Paper making and fiber liberation – Apparatus – Running or indefinite length product forming and/or treating...
Patent
1986-03-14
1990-03-13
Hastings, Karen M.
Paper making and fiber liberation
Apparatus
Running or indefinite length product forming and/or treating...
162DIG1, 428217, 4284233, D21F 302
Patent
active
049081039
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
Field of the Invention
This invention relates to a bearing blanket for an extended nip press. More particularly, this invention relates to a bearing blanket for an extended nip press in which the blanket, a felt and a formed web pass through an extended nip defined by a rotatable press roll and a cooperating hydraulically loaded shoe.
Information Disclosure Statement
Traditionally, a press section of a papermaking machine has included a pair of counter rotating press rolls defining therebetween a nip for the passage therethrough of a formed web disposed adjacent a felt or between a pair of felts. With such prior art press nips not only is the residence time of the web within the nip very short, but the pressure applied to the formed web is extremely high.
With the advent of the extended nip press, the residence time of the web within the nip is greatly increased and the pressure exerted on the moving web can be significantly reduced. Not only does the extended nip press produce a pressed web which is 5 to 10 percentage points dryer than the corresponding web produced on conventional presses, but such extended nip presses result in the individual fibers within the formed web being pressed closer together thereby resulting in an improved quality in the end product.
The extended nip press includes a bearing blanket, a felt and a formed web which pass through an extended nip defined by a rotatable press roll and a cooperating hydraulically loaded shoe. The hydraulically loaded shoe urges the blanket against the felt during passage through the extended nip such that water is squeezed from the felt and web thus imparting an improved dewatering action.
The pressed web produced by such an extended nip press results in a paper web having 20 percent less water per ton compared with a similar web produced on a conventional press section. Therefore, the energy expended in the dryer section of the papermaking machine is correspondingly reduced. Additionally, production is increased by 25 percent. Furthermore, because of the increased residence time of the formed web in the extended nip, more water is able to migrate from the formed web into the felt.
In practical terms, for every gallon (3.8 liters) of water removed from a moving web in a conventional press section an extra 0.95 liters of water are removed with the extended nip press.
However, in earlier non vented extended nip presses bearing blankets of non vented construction having a continuous looped configuration were utilized. In such solid type blankets, water exuding from the felt during passage of the felt and blanket through the extended nip was unable to flow sufficiently quickly from the extended nip in order to avoid being entrapped between the felt and adjacent blanket during the passage of the web through the extended nip. Water so entrapped not only increased the fluid pressure within the extended nip, but also tended to rewet the formed web.
In an attempt to overcome the aforementioned problem, grooved blankets have been proposed in which a plurality of parallel grooves are formed parallel to the machine direction of the blanket so that water exuding from the felt by the interaction of the felt and blanket is able to flow unimpeded through the multiplicity of grooved channels and thereby inhibit the detrimental buildup of water pressure within the extended nip.
These grooved blankets or blankets having a plurality of recesses for the reception therein of water flowing from the felt have proved only partially successful because although such grooved blankets operate very successfully initially, there exists a tendency for such grooves to be crushed after extended use of the blanket.
The present invention provides a bearing blanket including a woven base and a first and second laminate. The second laminate defines a plurality of parallel grooves and is of urethane having sufficient hardness to inhibit crushing of the grooves while the first laminate is of a lesser hardness for permitting flexing of the second laminate
REFERENCES:
patent: 3613258 (1971-10-01), Jamieson
patent: 4206258 (1980-06-01), Balcar
patent: 4283454 (1981-08-01), Buchanan
patent: 4353296 (1982-10-01), Beucker
patent: 4431045 (1984-02-01), Josefsson
patent: 4482430 (1984-11-01), Majaniemi
patent: 4503113 (1985-03-01), Smart
patent: 4552620 (1985-11-01), Adams
patent: 4559258 (1985-12-01), Kiuchi
patent: 4564551 (1986-01-01), Best
Cronin Dennis C.
Lange David V.
Archer David J.
Beloit Corporation
Campbell Raymond W.
Hastings Karen M.
Veneman Dirk J.
LandOfFree
Bearing blanket for an extended nip press having laminates of di does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Bearing blanket for an extended nip press having laminates of di, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Bearing blanket for an extended nip press having laminates of di will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-49550