Abstract:
A staple gun comprising a main body and a staple injection nozzle for injecting a staple into a target object, the staple injection nozzle including a nozzle body mounted on a staple striking body and a cover plate for removably closing an upper portion of a staple injection path of the nozzle body so as to guide the staple. The nozzle body has protrusions to receive an end portion of the cover plate and press this cover plate from upward, and an urging member is provided to urge the cover plate in a direction that the end portion of the cover plate intrudes into the protrusions.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a staple gun and in particular to a staple gun. 
     2. Description of the Prior Art 
     Conventionally, there are known staple guns such as those using electric power or compressed air to inject a staple into a target object. 
     FIG. 8 shows a staple injection nozzle  1  for injecting a staple from a staple gun into a target object. This staple injection nozzle  1  has a nozzle body  2  protruding from the front portion of the staple gun. In this nozzle body  2 , a staple injection path  3  is formed through which the stable is injected. The staple (not depicted) has a pair of pins to be struck into a target object and a linking portion connecting these pins. The pins are set in the staple injection path  3  in such a manner that the pins are directed toward the target object. The staple set in the staple injection path  3  is pushed forward from the rear end thereof by a staple driver. 
     The staple injection path  3  has an upper portion closed by a cover plate  4  that can be opened, enabling to remove a staple which has been bent or a plurality of staples which are jammed. 
     In order to fix the cover plate  4 , protrusions  5 ,  5  are provided at the top of two sides of the nozzle body  2 . Bearings  9 ,  9  protrude from a rear portion of the surface of the cover plate  4  having a pin  8  for receiving a hinge portion  7  of a lock lever  6 , so that both ends of a band  10  are rotatably held at both ends of the lock lever  6 . 
     The cover plate  4  is supported on stepped portions  11 ,  11  formed on the side walls of the staple injection path  3 . With the lock lever  6  rotated around the pin  8  to be in a raised state, the linkage portion  12  of the band  10  is set over the protrusions  5 ,  5 . Then, the lock lever  6  is rotated around the pin  8  to be set in a lowered state and the band  10  is in an expanded state, so that the linkage portion  12  of the band is fixed to the stepped portions  11 ,  11 . 
     However, such a staple gun has a problem that when a staple is injected from the staple injection nozzle  1 , a staple may be subjected to a force caused by shock of the staple driver or hardness of a target object, the force tending to open, i.e., remove the cover plate  4  from the nozzle body  2 . Moreover, when a staple is jammed in the staple injection path  3 , the cover plate  4  is subjected to a force to open the cover plate  4  and a large load F is applied from the cover plate  4  directly to the linkage portion  12  of the band  10 . This causes plastic deformation of the linkage portion  12 , thereby lowering the force to push the cover plate  4 . Thus, the cover plate  4  begins to rattle, changing a staple injection orbit, which in turn easily causes a staple jam. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a staple gun capable of suppressing rattle of a cover plate. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     FIG. 1 is an enlarged view of a staple injection nozzle of a staple gun according to an embodiment of the present invention. 
     FIG. 2 is a plan view of the staple injection nozzle of FIG.  1 . 
     FIG. 3 is a side view showing engagement of main protrusions with cover protrusions in the staple injection nozzle of FIG.  1 . 
     FIG. 4 is a cross sectional view showing the staple injection nozzle of FIG. 1 with a cover plate in an opened state. 
     FIG. 5 is a cross sectional view showing the staple injection nozzle of FIG. 1 in a state prior to fixing the cover plate. 
     FIG. 6 is a cross sectional view of the cover plate of FIG. 6 set on the staple injection path and fixed to the staple injection path. 
     FIG. 7 shows an overall configuration of a staple gun having the staple injection nozzle of FIG. 1 to FIG.  7 . 
     FIG. 8 is a partial enlarged view of a conventional staple injection nozzle. 
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Description will now be directed to a staple gun according to an embodiment of the present invention with reference to the attached drawings. 
     FIG. 7 shows a staple gun  20 . The staple gun  20  includes: a staple gun main body  15 ; a handle  21  arranged below the staple gun main body  15 ; a trigger  22  arranged at left of the handle  21 ; and a staple injection nozzle  25  protruding forward from the left end of the staple gun main body  15 . The staple gun main body  15  has a cylinder block  24  and a cylinder head  23 . 
     A coupler  26  is arranged below the handle  21  of the staple gun  20 . The coupler  26  is connected to a coupler (not depicted) of a compressed air supply hose (not depicted). Compressed air supplied from the coupler  26  is introduced to the cylinder head  23  through the interior of the handle  21  when the trigger  22  is pulled. Thus, the compressed air is supplied to the cylinder block  24 . The cylinder block  24  has a built-in piston (not depicted). A staple driver is fixed to this piston. The staple driver extends from the cylinder block  24  to the staple injection nozzle and moves reciprocally in a staple injection path  43  (FIG. 1, FIG. 4 to FIG. 6) in the staple injection nozzle  25  in accordance with the reciprocal movement of the piston. Inside the staple injection path  43 , a staple inlet  43   a  (FIG. 4 to FIG. 6) is formed for supplying U-shaped staples one by one from the staple guide  27  (FIG.  7 ). 
     The staple injection nozzle  25  has a nozzle body  28  attached to the staple gun main body  15  and a cover plate  29  attached to the upper portion of the nozzle body  28 . On the nozzle body  28 , a staple injection path  43  is formed The cover plate  29  defines the upper portion of the staple injection path  43 , so as to guide a staple to be injected, to a target object. At both sides of this cover plate  29 , indentations  29 A,  29 A are formed. Bearings  35 ,  35  are arranged to protrude upward from both sides of rear portion of the cover plate  29 . 
     At both sides of the nozzle body  28 , protrusions  30 ,  30  are formed to be inserted into the indentations  29 A,  29 A of the cover plate  29 , thereby fixing the cover plate  29 . Each of the protrusions  30  is formed in a reversed L shape having a top portion  30   a  extending leftward in the figure. Below the top portions  30   a , a taper surface  31  is formed in such a manner that the its height is gradually lowered toward the back (rightward in FIG.  3 ). The taper surface  31  is brought into abutment with a slanting surface (end portion)  33  of the left end  32  of the indentation  29 A of the cover plate  29 , so that the cover plate  29  is fixed to the nozzle body  28 . 
     As shown in FIG. 4 to FIG. 6, at the back portion of the nozzle body  28 , a plate member  45  is fixed by a bolt  44  so as to define the rear top portion of the staple injection path  43 . This plate member  45  has hooks  39 ,  39  and stoppers  42 ,  42  at its both sides. 
     Moreover, the staple injection nozzle  25  has fixing means  34  for fixing the cover plate  29  to the nozzle body  28 . 
     The fixing means  34  includes: a lock lever  37  whose rear portion is supported by a shaft  36  provided between the bearings  35 ,  35  of the cover plate  29 ; and a spring (urging member) for urging the lock lever  37  backward (rightward in FIG.  2  and FIG.  3 ). The spring  38  is constituted by a C-shaped needle when viewed in a plan view. 
     At both sides of the rear portion of the lock lever  37 , bearing portions  41 ,  41  are provided to protrude downward. In the bearing portions  41 ,  41 , a shaft  36  of bearings  35 ,  35  of the cover plate  29  is movably arranged. Moreover, both ends  38 A,  38 A of the spring  38  are rotatably held in the bearing portions  41 ,  41 , i.e., at a position left (in FIG.  3  and FIG. 6) to the shaft  36  in such a manner that the lock lever  37  is rotated around the both ends  38 A  38 A. 
     As shown in FIG.  3  and FIG. 6, the spring  38  has intermittent portions  38 ,  38 B curved to protrude upward so as to have an elastic force and a rear portion  38 C, which is rotatably held on hook portions  39 ,  39  of the plate member  45 . Moreover, the spring  38  is regulated by stoppers  42 ,  42  of the plate member  45  in its leftward/rightward movement (upward/downward in FIG.  2 ). 
     The hook portions  39 ,  39  have an open rear portion. When the cover plate  29  is opened in a normal condition, the hook portions  39 ,  39  rotatably hold the rear portion  38 C of the spring  38 . When the fixing means  34  is disassembled for repair, the rear portion  38 C can be removed from the hook portions  39 ,  39 . 
     When fixing this cover plate  29  onto the nozzle body  28 , as shown in FIG. 5, the rear portion  38 C of the spring  38  is held on the hook portions  39 ,  39  while the cover plate  29  is set on the staple injection path  43  as shown in FIG.  4 . Here, the lock lever is in its raised state, the cover plate  29  is at a position forward from the position shown in FIG. 3, and the slanting surface  33  of the cover plate  29  is apart from the taper surface  31  of the protrusion  30  of the nozzle body  28 . 
     As the lock lever  37  is tilted forward from this standing state, the lock lever is rotated counterclockwise (in FIG. 4) around the end portions  38 A,  38 A of the spring  38 . This rotation of the lock lever  37  slides the cover plate  29  backward (rightward in FIG.  4 ). When the lock lever  37  is tilted as shown in FIG. 6, the slanting surface  33  of the cover plate  29  is brought into abutment with the taper surface  31  of the protrusion  30  of the nozzle body  28 . 
     The cover plate  29  is urged backward by the urging force of the intermittent portion  38 B of the spring  38 , which in turn pushes the left end  32  of the indentation  29 A of the cover plate  29  under the top portion  30   a  of the protrusion  30 . That is, the cover plate  29  is pushed by the protrusion  30  from upward and firmly fixed to the nozzle body  28 . This engagement is assured by a clearance in the order of 0.5 to 1 mm between the rear portion of the cover plate  29  and the front end  40  of the plate member  45 . 
     When a staple is injected in a state with the cover plate  29  feed to the nozzle body  28 , shock of the staple driver and a hardness of a target object or staple jam generates a force to push the cover plate  29  upward, i.e., to open the cover plate  29 , the force is applied to the taper surface  31  of the top portion  30   a  of the protrusion  30 . However, since the top portion  30   a  of the protrusion  30  protrudes forward, it is possible to prevent opening of the cover plate  29 . 
     Thus, the force pushing the cover plate  29  upward is applied only to the taper surface  31  of the protrusion  30  and not to the spring  38 . Accordingly, there is no danger of expansion of the intermittent portions  38 B,  38 B of the spring  38  and it is possible to keep urging the cover plate  29  backward. Accordingly, it is possible to assure a force to press down the cover plate  29  and firmly fix the cover plate  29  to the nozzle body  28 . Thus, it is possible to surely prevent rattling of the cover plate  29  which would derange the staple injection orbit, easily causing a staple jam.