Abstract:
A fastener puller capable of removing fasteners embedded in a material having a surface, the puller having a handle, a horn having a wedge, connecting means form mounting the horn to the handle and an elongated ram slidably mounted with respect to the handle. As the ram is moved along a slide path, the ram abuts the horn causing the wedge to be forced underneath the head of a fastener. As the ram continues along the slide path and contacts the surface, the horn and handle are pushed away from the surface causing the fastener to be pulled out of the material.

Description:
FIELD OF THE INVENTION 
     This invention relates to an apparatus for pulling fasteners and more particularly to hand tools for pulling upholstery staples and nails. 
     BACKGROUND OF THE INVENTION 
     Fasteners, such as staples and nails, that have been embedded in wood are used in a wide variety of applications. Fore example, fabric is often affixed to the wooden frames of upholstered furniture using upholstery staples. Upholstery staples have elongated points so as to be embedded deep into a wood frame. Upholstery staples are embedded deep into a wooden frame so as to maintain the fabric in place for a long time. 
     When reupholstering furniture however, it is often very difficult to remove the staples so as to place new fabric on the frame because the staples are embedded very deep into the wood. Generally, the staples are removed by pliers, flat screwdrivers and awls. These tools can make the staple removal process very time-consuming. In fact, it can take nearly one hour for one person to remove the staples from a standard wing chair. In many situations, the staples are left in the frame and a new staple is embedded in the frame at a different location for the new fabric. This latter option is considered to be poor upholstery practice. 
     Two hand tools have been developed to assist in this process. In U.S. Pat. No. 4,245,817 to Peoples a pneumatic staple puller was proposed. This used two claw members to pierce underneath the crown of the staple and to lift the staple from the wood. U.S. Pat. No. 4,637,538 to Wagner proposed a hand-held tool which is used to drive a wedge underneath the crown of the staple from the side. The Peoples staple puller requires great precision and the ends of the claw members are likely to break after repeated removals. The Wagner staple puller suffers from a disadvantage that it is applied at an angle to the surface in which the staple is embedded. As a result, there will be situations where there will not be room for the main housing of the staple puller because the frame of the furniture will be in the way. As well, the chisel-shaped end portion of the puller must be manually lodged underneath the crown of the staple before the device is activated. This may not be possible when the staple is deeply embedded in the material. 
     As well, it is also difficult to remove nails embedded in wood. Generally, the claw of a hammer is used to pull a nail from wood. However, if the head of the nail is below the surface of the wood, it is difficult to position the claw underneath the head of the nail. 
     Accordingly, there is a need for a pneumatically powered fastener puller which is fast, easy to use and may be applied perpendicular to the surface in which the fastener is embedded. 
     SUMMARY OF THE INVENTION 
     The present invention is accordingly directed to a fastener puller for removing a fastener such as a staple or a nail embedded in a material having a surface. 
     The subject fastener puller has a handle and connecting means fixedly attached to the handle for connecting a horn to the handle. The horn is mounted on the connecting means and has an elongated stem with an end and a wedge at the end of the stem. The wedge is adapted to fit underneath the head of a fastener. The horn is mounted so that it is moveable relative to the handle from a disengaged horn position to an engaged horn position. An elongated ram is slidably mounted with respect to the handle for longitudinally slidable movement along a slide path from a first ram position through a second ram position to a third ram position. The horn is positioned relative to the ram so that when the ram moves from the first position to the second position, the ram abuts the horn and causes the horn to move from the disengaged position to the engaged position. The ram is positioned so that when the ram moves from the second position to the third position, the ram is in continuous contact with the surface. 
     The fastener puller may also comprise pneumatic or electrical means for moving the ram along the slide path. 
     The fastener puller may also have a guide rod fixedly mounted with respect to the handle. The guide rod has a slot adapted to fit about the head of an embedded fastener. 
     The horn of the fastener puller may be biased to the disengaged position by a biasing member to the disengaged position. 
     In another aspect of the invention, the staple puller may have an adjusting member for adjusting the position of the horn with respect to the guide rod. 
     In an alternative embodiment to the invention, the staple puller may have a ram handle with an elongated ram fixedly mounted on the ram handle. A pull member is slidably mounted with respect to the ram handle and a horn is pivotally mounted to the pull member. The horn has an elongated stem and a wedge at the end of the stem. The wedge of the horn is adapted to fit underneath the crown of the staple. The horn is pivotable from a first horn angle relative to the ram to a second horn angle. The horn is positioned so that when the ram is pushed towards the surface, the ram abuts the horn and moves the horn from the first horn angle to the second horn angle. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will now be described, by way of example only, with reference to the following drawings in which: 
     FIG. 1 is a front view of a staple puller in accordance with a preferred embodiment of the present invention with the trigger removed; 
     FIG. 1A is a bottom view of the base of a component part of the staple puller of FIG. 1; 
     FIG. 2 is a partial sectional side view of the staple puller of FIG. 1; 
     FIG. 3 is a side view of the component of FIG. 2 prior to operation; 
     FIG. 4 is a side view of the component of FIG. 3 in a second position; 
     FIG. 5 is a side view of the component of FIG. 3 in a third position; 
     FIG. 6 is a side view of an alternative preferred embodiment of a tool extension in accordance with an aspect of the present invention; 
     FIG. 7 is a front view of a further alternative embodiment of the present invention; 
     FIG. 8 is a partial sectional front view of a further alternative embodiment of the present invention; 
     FIG. 9 is a partial sectional side view of the embodiment shown in FIG. 8 in the first position; 
     FIG. 10 is a partial sectional side view of the embodiment shown in FIG. 8 in the second position; 
     FIG. 11 is a partial sectional side view of the embodiment shown in FIG. 8 in the third position; 
     FIG. 12 is a side view of an alternative preferred embodiment of a tool extension in accordance with an aspect of the present invention; 
     FIG. 13 is a bottom view of the horn of the embodiment shown in FIG. 12; 
     FIG. 14 is a side view of the lower portion of another embodiment of the horn; 
     FIG. 15 is a bottom view of an alternative embodiment of the horn for use in a nail puller. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIGS. 1 and 2, illustrated therein is a pneumatic fastener puller  20  made in accordance with a preferred embodiment of the present invention. Except where otherwise stated, fastener puller  20  will be described as a staple puller. Pneumatic staple puller  20  includes an air inlet port  22 , a housing  24 , a trigger  26 , and a tool extension  28 . Staple puller  20  may be connected to a source of pressurized air via air inlet port  22 . 
     In this application, the perpendicular direction is generally indicated by tool extension  28  with a material  72  defining the bottom of FIG.  2 . 
     Housing  24  is composed of handle  30  and cylinder housing  32 . An air flow path extends from air inlet port  22  through handle  30  to a cylinder  33  positioned within cylinder housing  32 . Trigger  26 , when depressed, allows pressurized air to flow from air inlet port  22  through housing  24  and into cylinder  33 . A piston  35  is positioned within cylinder  33  and is forced towards the lower end of cylinder  33  as the pressurized air enters cylinder  33 . 
     Tool extension  28  comprises a ram  34 , U-bracket  36 , pillow bushing  38 , horn  40  and plunge rod  42 . 
     Plunge rod  42  is affixed to the bottom of cylinder housing  32  by means of U-bracket  36 . Plunge rod  42  is composed of an upper rod  44  and a guide rod  46 . The upper end of upper rod  44  is affixed to U-bracket  36  by bolts (not shown). Plunge rod  42  extends downwardly from cylinder housing  32 . The bottom end of guide rod  46  is shaped to fit around a head or crown  50  of a staple  52  while allowing the base of horn  40  to pass underneath crown  50 . FIG. 1A shows a sample cross-section of the bottom end of guide rod  46  adjacent to the four comers of crown  50 . It will be appreciated that other configurations for the bottom end of guide rod  46  can be used so long as lateral motion of the crown  50  of staple  52  relative to the guide rod may be prevented. 
     Ram  34  is composed of a ram stem  54  and a ram base  55 . Ram stem  54  is an elongated member extending into cylinder housing  32  and is affixed to piston  35  therein. Ram base  55  is shaped to surround plunge rod  42  in a channel therein, as shown in FIG.  1 A. 
     Horn  40  comprises a horn stem  56  and a horn wedge  58 . Horn  40  is mounted on pillow bushing  38 . Pillow bushing  38  is mounted between plunge rod  42  and ram  34  by means of a horn pin  62  passing through plunge rod  42  and pillow bushing  38 . Pillow bushing  38  is provided with a groove  64  into which a horn mount  66  protrudes. Groove  64  lies adjacent to plunge rod  42  and is sized to fit the width of horn stem  56  when horn  40  is parallel to plunge rod  42 . Guide rod  46  is provided with a horn channel  65  into which horn stem  56  will fit when in the vertical position. 
     The upper end of horn stem  58  is provided with an indentation  70 . Horn mount  66  fits within indentation  70  such that horn  40  pivots about horn mount  66 . A biasing member such as a leaf spring  68  is mounted between pillow bushing  38  and plunge rod  42  and is affixed at its end to approximately the midpoint of horn stem  56 . Leaf spring  68  biases horn wedge  58  at a first angle away from guide rod  46  to a disengaged position. 
     Horn  40  is mounted such that horn wedge  58  is positioned to fit underneath the crown  50  of a staple  52  located within guide rod  46  when horn  40  is pivoted towards plunge rod  42 . 
     In operation, the lower end of guide rod  46  is placed over the crown  50  of staple  52  embedded in a material  72 . Staple puller  20  is oriented as shown in FIG. 2 with handle  30  generally parallel to a surface  74  of material  72  and cylinder housing  32  generally perpendicular to surface  74 . Air inlet port  22  is connected to a pressurized air source. As shown in FIGS. 2 and 3, ram  34  is placed in a first ram position within cylinder housing  32  such that horn wedge  58  is allowed to assume its disengaged position away from the central axis of plunge rod  42 . When trigger  26  is depressed, highly pressurized air is permitted to enter air inlet port  22  and passes into cylinder  33 . The pressure of the air feeding cylinder  33  forces piston  35  and ram  34  which is attached thereto downwards. Ram  34  in its downward motion from its first ram position to a second ram position as shown in FIG. 4, frictionally engages horn stem  56  forcing horn wedge  58  towards the staple  52  located at the bottom of guide rod  46 . As ram  34  descends rapidly to the second ram position, horn  40  is pivotally forced from the disengaged position to the engaged position and horn wedge  58  is forced underneath crown  50  of staple  52  lifting it upwards along the wedge. Horn wedge  58  is received within the base of guide rod  46 . Horn stem  56  is also received in horn channel  65 . Crown  50  of staple  52  is held in place between guide rod  46  and horn wedge  58 . At the second ram position, ram  34  is in contact with surface  74 . As air continues to flow into cylinder  33 , ram  34  is forced downwards to a third ram position as shown in FIG.  5 . As ram  34  is forced against the surface  74  of material  72 , housing  24  of pneumatic staple puller  20  is forced upwards away from material  72 . As housing  24  is pushed upwards, horn  40  and plunge rod  42  are also pushed away from the surface. As horn wedge  58  is underneath crown  50  of staple  52 , staple  52  is pulled out of material  72 . 
     It will be appreciated that numerous variants of the above invention may be made. FIG. 6 shows an alternative embodiment of the present invention with a different configuration of the horn. In this embodiment, horn  80  is a prestressed metallic member bent away from plunge rod  42 . Essentially, horn  80  acts as a leaf spring. Horn pin  62  affixes pillow bushing  81  and horn  80  to plunge rod  42 . As ram  34  moves towards surface  74 , horn  80  is pushed inwards towards plunge rod  42  so that horn wedge  58  passes underneath crown  50  of staple  52 . 
     The invention is not limited solely to pneumatically-powered devices. In one variant of the present invention shown in FIG. 7, ram  34  is affixed to a core  37  within a cylindrical solenoid  39 . A trigger (not shown) causes a current to pass through the solenoid  39 , resulting in a magnetic force driving core  37  and ram  34  downwards. The downward force applied to the ram  34  within the solenoid  39  decreases as core  37  nears the bottom of solenoid  39  and there may be insufficient power to drive ram  34  onto the material and push the staple puller upwards to remove the staple. This drawback may be overcome by increasing the power of the solenoid, but this may cause too great an initial downwards force applied to the ram, potentially causing damage to the surface of the material or causing the horn to shear the crown off the staple. A pneumatically powered staple puller will allow for a more constant force. As well, a pneumatically powered staple puller lends itself well to the upholstery industry as many upholstery tools such as staple guns are pneumatically powered. 
     An optional feature for adjusting the height of the horn is shown in FIGS. 1-5. Tool extension  28  is provided with a circular adjustment member  90  adjacent to plunge rod  42  and affixed to horn pin  62 . Horn pin  62  is an eccentric pin. When adjustment member  90  is rotated, the rotation of eccentric horn pin  62  causes pillow bushing  38  to move up and down thus adjusting the height of horn wedge  58  relative to the base of guide rod  46 . Therefore, if staple  52  is deeply embedded in material  72 , adjustment member  90  can be rotated so that horn wedge  58  is lower than the base of guide rod  46 . When ram  34  is driven down, horn wedge  58  will be driven slightly below surface  74  of material  72  so that it passes below crown  50  of staple  52 . 
     A further alternative embodiment of a staple puller  100  is shown in FIGS. 8 to  11 . Staple puller  100  comprises a plunge member  102  and a pull member  104 . Plunge member  102  is capable of slidable vertical movement with respect to pull member  104 . 
     Plunge member  102  is composed of handle  106 , bushing  108  and ram  110 . Handle  106  is provided with a central cavity  112  and a cylindrical cavity  114  passing downwards through the base of handle  106 . Cylindrical cavity  114  is defined at its top by the cylindrical bushing  108  at its bottom by the cylindrical ram  110 . The diameter of bushing  108  is less than the diameter of ram  110 . 
     Pull member  104  is composed of a finger grip  116 , a plunge rod  118 , a horn  120  mounted on a horn pin  122 , a return spring  124  and a leaf spring  126 . Finger grip  116  is generally coplanar with handle  106  and is positioned within central cavity  112 . Plunge rod  118  is generally cylindrical in shape with a slotted or grooved base designed to receive a horn wedge  128  and a crown  130  of a staple  132 . Plunge rod  118  is affixed to the base of finger grip  116  and extends through cylindrical cavity  114  within cylindrical bushing  108  and ram  110 . Horn pin  122  is mounted near the midpoint of the portion of the plunge rod  118  which extends below handle  106 . Leaf spring  126  is mounted to plunge rod  118  and abuts horn  120  such that horn wedge  128  pivots away from the base of plunge rod  118 . 
     The base of return spring  124  is affixed to the outer surface of plunge rod  118  above horn pin  122  such that a portion of plunge rod  118  passes through the centre of return spring  124 . The top of return spring  124  abuts the base of cylindrical bushing  108 . Optionally, return spring  124  is affixed to the base of cylindrical bushing  108 . Return spring  124  is sized such that when it is in its resting position (i.e. not compressed or stretched), the base of finger grip  116  abuts the top of cylindrical bushing  108 . 
     In use, the user grasps handle  106  and positions the staple puller  100  such that the base of plunge rod  118  is placed about the crown  130  of staple  132  which is embedded in material  134  as shown in FIG.  8 . The user then pushes downwards firmly such that ram  110  slides over plunge rod  118  and forces horn  120  inwards until the base of ram  110  is flush with a top surface  134  of material  132  as shown in FIG.  9 . Horn wedge  128  passes underneath the crown  130  of staple  132  pulling the staple slightly out from material  134 . Because plunge member  102  is pushed downwards with respect to pull member  104 , return spring  124  is compressed. 
     At this stage the user maintains a downwards force on handle  106  but releases some of their fingers to grasp finger grip  116 . The user pulls finger grip  106  upwards as seen in FIG.  10 . As a result, staple  132  which is grasped between horn wedge  128  and the base of plunge rod  118  is pulled out of material  134 . The user may then release the downwards force on handle  106 , allowing the force of return spring  124  to direct pull member  104  to its resting position. 
     FIG. 12 shows a further alternative embodiment of the present invention. In this embodiment, a dual-wedge structure is used to remove the staple. Horn  140  is comprised of two stems  154 , 156  having inwardly facing horn wedges  142 ,  143  respectively. Horn  140  is bent at its midpoint and mounted to guide rod  144  by horn pin  146 . Ram  148  is a rectangular body which completely surrounds guide rod  144  and horn  140  when lowered. When ram  148  is driven downwards, horn wedges are driven inwards towards staple  52  and are embedded under crown  50 . Horn wedges  142 ,  143  are designed such that they pass by one another as they are driven beneath crown  50 . An example configuration of horn wedges  142 ,  143  is shown in FIG.  13 . In this configuration, horn wedge  142  is composed of two protruding wedge portions  150  along the sides of wedge  142  while horn wedge  143  has a protruding central wedge portion  152 . Wedge portion  152  is shaped to fit between wedge portions  150  as shown in FIG.  13 . Other configurations will be obvious to those skilled in the art. As with the other embodiments, as ram  148  continues its downwards motion, guide rod  144  moves upwards and pulls staple  52  out of material  72 . 
     FIG. 14 shows an alternative embodiment of the horn used in the various staple pullers described herein. Horn  160  has a stem  162  with a wedge  164  as previously described. Wedge  164  has a top surface  168 . Top surface  168  is provided with an indentation or notch  166  extending across the width of the wedge for receiving the crown of the staple. As wedge  164  is driven underneath the crown of the staple, the crown slides upwards along top surface  168 . When the crown of the staple passes over notch  166 , the crown is caught and maintained in the notch. Any downward sliding of the crown is thus prevented. This version of the horn allows the staple to be stabilized in one position along wedge  164  when the staple is pulled out of the material. This is advantageous as the staple will tend to slide down top surface  68  of wedge  164  as the staple is pulled out if the material. Otherwise, the staple may press against the guide rod as it is removed, potentially causing the staple puller to jam. It is to be understood that various notch configurations can be used as is known to those skilled in the art. 
     FIG. 15 shows a further alternative embodiment of the lower end of the horn for use in a powered nail puller. Wedge  182  of horn  180  is provided with a V-shaped notch  184  and wedge protrusions  186 . As the ram forces the horn to a perpendicular position with respect to the surface, the wedge protrusions  186  pass underneath the head of the nail, lifting it out of the surface as the head slides up the wedge. The shank of the nail fits within notch  184  and horn  180  is positioned so that the movement of wedge  182  towards the nail does not shear off the head of the nail. As the ram abuts the surface, forcing the handle away from the surface, the nail will be pulled from the material. Depending on the length of the nail, the nail may be completely pulled from the material. If it is desired to pull longer nails from the material, a nail puller having a longer ram and a corresponding longer cylinder may be used. It will be obvious to those skilled in the art that other wedge configurations are possible for use in nail pullers. 
     It is to be understood that a wide variety of cross-sectional shapes of rams and guide rods are available to be used in any of the embodiments described. 
     It is to be understood that what has been described are preferred embodiments to the invention. The invention nonetheless is susceptible to certain changes and alternative embodiments fully comprehended by the spirit of the invention as described above, and the scope of the claims set out below.