1. Field of the Invention
The present invention relates to a nailer having an improved safety device, and, more particularly, to a nailer having an improved safety device wherein a movable plate, which is adapted to slidably move along a lower surface of a guiding unit, is formed, at a certain location thereof, with an insertion hole for the insertion of a protrusion formed at a trigger, so as to be moved rearward by a predetermined distance under interaction of the insertion hole and protrusion while allowing implementation of a nailing operation when the trigger is pulled in a pressed state of the movable plate, thereby eliminating the risk of causing scratches on a nailing surface of a target structure even if the movable plate is moved while coming into close contact, at a front end thereof, with the nailing surface and consequently, resulting in several advantages, such as for example, easy nailing operation, operator's convenient working posture, and rapid and safe nailing operation.
2. Description of the Related Art
As well known, nailing machines are designed to attach a variety of articles, such as furniture, fabrics, etc., to specific target structures. The nailing machines include a variety of sub-categories on the basis of the kinds of projectile objects used therein. Examples of the nailing machines include a pneumatic tacker, stapler, nailer, pinner, and the like. Generally, the nailing machines serve to attach a variety of materials, such as thin wood boards, fabrics, and the like, to fixed structures made of wood, soft plastics, or the like, by use of pins, staples, tacks, and nails. Nowadays, The nailing machines are widely used by virtue of their several advantages of rapid and convenient use, strong attachment force, etc.
FIG. 1 is a side view illustrating a nailing machine having a safety device according to an exemplary embodiment of the prior art.
Referring to FIG. 1, the conventional nailing machine 2 is of a pneumatic tacker type in which a piston is fitted in a cylinder (not shown) and adapted to be operated by compressed air, so as to hit tacks with a hitting rod (so called “piston driver”) thereof. In the shown conventional pneumatic tacker, the size and shape of a tack ejection port as well as the cross sectional area and shape of a hitting surface portion provided at the hitting rod are selected to coincide with the area and shape of a horizontal push portion of tacks.
Specifically, the conventional nailing machine 2 includes, within a body 4 thereof, a mechanism for generating compressed air required to advance the hitting rod. The body 4 is provided at a rear end thereof with a body cover 6. A magazine 8 is coupled to a front portion of the body 4 at a lower end of the front portion and used to charge a plurality of tacks therein. Also, a guiding unit 16 is provided at an upper end of the magazine 8 and connected to the front portion of the body 4. If tacks are successively raised from the magazine 8, the guiding units 16 allows the tacks to be launched under the action of compressed air.
The magazine 8 is provided at a lower end thereof with a latch 10 to keep the magazine B at a fixed position. The body 4 is provided at a rear portion thereof with a handle 12. The handle 12 extends vertically from a lower end of the rear portion of the body 4. A lower end of the handle 12 is secured to the latch 10 by means of a bracket 14.
A trigger 13 of the conventional nailing machine 2 is provided at a corner of an inner connecting portion between the body 4 and the handle 12. With the manipulation of the trigger 13, tacks can be launched from the nailing machine 2.
In operation of the nailing machine 2 having the above described configuration, if compressed air is introduced into the cylinder to apply a certain pressure to the piston fitted in the cylinder, the piston is advanced to push out tacks, pins, staples, or the like charged in the magazine 8, thus allowing the tacks, etc. to be launched to desired positions by way of the guiding unit 16 in this case, a plunger 29 is mounted in the handle 12 to come into contact with the trigger 13, to impart an opening pressure to the cylinder.
When using the above described conventional nailing machine 2, however, it should be noted that the nailing machine 2 has the risk of fatal accidents if long or large projectile objects including tacks, nails, etc. are launched to unwanted target structures by unintentional trigger pulling manipulation.
To solve the above problem, most conventional large-scale nailing machines, which are designed to launch long projectile objects, such as tacks, nails, etc., have a separate safety device. The safety device serves to allow the trigger 13 to be manually operated only under specific conditions while preventing unintentional launch of projectile objects even when the trigger 13 is pulled.
Conventionally, two types of safety devices have been used in nailing machines. A first type of safety device is provided at a lower surface of the guiding unit 16 so that a contact surface portion thereof is partially exposed to the outside from a front end of the guiding unit 16. Thereby, only when the exposed contact surface portion of the safety device is pressed in a pulled state of the trigger 13, the launch of projectile objects is allowed.
A second type of safety device is adapted to allow the launch of projectile objects only when the trigger 13 is pulled in a state wherein the exposed contact surface portion of the safety device is pushed by a nailing surface of a target structure. The first type of safety device is used when it is required to perform a rapid continuous nailing operation, while the second type of safety device is used when it is required to perform an accurate nailing operation. Meanwhile, it is noted that the above described safety devices have not been used in most small-scale nailing machines.
The above described safety device may be configured to have various configurations, and one example of the various configurations will now be described with reference to FIG. 1. As shown in FIG. 1, the safety device takes the form of an L-shaped movable plate 18, which is forwardly and rearwardly slidable along the lower surface of the guiding unit 16 and adapted to be pressed by the trigger 13. The movable plate 18 acts to allow the trigger 13 to be pulled only when a front end thereof is pressed by a target structure. Accordingly, to accomplish a nailing operation, the movable plate 18 is first positioned to be pressed by the target structure and then, the trigger 13 is pulled. The above described type of safety device shows approximately the same operational manner as in conventional nailing machines shown in FIGS. 1 to 3, except for the fact that the nailing machine shown in FIG. 1 uses a safety device in the form of an L-shaped iron plate, the nailing machine shown in FIG. 2 uses a safety device in the form of an iron wire, and the nailing machine shown in FIG. 3 has an auxiliary trigger as a safety device.
When using the above described safety device, however, since the trigger 13 can be pulled to accomplish a nailing operation only after the movable plate 18 is pressed by the target structure, the conventional nailing machine 2 has problems of inconvenient nailing operation and excessively long nailing time. Furthermore, if the movable plate 18 is moved in a state wherein a front end thereof is pressed by the target structure, there is the risk of imparting scratches to the target structure. Meanwhile, not described reference numeral 20 in FIG. 1 designates an auxiliary lever for achieving rapid opening of a guide cover when tacks are jammed in the guiding unit 16.
Referring to FIG. 2, there is shown a nailing machine having a safety device according to another embodiment of the prior art. The nailing machine 22 comprises the body 4, magazine 8, and guiding unit 16 similar to the above described nailing machine 2 of FIG. 1, but the trigger 13 of the nailing machine 22 is installed to be spaced apart forward from the plunger 29. In this case, an inner trigger piece 28 is provided in a rear end portion of the trigger 13 so that a lower end of the inner trigger piece 28 is coupled to a lower end of the trigger 13.
The nailing machine 22 further comprises a movable wire 24 serving as a safety device. The crooked movable wire 24 has a crooked front end to be inserted into the guiding unit 16 and an L-shaped rear end adapted to press the inner trigger piece 28.
In operation of the above described nailing machine 22, if the front end of the movable wire 24 is pressed by the target structure in a state wherein the trigger 13 is pulled on the basis of a trigger hinge shaft 26 to accomplish a nailing operation, the rear end of the movable wire 24 acts to cause the inner trigger piece 28 to come into close contact with the plunger 29 as the movable plate 24 is moved rearward, thus imparting a pressure force to the inner trigger piece 28. With the pressure force, the inner trigger piece 28 presses the plunger 29, causing the launch of certain projectile objects, such as nails, tacks, pins, or the like.
If the front end of the movable wire 24 serving as the safety device is pressed by the target structure in a state wherein the trigger 13 is not pulled on the basis of the trigger hinge shaft 26, the rear end of the movable wire 24 does not cause the inner trigger piece 28 to come into close contact with the plunger 29 even if the movable wire 24 is moved rearward. In a state wherein the inner trigger piece 28 does not come into close contact with the plunger 29, there is no launch of nails, tacks, pins, or the like.
However, the above described conventional nailing machine 22 also has a problem in that it may cause scratches on the target structure if the movable plate 24 is moved in a state wherein the front end thereof is pressed by the target structure.
Referring to FIG. 3, there is shown the configuration of a safety device mainly used in small-scale nailing machines. As shown in FIG. 3, a conventional small-scale nailing machine 30 comprises the body 4, magazine 8, guiding unit 16, latch 10, handle 12, plunger 29, and body cover 6 similar to the above described nailing machine 2 of FIG. 1. A differentiated feature of the nailing machine 30 is to install an auxiliary trigger 32 as a safety device and a leaf spring 34 to continuously apply a restoration force to the auxiliary trigger 32. The leaf spring 34 is connected to the handle 12 to come into close contact with a lower surface of the trigger 13. The auxiliary trigger 32 is located below the trigger 13 and adapted not to be rotated by a pressure force applied by the trigger 13. In this case, only when the trigger 13 is pulled in a state wherein the auxiliary trigger 32 is rotated by a separate manual force, the nailing machine 30 can accomplish a nailing operation.
Accordingly, to accomplish a nailing operation, the auxiliary trigger 32 has to be pulled rearward prior to pulling the trigger 13. If the trigger 13 is pulled without pulling the auxiliary trigger 32, the lower surface of the trigger 13 comes into contact with an upper end of the auxiliary trigger 32. Accordingly, the trigger 13 cannot be pulled further, and therefore, no nailing operation is accomplished.
When using the auxiliary trigger 32, however, since the operator has to pull the trigger 13 with the first finger in a state of pulling the auxiliary trigger 32 with the second finger, it can be said that the auxiliary trigger 32 actually has less safety effect and has a high risk of causing an unintentional nailing operation. Accordingly, the nailing machine 30 using the auxiliary trigger 32 as a safety device suffers from a rate of accidents.