out either by means of an internal cooling device based on water circulation or some corresponding system, or by means of external cooling based on gas blasting, liquid jet or the like.
Claim 8
Dependent Claim
27 words
A calender according to claim 4, in which the cooling of the web is carried out by directing a cold gas or liquid jet to the web.
Claim 9
Dependent Claim
35 words
A calender according to claim 6, in which the cooling means also can be used for gradient calandering based on a difference between the moisture contents of separate layers of the thickness of a web.
Claim 10
Independent Claim
70 words
A method of calendering an uncoated web of paper or board, comprising cooling the web substantially uniformly in the transverse direction of the web without exposing it to substantial pressure, feeding the cooled web through a nip defined by external surfaces of cooperating heating rolls, and maintaining the external surface of each heating roll at a temperature that is higher than the temperature of the web prior to being cooled.
Claim 11
Independent Claim
70 words
A method of calendering an uncoated web of paper or board, comprising cooling the web substantially uniformly in the transverse direction of the web without exposing it to substantial pressure, feeding the cooled web through a nip defined by external surfaces of cooperating heating rolls, and maintaining the external surface of each heating roll at a temperature that is higher than the temperature of the web prior to being cooled.
Claim 12
Dependent Claim
20 words
A method according to claim 8, wherein the web is cooled by directing a stream of liquid against the web.
Claim 13
Dependent Claim
20 words
A method according to claim 8, wherein the web is cooled by directing a stream of gas against the web.
Claim 14
Dependent Claim
54 words
A method according to claim 8, wherein the web is cooled by bringing one side of the web into contact with a member which is at a temperature that is lower than the temperature of the web prior to being cooled, the side of the web opposite said member being exposed to atmospheric pressure.
Claim 15
Dependent Claim
18 words
A method according to claim 8, comprising cooling the web to a temperature not higher than 70° C.
Claim 16
Dependent Claim
30 words
A method according to claim 8, comprising cooling the web to a temperature that is at least 30° C. below the temperature of the external surfaces of the cooperating rolls.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-04-19 | 1991-10-19 | 1992-04-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-04-19 | 1995-10-19 | 1996-04-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-04-19 | 1999-10-19 | 2000-04-19 | $7700.00 | Window Closed / Lapsed |