Bearings – Rotary bearing – Antifriction bearing
Reexamination Certificate
2001-06-28
2004-04-20
Bucci, David A. (Department: 3682)
Bearings
Rotary bearing
Antifriction bearing
C384S590000, C074S056000
Reexamination Certificate
active
06722787
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a thrust ring for use in bearing systems for bolts of a universal joint for use in cardan shafts and to a method for producing a thrust ring. It also relates to a bearing system for bearing a bolt of a universal joint in a bearing bore of an articulated yoke for use in cardan shafts. Finally, it relates to a cardan joint arrangement having a bearing system of this type.
Cardan joint arrangements, in particular the bearing systems for bearing bolts of a universal joint in articulated yokes for use in cardan shafts, are known in a wide variety of designs for a multiplicity of possible uses. To represent this prior art, reference is made to a publication Voith Forschung und Konstruktion [Voith Research and Design], Vol. 33 (1998), Article 10 “Entwicklung wälzgelagerter Gelenkwellen für die Hauptantriebe schwerer Walzgerüste” [Development of cardan shafts mounted on rolling bearings for the principal drives of heavy rolling stands], and to Voith-Druck G 1135, 11.91. These documents disclose designs of cardan joint arrangements for cardan shafts which comprise at least one universal joint which is mounted in at least one articulated yoke. The articulated yoke itself may be of single-part or two-part design. To attach the universal joint in the articulated yoke, a suitable bearing arrangement is provided for each individual bolt. The bearing arrangement comprises at least one radial bearing and an axial bearing. There are numerous possibilities for the arrangement of the axial bearing, although a suitable design of the individual elements of the bearing will emerge when account is taken of the deformation which occurs while the cardan shaft is operating. Article 10 from Voith Forschung und Konstruktion, Vol. 33, discloses a design with a radial/axial bearing in which the individual components of the bearing arrangement, the seals, the connection structure of the bearings and the flange connections which transmit the torque are carefully matched to one another with regard to stress distribution and deformation under load. In this design, the radial bearing comprises three rows of solid cylindrical rolls which are guided inside the inner ring. The radial bearing inner ring is supported, via a collar, on the bolt end sides. An outwardly facing collar at the other end of the ring forms the inner race of the axial bearing. In this design, the axial force is introduced via the bolt end side. In this arrangement, the materials of the individual elements are selected according to their different functions, i.e. high-strength heat-treated steel is selected for the drop-forged universal joint and rolled case-hardened steel is selected for the bearing sleeve. The problem of a bearing arrangement of this type is that the individual rolling bearings are exposed to high torque impacts and simultaneous transverse accelerations, in particular when used in rolling mill drives. The impact loads, with large and rapidly changing bending angles, cause elastic deformation of the articulated yokes both in the region of the flange and inside the yoke eye. The bore widens and generally adopts a non-circular shape.
However, the introduction of the peripheral force causes the most deformation at the universal joint. The direction of this force oscillates with the positive or negative value of the operating bending angle and also changes with each reversing operation. These operation-related and design-related influences result in alignment errors with an unfavorable introduction of loads into the bearing, namely a center offset of the yoke bore, a skew positioning of the bore, bending of the bolt and radial play in the rolling bearing and spring deflection of the rolling bearing. The result is an uneven radial pressure distribution in the bearing bore, resulting in the contact at the locations of contact of the rolling bodies of the radial bearing changing from linear to punctiform, and also leading to excessive edge stresses. The rolling bearing connection parts, universal joint and articulated yoke are therefore adapted to one another in terms of deformation travel. Since the axial bearings of heavy cardan joints are generally arranged in the region of the root of the bolt of the coupling, these influences which have been listed lead to tilting of the axial bearing races. In this context, the deformation of the bolt in the region of the root has the greatest influence, since this is where the curvature of the bending line related to the bending moment is greatest. This leads to high edge stresses in one segment of the axial bearing and to the rollers lifting off in the opposite segment, leading to a drastic reduction in the load-bearing capacity.
To allow a simple structural design of a radial/axial bearing unit of the cardan joint, therefore, the races of the bearing sleeve for both bearings have been centered and axially fixed over the lateral and end faces of the bolt. If the bolt then bends under a load, the bearing sleeve follows a tangent which touches the bending line of the end of the bolt. Therefore, plane parallelism is retained even when the universal joint is under load. A significant drawback of a design of this type, however, is that the design of the individual bearing element is relatively complicated and requires a large number of elements, in particular with regard to the design of the bearing cover. During the structural execution, and in particular designing, of the individual components, therefore, it is always necessary to take account of the deformation travel which may occur, so that it is impossible to provide a satisfactory design irrespective of knowledge of these influences.
In another solution for fitting the bearing arrangement known from EP 0 785 370 A1. In this arrangement, the inner ring of the radial bearing, in the fitted position, on the axially inner side, includes a collar which extends radially away from the axis of the bolt mounted in the articulated yoke. The term axial is understood as meaning a direction which runs substantially parallel to the axis of the bolt mounted in the articulated yoke, as seen from the joint axis. In this context, the term joint axis is understood as meaning the extended axis of the component connected to the articulated yoke. This axis extends through the intersection point, whether it is either direct or projected into a plane, of the bolt axes of the universal joint. The axes of the bolts, which are offset in each case by 90° with respect to one another, may lie in a common plane or may be offset with respect to one another in mutually parallel planes.
The collar of the inner ring of the radial bearing at least indirectly forms the axially outer running surface of the axial bearing. This means that the collar may on the one hand directly form the running surface for the rollers or the rolling elements of the axial bearing designed in some other way, or on the other hand it is also possible for the running surface of the axial bearing, i.e. the outer ring of the axial bearing, as seen in the fitted position on the bolt, to be supported on this collar. In the fitted position, the outer ring of the radial bearing has, in the axial direction, an inner collar which extends radially toward the axis of the bolt mounted in the articulated yoke. The collar of the outer ring of the radial bearing at least indirectly forms the axially inner running surface of the axial bearing. The outer ring also has a so-called axially outer collar, as seen in the fitted position, which is assigned a stop in the yoke eye. Furthermore, the inner ring is assigned an axially outer collar, as seen in the fitted position, which is directed toward the axis of the bolt mounted in the articulated yoke and forms an axial stop for seating the inner ring in the end-side region of the bolt. This outer collar can be connected in a positive and/or nonpositive manner to the bolt mounted in the articulated yoke. This collar may be designed in such a manner that it forms a structural unit with the inner rin
Grawenhof Peter
Lindenthal Hans
Rösle Hans
Bucci David A.
Hansen Colby
Ostrolenk Faber Gerb & Soffen, LLP
Voith Turbo GmbH & Co. KG
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