Abstract:
A rotary cutting machine  10,  if inclined at large angles, provides positive supply of a cutting oil and avoids leakage of the cutting oil. The machine  10  has a machine body  14  and an arbor  18.  An oil tank  50  is mountable to the machine body  14  so that the oil tank  50  is oriented at a given angular position about the central axis of the arbor  18.  The tank body  54  has an interior space. The interior space is divided into a first interior part and a second interior part by an imaginary plane containing the central axis of rotation of the arbor. The first interior part is less in volume than the second interior part.

Description:
RELATED APPLICATIONS 
       [0001]    This application is a continuation application of U.S. application Ser. No. 10/570 391 filed on Mar. 1, 2006, which claims priority to Japanese Patent Application Nos. JP2004-209624 filed on Jul. 16, 2004 and JP2004-229766 filed on Aug. 5, 2004, the contents of which are hereby incorporated by references entirely. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to rotary cutting machines such as power driven drills and more particularly, to a rotary cutting machine furnished with a device for feeding a cutting oil to a rotary cutting tool. 
       BACKGROUND OF THE INVENTION 
       [0003]    A rotary cutting machine particularly designed for on-site use rather than for factory use is, in some cases, inclined to accommodate various orientations of workpieces. Typically, this type of rotary cutting machine is provided with an oil reservoir within which cutting oil is contained. The oil reservoir has a vent hole positioned above the level of the cutting oil and communicated with ambient air (see, for example, Japanese utility model application publication No. 3-15009). To smoothly feed the cutting oil, the level of the cutting oil within the oil reservoir is made higher than the level at which the cutting oil is fed to a cutting tool. 
         [0004]    To facilitate on-site use, there is a need for a compact and lightweight rotary cutting machine which allows a cutting tool to have a sufficient degree of cutting stroke. Various attempts have been made to meet these needs. See, for example, Japanese patent application publication Nos. 2002-538976 and 2005-22055. 
         [0005]    It is an object of the present invention to provide a rotary cutting machine which can smoothly feed a cutting oil to a cutting tool without leakage, in the event that the rotary cutting machine is inclined at a relatively large angle so that the machine is properly placed against a workpiece, and which is compact and lightweight and allows the cutting tool to have a sufficient degree of cutting stoke. 
       SUMMARY OF THE INVENTION 
       [0006]    According to one aspect of the present invention, there is provided a rotary cutting machine comprised of a machine body including a rotatable arbor adapted to hold a rotary cutting tool which is rotated with the arbor about the central axis of rotation of the arbor, an oil tank adapted to feed a cutting oil to the rotary cutting tool and mounted to the machine body with the oil tank being oriented in a given angular position about the central axis of rotation of the arbor wherein the arbor includes an inlet port for receiving the cutting oil from the oil tank, an outlet port for directing the cutting oil to the rotary cutting tool, and an oil line axially extending from the inlet port to the outlet port, wherein the oil tank has an interior space divided into a first interior part and a second interior part by an imaginary plane containing the central axis of rotation of the arbor, with the first interior part being less in volume than the second interior part. 
         [0007]    When the rotary cutting machine is inclined, the orientation of the oil tank is adjusted so that the first interior part of a relatively small volume is located below the second interior part of a relatively large volume. This configuration makes it possible to raise, in a relative sense, the level of the cutting oil within the oil tank and thus, ensures positive supply of the cutting oil to the rotary cutting tool when the machine body is inclined at a relatively large angle. 
         [0008]    In one embodiment, the oil tank includes a tank body configured to sealingly contain the cutting oil and including an oil outlet communicated with the inlet port of the arbor, a float, and a flexible vent pipe mounted within the oil tank. The vent pipe has one end communicated with ambient atmosphere outside of the oil tank and the other end to which the float is connected. The float allows the other end of the vent pipe to be located above the level of the cutting oil within the tank body. 
         [0009]    This arrangement avoids leakage of the cutting oil from the oil tank regardless of the angle of inclination of the machine body. 
         [0010]    In another embodiment, the machine body includes a housing surrounding the arbor and including a cylindrical oil tank mount extending outwardly from the housing and disposed in a coaxial relation to the arbor. The oil tank mount has a through cavity communicated with the inlet port of the arbor. The oil tank includes a joint secured to the oil tank mount and having a split clamping ring disposed around the oil tank mount and a fastener for securing the clamping ring to the oil tank mount. 
         [0011]    This arrangement allows the oil tank to be oriented in the desired angular position about the central axis of rotation of the arbor when or after the oil tank is mounted to the machine body. 
         [0012]    Optionally, a hose fitting may be mounted to the oil tank mount when the oil tank is not in use. The hose fitting may be in the form of a cap fitted over the oil tank mount and including an outwardly extending connecting pipe adapted for connection with an external oil hose so that an cutting oil can be fed from the oil hose to the through cavity of the oil tank mount. 
         [0013]    The cutting oil can not be fed to the cutting tool if the machine body is unduly inclined (for example, placed upside down). To this end, an external hose is connected to the hose fitting to feed a cutting oil to the cutting tool. 
         [0014]    In a preferred embodiment, the tank body has a bottom wall mounted to the machine body and having a peripheral edge, a peripheral wall extending from the peripheral edge of the bottom wall in a direction away from the machine body and a top wall attached to the peripheral wall and spaced a predetermined distance from the bottom wall. The oil outlet is disposed in the bottom wall adjacent to a part of the peripheral wall of the tank body where the first interior part is located. 
         [0015]    According to another aspect of the present invention, there is provided a rotary cutting machine comprised of a machine body including a rotatable arbor and adapted to hold a rotary cutting tool which is rotated with the arbor about the central axis of rotation of the arbor, and an oil tank mounted to the machine body and adapted to feed a cutting oil to the rotary cutting tool, wherein the arbor includes an inlet port for receiving the cutting oil from the oil tank, an outlet port for directing the cutting oil to the rotary cutting tool, and an oil line axially extending from the inlet port to the outlet port, and wherein the oil tank includes a tank body configured to sealingly contain the cutting oil and including an oil outlet communicated with the inlet port of the arbor, a float and a flexible vent pipe mounted within the tank body and having one end communicated with ambient atmosphere outside of the oil tank. The float is connected to the other end of the vent pipe to allow the other end of the vent pipe to be located above the level of the cutting oil within the tank body. 
         [0016]    Advantageously, the rotary cutting machine avoids leakage of the cutting oil from the oil tank regardless of the angle of inclination of the machine during a cutting process. The tank body may therefore be made to be mountable to the machine body so that the tank body is oriented in a given angular position relative to the machine body, in particular, about the central axis of rotation of the arbor. 
         [0017]    In one embodiment, the arbor includes a proximal rotary shaft mounted to the machine body for rotation about the central axis of rotation and drivingly connected to a motor, an intermediate rotary shaft telescopically connected to the proximal rotary shaft and movable between an extended position wherein the proximal rotary shaft and the intermediate rotary shaft are axially overlapped with one another by a relatively short axial length and a retracted position wherein the proximal rotary shaft and the intermediate rotary shaft are axially overlapped with one another by a relatively long axial length, the intermediate rotary shaft being rotated with the proximal rotary shaft, a distal rotary shaft telescopically connected to the intermediate rotary shaft and moved between an extended position wherein the intermediate rotary shaft and the distal rotary shaft are axially overlapped with one another by a relatively short axial length and a retracted position wherein the intermediate rotary shaft and the distal rotary shaft are axially overlapped with one another by a relatively long axial length, and rotated with the intermediate rotary shaft, the rotary cutting tool being secured to the leading end of the distal rotary shaft, a cylindrical holder configured to rotatably support the distal rotary shaft and mounted to the machine body so that the cylindrical holder is axially movable with the distal rotary shaft, and a cylindrical guide axially movably mounted to the machine body and adapted to axially movably hold and rotationally secure the cylindrical holder. The rotary cutting machine also includes a feed mechanism which includes a first pinion rotatably mounted to the machine body, a first rack formed on the outer peripheral surface of the cylindrical holder and extending parallel to the central axis of rotation, a second rack formed on the outer peripheral surface of the cylindrical guide, disposed in parallel relation to the central axis of rotation and meshed with the first pinion, a third rack formed on the machine body and extending parallel to the first rack, and a second pinion rotatably mounted to the cylindrical guide and meshed with the first and third racks. The cylindrical guide is axially displaced upon rotation of the first pinion to cause the second pinion to be moved along the third rock so that by way of the first rack, the distal rotary shaft and the intermediate rotary shaft are moved between the respective extended and retracted positions. The motor includes an output shaft which extends perpendicular to the central axis of rotation of the arbor. 
         [0018]    In this way, the rotary cutting machine of the present invention can be brought into a compact arrangement when the machine is not in use. Also, the rotary cutting machine can have a sufficient degree of cutting stoke during a cutting operation. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0019]      FIG. 1  is a side elevation, in section, of a rotary cutting machine according to the present invention; 
           [0020]      FIG. 2  is a front view of the rotary cutting machine; 
           [0021]      FIG. 3  is an enlarged side elevation, in section, of an arbor incorporated in the rotary cutting machine; 
           [0022]      FIG. 4  is a vertical section view of the arbor in its extended position; 
           [0023]      FIG. 5  is a plan view, partly in section, showing an oil tank mount formed on the machine body; 
           [0024]      FIG. 6  is a side view of the rotary cutting machine as rotated from a horizontal orientation shown in  FIG. 1  to a vertical orientation; and 
           [0025]      FIG. 7  shows the manner in which a hose fitting is mounted to the oil tank mount of the machine body after an oil tank is removed. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0026]    The present invention will now be described with reference to the accompanying drawings. 
         [0027]      FIG. 1  is a side elevation, in section, of a rotary cutting machine (in the illustrated embodiment, in the form of a power driven drill) assembled according to the present invention.  FIG. 2  is a front view of the rotary cutting machine. As shown, the rotary cutting machine  10  includes a machine body  14  to which a motor  12  with an output shaft  12   a  is mounted, an arbor  18  (for rotating a cutting tool) drivingly connected to the output shaft  12   a  of the motor  12  through a gear train  17  with a bevel gear  17   a,  a feed mechanism  20  for reciprocatingly moving a cutting tool C (illustratively, in the form of an annular cutter) to and from a workpiece W (in the embodiment shown in  FIGS. 1 and 2 , made, for example, of steel and horizontally placed below the power driven drill), and an electromagnetic base  41  attached to the lower end of the machine body and adapted to secure the machine body  14  to the workpiece. The rotary cutting tool C is secured to the lower end of the arbor  18 . A grip  42  is arranged on the upper section of the machine body  14 . 
         [0028]    As shown better in  FIGS. 3 and 4 , the arbor  18  includes a proximal rotary shaft  22  mounted to the machine body  14  for rotation about its vertical central axis and drivingly connected to the motor  12  through the gear train  17 , an intermediate rotary shaft  24  telescopically and splinedly connected to the proximal rotary shaft  22 , moved between an extended position (see  FIG. 4 ) wherein the proximal rotary shaft  22  and the intermediate rotary shaft  24  are axially overlapped with one another by a relatively short axial length and a retracted position (see  FIGS. 1 and 3 ) wherein the proximal rotary shaft  22  and the intermediate rotary shaft  24  are axially overlapped with one another by a relatively long axial length, and rotated with the proximal rotary shaft  22 , a distal rotary shaft  26  telescopically and splinedly connected to the intermediate rotary shaft  24  moved between an extended position (see  FIG. 4 ) wherein the intermediate rotary shaft  24  and the distal rotary shaft  26  are axially overlapped with one another by a relatively short axial length and a retracted position (see  FIGS. 1 and 3 ) wherein the intermediate rotary shaft  24  and the distal rotary shaft  26  are axially overlapped with one another by a relatively long axial length, and rotated with the intermediate rotary shaft  24 , a cylindrical holder  28  adapted to rotatably support the distal rotary shaft  26  through a needle bearing  27  and mounted to the machine body for axial movement with the distal rotary shaft  26 , and a cylindrical guide  29  axially displaceable within a cylindrical portion  14   a  of the machine body  14  disposed in a coaxial relation to the arbor  18  and adapted to axially move and rotationally secure the cylindrical holder  28 . A plurality of locking balls  26   a  are arranged on the lower end of the distal rotary shaft  26  to hold the annular cutter C in place. A sleeve  26   b  extends around the lower end of the distal rotary shaft  26 . Specifically, the sleeve  26   b  is rotatable between a locking position (as shown in  FIGS. 1 and 3 ) wherein the locking balls  26   a  are received in a recess, which is formed in a part of the annular cutter C inserted within the distal rotary shaft  26 , to lock the annular cutter C in position and an unlocking position wherein the locking balls  26   a  are radially outwardly moved and disengaged from the recess. 
         [0029]    The feed mechanism  20  includes a straight first rack  30  formed on the outer peripheral surface of the cylindrical holder  28  and extending parallel to the central axis of the arbor  18 , a second rack  31  formed on the outer peripheral surface of the cylindrical guide  29  and extending parallel to the first rack  30 , a third rack  32  formed on the inner peripheral surface of the (stationary) cylindrical portion  14   a  of the machine body and extending parallel to the first and second racks, a first pinion  33  rotatably mounted to the machine body and meshed with the second rack  31 , and a second pinion  34  rotatably mounted to the cylindrical guide  29  and meshed with the first rack  30  and the third rack  32 . 
         [0030]    When the rotary cutting machine is not in use, the arbor  18  is held in its retracted position as shown in  FIGS. 1 and 3 . To cut a hole in the workpiece, the motor  12  is energized to rotate the distal rotary shaft  26  through the proximal rotary shaft  22  and the intermediate rotary shaft  24 . The annular cutter C is rotated with the distal rotary shaft  26 . The first pinion  33  is then rotated (in a counterclockwise direction in  FIG. 4 ) by means of an operating lever  35  which is in turn, secured to one end of the shaft of the first pinion  33  outside of the machine body  14 . This rotation causes downward movement of the cylindrical guide  29 . At this time, the second pinion  34  is downwardly moved on and along the third rack  32  while the second pinion  34  is rotated in a clockwise direction. This causes the cylindrical holder  28  to be downwardly moved with the distal rotary shaft  26 . It will be noted that the distance of downward movement of the distal rotary shaft  26  is twice as long as the distance of downward movement of the cylindrical guide  29 . When the distal rotary shaft  26  reaches the lower end of the intermediate rotary shaft  24 , the distal rotary shaft  26  is brought into interlocking engagement with a stopper which is disposed on the lower end of the intermediate rotary shaft  24 . As a result of this engagement, the intermediate rotary shaft  24  is forced to be downwardly moved with the distal rotary shaft  26 . 
         [0031]      FIG. 4  shows the manner in which the distal rotary shaft  26  is moved to its lowest position. With the distal rotary shaft in its lowest position, the first pinion  33  is meshed with the upper end of the second rack  31  since the cylindrical guide  29  is moved to its downward position by means of the first pinion  33 . Also the second pinion  34  is meshed with both the lower end of the third rack  32  and the upper end of the first rack  30 . The intermediate rotary shaft  24  is in its extended position relative to the proximal rotary shaft  22 , and the distal rotary shaft  26  is in its extended position relative to the intermediate rotary shaft  24 . Thus, the arbor is fully extended in its entirety. 
         [0032]    The proximal rotary shaft  22  has a through oil passage  22   a.  The oil passage  22   a  extends along the central axis of the proximal rotary shaft  22 . A valve rod  36  is axially moved within the oil passage  22   a.  With the arbor in its retracted position, a central pilot pin P is held in the position shown in  FIGS. 1 and 3 . In this state, a valve element  36   a,  which is connected to the lower end of the valve rod  36 , is seated against an annular valve seat  26   c  which is formed on the inner peripheral surface of the distal rotary shaft  26 . This causes closing of an oil line  18   a  comprised of the oil passage  22   a  of the proximal rotary shaft  22 , an axial through bore  24   a  (see  FIG. 4 ) of the intermediate rotary shaft  24 , and an axial through bore  26   d  (see  FIG. 4 ) of the distal rotary shaft  26 . More specifically, a seal ring  26   e  is mounted on the valve seat  26   c  (see  FIGS. 3 and 4 ). The valve element  36   a  is sealingly engaged with this seal ring  26   e  to fully close the oil line  18   a.  The oil line  18   a  vertically extends within the arbor  18 . When the arbor  18  is moved from its retracted position to its extended position to cut a hole in the workpiece W, the pilot pin P is held in engagement with the workpiece W. In other words, the pilot pin P is upwardly displaced relative to the arbor (particularly the distal rotary shaft  26 ) when the arbor is extended in a downward direction. As a result of this displacement, the valve element  36   a  is lifted from the valve seat  26   c  so as to open the oil line  18   a  of the arbor  18 . With the oil line  18   a  fully open a cutting oil O is fed from an oil tank  50  to the annular cutter C. 
         [0033]    As shown in  FIGS. 1 and 3 , the oil tank  50  includes a tank body  54  and a flexible vent pipe  56  mounted within the tank body  54 . The tank body  54  has an oil outlet  52  communicated with the inlet port  18   b  of the arbor  18 . The vent pipe  56  has an end  56   a  communicated with ambient atmosphere outside of the oil tank and an other end  56   b.  A float  58  is mounted to the other end  56   b  of the vent pipe  56 . The float  58  causes the other end  56   b  of the vent pipe  56  to be exposed to an air E which is present above the level of the cutting oil O within the tank body  54 . 
         [0034]    In the illustrated embodiment, the machine body  14  has a generally cylindrical portion  14   a  to house the arbor  18 . A cylindrical oil tank mount  14   a  (see  FIGS. 3 and 7 ) extends upwardly from the upper end of the cylindrical portion  14   a  and is disposed in a coaxial relation to the arbor  18 . The oil tank mount  14   a  has a through cavity  14   c  communicated with the inlet port  18   b  of the arbor  18 . 
         [0035]    The tank body  54  is formed on its lower end with a joint  54   a  connected to the oil tank mount  14   b.  The joint  54   a  has a passage  54   b  through which the oil outlet  52  of the tank body  54  and the through cavity  14   c  of the oil tank mount  14   b  are communicated with one another. A rotary valve  60  is disposed within the passage  54   b  so as to adjust the cross sectional area of the passage  54   b  and thus regulate the flow of the cutting oil to be supplied to the annular cutter. The rotary valve  60  is adjustably operated by means of a lever  60   a.  As shown in  FIGS. 1 and 3 , the oil tank mount  14   b  has a small diameter portion  14   d  and a large diameter portion  14   e  located below the small diameter portion  14   d.  The joint  54   a  of the oil tank is fitted over these two portions. As shown in  FIG. 5 , the joint  54   a  has a clamping ring or slit ring  55  disposed about the large diameter portion of the oil tank mount  14   b  and a fastener or screw  54   c  adapted to secure the clamping ring  55  around the large diameter portion of the oil tank mount  14   b.    
         [0036]    In the illustrated embodiment, the tank body  54  has a passage  54   d  defined above the proximal rotary shaft  22  and adapted to provide a communication between the passage  54   b  and the interior of the tank body  54  through a check valve  66 . When the arbor is moved toward its retracted position, an upward flow of air is permitted to enter the interior of the tank body  54  through the check valve  66 . 
         [0037]    The tank body  54  includes a bottom wall  54   e  located adjacent to the machine body  14 , a peripheral wall  54   f  extending from the peripheral edge of the bottom wall  54   e  in a direction away from the machine body  14 , and a top wall  54   g  connected to the peripheral wall and separated a predetermined distance from the bottom wall  54   e.  The oil outlet  52  (located in the left section of the oil tank as shown in  FIGS. 1 and 3 ) is formed in the bottom wall  54   e  adjacent to the peripheral wall  54   f.  As shown in  FIG. 1 , the tank body horizontally extends from the central axis of the arbor more to the right than to the left. In addition, the right side of the bottom wall  54   e  projects toward the machine body relative to the left side of the bottom wall  54   e.    
         [0038]    The tank body  54  has an interior space. The interior space is divided into a first interior part and a second interior part by an imaginary plane containing the central axis of rotation of the arbor. In  FIGS. 1 and 3 , the imaginary plane extends normal to the sheets. The first interior part is less in volume than the second interior part. The tank body  54  is mounted to the machine body and oriented in the desired angular position about the central axis of rotation of the arbor so that the first interior part is located below the second interior part. 
         [0039]      FIG. 6  shows that the rotary cutting machine is attached to the workpiece W which is oriented in a vertical direction rather than in a horizontal direction as shown in  FIGS. 1 to 3 . In this embodiment, the oil tank  50  is mounted to the machine body  14  so that the first interior part of the tank body is located below the second interior part. This arrangement allows the level of the cutting oil O to be higher than the annular cutter as compared the case where the oil tank is positionally maintained as it was relative to the machine body, in other words, the oil tank is placed upside down from the state shown in  FIG. 6 . Better supply of cutting oil results. 
         [0040]    Referring to  FIG. 7 , the oil tank  50  may need to be removed, for example, in the event that the rotary cutting machine is used in a small or narrow site. In such a case, a hose adapter or fitting  62  may preferably be mounted to the oil tank mount  14   b  of the machine body. The hose fitting  62  is in the form of a cap fitted over the oil tank mount  14   b  and includes an outwardly extending connector or nipple  64 . The nipple  64  is connected through to an external hose to a remote oil source (not shown).