Patent Publication Number: US-2021162511-A1

Title: Tool attachment part, tool post of machine tool equipped with tool attachment part, and machine tool

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 15/300,161, filed Sep. 28, 2016, which is the U.S. National Phase under 35 U.S.C. § 371 of International Application No. PCT/JP2015/060036, filed Mar. 31, 2015, designating the U.S., and published in Japanese as WO 2015/152192 A1 on Oct. 8, 2015, which claims priority to Japanese Patent Application No. 2014-073260, filed Mar. 31, 2014, the entire contents of which are incorporated herein by reference. 
    
    
     BACKGROUND 
     This disclosure relates to a tool attachment part for attaching a tool, a tool post of a machine tool equipped with the tool attachment part, and the machine tool. 
     DESCRIPTION OF THE RELATED ART 
     A turret tool post that is provided at an automatic lathe and includes a turret turnably supported by a post body has been known. With the turret tool post, a tool such as a bite and an end mill is turnably attached to the turret with a tool attachment part. 
     The above turret tool post rotates a rotatable tool attached to the tool attachment part and turns the rotatable tool relative to the turret so as to process a workpiece (see Patent Literature 1 and Patent Literature 2).
     Patent Literature 1: JP3129696 U   Patent Literature 2: JP2013-226611 A   

     Patent Literature 1 discloses a tool post including tool-attachment-part turning means for turning the tool (tool attachment part). The tool-attachment turning means is, however, configured with a plurality of gears complicatedly connected to each other. Patent Literature 2 discloses a tool post including a turret turning drive shaft that has a cylindrical shape and transmits a turn force to the turret, a rotatable-tool drive shaft attached to the tool attachment part (tool unit), and a turning drive shaft that transmits a turn force to the tool unit to turn the rotation shaft of the tool. However, the rotatable-tool drive shaft and the turning drive shaft are attached inside the turret turning drive shaft. Namely, the structure of the turret tool post is complicated. 
     SUMMARY 
     An object of the present disclosure is, therefore, to provide a tool attachment part that can turn a tool supported by the tool attachment part with a simple structure, a tool post of a machine tool equipped with the tool attachment part, and the machine tool. 
     In order to achieve the above object, a tool attachment part according to an embodiment of the present disclosure is a tool attachment part turnably holding a tool and attached to a tool post of a machine tool. The tool attachment part includes an outer holder that is detachably fixed to a fixed part formed on the tool post, and an inner holder that is turnably and integrally supported by the outer holder. The inner holder is formed with a support part to support the tool. Drive-force input part is provided to be associated with the inner holder. Here, the drive-force input part is detachably engaged with drive-force transmission part provided on the tool post side. The outer holder is fixed to the fixed part and is detachably attached to the tool post, and the drive-force input part is engaged with the drive-force transmission part such that the inner holder turns and thereby the tool supported by the support part turns. 
     A tool post of a machine tool equipped with a tool attachment part according to another embodiment of the present invention is a tool post of a machine tool including a tool attachment part turnably holding a tool and a body part attached with the tool attachment part, and the tool held by the tool attachment part is turned to process a material. The tool post includes drive-force transmission part that includes a fixed part to detachably fix the tool attachment part to the body part side and that is configured to turn the tool. The tool attachment part includes an outer holder that is detachably fixed to the fixed part and an inner holder that is turnably and integrally supported by the outer holder. The inner holder is formed with a support part to support the tool and is associated with drive-force input part, the drive-force input part detachably engaged with the drive-force transmission part. The drive-force input part is detachably attached to the body part by fixing the outer holder to the fixed part and is engaged with the drive-force transmission means such that the inner holder turns, and thereby the tool supported by the support part turns. 
     A machine tool according to another embodiment of the present invention includes the above-mentioned tool post. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic perspective view illustrating a vicinity of a main spindle of an automatic lathe, which is one example of a machine tool equipped with a tool post and a tool attachment part according to an embodiment. 
         FIG. 2  is a schematic cross-sectional view along an X-axis direction illustrating an internal structure of the tool post according to an embodiment. 
         FIG. 3  is a schematic cross-sectional view illustrating a vicinity of a turret attached to the tool post according to an embodiment. 
         FIG. 4  is a schematic cross-sectional view illustrating a vicinity of a turret attached to a turret tool post according to an embodiment. 
         FIG. 5  is a schematic cross-sectional view illustrating a vicinity of a turret attached to a turret tool post according to an embodiment. 
         FIG. 6  is a schematic cross-sectional view illustrating a vicinity of a turret attached to a turret tool post according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a schematic perspective view illustrating a vicinity of a main spindle of an automatic lathe, which is one example of a machine tool equipped with a turret tool post according to an embodiment.  FIG. 2  is a schematic cross-sectional view illustrating an internal structure of the turret tool post according to an embodiment. 
     A main spindle  2  of an automatic lathe  1  is rotatably mounted on a main spindle headstock  3 . A distal end part of the main spindle  2  detachably grips a workpiece W with a main spindle chuck (not illustrated). A turret tool post  10  is disposed in a vicinity of the main spindle  2 . Note that in this embodiment, a direction along a main-spindle axis line C is defined as a Z-axis direction, a horizontal direction orthogonal to the Z-axis direction is defined as an X-axis direction, and an up-and-down direction orthogonal to both the Z-axis direction and the X-axis direction is defined as a Y-axis direction. 
     The turret tool post  10  includes a post body  11  and a turret  12  having a substantially polygonal shape. The turret  12  is supported by the post body  11  in an indexable and turnable manner. Various tools  14  are detachably attached to a plurality of turret faces  13  on the circumferential surface of the turret  12 , respectively. Using the turret tool post  10  as a support, each of the tools  14  is turnably supported by the turret tool post  10  with the turret  12 . 
     With an indexing turn of the turret  12 , each of tools  14  turns and a desired tool  14  is selectively positioned at a processing position corresponding to a position of the workpiece W. Here, the post body  11  is configured to be controlled by a non-illustrated moving mechanism to move in the X, Y, and Z-axes directions. In accordance with the movement of the turret tool post  10 , the workpiece W is processed by the tool  14  selected by the indexing turn of the turret  12 . 
     As illustrated in  FIG. 2 , a cylindrical fixed shaft  22  is fixed inside the post body  11  along the Z-axis direction. A cylindrical tool-rotation drive shaft  21  is inserted into and rotatably supported by the fixed shaft  22  with bearings  24   a ,  24   b . Further, a turret turning shaft  23  is rotatably fitted onto the fixed shaft  22 . A pipe  20  is inserted into the tool-rotation drive shaft  21 . Here, the pipe  20  is fixed to the post body  11 . 
     A pulley  26  is attached to one distal end side (i.e., the right side on  FIG. 2 ) of the tool-rotation drive shaft  21 , and a pulley  29  is attached to a motor shaft  28   a  of a tool rotating motor  28 . The pulley  26  and the pulley  29  are connected via a belt  27 . With this, a rotation force of the tool rotating motor  28  is transmitted to the tool-rotation drive shaft  21  through the pulley  29 , the belt  27 , and the pulley  26 . A bevel gear  30  is provided at the other distal end side (i.e., the left side on  FIG. 2 ) of the tool-rotation drive shaft  21 . 
     A turret turning gear  34  is integrally attached to one distal end side (i.e., right side on  FIG. 2 ) of the turret turning shaft  23 . A drive force of a turret turning motor (not illustrated) is transmitted to the turret turning gear  34 . The turret  12  is integrally fixed to the other distal end side (i.e., the left side on  FIG. 2 ) of the turret turning shaft  23 . The turret  12  is turnably supported by the post body  11  with the turret turning shaft  23 . 
     A sliding shaft  35  is fitted onto the turret turning shaft  23  with bearings  25   a ,  25   b  so as to be slidable in the Z-axis direction. The bearings  25   a ,  25   b  allow the sliding shaft  35  to slide in the Z-axis direction. At a distal end side of the sliding shaft  35 , a piston  35   a  is formed and inserted into a cylinder chamber  40  that is formed in the post body  11 . Further, a coupling element  41 , which configures a coupling mechanism, is integrally fixed at the distal end side of the sliding shaft  35 . Coupling elements  42  and  43 , which face the coupling element  41 , are integrally fixed to the post body  11  and the turret turning shaft  23  respectively. Here, the coupling element  41 , the coupling element  42 , and the coupling element  43  configure the coupling mechanism. 
     When the sliding shaft  35  is moved to the turret head side (i.e., the left side of  FIG. 2 ) by operating the piston  35   a , the coupling element  41  is engaged with the coupling elements  42 ,  43 . The coupling element  42  fixed to the post body  11  is then engaged with the coupling element  43  fixed to the turret turning shaft  23  through the coupling element  41 . Accordingly, the turn of the turret turning shaft  23  is stopped. When the sliding shaft  35  is slid to disengage the coupling element  41  from the coupling elements  42 ,  43 , the coupling element  42  and the coupling element  43  are separated. As a result, the turret turning shaft  23  is allowed to turn. 
     By allowing the turret turning shaft  23  to turn and turning the turret turning shaft  23 , the turret  12  is turned. The turn of the turret turning shaft  23  is then stopped at a predetermined turning angle position to achieve the indexing turn of the turret  12 . With the indexing turn of the turret  12 , a predetermined turret face  13  of the turret  12  is selected so as to select a desired tool  14 . 
     A support part  44  is fixed at a distal end of the fixed shaft  22 . The support part  44  is positioned inside a hollow part  12   a  of the turret  12 . The support part  44  is integrally fixed to the post body  11  with the fixed shaft  22 . A tool-rotation transmission shaft  32  is rotatably supported by the support part  44 . A bevel gear  31  is attached to a distal end side of the tool-rotation transmission shaft  32 . The bevel gear  31  is engaged with the bevel gear  30 . The drive force is thereby transmitted to the tool-rotation transmission shaft  32  from the tool rotation shaft  21 . 
     A fixed part  13   a  has a cylindrical shape and is formed on the turret face  13 . As illustrated in  FIG. 2  and  FIG. 3 , a rotatable tool device T is detachably fixed to the fixed part  13   a  with a tool attachment part  15 A. Here, the rotatable tool device T holds a rotatable tool  14   a  such as a drill and an end mill as the tool  14 , and the tool attachment part  15  is configured with an outer holder  50  and an inner holder  52 . 
     The tool attachment part  15 A includes the cylindrical outer holder  50  detachably fixed to an inner circumferential surface of the fixed part  13   a , the inner holder  52  integrally and turnably supported at inside of the outer holder  50  with a bearing  51 , and a drive-force transmission gear  53  provided on an outer circumferential surface on a distal end of the inner holder  52 . The inner holder  52  has a hollow cylindrical shape. The hollow part of the inner holder  52  forms a support part to support the rotatable tool  14   a  with the rotatable tool device T. The rotatable tool device T is inserted into the inner holder  52  with a cylindrical insertion portion Tb thereof and thereby detachably fixed to the inner holder  52  with a flange Ta. Here, the flange Ta is provided on a distal end side of the insertion portion Tb. A tool-rotation input shaft  33  provided at a distal end part of the insertion portion Tb is protruded toward the inside of the turret  12  through the hollow part of the inner holder  52 . Similar to a conventional device, the rotatable tool device T is configured such that the rotatable tool  14   a  is rotated by rotating the tool-rotation input shaft  33 . 
     The drive-force transmission gear  53  is arranged to be engaged with a tool turning drive gear  54  when the tool attachment part  15 A is attached inside the fixed part  13   a . The drive-force transmission gear  53  and the tool turning drive gear  54  are both configured with bevel gears to engage with each other. 
     The tool turning drive gear  54  is connected to a drive-force transmission part  62 . The drive-force transmission part  62  is connected to a motor shaft  61  of a tool turning motor  60 . 
     The drive-force transmission part  62  includes a pulley  63  connected to the motor shaft  61  of the tool turning motor  60 , a rotation shaft  66  rotatably supported by a fixed shaft  64  with a bearing  65 , a pulley  67  attached to an outer circumferential surface of the rotation shaft  66 , and a belt  68  stretched between the pulley  63  and the pulley  67 . The tool turning drive gear  54  is integrally attached to the outer circumferential surface of the rotation shaft  66 . 
     As described above, the drive-force transmission gear  53  that is engaged with the tool turning drive gear  54  is provided to be associated with the inner holder  52 . Here, the drive-force transmission gear  53  corresponds to drive-force input part, and the tool turning drive gear  54  corresponds to drive-force transmission part. 
     The tool turning motor  60  is attached to a hollow cover member  69  positioned outside of an end face  12   b  of the turret  12 . The motor shaft  61 , the pulley  63 , the belt  68 , and the rotation shaft  66  on the pulley  67  side are accommodated inside the cover member  69 . The rotation shaft  66  on the tool turning drive gear  54  side is provided inside the hollow part  12   a . The cover member  69  is supported and fixed by the post body  11  with a support fixing part  70 . The cover member  69  on the opposite side to the tool turning motor  60  side is positioned close to the outer circumferential surface of the rotation shaft  66  and surrounds the rotation shaft  66 . Note that the tool turning motor  60  and the cover member  69 , which are positioned outside of the end face  12   b  of the turret  12 , are not illustrated in  FIG. 1 . 
     The fixed shaft  64  is integrally formed with a bracket  71  that is provided on the support part  44  inside the hollow part  12   a . The rotation shaft  66  is disposed in a central opening part  12   c  formed on the end face  12   b  so as to be arranged along the Z-axis direction. The central opening part  12   c  is substantially in contact with the outer circumferential surface of the rotation shaft  66  so as to allow the turret  12  to turn and to prevent, for example, a chip from entering inside the hollow part  12   a.    
     The tool attachment part  15 A is attached to the fixed part  13   a  on the predetermined turret face  13 . When the rotatable tool  14   a  (rotatable tool device T) held by the tool attachment part  15 A is selected, the tool-rotation input shaft  33  is connected to the tool-rotation transmission shaft  32 . Note that a clutch mechanism  72  is configured between the tool-rotation input shaft  33  and the tool-rotation transmission shaft  32 . The clutch mechanism  72  is engaged only when the rotatable tool  14   a  attached to the tool attachment part  15 A is selected. 
     The clutch mechanism  72  includes a groove  32   a  formed at a distal end of the tool-rotation transmission shaft  32  and a tenon-shaped projection  33   a  formed at a distal end of the tool-rotation input shaft  33 . When the rotatable tool  14   a  is selected by turning the turret  12 , the tenon-shaped projection  33   a  is engaged with (fitted to) the groove  32   a . When the tenon-shaped projection  33   a  is engaged with the groove  32   a , the clutch mechanism  72  becomes in an engaged state. 
     When the rotatable tool  14   a  on the tool attachment part  15 A is selected by turning the rotatable tool  14   a  to the indexing position, the clutch mechanism  72  becomes in the engaged state. Accordingly, the rotation force generated by the tool rotating motor  28  is transmitted to the rotatable tool device T through the motor shaft  28   a , the pulley  29 , the belt  27 , the pulley  26 , the tool rotation shaft  21 , the bevel gear  30 , the bevel gear  31 , the tool rotation transmission shaft  32 , the clutch mechanism  72 , and the tool-rotation input shaft  33 . As a result, rotatable tool  14   a  is rotated around the shaft thereof by the rotation force transmitted to the rotatable tool device T and performs cutting process or the like on the workpiece W. 
     By rotating the tool turning motor  60 , a turn force is transmitted to the inner holder  52  through the motor shaft  61 , the belt  68 , the rotation shaft  66 , the tool turning drive gear  54  and the drive-force transmission gear  53 . Since the rotatable tool device T is integrally fixed to the inner holder  52 , the rotatable tool  14   a  is turned on the turret face  13  by the transmitted turn force together with the rotatable tool device T. As a result, it becomes possible to perform processing on the workpiece W under a state in which the rotatable tool  14   a  is inclined by a predetermined angle relative to the outer circumferential surface of or end face of the workpiece W. 
     As described above, in this embodiment, the tool attachment part  15 A is attached to the fixed part  13   a  on the predetermined turret face  13  and the rotatable tool device T is installed on the tool attachment part  15 A. With this, the rotatable tool device T itself is turned, and the rotatable tool  14   a  is thereby turned integrally with the rotatable tool device T. Therefore, it becomes possible to turn the rotatable tool on a general rotatable tool device, in which the rotatable tool is fixedly supported with respect to the turning direction, with a simple structure. Namely, it does not require a dedicated rotatable tool device in which the tool attachment part rotatably attached with the rotatable tool  14   a  is provided to be turnable with respect to the fixed part fixed on the turret face  13 . 
       FIG. 4  is a schematic cross-sectional view illustrating a vicinity of a turret  12  attached to a turret tool post  10   a  according to an embodiment. The turret  12  of this embodiment is substantially identical to that of the earlier discussed embodiment, except for the configurations of a vicinity of a drive-force transmission part  90  and a tool attachment part  15 B. Hence, the detailed description is omitted. 
     Similar to the tool attachment part  15 A, the tool attachment part  15 B of this embodiment is detachably attached to inside a fixed part  13   a . The fixed part  13   a  is formed on a predetermined turret face  13  (illustrated in  FIG. 1 ) of the turret  12 . 
     The tool attachment part  15 B includes a cylindrical outer holder  50  detachably fixed to an inner circumferential surface of the fixed part  13   a , an inner holder  52  turnably and integrally supported at inside of the outer holder  50  with a bearing  51 , and a drive-force transmission gear  53  provided around a center of an outer circumferential surface of the inner holder  52 . 
     The inner holder has a hollow cylindrical shape. The hollow part of the inner holder  52  forms a support part to support a rotatable tool  14   a  with a rotatable tool device T. The rotatable tool device T is inserted into the inner holder  52  with a cylindrical insertion portion Tb thereof and thereby detachably fixed to the inner holder  52  with a flange Ta. Here, the flange Ta is provided on a distal end side of the insertion portion Tb. 
     A turn input shaft  80  is rotatably supported inside the outer holder  50 . The turn input shaft  80  is integrally attached with a tool turning drive gear  54 . The tool turning drive gear  54  is engaged with the drive-force transmission gear  53 . The drive-force transmission gear  53  and the tool turning drive gear  54  are both configured with spur gears to engage with each other. 
     The drive-force transmission part  90  is configured on the turret  12  side. The drive-force transmission part  90  includes a turn shaft  91  connected to a motor shaft  61  of a tool turning motor  60 , a gear  92  attached to the turn shaft  91 , a gear  94  attached to a rotation shaft  93  and engaged with the gear  92 , a gear  95  attached to the rotation shaft  93 , a gear  96  engaged with the gear  95 , and a turn transmission shaft  97  attached with the gear  96 . 
     The turn shaft  91  and the rotation shaft  93  are rotatably supported inside a cover member  69  with bearings  100   a ,  100   b ,  101   a ,  101   b . Here, the bearings  100   a ,  100   b ,  101   a ,  101   b  are provided on the cover member  69  side. The turn transmission shaft  97  is rotatably supported by a support body  45  with a bearing  102  and is arranged to be substantially in parallel to a tool-rotation transmission shaft  32 . Note that the support body  45  is integrally provided on a support part  44 . The drive-force transmission part  90  is provided in the hollow part  12   a  of the turret  12  and inside the hollow cover member  69  and is connected to the motor shaft  61  of the tool turning motor  60 . 
     The hollow cover member  69 , which is attached with the tool turning motor  60 , is connected to a distal end side of a support fixing part  70  that is fixed to a post body  11  at a base end side thereof. The tool turning motor  60  (i.e., the cover member  69 ) is supported by and fixed to the post body  11  with the support fixing part  70 . The tool turning motor  60  and the cover member  69  are positioned outside the end face  12   b.    
     The distal end side (the end face  12   b  side) of the cover member  69  is fixed to a fixed plate  103 . The fixed plate  103  has a circular shape and is projected from a hole  12   c  formed on the end face  12   b . The fixed plate  103  is fixed to the support part  44  with a bracket  104 . The fixed plate  103  is substantially in contact with the hole  12   c  so as to allow the turret  12  to turn and to prevent, for example, a chip from entering inside the hollow part  12   a.    
     The tool attachment part  15 B is attached to the fixed part  13   a  on the predetermined turret face  13 . When the rotatable tool  14   a  (rotatable tool device T) attached to the tool attachment part  15 B is selected, a rotation shaft  33  of the rotatable tool device T is connected to a tool-rotation transmission shaft  32  and the turn input shaft  80  is connected to the turn transmission shaft  97 . Note that clutch mechanisms  72 ,  105  are respectively configured between the rotation shaft  33  and the tool-rotation transmission shaft  32  and between the turn input shaft  80  and the turn transmission shaft  97 . The clutch mechanisms  72 ,  105  are engaged only when the rotatable tool  14   a  attached to the tool attachment part  15 B is selected. 
     The clutch mechanism  105  includes a groove  97   a  formed at a distal end of the turn transmission shaft  97  and a tenon-shaped projection  80   a  formed at a distal end of the turn input shaft  80 . When the rotatable tool  14   a  is selected by turning the turret  12 , the tenon-shaped projection  80   a  is engaged with (fitted to) the groove  97   a . When the tenon-shaped projection  80   a  is engaged with the groove  97   a , the clutch mechanism  105  becomes in an engaged state. Note that the configuration of the clutch mechanism  72  is identical to that of the earlier embodiment. 
     As described above, in this embodiment, the turn input shaft  80  that is engaged with the turn transmission shaft  97  of the drive-force transmission part  90  is provided so as to be associated with the inner holder  52 . Here, the turn transmission shaft  97  corresponds to drive-force transmission part, and the turn input shaft  80  corresponds to drive-force input part. By fixing the outer holder  50  to the fixed part  13   a , the tool attachment part  15 B is attached to the turret  12 . Accordingly, when the rotatable tool  14   a  held by the tool attachment part  15 B is selected, the turn input shaft  80  is engaged with the turn transmission shaft  97  so as to allow the inner holder  52  to turn. 
     The turret tool post  10   a  according to this embodiment is configured as described above. When the rotatable tool  14   a  on the tool attachment part  15 B is selected by turning the rotatable tool  14   a  to the indexing position, the rotation force is transmitted to the rotatable tool device T from the tool-rotation transmission shaft  32  through the clutch mechanism  72  and the tool-rotation input shaft  33 . The rotatable tool  14   a  is rotated around the shaft thereof by the rotation force transmitted to the rotatable tool device T and then performs cutting process or the like onto a workpiece W. 
     Further, the clutch mechanism  105  is in the engaged state. By rotating the tool turning motor  60 , the turn force is transmitted to the inner holder  52  through the motor shaft  61 , the drive-force transmission part  90 , the clutch mechanism  105 , the turn input shaft  80 , the tool turning drive gear  54 , and the drive-force transmission gear  53 . Since the rotatable tool device T is integrally fixed to the inner holder  52 , the rotatable tool device T is turned on the turret face  13  by the transmitted turn force together with the rotatable tool  14   a . As a result, it becomes possible to perform processing on the workpiece W under a state in which the rotatable tool  14   a  is inclined by a predetermined angle relative to the outer circumferential surface of or edge of the workpiece W. 
     As describe above, in this embodiment, the tool attachment part  15 B is attached to the fixed part  13   a  on the predetermined turret face  13  and the rotatable tool device T is installed on the tool attachment part  15 B. Therefore, the rotatable tool device T itself is turned, and the rotatable tool  14   a  is thereby turned integrally with the rotatable tool device T. 
       FIG. 5  is a schematic cross-sectional view illustrating a vicinity of a turret  12  attached to a turret tool post  10   b  according to an embodiment. As described later, the configuration of the turret  12  of this embodiment is substantially identical to that of the earlier embodiment, except for a tool turning motor  110  provided inside a hollow part  12   a  and an attachment-part transmission shaft  112  attached to a motor shaft  111 . Hence, the detailed description is omitted. 
     As illustrated in  FIG. 5 , the tool turning motor  110  is positioned inside a hollow part  12   a  and is supported by a support part  44  with a bracket  113 . Note that electric lines connected to the tool turning motor  110  are led to a turret tool post  10   b  through a hollow pipe  20  and are connected to a controller (not illustrated). 
     The attachment-part transmission shaft  112  is provided at a distal end side of the motor shaft  111  of the tool turning motor  110 . Between the attachment-part transmission shaft  112  and a turn input shaft  80  provided at the outer holder  50  side, a clutch mechanism  105  is provided. The clutch mechanism  105  connects the attachment-part transmission shaft  112  and the turn input shaft  80  only when a rotatable tool  14   a  is selected by an indexing turn of the turret  12 . Here, the attachment-part transmission shaft  112  may be fixed to the motor shaft  111  by, for example, a pressure welding. 
     The clutch mechanism  105  includes a groove  112   a  formed at a distal end of the attachment-part transmission shaft  112  and a tenon-shaped projection  80   a  formed at a distal end of the turn input shaft  80 . When the rotatable tool  14   a  is selected by turning the turret  12 , the tenon-shaped projection  80   a  is engaged with (fitted to) the groove  112   a . When the tenon-shaped projection  80   a  is engaged with the groove  112   a , the clutch mechanism  105  becomes in an engaged state. Note that the configuration of the clutch mechanism  72  is identical to that of the earlier embodiments. 
     As described above, in this embodiment, the turn input shaft  80  that is engaged with the attachment-part transmission shaft  112  is provided to be associated with an inner holder  52 . Here, the attachment-part transmission shaft  112  corresponds to drive-force transmission part, and the turn input shaft  80  corresponds to drive-force input part. The outer holder  50  is fixed to a fixed part  13   a  and a tool attachment part  15 B is attached to the turret  12 . Accordingly, when the rotatable tool  14   a  held by the tool attachment part  15 B is selected, the turn input shaft  80  is engaged with the attachment-part transmission shaft  112  so as to allow the inner holder  52  to turn. 
     The turret tool post  10   b  according to this embodiment is configured as described above. When the rotatable tool  14   a  on the tool attachment part  15 B is selected by turning the rotatable tool  14   a  to the indexing position, a rotation force is transmitted to a rotatable tool device T from a tool-rotation transmission shaft  32  through the clutch mechanism  72  and a tool-rotation input shaft  33 . The rotatable tool  14   a  is rotated around the shaft thereof by the rotation force transmitted to the rotatable tool device T and then performs cutting process or the like onto a workpiece W. 
     Further, the clutch mechanism  105  is in the engaged state. By rotating the tool turning motor  110 , the turn force is transmitted to the inner holder  52  through the motor shaft  111 , the transmission shaft  112 , the clutch mechanism  105 , the turn input shaft  80 , the tool turning drive gear  54 , and the drive-force transmission gear  53 . Since the rotatable tool device T is integrally fixed to the inner holder  52 , the rotatable tool device T is turned on the turret face  13  by the transmitted turn force together with the rotatable tool  14   a . As a result, it becomes possible to perform processing on the workpiece W under a state in which the rotatable tool  14   a  is inclined by a predetermined angle relative to the outer circumferential surface of or edge of the workpiece W. 
     As describe above, in this embodiment, the tool attachment part  15 B is attached to the fixed part  13   a  on the predetermined turret face  13  and the rotatable tool device T is installed on the tool attachment part  15 B. Therefore, similar to the earlier embodiments, the rotatable tool device T itself is turned, and the rotatable tool  14   a  is thereby turned integrally with the rotatable tool device T. 
     Besides, in this embodiment, the tool turning motor  110  and the transmission shaft  112 , which works as the drive-force transmission part, are provided inside the hollow part  12   a  of the turret  12 . Therefore, it becomes possible to suppress the increase in size of the turret tool post  10   b.    
       FIG. 6  is a schematic cross-sectional view illustrating a vicinity of a turret  12  attached to a turret tool post  10   c  according to an embodiment. As described later, the configuration of the turret  12  of this embodiment is substantially identical to that of the earlier embodiment, except for a tool-attachment part  15 C and a rotatable tool device T. Hence, the detailed description is omitted. 
     Similar to the tool attachment part  15 A, the tool attachment part  15 C of this embodiment is detachably fixed inside a fixed part  13   a  formed on a predetermined turret face  13  (illustrated in  FIG. 1 ) of the turret  12 . 
     As illustrated in  FIG. 6 , a tool turning motor  110  is positioned inside a hollow part  12   a  and is supported by a support part  44  with a bracket  113 . Note that electric lines connected to the tool turning motor  110  are led to a turret tool post  10   c  through a hollow pipe  20  and are connected to a controller (not illustrated). 
     The rotatable tool device T is detachably fixed to the fixed part  13   a  with the tool attachment part  15 C. Here, the rotatable tool device T holds a rotatable tool  14   a  such as a drill and an end mill as the rotatable tool  14   a , and the tool attachment part  15 C is configured with an outer holder  50  and an inner holder  52 . 
     The tool attachment part  15 C includes a turn-force transmission mechanism  120  for transmitting a turn force to the inner holder  52  and a rotation-force transmission mechanism  121  for transmitting a rotation force to the rotatable tool  14   a . An attachment-part transmission shaft  112  is provided at a distal end side of a motor shaft  111  of the tool turning motor  110 . Between the attachment-part transmission shaft  112  and the turn-force transmission mechanism  120 , a first clutch  105  is provided. The first clutch  105  connects the attachment-part transmission shaft  112  and the turn-force transmission mechanism  120  only when the rotatable tool  14   a  is selected by an indexing turn of the turret  12 . The attachment-part transmission shaft  112  may be fixed to the motor shaft  111  by, for example, a screw or a pressure welding. 
     Between the other distal end side (the opposite side to a bevel gear  31 ) of a tool-rotation transmission shaft  32  and the rotation-force transmission mechanism  121 , a second clutch  72  is provided. The second clutch  72  connects the tool-rotation transmission shaft  32  and the rotation-force transmission mechanism  121  only when the rotatable tool  14   a  is selected by the indexing turn of the turret  12 . 
     The rotation-force transmission mechanism  121  includes a rotation-force transmission shaft  122 . The rotation-force transmission shaft  122  is inserted into and rotatably supported by the inner holder  52  with bearings. The inner holder  52  is rotatably (or turnably) supported by the outer holder  50  with bearings. At a distal end part of the rotation-force transmission shaft  122 , a bevel gear  126  is provided. 
     The second clutch  72  includes a groove  32   a  formed at a distal end of the tool-rotation transmission shaft  32  and a tenon-shaped projection  122   a  formed at a distal end of the rotation-force transmission shaft  122 . When the rotatable tool  1   a  is selected by turning the turret  12 , the tenon-shaped projection  122   a  is engaged with (fitted to) the groove  32   a.    
     When the tenon-shaped projection  122   a  is engaged with the groove  32   a , the second clutch  72  becomes in an engaged state such that a rotation force transmitted to the tool-rotation transmission shaft  32  is transmitted to the rotation-force transmission shaft  122 . 
     The turn-force transmission mechanism  120  includes a first turn-force transmission shaft  141  attached with a gear  140 , a second turn-force transmission shaft  143  integrally formed with a gear  142 , a tool turning drive gear  144  attached to the second turn-force transmission shaft  143 , and a cylindrical shaft  146  formed with a drive-force transmission gear  145 . The gear  140  and the gear  142  are engaged, and the tool turning drive gear  144  and the drive-force transmission gear  145  are engaged. 
     The first turn-force transmission shaft  141  is rotatably supported by the outer holder  50  with bearings. The second turn-force transmission shaft  143  is rotatably supported by the outer holder  50  with bearings. The cylindrical shaft  146  is integrally fixed to the inner holder  52  using a connection member  147 . A device body Tc of the rotatable tool device T is detachably and integrally fixed to a distal end side of the inner holder  52  by, for example, a bolt. 
     The rotatable tool device T includes a first rotation-force transmission shaft  123  rotatably supported by the device body Tc with bearings and a second rotation-force transmission shaft  124  rotatably supported by the device body Tc with bearings. The rotatable tool  14   a  is detachably attached to the second rotation-force transmission shaft  124  with a chuck mechanism  125 . 
     The first rotation-force transmission shaft  123  and the second rotation-force transmission shaft  124  are associated with each other through gears  128 ,  129 , which are engaged with each other through other gears (not illustrated). The first rotation-force transmission shaft  123  has a bevel gear  127  at a distal end part thereof. When the device body Tc is fixed to the inner holder  52 , the bevel gear  126  and the bevel gear  127  are engaged to connect the rotation-force transmission shaft  122  and the first rotation-force transmission shaft  123 . The rotation force is transmitted to the rotation-force transmission shaft  122  from the tool-rotation transmission shaft  32  through the second clutch  72 . The rotation force is then transmitted from the rotation-force transmission shaft  122  to the rotatable tool  14   a  through the bevel gears  126 ,  127 , the first rotation-force transmission shaft  123 , the gears  128 ,  129 , and the second rotation-force transmission shaft  124 . 
     The first clutch  105  includes a recessed groove  112   a  and a tenon-shaped projection  141   a . The recessed groove  112   a  is formed at a distal end of the attachment-part transmission shaft  112 , which is provided on the post body  11  side of the turret tool post  10 . The tenon-shaped projection  141   a  is formed at a distal end of the first turn-force transmission shaft  141  of the turn-force transmission mechanism  120  in the tool attachment part  15 C attached to the turret  12  (turret face  13 ), which is disposed on the rotatable tool  14   a  side. With this configuration, when the turret  12  turns and the rotatable tool  14   a  is selected by the indexing turn, the tenon-shaped projection  141   a  is engaged with (fitted to) the groove  112   a . The attachment-part transmission shaft  112  and the tool-rotation transmission shaft  32  are arranged to be substantially in parallel to each other. 
     When the tenon-shaped projection  141   a  is engaged with the groove  112   a , the first clutch  105  becomes in the engaged state. Accordingly, the turn force transmitted from the motor shaft  111  to the attachment-part transmission shaft  112  is transmitted to the first turn-force transmission shaft  141  through the first clutch  105 . The turn force is then transmitted to the inner holder  52  through the first turn-force transmission shaft  141 , the gears  140 ,  142 , the second turn-force transmission shaft  143 , the tool turning drive gear  144 , the drive-force transmission gear  145 , and the cylindrical shaft  146 . The inner holder  52  is turned by the transmitted turn force. That is, by turning the tool attachment part  15 C to turn the inner holder  52 , the rotatable tool device T is turned integrally with the inner holder  52 , and the rotatable tool device T is thereby turned integrally with the rotatable tool  14   a.    
     As described above, in this embodiment, the first turn-force transmission shaft  141  that is engaged with the attachment-part transmission shaft  112  is provided to be associated with an inner holder  52 . Here, the attachment-part transmission shaft  112  corresponds to drive-force transmission part, and the first turn-force transmission shaft  141  corresponds to drive-force input part. Further, in this embodiment, a flange of the inner holder  52  corresponds to the support part to support the rotatable tool  14   a  with the rotatable tool device T. The outer holder  50  is fixed to the fixed part  13   a  and the tool attachment part  15 C is attached to the turret  12 . Accordingly, when the rotatable tool  14   a  held by the tool attachment part  15 C is selected, the first turn-force transmission shaft  141  is engaged with the attachment-part transmission shaft  112  so as to allow the inner holder  52  to turn. 
     The turret tool post  10   c  according to this embodiment is configured as described above. When the rotatable tool  14   a  held by the tool attachment part  15 C using the rotatable tool device T is selected by turning the rotatable tool  14   a  to the indexing position, the second clutch  72  becomes in the engaged state. Accordingly, by rotating the tool-rotating motor  28 , a rotation force of the tool-rotating motor  28  is transmitted to the rotatable tool  14   a  from the tool-rotation transmission shaft  32  through the rotation-force transmission mechanism  121 . The rotatable tool  14   a  is rotated by the transmitted rotation force and then performs cutting process or the like onto a workpiece W. 
     Further, the first clutch  105  is in the engaged state. By rotating the tool turning motor  110 , the rotatable tool  14   a  is turned on the turret face  13  together with the rotatable tool device T through the turn-force transmission mechanism  120 . As a result, it becomes possible to perform processing on the workpiece W under a state in which the rotatable tool  14   a  is inclined by a predetermined angle relative to the outer circumferential surface of or edge of the workpiece W. 
     As described above, in this embodiment, the tool attachment part  15 C is attached to the fixed part  13   a  on the predetermined turret face  13  and the rotatable tool device T is held by the tool attachment part  15 C. Therefore, similar to the preceding embodiments, the rotatable tool device T itself is turned, and the rotatable tool  14   a  is thereby turned integrally with the rotatable tool device T. 
     REFERENCE SIGNS LIST 
       1  Automatic lathe (Machine tool);  2  Main spindle;  3  Main spindle headstock;  10 ,  10   a ,  10   b ,  10   c  Turret tool post;  11  Holder body;  12  Turret;  13  Turret face;  13   a  Fixed part:  14   a  Rotatable tool;  15 A,  15 B,  15 C Tool attachment part;  21  Tool rotation shaft;  23  Turret turning shaft;  32  Tool-rotation transmission shaft;  33  Tool-rotation input shaft;  50  Outer holder;  52  Inner holder;  53 ,  145  Drive-force transmission gear;  54 ,  144  Tool turning drive gear;  60 ,  110  Tool turning motor;  62 ,  90  Drive-force transmission part;  68  Belt;  80  Turn input shaft;  91  Turn shaft;  97 ,  112  Turn transmission shaft; C Main-spindle axis line; W Workpiece; T Rotatable tool device; Ta Flange; Tb Insertion portion