Patent Publication Number: US-2023147655-A1

Title: Machine tool

Description:
TECHNICAL FIELD 
     The present invention relates to a machine tool. 
     BACKGROUND ART 
     JP 2018-034248 A discloses a machine tool that machines a workpiece by causing a spindle head to move relative to a table while rotating a spindle on which a cutting tool is mounted. 
     SUMMARY OF THE INVENTION 
     It is desirable to perform a turning process using the machine tool as disclosed in JP 2018-034248 A. The machine tool that carries out the turning process rotates the workpiece while the spindle on which a lathe machining tool is installed is non-rotatably fixed by stopping the operation of a motor. However, the spindle is originally configured in a manner so as to rotate. Therefore, in the machine tool that carries out the turning process, even if the spindle is fixed by the motor, the lathe machining tool that is in contact with the workpiece at the time of the turning process can easily move in the direction of rotation of the spindle. If the lathe machining tool moves during machining, the machining accuracy decreases. 
     An object of the present invention is to provide a machine tool, which is capable of preventing a decrease in the accuracy of a turning process, and is also capable of setting an angle of rotation of the lathe machining tool. 
     A machine tool according to one aspect of the present invention includes a spindle head equipped with a spindle, a tool holder that is configured to retain a lathe machining tool and is installed on the spindle, a fixing member provided on the spindle head and configured to fix the lathe machining tool while enabling an angle of rotation of the lathe machining tool to be adjusted, and a mounting member provided on the tool holder and configured to mount the lathe machining tool on the fixing member at the angle of rotation that has been adjusted, wherein the angle of rotation of the lathe machining tool is adjusted in accordance with a location on the fixing member where the mounting member is mounted. 
     According to the present invention, it is possible to provide the machine tool, which is capable of preventing a decrease in the accuracy of the turning process, and is also capable of setting an angle of rotation of the lathe machining tool. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a side view showing a machine tool according to a first embodiment of the present invention; 
         FIG.  2    is a perspective view showing a portion of the machine tool according to the first embodiment; 
         FIG.  3    is a side view showing a portion of the machine tool according to the first embodiment; 
         FIG.  4    is a side view showing a portion of the machine tool according to the first embodiment; 
         FIG.  5    is a perspective view showing a portion of a machine tool according to a second embodiment; 
         FIG.  6    is a side view showing a portion of the machine tool according to the second embodiment; 
         FIG.  7    is a side view showing a portion of the machine tool according to the second embodiment; 
         FIG.  8    is a perspective view showing a portion of a machine tool according to a third embodiment; 
         FIG.  9    is a side view showing a portion of the machine tool according to the third embodiment; 
         FIG.  10    is a side view showing a portion of the machine tool according to the third embodiment; 
         FIG.  11    is a side view showing a portion of a machine tool according to a fourth embodiment; and 
         FIG.  12    is a side view showing a portion of the machine tool according to the fourth embodiment. 
     
    
    
     DESCRIPTION OF THE INVENTION 
     Preferred embodiments of a machine tool according to the present invention will be presented and described in detail below with reference to the accompanying drawings. 
     First Embodiment 
     A machine tool according to a first embodiment will be described with reference to the drawings.  FIG.  1    is a side view showing the machine tool according to the present embodiment. 
     A machine tool  10  carries out machining on an object to be machined  22 , in other words, a workpiece, by means of a lathe machining tool  18  that is mounted on a spindle  16 . 
     A spindle head  14  is provided on the machine tool  10 . The spindle  16  is provided on the spindle head  14 . A tool holder  20  for retaining the lathe machining tool  18  is detachably installed on the spindle  16 . The spindle  16  is capable of imparting rotational motion to the tool, however, according to the present embodiment, the operation of the motor is stopped, and the lathe machining tool  18  is fixed by a fixing member  50  described later. Moreover, although an example in which only one spindle head  14  is provided is shown in  FIG.  1   , a plurality of the spindle heads  14  may be provided. In addition, the spindle  16  may be provided for each of the plurality of spindle heads  14 . In this case, a plurality of the spindles  16  having similar specifications may be provided, or a plurality of the spindles  16  having different specifications may be provided. Further, the spindle  16  is not limited to any particular type of spindle, and for example, may be an air spindle or the like. 
     The machine tool  10  is equipped with a column  24  that causes the spindle head  14  to move in an upper/lower direction, an additional axis device  26  that rotatably supports the object to be machined  22 , and a table  34  that causes the additional axis device  26  to move in a first direction and a second direction. The first direction and the second direction are perpendicular to each other. The first direction is a Y direction and the second direction is an X direction. Further, a direction perpendicular to the Y direction and the X direction is defined as a Z direction. A downward direction in which gravity acts is a −Z direction, and an upward direction is a +Z direction. An axial direction of the spindle  16  is in parallel with the Z direction. 
     The additional axis device  26  is positioned below the spindle  16 . The additional axis device  26  is equipped with a rotary table  30 . The object to be machined  22  is fixed on the rotary table  30 . The object to be machined  22  can be fixed to the rotary table  30 , for example, by suction, but the present invention is not limited to this feature. The additional axis device  26  is equipped with a tilting mechanism  27  that tilts a rotary axis of the rotary table  30 . The rotary table  30  can be tilted at an arbitrary angle by the tilting mechanism  27 . The rotary axes that are added by the additional axis device  26  are a rotary axis that causes the rotary table  30  to rotate, and a rotary axis that causes the rotary table  30  to be tilted. More specifically, two rotary axes are added by the additional axis device  26 . 
     The machine tool  10  is capable of carrying out three dimensional machining on the object to be machined  22 , by moving the spindle  16  in the Z direction, moving the additional axis device  26  in the X direction and the Y direction, rotating the object to be machined  22  by the additional axis device  26 , and tilting the rotary table  30 . 
     The additional axis device  26  is supported by the table  34 . The table  34  is supported by a saddle  36 . The table  34  is equipped with a non-illustrated X-axis movement mechanism that causes the table  34  to move in the X direction with respect to the saddle  36 . Therefore, the table  34  is capable of moving in the X-axis direction with respect to the saddle  36 . The saddle  36  is supported by a bed  32 . The saddle  36  is equipped with a non-illustrated Y-axis movement mechanism that causes the saddle  36  to move in the Y-axis direction with respect to the bed  32 . Therefore, the saddle  36  is capable of moving in the Y-axis direction with respect to the bed  32 . In this manner, the table  34  is capable of moving in the X and Y directions with respect to the bed  32 . Mechanisms that are widely known can be used for the Y-axis movement mechanism and the X-axis movement mechanism. 
     A non-illustrated splash guard is provided on the machine tool  10 . The splash guard surrounds a machining area of the machine tool  10 . The splash guard serves to prevent cutting fragments including cutting chips, or a cutting fluid or the like, which are generated due to machining, from being scattered into the surrounding area. A non-illustrated nozzle through which the cutting fluid is discharged toward the lathe machining tool  18  during machining is provided in the machining area. The machine tool  10  according to the present embodiment is configured in the foregoing manner. 
       FIG.  2    is a perspective view showing a portion of the machine tool according to the present embodiment.  FIG.  3    and  FIG.  4    are side views showing a portion of the machine tool according to the present embodiment. The configuration in the vicinity of the spindle head  14  is shown in  FIGS.  2  through  4   . A state prior to the tool holder  20  being installed on the spindle  16  is shown in  FIG.  3   . A state after the tool holder  20  has been installed on the spindle  16  is shown in  FIG.  2    and  FIG.  4   . 
     The tool holder (a retaining member)  20  retains the lathe machining tool  18  and is installed on the spindle  16 . As shown in  FIG.  3   , the tool holder  20  includes a columnar shaped member  40 , a protruding portion  42 , and a mounting member  44 . The protruding portion  42  is provided on one main surface of the columnar shaped member  40 . The lathe machining tool  18  is provided on another main surface of the columnar shaped member  40 . The protruding portion  42  protrudes in an axial direction of the lathe machining tool  18 . A turning tip  18   a , and more specifically, a cutting edge is provided, for example, on a distal end part of the lathe machining tool  18 . 
     The fixing member  50  is provided on the spindle head  14 . The fixing member  50  serves to fix the lathe machining tool  18 , while enabling an angle of rotation (an indexing angle) of the lathe machining tool  18  to be adjusted. The fixing member  50  may be formed, for example, from a plate-shaped body whose normal direction is an axial direction of the spindle  16 , but the present invention is not limited to this feature. As shown in  FIG.  2   , a plurality of holes  52 , and more specifically, a plurality of through holes, are formed in the fixing member  50 . Although only three holes  52  are shown in  FIG.  2   , the number of the holes  52  is not necessarily limited to three. 
     The mounting member  44  serves to mount the lathe machining tool  18  on the fixing member  50  at an adjusted angle of rotation. Since the lathe machining tool  18  is not only fixed to the spindle  16  via the tool holder  20 , but the lathe machining tool  18  is also fixed to the fixing member  50  via the mounting member  44  provided on the tool holder  20 , the turning tip  18   a  provided at a distal end of the lathe machining tool  18  is more satisfactorily fixed. As shown in  FIG.  3   , the mounting member  44  is equipped with a first portion  46 A, a second portion  46 B, and a third portion  46 C. The first portion  46 A protrudes from the tool holder  20  in a direction intersecting the axial direction of the lathe machining tool  18 . More specifically, the first portion  46 A protrudes from the tool holder  20  in a direction that is perpendicular to the axial direction of the lathe machining tool  18 . As shown in  FIG.  2   , a planar shape of the first portion  46 A, for example, is a rectangular shape, but the present invention is not limited to this feature. The columnar shaped member  40  and the first portion  46 A may be formed integrally, or may be connected together by welding or the like. Further, the first portion  46 A may be capable of being removed from the columnar shaped member  40 . The first portion  46 A may be fixed to the columnar shaped member  40  by forming an internal thread on the columnar shaped member  40 , for example, by forming an external thread on a distal end of the first portion  46 A, for example, and by screw-engaging the external thread into the internal thread. When the angle of rotation of the lathe machining tool  18  is adjusted, the first portion  46 A rotates integrally with the columnar shaped member  40  about a central axis of the lathe machining tool  18 . 
     The second portion  46 B protrudes from the first portion  46 A. A longitudinal direction of the second portion  46 B, and specifically, the direction in which the second portion  46 B protrudes, is a direction that intersects the longitudinal direction of the first portion  46 A. More specifically, the direction in which the second portion  46 B protrudes is parallel with the axial direction of the lathe machining tool  18 . In other words, the direction in which the second portion  46 B protrudes is the same as the direction in which the protruding portion  42  protrudes. The second portion  46 B is formed, for example, in a columnar shape, and more specifically in a circular columnar shape, but the present invention is not limited to this feature. A lower end of the second portion  46 B is fixed to the first portion  46 A. The distance between the central axis of the lathe machining tool  18  and the central axis of the second portion  46 B is equivalent to the distance between the central axis of the spindle  16  and the central axis of the holes  52 . The first portion  46 A and the second portion  46 B may be formed integrally, or may be connected together by welding or the like. The second portion  46 B may be capable of being removed from the first portion  46 A. The second portion  46 B may be fixed to the first portion  46 A by forming an external thread on the first portion  46 A, for example, by forming an internal thread on the second portion  46 B, for example, and by screw-engaging the external thread into the internal thread. When the angle of rotation of the lathe machining tool  18  is adjusted, the second portion  46 B rotates integrally with the first portion  46 A about the central axis of the lathe machining tool  18 . 
     The third portion  46 C protrudes from the second portion  46 B. The direction in which the third portion  46 C protrudes, for example, is the same as the direction in which the protruding portion  42  protrudes. The third portion  46 C is formed, for example, in the shape of a truncated cone, but the present invention is not limited to this feature. The area of an upper surface of the third portion  46 C is set to be smaller than the area of a lower surface of the third portion  46 C. The diameter of the lower surface of the third portion  46 C is set to be equivalent to the diameter of the holes  52  provided in the fixing member  50 , or to be slightly smaller than the diameter of the holes  52 . A side surface of the third portion  46 C is formed in a tapered shape. Since the side surface of the third portion  46 C is formed in a tapered shape, insertion of the third portion  46 C into the holes  52  is facilitated. The second portion  46 B and the third portion  46 C may be formed integrally, or may be connected together by welding or the like. The third portion  46 C may be capable of being removed from the second portion  46 B. The third portion  46 C may be fixed to the second portion  46 B by forming an external thread on a lower surface side of the third portion  46 C, for example, by forming an internal thread on an upper end of the second portion  46 B, for example, and by screw-engaging the external thread into the internal thread. 
     When the tool holder  20  is installed on the spindle  16 , the protruding portion  42  is inserted into an installation hole  16   a  that is formed in a lower end part of the spindle  16 . 
     When the protruding portion  42  is inserted into the installation hole  16   a , the third portion  46 C is inserted into any one of the plurality of holes  52 . By the third portion  46 C being inserted into the holes  52 , the mounting member  44  is locked by the fixing member  50 . Consequently, a state is brought about in which the mounting member  44  does not rotate about the central axis of the lathe machining tool  18 . In other words, the mounting member  44  is fixed to the fixing member  50  in the holes  52 . The angle of rotation of the lathe machining tool  18  differs depending on which one of the holes  52  the third portion  46 C is inserted into. More specifically, the angle of rotation of the lathe machining tool  18  is adjusted in accordance with the location on the fixing member  50  where the mounting member  44  is mounted. 
     In the case it is desired to change the angle of rotation of the lathe machining tool  18 , the tool holder  20  is removed from the spindle  16 . When the tool holder  20  is t removed from the spindle  16 , a state is brought about in which the third portion  46 C is not inserted into the holes  52 . When the tool holder  20  is installed again in a manner so that the third portion  46 C is inserted into the hole  52  that differs from the hole  52  into which the third portion  46 C was formerly inserted, the angle of rotation of the lathe machining tool  18  is changed. In this manner, when the tool holder  20  is installed, by appropriately selecting the hole  52  into which the third portion  46 C is inserted, the angle of rotation of the lathe machining tool  18  is adjusted. 
     In the foregoing manner, according to the present embodiment, the fixing member  50  for fixing the lathe machining tool  18  while enabling the angle of rotation of the lathe machining tool  18  to be adjusted is provided on the spindle head  14 , and the mounting member  44  for mounting the lathe machining tool  18  on the fixing member  50  at the adjusted angle of rotation is provided on the tool holder  20 . According to the present embodiment, since the lathe machining tool  18  is not only fixed to the spindle  16  via the tool holder  20 , but the lathe machining tool  18  is also fixed to the fixing member  50  via the mounting member  44  provided on the tool holder  20 , the turning tip  18   a  provided at the distal end of the lathe machining tool  18  is more satisfactorily fixed. In addition, according to the present embodiment, the angle of rotation of the lathe machining tool  18  is adjusted in accordance with the location on the fixing member  50  where the mounting member  44  is mounted. Therefore, according to the present embodiment, it is possible to provide the machine tool  10 , which is capable of preventing a decrease in the accuracy of the turning process, and is also capable of setting the angle of rotation of the lathe machining tool  18 . 
     Second Embodiment 
     A machine tool according to a second embodiment will be described with reference to  FIGS.  5  through  7   .  FIG.  5    is a perspective view showing a portion of the machine tool according to the present embodiment.  FIG.  6    and  FIG.  7    are side views showing a portion of the machine tool according to the present embodiment. A state prior to the tool holder  20  being installed on the spindle  16  is shown in  FIG.  6   . A state after the tool holder  20  has been installed on the spindle  16  is shown in  FIG.  5    and  FIG.  7   . The same constituent elements as those of the machine tool according to the first embodiment shown in  FIGS.  1  through  4    are designated by the same reference numerals, and description thereof will be omitted or referred to in an abbreviated manner. 
     In the machine tool  10  according to the present embodiment, a plurality of connecting members  54  are provided in the fixing member  50 , and a mounting member  44 A is fixed to the fixing member  50  via any one of the plurality of connecting members  54 . 
     As shown in  FIG.  6   , in the present embodiment, the mounting member  44 A is constituted by the first portion  46 A, and the third portion  46 C. The third portion  46 C protrudes from the first portion  46 A. 
     As shown in  FIG.  5   , the fixing member  50  is equipped with the plurality of connecting members  54 . The plurality of connecting members  54  protrude from the fixing member  50  in a direction toward the mounting member  44 A. The plurality of connecting members  54  are fixed, for example, in the plurality of holes  52 , respectively. The connecting members  54  are fixed to the fixing member  50 , for example, using bolts  56 , but the present invention is not limited to this feature. The connecting members  54  may be fixed to the fixing member  50  by forming an external thread on the connecting members  54 , for example, by forming an internal thread on the fixing member  50 , for example, and by screw-engaging the external thread into the internal thread. Further, the fixing member  50  and the connecting members  54  may be formed integrally, or may be connected together by welding or the like. Holes  58  are formed in lower end parts of the connecting members  54 . The third portion  46 C is inserted into the holes  58 . The diameter of the holes  58  is set to be equivalent to the diameter of the lower surface of the third portion  46 C, or to be slightly larger than the diameter of the lower surface of the third portion  46 C. 
     When the tool holder  20  is installed on the spindle  16 , the protruding portion  42  is inserted into the installation hole  16   a  that is formed in the lower end part of the spindle  16  and the third portion  46 C is inserted into the hole  58  of any one of the plurality of connecting members  54 . By the third portion  46 C being inserted into the holes  58 , the mounting member  44 A is locked by the fixing member  50  via the connecting members  54 . Consequently, a state is brought about in which the mounting member  44 A does not rotate about the central axis of the lathe machining tool  18 . The angle of rotation of the lathe machining tool  18  differs depending on which one of the connecting members  54  the third portion  46 C is engaged with. More specifically, the angle of rotation of the lathe machining tool  18  is adjusted in accordance with the location on the fixing member  50  where the mounting member  44 A is mounted. 
     In the case it is desired to change the angle of rotation of the lathe machining tool  18 , the tool holder  20  is removed from the spindle  16 . When the tool holder  20  is removed from the spindle  16 , a state is brought about in which the third portion  46 C is not inserted into the holes  58 . When the tool holder  20  is installed again in a manner so that the mounting member  44 A is engaged with the connecting member  54  that differs from the connecting member  54  with which the mounting member  44 A was formerly engaged, the angle of rotation of the lathe machining tool  18  changes. In this manner, when the tool holder  20  is installed, by appropriately selecting the connecting member  54  with which the mounting member  44 A is engaged, the angle of rotation of the lathe machining tool  18  is adjusted. 
     In this manner, according to the present embodiment, the plurality of connecting members  54  are provided in the fixing member  50 , and the mounting member  44 A is fixed to the fixing member  50  via any one of the plurality of connecting members  54 . In the present embodiment as well, since the lathe machining tool  18  is not only fixed to the spindle  16  via the tool holder  20 , but the lathe machining tool  18  is also mounted on the fixing member  50  via the mounting member  44 A provided on the tool holder  20 , the turning tip  18   a  provided at the distal end of the lathe machining tool  18  is satisfactorily fixed. In addition, the angle of rotation of the lathe machining tool  18  is adjusted in accordance with the location of the connecting member  54  with which the mounting member  44 A is engaged. Therefore, in the present embodiment as well, it is possible to provide the machine tool  10 , which is capable of preventing a decrease in the accuracy of the turning process, and is also capable of setting the angle of rotation of the lathe machining tool  18 . 
     Third Embodiment 
     A machine tool according to a third embodiment will be described with reference to  FIGS.  8  through  10   .  FIG.  8    is a perspective view showing a portion of the machine tool according to the present embodiment.  FIG.  9    and  FIG.  10    are side views showing a portion of the machine tool according to the present embodiment. A state prior to the tool holder  20  being installed on the spindle  16  is shown in  FIG.  9   . A state after the tool holder  20  has been installed on the spindle  16  is shown in  FIG.  8    and  FIG.  10   . The same constituent elements as those of the machine tools according to the first and second embodiments shown in  FIGS.  1  through  7    are designated by the same reference numerals, and description thereof will be omitted or referred to in an abbreviated manner. 
     In the machine tool  10  according to the present embodiment, the fixing member  50  is equipped with an arcuate slit  60 , and a mounting member  44 B is fixed to the fixing member  50  in the slit  60 . 
     As shown in  FIG.  9   , in the present embodiment, the mounting member  44 B is constituted by the first portion  46 A, the second portion  46 B, and the third portion  46 C. According to the present embodiment, the first portion  46 A is formed to be longer, and a clamping device  62  is fixed on the first portion  46 A. 
     The clamping device  62  serves to fix the mounting member  44 B to the fixing member  50  at an arbitrary location within the slit  60 . As the clamping device  62 , for example, a hydraulic clamping device or the like can be used, but the present invention is not limited to this feature. A rod  64  is provided on the clamping device  62 . The clamping device  62  is capable of displacing the rod  64  in an upper/lower direction. 
     The installation of the tool holder  20  on the spindle  16  is performed, for example, in the following manner. More specifically, in a state in which the rod  64  of the clamping device  62  is raised, the protruding portion  42  is inserted into the installation hole  16   a  formed in the lower end part of the spindle  16 , and the third portion  46 C is inserted into the arcuate slit  60  that is formed in the fixing member  50 . Thereafter, by lowering the rod  64  of the clamping device  62 , the fixing member  50  is sandwiched between the second portion  46 B of the mounting member  44 B and the rod  64  of the clamping device  62 . Consequently, the mounting member  44 B is fixed to the fixing member  50 , and a state is brought about in which the mounting member  44 B does not rotate about the central axis of the lathe machining tool  18 . The angle of rotation of the lathe machining tool  18  differs depending on the location within the arcuate slit  60  at which the mounting member  44 B is fixed to the fixing member  50 . More specifically, the angle of rotation of the lathe machining tool  18  is adjusted in accordance with the location on the fixing member  50  where the mounting member  44 B is mounted. 
     In the case it is desired to change the angle of rotation of the lathe machining tool  18 , the rod  64  of the clamping device  62  is raised. When the rod  64  of the clamping device  62  is raised, a state is brought about in which the mounting member  44 B is not fixed to the fixing member  50 . Consequently, the angle of rotation of the lathe machining tool  18  can be changed. After the angle of rotation of the lathe machining tool  18  has been changed, the rod  64  of the clamping device  62  is lowered. By lowering the rod  64  of the clamping device  62 , the fixing member  50  is sandwiched between the second portion  46 B of the mounting member  44 B and the rod  64  of the clamping device  62 . Consequently, the mounting member  44 B is fixed to the fixing member  50 , and a state is brought about in which the mounting member  44 B does not rotate about the central axis of the lathe machining tool  18 . In this manner, the angle of rotation of the lathe machining tool  18  is changed. 
     In the foregoing manner, according to the present embodiment, the fixing member  50  is equipped with the arcuate slit  60 , and the mounting member  44 B is fixed to the fixing member  50  in the slit  60 . In the present embodiment as well, since the lathe machining tool  18  is not only fixed to the spindle  16  via the tool holder  20 , but the lathe machining tool  18  is also mounted on the fixing member  50  via the mounting member  44 B provided on the tool holder  20 , the turning tip  18   a  provided at the distal end of the lathe machining tool  18  is satisfactorily fixed. In accordance with the present embodiment, since the mounting member  44 B can be fixed to the fixing member  50  at an arbitrary location within the slit  60 , it becomes possible to perform a fine adjustment of the angle of rotation of the lathe machining tool  18 . 
     Fourth Embodiment 
     A machine tool according to a fourth embodiment will be described with reference to  FIG.  11    and  FIG.  12   .  FIG.  11    and  FIG.  12    are side views showing a portion of the machine tool according to the present embodiment. A state prior to the tool holder  20  being installed on the spindle  16  is shown in  FIG.  11   . A state after the tool holder  20  has been installed on the spindle  16  is shown in  FIG.  12   . The same constituent elements as those of the machine tools according to the first through third embodiments shown in  FIGS.  1  through  10    are designated by the same reference numerals, and description thereof will be omitted or referred to in an abbreviated manner. 
     In the machine tool  10  according to the present embodiment, the arcuate slit  60  (see  FIG.  8   ) is not provided in the fixing member  50 . In the present embodiment as well, in the same manner as in the third embodiment, a mounting member  44 C is fixed to the fixing member  50  by the clamping device  62 . 
     As shown in  FIG.  11   , in the present embodiment, the mounting member  44 C is constituted by the first portion  46 A and the second portion  46 B. In the present embodiment as well, in the same manner as in the third embodiment, the first portion  46 A is formed to be longer, and the clamping device  62  is provided on the first portion  46 A. 
     The installation of the tool holder  20  on the spindle  16  is performed, for example, in the following manner. More specifically, in a state in which the rod  64  of the clamping device  62  is raised, the protruding portion  42  is inserted into the installation hole  16   a  that is formed in the lower end part of the spindle  16 . Thereafter, by lowering the rod  64  of the clamping device  62 , the fixing member  50  is sandwiched between the second portion  46 B of the mounting member  44 C and the rod  64  of the clamping device  62 . Consequently, the mounting member  44 C is fixed to the fixing member  50 , and a state is brought about in which the mounting member  44 C does not rotate about the central axis of the lathe machining tool  18 . The angle of rotation of the lathe machining tool  18  differs depending on the location at which the mounting member  44 C is fixed to the fixing member  50 . More specifically, the angle of rotation of the lathe machining tool  18  is adjusted in accordance with the location on the fixing member  50  where the mounting member  44 C is mounted. 
     In the case it is desired to change the angle of rotation of the lathe machining tool  18 , the rod  64  of the clamping device  62  is raised. When the rod  64  of the clamping device  62  is raised, a state is brought about in which the mounting member  44 C is not fixed to the fixing member  50 . Consequently, the angle of rotation of the lathe machining tool  18  can be changed. After the angle of rotation of the lathe machining tool  18  has been changed, the rod  64  of the clamping device  62  is lowered. By lowering the rod  64  of the clamping device  62 , the fixing member  50  is sandwiched between the second portion  46 B of the mounting member  44 C and the rod  64  of the clamping device  62 . Consequently, the mounting member  44 C is fixed to the fixing member  50 , and a state is brought about in which the mounting member  44 C does not rotate about the central axis of the lathe machining tool  18 . In this manner, the angle of rotation of the lathe machining tool  18  is changed. 
     In the foregoing manner, the arcuate slit  60  need not necessarily be provided in the fixing member  50 . In the present embodiment as well, since the lathe machining tool  18  is not only fixed to the spindle  16  via the tool holder  20 , but the lathe machining tool  18  is also mounted on the fixing member  50  via the mounting member  44 C provided on the tool holder  20 , the turning tip  18   a  provided at the distal end of the lathe machining tool  18  is satisfactorily fixed. Further, in the present embodiment as well, the mounting member  44 C is fixed to the fixing member  50  by the clamping device  62 . Also in the present embodiment, since the mounting member  44 C can be fixed at an arbitrary location, it becomes possible to perform a fine adjustment of the angle of rotation of the lathe machining tool  18 . 
     Modified Embodiments 
     Although preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications are capable of being made thereto without departing from the essence and gist of the present invention. 
     For example, in the third embodiment, although an exemplary case has been described in which the mounting member  44 B is fixed to the fixing member  50  by the clamping device  62 , the present invention is not limited to this feature. The mounting member  44 B may be fixed to the fixing member  50  using a fastening member other than the clamping device  62 . The mounting member  44 B may be fixed to the fixing member  50 , for example, by forming an internal thread on an upper surface side of the third portion  46 C, and by screw-engaging an external thread provided on a non-illustrated wing bolt or the like into the internal thread. 
     The above-described embodiments may be summarized in the following manner. 
     The machine tool ( 10 ) includes the spindle head ( 14 ) equipped with the spindle ( 16 ), the tool holder ( 20 ) that retains the lathe machining tool ( 18 ) and is installed on the spindle, the fixing member ( 50 ) provided on the spindle head and configured to fix the lathe machining tool while enabling the angle of rotation of the lathe machining tool to be adjusted, and the mounting member ( 44 ) provided on the tool holder and configured to mount the lathe machining tool on the fixing member at the adjusted angle of rotation, wherein the angle of rotation of the lathe machining tool is adjusted in accordance with the location on the fixing member where the mounting member is mounted. In accordance with such a configuration, since the lathe machining tool is not only fixed to the spindle via the tool holder, but the lathe machining tool is also mounted on the fixing member via the mounting member provided on the tool holder, the turning tip provided at the distal end of the lathe machining tool is satisfactorily fixed. In addition, in accordance with such a configuration, the angle of rotation of the lathe machining tool is adjusted in accordance with the location on the fixing member where the mounting member is mounted. Therefore, in accordance with such a configuration, it is possible to provide the machine tool, which is capable of preventing a decrease in the accuracy of the turning process, and is also capable of setting the angle of rotation of the lathe machining tool. 
     The fixing member may be a plate-shaped body whose normal direction is an axial direction of the spindle. 
     The plurality of holes ( 52 ) may be provided in the fixing member, and the mounting member may be fixed to the fixing member in any one of the plurality of holes. 
     The mounting member may include the first portion ( 46 A) that protrudes from the tool holder in a direction intersecting the axial direction of the lathe machining tool, and the second portion ( 46 B) that protrudes from the first portion toward the fixing member, and the second portion may be fixed to the fixing member. 
     The plurality of connecting members ( 54 ) may be provided in the fixing member, and the mounting member may be fixed to the fixing member via any one of the plurality of connecting members. 
     The arcuate slit ( 60 ) may be formed in the fixing member, and the mounting member may be fixed to the fixing member in the slit. In accordance with such a configuration, since the mounting member can be fixed at an arbitrary location within the slit, it becomes possible to perform a fine adjustment of the angle of rotation of the lathe machining tool. 
     The clamping device ( 62 ) may further be provided, and the mounting member may be fixed to the fixing member by the clamping device.