Patent Application
20050205638
1. Field of the Invention
This invention relates to a nail gun, particularly to a single orderly striking device for a nail gun, which can effectively prevent a nail from stricken in vain or intermittently, attaining smooth orderly striking for a single nail of packed nails one by one.
2. Description of the Prior Art
In using a conventional nail gun, a user has to place one end of a safety arm of the nail gun on the surface of a work, with the other end of the safety arm pushing a press plate pivotally connected with a trigger. Then the trigger is pulled to force the press plate to activate a valve switch so that pressured air may flow into a cylinder to push and move a piston with a striking needle, which then moves forward very fast to strike a nail in a work. During the striking process, the piston slides through a one-way wind hole in the wall of the cylinder and allows pressured air to flow through the one-way wind hole into a lower air chamber. Then the pressured air flowing in the lower air chamber may flow back to the front section of the cylinder before the end of the piston through a return wind hole in the wall of the cylinder so that the striking piston may be pushed back to its original position for a next round of striking another nail.
On the other hand, at the moment of striking a nail by the nail gun, the safety arm receives reaction to jump off the surface of the work, forcing the other end of the safety arm to separate from the press plate of the trigger, which then may rotate to return to its original position, with the valve switch also moved back to turn-off condition, stopping pressured air from flowing continually into the cylinder for moving the piston, which returns to its original position to be ready for next striking.
However, a nail may not be possible to be continually stricken orderly but be stricken intermittently or in vain, mainly because of the surface of a work being too hard or some other cause, with the striking needle of the piston unable to strike a nail completely into the work and with the piston moved to slide only half its stroke and stop at a middle way hiding the wind hole so pressured air cannot flow into the lower air chamber. Thus, the piston cannot be moved back by pressured air and stops at a half way and cannot move back to its original position. In addition, the nail gun may get a reaction to instantly jump off the surface of the work at the moment when the striking needle of the piston strikes to push a nail into the work. Then the other end of the safety arm may leave off the press plate of the trigger at that moment, letting the press plate pivotally return to its original position and no longer press the air valve switch, and accordingly the valve switch is moved to its turned-off position, with pressured air impossible to flow into the cylinder to push the piston back to its original position. Therefore, even if a user pushes the safety arm to the surface of the work once again for next round of striking action, the next nail is impossible to enter the nozzle of the nail gun because of the striking needle still staying therein and hampering the next nail from entering. Thus a nail cannot orderly be stricken out, resulting in nails stricken intermittently or in vain. Then the nail gun cannot work again, unless a user waits until the piston recovers its original position. Then this erroneous operation can cause great inconvenience to a user.
This invention has been devised to offer a single orderly striking device for a nail gun. The device includes a projection formed on a press plate positioned just behind the trigger of a nail gun, and the projection always contacts and pushes a valve switch so as to let pressured air continue flowing into the cylinder of the nail gun, even if the piston stops at a middle way in its stroke and blocks a wind hole of a wall of the cylinder. Then the safety arm has its inner end leaving off the press plate, so when the press plate recovers its original position, the projection still keeps on pushing the valve switch, permitting pressured air continue to flow into the cylinder to move the piston with a striking needle forward, clearing the blocked wind hole. Therefore, the erroneous action of the nail being stricken intermittently or in vain can be prevented.
This invention will be better understood by referring to the accompanying drawings, wherein:
A preferred embodiment of a single orderly striking device for a nail gun in the present invention, as shown in
The press plate 30 has a pivot wound ear 31 formed at a lower end for pivotally fixing itself at a preset position behind the trigger 10, and a projection 32 formed integral and recessed inward by pressing process at an upper section to contact and push always a front end of the valve switch 50. The projection 32 has a height for the trigger 10 always in the condition 32 resting against the press plate 30. When the safety arm 40 leaves off the press plate 30, the projection 32 still presses the valve switch 50 to be kept in an open condition so that pressured air may continue to flow into the cylinder 60 for pressing and moving the piston 70, in stricken or in vain.
Next, the normal condition and the special condition of the press plate 30 are to be described as below.
(1) In the normal condition: referring to
(2) The special condition: Should a nail not be smoothly stricken into a work after triggering of the nail gun and should the piston 70 stop at the middle of its stroke blocking the wind holes 61 of the cylinder 60, the projection 32 of the press plate could overcome this condition. In detail, a user pushes the safety arm 40 according to the processes shown in
While the preferred embodiment of the invention has been described above, it will be recognized and understood that various modifications may be made therein and the appended claims are intended to cover all such modifications that may fall within the spirit and scope of the invention.
