A COMPOSITION OF MATTER FOR COATING A PRESS ROLL

Abstract: A composition of matter is disclosed for coating a press roll (10A). The composition (18) defines a roll surface (16A) for contacting a web (WA) of paper extending past the press roll (10A). The press roll (10A) is a replacement for a natural granite press roll. The composition (18) includes an aluminosilicate and an alkaline-earth metal oxide.

Description: PATENT APPLICATION TITLE: A COMPOSITION OF MATTER FOR COATING A PRESS ROLL BACKGROUND OF THE INVENTION FIELD OF THE INVENTION The present invention relates to a composition of matter for coating a press roll. More particularly, the present invention relates to a composition for coating a press roll which is a replacement for a natural granite press roll. INFORMATION DISCLOSURE STATEMENT In the papermaking art, as the speed of rotation of typical natural granite press rolls increases, there is an ever-present danger of such press rolls fracturing and fragmenting. A typical prior art natural granite press roll may operate in the region of 3,500 feet per minute and such press roll may weigh in the region of 100 tons. It is evident that the fragmentation of such a roll can pose a serious operational hazard. In fact, several fatalities have resulted from the aforementioned break-up of natural granite press rolls. Consequently, particularly in Europe, the use of natural granite press rolls has been outlawed. Accordingly, the present invention provides a synthetic or substitute granite surface on a tubular metal shell in order to provide a press roll. Not only does the substitute granite roll of the present invention avoid the aforementioned potentially hazardous conditions associated with the prior art natural granite press rolls but also affords a considerable cost saving, particularly in view of the rapid depletion of natural sources of natural granite around the world. Therefore, it is a primary objective of the present invention to provide a composition of matter for coating a press roll which overcomes the aforementioned inadequacies of the prior art natural granite press rolls and provides a significant contribution to the art of pressing water from a formed web. Another object of the present invention is the provision of a composition of matter for coating a press roll, such composition including an aluminosilicate and an alkaline-earth metal oxide. Another object of the present invention is the provision of a press roll for a press section of a papermachine for pressing water from a web extending past the press roll, the press roll including a tubular metal shell defining a cylindrical outer surface and a roll cover sprayed onto the outer surface, the roll cover including an aluminosilicate and an alkaline-earth metal oxide. Another object of the present invention is the provision of a press roll in which the roll cover is either thermally or plasma sprayed onto the outer surface. Other objects and advantages of the present invention will be readily apparent to those skilled in the art by a consideration of the detailed description contained hereinafter taken in conjunction with the annexed drawings. SUMMARY OF THE INVENTION The present invention relates to a composition of matter for coating a press roll and a press roll for a press section of a papermachine. The composition defines a roll surface for contacting a web of paper which extends past the press roll. The press roll is a replacement for a natural granite press roll. The composition includes an aluminosilicate and an alkaline- earth metal oxide. The composition is plasma sprayed onto the roll such that the roll surface simulates a granite surface of a granite press roll. More particularly, the composition includes an aluminosilicate within the range 95 to 99.9 percent by weight and the alkaline-earth metal oxide is within the range .1 to 5 percent by weight. In a specific embodiment of the present invention, a press roll for a press section of a papermachine presses water from a web extending past the press roll. The press roll includes a tubular metal shell which defines a cylindrical outer surface. A roll cover is sprayed onto the outer surface. The roll cover includes an aluminosilicate and an alkaline-earth metal oxide. In one embodiment of the present invention, the roll cover is thermally sprayed onto the outer surface, and in another embodiment of the present invention, the roll cover is plasma sprayed onto the outer surface. Many modifications and variations of the present invention will be readily apparent to those skilled in the art by a consideration of the detailed description contained hereinafter taken in conjunction with the annexed drawings. However, such modifications and variations fall within the spirit and scope of the present invention as defined by the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a side-elevational view of a typical prior art natural granite press roll; Figure 2 is a side-elevational view, partially in section, of a press roll according to the present invention showing a roll cover as a composition of matter applied to the outer surface of a tubular metal shell. Similar reference characters refer to similar parts throughout the various views of the drawings. DETAILED DESCRIPTION OF THE DRAWINGS Figure 1 is a side-elevational view of a typical prior art natural granite press roll generally designated 10. The press roll 10 includes an axle 12 rotatably secured within journal bearings (not shown) . A sleeve 14 of natural granite is rigidly secured to the axle 12 such that the sleeve 14 rotates with the axle 12. The sleeve 14 defines an outer cylindrical surface 16 which comes into physical contact with the web W. Figure 2 is a side-elevational view, partially in section, showing a press roll 10A according to the present invention. A composition of matter, generally designated 18, coats the press roll shell 21. The composition defines a roll surface 16A for contacting a web WA of paper extending past the press roll 10A. The press roll 10A is a replacement for a natural granite press roll of the type shown in Figure 1. The composition includes an aluminosilicate and an alkaline-earth metal oxide. The composition 18 is plasma sprayed onto the roll shell 21 such that roll surface 16A simulates a granite surface of a granite press roll. The composition 18 includes aluminosilicate within the range 95 to 99.9 percent by weight and alkaline-earth metal oxide within the range .1 to 5 percent by weight. More particularly. Figure 2 shows the press roll 10A for a press section of a papermachine for pressing water from a web WA extending past the press roll 10A. The press roll 10A includes a tubular metal shell 21 which defines a cylindrical outer surface 22. A roll cover, generally designated 18, is sprayed onto the outer surface 22 of the shell 21. The roll cover 18 includes aluminosilicate and an alkaline-earth metal oxide. In one embodiment of the present invention, the roll cover is thermally sprayed onto the outer surface 22, and in another embodiment of the present invention, the roll cover 18 is plasma sprayed onto the outer surface 22. The present invention provides a relatively low cost synthetic granite press roll which overcomes the aforementioned hazards associated with the prior art natural granite press rolls. Additionally, the synthetic granite roll of the present invention overcomes the problem caused by the scarcity of relatively massive blocks of natural granite suitable for fabrication into natural granite press rolls.

Claims: What is Claimed is: 1. A composition of matter for coating a press roll (10A), the composition (18) defining a roll surface (16A) for contacting a web (WA) of paper extending past said press roll (10A), said press roll (10A) being a replacement for a natural granite press roll, said composition (18) comprising: an aluminosilicate; and an alkaline-earth metal oxide. 2. A composition as set forth in claim 1 wherein said composition (18) is plasma sprayed onto the roll (10A) such that the roll surface (16A) simulates a granite surface of a granite press roll. 3. A composition as set forth in claim 1 wherein said composition (18) includes said aluminosilicate within the range 95 to 99.9 percent by weight; and said alkaline-earth metal oxide within the range .1 to 5 percent by weight. 4. A press roll (10A) for a press section of a papermachine for pressing water from a web (WA) extending past said press roll (10A), said press roll (10A) comprising: a tubular metal shell (21) defining a cylindrical outer surface (22); a roll cover (18) sprayed onto said outer surface (22); said roll cover (18) including: an aluminosilicate; and an alkaline-earth metal oxide. 5. A press roll (10A) as set forth in claim 4 wherein said roll cover (18) is thermally sprayed onto said outer surface (22). 6. A press roll (10A) as set forth in claim 4 wherein said roll cover (18) is plasma sprayed onto said outer surface (22). AMENDED CLAIMS [received by the International Bureau on 22 December 1992 (22.12.92 ) ; original claims 1-3 deleted; original claim 4 amended; remaining claims unchanged (1 page) ] 4. A press roll (10A) for a press section of a papermachine for pressing water from a web (WA) extending past said press roll (10A), said press roll (10A) comprising: a tubular metal shell (21 ) defining a cylindrical outer surface (22); a roll cover (18) sprayed onto said outer surface (22); said roll cover (18) including: an aluminosilicate; and an alkaline-earth metal oxide wherein said alkaline-earth oxide is within the range .1 to 5 percent by weight with the remainder of the roll cover being said aluminosilicate. 5. A press roll (10A) as set forth in claim 4 wherein said roll cover (18) is thermally sprayed onto said outer surface (22). STATEMENT UNDER ARTICLE 19 The claims in the subject PCT application have been amended to conform with those claims pending in the corresponding U.S. patent application and are believed to define novel subject matter and inventive step over the art of record.

Inventors: MCCARTEN PAUL, MCCARTEN, PAUL
Applicants: BELOIT TECHNOLOGIES INC, BELOIT TECHNOLOGIES, INC.
Application year: 1992
Main classification: D21F3
IPC codes: C23C4, D21F3, G06F13