Abstract:
A cam assembly is provided for adjustment of a drill feed guide wear pad. The cam assembly has an eccentric bushing with a shank portion extending circumferentially about a first axis and defining a bore along a second axis. The second axis is generally parallel and offset from the first axis. The bushing has a head portion extending from the eccentric bushing portion, with the bore extending though the head portion. The bushing is sized for insertion into an aperture of a drill feed guide wear pad, and is rotatable causing the shank portion to engage the aperture of the wear pad to provide a camming action to position the wear pad relative to a drill feed guide. The head portion is shaped to interact with a tool for rotating the bushing.

Description:
TECHNICAL FIELD 
       [0001]    The invention relates to an adjustment system for wear pads of drill feed guides. 
       BACKGROUND 
       [0002]    Wear pads are used to maintain clearance gaps for parts or assemblies that are mounted to feed guides. A feed guide has many moving parts or assemblies that are attached to it such that they may move lengthwise along the long axis of the feed guide. Examples of the moving parts or assemblies for use with feed guides include rock drill mounting, hose reel or drum assemblies, and dust pots. 
         [0003]    Wear pads are placed between the feed guide and the moving parts or assemblies. Wear pads are adjusted the first time the part or assembly is installed onto the feed guide, and are adjusted periodically thereafter to minimize excessive movement of the parts or assemblies. Often, the wear pad is bolted with a pack of shims and then the wear pad is held in place while maintaining a preferred gap in two different directions at once. This process may be difficult or cumbersome and usually requires two workers to make an adjustment. 
       SUMMARY 
       [0004]    In one embodiment, a cam assembly is for adjustment of a drill feed guide wear pad. The cam assembly has an eccentric bushing with a shank portion extending circumferentially about a first axis. The bushing defines a bore along a second axis generally parallel and offset from the first axis. The eccentric bushing has a head portion extending from the eccentric bushing portion with the bore extending though the head portion. The bushing is sized for insertion into an aperture of a drill feed guide wear pad, and the bushing is rotatable causing the shank portion to engage the aperture of the wear pad, thereby providing a camming action to position the wear pad relative to a drill feed guide. The head portion is shaped to interact with a tool for rotating the bushing. 
         [0005]    In another embodiment, an adjustment fastener for a drill feed guide wear pad has an eccentric bolt having a head portion, a first shank portion and a second shank portion, with the first and second shank portions offset collinearly. The first shank portion is sized to fit within an aperture of a wear pad, and the second shank portion is sized to fit within the aperture of a mount. The bolt is rotatable such that the first shank portion engages the wear pad and the second shank portion engages the mount aperture thereby providing a camming action caused by the offset to position the wear pad. 
         [0006]    In yet another embodiment, a cam assembly for adjustment of a drill feed guide wear pad has an eccentric bushing having a head portion and a cylindrical body portion extending therefrom about a first axis. The head and body portions of the bushing define a bore along a non-collinear second axis of the bushing. The cam assembly has a fastener sized to fit within the bore to connect the eccentric bushing, a wear pad, and a mount. The body portion is sized for insertion into an aperture of the wear pad, and the bushing is rotatable causing the body portion to engage the aperture of the wear pad, thereby providing a camming action to position the wear pad. The head portion is shaped to interact with a tool for rotating the bushing. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  is a side section view of a wear pad system and feed guide according to the prior art; 
           [0008]      FIG. 2  is an exploded side view of the wear pad adjustment system of  FIG. 1 ; 
           [0009]      FIG. 3  is a side view of a wear pad adjustment system and feed guide according to an embodiment; 
           [0010]      FIG. 4  is a side view and a top view of the wear pad adjustment system; and 
           [0011]      FIG. 5  is a perspective view of a wear pad adjustment system and feed guide of  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION 
       [0012]    As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for the claims and/or as a representative basis for teaching one skilled in the art to variously employ the present invention. 
         [0013]      FIGS. 1 and 2  show a wear pad system  10 , feed guide  12 , and mounting slide  14  for use with a moving part or assembly  15  according to the prior art. The feed guide  12  has moving parts or assemblies  15  that are connected to the feed guide  12  through a mounting slide  14  to allow the moving parts  15  to move lengthwise along the long axis  16  of the feed guide  12 . The moving parts or assemblies  15  may be rock drill mounting, hose reel or drum assemblies, dust pots, or the like. The feed guide  12  has two opposing C-shaped channels  18  which are oriented such that the legs  20  of the C-shaped channels  18  oppose each other. 
         [0014]    The wear pad assemblies  10  secure the mounting slide  14  for a moving part  15  to the C-shaped channels  18  of the feed guide assembly  12  such that the slide  14  may move along the feed guide  12  longitudinal axis  16 . In one embodiment, the wear pad system  10  has two wear pads, a lower wear pad  22 , and an internal wear plate  24 , made of a wear resistant material as is known in the art. The wear pads  22 ,  24  are used to minimize or control the amount of movement of the parts or assemblies  15  attached to the mounting slide  14  along the longitudinal axis  16  by controlling the two gaps  26 ,  28 . The spacing between the feed guide  12  and the lower wear pad  22  provided by gaps  26 ,  28  allow for a common working axis  16 . 
         [0015]      FIG. 2  shows the wear pad system  10  according to the prior art. The wear pads  22 ,  24  are connected to the slide  14  by a traditional bolt  30 . The bolt  30  extends through the lower wear pad  22 , internal wear plate  24 , and through the mounting slide  14 . Gap  26  may be adjusted through use of a shim pack  32 . A washer  34 , bushing or the like may also be present between the lower wear pad  22  and the interior wear plate  24 . A nut  36  retains the bolt  30  in place, and an additional washer  34 , bushing, or the like may be used between the nut  36  and the mounting slide  14 . 
         [0016]      FIG. 3  shows an embodiment of wear pad assembly  50  connected to the mounting slide  14 . The wear pad assembly  50  has a bolt  52  or other like fastener as is known in the art that extends through the feed guide assembly  12  along a first axis  54 . The bolt has a head  56 , a first shank portion  58  and a second shank portion  60 . The head  56  and first shank portion  58  is offset and extends along a second axis  62  from the second shank portion  60 . At least a portion of the second shank  60  may be threaded such that a nut  64  or the like may be connected to the bolt  52 . 
         [0017]    The head  56  of the bolt  52  may be hexagonal, socket, adapted for use with a spanner wrench, or the like. The bolt  52  and a shim pack  66  and washer  68  with the desired thickness to provide a gap  70  are used to attach wear pads  22 ,  24  to the mounting slide  14  to interact with the feed guide  12 . The nut  64  is connected to the bolt  52  to retain it in place along with another washer  68 . The bolt  52  may be rotated such the first shank portion  58 , which is offset from the second shank portion  60  in this case, rotates about the axis  54 . 
         [0018]    As shown in  FIG. 3 , the first shank portion  58  thereby interacts with the lower wear pad  22  and provides a camming action to the wear pad  22 . The camming action and motion of the first shank portion  58  leads to a corresponding motion in the wear pad  22 , thereby allowing for adjustment of the gap  72 . Once the gap  72  is adjusted, the nut  64  may be further tightened to retain the wear pad  22  in this position with gap  70 ,  72  spacing until it is time for another adjustment. Additional adjustments may be made by loosening the nut  64 , rotating the bolt  52  to provide a camming action to move the wear pad  22 , and then retightening the nut  64 . The wear pad assembly  50  may simplify the adjustment of wear pads  22  used to maintain clearance gaps for parts or assemblies mounted to feed guides. 
         [0019]    For example, the wear pad  22  is adjusted in a lateral direction by turning the hex head part  56  of the bolt  52 . In one embodiment, the nut  64  on the wear pad assembly  50  is hand tightened, then the bolt  52  rotated by a wrench, thus moving the wear pad  22  in the lateral direction, in or out, to set a desired gap  72 . 
         [0020]    In another embodiment, wear pad assembly  50  is designed such that the both the lower wear pad  22  and the internal wear plate  24  are adjusted simultaneously. The first shank portion  58  on the bolt  52  is designed to engage and interact with both the lower wear pad  22  and internal wear plate  24  along the second axis  62 . The second shank portion extends through and engages the mounting slide  14 . As the bolt  52  is rotated, the first shank portion  58  rotates about the first axis  54  to provide a camming action to the wear pad and plate  22 ,  24 , thereby repositioning the wear pad and plate with respect to the mounting slide  14  and the feed guide  12 . 
         [0021]    In another embodiment, the first shank portion  58  on the bolt  52  is divided into a lower portion and an upper portion. The lower portion engages and interacts with the lower wear pad  22 , while the upper portion engages and interacts with the internal wear plate  24 . The lower and upper portions may be offset along two axes and therefore provide for a phased motion of the wear pad  22  and plate  24 , for example to adjust one inwardly and the other outwardly at the same time. Alternatively, the lower and upper portions may lie along the same axis, but have different diameters, such that the wear pad  22  and wear plate  24  are adjusted in the same direction, but by differing distances. 
         [0022]      FIGS. 4-5  depict another embodiment of a bushing  100  for use with a wear pad assembly  102  and feed guide  12 . The bushing  100  shown in  FIG. 4  is eccentric with a head  104  and a body  106  extending along a longitudinal axis  108 . The head  104  may be hexagonal for use with a wrench, or have other head shapes as are known in the art. A bore  110  is oriented longitudinally off-axis though the bushing  100 , such that the bore  110  is offset from the longitudinal axis  108  of the bushing  100  to create the eccentricity. The bore  110  may also have a countersink  112  located on the head  104 . 
         [0023]    An example of the eccentric bushing  100  and wear pad assembly  102  in use with a feed guide  12  is shown in  FIG. 5 . The body  106  of the bushing  100  is inserted through apertures in the wear pads  22 ,  24 . A bolt  114  or other fastener is inserted through the bore  110  in the bushing  100  and connected to the mounting side  14 . The head  116  of the bolt  114  fits into the countersink  112  in the bushing  100 . A shim pack  118  and washers  120  may be used to adjust gaps and provide smoother rotation of the wear pads  22 ,  24  during adjustment. A nut  122  or the like is affixed to a threaded end of the bolt  114 . The wear pads  22 ,  24  are adjusted by rotating the head  104  of the bushing  100  with a wrench or other tool corresponding to the shape of the head  104 . The bore  110  through the bushing  100 , and the corresponding bolt  114  through the bore  110 , are offset from the longitudinal axis  108  of the bushing  100 , to act as a cam when the bushing  100  is rotated about the bolt  114 . As the bushing  100  is rotated, the body  106  portion exerts a force and causes the wear pads  22 ,  24  to move with a cam action. When the wear pads  22 ,  24  and corresponding gaps with the feed guide  12  are in a desired position, the nut  122  and bolt  114  may be tightened to retain the wear pads  22 ,  24  in their respective positions until a repositioning of the wear pads  22 ,  24  is desired. 
         [0024]    In an alternate embodiment, the bushing  100  is inserted only through an aperture in the lower wear pad  22  for adjustment of the lower wear pad  22 . The bolt  114  is inserted though the bushing  100 , the internal wear plate, and the mounting slide  14 . Rotation of the bushing  100  thereby adjusts only the lower wear pad  22  with a cam action. 
         [0025]    In another embodiment, the body  106  of the bushing  100  is divided into a lower portion and an upper portion. The lower portion engages and interacts with the lower wear pad  22 , while the upper portion engages and interacts with the internal wear plate  24 . The lower and upper portions may be offset along two axes and therefore provide for a phased motion of the wear pad  22  and plate  24 , for example to adjust one inwardly and the other outwardly at the same time. Alternatively, the lower and upper portions may lie along the same axis, but have different diameters, such that the wear pad  22  and wear plate  24  are adjusted in the same direction, but by differing distances. 
         [0026]    While embodiments of the invention have been illustrated and described, it is not intended that these embodiments illustrate and describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, features of various implementing embodiments may be combined to form further embodiments of the invention.