Abstract:
A bearing arrangement comprises a sleeve having a cylindrical portion and a hemi-cylindrical portion; and a clamp having first and second halves, wherein the first half engages a surface of a shaft disposed through the sleeve, and wherein the second half has a hemi-annular recess for receiving the hemi-cylindrical portion of the sleeve.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a bearing arrangement and more specifically to a locking mechanism for securing a shaft in a bearing.  
           [0003]    2. Description of the Prior Art  
           [0004]    Conventional techniques for locking flanged, pillow-block, cartridge, and the like type of bearings to a shaft include, but are not limited to dual setscrew attachments (typically 2 screws at 65 degrees); tapered sleeves; and centering collars.  
           [0005]    In the case of roller element type bearings such as spherical bearings, special care must be taken to ensure the internal clearances of the bearing are not compromised (diminished to such a degree the bearing will not process effectively at load and speed). Presently, the two most common methods of securing this type of bearing to a shaft are the dual setscrews and tapered sleeves.  
           [0006]    The dual setscrew type clamping arrangement is the simplest method of securing a spherical bearing to a shaft. An example of this type of arrangement is shown in FIGS. 1A, 1B and  2 . This arrangement has two setscrews  10  threaded into a locking collar  11 . The setscrews  10  extend through clearance holes  12  formed in the bearing internal sleeve  14 , and bear on the shaft surface.  
           [0007]    This mechanism does not impact the internal clearance of the bearing  14 , but suffers from a number of drawbacks. Flats must be provided on the shafts and the two screws  10  must always be carefully torqued to specified levels to ensure that the appropriate gripping action is developed. Further, the screws must be replaced with new ones each time the collar is released because the tip of each setscrew is deformed by its initial use and will not produce the desired engagement if reused. In the event that the correct types of setscrews are not used, i.e., cup tipped setscrews, during the replacement, then the necessary relative rotation preventing grip will not be produced. If these requirements are not met, the locking action of the collar may be lost. This loss, of course, leads to slippage and undesirable detrimental effects.  
           [0008]    Another drawback of this type of locking mechanism is the shaft becomes eccentric to the bearing by virtue of pulling the clearance between the sleeve and the shaft in one direction. Furthermore, the integrity of the connection depends on the setscrews maintaining their preload under various process conditions including vibrations, cyclic loading, etc.  
           [0009]    Another technique of securing a spherical bearing is through a pair of tapered sleeves. With this arrangement, the inside diameter of the inner sleeve, typically split axially, is secured to the OD (outer diameter) of the shaft, while the OD of the outer sleeve is simultaneously secured to the ID (inner diameter) of the bearing race. By forcing the inner and outer sleeves toward one another along the shaft, the inner race of the bearing is expanded. This induces the drawback that the internal clearance between the rollers and the race elements tend to be diminished. Inasmuch as these type bearings have specific dimensional tolerances it is imperative to ensure that the degree of tightening is carefully controlled so that it provides the required connection but does not induce distortion that inhibits proper functioning of the bearing.  
           [0010]    [0010]FIG. 3 shows a variant of this tapered sleeve technique. This arrangement differs in that the inner race  22  of the bearing  20  is tapered and is arranged to cooperate with the split tapered sleeve which is inserted thereinto.  
           [0011]    The centering collar arrangement (not illustrated), while being less common than the above mentioned dual setscrew and tapered sleeve arrangements, is a known arrangement for attachment of radial bearings. This arrangement centers the bearing onto the shaft, and provides a positive method of clamping. Unfortunately, this arrangement is not recommended for spherical bearings due to possible distortion of the inner race and its effects on the internal clearances, and for lack of grip due to cantilevered flexed fingers and their inherent lack of surface area contact with the shaft.  
         SUMMARY OF THE INVENTION  
         [0012]    A first aspect of the invention resides in a bearing arrangement comprising: a sleeve having a cylindrical portion and a hemi-cylindrical portion; and a clamp having first and second halves, wherein the first half engages a surface of a shaft disposed through the sleeve, and wherein the second half has a hemi-annular recess for receiving the hemi-cylindrical portion of the sleeve.  
           [0013]    A second aspect of the invention resides in a bearing arrangement comprising: an inner race; an outer race; rolling elements interposed between the inner race and outer race; a sleeve integral with the inner race for rotation therewith, the sleeve having a hemi-cylindrical projection axially extending from one end thereof; and a clamp having a first section having a hemi-annular recess for receiving the hemi-cylindrical projection and a second section having an essentially hemi-cylindrical surface adapted for engagement with a shaft which is disposed through the sleeve.  
           [0014]    A third aspect of the invention resides in sleeve for a roller element bearing, comprising: a hemi-cylindrical projection axially extending from one end of the sleeve, the hemi-cylindrical projection being adapted to cooperate with a clamp which has a first part adapted to engage a peripheral surface portion of a shaft which is disposed through the sleeve, and a second part which is adapted to engage a peripheral surface of the hemi-cylindrical projection.  
           [0015]    A fourth aspect of the invention resides in a clamp for a roller element bearing having a sleeve having a hemi-cylindrical projection at one end, the clamp having a first portion adapted to engage a peripheral surface portion of a shaft which is disposed through the sleeve, and a second portion adapted to engage an outer peripheral surface of the hemi-cylindrical projection.  
           [0016]    A fifth aspect of the invention resides in a method of forming a bearing comprising: forming an essentially cylindrical sleeve; cutting an end portion of the sleeve to remove a hemi-cylindrical portion and to leave a hemi-cylindrical portion extending axially from a remaining cylindrical portion.  
           [0017]    A sixth aspect of the invention resides in a method of connecting a roller element bearing to a shaft comprising: forming a hemi-cylindrical projection on the end of a cylindrical sleeve which is integral with a inner roller of the bearing; and clamping the hemi-cylindrical to the shaft using a clamp having first and second halves wherein the first half has a first curved surface adapted to seat on a peripheral portion of the shaft and a second half having a second curved surface adapted to seat on an external surface of the hemi-cylindrical portion, and wherein drawing the first and second halves together so that the first surface is forced against the peripheral portion of the shaft and the second surface is forced against the external surface of the hemi-cylindrical clamps the shaft to the sleeve.  
           [0018]    With the selected embodiments of the invention a finished envelope size no greater than that of the conventional setscrew bearing design, is enabled. In one embodiment, no special tools are necessary to secure the bearing to the shaft—an ordinary torque wrench can be utilized. The assembly cannot be over-tightened causing damage to the bearing or its normal rated function. In the case of an expansion bearing embodiment, maintainers can easily make adjustments. No flats or other special surface preparation commonly required to secure the setscrews, is required in this embodiment.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]    The various features and advantages of the present invention will become more clearly appreciated as a detailed description of the preferred embodiments is given with reference to the appended drawings in which:  
         [0020]    [0020]FIGS. 1A and 1B are views of a bearing and a setscrew type clamp arrangement in a disassembled state;  
         [0021]    [0021]FIG. 2 is a perspective view of the bearing arrangement depicted in FIGS. 1A and 1B, in an assembled state;  
         [0022]    [0022]FIG. 3 is a sectional view of a spherical bearing which is provided with a tapered sleeve/race arrangement;  
         [0023]    [0023]FIG. 4 is a perspective view of a bearing, shaft and clamp arrangement according to an embodiment of the invention;  
         [0024]    [0024]FIG. 5 is a second perspective view of the bearing, shaft and clamp arrangement shown in FIG. 3;  
         [0025]    [0025]FIGS. 6A and 6 b  are respectively schematic perspective views showing sleeve variants used in the embodiment of the invention;  
         [0026]    FIGS.  7 A- 7 C are respectively front elevation, plan and side elevation of a clamp used in the embodiments of the present invention;  
         [0027]    [0027]FIG. 8 is a side view of the embodiment of the bearing which is provided with the sleeve arrangement depicted in FIG. 6B;  
         [0028]    [0028]FIG. 9 is a perspective view of the bearing arrangement shown in FIG. 8;  
         [0029]    [0029]FIG. 10 is a perspective view similar to that shown in FIG. 8 with the shaft disposed in the sleeve of the bearing;  
         [0030]    [0030]FIGS. 11A and 11B are respectively a side view of the bearing according to the embodiment of the invention and a front view of the clamp in a dissembled state;  
         [0031]    [0031]FIG. 12 is a end view of the bearing showing the clamp secured to the shaft and hemi-cylindrical portion of the sleeve; and  
         [0032]    [0032]FIGS. 13 and 14 are perspective views of the embodiment of the present invention which show the clamp disposed in position. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0033]    FIGS.  4 - 14  show an embodiment of the present invention. In this arrangement a bearing  100 , which, in this instance, takes the form of a spherical bearing, is clamped to a shaft  101  via a sleeve and clamp arrangement generally denoted by the numeral  104 . The bearing  100 , of course includes inner and outer races and roller elements typically enclosed in a housing having a mounting flange, one variant thereof being shown as item  105  in FIGS. 13 &amp; 14.  
         [0034]    In order to render the bearing/clamp arrangement compact, it is preferred to seat the clamp  104  flush against the bearing collar.  
         [0035]    As best seen in FIG. 6A the sleeve  106  is formed so as to have a cylindrical portion  106 A and a coaxially extending hemi-cylindrical portion or projection  106 B. This sleeve  106  can be either unitarily formed with the inner race of the bearing or connected thereto so as to be integral and therefore synchronously rotatable with the inner race.  
         [0036]    As seen in FIGS. 5 and 7 the clamp  108  comprises of first and second halves which shall be referred to respectively as “upper” and “lower” halves  108 A and  108 B. The upper half  108 A has an inner curved surface  108 A-CS having an inner diameter selected to coincide with the outer diameter of the shaft  101  which is to be clamped in the bearing  100 . The lower half  108 B has a curved inner surface having an inner diameter selected to coincide with the outer diameter of the hemi-cylindrical portion  106 . Thus, when the two halves  108 A,  108   b  are assembled, they engage the shaft  101  and the hemi-cylindrical portion  106 B in the manner depicted in FIGS. 5 and 7, for example.  
         [0037]    By drawing the upper and lower halves  108 A,  108 B of the clamp together using socket head cap screws  110  or the like, the upper half  108 A grips the shaft  101  in a manner which produces a first surface-to-surface contact while the lower half  108 B grips the hemi-cylindrical portion  106 B in a manner which produces a second surface-to-surface contact. The force applied to the hemi-cylindrical portion  106 B forces it into engagement with a portion of the shaft  101  not contacted by the upper half  106 A.  
         [0038]    As will be noted, the upper and lower halves  108 A and  108 B of the clamp are dimensioned so that the juxtaposing faces establish design gaps D/G which allow the halves to be tightended down without contact/interference between the two halves that might limit the degree to which they can be drawn together.  
         [0039]    Under these conditions, relative rotation between the shaft  101  and the sleeve  106  is securely prevented. Repeated disconnection and re-connection of the shaft and the bearing can be accomplished without the need to use new parts or to exercise excessive care when torquing the two halves together.  
         [0040]    In order to prevent any flexure and/or distortion of the hemi-cylindrical portion  106 B from being transmitted through the cylindrical portion  106 A of the sleeve  106  and inducing undesirable changes in the clearances defined between the rolling elements and the inner and outer race members of the bearing  100 , a variant of the sleeve is, as shown in FIG. 6B, provided with slots  106 S which extend perimetrically with respect to the hemi-cylindrical portion  106 B, allow for the flexure of the hemi-cylindrical portion  106 B with respect to the main cylindrical portion  106 A and essentially eliminate any effect of the flexure of the hemi-cylindrical portion  106 B against the shaft  101 , being transmitted via the cylindrical portion  106 A to the inner race of the bearing  100  in a manner which causes any changes in the spatial relationship between the rolling elements and the inner and outer race members from occurring. The slots are formed in the sleeve so as to be located outboard of the lubricant seals of the bearing so as to avoid any compromise of their efficiency.  
         [0041]    Another distortion reducing structure which attenuates/prevents distortion of the hemi-cylindrical portion  106 B of the sleeve being transmitted back through the cylindrical portion  106 A into the bearing proper in a manner which causes clearances in the bearing to deviate from their preferred ranges, takes the form of a pair of recesses  108 B-R which are formed at the opposite ends of the curved surface  108 B-CS of the lower half  108 B. These recesses  108 B-R form a pair of clearances C/L which, as best seen in FIG. 12, reduce the arc A/R through which force is applied to the hemi-cylindrical portion  106 B of the sleeve. This attenuates transmission of distorting forces from the hemi-spherical portion to the cylindrical portion and the inner race as the clamp is applied and thus achieves an effect similar to that provided with the slots  106 S in the sleeve and can be used in lieu of the slots  106 S.  
         [0042]    [0042]FIGS. 13 and 14 show the bearing  100  enclosed in the housing  105  having a mounting flange via which the bearing can be secured to a frame or chassis of a machine or the like of which the shaft  101  forms an operative element.  
         [0043]    When constructing the bearing, the sleeve can be cut and/or machined to have the hemi-cylindrical projection, and/or slots prior to annealing/hardening. This renders the metal softer and easier to machine. A further variant of the sleeve can include forming the second or lower part of the clamp so as to be integral and/or unitary element with the hemi-cylindrical projection. This formation, if so desired, can also be implemented prior annealing/hardening.  
         [0044]    Although the invention has been described with reference to only a limited number of embodiments, it will be understood that, given the preceding disclosure and the concepts that can be distilled therefrom, a person skilled in the art to which the present invention pertains or most closely pertains, would be able to readily envisage the variants and changes that are possible without departing from the scope of the appended claims.  
         [0045]    For example, while only two arrangements are disclosed for preventing distortion being transmitted back into the bearing proper in a manner which invites a disturbance of the preferred spatial relationship between the rolling elements and the inner and outer races, it is within the scope of the invention to use both in combination and/or provide other structures which provide a similar function. For example, drill holes can be used in place of the slots or a groove or grooves can be formed in locations to permit flexure of the hemi-cylindrical portion of the bearing with respect to the main body thereof so that distortion of the main body is essentially eliminated. Similarly a hinged clamp may be used in place of a 2-piece split clamp.  
         [0046]    In addition to the above, it is also possible to provide a pin which is pressed into the lower half  108 B of the clamp and to provide a hole in the hemi-cylindrical projection  106 B in which the pin can register and thus facilitate the positioning of components during clamp assembly.