Abstract:
A safety is incorporated in a nailing device, which ensures operation safety of the nailing device. The nailing device includes a housing in which a striker plate is mounted and movable to a ready-to-strike position for subsequently striking a nail out of the housing. The safety includes a retainer pivoted to the housing with an inner end engaging the striker plate to retain the striker plate against movement to the ready-to-strike position and an opposite outer end engaging a release plate that is biased by a spring to partially projecting beyond the housing. When the nailing device is properly set on a work piece, the release plate is forced against the biasing spring back into the housing and the inner end of the retainer is caused to disengage from and thus freeing the striker plate.

Description:
BACKGROUND OF THE INVENTION 
   (a) Technical Field of the Invention 
   The present invention relates to a safety for nailing devices, and in particular to a safety that, unless released, prevents the nailing device from operation by blocking a nail striker plate, in order to ensure operation safety of the nailing device. 
   (b) Description of the Prior Art 
   A nailing device functions to repeatedly and forcibly feed out nails for fixing different parts or articles together. A regular nailing device comprises a nail striker plate that is arranged inside a housing and movable up and down in a given direction. A strip of nails is accommodated in a bottom portion of the housing and is fed forward by a nail forwarding unit to locate below the striker plate for being struck out of the housing. The striker plate is movable either manually, electrically or pneumatically to a lifted, ready-to-strike position from which the striker plate is release to spontaneously strike out the nail located therebelow. Since the nailing device can be easily operated and provide efficient nailing operation, it has been widely used in for example carpentry. 
   A conventional nailing device is operated by lifting the striker plate to set the striker plate in a ready-to-strike condition. To avoid undesired operation of the nailing device, taking a manually operated nailing device as an example, a safety ring is provided on the housing of the nailing device to secure, in a releasable manner, an operating handle whereby mistakenly operating the handle to cause undesired percussion of nail can be eliminated. In use of the nailing device, the safety ring must be released to allow the nailing device to be set in a ready-to-strike condition, and therefore inadvertent percussion at the time that the nailing device is not properly set on a work piece may happen, which may hurt the operator or other persons standing nearby by shooting uncontrolled nail. 
   To cope with such a problem, Taiwan Patent No. 1281432 discloses a nailing device comprising a housing in which a safety bar is movably arranged in such a way that the safety bar is normally projecting out of a bottom of the housing. The safety bar functions to prevent an engaging portion formed on a handle from engaging an opening defined in a striker plate. When the nailing device is properly set on a work piece, the safety bar is forced into the housing, allowing the handle to engage the striker plate for setting the nailing device in a ready-to-strike condition. As such, inadvertent percussion of the nailing device can be avoided. 
   The known device uses a biasing torque provided by a torsion spring to disengage the engaging portion of the handle from the opening of the striker plate in order to realize prevention of inadvertent percussion. However, when the operator of the nailing device applies a force that exceeds the spring force, the engaging portion of the handle may also get back into engagement with the opening of the striker plate to cause undesired percussion. Apparently, the known device is not capable to fully eliminate the potential risk of inadvertent percussion. 
   Since the force that strikes the nail out of the housing of the nailing device is very significant, if the nail is undesirably shot to a human body, damage may be resulted. This is even worse if the nail shoots at the eyes, which may lead to loss of sight. Thus, it is important that inadvertent percussion of the nailing device can be definitely excluded unless the nailing device is properly set on a work piece to thereby ensure operation safety of the nailing device. 
   In view of the above discussion, the present inventor has engaged in researches in the related fields, attempting to ensure an improvement that secures the operation safety of a nailing device by incorporating a novel safety to eventually and completely overcome the problem associated with inadvertent percussion of the conventional nailing devices. 
   SUMMARY OF THE INVENTION 
   The primary purpose of the present invention is to provide a safety for a nailing device that eliminates inadvertent percussion of the nailing device to secure the operation safety of the nailing device. 
   The objective can be realized with the following construction of nailing device, which comprises a housing, a striker plate that is slidably arranged in a front end portion of the housing, a spring plate that applies a strong driving force to the striker plate set in a ready-to-strike position to make the striker plate performing downward striking, and a handle that selectively drives the striker plate to the ready-to-strike position. In accordance with the present invention, a safety is provided, accommodated in the housing in front of the striker plate. 
   The safety comprises a release plate, a retainer, and a recoiling spring. The release plate is movably mounted in the housing and is movable in a direction similar to a moving direction of the striker plate. The release plate is arranged to be normally and partially projecting beyond a bottom of the housing but is not allowed to separate from the housing. The retainer is rotatably mounted to the housing and has first and second end portions respectively corresponding to and engaging the release plate and the striker plate. The recoiling spring is arranged above the first end portion of the retainer to bias the release plate to normally project beyond the bottom of the housing with the second end portion of the retainer retaining the striker plate against movement to the ready-to-strike position. When the release plate is caused to move against the recoiling spring to get back into the housing, for example by being positioned on a work piece, the retainer is rotated to have the second end portion thereof moved in such a manner to disengage from the striker plate thereby releasing the striker plate from being retained against upward movement to the ready-to-strike position. 
   With such an arrangement, the safety of the present invention comprises a retainer that effectively prevents the striker plate to be moved to the ready-to-strike position until the release plate is forced back into the housing. Thus, unless the nailing device is properly set on the surface of a work piece, which forces the release plate back into the housing of the nailing device, the striker plate cannot be moved to the ready-to-strike position. In this way, operation safety of the nailing device during regular uses can be secured. 
   The foregoing object and summary provide only a brief introduction to the present invention. To fully appreciate these and other objects of the present invention as well as the invention itself, all of which will become apparent to those skilled in the art, the following detailed description of the invention and the claims should be read in conjunction with the accompanying drawings. Throughout the specification and drawings identical reference numerals refer to identical or similar parts. 
   Many other advantages and features of the present invention will become manifest to those versed in the art upon making reference to the detailed description and the accompanying sheets of drawings in which a preferred structural embodiment incorporating the principles of the present invention is shown by way of illustrative example. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a portion of a nailing device of which a housing is broken to illustrate a safety constructed in accordance with the present invention; 
       FIG. 2  is an exploded view of the portion of the nailing device in accordance with the present invention, illustrating the spatial relationship among the parts thereof; 
       FIG. 3  is a cross-sectional view of the nailing device incorporating the safety of the present invention; 
       FIG. 4  is a cross-sectional illustrating the nailing device is properly set on a work piece to start the nailing operation; 
       FIG. 5  is similar to  FIG. 4  but illustrating when a handle is operated to cause a striker plate to move toward a lifted, ready-to-strike position; 
       FIG. 6  is similar to  FIGS. 4 and 5 , and illustrating the striker plate is forcibly driven downward by a spring plate to strike a nail into the work piece; and 
       FIG. 7  is a cross-sectional illustrating the nailing device in a condition when the safety is not released. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The following descriptions are of exemplary embodiments only, and are not intended to limit the scope, applicability or configuration of the invention in any way. Rather, the following description provides a convenient illustration for implementing exemplary embodiments of the invention. Various changes to the described embodiments may be made in the function and arrangement of the elements described without departing from the scope of the invention as set forth in the appended claims. 
   With reference to the drawings, and in particular to  FIGS. 1 and 2 , a safety is provided for preventing a nailing device from being accidentally triggered to shoot a nail in an unexpected manner. As shown in the drawings, the nailing device in which the safety in accordance with the present invention is embodied comprises a housing  10 , a nail striker plate  11  arranged in a front end portion of the housing  10 , a spring plate  14  that provides a sufficient biasing force to the striker plate  11 , and a handle  15  for manually lifting the striker plate  11  against the spring plate  14 . The striker plate  11  is accommodated in the front end portion of the housing  10  in a slidable manner and serves to strike out nails  30  that are lined up under the striker plate  11 , see  FIG. 3 . The striker plate  11  forms a spring hole  12  for receiving a front tip of the spring plate  14  and a driving hole  13  that is operatively coupled to the handle  15 . The handle  15  is provided, at a front end thereof, with a driving member  16  that engages the driving hole  13  of the striker plate  11 . The handle  15  is preferably constructed for manual operation to drive the striker plate  11  to the lifted position and, in the following description, an example of manually operable handle  15  will be given for explanation of the present invention. The safety constructed in accordance with the present invention, which is generally designated with reference numeral  20 , is arranged in the front end portion of the housing  10  to be in front of the striker plate  11  to prevent undesired percussion of the striker plate  11  at the time when the nailing device is not properly positioned against a work piece. 
   In the following description, a preferred embodiment of the safety  20  constructed in accordance with the present invention will be illustrated with reference to  FIGS. 1-3 . The housing  10  comprises a rail  18  for guiding movement of the striker plate  11  in upward and downward directions. In the embodiment illustrated, the rail  18  is in the form of a plate having opposite lateral edges bent to form opposing channels for slidably receiving opposite edges of the striker plate  11 ; however, it is apparent that the rail  18  can be embodied in different form, while maintaining the same function as will be described herein. The rail  18  has a top edge in which a notch  19  is defined. The safety  20  comprises a release plate  23 , a retainer  24 , and a recoiling spring  28 . The release plate  23  is slidably received in a chute  21  defined in the housing  10  so as to be movable in the same direction as the striker plate  11 . The chute  21  has opposite banks corresponding opposite edges of the release plate  23  and each bank and the associated edge of the release plate  23  form engageable fixing means  22 ,  24 . The fixing means  22 ,  24  engage each other in such a way to enable limited relative movement of the release plate  23  with respect to the housing  10  without separation. Also, the engagement between the fixing means  22 ,  24  serves to prevent the striker plate  11  from being undesirably lifted. This will be further discussed. In the embodiment illustrated, the fixing means  22 ,  24  are, respectively, a pawl and a corresponding notch that is extended in the movement direction of the release plate  23  to a desired length for movably receiving the pawl therein to establish the engagement therebetween. The engagement of the pawl  22  and the notch  24  is such that a lower end portion is normally projecting beyond a bottom of the housing  10  to a desired length. The retainer  25  is pivotally mounted in the housing  10  by a pivot  26  and located above the release plate  23  and substantially corresponding to a constraint hole  29  defined in the striker plate  11  whereby end sections of the retainer  25  that are located on opposite sides of the pivot  26  are respectively corresponding to the release plate  23  and the constraint hole  29  of the striker plate  11 . The shape of constraint hole  29  of the striker plate  11  and the spatial relationship among the retainer  25 , the release plate  23  and the constraint hole  29  are such that the retainer  25  is allowed to rotate in a predetermined direction to have the end portion of the retainer  25  corresponding to the constraint hole  29  (which will be referred to the constraint-hole-side end portion) moved downward, but not in the reversed direction to move the constraint-hole-side end portion upward. In the embodiment illustrated, the constraint hole  29  is shaped and sized to allow the constraint-hole-side end portion of the retainer  25  to be partially and movably received therein. The constraint-hole-side end portion of the retainer  25  is provided with an inclined face  27 , which functions to eliminate the interference of the retainer  25  with the downward striking movement of the striker plate  11 . The recoiling spring  28  is arranged above the end portion of the retainer  25  that is opposite to the constraint-hole-side end portion to bias the retainer  25  in such a way that the constraint-hole-side end portion of the retainer  25  is normally received in the constraint hole  29  of the striker plate  11  to limit the upward movement of the striker plate  11  thereby preventing the striker plate  11  from being lifted. 
   With such an arrangement, when the nailing device is not set in a normal operation condition where the nailing device is positioned against for example a work piece, the striker plate  11  cannot be lifted by operation of the handle  15  for percussion. Thus, accidental or undesired triggering to shoot nails can be prevented and accordingly, a safety for a nailing device is realized. 
   For practical operation of the nailing device of the present invention, as shown in  FIGS. 3-6 , when a nailing operation is desired, an operator positions the nailing device against a surface of a work piece on which the nailing operation is to be carried out. By doing so, the surface of the work piece forces the release plate  23  of the safety  20  into the housing  10  and causes the release plate  23  to move upward. The upward movement of the release plate  23  drives the end portion of the retainer  25  corresponding to the release plate  23  to simultaneously move upward, leading to rotation of the retainer  25  about the pivot  26  and compression of the recoiling spring  28  located above the retainer  25  to enable storage of potential energy therein. As a result of the rotation of the retainer  25 , the constraint-hole-side end portion of the retainer  25  disengages from the constraint hole  29  thereby opening the safety  20 , as shown in  FIG. 4 . The operator may then actuate the handle  15  and the driving member  16  of the handle  15 , which engages the driving hole  13  of the striker plate  11 , drives the striker plate  11  toward the lifted, ready-to-strike position. Meanwhile, the spring plate  14  is deflected upward, as shown in  FIG. 5 , and a recoiling force is established. Once the striker plate  11  is sufficiently moved upward to the lifted position, the driving member  16  of the handle  15  is allowed to disengage from the driving hole  13  of the striker plate  11  and the striker plate  11  is released so that the striker plate  11 , under the action of the recoiling force provided by the spring plate  14 , is strongly and forcibly driven downward to strike the nail  30  located therebelow into the work piece, as shown in  FIG. 6 . This completes the nailing operation. After that, the striker plate  11 , the release plate  23  and the retainer  25  are all returned to their original positions to get ready for next nailing operation. 
   On the other hand, if the nailing device is not properly positioned against the surface of the work piece, then as shown in  FIGS. 3 and 7 , the retainer  25  of the safety  20  is subjected to the biasing force of the recoiling spring  28  to maintain the release plate  23  in the condition of downward projecting beyond the housing  10  and the constraint-hole-side end portion of the retainers  25  is set in the constraint hole  29 . Thus, when the operator attempts to operate the handle  15  for causing the driving member  16 , which engages the driving hole  13  of the striker plate  11 , to drive the strike plate  11  upward, the constraint hole  29  of the striker plate  11  engages the retainer  25  (or more precisely, as illustrated in the drawings, a bottom wall of the constraint hole  29  abuts a bottom face of the constraint-hole-side end portion of the retainer  25 ) and the retainer  25  is blocked by the release plate  23 , which is in turn fixed with respect to the chute  21  by the fixing means  22 ,  24  in the upward direction, whereby the striker plate  11  is prevented from moving upward by the operator&#39;s attempt. Thus, a secured condition of the safety  20  is ensured. And, consequently and as shown in  FIG. 7 , the striker plate  11  cannot be moved upward to the lifted, ready-to-strike position. In this way, undesired movement of the striker plate  11  up to the lifted, ready-to-strike position is prevented and the nailing device cannot shoot nails in a condition where the nailing device is not properly set on a surface of a work piece. Undesired and accidental percussion of the nailing device is thus eliminated. 
   It will be understood that each of the elements described above, or two or more together may also find a useful application in other types of methods differing from the type described above. 
   While certain novel features of this invention have been shown and described and are pointed out in the annexed claim, it is not intended to be limited to the details above, since it will be understood that various omissions, modifications, substitutions and changes in the forms and details of the device illustrated and in its operation can be made by those skilled in the art without departing in any way from the spirit of the present invention.