Metal working – Burnishing – Of water laid fibrous article
Reexamination Certificate
1995-06-07
2001-06-12
Johnson, Brian L. (Department: 3618)
Metal working
Burnishing
Of water laid fibrous article
C451S296000, C451S532000
Reexamination Certificate
active
06243934
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method and apparatus for polishing paper. In particular, the method and apparatus utilize a polishing belt and cylinder in order to obtain the desirable properties that mechanical shear action imparts to paper. The polishing belt is made from a woven base layer with a matte affixed thereto. The matte includes a plurality of batting fibers which have abrasive means permanently mounted thereon for polishing a paper surface.
2. Description of the Background Art
To impart mechanical energy to a paper surface, a frictional device is left with only three variables; contact force, sliding distance and the coefficient of friction of the frictional material. This relationship can be expressed as E
m
=Nud where E
m
=Mechanical energy, N=Normal or contact force, u=coefficient of friction of the polishing surface and d=sliding distance.
The devices considered to be the prior art are at either end of the spectrum, with respect to contact force and distance. These prior art devices have relatively low coefficients of friction for the frictional surface in most cases.
One prior art example uses brush polishing devices which rely on low contact forces and large slip distances. Surface speed differentials typically approach 15,000 feet per minute (fpm). Brush polishers are limited to material operating speeds of 1,500 fpm by mechanical limitations of the rapidly spinning brushes and bristle performance.
Such brush polishers usually have a bristle diameter which is large enough to easily create visible brush marks. Also, the amount of polishing effectiveness of the brush bristles is limited because the bristles cannot be compressed against the sheet of paper. The tips of the bristles do the majority of the polishing work. These tips have a small number of microscopic edges per unit area of polishing material surface thereby limiting effectiveness. Also, the diameter/circumference of the cylinder on which the bristles are mounted is limited thereby limiting a width of the paper to be treated.
One prior art device disclosed in U.S. Pat. No. 4,089,738 to Kankaanpaa also describes stationary devices which drag hard surfaces against paper with higher contact forces compared to brush polishers. The slipping distances between differentials used in these relatively stationary devices are essentially directly related to web speed. Stationary frictional devices as described by Kankaanpaa generate tremendous heat and wear requiring the frictional surfaces to be made of steel or ceramic with relatively low coefficients of friction. The potential for scratching or the chance for developing a machine direction character on the paper is high because there is little opportunity to clean the device during operation, the polishing surface is very hard and the speed differentials are still relatively high (2,500 to 5,000 fpm). Also, this device is designed for polishing uncoated paper. The disadvantages with this approach and other burnishing processes with steel or ceramic include the inflexibility of the hard polishing surface which makes high contact force necessary to achieve the desired results. The high contact force results in high wear, high heat generation and a high probability of marketing/scratching of the product.
An invention described in U.S. Pat. No. 2,349,704 to Clark uses soft rollers with a polishing powder to develop a high coefficient of friction between the paper and the frictional device. This relatively high coefficient of friction device along with relatively high speed differentials results in micro-scratching with presumably low contact forces. Also, the polishing powder is not securely bonded to the soft rollers. Therefore, the polishing powder will contaminate the paper product. To avoid this drawback, the efficiency and operating speed of the device is limited, but contamination can still occur.
SUMMARY OF THE INVENTION
Accordingly, it is a primary object of the present invention to exploit the middle ground in imparting mechanical energy to paper via friction and to use a cost effective polishing material by modifying a product already economically and routinely produced in the paper industry.
It is another object of the present invention to provide a wear surface of the polishing material which can be extended to large distances resulting in a large quantity of material being available for wear.
It is yet another object of the present invention to provide a belt device which can develop sufficient belt tension to produce a polishing pressure of 1 to 30 psi.
It is a further object of the present invention to provide a belt which can wrap a cylindrical backing roll to give an extended contact/working length which increases the dwell time of the paper while it is being worked on by the belt.
Another object of the present invention is to provide extended working lengths which allow for the use of relatively small speed differentials between the paper and the belt.
It is yet another object of the present invention to provide extended working lengths of a belt device which allow for higher machine speeds compared to rotary brushes or roll polishing devices.
It is still another object of the present invention to provide a belt device having a very large percentage of its length available for cleaning, conditioning and static control when not working on the paper.
It is another object of the present invention to provide a frictional type paper polishing device which is able to efficiently dissipate heat produced during the polishing process.
Yet a further object of the present invention is to provide a fabric for the polishing belt which has small diameter fibers which will greatly reduce or eliminate visible markings on the polished paper.
Still another object of the present invention is to provide a belt which can be tensioned in such a way that contact pressure of 20 psi or more can be generated giving the belt the ability to do more work on the material than conventional brush polishers.
Another object of the present invention is to provide a polishing belt with a large number of microscopic edges per unit area of polishing surface in order to increase the effectiveness for polishing fabric.
Still another object of the present invention is to provide a polishing belt with abrasives which are securely bonded to the fiber to thereby reduce potential product contamination.
It is a further object of the present invention to provide a polishing belt which does not require high contact force which results in high wear, high heat generation and possible marking/scratching of the paper surface.
These and other objects of the present invention are fulfilled by a polishing belt which has a base layer woven to form a continuous belt. A matte is affixed on the base layer. This matte includes a plurality of batting fibers. Abrasive means are permanently mounted on the batting fibers. These abrasive means will polish the surface of the paper.
These and other objects of the present invention are also fulfilled by a method comprising the steps of feeding a length of paper at a first speed around a portion of a cylindrical roll. A polishing belt is then pressed against a length of the paper at a second speed. The paper will be between the polishing belt and the cylindrical roll. The first speed of the paper feed is different than the second speed of the polishing belt. The paper will be polished by the polishing belt. This paper moves relative to the polishing belt during the step of polishing. The polishing belt has a base layer and a matte affixed on the base layer. The matte includes the plurality of batting fibers which have abrasives permanently mounted thereon. The step of polishing includes abrading the surface of the paper with the abrasives on the batting fiber. These abrasives are maintained on the batting fiber to thereby avoid contamination of the paper with the abrasives.
Moreover, these and other objects are fulfilled by a method for polishing paper comprising the s
Appleton Coated, LLC
Birch & Stewart Kolasch & Birch, LLP
Johnson Brian L.
Luby Matthew
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