US4256034A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Paper calender and its operation
Assignee: Individual
•
Filing: 1979-08-17
•
Granted: 1981-03-17
•
Expires: 1999-08-17
Abstract
Abstract A paper calender using a polyurethane coated calendering cylinder is operated with the coating maintained at an unusually low temperature found to prevent damage to the coating when calendering at high speeds and pressures.
Inventors
- 👤 Eduard Kusters
- 👤 Werner Hartmann
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 19:31
CPC Classifications
D; D21; D21G; D21G1/00; D21G1/02; D21G1/0253; D21G1/0266; D21G1/0233; D21G1/0286; F; F16; F16C; F16C13/00
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
96 words
A paper calender comprising at least two substantially matching rotative cylinders for calendering a traveling paper web passed between them, one of the cylinders having a polyurethane coating, means for continuously rotating the cylinders so as to cause the web to travel with a velocity V, means for pressing the cylinders together so as to cause them to have a line pressure P on the web, and means for maintaining the coating at a temperature T during continuous calendering of the web, T being less than a temperature limit T G which equals 23-v/100-2(P/100) 2 .
Claim 2
Dependent Claim
96 words
A paper calender comprising at least two substantially matching rotative cylinders for calendering a traveling paper web passed between them, one of the cylinders having a polyurethane coating, means for continuously rotating the cylinders so as to cause the web to travel with a velocity V, means for pressing the cylinders together so as to cause them to have a line pressure P on the web, and means for maintaining the coating at a temperature T during continuous calendering of the web, T being less than a temperature limit T G which equals 23-v/100-2(P/100) 2 .
Claim 3
Dependent Claim
20 words
The calender of claim 1 in which the temperature T is not more than 2° C. below T G .
Claim 4
Dependent Claim
30 words
The calender of claim 1 in which said coating firmly connects with said cylinder and the coating has a wall thickness of from about 4 mm to about 6 mm.
Claim 5
Dependent Claim
59 words
The calender of claim 3 in which the coated cylinder is a hollow metal cylinder and contains a drum having a periphery closely spaced from the inside of the metal cylinder to form an annular space of small wall thickness, and means are provided for passing a coolant having a temperature less than -20° C. through the annular space.
Claim 6
Dependent Claim
21 words
The calender of claim 4 in which said coating has a hardness in the range of 60 to 75 Shore D.
Claim 7
Dependent Claim
96 words
Method for operating a paper calender having at least two rotating cylinders calendering a paper web traveling between them, one of the cylinders having a polyurethane coating with a hardness in the range of 60 to 75 Shore D, the method comprising rotating the cylinders so as to cause the web to travel with a velocity V while pressing the cylinders together to produce a line pressure P on the web, and cooling the coating heavily so its temperature T during the calendering is less than a temperature limit T G which equals 23-v/100-2(P/100) 2 .
Claim 8
Dependent Claim
96 words
Method for operating a paper calender having at least two rotating cylinders calendering a paper web traveling between them, one of the cylinders having a polyurethane coating with a hardness in the range of 60 to 75 Shore D, the method comprising rotating the cylinders so as to cause the web to travel with a velocity V while pressing the cylinders together to produce a line pressure P on the web, and cooling the coating heavily so its temperature T during the calendering is less than a temperature limit T G which equals 23-v/100-2(P/100) 2 .
Claim 9
Dependent Claim
45 words
The method of claim 6 in which the coated cylinder is a hollow metal cylinder coated with polyurethane, and said cooling is effected by flowing a liquid coolant having a temperature of less than -20° C. in contact with the inside of the hollow cylinder.
Claim 10
Dependent Claim
20 words
The method of claim 6 in which said web is cooled to the temperature T before contact with the cylinders.
Claim 11
Dependent Claim
20 words
The method of claim 6 in which V is greater than 350 m/min and P is greater than 80 kg/cm.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-03-16 | 1984-09-15 | 1985-03-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-03-16 | 1988-09-15 | 1989-03-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-03-16 | 1992-09-15 | 1993-03-17 | $7700.00 | Window Closed / Lapsed |