Abstract:
A portable cutting tool includes: a cutting tool main body having a motor, a rotating blade and a saw cover for covering a part of the rotating blade, a base including a slide surface and a supporting part, and a guide including a pole supported by the supporting part, and a guiding part having a guide surface substantially orthogonal to the slide surface. An interposition member can be disposed so as to interpose between the guide and a side end of the base. The distance between the rotating blade and the guide surface is adjustable by changing a position of the guide. The portable cutting tool includes a contact preventing unit is provided for regulating an adjustment range of the guide to prevent contact of the guide surface and the rotating blade when the guide is attached to the base with the interposition member removed.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a portable cutting tool. A portable electric circular saw is described hereinafter as an example of the portable cutting tool. 
   2. Background Art 
   An example of a conventional portable electric circular saw is shown in  FIG. 1  and  FIG. 2 . 
   As shown in  FIG. 1 , the portable cutting tool includes a rotating blade  1  rotationally driven by a motor (not shown), a cutting tool main body  2  to which the cutting blade  1  is attached, and a base  4  having a slide surface  3  which slides on an upper surface of a material to be cut. The cutting tool main body  2  is connected to the base  4  so as to be rotatable around a supporting shaft  5 . 
   The cutting tool main body  2  has a motor cover  6  which covers the motor, and a gear box  7  which covers a transmitting mechanism part for reducing the rotation speed of the motor with a gear (not shown) and transmitting the rotation to the cutting blade. The motor cover  6  is connected to the gear box  7  with screws (not shown). 
   A saw cover  8  having a shape so as to cover the rotating blade  1  projecting at the other side of the slide surface  3  of the base  4 , or the rotating blade part above the base  4 , is connected to the gear box  7 . A safety cover  9  having a shape so as to cover the rotating blade  1  projecting below the slide surface  3  of the base  4  is urged to the slide surface on the base  4  by a spring (not shown) to be connected to the gear box  8 . Additionally, the safety cover  9  is operable by a lever  10 . 
   A handle  12  having a switch  11  for switching on or off the motor, which is gripped by an operator during work is attached to the motor cover  6 . 
   The handle  12  is gripped and pushed in the arrow A direction (right in  FIG. 1 ) by an operator, thereby cutting a material to be cut advancing in the right direction in  FIG. 1 . Since there is a gap between the handle  12  and the rotating blade  1 , it is difficult to accurately cut along the cut direction A. Therefore, cutting work is usually performed while a guide surface  14  of a guide  13  which is attached to the base  4  as shown in  FIG. 3  is brought into contact with the side surface of the material to be cut. 
   As shown in  FIG. 5 , a circular saw shown in  FIG. 4  is used so that work for cutting a floor material  15  located at the edge of the wall (hereinafter referred to as an edge cutting) is effectively performed. The cutting tool main body  2  is tilted in relation to the base  4  around the rotating shaft  5  so that the circular saw (hereinafter referred to as an edge cutting circular saw) can cut with the cutting blade  1  projecting outside a side end  16  of the base  4  on the opposite side of the motor. 
   The base  4  is rotatable in a range that the cutting tool main body  2  rotates at approximately 12° on the motor side and at approximately 45° on the opposite side of the motor around the supporting shaft  5  provided parallel to a cutting direction by the cutting tool main body  2 , or parallel to an extension surface of the rotating blade  1 . 
   A base side link, in which an arc-shaped long hole is provided around the supporting shaft  5 , is provided at the front part of the base  4  in the cutting direction. Additionally, a main body side link  18 , in which an arc-shaped long hole  17  is provided around the supporting shaft  5 , is provided at the front part of the cutting tool main body  2  in the cutting direction. A bolt is provided as fixing means  19  capable of fixing the cutting tool main body to a desired tilted position by bringing the long hole provided in the base side link into press-contact with the long hole  17  provided in the main body side link  18  with the cutting tool main body  2  tilted in relation to the base  4  at a desired angle. 
   The edge cutting circular saw is formed in such a way that the width of the base  4  is reduced so that the side end  16  on the opposite side of the motor the base  4  is almost located on the extended line of the rotating blade  1 . The rotating blade  1  easily projects outside the side end  16  of the base  4  and the edge cutting is easily performed by this construction. 
   When cutting work other than the edge cutting work is performed with the edge cutting circular saw, a sub-base  20  (see JP-A-2004-188738) for reinforcing the base  1 , of which the width is reduced, shown in  FIG. 6 , or a dust guard  22  capable of sliding on poles  21  of the guide  13  shown in  FIG. 8  and  FIG. 9  and for preventing dust from jetting is attached to the edge cutting circular saw. 
   When the cutting work is performed with the sub-base  20  attached, as shown in  FIGS. 10 to 12 , the work is performed by attaching the guide  12  for accurately cutting. 
   The sub-base  20  and the dust guard  22  are interposition members interposing between the guide and the side end  16  on the opposite side of the motor of the base  4  in a case where a guiding part of the guide  13  is located on the opposite side of the motor, the side end  16  side where the rotating blade projects from the base. 
   Supporting parts  23  into which the pole  21  can be inserted are respectively provided on the front and back of the base  4  in the cutting direction in order to support the poles  21  of the guide  13 , and a guide fixing bolt  25  for fixing the guide  13  movable in a direction parallel to a rotating shaft  24  of the rotating blade  1  at a desired position is provided on the supporting part  23 . By changing the attachment position of the guide  13  to the base  4 , the distance of the rotating blade  1  and the guide surface  14  can be adjusted. 
   As shown in  FIG. 9 , when the guide  13  is moved to the motor side with the dust guard  22  attached, the guide  13  comes into contact with an end surface on the opposite side of the motor the dust guard  22  and the movement thereof is regulated. Therefore, the guide surface  14  of the guide  13  does not come into contact with the rotating blade  1 . 
   Additionally,  FIG. 10  shows a state where the guide  13  is attached to the edge cutting circular saw, to which the sub-base  20  is attached. Since the guide surface  14  of the guide  13  is brought into slidable contact with the side surface of the material to be cut and the cutting tool is guided as shown in  FIG. 11 , the material to be cut can be accurately cut along a marking-off line drawn thereon. 
   Additionally, as shown in  FIG. 12 , when the guide  13  is moved to the motor side with the sub-base  20  attached to the edge cutting circular saw, the guide  13  comes into contact with an end on the opposite side of the motor of the sub-base  20  and the movement thereof is regulated. Therefore, the guide surface  14  of the guide  13  does not come into contact with the rotating blade  1 . 
   Moreover, when the sub-base  20  is attached, a first guide  13 A may be attached. 
   SUMMARY OF THE INVENTION 
   As shown in  FIG. 13  and  FIG. 15 , there is a possibility that some workers attach a guiding part  26  having a guide surface  14  of a guide  13  brought into slidable contact with the side surface of a material to be cut to an edge cutting circular saw so as to locate it at a rotating blade  1  side without attaching a sub-base  20  or a dust guard  22  to the edge cutting circular saw. 
   In this case, since the edge cutting circular saw is formed in such a way that the width of a base  4  is reduced so that a side end  16  of an opposite side of motor of the base  4  is almost located on an extended line of the rotating blade  1 , there is a possibility that the guiding part  26  of the guide  13  comes into contact with the rotating blade  1  or a safety cover  5  as shown in  FIG. 14  and  FIG. 16 . Therefore, there is a possibility that workability and safety are reduced. 
   Additionally, when the guiding part  26  comes into contact with the rotating blade  1 , there is a possibility that the guide  13  is damaged. 
   It is an object of the present invention to provide a portable cutting tool superior in workability, safety and endurance by solving the above-described problems of the conventional arts. 
   The invention provides a portable cutting tool, including: a cutting tool main body having a motor, a rotating blade rotationally driven by the motor and a saw cover having a shape so as to cover a part of the rotating blade; a base that is connected to the cutting tool main body and has a slide surface sliding on an upper surface of a material to be cut, the base including a supporting part; and a guide including a pole supported by the supporting part, and a guiding part having a guide surface substantially orthogonal to the slide surface. An interposition member can be disposed so as to interpose between the guide and a side end of the base. A distance between the rotating blade and the guide surface is adjustable by changing a position in the base to which the guide is attached. The portable cutting tool includes a contact preventing unit for regulating an adjustment range of the guide to prevent contact of the guide surface and the rotating blade when the guide is attached to the base while the interposition member is removed. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention may be more readily described with reference to the accompanying drawings: 
       FIG. 1  is a front view showing a conventional portable circular saw; 
       FIG. 2  is a plan view showing the conventional portable circular saw; 
       FIG. 3  is a perspective view showing a state where a guide is attached to the conventional portable circular saw; 
       FIG. 4  is a plan view showing a conventional edge cutting circular saw; 
       FIG. 5  is a partial cross sectional view showing edge cutting work with an edge cutting circular saw; 
       FIG. 6  is a plan view showing a state where a sub-base is attached to the edge cutting circular saw; 
       FIG. 7  is a plan view showing a state where a dust guard and a conventional guide are attached to the edge cutting circular saw; 
       FIG. 8  is a partial cross sectional view showing cutting work in the state where the dust guard and the conventional guide are attached to the edge cutting circular saw; 
       FIG. 9  is a right side view showing the state where the dust guard and the conventional guide are attached to the edge cutting circular saw; 
       FIG. 10  is a plan view showing a state where the sub-base and the conventional guide are attached to the edge cutting circular saw; 
       FIG. 11  is a partial cross sectional view showing cutting work in the state where the sub-base and the conventional guide are attached to the edge cutting circular saw; 
       FIG. 12  is a right side view showing the state where the sub-base and the conventional guide are attached to the edge cutting circular saw; 
       FIG. 13  is a plan view showing a state where the conventional guide is attached to the edge cutting circular saw; 
       FIG. 14  is a right side view showing the state where the conventional guide is attached to the edge cutting circular saw; 
       FIG. 15  is the plan view showing the state where the conventional guide is attached to the edge cutting circular saw; 
       FIG. 16  is the right side view showing the state where the conventional guide is attached to the edge cutting circular saw; 
       FIG. 17  is a plan view showing a state where a guide of the present invention is attached to the edge cutting circular saw; 
       FIG. 18  is the plan view showing a state where the guide of the present invention is attached to the edge cutting circular saw; 
       FIG. 19  is a right side view showing the state where the guide of the present invention is attached to the edge cutting circular saw; 
       FIG. 20  is a plan view of the guide of the present invention; 
       FIG. 21  is a front view of the guide of the present invention; 
       FIG. 22  is the right side view showing the state where the guide of the present invention is attached to the edge cutting circular saw; 
       FIG. 23  is a plan view showing a state where the dust guard and the guide of the present invention are attached to the edge cutting circular saw; 
       FIG. 24  is a partial cross sectional view showing cutting work in the state where the dust guard and the guide of the present invention are attached to the edge cutting circular saw; 
       FIG. 25  is a right side view showing the state where the dust guard and the guide of the present invention are attached to the edge cutting circular saw; 
       FIG. 26  is a plan view showing a state where the sub-base and the guide of the present invention are attached to the edge cutting circular saw; 
       FIG. 27  is a partial cross sectional view showing cutting work in the state where the sub-base and the guide of the present invention are attached to the edge cutting circular saw; and 
       FIG. 28  is a right side view showing the state where the dust guard and the guide of the present invention are attached to the edge cutting circular saw. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   A mode in which the present invention is applied to a portable circular saw is described hereinafter with reference to  FIGS. 17 to 28 . In these figures, the same symbols are attached to the same elements as  FIGS. 1 to 16 . Therefore, description regarding them will be omitted hereinafter. 
   A guide  13  has a guide surface  14  which comes into slidable contact with the side surface of a material to be cut, a guiding part  26  for guiding a cutting tool by the slidable contact of the guide surface  14  and the side surface of the material to be cut, and at least one pole  21 . 
   As shown in  FIG. 18 , two guides, a first guide  13 A having the guiding part  26  of which the length of a longitudinal direction of the guide surface  14  is the same as that of a side end  16  of a base  4  in a cutting direction, a second guide  13 B having the guiding part  26  of which the length of the longitudinal direction of the guide surface  14  is half as that of the side end  16  of the base  4  in the cutting direction, have been known. 
   The first guide  13 A straddles the rotating blade  1  in the cutting direction, and the two poles  21  are respectively provided in the front and back sides of the guide surface  14  of the first guide  13 A in a direction orthogonal to the guide surface  14 . Each pole  21  is connected to the guiding part  26  via a connection member  27 . The connecting member  27  includes a pole connection part  27 A connected to the pole  21  and a guide connection part  27 B connected to the guiding part  26  having the guide surface  14  brought into slidable contact with the side surface of the material to be cut. 
   As shown in  FIG. 19 , in a case where the first guide  13 A is attached to a cutting tool main body  1  and the guiding part  26  between the pole  21  and the sliding surface  3  of the base  4 , a movement regulating member  28  as contact preventing means for regulating an adjustment range of the guide  13 A and preventing contact of the guide surface with the rotating blade  2  so as to project outside the guide surface  14  of the guiding part  26  is provided in the guide connection part  27 A of the connection member  27 . 
   Additionally, when a sub-base  20  or a dust guard  22  as a interposition member positioned between the guide  13  and the base  4  is attached to the portable circular saw, the connection member  27  comes into contact with a side end (the sub-base side end surface  50  or the dust guard end surface  43  described below) on the opposite side of the motor of the interposition member (the sub-base  20  or the dust guard  22 ) and the movement of the guide  13  is regulated. That is, when the interposition member is attached, the movement regulating member  28  does not come into contact with the side end  16  of the base  4  and does not function. 
   As shown in  FIG. 20  and  FIG. 21 , in the second guide, the pole  21  is provided in a direction orthogonal to the guide surface  14 . An end of the pole  21  is bent so as to be parallel to the guide surface  14 , orthogonal to the pole  21 , and forms into a bent part  29 . When the sub-base  20  as the interposition member positioned between the guide  13  and the base  4  is attached, the bent part  29  comes into contact with the sub-base  20 . An end of the bent part  29  is further bent to be parallel to the pole  21 , and a second guide connection part  29 A connected to the guiding part  26  having the guide surface  14  is formed. 
   The movement regulating member  28 , which projects from the pole  21  and can be brought into contact with the side end  16  of the base  4 , is provided on the pole  21 , and provided at the opposite side of the guide surface of the pole  21  further than the guide surface  14  of the guiding part  26 . 
   When the sub-base  20  as the interposition member is attached as shown in  FIG. 26 , the bent part  29  comes into contact with a side end of the sub-base  20  as shown in  FIG. 28 , the movement regulating member  28  does not come into contact with the base  4 . That is, when the interposition member is attached, the movement regulating member  28  does not come into contact with the end surface  16  of the base and does not function. 
   That is, when the guide  13  is attached to the portable cutting tool with the sub-base  20  or the dust guard  22  positioned between the guide  13  and the base  4  removed, the movement regulating member  28  comes into contact with the base  4  or a saw cover  8  to regulate the movement of the guide  13  and corresponds to the contact preventing means for preventing the guide surface  14  from being contacted with the rotating blade  1  or a safety cover  9 . 
   A first side end  30  of the motor side of the base  4  and a second side end  31  on the opposite side of the motor of the base  4  are formed into a shape almost orthogonal to the slide surface  3  of the base  4 , respectively have a shape of projecting to the cutting tool main body  2 , and form a first side end surface  32  at the motor side and a second side end surface  33  at the opposite side of the motor, respectively. That is, the base  4  has an approximate U-shape as shown in  FIG. 19 . 
   On the base  4 , the poles  21  of the guide  13  can be inserted across the rotating blade  1  in the cutting direction, in turn, in the cutting direction of the base  4 , a second side end surface side front supporting part  34  and a second side end surface side back supporting part  35  which support the guide  13 , are provided at the front and back sides of the second side end surface  33  in the cutting direction, respectively. Additionally, fixing means  36  for fixing the pole  21  of the guide  13  is provided on the base  4 . 
   A first side end surface side front supporting part  37  and a first side end surface side back supporting part  38 , into which the poles  21  are inserted respectively and which respectively have a female screw hole, are provided at the front and back sides of the first side end surface  32  side of the motor side of the base  4  in the cutting direction respectively, and have bolts  39  having male screws which are screwed with the female screw holes of the first side end surface side front supporting part  37  and the first side end surface side back supporting part  38  respectively, and threadably move forward and backward in the direction orthogonal to the slide surface  3 . Further, a knob  40  is provided on the end of the opposite side of the slide surface  3  of the bolts  39 . 
   The knob  40  is rotated by an operator to make the bolt  39  threadably move forward and backward in the female screw hole, an end of the slide surface  3  side of the bolt  39  comes into contact with the pole  21 , thereby fixing the guide  13  at a desired position. That is, an attachment position of the guide  13  to the base  4  is changed so that the distance between the rotating blade  1  and the guide surface  14  can be adjusted. 
   Next, the dust guard  22  and the sub-base  20  will be described, which are attached in a case where an edge cutting circular saw is used for purposes other than the edge cutting and being the interposition member positioned between the guide  13  and the side end  16  of the base  4 . 
   The dust guard  22  is slidably attached to the two poles  21  of the first guide  13 A having the guiding part  26 , of which the length is almost the same as that of the side end  16  of the base  4  in the cutting direction, in order to prevent generated dust from scattering when a material to be cut is cut by the cutting blade  1 . 
   A guide piece  41  for aligning the rotating blade  1  to a marking-off line drawn on the upper surface of a material to be cut is provided at an end side of the longitudinal direction of the dust guard  22 . A side where the guide piece  41  is provided is described hereinafter as the front side of the cutting direction at the time of attachment of the dust guard  22 . 
   The dust guard  22  has two surfaces, a top plate surface  42  almost parallel to an extension surface of the slide surface  3  of the base  4 , and a dust guard side end surface  43  which is an end of the top plate surface  42 , orthogonal to the slide surface  3  of the base  4 , projecting in a direction opposite to the cutting tool main body  2  and located on the opposite side of the motor. As shown in  FIG. 23  and  FIG. 24 , a dust guard front part fixing hole (not shown) and a dust guard back part fixing hole (not shown) are provided in the front and back sides of the top plate surface  42  in the cutting direction respectively, the fixing holes respectively having a female screw part. Dust guard fixing bolts  44  and  45  are provided having male screws which are screwed to the female screw parts of the dust guard front part fixing hole and the dust guard back part fixing hole respectively and threadably move forward and backward in the direction orthogonal to the slide surface  3 . Further, knobs  46  are provided on ends of the opposite side of the slide surface  3  of the dust guard fixing bolts  44  and  45  respectively. 
   The dust guard fixing bolts  44  and  45  threadably move forward and backward and come into contact with the poles  21  of the first guide  13 A respectively so that the dust guard  22  can be fixed to the desired position on the pole  21 . 
   When the dust guard  22  is attached to the first guide  13 A, an end of slide surface  3  side of the dust guard side end surface  43  is located on the opposite side of the motor, the cutting tool main body  2  side is located further than the slide surface  3 . That is, when the dust guard  22  is attached to the first guide  13 A, the dust guard  22  is located at the position not be in contact with a material to be cut. 
   Additionally, approximate L-shaped saw cover contact parts  47  capable of coming into contact with the saw cover  8  are provided on the front and back sides of the top plate surface  42  of the dust guard in the cutting direction respectively. When the cutting tool main body  2  is rotated to the opposite side of the motor with the fixing of the dust guard  22  and the first guide  13 A released, the dust guard  22  slides on the poles  21  of the first guide  13 A to the opposite side of the motor in accordance with the rotation of the cutting tool main body  2  owing to the contact of the saw cover contact part  47  and the saw cover  8 . 
   The sub-base  20  having a sub-base slide surface  48 , which is almost the same surface as the slide surface  3  of the base  4  and slidable on the upper surface of a material to be cut, is attached to the base  4  in order to reinforce the base  4  reduced in the width direction of the edge cutting circular saw. The sub-base  20  has two sub-base poles  49 , crossing the rotating blade  1 , in the longitudinal direction. 
   Sub-base supporting parts (not shown), into which the sub-base poles  49  are inserted respectively and which support the sub-base  20 , are provided on the front and back sides of the base  4  in the cutting direction, respectively, in addition to the supporting parts for supporting the guide  13  which are provided on the base. 
   As shown in  FIG. 27  and  FIG. 28 , the sub-base  20  is in an approximate L-shape, and an end of the sub-base  20  in the width direction, a direction orthogonal to the cutting direction, projects in a direction orthogonal to the sub-base slide surface and forms a sub-base side end surface  50 . A guide part (not shown) recessed so as to guide the pole  21  of the guide  13  is provided on the sub-base side end surface  50 .