Abstract:
An automatic screwfeeder is adapted for use with a hand drill. The automatic screwfeeder operates to transfer uncollated screws from a screw holder into a staged position. A driving bit sequentially engages individual fasteners and drives them into a workpiece. The screwfeeder includes a front assembly separable from a rear assembly to allow replacement of the driving bit.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention relates generally to a power screwdriver and, more particularly, to an automatic screwfeeder mechanism for attachment to a conventional hand drill.  
         [0002]     A number of fastener installation tools have been adapted to sequentially install fasteners to a workpiece. Typically, the fasteners are interconnected to one another with a web which is subsequently discarded after the fastener has been installed. Unfortunately, the cost and availability of collated and interconnected fasteners is prohibitive to widespread use of such devices.  
       SUMMARY OF THE INVENTION  
       [0003]     Accordingly, it is an object of the present invention to provide an automatic screwfeeder for use with a conventional hand drill that does not require collated fasteners.  
         [0004]     It is another object of the present invention to provide an automatic screwfeeder including a substantially translucent access cover to allow an operator to view fed fasteners and clear jams should they occur.  
         [0005]     It is another object of the present invention to provide an automatic screwfeeder having a body axially moveable relative to a sliding core where the body includes a camming surface selectively engageable with a toggle. The toggle is adapted to retain fasteners in a pre-staged area and allow individual fasteners to enter a staging area once the previously staged fastener has been driven.  
         [0006]     It is another object of the present invention to provide a fastener engaging device such that an operator must input a predetermined load greater than the weight of the automatic screwfeeder to begin driving a fastener. This feature assures that inadvertent screw feeding and/or driving does not occur.  
         [0007]     It is another object of the present invention to provide an automatic screwfeeder having a front assembly separable from a rear assembly. A driving bit is rotatably supported on the front assembly and may be replaced by disconnecting the front and rear assemblies.  
         [0008]     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:  
         [0010]      FIG. 1  is a fragmentary perspective view of an exemplary hand drill coupled to an automatic screwfeeder of the present invention;  
         [0011]      FIG. 2  is a partial exploded perspective view of a front assembly of the automatic screwfeeder of the present invention;  
         [0012]      FIG. 3  is a fragmentary exploded perspective view of a rear assembly of the automatic screwfeeder of the present invention;  
         [0013]      FIG. 4  is a fragmentary cross-sectional side view of the automatic screwfeeder of the present invention;  
         [0014]      FIG. 5  is a top view of the automatic screwfeeder of the present invention;  
         [0015]      FIG. 6  is a fragmentary perspective view of the front assembly of the automatic screwfeeder of the present invention;  
         [0016]      FIGS. 7-10  are partial cross-sectional side views depicted non-actuated positions of the automatic screwfeeder of the present invention; and  
         [0017]      FIG. 11  is an exploded perspective view of the filter of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0018]     The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.  
         [0019]     Referring to  FIGS. 1-3 , an automatic screwfeeder  10  is shown coupled to an exemplary hand drill  12 . Hand drill  12  is drivingly engageable with screwfeeder  10  to transfer torque to a bit  14 . Screwfeeder  10  is operable to consecutively drive non-collated screws  16  ( FIG. 7 ) into a workpiece such as a floor without requiring the operator to manually feed each fastener to be installed.  
         [0020]     Screwfeeder  10  includes a sliding core  18 , a body  20 , a screw accumulation tube  22 , an extension tube  24 , a drive mechanism  26  and a feeder mechanism  28 . Body  20  and sliding core  18  form a front assembly  30  which is separable from a rear assembly  32 . Rear assembly  32  includes screw accumulation tube  22 , extension tube  24 , and a pair of clamps  34  interconnecting extension tube  24  and screw accumulation tube  22 . A nut  36  is rotatably captured on the end of extension tube  24 . Nut  36  is threadingly engagable with body  20  to couple front assembly  30  to rear assembly  32 . Rear assembly  32  and front assembly  30  are separated from one another to replace bit  14 .  
         [0021]     A driveshaft  37  is rotatably supported within extension tube  24  by a pair of bushing assemblies  38 . Driveshaft  37  includes a hexagonally shaped first end  39  which is selectively engageble by an output member of hand drill  12 . Driveshaft  37  includes a second end  40  which is also hexagonally shaped. Second end  40  is drivingly engaged with a coupling  42 . Coupling  42  drivingly interconnects driveshaft  37  and bit  14 . A handle  44  is coupled to extension tube  24  to assist an operator in applying an axial force to automatic screwfeeder  10  during a screw driving operation.  
         [0022]     Screw accumulation tube  22  includes a first end  45  and a second end  46 . Second end  46  is coupled to sliding core  18  by a grommet  47 . Grommet  47  includes a substantially cylindrical body  48  having an aperture  50  axially extending therethrough. A plurality of ribs  52  radially extend from an outer surface  53  of body  48 . An enlarged head  54  is positioned at one end of grommet  47 . Head  54  defines an annular surface  56  which engages an end face  58  of sliding core  18 . Specifically, sliding core  18  is bifurcated to include a first housing portion  60  spaced apart from a second housing portion  62 . First housing portion  60  defines a screw feed track  64 . Second housing portion  62  defines a portion of a bore  66 . First housing portion  60  includes a plurality of recesses  68  for receipt of ribs  52 . Screw feed track  64  intersects bit bore  66  at nose cavity  70 . Preferably, second end  46  of screw accumulation tube  22  is press fit within grommet  47  to interconnect screw accumulation tube  22  and sliding core  18 .  
         [0023]     A filter  72  is coupled to first end  45  of screw accumulation tube  22 . Filter  72  is a two-part assembly coupled to screw accumulation tube  22  via fasteners  73 . As best shown in  FIG. 11 , filter  72  includes a plurality of ribs  74  including apertures  76  extending therethrough. Apertures  76  are offset from one another to define a serpentine path for screws  16  to follow. This serpentine path functions to greatly increase the difficulty of insertion of a screw head first instead of in the proper direction of tip first. Additionally, ribs  74  resist backflow of screws  16  if an operator should invert screwfeeder  10  to a position where gravity forces the screws toward filter  72 .  
         [0024]     Sliding core  18  is axially movable relative to body  20  between a collapsed position shown in  FIG. 4  and an extended position shown in  FIG. 7 . To accommodate the relative motion of the components, clamps  34  include supports  77  which are coupled to screw accumulation tube  22  in a slip-fit manner. Accordingly, screw accumulation tube  22  axially translates with sliding core  18  and moves relative to extension tube  24  and body  20 .  
         [0025]     A panel  78  is slidably positioned between sliding core  18  and body  20 . Panel  78  translates during movement of sliding core  18  to assure that an additional opening is not formed in front assembly  30  during operation. When sliding core  18  is in the extended position, a lip  79  ( FIG. 7 ) of panel  78  engages an upturned portion of sliding core  18  to properly position panel  78 .  
         [0026]     Body  20  of front assembly  30  includes a first half  80  and a second half  82 . Both first half  80  and second half  82  are preferably constructed as injection molded shells which are substantially similar to one another. First half  80  is coupled to second half  82  via a plurality of screws (not shown). Body  20  is divided into a forward compartment  84  and a rearward compartment  86  by a bulk head  88 . Bulk head  88  includes provisions for retaining certain components of drive mechanism  26 .  
         [0027]     Drive mechanism  26  includes bit  14 , a sleeve  90 , a return spring  92 , a retaining clip  94 , coupling  42  and driveshaft  37 . Return spring  92  circumscribes sleeve  90  and is positioned within forward compartment  86  to bias sliding core  18  away from body  20  toward the extended position. As shown in  FIG. 2 , body  20  includes a plurality of rectangular protrusions  100  selectively engageable with sliding core  18  to limit the travel of body  20  relative to sliding core  18 .  
         [0028]     Sleeve  90  includes a first end  104  having a flange  106  which is retained within slots formed in first half  80  and second half  82 . A second end  108  of sleeve  90  and a portion of return spring  92  are slidingly supported by sliding core  18 .  
         [0029]     Bit  14  includes a first end  110  and a second end  112 . First end  110  includes a tip  114  selectively engageable with the head of the fastener  16 . Second end  112  includes a hexagonal section  116  which is drivingly coupled to driveshaft  37  positioned within extension tube  24 . Bit  14  is positioned within sleeve  90  and retained therein by retaining clip  94 . Driveshaft  37  provides torque to bit  14  via coupling  42 . Retaining clip  94  restrains bit  14  from axially moving relative to sleeve  90  but allows rotational movement relative thereto. Based on the interconnections previously described, it should be appreciated that sleeve  90  and bit  14  axially translate with body  20  during operation.  
         [0030]     As best shown in  FIGS. 4 and 7 , a detent spring  117  includes an arm portion  118  and an upset portion  120 . Arm portion  118  is cantilever mounted to body  20 . Detent spring  117  functions to require an operator of automatic screwfeeder  10  to purposely input a force greater than the weight of the screwfeeder to move body  20  and sliding core  18  toward the collapsed position. Incorporation of detent spring  117  assures that inadvertent driving or displacement of a screw positioned in a staged position  122  does not occur. To accomplish this goal, upset portion  120  is positioned within the path of an outer wall  124  of sliding core  18 . As the external force is applied, outer wall  124  engages upset portion  120  and forces arm portion  118  to deflect thereby allowing sliding core  18  to collapse within body  20 .  
         [0031]      FIGS. 5 and 6  depict a depth stop  125  to include a series of annular stepped surfaces  126  which are selectably engagable with a portion of sliding core  18 . Depth stop  125  includes a lever  128  protruding through an aperture  130  formed in body  20 . Depth stop  125  is axially retained within body  20 , but is free to rotate the arcuate distance defined by aperture  130 . By rotating depth stop  125 , stepped surfaces  126  rotate into and out of position for engagement with sliding core  18 . Therefore, the travel of body  20  relative to sliding core  18  is limited by the position of depth stop  125 . By limiting the travel of body  20  relative to sliding core  18 , the fully extended position of bit  14  is defined. It is contemplated that the full range of adjustment varies ⅛″. For example, a screw head may be counter-sunk {fraction (1/16)}″ below a surface of the workpiece or may be positioned ⅛″ below the plane of the work surface.  
         [0032]     Sliding core  18  includes a first side  132  coupled to a second side  134  by a plurality of fasteners (not shown). Each of first and second sides  132  and  134  are preferably injection molded components in the shape of thin walled shells. As previously mentioned, sliding core  18  includes screw feed track  64  and bit bore  66 . A toggle  140  of feeder mechanism  28  is biased toward the position depicted in  FIG. 7  by a torsional spring  142 . Toggle  140  is rotatable about a pin  144 . Toggle  140  includes a first corner  146 , a second corner  148  and a leg  150 . First corner  146  and second corner  148  are in communication with screw feed track  64 . Toggle  140  functions to selectively allow the threaded fasteners to enter staged position  122  where the screw  16  is coaxially aligned with the axis of rotation of bit  14 . A magnet assembly  152  is positioned within a pocket formed within sliding core  18  to attract the head of screw  16  and retain the screw in staged position  122 . Magnet assembly  152  includes a magnet  153  and a ferromagnetic cup  154 .  
         [0033]     Sliding core  18  includes a window  155  to provide access to staged position  122  and a portion of screw feed track  64 . A translucent access cover  156  is pivotally coupled to sliding core  18  to selectively close window  155 . Each side  132  and  134  of sliding core  18  includes a socket  158  for receipt of a trunion  160  extending from access cover  156 . Sliding core  18  includes a groove  162  aligned with a recess  164  formed in access cover  156 . An elastic band  166  is selectively disposed within groove  162  and recess  164  to retain access cover  156  in a closed position. If an operator desires access to staged position  122  or screw feed track  64 , elastic band  166  is partially or completely detached to allow opening of access cover  156 .  
         [0034]      FIGS. 7-10  depict screwfeeder  10  at various positions during the process of driving screw  16  into a workpiece. Specifically,  FIG. 7  depicts body  20  and sliding core  18  in a fully extended position. An exemplary screw  16   a  is shown located within screw accumulation tube  22  at a pre-staged position. In the pre-staged position, the head of screw  16   a  is engaged by second corner  148  of toggle  140 . It should be appreciated that leg  150  of toggle  140  is clear of an outer surface  168  and an upper cam surface  170  of body  20  at this time. Torsional spring  142  biases toggle  140  in a counter-clockwise direction and loads a detent  172  of toggle  140  against a seat  174  of sliding core  18 .  
         [0035]     With reference to  FIG. 8 , sliding core  18  and body  20  are located in the fully collapsed position. The extent to which core  18  is allowed to telescope within body  20  is limited by depth stop  125 . One of annular stepped surfaces  126  contacts an end face  172  of sliding core  18  at the fully collapsed position. At this time, bit  14  is fully extended and tip  114  protrudes from sliding core  18  and body  20 . During relative movement of sliding core  18  and body  20 , upper cam surface  170  engages leg  150  to rotate toggle  140  in a clockwise direction. Because the screws are being acted upon by gravity, screw  16   a  disengages second corner  148  and drops into engagement with first corner  146 . The tip of a subsequent screw  16   b  engages the head of screw  16   a.    
         [0036]      FIG. 9  depicts housing  20  and sliding core  18  moving from the collapsed position toward the extended position. During this movement, leg  150  disengages upper cam surface  170 . Accordingly, toggle  140  rotates counter-clockwise to release screw  16   a  and capture screw  16   b . Under the pull of magnet  152 , the tip of screw  16   a  rides against sleeve  90  until it is retracted within bit bore  66 .  
         [0037]      FIG. 10  shows sliding core  18  and body  20  positioned in the fully extended position. Sleeve  90  and return spring  92  are now clear of staged position  122 . Therefore, magnet assembly  152  attracts screw  16   a  and orients it within bit bore  66 . Screw  16   a  is now located within the staged position  122  where the screw&#39;s longitudinal axis is generally aligned with the rotational axis of bit  14 . When an operator applies sufficient force to handle  44  and/or hand drill  12  to overcome detent spring  117 , bit  14  engages screw  16   a  to simultaneously rotate and axially translate screw  16   a  into the workpiece. With a quantity of screws in the screw accumulation tube  22 , the screw feeding and driving process may be rapidly repeated without requiring the operator to individually handle the screws or bend over from an upright or near-upright standing position.  
         [0038]     Furthermore, the foregoing discussion discloses and describes merely exemplary embodiments of the present invention. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims, that various changes, modifications and variations may be made therein without department from the spirit and scope of the invention as defined in the following claims.