Patent Publication Number: US-2015059548-A1

Title: Cutting devices

Description:
This application claims priority to Japanese patent application serial number 2013-175435, the contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     Embodiments of the present invention relate to cutting devices such as table-type cutting devices and portable cutting devices. 
     2. Description of the Related Art 
     Typically, a table-type cutting device may have a table and a cutting unit movable relative to the table. The cutting unit may include a cutting blade such as a circular grinding wheel or a circular saw blade. The cutting unit may be moved downward relative to the table for performing a cutting operation of a workpiece supported on the table. In this specification, the term “cutting operation” may be used to define various operations. For example, one operation would be for separating a workpiece into two or more pieces. A second operation would be an operation for forming a groove into a workpiece without separating the workpiece. A third operation would be for trimming or grinding a workpiece. 
     There has been known a table-type cutting device that includes a table for supporting a workpiece, and a cutting unit having a circular rotary tool (such as a circular saw blade) which is vertically and laterally supported on the table. This type of cutting device may allow a normal vertical cutting operation, a miter cut operation or an inclined cutting operation. In the vertical cutting operation, the surface of the circular rotary tool extends vertically relative to the surface of the table. In a miter cut operation, a workpiece is cut obliquely from the edge thereof while the table is rotated by a given angle. In an inclined cutting operation, a workpiece is cut obliquely relative to a direction of thickness thereof while the cutting unit is inclined leftward or rightward from the vertical position. 
     US2009/0151529 discloses some techniques relating to a cutting device that can be used for performing both the miter cut operation and the inclined cut operation. According to the disclosed techniques, the rotary output of an electric motor as a drive source is reduced through a reduction gear train and is thereafter output to a spindle. Due to this arrangement, the electric motor can be located at a high position away from the spindle. In addition, the electric motor is oriented obliquely downward so as to be inclined relative to the axis of the spindle. In this way, the inclination angle of the cutting unit toward the right side (the side of the electric motor) can be set to a large value without causing interference with the workpiece. Because the cutting unit can be inclined to the right by a large inclination angle, it may be possible to increase possible variations in the cutting operation. 
     However, because the reduction gear train includes a gear mounted to the spindle, the size of the cutting device in the axial direction around the cutting blade is necessary to accommodate this arrangement. This leads to a limitation in the maximum incline angle. 
     Therefore, there has been a need in the art for reducing the size around the cutting blade of the cutting device in the axial direction of the cutting blade. 
     SUMMARY OF THE INVENTION 
     In one aspect according to the present teachings, a cutting device may include an electric motor, a cutting blade, a clamp device and a drive system. The clamp device may include a first flange and a second flange configured to clamp the cutting blade therebetween. The drive system may transmit rotation of the electric motor to the cutting blade via the first flange. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of a cutting device according to a representative embodiment; 
         FIG. 2  is a plan view of the cutting device as viewed in a direction indicated by arrow II in  FIG. 1 ; 
         FIG. 3  is a front view of the cutting device as viewed in a direction indicated by arrow III in  FIG. 1 ; and 
         FIG. 4  is a vertical sectional view of a part of a cutting unit of the cutting device showing a vertical sectional view of a drive system. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In one embodiment, a cutting device may include an electric motor, a cutting blade, a clamp device and a drive system. The clamp device may include a first flange and a second flange configured to clamp the cutting blade therebetween. The drive system may be configured to transmit rotation of the electric motor to the cutting blade and may include a belt transmission mechanism. The belt transmission mechanism may include a drive pulley, a driven pulley and a belt extending between the drive pulley and the driven pulley. The driven pulley may be coupled to the first flange of the clamp device. 
     With this arrangement, because the rotation of the electric motor may be transmitted to the cutting blade via the first flange of the clamp device, it is not necessary to provide a gear or the like separately from the clamp device for transmitting rotation to the cutting blade. Therefore, it is possible to eliminate space necessary for a separate gear or the like. As a result, it is possible to reduce the space occupied by the drive system around the cutting blade. 
     In addition, because the belt transmission mechanism is used for transmitting rotation to the first flange of the clamp device, it is possible to increase the distance between the axis of the electric motor and the axis of the cutting blade. Therefore, in particular when the cutting device has a table or a base for placing a workpiece thereon and that the cutting blade is tiltable relative to the table or the base, it is possible to increase the maximum tiltable angle of the cutting blade. 
     The driven pulley may be integrated with the first flange. For example, the driven pulley may be formed integrally with the first flange. With this construction, the drive system may be simplified. 
     The cutting device may further include a drive housing and a spindle rotatably supported within the drive housing via a bearing. The cutting blade may be mounted to the spindle while the cutting blade being clamped between the first flange and the second flange. The bearing may be disposed within the drive housing such that the bearing overlaps the first flange with respect to an axial direction of the spindle. 
     With this arrangement, it is possible to reduce the axial length of the drive system including the spindle around the cutting blade. 
     The cutting device may further include a spindle lock mechanism configured to lock the rotation of the spindle. The spindle lock mechanism may include a lock member and a rotational member that rotates with the spindle. The lock member may be configured to engage the rotational member. Locking the spindle by the spindle lock mechanism may facilitate the clamping and unclamping operation of the clamp device, so that the cutting blade can be rapidly mounted and removed. 
     A representative embodiment will now be described with reference to  FIGS. 1 to 4 . Referring to  FIG. 1 , there is shown a cutting device  1  according to the representative embodiment. In order to operate the cutting tool  1 , the user may be positioned on the right side as viewed in  FIG. 1  of the cutting device  1 . In the following description, a front side, a rear side, a left side, a right side, an upper side and a lower side are determined with reference to the position of the user who is positioned for operating the cutting device  1 . Therefore, the user may be positioned on the front side of the cutting device  1  for operating the same. The user may perform a cutting operation of a workpiece W by moving a cutting unit  10  of the cutting device  1  in a direction from the side of the user toward the rear side. 
     The cutting device  1  may be a so-called slide-type miter saw and may include a table  2 , on which the workpiece W can be placed, and a base  3  supporting the table  2 . The cutting unit  10  may be supported on the upper side of the table  2  and may be operable to move vertically relative to the table  2 . The table  2  may be supported on the upper surface of the base  3  so as to be rotatable within a horizontal plane. A pair of auxiliary tables  3   a  may be disposed on the left and right sides of the base  3 . Each of the auxiliary tables  3   a  may have an upper surface that extends within a same plane as the upper surface of the table  2 . The workpiece W may be placed on the table  2  such that the workpiece W extends between the auxiliary tables  3   a . The workpiece W may be fixed in position relative to the pair of auxiliary tables  3   a  by suitable clamp devices (not shown). A fence  4  may be positioned on the upper side of the table  2  for positioning the workpiece W. The fence  4  may extend between the auxiliary tables  3   a  while being spaced from the upper surface of the table  2  by a little distance. The fence  4  may have a positioning surface for contacting the workpiece W. The positioning surface may extend along a plane that passes through the rotational axis of the table  2  as viewed from the upper side. 
     A grip  2   a  may be provided on the front portion of the table  2 . Therefore, the user can rotate the table  2  clockwise or counterclockwise by grasping the grip  2   a . The rotational position of the table  2  can be locked by inserting a front end of a positioning rod  2   b  into any one of the positioning grooves  3   b  formed in the base  3 . An unlock lever  2   c  may be vertically pivotally mounted to the table  2  at a position on the upper side of the grip  2   a . Pivoting the unlock lever  2   c  downward can retract the positioning rod  3   b  forward to release the locked state of the table  2 . In this released state, the table  2  can be rotated. The rotational position can be also locked by tightening the unlock lever  2   c  that may be threadable engaged with the table  2 . 
     The cutting unit  10  may be supported by the table  2  via upper and lower slide mechanisms, so that the cutting unit  10  can slidably move in the forward and rearward directions. 
     More specifically, the rear portion of the table  2  may support a unit support  6  via the lower slide mechanism. The lower slide mechanism may include a pair of right and left slide bars  5  that are supported by corresponding bearings (not shown) so as to be slidably movable in the forward and rearward directions. The slide bars  5  can be fixed at a desired position by tightening a fixing screw  5   a.    
     The unit support  6  may include a first tilt support device  7  and a unit support arm  8 . The first tilt support device  7  may be connected to the rear portions of the pair of right and left slide bars  5 . The first tilt support device  7  may allow the cutting unit  10  to be tilted leftward or rightward as viewed from the side of the user (leftward or rightward in  FIG. 3 ), so that an inclined cutting operation can be performed. The first tilt support device  7  may include a support member  7   a  and a tiltable member  7   b  that are rotatably coupled to each other via a tilt shaft (not shown). The tilt shaft may extend in the forward and rearward directions within the same plane as the upper surface of the table  2  as viewed from the lateral side. The support member  7   a  may be joined to the rear portions of the pair of right and left slide bars  5 . The unit support arm  8  may extend upward from the upper portion of the unit support member  7   b . The first tilt support device  7  may allow the tool unit  10  to be positioned at a vertical position or at a left or right tilt position, such as a left 45° tilt position. In the vertical position, a surface of a cutting blade  21  of the tool unit  10  may extend vertically relative to the upper surface of the table  2 . In the left or right tilt position, the cutting blade  21  may be inclined leftward or rightward from the vertical position. With the tool unit  10  positioned at the vertical position, a vertical cutting operation can be performed. With the tool unit  10  positioned at the right or left tilt position, an inclined cutting operation can be performed. The tool unit  10  may be fixed at the vertical position or the right or left tilt position by tightening a fixing lever  7   c.    
     The upper slide mechanism may include a pair of slide bars  11  connected to the upper portion of the unit support arm  7   b . More specifically, a slide bar holder  9  may be provided at the upper portion of the unit support arm  7   b . The rear portions of the pair of slider bars  11  may be fixedly connected to the slide bar holder  9 , so that the pair of slider bars  11  extend forward from the slide bar holder  9 . The pair of slide bars  11  may extend parallel to each other and spaced from each other in the vertical direction. The front portions of the pair of slider bars  11  may be fixedly connected to each other via a connecting member  12 . 
     A slider  13  may be supported on the pair of slide bars  11 , so that the slider  13  can slide in the forward and rearward directions along the pair of slider bars  11  within a range between the slide bar holder  9  and the connecting member  12 . 
     The tool unit  10  may be supported on the right side portion of the slider  13 . More specifically, the tool unit  10  may be supported by the slider  13  via a second tilt support device  14 , so that the tool unit  10  can tilt vertically relative to the slider  13 . The tool unit  10  having the cutting blade  12  may include a unit case  15  and an electric motor  16 . The unit case  15  may be vertically pivotally supported by the front side portion of the slider  13  via a tilt shaft  14   a  of the second tilt support device  14 . The electric motor  16  may be mounted to the right side portion of the unit case  15 . The cutting blade  12  may have a circular shape and may be rotatably driven by the electric motor  16 . The upper portion of the cutting blade  12  may be covered by the unit case  15 . A movable cover  17  may be opened and closed for uncovering and covering the lower portion of the cutting blade  12 . The movable cover  17  may be coupled to a link arm  17   a  connected between the second tilt support device  14  and the unit case  15 , so that the movable cover  17  can open and close in response to the vertical tilting movement of the cutting unit  10 . When the cutting unit  10  is positioned at an uppermost position shown in  FIG. 1 , the movable cover  17  may be completely closed to cover the lower portion of the cutting blade  12 . In this way, the unit case  15  and the movable cover  17  may cover the entire cutting blade  12 . As the cutting unit  10  moves downward from the uppermost position, the movable cover  17  may pivot in a clockwise direction as viewed in  FIG. 1 , so that the movable cover  17  is opened. When the cutting unit  10  reaches a lowermost position, the movable cover  17  is completely opened and the uncovered lower portion of the cutting blade  21  may cut into the workpiece W. 
     As shown in  FIG. 4 . a motor base  22  may be formed integrally with the right upper portion of the unit case  15 . The electric motor  26  may be mounted to the motor base  22 . The unit case  15  may include a main handle  18  and a sub handle  19  (see  FIG. 1 ) located on the upper side of the electric motor  26  so as to straddle between the front portion and the rear portion of the motor base  22 . Each of the main handle  18  and the sub handle  19  may be elongated in the forward and rearward directions. The sub handle  19  may be positioned on the rear side of the main handle  18 . 
     The user may grasp the main handle  18  for vertically tilting the cutting unit  10 . A switch lever  18   a  for starting and stopping the electric motor  16  may be positioned at the lower surface of the main handle  18 . Therefore, the user who grasps the main handle  18  can pull the switch lever  18   a  by using fingers of the same hand that grasps the main handle  18 . Pulling the switch lever  18   a  can start the electric motor  16 , so that the cutting blade  21  rotates in the clockwise direction as viewed in  FIG. 1 . 
     The sub handle  19  may be positioned such that it extends substantially in the horizontal direction when the cutting unit  10  is positioned at the lowermost position. Although not shown in the drawings, a stopper device may be provided for fixing the cutting unit  10  at the lowermost position. With the cutting unit  10  fixed at the lowermost position, the user can carry the cutting device  1  by grasp the sub handle  19 . In this way, the sub handle  19  can be used as a carrying handle. 
     The cutting unit  10  may further include a lightning device  20  that extends upward from a position between the main handle  18  and a sub handle  19 . When the lightning device  10  is turned on, the light may be emitted to largely illuminate a region where the cutting blade  12  cuts the workpiece W, so that operations in a dark place can be facilitated. 
     A drive system  30  of the cutting unit  10  will now be described with reference to  FIG. 4 . The drive system  30  may transmit the rotation of the electric motor  16  to a spindle  32  to which the cutting blade  21  is attached. In this embodiment, the drive system  30  may include a belt transmission mechanism  40 . 
     A drive housing  31  may be formed integrally with the motor base  22  so as to extend downward therefrom. A housing cover  23  may be positioned on the left side of the drive housing  31  so as to be opposed thereto. The drive system  30  may be disposed within a space defined between the drive housing  31  and the housing cover  23  and along the left side surface of the housing cover  23 . 
     A drive gear  16   a  may be formed on an output shaft of the electric motor  16  and may engage an intermediate gear  34 . The intermediate gear  34  may be a bevel gear. Therefore, the electric motor  16  may be mounted to the motor base  22  such that the output shaft is inclined downward with the right side portion of the electric motor  16  located upward of the left side portion. 
     The intermediate gear  34  may be mounted to a right side portion of an intermediate shaft  35 . The intermediate shaft  35  may be rotatably supported by the drive housing  31  via left and right bearings  36  and  37 . The left bearing  36  may be supported within a cylindrical tubular bearing holder  23   b  formed on the upper portion of the right side surface of the housing cover  23 . A thrust bearing  38  may be mounted to the intermediate shaft  35  in order to bear against a thrust load that may be applied to the intermediate gear  34  in the right direction. 
     The left end of the intermediate shaft  35  may extend through the housing cover  23  to protrude into the unit case  15 . A drive pulley  41  of the belt transmission mechanism  40  may be mounted to the protruding end of the intermediate shaft  35 . The drive pulley  41  may be secured to the protruding end of the intermediate shaft  35  by a fixing screw  46  that is threadably engaged with the end surface of the protruding end. In this way, the drive pulley  41  may rotate together with the intermediate shaft  35 . The drive pulley  41  may be disposed within a pulley accommodating portion  23   c  of the housing cover  23 . The pulley accommodating portion  23   c  may have a substantially semicircular shape and may be provided on the upper portion of the left side surface of the hosing cover  23 . A dust-preventing pulley cover  23   d  may be attached to the pulley accommodating portion  23   c , so that the space within the pulley accommodating portion  23   c  can be shielded from within the case body  15 . 
     The lower portion of the drive housing  31  may rotatably support the spindle  32  via left and right bearings  33  and  39 . The left bearing  33  (on the side of the front end of the spindle  32 ) may be mounted within a cylindrical tubular bearing holder  23   a  provided on the housing cover  23 . The bearing holder  23   a  may protrude toward the side of the unit case  15  (i.e. leftward). The left end portion of the spindle  32  may protrude into the unit case  15  through the bottom portion (left side portion) of the bearing holder  23   a . The cutting blade  21  may be mounted to the protruding end of the spindle  32 . More specifically, the cutting blade  21  may be fixed in position relative to the spindle  32  by a clamp device including a disk-shaped outer flange  42  and a disk-shaped inner flange  43  that clamp the cutting blade  21  therebetween. The outer flange  42  may be fixed to the spindle  32  by means of a fixing screw  44  that is threadably engaged with the front end of the spindle  32 . The inner flange  43  may be interposed between the cutting blade  21  and a flange portion  32   a  formed on the spindle  32 . The front end portion of the spindle  32  may have a non-circular cross-section. The outer flange  42  and the inner flange  43  may have insertion holes having non-circular shapes conforming to the non-circular sectional shape of the front end portion of the spindle  32 . The front end portion of the spindle  32  may be inserted into the insertion holes of the outer flange  42  and the inner flange  43 , so that the outer flange  42  and the inner flange  43  may be prevented from rotating relative to the spindle  32 . For example, the non-circular cross sectional shape of the front end portion of the spindle  32  may be a shape corresponding to a circular shape with opposite sides cut to form parallel linear edges. Therefore, by tightening the fixing screw  44 , the cutting blade  21  may be firmly clamped between the outer flange  42  and the inner flange  43 . As a result, the cutting blade  21  can be firmly fixed to the spindle  32 . 
     A cylindrical tubular driven pulley  43   a  may be formed integrally with the right side portion of the inner flange  43 . As shown in  FIG. 4 , the bearing holder  23   a  of the housing cover  23  may be positioned on the radially inner side of the driven pulley  43   a . Therefore, the left bearing  33  rotatably supporting the spindle  32  may be also positioned on the radially inner side of the driven pulley  43   a . In this way, the left bearing  33  overlaps the inner flange  43  with respect to the axial direction of the spindle  32  (the left and right directions as viewed in  FIG. 4 ). 
     A suitable clearance may be provided between the inner circumferential surface of the driven pulley  43   a  and the outer circumferential surface of the bearing holder  23   a . In this way, the driven pulley  43   a  and the bearing holder  23   a  do not interact with each other. Therefore, the driven pulley  43   a  may rotate together with the spindle  32  on the radially outer side of the bearing holder  23   a.    
     The driven pulley  43   a  may serve as a driven pulley for the belt transmission mechanism  40 . A transmission belt  45  is engaged with the driven pulley  43   a  and the drive pulley  41  so as to extend therebetween. 
     With the above construction, the rotation of the electric motor  16  may be transmitted to the intermediate shaft  35  through engagement between the drive gear  16   a  and the intermediate gear  34 . The rotation of the intermediate shaft  35  may be further transmitted to the inner flange  43  via the belt transmission mechanism  40  that includes the drive pulley  41 , the driven pulley  43   a , and the transmission belt  45 . The rotation of the inner flange  43  may be further transmitted to the cutting blade  21  via the spindle  32 . 
     In this embodiment, the drive system  30  may further include a spindle lock mechanism  50 . The spindle lock mechanism  50  may include a lock member  51  and a rotational member  52  cooperating with the lock member  51 . The lock member  51  may be mounted within the drive housing  31  so as to be movable in an axial direction (the left and right directions in  FIG. 4 ) relative to the drive housing  31 . A compression spring  53  may bias the lock member  51  in an unlock direction (rightward in  FIG. 4 ). The rotational member  52  may have a thin disk-like shape and may be fixedly mounted to the spindle  32  so as to rotate together with the spindle  32 . A plurality of engaging recesses  52   a  may be fainted in the outer circumferential edge of the rotational member  52  for engagement with the lock member  51 . 
     Therefore, when the user pushes the lock member  51  in a lock direction which is against the biasing force of the spring  53 , the left end portion of the lock member  51  may engage any one of the engaging recesses  52   a  of the lock members  52 . In this way, the rotation of the rotational member  52   a  and eventually the rotation of the spindle  32  can be locked. Releasing the pushing force applied to the lock member  51  may cause the lock member  51  to move in the unlock direction. 
     With the spindle  32  locked by the spindle lock mechanism, the fixing screw  44  can rotate easily in the tightening direction and in the loosening direction. In this way, the operation for mounting the cutting blade  21  to the spindle  32  and removing the cutting blade  21  from the spindle  32  can be easily and rapidly performed. 
     As described above, according to the representative embodiment, the drive system  30  is configured such that the rotation of the electric motor  16  is transmitted to the cutting blade  21  through engagement between the drive gear  16   a  and the intermediate gear  34  and further through the belt transmission mechanism  40 . In this way, no gear is necessary to be provided on the spindle  32 , so that an accommodation space for the drive system  30  can be minimized with respect to the axial direction of the spindle  32 . This may allow the right side portion of the drive housing  32  to be shifted to the right as compared to the position in the case of the prior art. This is indicated by the difference between the two-dot chain lines and the solid lines in  FIG. 4 . 
     In addition, the left bearing  33  rotatably supporting the spindle  32  is positioned on the radially inner side of the driven pulley  43   a  of the inner flange  43 . It overlaps with the driven pulley  43   a  with respect to the axial direction of the spindle  32  (the left and right directions as viewed in  FIG. 4 ). Therefore, also in this respect, an accommodation space for the drive system  30  can be minimized with respect to the axial direction of the spindle  32 . 
     By providing no gear on the spindle  32  and by positioning the left bearing  33  so as to overlap with the driven pulley  43   a , it may be possible to shift the right side portion of the drive housing  31 , in particular the right end surface of lower portion of the drive housing  31 , can be shifted leftward from the position indicated by the two-dot chain lines to the position indicated by the solid lines in  FIG. 4 . Therefore, it is possible to determine a right side maximum inclination angle of the cutting unit  10  to be larger than in the known art. This also means that it is possible to perform an inclined cutting operation of a workpiece that that has a higher height than available in the known art. 
     The above representative embodiment may be modified in various ways. For example, although the left bearing  33  rotatably supporting the spindle  32  is positioned on the radially inner side of the driven pulley  43   a  so as to overlap therewith with respect to the axial direction of the spindle  32  in the above representative embodiment, this overlapping arrangement may be omitted. Thus, the position of the left bearing  33  may be shifted rightward from the position shown in  FIG. 4  so as not to overlap with the driven pulley  43   a . Also with this arrangement, as no gear provided on the spindle  32 , it is possible to minimize the accommodation space for the drive system  30 . 
     Although the rotational member  52  of the spindle lock device  50  is mounted on the spindle  32  for locking the rotation of the spindle  32 , the rotational member  52  can be mounted to any other member than the spindle  32 . For example, the rotational member  52  may be mounted to the intermediate shaft  35 , so that the rotation of the spindle  32  can be indirectly locked. 
     Further, a bearing (not shown) may be interposed between the driven pulley  43   a  and the bearing holder  23   a  of the housing cover  23  such that the driven pulley  43   a  is rotatably supported by the bearing holder  23   a . In such a case, the spindle  32  may be formed integrally with the driven pulley  43   a , and the left and right bearings  33  and  39  can be omitted. With this arrangement, the position of the right side portion of the drive housing  31  may be shifted further leftward to enable a right side maximum inclination angle of the cutting unit  10  to be further increased. 
     Furthermore, although the cutting device  1  is configured as a table-type cutting device in the above representative embodiment, the present teachings can be also applied to a drive system of a portable circular saw. The portable circular saw may have a base for contacting an upper surface of a workpiece, and a cutting unit that includes a circular saw blade protruding downward through the base for cutting the workpiece during a cutting operation. 
     Representative, non-limiting examples of the present invention were described above in detail with reference to the attached drawings. This detailed description is merely intended to teach a person of skill in the art further details for practicing preferred aspects of the present teachings and is not intended to limit the scope of the invention. Furthermore, each of the additional features and teachings disclosed above may be utilized separately or in conjunction with other features and teachings to provide improved battery packs, and methods of making and using the same. 
     Moreover, combinations of features and steps disclosed in the above detailed description may not be necessary to practice the invention in the broadest sense, and are instead taught merely to particularly describe representative examples of the invention. Furthermore, various features of the above-described representative examples, as well as the various independent and dependent claims below, may be combined in ways that are not specifically and explicitly enumerated in order to provide additional useful embodiments of the present teachings. 
     All features disclosed in the description and/or the claims are intended to be disclosed separately and independently from each other for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter, independent of the compositions of the features in the embodiments and/or the claims. In addition, all value ranges or indications of groups of entities are intended to disclose every possible intermediate value or intermediate entity for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter.