Abstract:
According to an aspect of the present invention, there is provided a bench cutting machine including: a motor that drives a cutting blade; a fan that is driven by the motor to generate a fan air; a base portion; a cutting portion that accommodates the cutting blade over the base portion; and a supporting portion that movably supports the cutting portion, wherein rotational directions of the fan and the cutting blade are arranged to be the same.

Description:
TECHNICAL FIELD 
       [0001]    An aspect of the present invention relates to a bench cutting machine, and particularly to a bench cutting machine including a mechanism which discharges dusts. 
       BACKGROUND ART  
       [0002]    In a conventional bench cutting machine as shown in JP-H11-170214-A, the dusts when a work piece is cut by a rotationally-driven cutting blade are guided to a dust guide passage by the inertial force and the airflow generated by the cutting blade, and the dusts are collected in a garbage collection bag outside the bench cutting machine from the dust guide passage. 
         [0003]    In the bench cutting machine shown in JP-H11-170214-A, a rotary shaft of a motor is provided with a fan, and the motor is cooled by the fan air generated by the fan. Since the rotational direction of the motor and the rotational direction of the cutting blade are opposite directions, a vortex of the fan air generated by the fan is canceled by the airflow generated by the rotated cutting blade. In the above-described bench cutting machine, the dusts are discharged to the outside of the machine by the airflow generated by the cutting blade. In this case, when the fan air is discharged to the dust guide passage case, the guide efficiency of the dusts may be lowered. 
       SUMMARY OF INVENTION  
       [0004]    One of the objects of the invention is to provide a bench cutting machine which more suitably discharges the dusts to the outside during cutting. 
         [0005]    According to an aspect of the present invention, there is provided a bench cutting machine including: a motor that drives a cutting blade; a fan that is driven by the motor to generate a fan air for cooling the motor; a base portion that supports a member to be worked; a cutting portion that is provided on the base portion and that accommodates the cutting blade over the base portion; and a supporting portion that is connected to the base portion and that supports the cutting portion so that a position of the cutting blade with respect to the base portion is adjustable, wherein the motor is arranged on the lateral side of the cutting blade, wherein the cutting portion includes: a housing that houses the motor, the fan and a portion of the cutting blade; and a transmission mechanism that is housed within the housing and that transmits a power of the motor to the cutting blade, wherein the transmission mechanism is configured so that a rotational direction of the fan and a rotational direction of the cutting blade become the same, and wherein the housing includes: a motor housing portion that houses the motor; a cutting blade housing portion that houses the portion of the cutting blade; a dust discharge port that communicates the cutting blade housing portion with an outside thereof; and a passage that communicates the motor housing portion with the cutting blade housing portion so as to allow the fan air to flow into the cutting blade housing portion. 
         [0006]    According to such a configuration, since the rotational directions of the fan and the cutting blade are aligned, the direction of a vortex of the fan air generated by the fan becomes the same direction as the rotational direction of the cutting blade. Therefore, when this fan air is made to flow into the cutting blade housing portion from the introduction passage, the fan air can be kept from disturbing the flow of the airflow caused by the rotation of the cutting blade, and the vigor of the airflow can be strengthened by the downstream of the fan air. Therefore, the guide efficiency of the dusts which are guided and discharged to the dust discharge port by the airflow can be enhanced, and the dusts can be suitably discharged from the dust discharge port. 
         [0007]    The fan may be directly driven by the motor. And, the transmission mechanism may include: a first gear that is directly driven by the motor; a final gear that rotates coaxially and integrally with the cutting blade; and an intermediate gear that meshes with the first gear and the final gear and that transmits a rotation of the first gear to the final gear. 
         [0008]    The intermediate gear may transmit the rotation of the first gear to the final gear while decelerating. 
         [0009]    According to such a configuration, the rotational directions of the fan and the cutting blade can be aligned with a simple configuration. 
         [0010]    The fan may be a centrifugal fan. 
         [0011]    According to such a configuration, a vortex can be more suitably formed. 
         [0012]    A rotary shaft of the motor may be arranged parallel to a rotary shaft of the cutting blade. 
         [0013]    According to such a configuration, the vigor of the airflow of a cutting blade can be most suitably strengthened by the vortex. 
         [0014]    A rotary shaft of the motor may be arranged oblique to a rotary shaft of the cutting blade. 
         [0015]    A plurality of ribs may be formed within the passage in the housing. 
         [0016]    In a cross-sectional plane orthogonal to a rotary shaft of the cutting blade, each rib may radially extend from the rotary shaft of the cutting blade. 
         [0017]    According to such a configuration, the portion of the housing in which the introduction passage is formed can be reinforced, and the fan air which flows through the inside of the introduction passage can be corrected. 
         [0018]    An air intake port is formed on the motor housing portion at a side opposite to the cutting blade housing portion. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0019]      FIG. 1  is a side view of a bench cutting machine according to an embodiment of the invention. 
           [0020]      FIG. 2  is a front view of the bench cutting machine according to the embodiment. 
           [0021]      FIG. 3  is a sectional view of a cutting portion of the bench cutting machine according to the embodiment. 
           [0022]      FIG. 4  is a sectional view taken along the line IV-IV of  FIG. 3 . 
           [0023]      FIG. 5  is a sectional view taken along the line V-V of  FIG. 3 . 
           [0024]      FIG. 6  is a sectional view of a gear case of the bench cutting machine according to the embodiment. 
           [0025]      FIG. 7  is a view showing a cutting state of the bench cutting machine according to the embodiment (a state before cutting). 
           [0026]      FIG. 8  is a view showing a cutting state of the bench cutting machine according to the embodiment (a state during cutting). 
           [0027]      FIG. 9  is a conceptual view showing the relationship between a vortex and an airflow of the bench cutting machine according to the embodiment. 
           [0028]      FIG. 10  is a view showing a cutting state of the bench cutting machine according to the embodiment (a cutting completion state). 
           [0029]      FIG. 11  is a side view of the bench cutting machine according to a modification of the embodiment. 
           [0030]      FIG. 12  is a sectional view of a cutting portion of the bench cutting machine according to a modification of the embodiment. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0031]    Hereinafter, a bench cutting machine according to an embodiment of the invention is described with reference to  FIGS. 1 to 10 . A bench cutting machine  1  that is a bench cutting machine shown in  FIG. 1  is a bench cutting machine including a sliding mechanism, and mainly includes a base portion  2 , a supporting portion  3 , a cutting portion  4 , and a cutting blade  7 . 
         [0032]    The base portion  2  mainly includes a base  21  which carries timber W that is a member to be cut, a turntable  22  rotatably carried on the base  21 , and a fence  23  provided at the base  21 . The base  21 , as shown in  FIG. 2 , includes a pair of a left base  21 A and a right base  21 B. The direction in which the left base  21 A and the right base  21 B are aligned is defined as a right-left direction, the upside of the surface of the base  21  ( FIG. 1 ) on which the timber W is placed defined as the upside, and the side opposite to the upside is defined as the downside. 
         [0033]    As shown in  FIG. 2 , the turntable  22  is arranged between the right base  21 B and the left base  21 A. As shown in  FIG. 1 , the turntable  22  includes a substantially truncated conical turntable body portion  22 A, a protruding portion  24  which protrudes towards one side of the turntable body portion  22 A, and a cutting portion supporting portion  27  which supports a supporting portion  3  which is provided on the other side of the protruding portion  24  and which will be described later. The direction in which the protruding portion  24  protrudes from the turntable, and which intersects the right-left direction is defined as the front, and the side opposite to the front is defined as the rear. 
         [0034]    Additionally, a series of grooves (not shown) are formed from a position near the cutting portion supporting portion  27  to the protruding portion  24  in an upper surface  22 B of the turntable  22 . The grooves (not shown) serve as parts which house the blade edge of the cutting blade  7  in the same position as the line of intersection when the cutting blade  7  rocks downward, and intersects the turntable  22 . 
         [0035]    As shown in  FIGS. 1 and 2 , the protruding portion  24  is provided with a regulation operating portion  28  used as an operating portion when the rotation of the turntable  22  with respect to the base  21  is regulated. As shown in  FIG. 1 , the cutting portion supporting portion  27  is arranged in the position opposite to the protruding portion  24  with respect to the central axis of the turntable  22 . The cutting portion supporting portion  27  has a tilt shaft  27 A located on an extension line of the grooves (not shown) , and a tilt supporting portion  27 B to which the supporting portion  3  is fixed at an arbitrary inclination angle. 
         [0036]    As shown in  FIG. 1 , the fence  23  is provided in the position above the turntable  22  on the base  21 . As shown in  FIG. 2 , the fence  23  includes a left fence  23 A and a right fence  23 B corresponding to the left base  21 A and the right base  21 B, the front faces of the left fence  23 A and the right fence  23 B are arranged so as to be located on the same plane, thereby specifying the position of the timber W ( FIG. 1 ). 
         [0037]    As shown in  FIG. 1 , the supporting portion  3  mainly includes a tilting portion  31 , sliding pipes  33 , a sliding portion  34 , and a rocking portion  35 . The tilting portion  31  is supported by the tilt shaft  27 A, and is configured so as to be able to be fixed to the tilt supporting portion  27 B by a clamp  31 A. By loosening the clamp  31 A, the tilting portion  31  and the cutting portion  4  connected to the tilting portion  31  can be tilted with respect to the base portion  2 , and by fastening the clamp  31 A, the tilting portion  31  is fixed to the cutting portion supporting portion  27 B, and the cutting portion  4  maintains a predetermined tilting angle with respect to the base portion  2 . The sliding pipes  33  are constituted by two tubular bodies and are fixed to the tilting portion, and as shown in  FIG. 2 , the two tubular bodies are arranged in parallel in an up-down direction, and extend from an upper portion of the tilting portion  31  parallel to the upper surface of the base portion  2 . The sliding portion  34  is mounted on the sliding pipes  33 , and is configured so as to be slidable back and forth with respect to the sliding pipes  33 . The rocking portion  35  is provided at the sliding portion  34 , and is constituted by a pair of arm portions. A rocking shaft portion  35 A is laid between a pair of arm portions, and the cutting portion  4  is supported by the rocking shaft portions  35 A so that the cutting blade  7  is brought close to or separated from the upper surface of the turntable  22 . Therefore, the cutting portion  4  can reciprocate in the extending direction of the sliding pipes  33 . In addition, the sliding pipes  33  may be juxtaposed in the right-left direction, and the sliding pipes  33  are supported by the supporting portion  3  so as to be slidable back and forth. 
         [0038]    The cutting portion  4  is configured such that a housing  4 A journalled to the rocking shaft portion  35 A is used as an outer shell. As shown in  FIG. 2 , the housing  4 A mainly includes a motor housing portion  41 , a cutting blade housing portion  42 , a handle  43  used as a grip part during cutting, and a gear case  44 . As shown in  FIG. 3 , the motor housing portion  41  has a motor housing space  41   a  defined therein, and a motor  51  is built in the motor housing space  41   a . In the motor housing portion  41 , an air intake port  41   b  through which ambient air is allowed to flow into the motor housing space  41   a  is formed at a right end opposite to the cutting blade  7 , and an introduction passage  4   a  which communicates with the motor housing space  41   a , and also communicates with a cutting blade housing space  42   a  which will be described later is formed on the left on the side of the cutting blade  7 . 
         [0039]    A part which forms the introduction passage  4   a  of the motor housing portion  41  and communicates with the cutting blade housing space  42   a  which will be described later, as shown in  FIG. 4 , is provided with ribs  41 A which partition the introduction passage  4   a . By providing the ribs  41 A, the strength of the part which forms the introduction passage  4   a  of the motor housing portion  41  is kept. Additionally, an exhaust hole  4   b  which allows the motor housing space  41   a  and the ambient air to communicate with each other is formed in a position in the vicinity of the gear case  44  in the lower portion of the motor housing portion  41  which faces the timber W. 
         [0040]    As shown in  FIG. 3 , the motor  51  has a rotary shaft  51 A, is arranged within the motor housing space  41   a  and is fixed to the motor housing portion  41  so that the rotary shaft  51 A becomes parallel to the rotary shaft of the cutting blade  7 , and is located on the right side of the cutting blade  7 . A gap through which air can be blown in the right-left direction across the motor  51  is formed between the motor  51  and the motor housing portion  41  in a state where the motor  51  is housed within the motor housing space  41   a . A pinion gear  61  which constitutes a transmission mechanism  6  which will be described later is provided at the tip of the rotary shaft  51 A, and a fan  51 B is provided in a position which becomes a base portion of the pinion gear  61  of the rotary shaft  51 A so as to be rotatable with the rotary shaft  51 A. Since the fan  51 B is a centrifugal fan, the air volume of the fan can be made high compared with an axial fan. 
         [0041]    When the fan  51 B rotates by driving the motor  51 , vortex Fw which proceeds to the introduction passage  4   a  (the left of the fan  51 B) from the motor housing space  41   a  is generated. Therefore, negative pressure is formed on the right of the fan  51 B in the motor housing space  41   a . Ambient air is taken in from the air intake port  41   b  by this pressure difference, and this ambient air circulates through the motor housing space  41   a , and cools the motor  51 . The ambient air which has cooled the motor  51  flows into the introduction passage  4   a  beyond the fan  51 B. 
         [0042]    The direction in which the vortex Fw generated by the fan  51 B whirls becomes the same direction as the rotational direction of the fan  51 B. Additionally, since the exhaust hole  4   b  is formed in the left position of the fan  51 B, a portion of the vortex Fw generated by the fan  51 B is blown out from the exhaust hole  41   b.    
         [0043]    The cutting blade housing portion  42  has the cutting blade housing space  42   a  communicating with the introduction passage  4   a  formed therein, and a portion of the cutting blade  7  and a protective cover  4 C which protects the cutting blade  7  are configured within the cutting blade housing space  42   a  so as to be able to be housed. Therefore, the vortex Fw from the fan  51 B which has flowed into the introduction passage  4   a  is guided into the cutting blade housing space  42   a  after being corrected by the ribs  41 A ( FIG. 4 ). 
         [0044]    As shown in  FIG. 5 , a dust discharge passage  42   b  which extends upwards from a rear end position of the cutting blade  7  is formed behind the cutting blade housing portion  42 , a dust discharge port  42   c  is defined at the upper end of the dust discharge passage  42   b , and a garbage collection bag  8  ( FIG. 1 ) in which dusts are stored is attached to the portion of the dust discharge port  42   c . Additionally, a guide  42 A which is located on the right and left sides and on the rear side with respect to the rear end position of the cutting blade  7  is provided in the position of the cutting blade housing portion  42  which becomes a lower end of the dust discharge passage  42   b.    
         [0045]    The protective cover  4 C is mounted on the cutting blade housing portion  42  so as to be rotatable around the cutting blade  7  almost coaxially with the rotary shaft of the cutting blade  7 . Thus, when the cutting portion  4  ( FIG. 1 ) has rocked upwards, the protective cover covers the lower portion of the cutting blade  7 , and when the cutting portion  4  has rocked downwards, the protective cover is housed within the cutting blade housing space  42   a , and the lower portion of the cutting blade  7  is exposed. Additionally, a plurality of slits  4   c  is formed in a direction parallel to the rotational direction of the cutting blade  7  in the portion of the protective cover  4 C which faces the introduction passage  4   a.    
         [0046]    The handle  43 , as shown in  FIG. 2 , is arranged above the motor housing portion  41 , and as shown in  FIG. 7 , is provided with a trigger  43 A which controls the rotation of the motor  51  ( FIG. 3 ), and a power switch  43 B of a laser oscillator (not shown) which irradiates a part which becomes a cut position on the timber W with a laser beam or a light which illuminates the timber W. 
         [0047]    As shown in  FIG. 2 , the gear case  44  is located in the lower portion of the housing  4 A between the motor housing portion  41  and the cutting blade housing portion  42 , and as shown in  FIG. 6 , has a transmission mechanism  6  built therein. 
         [0048]    The transmission mechanism  6  mainly includes the aforementioned pinion gear  61  that is a first gear, an intermediate gear  62 , and a final gear  63 . The aforementioned pinion gear  61  is constituted by a helical gear, and is supported on the gear case  44  by the bearing  61 A. The intermediate gear  62  includes a second gear  62 A which meshes with a pinion gear  61 , a third gear  62 B which is arranged coaxially with the second gear  62 A, and meshes with the final gear  63 , and is rotatably supported on the gear case  44  by a pair of bearings  62 C and  62 D. Additionally, the second gear  62 A and the third gear  62 B are constituted by helical gears, respectively, and are configured so that the respective tooth trace directions are opposite to each other, and the number of teeth of the second gear  62 A becomes more than the number of teeth of the third gear  62 B. By this configuration, the number of rotations of the pinion gear  61  can be reduced and transmitted to the final gear  63 , and thrust directions can be configured so as to be cancelled by each other. The final gear  63 , which is a helical gear, meshes with the third gear  62 B, has a spindle  63 A mounted with the cutting blade  7 , and is rotatably supported on the gear case  44  by the pair of bearing  63 B and bearing  63 C. 
         [0049]    Since the final gear  63  is decelerated by the intermediate gear  62 , and its power is transmitted, it is not necessary to use a gear with too large a diameter in the pinion gear  61  to the final gear  63 . Therefore, the gear case  44  around the pinion gear  61  to the final gear  63  can be made small. By making the gear case  44  small, the gear case  44  is kept from abutting on the timber W when the cutting portion  4  is tilted. Additionally, a flange  64  and a bolt  64 C which fix the cutting blade  7  can be mounted on the spindle  63 A. 
         [0050]    The cutting blade  7  is fixed by the flange  64  and the bolt  64 C so as to be rotatable integrally and coaxially with the spindle  63 A, and is arranged so that its side surface becomes parallel to sliding direction of the cutting portion  4 , and is driven and rotated by the motor  51 . As for the rotational direction at this time, the cutting blade rotates so that the outer periphery of the cutting blade  7  moves downward from above on the plane of the paper of  FIG. 2  (clockwise on the plane of the paper of  FIG. 1 ). As the cutting blade  7  rotates, an airflow Sw ( FIG. 9 ) along the rotational direction of the cutting blade  7  is generated around cutting blade  7 . By the airflow Sw and the reaction at the time of the cutting of the timber W, as shown by an arrow T of  FIG. 5 , dusts are blown away and fed towards the guide  42 A, and are made to flow into a dust discharge passage  42   b , and dusts are stored within the garbage collection bag  8  ( FIG. 1 ) from the dust discharge port  42   c.    
         [0051]    Additionally, since the final gear  63  which is integral with the spindle  64 A to which the cutting blade  7  is fixed is connected with the pinion gear  61  via the intermediate gear  62 , the rotational direction of the final gear  63  and the rotational direction of the pinion gear  61  become the same direction. Therefore, the cutting blade  7  which rotates coaxially and integrally with the final gear  63 , and the fan  51 B which rotates coaxially and integrally with the pinion gear  61  rotate in the same direction. Since the rotational directions of the fan  51 B and the cutting blade  7  are the same direction, and the rotary shaft of the cutting blade  7  and the rotary shaft of the fan  51 B are parallel to each other, as shown in  FIG. 9 , the direction of the vortex Fw by the fan  51 B and the direction of the airflow Sw in the cutting blade  7  coincide with each other. 
         [0052]    When the bench cutting machine  1  of the above configuration cuts the timber W, as shown in  FIG. 7 , the timber W is placed on the base portion  2 , and the cutting portion  4  is made to slide on the sliding pipe  33 , and is made to move to the foremost side. If the trigger  43 A is pulled from this state, as shown in  FIG. 8 , the cutting portion  4  is rocked downward, and the cutting blade  7  is pushed against the timber W. Although the dusts of the timber W are generated at this time, as shown in  FIG. 9 , the dusts flow like the arrow T through the airflow Sw generated in the cutting blade  7 , and are stored in the garbage collection bag  8 . Additionally, although the vortex Fw generated by the fan  51 B passes through the introduction passage  4   a  and is introduced into the cutting blade housing space  42   a , since the whirling direction of the vortex Fw, and the direction of the airflow Sw are the same direction, the transfer of the dusts through the airflow Sw is not obstructed. On the contrary, the vortex Fw is added to the airflow Sw, so that dusts can be more properly transferred into the garbage collection bag  8 , and the derivation efficiency of the dusts can be enhanced. 
         [0053]    Since the airflow Sw and the vortex Fw, as shown in  FIG. 9 , flows towards the rear from the front on the surface of the timber W, dusts are kept from flowing towards the rear and flowing towards a user on the front of the bench cutting machine  1  around a cutting part of the timber W. Additionally, as shown in  FIG. 3 , although a portion of the vortex Fw is also blown out from the exhaust hole  4   b , the vortex Fw blown out from the exhaust hole  4   b  also similarly flows towards the rear from the front on the surface of the timber W, and flows towards the cutting blade  7  from the exhaust hole  4   b . Therefore, dusts which have deviated to the right from the vicinity of the cutting blade  7  are also blown away to the vicinity of the cutting blade  7  by the vortex Fw from the exhaust hole  4   b , are caught by the airflow Sw which flows through the vicinity of the cutting blade  7 , are transferred like the arrow T, and are stored by the garbage collection bag  8 . 
         [0054]    After the cutting portion  4  is rocked, the cutting portion  4  is made to slide on the sliding pipe  33 , and is made to move back, thereby ending the cutting of the timber W. Even when the cutting portion  4  moves back, as described above, dusts are blown away rearwards by the airflow Sw and the vortex Fw in the vicinity of the cutting blade  7 , and the vortex Fw which is blown out from the exhaust hole  4   b , the dusts do not flow towards the user (front), and cutting work can always be performed in a comfortable environment. 
         [0055]    In the embodiment, the cutting blade  7  is orthogonal to the upper surface of the base portion  2 . However, if the cutting portion  4  is tilted to the right and left, dusts can similarly be stored in the garbage collection bag  8 . Further in the bench cutting machine  101  in which the cutting portion  4  is directly and swingably mounted on the tilting portion  31 , as shown in  FIG. 11 , dusts can similarly be suitably stored in the garbage collection bag  8 . 
         [0056]    In the embodiment, the rotary shaft of the cutting blade  7  and the rotary shaft  51 A of the motor  51  are made parallel to each other, as shown in  FIG. 12 . However, the rotary shaft of the cutting blade  7 , and the rotary shaft  51 A of the motor  51  may intersect each other. In this case, since the direction of the vortex Fw coincides with the rotational direction of the cutting blade  7 , the airflow generated by the cutting blade  7  is not hindered by the vortex Fw. 
         [0057]    According to an aspect of the present invention, there is provided a bench cutting machine, in which the dusts during cutting can be more suitably discharged to the outside of the machine using the fan air. Additionally, since the transmission mechanism which makes the rotational directions of the fan and the saw blade the same is provided, a plurality of gears which constitute a transmission mechanism can be small, and when the cutting portion is rocked downward, the cutting portion is prevented from abutting on a descending member, so that the depth of cut-in can be enhanced. Since the cutting portion can be prevented from abutting on a descending member even when the cutting portion is inclined, the depth of cut-in during bevel cutting can be enhanced. 
         [0058]    This application claims priority from Japanese Patent Application No. 2008-253617 filed on Sep. 30, 2008, the entire contents of which are incorporated herein by reference. 
       INDUSTRIAL APPLICABILITY  
       [0059]    According to an aspect of the present invention, there is provide a bench cutting machine which more suitably discharges the dusts to the outside during cutting.