Abstract:
A wrenching portion provided in an adjuster and employed for assembling is formed at a gripping portion for rotation. The gripping portion is formed in a polygonal shape. In this configuration, the adjuster is decreased in size and weight and its operability of adjusting a driving depth is improved. An undercut portion is removed in a vertical direction and a non-slip rugged portion is provided in only a longitudinal direction so that it can be manufactured in a simple tow-part mold, thereby reducing the production cost.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a nailer having a device for adjusting the driving depth of a nail. 
   2. Description of the Related Art 
   A previously known method for adjusting the level difference between the head of a nail drived by a nailer and the surface of a member-to-be-drived, i.e. driving depth is proposed in JP-A-10-286784. In this known method, the distance between the tip of a push lever in contact with the member-to-be-drived and the tip of the driver blade at a lower dead point, i.e. the projecting quantity S of the driver blade can be made adjustable. 
     FIG. 7  shows the state where a push lever  15  has been pressed to an member-to-be-drived  12  in order to make a driving operation in a drived status of a nailer having a conventional driving depth adjusting device. The push lever  15 , an adjuster  6  and a push lever  16  (hereinafter, these three components are correctively referred to as “a push lever  5 ”) is raised against the load of a spring  17  which is always urged toward the member-to-be-drived  12 , and is further raised in engagement with a switch arm  18 . When the touching surface  19  of the push lever  16  is touched to the touching surface  31  of a push lever guide, the push lever  5  stops to ascend. When a switch  3  is pulled, the driver blade  1  is dropped to drive a nail  2 , thereby determining the driving depth by a projecting quantity S from the tip  13  of the push lever  15  to the tip  11  of the driver blade  1 . Since the push lever  16  is screw-engaged with the adjuster  6 , the adjuster  6  is rotated beforehand to expand/contract the push lever  5 . In this way, the driver blade projecting quantity S in nail driving is determined, thereby adjusting the driving depth. The adjuster  6 , as shown in  FIG. 8 , includes a wrenching portion  7  employed in assembling and a gripping portion  28  for rotation of the adjuster (hereinafter referred to simply “gripping portion”) employed in adjusting the driving depth. The adjuster  6  is generally manufactured by machining or resin molding. 
   SUMMARY OF THE INVENTION 
   In a nailer having a conventional driving depth adjusting device, the wrenching portion  7  and gripping portion  28  are separately formed in the adjuster  6 . Therefore, the adjuster  6  must have a certain length. In the case where the adjuster  6  is manufactured by machining, it cannot be manufactured only by lathing because the wrenching portion  7  must be machined. This leads to the problem of an increase in the production cost. Further, if the diameter of the gripping portion  28  is decreased in order to reduce the size and weight of the adjuster  6 , the rugged portion  8  formed on the rotation gripping portion is slippery, thereby making it difficult to rotate the gripping portion  28 . On the other hand, in the case where the adjuster  6  is manufactured by resin molding, if the shape of the rugged portion  8  for preventing slippage (hereinafter referred to as a non-slip rugged portion), an undercut portion  9  for reducing the weight located at a central position in the longitudinal direction and a spring housing hole  30  for a steel ball for preventing advertent rotation of the adjuster  6 , etc. are taken into consideration, the adjuster cannot be manufactured through simple two-part mold, but must be manufactured through multiple-part mold. This leads to the problem of an increase in the production cost. 
   An object of this invention is to provide a nailer having a driving depth adjusting device which is compact and lightweight and is easy to operate. 
   The above object can be attained by the shape of the adjuster in which a wrenching portion is formed at a gripping portion to shorten the entire length of the adjuster; the gripping portion is formed in a polygonal shape to facilitate the rotation with a rugged portion; and no undercut is provided in a longitudinal direction and the rugged portion is provided in only the longitudinal direction so that it can be manufactured in a simple tow-part mold. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a partial sectional view showing an embodiment of a nailer according to the present invention; 
       FIG. 2  is a partial sectional view for explaining the driving operation in  FIG. 1 ; 
       FIG. 3  is a component-exploded view of a nailer adjusting device in  FIG. 1 ; 
       FIG. 4  is a side view of an adjuster according to this invention; 
       FIG. 5  is an expanded view of the adjuster shown in  FIG. 4  when viewed from arrow C; 
       FIG. 6  is a sectional view of the adjuster taken in line D-D in  FIG. 5 ; 
       FIG. 7  is a partial sectional view showing a conventional nailer adjusting device during a driving operation; and 
       FIG. 8  is a plan view of the adjuster shown in  FIG. 7  and a partial sectional view thereof. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIGS. 1 to 6  show an embodiment of a nailer  10  of this invention. In these figures, a push lever  15  is slidably arranged on a nose  22  and attached at its upper end to an adjuster  6  by a bolt  23 . A projection  24  of the adjuster  6  shown in  FIG. 4  is bolted into a hole  35  ( FIG. 3 ) of the push lever  15  by a bolt  23 . In this case, since the height H of the projection  24  is slightly larger than the thickness of the push lever  15 , the push lever  15  is not tightened and so the adjuster  6  is rotatable. In order to prevent the adjuster  6  from being rotated owing to the shock in nailer driving, a steel ball  26  and a spring  27  are arranged in two grooves  30  which are provided by 180° apart from each other on the one end of the adjuster  6 , respectively. The steel ball  26  is always urged toward the push lever  15  by the spring  27  so that it has sunk by about ⅓ in a groove  26  of the push lever  15  in a relationship between the diameter of the steel ball  26  and the radius of the groove of the push lever  15 . In order to rotate the adjuster  6  from this state, a running torque must be given to the adjuster  6  against the above load so that the steel balls  26  sunk in the grooves  25  of the push lever  15  float onto the upper surface  33  of the push lever  15 . Therefore, the adjuster  6  must be rotated with the rotation gripping portion  28  being firmly gripped by fingers. Since the upper portion of the adjuster  6  is screw-engaged with the push lever  16 , when the adjuster  6  is rotated, the gap D between the adjuster  6  and push lever  16  is increased or decreased. Namely, the entire push lever  5  is expanded or contracted. The push lever  5  is always urged by the spring  17  toward the member to-be-drived. As shown in  FIGS. 4 to 6 , the wrenching portion  7  of the adjuster  6  must have a certain width which permits the torque for tightening the bolt  23  to be received from a wrench. In accordance with this invention, as shown in  FIG. 5 , the wrenching portion  7  is formed at the rotation gripping portion  28 . This makes it unnecessary to provide a large diameter portion separately. Thus, the adjuster  6  itself can be shortened and so the nailer can be downsized. The rotation gripping portion  28 , as shown in  FIG. 5 , is provided with non-slip rugged portions at four positions and formed in a polygonal shape. Therefore, the rotation gripping portion has an outer periphery which is short and effective to rotate the adjuster  6 . Further, since the entire length of the adjuster  6  is short, unlike the conventional adjuster, an undercut portion  9  is not required on the way between the rotation gripping portion  28  and the wrenching portion  7 . In the case where the adjuster  6  is manufactured by resin molding, since there are a screw-hole  29  for engagement between the push levers  15  and  16  at the central portion and grooves  30  each receiving the spring  27  as shown in  FIG. 6 , a molding die must be divided in a longitudinal direction. As described above, since the wrenching portion  7  is formed at the rotation gripping portion  28 , no undercut is provided at the central portion. Therefore, the molding die can be divided in the longitudinal direction. Further, since the non-slip rugged portions are rugged in only the longitudinal direction, the molding die can be divided in the longitudinal direction. 
   With the configuration described above, nail driving is carried out as follows. In the case where the push lever  5  is raised against the spring  17 , which always presses the tip of the push lever  15  onto the member-to-be-drived  12  and hence always urges the push lever  5  toward the member-to-be-drived  12 , as shown in  FIG. 2 , when the touching surface  19  of the push lever  16  is touched to the touching surface  20  of the nose  22 , the push lever  5  stops to ascend. Specifically, the upper dead point of the push lever  16  is predetermined. Therefore, the expansion/contraction of the push lever  5  based on the rotating operation of the adjuster  6  adjusts the position of the tip of the push lever  15  vertically. Near the upper dead point, the upper end of the push lever  16  engages with a plunger  34  and pushes up it. In this state, when the switch  3  is pulled, the driver blade  1  drops abruptly. When the touching surface  31  of the piston is touched to the upper surface  32  of a piston bumper, the driver blade  1  stops to drop, thereby driving a nail  2  from an ejection opening  4 . The driving depth of the nail  2  is determined by the distance from the tip  11  of the driver blade  1  to the tip  13  of the push lever  15 , i.e. the projecting quantity S of the driver blade  1 . In the case where the driving depth is made shallow, if the adjuster  6  is rotated to extend the push lever  5  so that the distance D between the push lever  16  and the adjuster  6  is increased, the adjuster  6  and push lever  15  descend so that the projecting quantity S of the tip  14  of the driver blade  1  decreases. Thus, the driving depth decreases. 
   In accordance with this invention, a wrenching portion is formed at a gripping portion of an adjuster, and the adjuster is formed in a polygonal shape and provided with non-slip rugged portions at several points. The adjuster is also formed in a shape which permits a simple two-part resin molding in a vertical direction. Thus, a driving depth adjusting device can be provided which is compact and lightweight and is easy to operate.