Abstract:
A bearing assembly for rotatably supporting a shaft member having an outer ring, having a first bearing raceway, and an inner ring, having a second bearing raceway. The raceways are opposingly spaced relative to each other. The inner ring includes a plurality of tang members extending in a cantilevered configuration from at least one end of the inner ring having slots formed therebetween. Bearing members are positioned in a space between and in engagement with the first and second bearing raceways. An undercut groove extends circumferentially along an inner surface of the inner ring generally adjacent the plurality of tang members. The undercut groove is operable to increase an effective cantilever distance of the plurality of tang members. The assembly further includes a locking member engaging the plurality of tang members and exerting a compressing force upon the plurality of tang members to couple the inner ring to the shaft.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit and priority of India Patent Application No. 3206/MUM/2013, filed Oct. 10, 2013. The entire disclosure of the above application is incorporated herein by reference. 
       FIELD 
       [0002]    The present disclosure relates to bearing assemblies and, more particularly, relates to bearing assemblies having an inner ring with an undercut to provide improved tang flexibility. 
       BACKGROUND AND SUMMARY 
       [0003]    This section provides background information related to the present disclosure which is not necessarily prior art. This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. 
         [0004]    Various arrangements are known in the art for securing the inner bearing ring of a bearing assembly onto a rotating shaft. Such arrangements have included shaft engaging set screws and shaft-surrounding locking collars. Such locking collars include locking or tightening means, generally in the form of one or more locking screws. In the arrangement disclosed in U.S. Pat. Nos. 4,537,519 and 6,908,230, which are hereby incorporated herein and made a part of the present teachings, a bearing assembly is provided wherein the inner ring includes equally spaced inner ring finger extensions or tangs which, when locked with a single screw locking collar, serves to grip and hold a shaft and the inner ring tightly in position allowing improved concentricity of the inner ring with the shaft and higher shaft speeds. 
         [0005]    The present teachings can be utilized in combination with any one of a number of known force applying arrangements for securing a bearing assembly to a shaft and are particularly adaptable to the compressible collar and inner ring finger extensions of the known SKWEZLOC® arrangement resulting in the aforementioned advantages of improved shaft-ring concentricity and increased capacity for locking under high loads and high speed shaft operations. 
         [0006]    Generally, these bearing assemblies are provided for use with a shaft that passes through the bearing assembly. Specifically, the bearing assembly may include an annular inner ring having a grooved raceway which is wear hardened to extend the bearing life. Surrounding the annular inner ring in spaced relation therefrom, is an annular outer ring having a grooved raceway disposed therein in opposed relationship to the inner ring raceway. The raceways serve to receive in nesting relationship therewith a plurality of spaced ball or rolling elements mounted in rolling element pockets of a rolling element cage. A lubricating passage is provided in the outer bearing ring which is aligned with a passage in bearing assembly housing or pillow block in which bearing assembly is mounted. To seal the rolling element cage assembly, annular inner flingers and outer flingers with annular seals therebetween are press-fitted respectively on the outer and inner bearing rings on either side of the loaded rolling element cage. In this way, the rolling elements can provide reduced frictional rotation of the shaft relative to the bearing assembly while rotating in the hardened raceways of the inner and outer rings. 
         [0007]    The inner ring may include the aforementioned inner ring finger extensions or tangs that project from the inner ring and surround the shaft. These finger extensions or tangs are then collapsed to some extent around the shaft to define the concentricity of the now-combined assembly. 
         [0008]    However, through recent analysis, it has been found that in some applications where shafts of commercial grade are used, which may lack the turned ground and polished finish of a higher grade shaft, may result in an out of concentricity of the combined inner ring and shaft assembly. That is, use of lower grade shafts having reduced tolerance demand may require that the inner ring finger extensions or tangs accommodate a greater degree of deflection and/or require that the inner ring finger extensions or tangs accommodate a varying degree of deflection from one extension to another extension. However, it has been found that as a result, at least in part, of this greater degree of deflection and the varying degree of deflection from one extension to another extension, the bearing raceway can become distorted upon installation of the locking collar. This can further lead to inconsistent raceway dimensioning between the inner ring and the outer ring causing reduced bearing performance and lifespan. 
         [0009]    The present teachings provide an improved inner ring configuration of a bearing assembly capable of accommodating a greater degree of shaft variations and further inhibit raceway deformation. Moreover, the present teachings provide an improved inner ring configuration that is be easily manufactured to provide the benefits of improved concentricity to a greater range of shaft dimensions and conditions. Moreover, the present teachings provide an inner ring configuration that is capable of reducing ball path deformation of the bearing raceway for improved operation and wear. 
         [0010]    Accordingly, a bearing assembly for rotatably supporting a shaft member having advantageous construction is provided according to the principles of the present teachings. The bearing assembly includes an outer ring, having a first bearing raceway, and an inner ring, having a second bearing raceway. The raceways are opposingly spaced relative to each other. The inner ring includes a plurality of tang members extending in a cantilevered configuration from at least one end of the inner ring having slots formed therebetween. Bearing members are positioned in a space between and in engagement with the first and second bearing raceways. An undercut groove extends circumferentially along an inner surface of the inner ring generally adjacent the plurality of tang members. The undercut groove is operable to increase an effective cantilever distance of the plurality of tang members. The assembly further includes a locking member engaging the plurality of tang members and exerting a compressing force upon the plurality of tang members to couple the inner ring to the shaft. 
         [0011]    Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
     
    
     
       DRAWINGS 
         [0012]    The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
           [0013]      FIG. 1  is a perspective view illustrating a bearing assembly according to the principles of the present teachings; 
           [0014]      FIG. 2  is a cross-sectional view illustrating an inner ring having an undercut groove according to the principles of the present teachings; 
           [0015]      FIG. 3  is a cross-sectional view, with portions removed for clarity, illustrating the bearing assembly according to the principles of the present teachings; 
           [0016]      FIG. 4  is an enlarged cross-sectional view illustrating the inner ring having an undercut groove according to the principles of the present teachings; 
           [0017]      FIG. 5  is an enlarged cross-sectional view illustrating the wear hardened region of the inner ring; 
           [0018]      FIG. 6A  is a cross-sectional view illustrating an inner ring having an undercut groove according to some embodiments of the present teachings; and 
           [0019]      FIG. 6B  is a cross-sectional view illustrating an inner ring having an undercut groove according to some embodiments of the present teachings. 
       
    
    
       [0020]    Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
       DETAILED DESCRIPTION 
       [0021]    Example embodiments will now be described more fully with reference to the accompanying drawings. 
         [0022]    Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. 
         [0023]    The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed. 
         [0024]    When an element or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
         [0025]    Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments. 
         [0026]    Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. 
         [0027]    According to the principles of the present teachings, a bearing assembly  10  having an advantageous construction is illustrated in the associated figures and described herein. With particular reference to  FIGS. 1-3 , the bearing assembly  10  is configured for use with a shaft member  12  ( FIG. 3 ). More particularly, bearing assembly  10  can comprise a bearing housing  14  having an annular inner ring  16  rotatably disposed within an outer ring  18  within bearing housing  14 . Inner ring  16  can be, at least indirectly, supported for rotation with shaft member  12  by a plurality of bearing members or other anti-friction members  20  positioned about an exterior side of inner ring  16  and an interior side of outer ring  18 . In this way, the plurality of bearing members  20  can be positioned within a circumferential raceway  22  extending between inner ring  16  and outer ring  18 . Specifically, raceway  22  can comprise a grooved raceway  24  formed circumferentially along an outer surface of inner ring  16  and an opposing grooved raceway  26  formed circumferentially along an inner surface of outer ring  18 . Grooved raceway  24  of inner ring  16  and grooved raceway  26  of outer ring  18  are in spaced relationship to each other to define raceway  22 . In some embodiments, grooved raceway  24  and/or grooved raceway  26  are wear hardened for improved bearing life and operation. In some embodiments, the plurality of bearing members  20  can be captured within a bearing cage  25 . 
         [0028]    In some embodiments, one or more seal members  28  can be used to engage opposing ends of inner ring  16 , outer ring  18 , bearing members  20 , and/or bearing housing  14  to retain a lubricant (e.g. grease) within a volume containing bearing members  20 . Lubricant can be inserted with this volume via a grease fitting  30  ( FIG. 3 ). 
         [0029]    With particular reference to  FIGS. 1-4 , inner ring  16  includes a plurality of tang members  32  extending therefrom in annular cantilever fashion to surround shaft member  12 . Tang members  32  are provided with a plurality of slots  34  parallel the axis of shaft rotation to permit radial compression by a surrounding slotted locking collar  36 . It should be understood, however, that alternative locking force arrangements besides collar  36  can be used. 
         [0030]    With continued reference to  FIGS. 1-4 , in some embodiments, inner ring  16  further comprises an undercut groove  40  extending along an inner surface  42  of inner ring  16 . Undercut groove  40  can extend circumferentially about inner surface  42  of inner ring  16  to define a complete and continuous groove. Undercut groove  40  can be positioned generally adjacent and/or intersecting proximal end  44  of slots  34 . Undercut groove  40  can serve, at least in part, to extend the effective cantilever beam length of tang member  32 , thereby providing improved beam deflection range without increasing the width of inner ring  16  nor impinging on a hardened area of grooved raceway  24  of inner ring  16 , as will be discussed in greater detail herein. 
         [0031]    By way of background, with particular reference to  FIG. 4 , it should be understood that existing inner ring designs having finger extensions or tangs have an actual tang length X, which extends from an abutment face or shoulder  46  of the inner ring to a distal end  48  of the tang. As can be appreciated, this reduced actual tang length X results in minimal tang deflection capability which directly limits the ability of the plurality of tangs to accommodate varying shaft member dimensions as discussed herein. However, in accordance with the present teachings, the addition of undercut groove  40  increases the effective tang length to Y, which extends from distal end  48  of tang  32  to an inboard or proximal side  50  of undercut groove  40 . This increased effective tang length Y provides improved ability of tangs  32  to accommodate varying shaft member dimensions and out-of-round conditions. 
         [0032]    As can be appreciated with reference to  FIGS. 4 ,  6 A, and  6 B, undercut groove  40  can comprise any one of a number of cross-sectional configurations when viewed along a plane parallel to the axis of rotation of shaft member  12 . Specifically, in some embodiments, undercut groove  40  can comprise a generally arcuate groove shape having generally parallel edges—namely proximal side  50  and distal side  52 . Sides  50 ,  52  can extend from inner surface  42  to a terminal arcuate surface  54  within undercut groove  40 . Alternatively, in some embodiments as illustrated in  FIG. 6A , sides  50 ,  52  can extend from inner surface  42  to inner chamfers  56  and an inner planar surface  58 . Inner planar surface  58  can be generally flat. Similarly, in some embodiments as illustrated in  FIG. 6B , sides  50 ,  52  can extend from inner surface  42  to inner planar surface  58  (without inner chamfers  56 ). Moreover, it should be recognized that the specific size and dimensions can vary depending on operation and intended conditions. For instance, as illustrated in  FIG. 6B , the width and depth of undercut groove  40  can vary. 
         [0033]    It should be understood that undercut groove  40  can have any cross-sectional geometry, such as rectangular, semicircular or trapezoidal, provided the feature removes material from the inner ring and isolates the tang region. 
         [0034]    However, in some embodiments, various dimensional relationships result in a beneficial compromise and improved operation. Specifically with reference to  FIG. 4 , in some embodiments, it has been found that the following dimensional relationship results in relieving stresses in the region of tang  32 . That is, the dimension A, which is the minimum thickness extending between undercut groove  40  and abutment surface  46 , can be generally equal to dimension B, which is the minimum thickness of tang  32  taken along a direction orthogonal to the axis of rotation of shaft member  12  generally a reduced-thickness section of tang  32 . By ensuring dimensions A and B are generally equal to each other, the depth F of undercut groove  40  is established which results in relieve stresses in tang  32 . 
         [0035]    Furthermore, in some embodiments, it has been found that the following dimensional relationship results in improved operation of undercut groove  40  without negatively impacting the reliability of wear hardened bearing raceway  24  of inner ring  16 . As discussed herein, it is desirable to wear harden bearing raceway  24  of inner ring  16  to improve bearing life and operation. Wear hardening of bearing raceway  24  results in a region  60  of hardened material generally denoted by cross-sectioning in  FIGS. 4 and 5 . Hardened region  60  can define an edge-to-edge width along outer surface of inner ring  16  of dimension Z ( FIG. 5 ). Hardened region  60  can further define an edge-to-edge width along inner surface  42  of inner ring  16  that is less than dimension Z, generally resulting in an inwardly tapered cross-section. With reference to  FIG. 4 , a width E of undercut groove  40  can be determined in connection with dimension Z of hardened region  60  and an offset distance C between distal point  62  of hardened region  60  and proximal side  50  of undercut groove  40  (it should be noted that distance C is measured along a single axis parallel to the axis of rotation of shaft member  12  (e.g. axial direction)). Specifically, dimension C can be greater than or equal to a constant K times dimension E. Dimension C thus represents a minimum spacing distance before proximal side  50  of undercut groove  40  and hardened region  60 , which in turn limits the width E of undercut groove  40 . This arrangement inhibits, or at least reduces, the negative effect on raceway  24  of inner ring  16  following application of locking collar  36  about tangs  32 . Therefore, raceway  24  can maintain a proper cross-sectional shape and spacing from opposing raceway  26 , thereby providing improved bearing life and operation. In some embodiments, constant K can be approximately 0.6 for smaller applications. 
         [0036]    It should be understood that the cross-sectional shape of undercut groove  40  can affect the heat treatment process of inner ring  16  following initial machining. In some cases, improper dimensioning of inner ring  16  can result in internal cracks within inner ring. Therefore, it has been found that in applications employing heat treatment, dimension C should also be at least half of dimension Z to provide sufficient standoff distance to ensure proper heat treatment. 
         [0037]    Referring again to  FIG. 3 , in some embodiments, the width of collar  36  is substantially equal to the length X of tang members  32 , which facilitates collar mounting during assembly to assure aligned seating or squaring of collar  36 . However, it should be understood that collar  36  may define a greater or lesser width dimension. 
         [0038]    In some embodiments, tang members  32  can comprises an circumferential groove or recess  64  extending circumferentially around the outer surface of tang members  32  in spaced relation from distal end  48 . In some embodiments, the width of recess  64  is approximately one half the width of locking collar  36 . 
         [0039]    According to the principles of the present teachings, the bearing assembly and, more particularly, the inner ring permits increased deflection of the tang members and thus is capable of accommodating a greater tolerance range of shaft members without negatively impacting the roundness value of the bearing raceway, thereby providing a greater range of acceptable shaft member dimensions while maintaining reliable and efficient bearing operation. This configuration results in improved bearing life and performance. 
         [0040]    Furthermore, the principles of the present teachings provide a number of advantages over the prior art, such as, but not limited to, increased tang deformation, improved shaft holding capacity, and reduced out of roundness at raceway due to locking. This results in reduced vibration and noise generated by the bearing assembly. This further permits accommodating commercial grade shaft members that have not been turned ground and/or polished, which reduces manufacturing and assembly costs. 
         [0041]    The principles of the present teachings can be used in all collar locking applications where raceway roundness is a key parameter and in applications requiring increased effective tang length without the need to physically increase the overall length of the inner ring. 
         [0042]    The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.