Patent Publication Number: US-2007120416-A1

Title: Wheel assembly

Description:
FIELD OF THE INVENTION  
      This invention relates to a relatively light weight, wheel structure of the type which can be used as a caster wheel, such as for load carrying trolleys, and is particularly suitable for use as a gauge wheel on agricultural equipment, such as headers for swathers, combines and the like.  
     BACKGROUND OF THE INVENTION  
      A common form of gauge wheels utilized on combine headers are modified wheels which are commercially available for other industrial applications, such as fork lifts. These wheels are generally of a heavy duty build, and thus are not only expensive but add to the implement unnecessary weight which for a number of reasons is undesirable.  
     SUMMARY OF THE INVENTION  
      It is an object of the present invention to provide a light weight wheel structure which is of relatively low cost and provides sufficient structural strengths for satisfactory operation under rather adverse working conditions.  
      According to one aspect of the present invention there is provided a wheel structure which includes a hub member having a cylindrical outer surface extending between opposite end surfaces and being of substantially constant cross-section configuration throughout the length thereof, the cross-sectional configuration defining a plurality of openings extending longitudinally through the hub member. There are also provided a pair of end plates having inner surfaces abutting the opposite end surfaces of the hub member with a plurality of fasteners, one each extending through the plurality of openings and applying forces against the end plates for drawing the inner surfaces of the end plates against opposite end surfaces of the hub member.  
      In a preferred embodiment of the invention, the hub member is formed as an extruded body of aluminum.  
      According to another aspect of the invention there is provided a wheel structure including an elongated hub member of extruded material having a cylindrical outer surface and being of constant cross-section configuration throughout substantially the length thereof, and wherein the cross-sectional configuration defines a plurality of openings extending longitudinally through the hub member between opposite ends thereof. A pair of end plates are included, each having an outer edge extending peripherally about inner side surfaces. The hub member has opposite end surfaces defined in a recessed area in the opposite ends and surrounded by a circumferential rim flange shaped to engage the outer edges of the end plates. The wheel structure further includes a plurality of fasteners applying a force against the end plates for holding the inner side surfaces of the end plates against the opposite end surface of the hub member and within the recessed area.  
      Yet another aspect of the invention is in the form of a hub member for use in fabricating a wheel structure, the hub member including an extruded body having opposite plate engaging end surfaces disposed normal to an longitudinally extending axis of the body, the extruded body being of constant cross-sectional configuration throughout a length thereof extending between the end surfaces and defining longitudinal extending, fastener receiving openings therethrough, the body being of circular shape in cross-section providing an outer tire mounting cylindrical surface.  
      The present invention also resides in a method of making a wheel structure of the type having a wheel hub member by first providing a core element defined within by an outer cylindrical tire supporting surface extending between opposite ends which provide seating areas for bearing mounting plates. The method includes the steps of forming by extrusion of a material through a die, the extrusion providing a continuous length of hub stock having at least a central opening extending longitudinally therethrough, and then cutting a hub member from the length of hub stock, prior to machine squaring opposite ends of the hub member to the required length of the individual wheel hub. There is then formed in the opposite ends of the wheel hub seating areas for attaching bearing supporting elements coaxially within the central opening of the hub stock.  
      Preferably the material utilized as the extruding material is aluminum. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
      In the accompanying drawings, which show specific embodiments of the invention as examples,  
       FIG. 1  is a perspective view of one embodiment of an assembled wheel structure of the present invention;  
       FIG. 2  is a side view of the wheel structure of  FIG. 1 ;  
       FIG. 3  is a cross sectional view of the wheel structure as seen from line  3 - 3  of  FIG. 2 ;  
       FIG. 4  is a perspective view of an extruded length of a hub core stock of the present invention for use in forming a hub member of the wheel structure as shown in FIGS.  1  to  3 ;  
       FIG. 5  is a perspective view of a core element as severed from the continuous core stock shown in  FIG. 4 ;  
       FIG. 6  is arm end view of the core element shown in  FIG. 5 ;  
       FIG. 7  is a view of the core element similar to that of  FIG. 5 , but as squared and counterbored for the subsequent preparation of a finished wheel structure;  
       FIG. 8  is an exploded view of the wheel structure of FIGS.  1  to  3 ;  
       FIG. 9  is a side view of another embodiment of the invention and showing the wheel on a mounting framework;  
       FIG. 10  is a rear view of the wheel structure as shown in  FIG. 9 ; and  
       FIG. 11  is a sectional view of the wheel structure as seen from line  11 - 11  of  FIG. 10 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      In the drawings, the wheel assembly of the present invention is denoted generally by the reference number  20 , and as will become more apparent in the description below, the wheel assembly  20 , includes a basic component which is a hub member  21 , preferably formed as an extruded and subsequently machined body as shown most clearly in  FIG. 7 .  
      In an assembled condition of the wheel assembly  20 , end plates  22 , 22  are secured to opposite ends  23 , 23  of the hub member  21  by fasteners  24 . The hub member  21  provides between its opposite ends  23 , 23  a cylindrical outer surface  26  ( FIG. 3 ) to which is affixed a tire  27 . In the embodiment shown in FIGS.  1  to  8 , the end plates define a central opening within an in-turned flange  30 .  
      Second or outer plates  25  having inner faces  28  ( FIG. 3 ) are held against outer faces  29 , 29  of the end plates  22 , 22  by the same fasteners  24 , and the outer plates  25  have out-turned flanges  31  which define therewith a central opening coaxial with the central opening of the end plates  22 , 22 . As will become more apparent below, the in-turned flanges  30  of each end plate  22  and the out-turned flanges of the outer plate  25  together provide a bearing cage for supporting an axle containing bearing as described in more detail below.  
      The nature of the hub member  21  is of significance, and reference to FIGS.  4  to  7  is made to facilitate an understanding of its formation. A particular cross-sectional configuration is selected to provide the required endurance and assembling characteristics of the hub member  21 . While various methods, such as casting, injection molding, sintering, etc. could be used to form the hub member  21 , it is believed more feasible to form a continuous element of hub stock  33  ( FIG. 4 ), which has a selected cross-section configuration and is extruded to a length which is a number of times the length of a separate hub core member  34  ( FIG. 5 ) for use in forming the final hub member  21 . The cross-sectional configuration of the hub stock  33  is consistent, of course, throughout its length by this forming process. In a wheel structure for the use described below, the material which appears most desirable both in relation to cost and endurance is aluminum. It is possible for economical and/or other requirements for different wheel structures, to use other materials, including metal alloys and extrusible plastics, which may be more feasible. Moreover, the configuration of the cross-section could be varied for different applications. With respect to the particular cross-sectional configuration of the core member  34  ( FIGS. 5 and 6 ), various characteristics may be considered, including the amount of material to be used, strength, weight and structural features, such as those which are feasible for the attachment of additional parts to form the complete wheel structure.  
      The extrusion process does provide, of course, the continuous and uniform cylindrical outer surface  26  extending between the opposite outer ends of each core member  34  cut therefrom. The peripheral part or rim portion  35  of the core member  34  may be relatively thin in relation to the overall radius of the hub core cylindrically shaped member  34 , and the rim portion  35  is joined to a central axial portion  36  by a plurality of longitudinally continuous radial webs  37 . A plurality of longitudinally continuous ribs  40  are formed integrally on an inner surface of the rim portion  35  between the radial webs and extend the length of the core member  34 . The purpose of the ribs  40  is, among other reasons, to reinforce the strength of rim portion  35 . At the juncture of the webs  37  with the central axial portion  36 , enlargements  41  are formed to provide longitudinally extending openings  41  which are generally of circular cross-sections to receive the fasteners  24  as will be described further below. A central opening  38  provided by the central axial portion  36  extends, of course, the full length of the hub core member  34 , as do the openings  42 .  
      In the preparation of the hub member  21  ( FIGS. 5 and 6 ) for assembly into a completed wheel assembly  20 , the hub core member  34  is severed from the length of extruded hub stock  33  ( FIG. 4 ). It may be then machine squared at opposite ends to provide opposite ends  23 , 23  of the hub member  21  in parallel planes to which the central axis of the hub member is normal. The ends  23 , 23  are then machined to provide counterbores to form recessed end surfaces or areas  43 , 43  ( FIG. 3 ) inward of the outermost ends  23 , 23  of the hub member  21 . In forming the recessed areas, the counterbore is selected in diameter to remove the innermost part of the rim portion  35  of the hub core member  34  as well as the outermost ends of the radial webs  37 , hub portion  36 , and ribs  40 , so that a recessed shoulder  44  is provided within an outer circumferential rim flange  45 . The recessed shoulder  44 , of the rim portion  35 , and the ends webs  37 , ribs  40  and central axial portion  36  are all in the same recessed plane which forms the recessed areas  43 , 43  normal to the axis of the hub member.  
      Prior to assembling the wheel structure, an elastomeric material, preferably rubber or polyurethane is molded, vulcanized or otherwise bonded to the outer surface of the hub member  21  to form the tire  27 . As shown in  FIG. 3 , for example, the tire is of solid configuration and has a slightly curved outer surface and more sharply curved outer corner edges.  
      The end plates  22 ,  22  in the embodiment of the invention as seen in  FIGS. 3 and 8  are preferably formed of plate steel and may be made as a stamped part to provide the in-turned flange  30  to form a bearing cage with the out-turned flange  31  or outer plate  25 . The disks  22 , 22  have outer peripheries  46 , 46  which are of a diameter to fit closely within the internal circumference of the rim flange  45 . When assembled the end plates are pulled tightly into the counterbore so that the inner surfaces  32 , 32  thereof tightly engage machined recessed shoulders  44  as well as the ends of the central axial portion  36 , webs  33 , and ribs  40 , all of which are in the same plane thus forming the recessed areas  43 , 43 . The fasteners  24  in the illustrated embodiments include three bolts  47  of the type having carriage heads  50  with the opposite ends being threaded at  51  to receive nuts  52 . The end plates  29 , 29 , have three bolt receiving holes  53 , while the outer plates also have three bolt receiving holes  54 , the holes  53  and  54  being on the same radius and of the same spacing as the longitudinal openings  42  through the hub member  21 . Thus, the aligned holes receive bolts  47  prior to the nuts  52  being tightened to bring the end plates  22 , 22  into tight engagement with the recessed areas  43 , 43  at the opposite ends of the hub member  23 , and to also bring the inner surfaces  28 , 28  and the outer plates into tight engagement with the outer surfaces  29 , 28  of end plates  22 , 22 . As shown, the holes  53  and  54  in the end plates  22  and outer plates  25  respectively, are of square configuration so as to receive the squared head portion of the carriage bolts  47  in order to facilitate assembly of the overall wheel structure.  
       FIG. 8  shows the parts present for a more final form of a wheel assembly. As previously described, the in-turned flange  30  of each end plate  22  and the out-turned flange  31  of its associated outer plate  25  provide a bearing seat. To install a bearing  55  within this seat, once the end plates have been brought into position an inner tubular axle member  56  having opposite ends for extending respectively through the inner races  57  of a pair of the bearings  55 , 55  is positioned within the central opening  38 . The bearings are then slid over the opposite ends of the tubular member, and outer races  58 , 58  of the bearings thus being installed are brought into contact with the in-turned flanges  30  of the outer plates  22 , 22 . The outer plates  25 , 25  are then brought against the outer surfaces  29 , 29  of the end plates with the out-turned flanges  31 , 31  then engaging the outer races  58 , 58  as the bolts are tightened so as to entrap the bearings  55 , 55  in a seated position between the flanges  30 , 31  of the end plates  22 , 22  and the outer plates  25 , 25 .  
      There is shown in FIGS.  9  to  11  a slightly modified form  20 ′ of a wheel structure, there also being illustrated a more detailed manner of mounting the wheel structure as used, for example, on an implement such as a harvesting header. The wheel is mounted in a framework  59  between a pair of spaced, downwardly depending leg members  60 , 69 , which are joined at upper ends to a transverse member  61 . The framework  59  further includes a mounting plate  62  adapted to bolt the framework  59  to a swivel type mechanism for connecting to a header structure so as to allow the wheel structure to operate as a gauge wheel for partially supporting outer ends of a header (not shown) to thereby controlling its height above the ground surface on which the wheel structure rides. As most clearly shown in  FIG. 11 , the wheel assembly  20 ′ is mounted in the framework  59  by way of an axle bolt  64  which extends through openings  65 , 65  of the leg members  60 , 60 . The bearings  55 , 55  are of a type in which the inner race  57  has an extension  63  formed integrally at one side thereof. The extension has set screws  70  screwed into threaded bores therein so that on tightening of the screws  70 , the inner races  57 , 57  are affixed to the bolt  64  and thereby establish a fixed position of the wheel assembly relatively to the axle forming bolt. Nut  66  is threaded onto bolt  64  and abuts the outside of one of the leg members  60 , while a head  71  of bolt  64  engages the outside of the other leg member  60 .  
      The entire structure of the hub member  21  shown in wheel assembly  20 ′ may be identical to that shown in the previously described embodiment, and this is also the case for outer plates  25 , 25 . Also while the fit of end plate  22 ′ within the recessed end areas of the hub member is the same as in the earlier embodiment, the design of the end plate structure may be in a form which allows a less expensive structure in that the end plate may be simply cut or formed from flat sheet of metal, such as steel or aluminum, without having to press or otherwise form an in-turned flange  32  to provide part of the bearing cage. Instead, for each bearing cage there is simply used a second outer plate  25 , but as shown in  FIG. 11  this plate is designated as secondary outer plate  67 . As illustrated, the secondary outer plate  67  is reversed so that the surface previously designated as the inner face  28  of the outer plate  25  becomes the outer face  69  of the secondary outer plate  67 , and the out-turned flange  31  of the outer plate  25  becomes an in-turned flange  30 ′ of the secondary outer plate  67 . The bolt  47  which is passed through the aligned openings of outer plate  25 , secondary outer plate  67 , and end plate  22 ′ at either side of the hub member  21  hold all members in tight engagement with the out-turned flange of the outer plate  25  and the in-turned flange  30 ′ of the secondary outer plate  67  providing the bearing cage.  
      It will be apparent that the generally hollow nature of the hub core member  34  and the fact it may be formed of a light metal, as well as the relatively small volume of steel used in the end plates  22  and outer plates  25 , provides a light weight structure. Moreover, because of the manner in which the end plates  22 , 22  are fitted within the recessed areas  43 , 43  good provision exists for transferring the load forces between the end plates and the rim portion of the hub member. The fit further prevents against soil and other debris from migrating to the interior of the wheel structure. Because of the simplicity of the forming and machining of the hub core member subsequent to the extrusion forming of the elongated hub stock and the need of a few additional components of non-complex form to complete the structure, the finalized structure is of competitive cost.  
      While specific embodiments have been presented for sake of explanation, variations within the scope of the spirit of the appending claims will be apparent to those skilled in the art.