Abstract:
The invention relates to a machine tool comprising feeding system to linearly feed a slide to be fed ( 5 ). Each feed gear comprises a first and a second feed mechanisms provided to be in a parallel manner and spaced apart from each other by a specified interval therebetween, wherein each feed mechanism comprises a linear feed-driving means, a feed-moving body which engages with the feed-driving means and moves along the feed-driving means, and a position sensor to detect positions of the feed-moving body along the feed-driving means. Each feed gear further comprises a first and a second support mechanisms respectively connected to each feed-moving body of the first and the second feed mechanisms with rotatably supporting the slide to be fed ( 5 ), and a controller ( 60 ) for controlling operations of the first and the second feed mechanisms respectively. In addition, at least either of support portions of the first and the second support mechanisms for rotatably supporting the slide to be fed ( 5 ) is provided to be movable in such a direction as separating from the other, rotating the slide to be fed ( 5 ) according to a difference in moving amount of the feed-moving bodies. Since the slide to be fed ( 5 ) is provided to be rotative, even such parts as having complicated surfaces can be easily machined.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a machine tool such as a lathe, a milling machine, a machining center etc. comprising feeding system to linearly feed a tool rest, a tool post, a tool slide, a tool box and a slide to be fed such as a spindle head, a table etc. 
     2. Description of the Prior Art 
     An conventional general machine tool comprises feeding system composed of linear feed-driving means such as a ball screw etc., feed-moving bodies such as a ball nut etc. which engage with the feed-driving means and move along them, and position sensors such as a rotary encoder etc. to detect positions of the feed-moving bodies along the feed-driving means. The feeding system drive above-mentioned tool rest etc. and the slide such as the spindle head, the table etc. to move them linearly. 
     For example, the machining center comprises a table for installing an object to be machined (hereinafter referred to as a work piece) thereto, a spindle which is rotatably supported and can hold a tool at a front end portion thereof, and three pairs of feeding system which relatively move the table and the spindle in the mutually orthogonal three axes directions. Hence, through the relative displacement of the table and the spindle in the above-mentioned three orthogonal axes directions by driving the three pairs of feeding system, a three-dimensional machining can be realized for the work piece put on the table. 
     The above-mentioned three pairs of feeding system are disposed so that the each feed-driving means is mutually orthogonal, the table is driven by the first feed gear provided with the horizontal feed-driving means, and the spindle is driven by the second and the third feeding system whose feed-driving means are mutually orthogonal as well as at right angles to feed-driving means of the first feed gear. Generally, one feed gear is formed of one feed-driving means, and the slide to be fed such as above-mentioned table is driven by such feed gear and also guided by linear guide mechanisms (for example a rolling guide and a sliding guide etc.) arranged at both sides of the feed-driving means, the slide moving along the linear guide mechanisms. 
     There are work pieces not only having the comparatively simple work surfaces such as a horizontal surface and a perpendicular surface but also having complicated surfaces that need complex machining such as an inclined surface and a curved surface. 
     However, in the conventional machine tool comprising above-mentioned feeding system, since the spindle is driven so that it executes a parallel movement in a three-dimensional space with keeping a previously set posture thereof, that is to say, since it is impossible to swing the spindle in such a manner that a spindle center obliquely crosses feed directions of the feeding system, the work piece having above-mentioned complicated surface cannot be machined. 
     For solving this problem, such a machining center as shown in FIG. 6 has been developed. As shown in FIG. 6, a machining center  100  comprises a bed  101 , a pair of columns  102  and  102  respectively erected from both sides of the bed  101 , and a cross beam  103  horizontally linked with upper end portions of the column  102  and  102 . 
     A table  105  which is driven by the first feed gear (not shown) having above-mentioned construction and reciprocally moves in the X-axis direction indicated by an arrow (X) is mounted on the bed  101 , and a saddle  106  which is driven by the second feed gear (not shown) and reciprocally moves in the Y-axis direction indicated by an arrow (Y) is disposed at a front face  103   a  of the cross beam  103 , and a slide  107  which is driven by the third feed gear (not shown) and reciprocally moves in the Z-axis direction indicated by an arrow (Z) is disposed at a front of the saddle  106 . A head holder  108  which is driven by a first rotary feed gear (not shown) comprising a drive motor and a worm gear etc. and rotates in the direction of an arrow A is disposed at a front of the feed slide  107 . A spindle head  111  which is supported by a support shaft  110 , driven by a second rotary feed gear (not shown) comprising a drive motor etc., rotating in the direction of an arrow B is disposed between a pair of support arms  109 ,  109  of the head holder  108 . The spindle head  111  rotatably supports a spindle  112  having a front end portion to hold a tool T and axially rotates the spindle  112  by an appropriate drive means such as a built-in drive motor (not shown) etc. 
     Hence, above-mentioned each feed gear (not shown) and the drive means (not shown) are controlled in their operations by a controller  113 . 
     In the machining center  100  comprising above-mentioned composing elements, the table  105  and the spindle  112  can be relatively moved in the X-axis, Y-axis and Z-axis directions respectively by driving and controlling above-mentioned each feed gear (not shown) and the drive means (not shown) owing to the controller  113 , furthermore, the spindle  112  can swing so that the spindle center thereof obliquely crosses the driving directions of the feeding system (not shown). Thus, the spindle  112  can be linearly and curvilinearly moved in the three-dimensional space. Therefore, the work pieces having the complicated surfaces are continuously machined at a time with being fixed on the table  105 . 
     However, there is another defect as described below in the machining center  100  which enabled above-mentioned complicated machining. 
     The head holder  108  and the spindle head  111  are driven by the rotary feeding system comprising the drive motor and the worm gear etc., rotating in the directions of the arrow A and the arrow B respectively, whereby needing complicated constructions thereof, as a result the size of a mechanism itself becomes large in view of strength thereof. In addition, since the rotary feeding system must be stored in a limited space, they cannot be produced easily, consequently a manufacturing cost is heightened. It is also problem on accuracy that the rotary feeding system using the worm gear etc., have many error factors such as a backlash which disables a precise control of the head holder  108  and the spindle head  111 . 
     It is a general advantage of the present invention to solve above-mentioned problems and to provide an improved machine tool which can linearly move a tool rest etc. and a slide to be fed such as a spindle head, a table etc. and comprises feeding system to rotate the slide so as to obliquely cross the directions of above-mentioned linear motions. A further advantage is to provide a machine tool comprising above-mentioned feeding system to machine work pieces having complicated surfaces. 
     SUMMARY OF THE INVENTION 
     The foregoing advantages are accomplished by the present machine tool that comprises feeding system to linearly feed a slide to be fed. In the machine tool, each feed gear comprises a first and a second feed mechanisms which are provided in parallel manner spaced apart from each other by a specified interval therebetween respectively comprising: a linear feed-driving means, a feed-moving body which engages with the feed-driving means and moves along the feed-driving means and a position sensor to detect positions of the feed-moving body along the feed-driving means, a first and a second support mechanisms which are respectively connected to each feed-moving body of the first and the second feed mechanisms and rotatably support the slide to be fed, and a control means to independently control the feed motions of the first and the second feed mechanisms, wherein at least either of support portions of the first and the second support mechanisms rotatably supporting the slide to be fed is disposed so as to move in such a direction as being separated from the other, and the slide to be fed is rotated on the basis of a difference in moving amount of the feed-moving bodies. 
     According to the present invention, two feed-moving bodies can be synchronously moved by independently controlling the feed motions of the first and the second feed mechanisms, on the other hand, those two feed-moving bodies can be moved in such a manner that there is a difference in moving amount therebetween. For synchronously moving two feed-moving bodies, the slide to be fed can be moved in a parallel manner, while for moving them such that there is a difference in moving amount therebetween, at least either of the support portions of the first and the second support mechanisms moves so as to separate from the other on the basis of the movements of the feed-moving bodies, as a result the slide to be fed rotates within a plane including two feed-driving means, consequently the slide to be fed moves with being rotated in the feeding directions of the first and the second feed mechanisms. 
     As mentioned above, in the present invention, the slide to be fed can be rotated. Therefore, even though a work piece has a complicated surface, it can be easily machined. In addition, since the slide to be fed can be rotated by one feed gear, the structure of the feed gear itself is made simple, consequently there is such an advantage that the machine tool in the present invention can be produced easily in comparison with an conventional one, as a result a manufacturing cost can be lowered. 
     There is another advantage that the support portions in the present invention can be disposed so as to be linearly moved relative to the slide to be fed. Thus, a simple and precise mechanism to move the support portions can be attained. 
     In addition, the feed-driving means in above-mentioned present invention can be composed of a linear motor. The drive means with using the conventional worm gear as described above have many error factors such as a backlash, therefore the slide to be fed cannot be precisely rotated. However, by using the linear motor, such error decreases, whereby the slide to be fed can be precisely rotated. 
     Furthermore, when the slide to be fed is provided with a tool hold mechanism to hold a tool, the tool can be linearly moved in the feeding directions of the feeding system and also can be rotated, whereby it is possible to machine the work piece having the complicated surface such as a curved one. 
     Furthermore, the machine tool in the present invention can comprise a pair of columns disposed in a parallel manner being spaced away from each other by a specified interval therebetween, a cross beam linked with the columns, and a table that is provided under the cross beam and is allowed reciprocating in orthogonal direction of the cross beam, wherein the first and the second feed mechanisms are disposed at a front face of the cross beam, the slide is provided with the tool hold mechanism to rotatably hold the tool, and the tool hold mechanism is movable across the feed-driving means. In such construction, the table and the tool hold mechanism can be linearly moved in two-axial directions of a moving direction of the table and a longitudinal direction of the cross beam both of which are disposed at right angles to each other, also can be linearly moved relative to such a direction as crossing above-mentioned two axes. In addition, the tool hold mechanism can be rotated within the plane including the first and the second feed mechanisms, whereby the work pieces having the complicated surfaces such as the curved ones etc. can be continuously machined at a time with being fixed on the table. Furthermore, when a circular table which can be horizontally rotated is set on the table, it is also possible to continuously machine work pieces having more complicated shapes at a time with being fixed on the table. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view illustrating a preferred machine tool concerning the present invention. 
     FIG. 2 is a greatly enlarged front elevation illustrating a spindle head and a cross beam of the machine tool shown in FIG.  1 . 
     FIG. 3 is a cross-sectional view taken in the direction indicated by the arrow I—I shown in FIG.  2 . 
     FIG. 4 is a cross-sectional view taken in the direction indicated by the arrow II—II shown in FIG.  2 . 
     FIG. 5 is a cross-sectional view taken in the direction indicated by the arrow III—III shown in FIG.  2 . 
     FIG. 6 is a perspective view illustrating an conventional machining center. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Several embodiments of the present invention will hereinafter be described with reference to the installed drawings. 
     As shown in FIG. 1, a machine tool according to the present invention is classified into an elevation type machining center, comprising a bed  2 , a pair of columns  3 ,  3  erected from both sides of the bed  2 , a cross beam  4  horizontally linked with upper end portions of the columns  3 ,  3 , and a controller  60  for controlling operations of after-mentioned feeding system etc. as basic composing elements. 
     A table  8  which is driven by the feeding system (not shown) and reciprocally moves in the X-axis direction indicated by an arrow (X) is mounted on the bed  2 . A circular table  9  which is driven by a rotary feed gear (not shown) comprising a drive motor and a worm gear etc. and rotating in the direction of an arrow C is mounted on the table  8 . 
     As shown in FIG.  2  and FIG. 3, a front of the cross beam  4  is divided into an upper-side plane  4   a  and a lower-side plane  4   b  by means of a concave area  4   c  formed along the longitudinal direction of the front. A first feed mechanism  11  is provided along the upper-side plane  4   a,  while a second feed mechanism  31  is provided along the lower-side plane  4   b.    
     The first feed mechanism  11  comprises a linear magnet plate  12  in which magnetic poles excited to a N-pole and a S-pole are alternately arranged, a linear scale  16  placed along the magnet plate  12 , a pair of guide rails  14 ,  14  arranged along the magnet plate  12  and the linear scale  16  in such a manner as holding them, slide bearings  15 ,  15  which respectively engage with the guide rails  14 ,  14  and move along them, a feed-moving body  18  fixed to the slide bearings  15 ,  15 , a stator  13  fixed to the feed-moving body  18  so as to face the magnet plate  12 , and a detection amplifier  17  fixed to the feed-moving body  18  so as to face the linear scale  16 . 
     The stator  13  constructs the linear motor together with the magnet plate  12 . An electric power is supplied from the controller  60 . Magnetic poles on the stator  13  are excited to a N-pole and a S-pole by means of such electric power. The stator  13  and the feed-moving body  18  joined therewith are guided to the guide rails  14 ,  14  by an absorptive and a repulsive forces generated between the stator  13  and the fixed poles on the magnet plate  12 , moved to the Y 1 -axis direction indicated by an arrow (Y 1 ). A scale on the linear scale  16  is read by the detection amplifier  17 , thus positions of the feed-moving body  18  on the linear scale  16  can be always detected by the detection amplifier  17 . 
     The second feed mechanism  31  has the same construction as that of the first feed mechanism  11 , comprising a magnet plate  32 , a linear scale  36 , a pair of guide rails  34 ,  34 , slide bearings  35 ,  35 , a feed-moving body  38 , a stator  33 , and a detection amplifier  37 . As in the first feed mechanism  11 , when an electric power is supplied to the stator  33  from the controller  60 , an absorptive and a repulsive forces generate between the stator  33  and fixed poles on the magnet plate  32 , whereby the stator  33  and the feed-moving body  38  joined therewith are guided to the guide rails  34  and  34 , moved to the Y 2 -axis direction indicated by an arrow (Y 2 ). Positions of the feed-moving body  38  on the linear scale  36  are always detected by the detection amplifier  37 . 
     As described above, the controller  60  is connected to the stators  13 ,  33  and to the detection amplifiers  17 ,  37 , receiving signals detected by the detection amplifiers  17 ,  37 , controlling the electric powers supplied to the stators  13 ,  33  independently according to the signals, furthermore controlling the movements of the stator  13  and the feed-moving body  18  joined therewith in the Y 1 -axis direction indicated by the arrow (Y 1 ) and the movements of the stator  33  and the feed-moving body  38  joined therewith in the Y 2 -axis direction indicated by the arrow (Y 2 ). 
     As shown in FIG.  4  and FIG. 5, the feed-moving body  18  of the first feed mechanism  11  and the feed-moving body  38  of the second feed mechanism  31  are respectively provided with a first support mechanism  21  and a second support mechanism  41 , wherein the first support mechanism  21  and the second support mechanism  41  rotatably support a spindle head  5  as a slide to be fed. 
     The first support mechanism  21  comprises a support shaft  22  erected from the feed-moving body  18 , a housing  24  which is rotatably connected to the support shaft  22  through a bearing  23 , guide rails  25 ,  25  which guide the housing  24 , and slide bearings  26 ,  26  which respectively engage with the guide rails  25 ,  25 . The housing  24 , the guide rails  25 ,  25 , and the slide bearings  26 ,  26  are arranged in a space  5   e  formed in the spindle head  5  at such a side thereof as facing the feed-moving body  18 . More precisely to say, the guide rails  25 ,  25  are perpendicularly fixed to facing inside walls  5   f,    5   g  of the space  5   e.  The slide bearings  26 ,  26  which respectively engage with the guide rails  25 ,  25  are fixed to outer surfaces  24   a,    24   b  of the housing  24 . According to above-mentioned construction, the spindle head  5  is rotatably supported by the first support mechanism  22 . The support shaft  22 , the bearing  23 , the housing  24 , and the spindle head  5  are in such a condition that they can relatively move. 
     On the other hand, the second support mechanism  41  comprises a support shaft  42  erected from the feed-moving body  38 , and a bearing  43  which is held inside of a hole  5   h  formed in the spindle head  5  and is connected to the support shaft  42 , wherein the spindle head  5  is rotatably supported by the support shaft  42  and the bearing  43 . 
     As described above, a first feed gear  10  is composed of the first feed mechanism  11 , the second feed mechanism  31 , the first support mechanism  21 , the second support mechanism  41 , and the controller  60  which controls the operations of the first feed mechanism  11  and the second feed mechanism  31 . 
     As shown in FIG. 1, FIG. 4, and FIG. 5, a space  5   a  is formed so as to vertically thrust the spindle head  5 . A spindle quill  6  is provided in the space  5   a  so as to move in the Z-axis direction indicated by an arrow (Z) in the direction along the length of the spindle head  5 ) with being driven by the second feed gear  50 . 
     The second feed gear  50  comprises almost same composing elements as the first feed mechanism  11  and the second feed mechanism  31 , comprising a magnet plate  51 , a linear scale  53 , a pair of guide rails  55 ,  55 , slide bearings  56 ,  56 , a stator  52 , and a detection amplifier  54  etc. 
     The pair of guide rails  55 ,  55  are fixed perpendicular to facing inside walls  5   b,    5   c  of the space  5   a.  The slide bearings  56 ,  56  which engage with the guide rails  55 ,  55  are fixed to outer surfaces  6   a,    6   b  of the spindle quill  6  respectively. The spindle quill  6  can be moved in the Z-axis direction indicated by the arrow (Z) with being guided by the guide rails  55 ,  55  as well as slide bearings  56 ,  56 . 
     The magnet plate  51  and the linear scale  53  are fixed parallel to each other and perpendicular to an inside wall  5   d  of the space  5   a.  The stator  52  and the detection amplifier  54  are fixed parallel to each other to an outer surface  6   c  of the spindle quill  6  so that they face the magnet plate  51  and the linear scale  53  respectively. An electric power is supplied to the stator  52  from the controller  60  as in the first feed mechanism  11  and the second feed mechanism  31 , whereby an absorptive and repulsive forces generate between the stator  52  and fixed poles of the magnet plate  51  so as to drive the stator  52  in the Z-axis direction indicated by the arrow (Z), consequently the spindle quill  6  joined with the stator  52  also moves in the Z-axis direction. Positions of the spindle quill  6  on the linear scale  53  are always detected by the detection amplifier  54 . The controller  60  receives signals detected by the detection amplifier  54 , upon which controlling the electric power supplied to the stator  52 , controlling the movements of the stator  52  and the spindle quill  6  joined therewith in the Z-axis direction indicated by the arrow (Z). 
     The spindle quill  6  rotatably supports a spindle  7  that can hold a tool T at a front end portion thereof. The spindle  7  can be axially rotated by a built-in drive motor. 
     The same composing elements as the first feed gear  10  and the second feed gear  50  can be adopted to the feeding system (not shown) for driving the table  8 , while other mechanism composed of a ball screw, a ball nut, and a servo motor etc. can be adopted, too. The feeding system (not shown), the rotary feed gear (not shown) to drive the circular table  9 , and the drive motor to rotate the spindle  7  are also to be controlled in their operations by the controller  60 . The machine tool  1  also comprises a tool changing apparatus (not shown in particular) provided to appropriately change the tool T held by the spindle  7 . 
     An operating condition of the machine tool  1  in this embodiment comprising above-mentioned composing elements is described below with centering on the operation of the first feed gear  10  as a characteristic element. Hence, the spindle head  5  is in such a condition that the longitudinal direction thereof is vertically kept in its initial condition as shown in FIG.  2 . 
     As described above, the controller  60  receives the signals detected by the detection amplifiers  17 ,  37 , controlling the electric powers supplied to the stators  13 ,  33  respectively, controlling the movements of the stator  13  and the feed-moving body  18  joined therewith in the Y 1 -axis direction indicated by the arrow (Y 1 ) as well as the movements of the stator  33  and the feed-moving body  38  joined therewith in the Y 2 -axis direction indicated by the arrow (Y 2 ) respectively. 
     Therefore, the electric powers can be uniformly supplied from the controller  60  to the stators  13 ,  33 . The spindle head  5  connected to the first support mechanism  21  and the second support mechanism  41  is moved parallel to the Y 1 -axis and Y 2 -axis directions with keeping its initial posture as described above when synchronously moving the stators  13 ,  33 . 
     For example, in such a case that the electric power is supplied to the stator  13  so as to keep the position thereof while the electric power is supplied to the stator  33  so as to shift the position thereof and move same in the plus Y 2 -axis direction, the spindle head  5  rotates in the direction of an arrow A then stays in such a condition as shown by alternate long and two short dashes line in FIG.  2 . This is because the spindle head  5  is rotatably supported by the first support mechanism  21  and the second support mechanism  41 . At this time, the spindle head  5  rotates in the direction of the arrow A around the support shaft  42  owing to the structures of the first support mechanism  21  and the second support mechanism  41 . On the other hand, the feed-moving body  18  and the spindle head  5  reciprocally rotate and move relative to the Z-axis, furthermore, the feed-moving body  18  and the feed-moving body  38  separate from each other according to the moving amount of the feed-moving body  38 . This is because the support shaft  22  etc. of the first support mechanism  21  are disposed so as to move in relation to the spindle head  5  in the longitudinal direction thereof (in the Z-axis direction). 
     On the contrary, in the case that the electric power is supplied to the stator  33  so as to keep the position thereof while the electric power is supplied to the stator  13  so as to shift the position thereof and move same in the plus Y 1 -axis direction, the spindle head  5  rotates in reverse owing to the same action as described above. 
     When the electric power is supplied to each of the stator  13  and the stator  33  respectively such that moving rates thereof differ from each other, there is a difference between the moving amounts of the stator  13  and the stator  33  according to the supplied electric powers, whereby the spindle head  5  moves along the Y 1 -axis and the Y 2 -axis then rotates in the direction of the arrow A according to above-mentioned difference in moving amount of the stator  13  and the stator  33 . 
     As mentioned above, the spindle head  5  can be moved parallel to the Y 1 -axis and the Y 2 -axis or can be rotated in the direction of the arrow A, furthermore, such movement and rotation can be simultaneously promoted through the control of the electric powers supplied to the stators  13 ,  33 . 
     In addition, the spindle quill  6  can be moved in the Z-axis direction indicated by the arrow (Z) by appropriately supplying the electric power to the stator  52  of the second feed gear  50 , while the table  8  can be moved in the X-axis direction indicated by the arrow (X) by driving the feeding system (not shown), furthermore the circular table  9  can be rotated in the direction of the arrow C by driving the rotary feed gear (not shown). 
     Thus, in the machine tool  1  in this embodiment, the circular table  9  can be moved in the direction of the arrow C and the X-axis direction, while the tool T can be moved in the Y 1 -axis and Y 2 -axis directions, the arrow A, as well as the Z-axis. Therefore, through the simultaneous driving and controlling of the circular table  9  and the tool T, a work piece and the tool T put on the circular table  9  and fixed thereto can be simultaneously moved relative to the directions of the arrow C, the X-axis, the Y 1 -axis, the Y 2 -axis and the arrow A, as well as the Z-axis. That is to say, the work piece and the tool T can be relatively moved in a three-dimensional space both in a linear and curvilinear manners. Thus, the work pieces can be continuously machined at a time with being fixed on the circular table  9  even though they have complicated surfaces to be machined such as curved ones etc. 
     Since the spindle head  5  is rotated only by the first feed gear  10  which plays a roll of a linear feed gear without using the rotary feed gear such as the drive motor and the worm gear, the structure of the rotary mechanism can be made simple, and besides the feed gear itself can be made compact. Furthermore, the machine tool  1  in this embodiment can be easily produced in comparison with the conventional machining center  100 , therefore there is such an advantage that the manufacturing cost can be decreased. 
     In addition, since the first feed gear is composed of the linear motor, there happen few errors such as a backlash etc. in comparison with the rotary feed gear using the worm gear etc., therefore the spindle head  5  can be precisely rotated, consequently a precise machining is enabled. 
     Moreover, since the support shaft  22  and the housing  24  of the first support mechanism  21  are provided to be guided by the guide rails  25 ,  25  as well as the slide bearings  26 ,  26  so as to relatively move linear to the spindle head  5 , the mechanism for moving the support shaft  22  and the housing  24  can be made comparatively simple and precise. 
     It is to be understood that the characteristic structure of the present invention is not only practiced in the feeding system of the spindle head  5  of the machining center as in this embodiment, but also carried out in the feeding system of the table  8  as well as those of a tool post of a lathe, those of a spindle slide as other machine tools, besides those of a spindle head or a table of a milling machine in other embodiments. 
     Furthermore, in this embodiment, the linear motor comprising the magnet plates  12 ,  32  and the stators  13 ,  33  is used for the first feed gear  10 , while the linear motor comprising the magnet plate  51  and the stator  52  is used for the second feed gear  50 . However, it is to be understood that the invention is not limited in this embodiment. Therefore, the feed mechanism comprising the ball screw, the ball nut, and the servo motor etc. can be used as each feed mechanism of the first feed gear  10  and the second feed gear  50 . 
     Industrial Field of the Invention 
     As described above, the machine tool with respect to the present invention is adaptable to machine parts having complicated surfaces such as curved ones etc.