Abstract:
A spindle attachment includes a device body having an attachment surface detachably attached to an end face of a spindle head. Fixed and movable teeth move the body in a direction of an axial line of the spindle to engage the spindle head and the body so as to freely restrict or release rotation of the body with respect to the spindle head. A coil spring urges the body so that the attachment surface is pressed onto the end face of the spindle head with the fixed and movable teeth ready for engagement. A pressure cylinder causes fluid pressure to act on the attachment surface against the spring force to release engagement between the fixed and movable teeth. A key and a key groove transmit rotation of the spindle to the body with the fluid pressure of the cylinder acting on the attachment surface of the device body.

Description:
This application has a priority of Japanese no. 2009-201236 filed Sep. 1, 2009, hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     This invention relates to a spindle attachment device that attaches a cutting device used for a machine tool to a spindle head. 
     In the past, a known example of this kind of device is a device including a device body having an attachment surface detachably attached to an end face of a spindle head and engaging means for engaging the spindle head and the device body by moving the device body in a direction of an axial line of the spindle so as to be able to freely restrict or release rotation of the device body with respect to the spindle head about the axial line thereof, wherein a pull stud is supported on the device body in such a manner as to freely move in an axial direction thereof, wherein when the axial line of the pull stud agrees with the axial line of the spindle, the pull stud is inserted into an axial hole of the spindle and coupled with a drawbar, in which state the device body descends due to its own weight, and wherein in this state, the device body is hung from the spindle head by the pull stud, and the device has transmission means for transmitting rotation of the spindle to the device body in this state (for example, see Japanese Unexamined Patent Publication No. S59-219129). 
     In this conventional device, when the engagement of the engaging means is released and the device body is rotated, the device body is hung from the spindle head, in which state the posture of the rotation thereof is extremely unstable. Therefore, after the device body is rotated, it is difficult to raise the device body and bring the engaging means into engagement. 
     In addition, after the engaging means is brought into engagement, the posture of the device body is unstable during rotation, which may necessitate engagement between the spindle head and the device body. In this case, since the posture of the device body is unstable during rotation, it is necessary to arrange a large engagement gap. However, if a large engagement gap is arranged, there is a possibility that a foreign material may enter into the spindle head from the gap. 
     SUMMARY OF THE INVENTION 
     It is an object of this invention to provide a spindle attachment device capable of rotating a device body in a stable posture when an attachment surface of the device body is attached to or detached from an end face of a spindle head. A spindle attachment device according to this invention includes a device body having an attachment surface detachably attached to an end face of a spindle head, engaging means for moving the device body in a direction of a axial line of a spindle to engage the spindle head and the device body with each other so as to freely restrict or release rotation of the device body with respect to the spindle head about the axial line of the spindle, spring means for urging the device body so that the attachment surface of the device body is pressed onto the end face of the spindle head with the engaging means being ready for engagement, fluid pressure means for causing a fluid pressure to act on the attachment surface of the device body against spring force of the spring means so that the engagement of the engaging means is released, and transmission means for transmitting rotation of the spindle to the device body with the fluid pressure of the fluid pressure means acting on the attachment surface of the device body. 
     In the spindle attachment device according to this invention, when the device body is rotated, the fluid pressure means can cause the fluid pressure to act on the attachment surface of the device body against the spring force of the spring means. 
     Therefore, when the attachment surface of the device body is attached to or detached from the end face of the spindle head, the device body can be rotated in a stable posture. 
     Further, the engaging means may include fixed teeth arranged on a circumference, whose center is the axial line of the spindle, on the end face of the spindle head, and movable teeth arranged on a circumference, having the same diameter as the circumference on which the fixed teeth are formed, on the attachment surface of the device body. In such a case, a desired number of fixed teeth and a desired number of the movable teeth can be arranged appropriately, and it is easy to synchronize the fixed teeth and the movable teeth. 
     Still further, a guide hole may be formed at a center of the circumference, on which the movable teeth are formed, of the attachment surface of the device body, and a pull stud may be inserted into an axial hole of the spindle so as to allow coupling with a drawbar, wherein the pull stud may be inserted into the guide hole in such a manner that the pull stud can move in the direction of the axis thereof, and an annular space may be formed between the peripheral surface of the guide hole and external surface of the pull stud, wherein an inward flange may be arranged on the peripheral surface of the guide hole, and an outward flange may be arranged on the external surface of the pull stud, and wherein the spring means may have a compressed coil spring accommodated in the annular space and transposed between the outward flange and the inward flange. In such a case, the pull stud and the compressed coil spring are effectively used, and the spring force can be effectively used as pressure force exerted by the spring means. 
     Still further, a cylinder may be arranged concentrically with the axial line of the spindle, and wherein the fluid pressure means may have a piston accommodated in the cylinder in such a manner that one end of the piston protrudes from the cylinder so as to be able to come in contact with the attachment surface of the device body. In such a case, the fluid pressure of the fluid pressure means can be effectively exerted on the spindle head. 
     Still further, a movable clamp may be coupled with the protruding end of the piston, and a fixed clamp capable of clamping the movable clamp may be arranged on the attachment surface of the device body, so that according to rotation of the device body about the axial line of the spindle, the fixed clamp can be positioned at an unclamp position and a clamp position with respect to the movable clamp, such that the fixed clamp at the unclamp position can freely move with respect to the movable clamp in the direction of the axis, and the movable clamp can come into engagement from the device body side with the fixed clamp at the clamp position. In such a case, by using the rotation of the device body, the movable clamp and the fixed clamp can be clamped and unclamped. 
     Still further, the transmission means may include a key arranged on the end face of the spindle and a key groove formed on the attachment surface of the device body, and wherein the key can be fitted into the key groove. In such a case, the transmission means can be made with an extremely simple structure. 
     According to this invention, the device body can be forcibly pressed by the pressing means, and when the attachment surface of the device body is attached to or detached from the end face of the spindle head, the device body can be rotated in a stable posture. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a vertical longitudinal sectional view illustrating an attachment device according to this invention; 
         FIGS. 2A and 2B  are horizontal transverse sectional views taken along line II-II of  FIG. 1 ; 
         FIG. 3  is an explanatory diagram illustrating operation of the device; 
         FIG. 4  is an explanatory diagram illustrating operation of the device, subsequent to  FIG. 3 ; 
         FIG. 5  is an explanatory diagram illustrating operation of the device, subsequent to  FIG. 4 ; and 
         FIG. 6  is an explanatory diagram illustrating operation of the device, subsequent to  FIG. 5 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  mainly shows a spindle device  11  of a large vertical complex processing machine capable of performing processing with a milling tool (not shown) directly attached to a spindle, and an attachment device  12  for attaching a cutting tool to the spindle. 
     In this embodiment, the attachment device  12  attaches a turning tool B to the spindle. 
     The spindle device  11  includes a vertical spindle  21  and a spindle head  22  supporting the spindle  21 . 
     The spindle  21  includes a central hole  31 . The lower end section of the central hole  31  is formed with a downward tapered hole  32 . The central hole  31  houses a drawbar  33 . The lower end section of the drawbar  33  is arranged with a collet  34 . Two drive keys  35  are fixed on a circumference, whose center is an axial line of the spindle, on a lower end face of the spindle  21  (see  FIGS. 2A and 2B ). The two drive keys  35  are fixed thereon with a regular interval in a circumferential direction. It should be noted that the spindle  21 , the drawbar  33 , the drive key  35 , and the like are structured as a known spindle that attaches and rotates a known rotational tool, or performs known action for transmitting power to a rotational tool via the drive key and the like when a rotational tool attachment is attached. 
     The lower end face of the spindle head  22  is positioned at a level above the lower end face of the spindle  21 . Above the lower end face of the spindle head  22 , a cylinder  41  having a ring-shaped cross section is formed concentrically with the axial line of the spindle. A tube-shaped piston  42  is inserted into the cylinder  41 . The piston  42  includes a large-diameter upper piston  42   a  housed in the cylinder  41  and a small-diameter lower piston  42   b  continuing from a lower end of the upper piston  42   a . The lower piston  42   b  penetrates through a bottom wall of the cylinder  41 , and protrudes downward from the lower end face of the spindle head  22 . The lower piston  42   b  encircles the spindle  21 . 
     An upper port  43  is arranged in a space above the upper piston  42   a , and a lower port  44  is arranged in a space below within the cylinder  41 . Each of the upper port  43  and the lower port  44  penetrates through the cylinder. 
     Many fixed teeth  45  are formed downward on an outer side of the lower piston  42   b  in a radial direction on the lower end face of the spindle head  22 . On the lower end face of the lower piston  42   b , a movable clamp  46  in a horizontal ring shape is fixed concentrically with the axial line of the spindle. 
     The attachment device  12  has a device body  51  having a turning tool B protruding in the radial direction of the axial line of the spindle. 
     A top face of the device body  51  is formed with an upward recessed section  52  accommodating the lower end section of the spindle  21  and the movable clamp  46 . A guide tube  53  is arranged in the center of the bottom surface of the recessed section  52 . The guide tube  53  is inserted into the tapered hole  32 , and the exterior surface of the guide tube  53  is formed in an upward tapered shape. A cylindrical guide hole  54  having a bottom is formed on an inner surface of the guide tube  53 . A pull stud  55  is held in the guide hole  54 . A radial direction protrusion  55   a  sandwiched by the collet  34  is formed at an upper end section of the pull stud  55 . A vertical rod-shaped guide rod  55   b  is arranged on a lower half of the pull stud  55 . The vertical rod-shaped guide rod  55   b  is inserted into the guide hole  54  so that the vertical rod-shaped guide rod  55   b  can freely slide upward and downward. 
     A vertical cylindrical space  56  is formed between the peripheral surface of the guide hole  54  and the outer surface of the guide rod  55   b . Aninwardflange  57  is arranged inproximity to the upper end of the peripheral surface of the guide hole  54 . An outward flange  58  is arranged on a lower end section of the outer surface of the guide rod  55   b . A compressed coil spring  59  is accommodated within the annular space  56  in such a manner that the compressed coil spring  59  is vertically sandwiched by the inward flange  57  and the outward flange  58 . On the outside of the guide tube  53 , two key grooves  61  are formed on the bottom surface of the recessed section  52 . The drive keys  35  are respectively inserted into the two key grooves  61 . 
     On the outer edge of the top face of the device body  51 , many movable teeth  62  are formed upward so as to face the fixed teeth  45 . 
     A ring-shaped fixing clamp  63  is arranged at a slightly inner side of the movable teeth  62  on the peripheral surface of the recessed section  52 . The ring-shaped fixing clamp  63  is arranged at a low level such that the ring-shaped fixing clamp  63  is positioned at a level below the movable clamp  46 . 
       FIGS. 2A and 2B  show a relationship of the phases among the fixed teeth  45 , the movable teeth  62 , the movable clamp  46 , and the fixed clamp  63 . The movable teeth  62  are aligned in one row with a regular pitch θ on a circumference, whose center is the axial line of the spindle, in a circumferential direction thereof. Although the fixed teeth  45  are not shown in the figures, the fixed teeth  45  have the same structure as the movable teeth  62  but are oppositely oriented in the vertical direction. 
     On the outer edge of the movable clamp  46 , many outward claws  71  are arranged in a circumferential direction thereof with a regular pitch  20 . On the inner edge of the movable clamp  63 , many inward claws  72  are arranged in a circumferential direction thereof with a pitch  20  that is the same pitch as the pitch  20  of the outward claws  71 . The pitch  20  of the outward claws  71  and the inward claws  72  is twice the pitch θ of the movable teeth  62 . 
     In  FIG. 2A , the fixed teeth  45  and the movable teeth  62  can engage with each other in the direction of the axial line of the spindle. One outward claw  71  is positioned between two adjacent inward claws  72 . In this state, when the movable clamp  46  is moved with respect to the fixed clamp  63  in the direction of the axial line of the spindle, one outward claw  71  can pass between two inward claws  72 . Accordingly, the fixed clamp  63  and the movable clamp  46  do not clamp. In other words, the movable clamp  46  is positioned at an unclamp position. 
     The state shown in  FIG. 2A  is changed to the state shown in  FIG. 2B , when the device body  51  is rotated and the fixed clamp  63  is rotated by the pitch θ of the movable teeth  62 . Even in this state, the fixed teeth  45  and the movable teeth  62  can engage with each other, but the fixed clamp  63  and the movable clamp  46  are overlapped in the direction of the axial line of the spindle. When the movable clamp  46  moves with respect to the fixed clamp  63  in the direction of the axial line of the spindle, the inward claws  72  and the outward claws  71  clamp each other. The movable clamp  46  is positioned at a clamp position. 
     With reference to  FIGS. 3 to 6 , attachment operation of the attachment device  12  will be described. 
     The device body  51  is conveyed to a place below the spindle device  11  by a tool replacement apparatus (not shown), and is thereafter moved upward by an upward stroke.  FIG. 3  illustrates the device body  51  immediately before the device body  51  stops ascending at the uppermost position in the upward stroke. 
     The drawbar  33  is positioned at the lowermost position of the upward/downward stroke. The collet  34  is opened. Pressurized oil is supplied to the lower port  44 , and the piston  42  is positioned at the uppermost position of the upward/downward stroke thereof. On the other hand, the pull stud  55  is pulled into the guide tube  53  by force of the spring  59 . The fixed clamp  63  is positioned at a level below the movable clamp  46 . The phases of the fixed teeth  45  and the movable teeth  62  are such that they can engage with each other, and the movable clamp  46  is positioned at the unclamp position. 
     Then, as shown in  FIG. 4 , the tool replacement apparatus further moves the device body  51  upward to raise the device body  51  to the uppermost position. The fixed teeth  45  and the movable teeth  62  engage each other. The movable clamp  46  is positioned at a level below the fixed clamp  63 . There is a space between the bottom surface of the recessed section  52  of the device body  51  and the lower surface of the movable clamp  46 . 
     The guide tube  53  is inserted into the tapered hole  32 . The drawbar  33  is raised, and the collet  34  is closed. Accordingly, the collet  34  sandwiches the protrusion  55   a  of the pull stud  55 , which prevents the pull stud  55  from descending. The keys  35  are inserted into the key grooves  61 . 
     When the lower port  44  is opened to supply pressurized oil to the upper port  43 , the piston  42  descends as shown in  FIG. 5 . The movable clamp  46  as well as the piston  42  descends. Accordingly, the descending movable clamp  46  comes in contact with and presses the bottom surface of the recessed section  52  of the device body  51 . The device body  51  descends against the force of the spring  59 . The pull stud  55  is pulled out of the guide tube  53 . The engagement between the fixed teeth  45  and the movable teeth  62  are disengaged. 
     Then, when the spindle  21  is rotated, the rotation thereof is transmitted to the device body  51  via the keys  35  and the key grooves  61 . While the movable clamp  46  presses the bottom surface of the recessed section  52  of the device body  51 , the device body  51  is rotated by the pitch θ of the movable teeth  62 . The movable clamp  46  is placed at the clamp position. 
     At the last, the upper port  43  is opened to supply pressurized oil to the lower port  44 , so that the piston  42  ascends as shown in  FIG. 6 . Accordingly, the fixed clamp  63  and the movable clamp  46  clamp each other, and the fluid pressure acting on the piston  42  is transmitted to the device body  51 . This pressure binds the engaging state between the fixed teeth  45  and the movable teeth  62 . Therefore, processing can be performed with the turning tool B. 
     In the state shown in  FIG. 6 , there is a gap between the peripheral surface of the tapered hole  32  of the spindle  21  and the outer surface of the guide tube  53 . If, arguendo, there were no gap, the both surfaces would interfere with each other, and the fluid pressure might not be sufficiently transmitted to the fixed teeth  45  and the movable teeth  62 . 
     The spindle attachment device according to this invention is suitable for attaching a cutting device used for a machine tool to the spindle head.