The present invention relates to a slide bearing system surrounding a shaft in a roll for a paper/board machine or a finishing machine, comprising a body section which is formed with a bearing housing, said bearing housing being provided with hydrostatic bearing elements disposed around the shaft and fitted with slide elements, having a sliding surface directed towards the shaft, a bushing between the slide elements and the shaft, which is mounted on the shaft for rotation therewith, said slide elements being adapted to position themselves around the bushing with the sliding surfaces against the external surface of the bushing directed away from the shaft for supporting said shaft, and hence the roll, rotatably relative to the body section, and end caps, along with packing elements therefor, mounted on the axial ends of the bearing housing for sealing the bearing housing. The present invention relates further to a method for slide bearing a roll in a paper/board machine or a finishing machine, by means of an extra-roll slide bearing system.
This type of external slide bearing system or assembly can be used in connection with a variety of rolls, such as thermol rolls, center rolls, sizer rolls, felt rolls, etc. FI Patent application 970624 discloses an extra-roll slide bearing arrangement, wherein the slide elements of hydrostatic bearing elements mounted around a shaft are adapted to position themselves around a neck of the roll shaft for supporting the shaft, and hence the roll, rotatably relative to a bearing block. This type of prior art arrangement is depicted schematically in FIG. 1. The prior art solution shown in FIG. 1 comprises bearing elements, which are mounted on a bearing block 5 and capable of positioning themselves freely around a shaft 2 in a nip roll 1. Said nip is established together with a counter roll 1A. Reference numeral 3A represents a main load-carrying bearing and reference numeral 3 represents an abutment bearing. Reference numeral 3B indicates side bearings. Reference numerals 4A, 4 and 4B represent slide elements for bearing elements, respectively. As a result of the conicity of the shaft 2, the bearing elements are positioned to be slightly inclined relative to the rotation axis of the shaft 2, which has required certain special arrangements regarding the bearing block 5. The present Applicant""s earlier Finnish patent 104343 discloses a solution, in which a bushing is fitted between a slide element 4 and a shaft 2, having an external surface substantially cylindrical in cross-section. By virtue of this, the bearing elements can be disposed around the shaft 2 perpendicularly relative to its rotation axis.
The assembly and installation of such prior art slide bearings is demanding and involves a multitude of components in the process of fitting a roll with bearings. In addition, these prior art slide bearing systems must be assembled and tested with a roll or a separate test bushing. Moreover, the replacement of such a bearing assembly is a tedious process, and typically the entire roll is replaced by another roll outfitted with a standby bearing assembly. Furthermore, in solutions, wherein sliding surfaces are in a direct contact with a roll shaft, a sliding surface damage means that the roll will be damaged as well.
Consequently, it is one essential object of the present invention to provide an improved extra-roll slide bearing system, whereby the above drawbacks can be eliminated.
In order to achieve this object, a slide bearing system of the invention is characterized in that the slide bearing system is assembled for a single package, which is mountable on a shaft and dismountable from a shaft as a single package. A method according to a first aspect of the invention for slide bearing a roll in a paper/board machine or a finishing machine by means of an extra-roll slide bearing system is characterized in that the slide bearing system is assembled for a single package directly on a shaft. On the other hand, a method according to a second aspect of the invention is characterized in that the slide bearing system is assembled for a single package and mounted as a single package on a shaft.
One of the benefits offered by the present invention is that the entire slide bearing system is assembled for a single package, which is readily and quickly mountable on a shaft and dismountable from a shaft and which includes fewer components than the currently available bearing system. In addition, the assembly and testing of a bearing system can be implemented without a roll body and the roll can be replaced without a standby or substitute bearing system. Furthermore, the bushing included in the bearing system can be used as a fitting sleeve for old roll bodies. Still another advantage gained by the invention is an improved repairability in the events of bearing damage.