Patent Publication Number: US-2023143864-A1

Title: Machine tool

Description:
TECHNICAL FIELD 
     The present invention relates to a machine tool for machining an object to be machined using a tool. 
     BACKGROUND ART 
     A machine tool equipped with a cutting unit (a spindle head) having a spindle, and a turning unit provided in the vicinity thereof has been proposed (see, for example, JP 2016-153149 A). In the machine tool disclosed in JP 2016-153149 A, a positional relationship between the cutting unit and the turning unit is fixed in a manner so as not to change. 
     SUMMARY OF THE INVENTION 
     However, in the case of the machine tool disclosed in JP 2016-153149 A, every time that machining is initiated using a cutting tool or a lathe machining tool, it is necessary to measure the distance between a spindle of the cutting unit on which the cutting tool is mounted, and a holder of the turning unit on which the lathe machining tool is mounted, and to set the measured value in the machine tool. 
     Therefore, an object of the present invention is to provide a machine tool that is capable of easily acquiring the distance between a spindle of a first unit and a holder of a second unit. 
     According to an aspect of the present invention, provided is a machine tool including: 
     a first unit including a spindle on which a first tool is mounted; 
     a second unit on which the first tool or a second tool that differs from the first tool is mounted; 
     a support member configured to support the first unit and the second unit; 
     a table configured to support an object to be machined; 
     a relative movement mechanism configured to cause the table to move relative to the support member; 
     a movement control unit configured to control the relative movement mechanism; 
     a relative position detection unit configured to detect a relative position of the table with respect to the support member; and 
     a distance calculation unit configured to calculate a distance between the first unit and the second unit, based on the relative position when the first unit and the table have arrived at a first relative positional relationship, and the relative position when the second unit and the table have arrived at a second relative positional relationship. 
     According to this aspect of the present invention, the distance between the spindle of the first unit and the holder of the second unit can be easily acquired. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a side view showing a machine tool according to an embodiment of the present invention; 
         FIG.  2    is a block diagram showing a configuration of the machine tool according to the embodiment; 
         FIG.  3    is a diagram showing a state of movement of a cutting unit and a turning unit in a left/right direction; 
         FIG.  4    is a diagram showing a state of movement of the cutting unit in an upper/lower direction; 
         FIG.  5    is a flowchart showing a procedure of a distance calculation process; 
         FIG.  6    is a flowchart showing a procedure of a relative position acquisition processing routine; and 
         FIG.  7    is a side view showing a machine tool according to a first exemplary modification. 
     
    
    
     DESCRIPTION OF THE INVENTION 
     A preferred embodiment of the present invention will be presented and described in detail below with reference to the accompanying drawings. 
       FIG.  1    is a side view showing a machine tool  10  according to an embodiment of the present invention. The machine tool  10  serves to carry out machining on an object to be machined. The machine tool  10  may be a machining center, a lathing machine, or a processing machine other than a machining center and a lathing machine. According to the present embodiment, the machine tool  10  is a machining center. 
     In the machine tool  10 , a machine coordinate system is defined which includes an X-axis, a Y-axis, and a Z-axis that intersect each other at right angles. According to the present embodiment, a forward direction (a +X direction) of the X-axis is defined as a right direction (a right side), and a reverse direction (a −X direction) opposite to the forward direction is defined as a left direction (a left side). Further, according to the present embodiment, a forward direction (a +Y direction) of the Y-axis is defined as a front direction (a front side), and a reverse direction (a −Y direction) opposite to the forward direction is defined as a rearward direction (a rear side). Further, according to the present embodiment, a forward direction (a +Z direction) of the Z-axis is defined as an upward direction (an upper side), and a reverse direction (a −Z direction) opposite to the forward direction is defined as a downward direction (a lower side). 
     The machine tool  10  includes a machine main body  12  and a controller  14  for controlling the machine main body  12 . The machine main body  12  includes a bed  20 , a column  22 , a table  24 , a cutting unit  26 , and a turning unit  28 . 
     The bed  20  is a base of the machine tool  10 . The bed  20  is provided on a foundation such as a ground surface and a floor. The column  22  is provided on an installation surface of the bed  20 . Moreover, the installation surface is a surface on an opposite side (an upper side) from a surface on the foundation side (a lower side). 
     The column  22  is a support column for supporting the cutting unit  26  and the turning unit  28 . The column  22  extends toward the upward direction that intersects with the installation surface of the bed  20 . A Z-axis rail  30  that extends along a Z-axis direction (the upper/lower direction) is provided on the column  22 . A support member  32  that supports the cutting unit  26  and the turning unit  28  is connected to the Z-axis rail  30  so as to be capable of moving on the Z-axis rail  30 . 
     The table  24  serves to support the object to be machined. The table  24  is provided closer to the foundation side (the lower side) than the cutting unit  26  and the turning unit  28  are. The table  24  includes a saddle  34 , a direct drive table  36 , and a rotary table  38 . 
     The saddle  34  is movably connected to a Y-axis rail  40  that extends along a Y-axis direction (a front/rear direction). The Y-axis rail  40  is provided on the installation surface of the bed  20 . The direct drive table  36  is movably connected to an X-axis rail  42  that extends along an X-axis direction (the left/right direction). The X-axis rail  42  is provided on an installation surface of the saddle  34 . The rotary table  38  is provided on an installation surface of the direct drive table  36 , and includes a rotating shaft that extends along the Z-axis direction (the upper/lower direction). Moreover, the rotary table  38  may include an inclined portion that causes an installation surface of the rotary table  38  to be inclined. The object to be machined is fixed by a predetermined fixture to the installation surface of the rotary table  38 . 
     According to the present embodiment, a sensor  50  is mounted on the table  24  by fixing the sensor  50  to the installation surface of the rotary table  38 . The sensor  50  is used in order to acquire the distance between the cutting unit  26  and the turning unit  28 . The sensor  50  includes a support rod  52  that extends in the upward direction from the installation surface of the rotary table  38  to the support member  32  side, and a spherical shaped detector  54  disposed on a distal end of the support rod  52 . The detector  54  outputs a signal indicating the presence or absence of contact with an object. 
     The cutting unit  26  is a unit on which a cutting tool is mounted, and is capable of being attached and detached to and from the support member  32 . The cutting unit  26  corresponds to a portion referred to as a spindle head. The cutting unit  26  includes a spindle  26 X, a housing  26 Y through which the spindle  26 X is inserted and which is fixed to the support member  32 , and a bearing (not shown) that rotatably supports the spindle  26 X with respect to the housing  26 Y. The cutting unit  26  may be provided with a turret type automatic changer  44 . 
     The spindle  26 X extends toward the table  24 . At an end part of the spindle  26 X on the table  24  side, an attachment and detachment mechanism (a holder) capable of attaching and detaching the cutting tool is provided. According to the present embodiment, a first object to be detected  56  is mounted on the cutting unit  26  by the first object to be detected  56  being installed on the attachment and detachment mechanism. The first object to be detected  56  serves as a detection target for the sensor  50 , and is used in order to acquire the distance between the cutting unit  26  and the turning unit  28 . 
     The turning unit  28  is a unit on which a lathe machining tool is mounted, and is capable of being attached and detached to and from the support member  32 . The turning unit  28  includes a housing  28 X that is fixed to the support member  32 . An attachment and detachment mechanism (a holder) capable of attaching and detaching the lathe machining tool is provided on a predetermined site on a surface of the housing  28 X on the table  24  side. According to the present embodiment, a second object to be detected  58  is mounted on the turning unit  28  by the second object to be detected  58  being installed on the attachment and detachment mechanism. The second object to be detected  58  is used in order to acquire the distance between the cutting unit  26  and the turning unit  28 . The second object to be detected  58  may be formed with the same shape as the first object to be detected  56 . According to the present embodiment, the second object to be detected  58  has a cylindrical shape, which is the same as the shape of the first object to be detected  56 . 
     The controller  14  includes a cutting control mode and a turning control mode. In the case of the cutting control mode, the controller  14  uses the cutting tool that is mounted on the cutting unit  26 , and carries out a cutting process on an object to be machined that is supported on the table  24 . In this case, in a state in which the rotary table  38  is placed in a non-rotating state and the spindle  26 X is made to rotate, the controller  14  causes one of the table  24  or the cutting unit  26  to move relative to another of the table  24  and the cutting unit  26  in the X-axis direction, the Y-axis direction, or the Z-axis direction. 
     On the other hand, in the case of the turning control mode, the controller  14  uses the lathe machining tool that is mounted on the turning unit  28 , and carries out a turning process on the object to be machined that is supported on the table  24 . In this case, in a state in which the spindle  26 X is placed in a non-rotating state and the rotary table  38  is made to rotate, the controller  14  causes one of the table  24  or the turning unit  28  to move relative to another of the table  24  and the turning unit  28  in the X-axis direction, the Y-axis direction, or the Z-axis direction. 
       FIG.  2    is a block diagram showing a configuration of the machine tool  10  according to the embodiment. The machine main body  12  includes an X-axis relative movement mechanism  60 , a Y-axis relative movement mechanism  62 , and a Z-axis relative movement mechanism  64 . 
     The X-axis relative movement mechanism  60  serves to cause the table  24  to move relative to the support member  32  in the X-axis direction. The X-axis relative movement mechanism  60  includes an X-axis motor, a ball screw that rotates in accordance with driving of the X-axis motor, and a nut that is screw-engaged on the ball screw, and the X-axis relative movement mechanism  60  causes the direct drive table  36  of the table  24  to move relatively in the X-axis direction through the nut. Consequently, the direct drive table  36  moves on the X-axis rail  42 . Moreover, in the case that the X-axis motor rotates clockwise (or counterclockwise), the direct drive table  36  moves relatively in a rightward direction. On the other hand, in the case that the X-axis motor rotates counterclockwise (or clockwise), the direct drive table  36  moves relatively in a leftward direction. 
     The Y-axis relative movement mechanism  62  serves to cause the table  24  to move relative to the support member  32  in the Y-axis direction. The Y-axis relative movement mechanism  62  includes a Y-axis motor, a ball screw that rotates in accordance with driving of the Y-axis motor, and a nut that is screw-engaged on the ball screw, and the Y-axis relative movement mechanism  62  causes the saddle  34  of the table  24  to move relatively in the Y-axis direction through the nut. Consequently, the saddle  34  moves on the Y-axis rail  40 . Moreover, in the case that the Y-axis motor rotates clockwise (or counterclockwise), the saddle  34  moves relatively in the forward direction. On the other hand, in the case that the Y-axis motor rotates counterclockwise (or clockwise), the saddle  34  moves relatively in the rearward direction. 
     The Z-axis relative movement mechanism  64  serves to cause the table  24  to move relative to the support member  32  in the Z-axis direction. The Z-axis relative movement mechanism  64  includes a Z-axis motor, a ball screw that rotates in accordance with driving of the Z-axis motor, and a nut that is screw-engaged on the ball screw, and the Z-axis relative movement mechanism  64  causes the support member  32  to move relatively in the Z-axis direction through the nut. Consequently, the support member  32  moves on the Z-axis rail  30 . Moreover, in the case that the Z-axis motor rotates clockwise (or counterclockwise), the support member  32  moves relatively in the upward direction. On the other hand, in the case that the Z-axis motor rotates counterclockwise (or clockwise), the support member  32  moves relatively in the downward direction. 
     The controller  14  includes a processor  70 , a display unit  72 , an input unit  74 , and a storage unit  76 . The processor  70  serves to process information. As specific examples of the processor  70 , there may be cited a CPU, a GPU, or the like. The display unit  72  serves to display information. As specific examples of the display unit  72 , there may be cited a liquid crystal display, an organic EL display, or the like. The input unit  74  serves to input information. As specific examples of the input unit  74 , there may be cited a keyboard, a mouse, a touch panel, or the like. The storage unit  76  serves to store information. As specific examples of the storage unit  76 , there may be cited a hard disk, a portable memory, or the like. 
     In the storage unit  76 , there are stored a machining program for machining the object to be machined, a distance calculation program for acquiring the distance between the cutting unit  26  and the turning unit  28 , and shape information or the like indicative of the shapes of the first object to be detected  56 , the second object to be detected  58 , and the detector  54 . Moreover, the shape information is input from the input unit  74 . In the case of the present embodiment, the shape information includes a radius (or a diameter) and a height of the first object to be detected  56  and the second object to be detected  58 , which have a cylindrical shape, and a radius (or a diameter) of the detector  54 , which has a spherical shape. 
     In the case of executing the distance calculation program stored in the storage unit  76 , the processor  70  functions as a movement control unit  80 , a relative position detection unit  82 , and a distance calculation unit  84 . In this case, the spindle  26 X and the rotary table  38  do not rotate. 
     The movement control unit  80  serves to control the X-axis relative movement mechanism  60 , the Y-axis relative movement mechanism  62 , or the Z-axis relative movement mechanism  64 . In the case of controlling the X-axis relative movement mechanism  60 , as illustrated in  FIG.  3   , the movement control unit  80  causes the table  24  (the direct drive table  36 ) to move relatively in the rightward direction (or the leftward direction) from a predetermined starting position until the detector  54  of the sensor  50  comes into contact with the first object to be detected  56  of the cutting unit  26 . Further, the movement control unit  80  causes the table  24  (the direct drive table  36 ) to move relatively in the leftward direction (or the rightward direction) from a predetermined starting position until the detector  54  comes into contact with the second object to be detected  58  of the turning unit  28 . 
     Moreover, the movement control unit  80  detects the contact of the detector  54  based on a signal output from the detector  54 . Further, the starting position when the table  24  is moved relatively in a manner so that the detector  54  comes into contact with the first object to be detected  56 , and the starting position when the table  24  is moved relatively in a manner so that the detector  54  comes into contact with the second object to be detected  58  may be the same or may be different from each other. 
     Although not illustrated, the case of controlling the Y-axis relative movement mechanism  62  is the same as the case of controlling the X-axis relative movement mechanism  60 . More specifically, the movement control unit  80  causes the table  24  (or the saddle  34 ) to move relatively in the forward direction or in the rearward direction, in a manner so that the detector  54  comes into contact with each of the first object to be detected  56  and the second object to be detected  58 , from a predetermined starting position until contact of the detector  54  is detected. 
     In the case of controlling the Z-axis relative movement mechanism  64 , as illustrated in  FIG.  4   , the movement control unit  80  causes the support member  32  to move relatively in the downward direction from a predetermined starting position until the detector  54  comes into contact with the first object to be detected  56 . Further, although not illustrated, the movement control unit  80  causes the support member  32  to move in the downward direction from the predetermined starting position until the detector  54  comes into contact with the second object to be detected  58 . Moreover, the starting position when the support member  32  is moved relatively in a manner so that the detector  54  comes into contact with the first object to be detected  56 , and the starting position when the support member  32  is moved relatively in a manner so that the detector  54  comes into contact with the second object to be detected  58  may be the same or may be different from each other. 
     The relative position detection unit  82  detects the relative position of the table  24  with respect to the support member  32 . Based on signals output from the detector  54  of the sensor  50 , the relative position detection unit  82  detects the relative position of the axes in accordance with the control of the movement control unit  80 . 
     More specifically, in the case that the movement control unit  80  controls the X-axis relative movement mechanism  60 , the relative position detection unit  82  detects, based on rotational position information detected by an encoder, the relative position of the table  24  (the direct drive table  36 ) that moves relative to the support member  32 . It should be noted that such an encoder is provided in the X-axis motor of the X-axis relative movement mechanism  60 . 
     On the other hand, in the case that the movement control unit  80  controls the Y-axis relative movement mechanism  62 , the relative position detection unit  82  detects, based on rotational position information detected by an encoder, the relative position of the table  24  (the saddle  34 ) that moves relative to the support member  32 . It should be noted that such an encoder is provided in the Y-axis motor of the Y-axis relative movement mechanism  62 . 
     Further, in the case that the movement control unit  80  controls the Z-axis relative movement mechanism  62 , the relative position detection unit  82  detects, based on rotational position information detected by an encoder, the relative position of the support member  32  that moves relative to the table  24 . It should be noted that such an encoder is provided in the Z-axis motor of the Z-axis relative movement mechanism  64 . 
     The distance calculation unit  84  serves to calculate the distance between the cutting unit  26  and the turning unit  28 . The distance calculation unit  84  calculates the axial distance in accordance with the control of the movement control unit  80  based on the detection result of the relative position detection unit  82  and the shape information stored in the storage unit  76 . 
     More specifically, in the case that the movement control unit  80  controls the X-axis relative movement mechanism  60 , the distance calculation unit  84  calculates a distance DT in the X-axis direction (see  FIG.  3   ) between the center of the first object to be detected  56  of the cutting unit  26 , and the center of the second object to be detected  58  of the turning unit  28 . In this case, the distance calculation unit  84  calculates the distance DT in the X-axis direction on the basis of the starting position when the movement control unit  80  causes the direct drive table  36  to move relatively, the relative position of the direct drive table  36  when the detector  54  comes into contact with each of the first object to be detected  56  and the second object to be detected  58 , and the shape information. 
     Moreover, as noted previously, the shape information includes a radius (or a diameter) and a height of the first object to be detected  56  which has a cylindrical shape, a radius (or a diameter) and a height of the second object to be detected  58  which has a cylindrical shape, and a radius (or a diameter) of the detector  54  which has a spherical shape. Further, the centers of the first object to be detected  56  and the second object to be detected  58  are centers (cylindrical axes) in the Z-axis direction. 
     On the other hand, in the case that the movement control unit  80  controls the Y-axis relative movement mechanism  62 , the distance calculation unit  84  calculates a distance in the Y-axis direction between the center of the first object to be detected  56  of the cutting unit  26 , and the center of the second object to be detected  58  of the turning unit  28 . In this case, the distance calculation unit  84  calculates the distance in the Y-axis direction on the basis of the starting position when the movement control unit  80  causes the saddle  34  to move relatively, the relative position of the saddle  34  when the detector  54  comes into contact with each of the first object to be detected  56  and the second object to be detected  58 , and the shape information. 
     Further, in the case that the movement control unit  80  controls the Z-axis relative movement mechanism  62 , the distance calculation unit  84  calculates a distance in the Z-axis direction between the end surface of the first object to be detected  56  of the cutting unit  26 , and the end surface of the second object to be detected  58  of the turning unit  28 . In this case, the distance calculation unit  84  calculates the distance in the Z-axis direction on the basis of the starting position when the movement control unit  80  causes the support member  32  to move relatively, the relative position of the support member  32  when the detector  54  comes into contact with each of the first object to be detected  56  and the second object to be detected  58 , and the shape information. Moreover, the end surfaces of the first object to be detected  56  and the second object to be detected  58  are end surfaces of the end parts thereof on the table  24  side. 
     Next, a description will be given of the distance calculation process of the controller  14  in which the distance calculation program is executed. Moreover, since the processing content of the distance calculation process for calculating the distance DT in the X-axis direction, the distance calculation process for calculating the distance in the Y-axis direction, and the distance calculation process for calculating the distance in the Z-axis direction are the same, only the distance calculation process for calculating the distance DT in the X-axis direction will be explained in the description of the distance calculation process.  FIG.  5    is a flowchart showing a procedure of the distance calculation process. 
     In step S 1 , the processor  70  executes a relative position acquisition processing routine, to cause the direct drive table  36  to move in a manner so that the detector  54  of the sensor  50  comes into contact with the first object to be detected  56  of the cutting unit  26  or the second object to be detected  58  of the turning unit  28 . In the case that the direct drive table  36  is relatively moved in a manner so that the detector  54  comes into contact with the first object to be detected  56 , the processor  70  acquires the relative position of the direct drive table  36  when the detector  54  is placed in contact with the first object to be detected  56 . On the other hand, in the case that the direct drive table  36  is relatively moved in a manner so that the detector  54  comes into contact with the second object to be detected  58 , the processor  70  acquires the relative position of the direct drive table  36  when the detector  54  is placed in contact with the second object to be detected  58 . When the relative position of the direct drive table  36  at the time when the detector  54  is placed in contact with the first object to be detected  56  or the second object to be detected  58  is acquired, the distance calculation process transitions to step S 2 . 
     In step S 2 , the processor  70  determines whether or not both the relative position of the direct drive table  36  when the detector  54  is placed in contact with the first object to be detected  56 , and the relative position of the direct drive table  36  when the detector  54  is placed in contact with the second object to be detected  58  have been acquired. In this instance, in the case that both of the relative positions have not been acquired, the distance calculation process returns to step S 1 . On the other hand, in the case that both of the relative positions have been acquired, the distance calculation process transitions to step S 3 . 
     In step S 3 , the processor  70  calculates the distance DT in the X-axis direction (see  FIG.  3   ), on the basis of the relative position acquired in step S 1 , the starting position when the direct drive table  36  is relatively moved, and the shape information that is stored in the storage unit  76 . When the distance DT in the X-axis direction is calculated, the distance calculation process comes to an end. 
     Next, a description will be given concerning a relative position acquisition processing routine. It should be noted that only the relative position acquisition processing routine in the case of executing the distance calculation process for calculating the distance DT in the X-axis direction will be explained in the description of the relative position acquisition processing routine.  FIG.  6    is a flowchart showing a procedure of the relative position acquisition processing routine. 
     In step S 11 , the processor  70  appropriately controls each of the relative movement mechanisms  60 ,  62 , and  64 , in a manner so that the cutting unit  26  or the turning unit  28 , and the table  24  are arranged in their initial positions. In a state in which the cutting unit  26  is arranged in the initial position, the first object to be detected  56  mounted on the cutting unit  26  is positioned at a predetermined fixed position. Further, in a state in which the turning unit  28  is arranged in the initial position, the second object to be detected  58  mounted on the turning unit  28  is positioned at a predetermined fixed position. Further, in a state in which the table  24  is arranged in the initial position, the detector  54  of the sensor  50  is positioned at the predetermined starting position. When the cutting unit  26  or the turning unit  28 , and the table  24  have been arranged in their initial positions, the relative position acquisition processing routine transitions to step S 12 . 
     In step S 12 , the processor  70  controls the X-axis relative movement mechanism  60 , in a manner so that the direct drive table  36  moves toward the cutting unit  26  or the turning unit  28 . Consequently, the detector  54  approaches toward the first object to be detected  56  or the second object to be detected  58  which is positioned at the fixed position. When the control of the X-axis relative movement mechanism  60  is initiated, the relative position acquisition processing routine transitions to step S 13 . 
     In step S 13 , based on a signal output from the detector  54 , the processor  70  determines whether or not the first object to be detected  56  or the second object to be detected  58  has come into contact with the detector  54 . 
     In this instance, in the case that the detector  54  has been placed in contact with the first object to be detected  56  or the second object to be detected  58 , the relative position acquisition processing routine transitions to step S 14 . Moreover, the first object to be detected  56  is mounted on the cutting unit  26  that is supported by the support member  32 , and the sensor  50  is mounted on the direct drive table  36  that moves relative to the support member  32 . Therefore, when the sensor  50  has detected the first object to be detected  56  (when the sensor comes into contact with the first object to be detected  56 ), the cutting unit  26  and the direct drive table  36  have arrived at a first relative positional relationship. On the other hand, the second object to be detected  58  is mounted on the turning unit  28  that is supported by the support member  32 , and the sensor  50  is mounted on the direct drive table  36  that moves relative to the support member  32 . Therefore, when the sensor  50  has detected the second object to be detected  58  (when the sensor comes into contact with the second object to be detected  58 ), the turning unit  28  and the direct drive table  36  have arrived at a second relative positional relationship. 
     In step S 14 , the processor  70  stores, in the storage unit  76 , the relative position of the direct drive table  36  when the detector  54  has come into contact with the first object to be detected  56 , or the relative position of the direct drive table  36  when the detector  54  has come into contact with the second object to be detected  58 . When the relative position is stored in the storage unit  76 , the relative position acquisition processing routine transitions to the aforementioned step S 2  (see  FIG.  5   ). 
     On the other hand, in the case that the detector  54  has not been placed in contact with the first object to be detected  56  or the second object to be detected  58 , the relative position acquisition processing routine transitions to step S 15 . In step S 15 , the processor  70  determines whether or not a predetermined period of time has elapsed since the control of the X-axis relative movement mechanism  60  was started. In this instance, in the case that the predetermined time period has not elapsed, the relative position acquisition processing routine returns to step S 13 . On the other hand, in the case that the predetermined time period has elapsed, there is a high possibility that the detector  54  will not come into contact with the first object to be detected  56  or the second object to be detected  58  which is positioned at the fixed position. In this case, the relative position acquisition processing routine transitions to step S 16 . 
     In step S 16 , the processor  70  issues a notification of an abnormality, for example, by displaying, on the display unit  72 , that there is a high possibility that the distance is incapable of being calculated. When the notification of such an abnormality is issued, the relative position acquisition processing routine comes to an end. Moreover, in the case that the relative position acquisition processing routine has come to an end, the distance calculation process also comes to an end. 
     In the foregoing manner, in the machine tool  10  according to the present embodiment, the sensor  50  is mounted on the installation surface of the rotary table  38  that supports the object to be machined. On the other hand, in the cutting unit  26 , the first object to be detected  56  is mounted on the attachment and detachment mechanism (the holder) of the spindle  26 X on which the cutting tool is mounted, and in the turning unit  28 , the second object to be detected  58  is mounted on the attachment and detachment mechanism (the holder) on which the lathe machining tool is mounted. Using the sensor  50 , the first object to be detected  56 , and the second object to be detected  58 , the machine tool  10  calculates the distance DT in the X-axis direction (see  FIG.  3   ), the distance in the Y-axis direction, and the distance in the Z-axis direction between the cutting unit  26  and the turning unit  28 . Consequently, the distance between the spindle  26 X of the cutting unit  26  and the holder of the turning unit  28  can be easily acquired. 
     Moreover, in the case of the present embodiment, both the first object to be detected  56  that is mounted on the cutting unit  26  and the second object to be detected  58  that is mounted on the turning unit  28  can be detected by the single sensor  50 . Further, in the case that the cutting tool is the first object to be detected  56  and the lathe machining tool is the second object to be detected  58 , the distance between the cutting unit  26  and the turning unit  28  can be calculated even without changing the tools. 
     The above-described embodiment may be modified in the following manner. 
     (Exemplary Modification 1) 
       FIG.  7    is a side view showing the machine tool  10  according to a first exemplary modification. In  FIG.  7   , the same reference numerals are applied to configurations that are equivalent to the configurations described in the embodiment. Moreover, in the present exemplary modification, descriptions that overlap or are duplicative of those stated in the embodiment will be omitted. 
     Instead of the sensor  50  according to the embodiment, the machine tool  10  according to the present exemplary modification includes a first sensor  50 A and a second sensor  50 B. Each of the first sensor  50 A and the second sensor  50 B includes the same support rod  52  and the same detector  54  as in the embodiment. 
     The first sensor  50 A is mounted instead of the first object to be detected  56  according to the embodiment. In other words, in the cutting unit  26 , the first sensor  50 A is mounted on the attachment and detachment mechanism (the holder) of the spindle  26 X on which the cutting tool is mounted. On the other hand, the second sensor  50 B is mounted instead of the second object to be detected  58  according to the embodiment. In other words, in the turning unit  28 , the second sensor  50 B is mounted on the attachment and detachment mechanism (the holder) on which the lathe machining tool is mounted. 
     On the other hand, an object to be detected  90  is mounted instead of the sensor  50  according to the embodiment. In other words, the object to be detected  90  is mounted on the installation surface of the rotary table  38  that supports the object to be machined. The object to be detected  90  serves as a detection target for the first sensor  50 A and the second sensor  50 B, and in the same manner as in the embodiment, the object to be detected  90  is used in order to acquire the distance between the cutting unit  26  and the turning unit  28 . The shape of the object to be detected  90  may be a cylindrical shape or a polygonal columnar shape such as a quadrangular prism. Further, the object to be detected  90  may be the rotary table  38 . 
     Also according to the present exemplary modification, by executing the distance calculation process in the same manner as in the embodiment, the distance DT in the X-axis direction (see  FIG.  3   ), the distance in the Y-axis direction, and the distance in the Z-axis direction between the cutting unit  26  and the turning unit  28  can be calculated. Accordingly, in the same manner as in the embodiment, the distance between the spindle  26 X of the cutting unit  26  and the holder of the turning unit  28  can be easily acquired. 
     Moreover, in the case of the present exemplary modification, since the sensor need not be provided on the table  24  side, and further, a predetermined site (for example, the rotary table  38 ) on the table  24  can be used as the object to be detected  90 , the work space of the table  24  is less likely to become restricted. 
     (Exemplary Modification 2) 
     The sensor  50  of the embodiment, or the object to be detected  90  of the first exemplary modification may be mounted on a site of the table  24  other than the installation surface of the rotary table  38 . In such a case, it is necessary to store, in the storage unit  76  beforehand together with the shape information, information indicative of the distance in the X-axis direction, the Y-axis direction, and the Z-axis direction between the mounted position of the sensor  50  or the object to be detected  90  and a reference position on the installation surface of the rotary table  38 . It should be noted that the reference position is a position determined as a reference within a region in which the object to be machined is supported on the installation surface of the rotary table  38 . In the above-described embodiment, the sensor  50  is mounted at the aforementioned reference position. 
     Further, the first object to be detected  56  of the embodiment, or the first sensor  50 A of the first exemplary modification may be mounted on a site of the cutting unit  26  other than the attachment/detachment mechanism (the holder) of the spindle  26 X. Moreover, in such a case, it is necessary to store, in the storage unit  76  beforehand together with the shape information, information indicative of the distance in the X-axis direction, the Y-axis direction, and the Z-axis direction between the mounted position of the first object to be detected  56  or the first sensor  50 A and the attachment and detachment mechanism (the holder). 
     Further, the second object to be detected  58  of the embodiment, or the second sensor  50 B of the first exemplary modification may be mounted on a site of the turning unit  28  other than the attachment/detachment mechanism (the holder). Moreover, in such a case, it is necessary to store, in the storage unit  76  beforehand together with the shape information, information indicative of the distance in the X-axis direction, the Y-axis direction, and the Z-axis direction between the mounted position of the second object to be detected  58  or the second sensor  50 B and the attachment and detachment mechanism (the holder). 
     (Exemplary Modification 3) 
     The sensor  50  of the embodiment, or the first sensor  50 A and the second sensor  50 B of the first exemplary modification are contact sensors, however, the sensors may be laser displacement sensors. Such a laser displacement sensor irradiates a laser from a light emitting unit toward a light receiving unit at one or more predetermined irradiation angles, and detects the arrival of an object based on a shadow generated by the object blocking the laser. Also with such a laser displacement sensor, by executing the distance calculation process in the same manner as in the embodiment, the distance DT in the X-axis direction (see  FIG.  3   ), the distance in the Y-axis direction, and the distance in the Z-axis direction between the cutting unit  26  and the turning unit  28  can be calculated. Accordingly, in the same manner as in the embodiment, the distance between the spindle  26 X of the cutting unit  26  and the holder of the turning unit  28  can be easily acquired. 
     (Exemplary Modification 4) 
     Instead of the cutting tool, the lathe machining tool can be installed on the attachment and detachment mechanism (the holder) provided at the end part of the spindle  26 X on the cutting unit  26 . In the case that the lathe machining tool is installed, machining is implemented in a state in which the spindle  26 X is placed in a non-rotating state. Further, instead of the cutting tool, a tool other than the lathe machining tool can be installed on the attachment and detachment mechanism (the holder). In other words, the cutting unit  26  can be referred to as a first unit which includes the spindle  26 X on which a first tool is mounted. 
     On the other hand, instead of the lathe machining tool, the cutting tool, or a comb-shaped tool with a plurality of cutting edges, or alternatively, a tool other than the cutting tool and the comb-shaped tool can be installed on the attachment and detachment mechanism (the holder) of the turning unit  28 . In other words, the turning unit  28  can be referred to as a second unit on which the first tool that is installed on the first unit or a second tool that differs from the first tool is mounted. 
     The inventions that are capable of being grasped from the above-described embodiments will be described below. 
     The present invention is characterized by the machine tool ( 10 ). The machine tool ( 10 ) includes the first unit ( 26 ) including the spindle ( 26 X) on which the first tool is mounted, the second unit ( 28 ) on which the first tool or the second tool that differs from the first tool is mounted, the support member ( 32 ) that supports the first unit ( 26 ) and the second unit ( 28 ), the table ( 24 ) that supports the object to be machined, the relative movement mechanism ( 60 ,  62 ,  64 ) that causes the table ( 24 ) to move relative to the support member ( 32 ), the movement control unit ( 80 ) that controls the relative movement mechanism ( 60 ,  62 ,  64 ), the relative position detection unit ( 82 ) that detects the relative position of the table ( 24 ) with respect to the support member ( 32 ), and the distance calculation unit ( 84 ) that calculates the distance between the first unit ( 26 ) and the second unit ( 28 ), based on the relative position when the first unit ( 26 ) and the table ( 24 ) have arrived at the first relative positional relationship, and the relative position when the second unit ( 28 ) and the table ( 24 ) have arrived at the second relative positional relationship. In accordance with such features, the distance between the spindle ( 26 X) of the first unit ( 26 ) and the holder of the second unit ( 28 ) can be easily acquired. 
     The distance calculation unit ( 84 ) may calculate the distance based on the relative position when the sensor ( 50 ) that is mounted on the table ( 24 ) has detected the first object to be detected ( 56 ) that is mounted on the first unit ( 26 ), and the relative position when the sensor ( 50 ) has detected the second object to be detected ( 58 ) that is mounted on the second unit ( 28 ). In accordance with such features, both the first object to be detected ( 56 ) and the second object to be detected ( 58 ) can be detected by the single sensor ( 50 ). Further, in the case that the cutting tool is the first object to be detected ( 56 ) and the lathe machining tool is the second object to be detected ( 58 ), the distance between the first unit ( 26 ) and the second unit ( 28 ) can be calculated even without changing the tools. 
     The distance calculation unit ( 84 ) may calculate the distance based on the relative position when the first sensor ( 50 A) that is mounted on the first unit ( 26 ) has detected the object to be detected ( 90 ) that is mounted on the table ( 24 ), and the relative position when the second sensor ( 50 B) that is mounted on the second unit ( 28 ) has detected the object to be detected ( 90 ). In accordance with such features, since the sensor need not be provided on the table ( 24 ) side, and further, a predetermined site on the table ( 24 ) can be used as the object to be detected ( 90 ), the work space of the table ( 24 ) is less likely to become restricted. 
     The support member ( 32 ) may be disposed on the column ( 22 ) that extends from the table ( 24 ) side in the direction intersecting the surface of the table ( 24 ), the second unit ( 28 ) may be arranged between the column ( 22 ) and the first unit ( 26 ), and the distance calculation unit ( 84 ) may calculate the distance in the direction along the surface, and the distance in the direction intersecting the surface. In accordance with such features, the distance between the first unit ( 26 ) and the second unit ( 28 ) can be calculated with high accuracy.