Patent Publication Number: US-2005127130-A1

Title: Frame tool and fastener

Description:
BACKGROUND OF THE INVENTION  
      This invention relates to tools used for assembling picture frames, and more particularly to such a tool which drives small nails, tabs or pins into a picture frame for holding the glass, the picture, and a backing in place.  
      Pin driver devices are well known in the art and typically use a pneumatic force to drive a nail or a pin (a planar pointed fastener) straight into a wooden frame portion of a picture frame to hold the glass, picture and backing into place. A disadvantage of this type of tool is that the nails or pins often provide insufficient holding power and additional clamping is needed. This additional clamping is generally achieved by bending the driven pins into the backing, an operation which typically requires an additional step.  
      Therefore, it is desired to have a device that combines a driving mechanism with a bending apparatus to both drive a pin into the wooden frame and subsequently bend it for additional clamping. Prior attempts to solve this problem employ a dual pneumatic piston assembly that separately drives a driver blade with one pneumatic piston for driving the pin and subsequently bends the pin with a separate mechanism using a second pneumatic piston. This operation is mechanically burdensome and, among other things, requires an extra connection for the second air piston. Operators of such frame tools favor an inexpensive and durable product that is simple to maintain. The above-identified combined two-step mechanism for driving and bending a pin has resulted in bulkier and more complicated devices.  
      Another design factor of frame pin drivers is that the pin driving mechanism be removable from the tool structure for maintenance purposes. Still another design factor is that the pin driver assembly be interchangeable with an assembly which does not bend the fastener.  
      Thus, there is a need for a frame tool capable of bending a pin when in the driven position that is mechanically inexpensive and is convenient to use. Furthermore, there is a need for such a device where the driving mechanism is easily removed for maintenance or interchangeable assembly purposes.  
     BRIEF SUMMARY OF THE INVENTION  
      The above-identified needs are addressed by the present frame tool with a pin driver for driving pins into a frame element. One feature of the present tool is a hammer arm assembly that is actuated when the driver blade moves from a retracted position to an extended position so that the pin is driven into a frame element, then bent for additional clamping. In the preferred embodiment, the hammer arm assembly is pivotally actuated by the driver blade. A guide shoe is also included in the present pin driver to guide the pins from a ready position to a driven position and is removable from the tool to allow access to the hammer arm assembly. Furthermore, a biasing force is exerted on the hammer arm assembly toward a first position such that after bending a pin, the hammer arm assembly is positioned to be ready for a next pin. An optional feature of the present pin driver is a bumper pad that is configured to absorb impact energy generated by the hammer arm assembly striking the pin for protecting the guide shoe and/or the hammer arm assembly.  
      More specifically, a pin driver usable with a frame tool is provided that includes a reciprocating driver blade moveable between a retracted position and an extended position. A guide shoe is associated with the driver blade for guiding the pin from a ready position to a driven position. A hammer arm assembly is also mounted in an operational relationship to the guide shoe and is configured to strike and bend the pin upon reaching the driven position.  
      In an additional embodiment, a frame tool with a pin driver for driving pins into a frame element includes a housing. The frame tool further includes a reciprocating driver blade moveable relative to the housing between a retracted position and an extended position. A hammer arm assembly is mounted in operational relationship to the guide shoe and is configured to strike and bend the pin upon reaching the driven position. The driver blade is configured to be pivotally associated with the hammer arm assembly such that the movement of the driver blade from the retracted position to the extended position causes the hammer arm assembly to move from a first position to a second position at which the pin is bent. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a fragmentary side elevational view of a tool suitable for incorporating the present invention;  
       FIG. 2  is a fragmentary front view of the tool shown in  FIG. 1 ; and  
       FIG. 3  is a cross section taken along the line of  3 - 3  of  FIG. 2  and in the direction generally indicated. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      Referring now to  FIGS. 1, 2  and  3 , a frame tool for driving pins into a frame element is generally designated  10 . Included on the preferably pneumatic frame tool  10  is an air intake connection (not shown) that connects to a gas or supply air line (not shown). Electronic or combustion powered tools are also contemplated. In the preferred embodiment, a handle  14  connects a housing  16  for enclosing a cylinder  18  as shown in  FIG. 3  to the air intake connection. Compressed air from the gas supply is released into the cylinder  18  by a trigger mechanism  20 . As known in the art, the cylinder  18  houses a pneumatic piston  22  that moves down the cylinder to an extended position shown in  FIGS. 2 and 3  when the compressed air enters the cylinder  18 . A check valve  24  allows air to flow into an outer chamber  26  for eventual reentry into the cylinder  18  through ports  28  for returning the piston to the start or ready position.  
      Referring now to  FIGS. 2 and 3 , a pin driver, generally designated  30  and usable with the frame tool  10 , includes a reciprocating driver blade  32  moveable to the extended position. The driver blade  32  is attached to the pneumatic piston  22  for common movement, preferably by a clevis screw  33 . In the preferred embodiment, the driver blade  32  is secured to the clevis screw  33  by at least one driver blade fastening pin  34 . The cylinder  18  further includes a driver blade seal  36  configured to prevent air from escaping from the housing  16  past the cylinder. The driver blade seal  36  is preferably made of resilient material such as rubber or the equivalent and contains a slit  38  through a middle portion for slidingly allowing the driver blade  32  to pass while preventing the escape of air from the cylinder  18 . A preferably annular seal spacer  40  is provided for supporting the driver blade seal  36  and is preferably made of metal or equivalent material to provide the required rigidity.  
      Now referring to  FIGS. 1, 2  and  3 , a guide shoe  42  is associated with the driver blade  32  for guiding a pin  44  to a driven position ( FIGS. 2 and 3 ). The guide shoe  42  is preferably configured to be tapered towards a tip  46  (when viewed from the front ( FIG. 2 )) such that a location of the pin  44  in the driven position is generally predeterminable while the pin is ready to be driven. It is also preferred that the guide shoe  42  is wedge-shaped when viewed from the side ( FIGS. 1 and 3 ) to facilitate insertion and driving of the pin  44  into the frame at an acute angle ∝. It is desirable that the pin  44 , upon being driven, exerts a clamping force against a backing  48 , a picture  50 , and a glass  52  as shown in  FIGS. 1 and 3  to retain these components against a base  54  of a preferably wood frame  56 . It is contemplated, however, that the pin driver  30  is usable for frames made of other materials as well as other objects besides frames.  
      The pin driver  30  further includes a hammer arm assembly  58  mounted in operational relationship to the guide shoe  42  and configured to strike and bend the pin  44  upon reaching the driven position. The hammer arm assembly  58  is provided with a hammer arm  59  made of metal or equivalent material, and is preferably attached to a shaft end  60  of a shaft  61  mounted on the guide shoe  42  in transverse relationship to the driver blade  32 .  
      The driver blade  32  is configured to be associated with the hammer arm assembly  58  such that the movement of the driver blade to the extended position causes the hammer arm assembly to pivotally move from a first or retracted position (shown in phantom in  FIG. 3 ) to a second or impact position at which a portion of the pin  44  projecting above the base  54  is bent at an angle against the backing  48  ( FIG. 3 ). The hammer arm  59  extends generally parallel to the driver blade  32  when viewed from the side ( FIG. 3 ). An elongated portion  62  of the arm  59  is preferably configured to have a taper generally corresponding to the tapered guide shoe tip  46 . In the preferred embodiment, the elongated portion  62  slants to an obtuse angle β ( FIG. 2 ) located below a pin magazine  63  ( FIG. 1 ). The obtuse angle β is configured to position a lower segment  64  of the elongated portion  62  in alignment with the driver blade  32 .  
      The lower segment  64  of the arm  59  is provided with, a striking tip  65  that extends outward towards the pin  44  in the driven position. It is preferred that the striking tip  65  resides at an approximate 95 degree angle from the lower segment  64 , however, any angle within the general 90 degree position that is capable of bending the pin is also contemplated. It is also preferred that the striking tip  65  be a metal extension of the hammer arm  59 , however, other striking tips such as threaded fasteners and extension attachments are also contemplated.  
      Now referring to  FIGS. 2 and 3 , the shaft  61  is associated with the guide shoe  42  and is configured for compelling a pivoting action of the hammer arm assembly  58 . In the preferred embodiment, the shaft  61  is cylindrical and the guide shoe  42  is provided with pivot eyelets  66  configured to rotatably receive the shaft. The pivot eyelets  66  are linearly spaced apart and are positioned on an upper portion  67  of the guide shoe  42  opposite from the tip  46 . At least one blade striker arm  68  is coupled to the shaft  61  by a fastening pin  69  ( FIG. 3 ) or other known fastening techniques so that a free end  70  of the striker arm  68  projects generally normally to the direction of travel of the driver blade  32 .  
      Now referring to  FIG. 2 , the driver blade  32 , which reciprocates within a slot in the guide shoe  42 , has at least one shoulder  71  located closer to a rear end  72  than to a tip end  74 . It is preferred that the at least one shoulder  71  is represented by a protrusion of the driver blade  32 , resulting in the tip end being narrower than the rear end  72 . Each shoulder  71  is associated with a corresponding at least one blade striker arm  68  such that the shoulder abuts the corresponding blade striker arm when the driver blade  32  moves to the extended position. In the preferred embodiment, two blade striker arms  68  are provided upon the shaft  61 , one on each side of the driver blade  32 .  
      The blade striker arms  68  move in an arc A ( FIG. 3 ) caused by the driver blade  32  and have a movement ratio with the hammer arm assembly  58  of approximately 1:5 such that a 1 millimeter displacement of the free end  70  of the at least one blade striker arms result in a general 5 millimeter displacement of the lower segment  64  of the hammer arm assembly. It is also preferred that the movement of the hammer arm  59  due to the driver blade  32  striking the blade striker arms is approximately 0.060 inches between the first and second positions ( FIG. 3 ). It is contemplated that the amount of displacement may vary to suit the application.  
      Referring now to  FIG. 3 , the pin driver  30  is also configured for exerting a biasing force on the hammer arm assembly  58  to urge the hammer arm assembly to the first position. It is preferred that at least one spring  80  is provided for exerting the biasing force. One end of the spring  80  is positioned in a recess  82  on the striker arm  68  and an opposite end of the spring is positioned in a guide shoe recess  84  in the guide shoe  42 . In this construction, the spring  80  will force the hammer arm assembly  58  to rotate back to the first position after bending the pin  44 . In the preferred embodiment, one spring  80  is provided for each of the preferably two blade striker arms  68 .  
      Referring now to  FIGS. 1 and 2 , the pin magazine  63  positioned on the frame tool  10  is configured to feed pins  44  to the pin driver  30 . A guide plate  90  is positioned between the guide shoe  42  and the pin magazine  63 . The guide plate  90  is generally flat and contains a broadened portion  92  situated on a piston side  93  and a guide plate tip  94  tapered to conform with the guide shoe  42 . In the preferred embodiment, the guide plate  90  is also configured to have a pin receiving hole  96  on the broadened portion  92  of the guide plate  90  such that pins  44  may be fed from the magazine  63  into the ready position for impact by the driver blade  32 . Preferably, edge margins of the hole  96  are chamfered to facilitate pin guiding.  
      It is also preferred that the guide plate  90  is provided with at least two screw holes  98  located on adjacent sides of the pin receiving hole  96 . The guide plate  90  is secured by fasteners  100  such as screws passing through the holes  98  and fastened to the frame tool  10 . The fasteners  100  are configured to be removable such that the guide shoe  42 , the guide plate  90 , and the rest of the pin driven  30  are detachable from the frame tool  10 . Removing the guide shoe  42  from the frame tool  10  provides the user with visual and physical access to the driver blade  32  and the hammer arm assembly  58  for maintenance purposes of the pin driver  30 . Such removal of the pin driver  30  allows the attachment to the tool of an alternative assembly which does not bend the fastener.  
      Additionally, the guide plate  90  is constructed and arranged such that the striking tip  65  of the hammer arm  59  strikes the pin  44  upon reaching the driven position. The guide plate  90  is provided with an opening  102  disposed to allow the striking tip  65  to strike the pin  44 , however, other configurations of guide plate are contemplated to allow the same striking action. It is preferred that the opening  102  be positioned near the guide plate tip  94  such that the pin  44  is bent when in the driven position. The guide plate  90  is also configured to allow rotation by the blade striker arms  68 . It is preferred that a striker arm notch  104  is provided for each blade striker arm  68  on the side of the guide plate  90  nearest to the cylinder  18 . Each striker arm notch  104  is preferably of sufficient size to accommodate movement of that the blade striker arm  68 . It is also preferred that the guide plate  90  is made of a steel alloy or other durable material to resist damage from extended fastener driving operation.  
      Referring now to  FIGS. 1, 2 , and  3 , at least one bumper pad  106  is provided for absorbing impact energy generated by the hammer arm assembly  58  striking the pin  44 . The bumper pad  106  is preferably made of a resilient material such as rubber and is designed to protect the guide plate  90  and the hammer arm  59  from damaging each other. In the preferred embodiment, the bumper pad  106  is located on the guide plate  90  such that the bumper pad contacts the hammer arm  59  when the hammer arm assembly  58  reaches the second position. In a second embodiment as shown in  FIG. 3 , at least one bumper pad  108  is located on the hammer arm assembly  58  such that the bumper pad contacts the guide plate  90  when the hammer arm assembly reaches the second position.  
      Thus, it will be seen that the frame tool  10  for driving pins into a frame element makes it possible to mechanically drive and bend a pin using a single pneumatic device. The present pin driver  30  is durable, relatively inexpensive and is removable from the frame tool  10  for maintenance purposes.  
      While a particular embodiment of the present frame tool has been described herein, it will be appreciated by those skilled in the art that changes and modifications may be made thereto without departing from the invention in its broader aspects and as set forth in the following claims.