JP2005299773A - Feed screw unit and stage device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform rough moving travel at high speed and minute moving travel by high resolution, miniaturize a feed screw unit, and achieve high precision of movement precision. <P>SOLUTION: This feed screw unit 4 has a screw shaft 11 forming a screw channel 10 at the outer periphery, a nut 12 movable in the axial direction of the screw shaft 11 while screw-fitted into the screw channel 10, a first driving motor 13 for rotating the screw shaft 11 around axis through a first bearing part 17a, a second driving motor 14 for rotating the nut 12 around axis through a second bearing part 20a, a control part for controlling operation of the first driving motor 13 and the second driving motor 14, respectively, and a rotation amount adjusting means 15 for adjusting rotation of the screw shaft 11 and the nut 12 to reduce either of the minimum travel amount for moving the screw shaft 11 by rotating it by the first driving motor 13 and the minimum travel amount for moving the nut 12 by rotating it by the second driving motor 14 to such extent that either is smaller than the other. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a feed screw unit and a stage apparatus including the same.

  A table feed apparatus that moves a table roughly and finely using a feed screw such as a ball screw is required to increase the moving speed and feed resolution simultaneously. Various types of such table feeders are provided, and one of them is a combination of two types of ball screw shafts with different leads, one for coarse feed (high speed) and the other for A moving table used for fine movement feeding (high resolution) is known (see, for example, Patent Document 1).

  Similarly to the moving table described in Patent Document 1, FIGS. 11 to 14 show an example in which two types of ball screw shafts having different leads are combined.

  The fine movement coarse movement table 100 shown in FIGS. 11 to 14 coarsely feeds the base 101 and the table 103 movable on the base 101 via the linear guide 102 including the rail 102a and the block 102b. A coarse motion ball screw unit 104 and a fine motion ball screw unit 105 for finely feeding the table 103 are provided. The coarse motion ball screw unit 104 and the fine motion ball screw unit 105 are arranged in parallel between the base 101 and the table 103.

  As shown in FIGS. 12 and 13, the coarse motion ball screw unit 104 includes a coarse motion servo motor 110 and a coarse motion ball screw connected to the rotary shaft of the coarse motion servo motor 110 via a coarse motion coupling 111. The shaft 112 has a coarse motion ball screw nut 113 screwed into a ball screw groove formed on the outer periphery of the coarse motion ball screw shaft 112 via a plurality of balls.

  The coarse motion ball screw shaft 112, the ball and the coarse motion ball screw nut 113 function as a coarse motion ball screw.

  The coarse motion servo motor 110 is fixed to the base 101 via a bracket. Similarly, the coarse motion ball screw shaft 112 can also rotate on the base 101 via a coarse motion support block 114 having a coarse motion support bearing 114a. It is fixed to.

  As shown in FIGS. 12 and 14, the fine movement ball screw unit 105 includes a fine movement servo motor 120 and a fine movement coupling 121 on the rotation shaft of the fine movement servo motor 120, as in the coarse movement ball screw unit 104. A fine-motion ball screw shaft 122 connected through a plurality of balls, and a fine-motion ball screw nut 123 screwed into a ball screw groove formed on the outer periphery of the fine-motion ball screw shaft 122 via a plurality of balls. Yes.

  The fine movement ball screw shaft 122, the ball, and the fine movement ball screw nut 123 function as a fine movement ball screw. The fine movement ball screw shaft 122 has a smaller lead than the coarse movement ball screw shaft 112.

  The fine movement ball screw shaft 122 is rotatably fixed to a fine movement support block 124 having a fine movement support bearing 124a. The coarse motion ball screw nut 113 is rotatably connected to the fine motion support block 124, and the fine motion servo motor 120 is also fixed. The fine movement support block 124 is movably connected to the base 101 via a fine movement linear guide 125 including a rail 125a and a block 125b. The fine movement ball screw nut 123 is rotatably connected to the lower surface of the table 103.

  When the table 103 is coarsely fed by the fine movement coarse movement table 100 configured in this way, first, the coarse movement servomotor 110 is driven in a state where the fine movement servomotor 120 is stopped, so that the coarse movement ball screw shaft is driven. 112 is rotated. As a result, the coarse motion ball screw nut 113 moves in the axial direction of the coarse motion ball screw shaft 112. At this time, since the fine movement support block 124 is connected to the coarse movement ball screw shaft 112, the table 103 can be coarsely moved along with the movement of the coarse movement ball screw nut 113.

  Next, when the table 103 is coarsely moved by a predetermined distance and then finely fed, the fine movement servomotor 120 is driven while the coarse movement servomotor 110 is stopped to move the fine movement ball. The screw shaft 122 is rotated. Since the fine movement ball screw nut 123 is moved by the rotation of the fine movement ball screw shaft 122, the table 103 can be finely moved.

  As described above, by using the coarse motion ball screw unit 104 and the fine motion ball screw unit 105 having different leads, the table 103 can be moved roughly and finely.

  Further, in the fine movement coarse movement table 100 described above, the coarse movement ball screw unit 104 and the fine movement ball screw unit 105 have been described as being arranged in parallel. For example, as shown in FIGS. A configuration in which the screw unit 104 and the fine adjustment ball screw unit 105 are arranged in a column is also known. When the coarse motion ball screw unit 104 and the fine motion ball screw unit 105 are arranged in a column, the fine motion linear guide 125 is attached to the table 103 side.

Further, as one of the other table feeding devices, there is also known a coarse and fine ball screw in which a feed screw has a double structure, that is, a ball screw nut further formed with ball screw grooves having different leads on the outer periphery of the ball screw nut (for example, Patent Document 2). Also known is a feed mechanism of a table device using a differential screw mechanism in which ball screw grooves having different leads are formed in one ball screw (see, for example, Patent Document 3).
Japanese Patent Laid-Open No. 2001-322046 (paragraph numbers 0023-0064, FIGS. 1-8) Japanese Patent Laid-Open No. 9-324843 (paragraph numbers 0011-0025, FIGS. 1 to 3) Japanese Utility Model Publication No. 62-27257 (pages 1 to 4)

  However, in the moving table described in Patent Document 1 and the conventional coarse / fine movement table 100 shown in FIGS. 11 to 18, two types of ball screw units, a coarse movement ball screw unit 104 and a fine movement ball screw unit 105, are used. Therefore, it is generally difficult to reduce the size of the ball screw shaft as compared with the case where one ball screw shaft is used. That is, as shown in FIGS. 11 to 14, in the case of the parallel arrangement, the horizontal width of the table becomes large, so it is difficult to reduce the size, and in the case of the vertical arrangement as shown in FIGS. Then, since the height dimension becomes large, downsizing is difficult.

  In particular, in the case of parallel arrangement, each ball screw unit cannot be arranged at the center of the linear guide 102. Further, in the case of the tandem arrangement, the ball screw units cannot be arranged at the same height as the linear guide 102. In either case, when the table 103 is moved, a place away from the center of the two linear guides 102 is driven, so a moment load or the like is generated, and the posture displacement of the table 103 is likely to occur. It was difficult to accurately move the. That is, the straightness of the table 103 was inferior.

  Further, the coarse / fine ball screw described in Patent Document 2 requires the formation of ball screw grooves having different leads on the inner and outer circumferences of the ball screw nut, so that the structure is complicated and time is required for production. In addition, it was not easy to produce.

  Furthermore, the feed mechanism of the table device described in Patent Document 3 also requires the formation of two types of ball screw grooves with different leads on one ball screw shaft, so that the structure is complicated as in the case of the coarse and fine ball screw. It takes time to produce. In addition, when the table is moved coarsely and finely, feed errors (manufacturing errors) of both leads are added, so it is difficult to increase the resolution.

  The present invention has been made in view of such circumstances, and its purpose is to enable coarse movement at high speed and fine movement at high resolution, as well as miniaturization and high accuracy of movement. It is providing the feed screw unit which can aim at, and a stage apparatus provided with the same.

  The present invention provides the following means in order to solve the above problems.

  The feed screw unit of the present invention includes a screw shaft having a thread groove formed on the outer periphery, a nut movable in the axial direction of the screw shaft in a state of being screwed into the screw groove, and the screw shaft. A first drive motor that rotates about a shaft through a bearing portion; a second drive motor that rotates the nut around the shaft through a second bearing portion; the first drive motor; and A control unit for controlling the operation of each of the second drive motors, and a minimum movement amount that the screw shaft is rotated by the first drive motor or the nut is rotated by the second drive motor. Rotation amount adjusting means for adjusting the rotation of the screw shaft and the nut so that either one of the minimum moving amounts to move is smaller than the other.

  In the feed screw unit according to the present invention, when the first drive motor is actuated while the second drive motor is stopped by the control unit, the screw shaft rotates via the first bearing unit. Thus, the nut can be moved in the axial direction of the screw shaft by a distance corresponding to the thread groove (distance corresponding to the lead). Further, when the second drive motor is operated while the first drive motor is stopped by the control unit, the nut rotates through the second bearing portion, so that the nut is threaded in the axial direction of the screw shaft. Can be moved by a distance corresponding to the distance (a distance corresponding to the lead).

  At this time, when the rotation of the nut and the screw shaft is adjusted by the rotation amount adjusting means so that the minimum movement amount of the nut is smaller than the minimum movement amount of the screw shaft, for example, the first drive motor By rotating the screw shaft, the nut can be coarsely moved at high speed. Further, the nut can be finely moved with high resolution by rotating the nut with the second drive motor. When the rotation amount adjusting means is adjusted so that the minimum movement amount of the screw shaft is smaller than the minimum movement amount of the nut, the nut is finely moved by operating the first drive motor, and the second The nut can be coarsely moved by operating the drive motor.

  In this way, by rotating the screw shaft and the nut with both drive motors, it is possible to easily perform the respective movement operations while clearly distinguishing the coarse movement and the fine movement. As a result, coarse movement at high speed and fine movement at high resolution can be performed, and high speed and high resolution can be achieved simultaneously. In particular, unlike the conventional case, it is not necessary to form two types of screw grooves with different leads on one screw shaft, that is, the same lead can be used with a common screw shaft and nut, and therefore the influence of screw manufacturing errors. Can be reduced as much as possible.

  In addition, since it is not necessary to use two screw shafts as in the prior art, it is possible to reduce the size (simplification of the structure) and to facilitate manufacturing and reduce manufacturing costs. It is also possible to perform a differential operation with one screw shaft and one lead by rotating both the drive motors by the control unit and simultaneously rotating the screw shaft and the nut.

  The feed screw unit of the present invention is characterized in that, in the feed screw unit of the present invention, the screw shaft and the nut are screwed together via a plurality of balls to constitute a ball screw. is there.

  In the feed screw unit according to the present invention, since the ball screw can be used, the screw shaft and the nut can be finely moved and coarsely moved with higher accuracy.

  In the feed screw unit of the present invention, the first drive motor and the second drive motor are disposed on one end side and the other end side of the screw shaft, respectively. The rotation centers of both drive motors are arranged so as to be aligned on the same axis as the rotation center of the screw shaft.

  In the feed screw unit according to the present invention, since the rotation center of the screw shaft and the nut and the rotation center of both drive motors are on the same axis, the screw shaft and the nut can be smoothly rotated around the shaft with high accuracy. And the influence on high speed and high resolution can be reduced as much as possible. Therefore, it is possible to improve the motion accuracy. Moreover, the rotational force of both drive motors can be directly transmitted to the screw shaft and the nut, and the rotational efficiency is good.

  Moreover, the feed screw unit of the present invention is the above-described feed screw unit of the present invention, wherein the second drive motor is a hollow motor configured in a cylindrical shape along the axial direction, and the screw shaft is It is arranged so that it can be inserted into and removed from the hollow motor.

  In the feed screw unit according to the present invention, since the screw shaft can be inserted into and removed from the hollow motor, the hollow motor can be disposed compactly in a state of being closer to the first drive motor, and further miniaturization can be achieved. be able to.

  In the feed screw unit of the present invention, in the feed screw unit of the present invention, the rotation amount adjusting means is connected to the rotation shaft of either the first drive motor or the second drive motor. And a speed reducer that adjusts the amount of rotation of the rotating shaft.

  In the feed screw unit according to the present invention, the minimum rotation amount of the screw shaft or the nut rotated by the first drive motor or the second drive motor is easily adjusted to a desired rotation amount using a speed reducer. can do. That is, it is easy to change the minimum resolution of the screw shaft or nut that is moved by the both drive motors.

  Further, the table device of the present invention comprises any one of the feed screw units of the present invention, a base that rotatably supports the screw shaft, a nut that rotatably supports the nut, and a movement of the nut relative to the base. And a table movable in the direction.

  In the table device according to the present invention, by operating the first drive motor or the second drive motor, the table can be coarsely moved at high speed via the nut, and finely moved with high resolution. be able to. In addition, the entire table device can be reduced in size and weight.

  The table device of the present invention includes a pair of table guides arranged along the moving direction between the table and the base in the table device of the present invention to guide the table, and the screw shaft Is arranged at the center of the pair of table guides.

  In the table device according to the present invention, since the force from the nut is transmitted to the pair of table guides with equal force, the design can be made in accordance with the principle of the narrow guide. Thereby, the table can be smoothly moved in a state in which the posture displacement is suppressed, and the straightness motion accuracy can be improved. Therefore, it is possible to improve the motion accuracy.

  The table device of the present invention is the table device of the present invention described above, wherein the height of the guide surface center of the pair of table guides and the lower surface of the base, the axis of the screw shaft, and the lower surface of the base The height is the same distance.

  In the table device according to the present invention, since the height of the axis of the screw shaft and the center of the guide surface is the same in the height direction from the lower surface of the base, the table in a state in which the moment in the height direction is eliminated. Can be moved. Therefore, the table can be smoothly moved in a state in which the posture displacement is further suppressed, and the straightness motion accuracy can be further improved to improve the motion accuracy.

  According to the feed screw unit and the table device of the present invention, the nut and the table can be easily coarsely moved at a high speed or finely moved at a high resolution, so that a high speed and a high resolution can be achieved simultaneously. . In particular, since the same lead can be used with a common screw shaft and nut, the influence of screw manufacturing errors can be minimized, and higher resolution can be achieved. In addition, since it is not necessary to use two ball screw shafts as in the prior art, it is possible to reduce the size, and to facilitate manufacturing and reduce manufacturing costs.

  Hereinafter, a first embodiment of a feed screw unit and a table device according to the present invention will be described with reference to FIGS. 1 to 5.

  As shown in FIGS. 1 to 5, the table device 1 of the present invention is capable of coarsely feeding and finely feeding a base 2 placed horizontally, a table 3 movable on the base 2, and the table 3. A ball screw unit (feed screw unit) 4 is provided.

  As shown in FIG. 3, the base 2 is formed in a rectangular shape in a top view extending in one direction (left and right direction with respect to the paper surface), and a recess having an upper opening in a central portion along the one direction. 2a is formed. That is, as shown in FIG. 1, the base 2 is formed in a substantially U-shaped cross-sectional view with the opening facing upward. In addition, a pair of guide rails 5 extending in the one direction are fixed to the upper surface of the protrusion 2b sandwiching the recess 2a.

  As shown in FIG. 3, the table 3 moves in the one direction, and is formed in a rectangular shape in a top view like the base 2. That is, it is formed in a rectangular shape extending in the moving direction (one direction) and the lateral width direction orthogonal to the moving direction. Further, as shown in FIG. 1, the table 3 is formed in a central portion along the moving direction by forming a concave portion 3 a having an opening below and having a substantially U shape in a sectional view. Thereby, between the base 2 and the table 3, the space part 6 which consists of both recessed parts 2a and 3a is formed. In addition, a pair of guide blocks 7 that are movable while being fitted to the pair of guide rails 5 are fixed to the lower surfaces of both projecting portions 3b that sandwich the recess 3a. The guide block 7 and the guide rail 5 function as a pair of linear guides (table guides) 8. That is, the pair of linear guides 8 is arranged along one direction between the base 2 and the table 3 to guide the table 3. Thereby, the table 3 can move with respect to the base 2 via the linear guide 8.

  In the present embodiment, as shown in FIG. 3, the guide blocks 7 are arranged on the one-side protrusion 3b with a total of four guide blocks 7 with a predetermined interval. However, the guide block 7 is not limited to two on one side.

  As shown in FIG. 4, the ball screw unit 4 includes a ball screw shaft (screw shaft) 11 having a ball screw groove (screw groove) 10 formed on the outer periphery, and a plurality of balls not shown in the ball screw groove 10. A ball screw nut (nut) 12 that can be moved in the axial direction of the ball screw shaft 11 and a coarse servo motor (first drive motor) that rotates the ball screw shaft 11 about its axis. ) 13, a fine-motion servomotor (second drive motor) 14 that rotates the ball screw nut 12 about its axis, a control unit (not shown) that controls the operations of the servomotors 13 and 14, and the ball screw nut 12 Is the minimum amount of movement that is moved by being rotated by the servo motor 14 for fine movement, and the minimum amount of movement by which the ball screw shaft 11 is moved by being rotated by the servo motor 13 for coarse movement Remote and a rotation amount adjusting means 15 for adjusting the rotation of the ball screw nut 12 so as to reduce.

  The ball screw shaft 11, the ball and the ball screw nut 12 function as a ball screw.

  In the ball screw unit 4 of the present embodiment, the coarse servo motor 13 and the fine servo motor 14 are arranged on one end side and the other end side of the ball screw shaft 11, respectively. The rotation center is arranged in the space portion 6 described above in a state where the rotation center is aligned on the same axis as the rotation center of the ball screw shaft 11. As a result, the moving direction of the ball screw nut 12 matches the moving direction of the table 3. At this time, the ball screw shaft 11 and the ball screw nut 12 are arranged at the center of the pair of linear guides 8 as shown in FIG. 1, and the bottom surface of the base 2 and the shaft core of the ball screw shaft 11 are arranged. The distance (height) and the distance (height) between the lower surface of the base 2 and the center of the guide surface of the linear guide 8 are configured to be the same distance.

  As shown in FIG. 4, the coarse movement servomotor 13 is fixed on the base 2 with the rotating shaft 13 a facing one end of the ball screw shaft 11. The ball screw shaft 11 is connected to a rotary shaft 13a of a coarse servo motor 13 via a coarse motion coupling 16, and has a coarse motion support block 17a having a coarse motion support bearing (first bearing) 17a. It is rotatably supported on the base 2 via The ball screw shaft 11 has the ball screw groove 10 formed on the outer periphery thereof with a predetermined lead in a range of a region where the coarse motion support block 17 is projected.

  An intermediate shaft 18 is coupled to the ball screw nut 12 screwed into the ball screw groove 10 so as to cover the outer peripheral surface of the ball screw nut 12. The intermediate shaft 18 is formed so as to extend to the other end side of the ball screw shaft 11 along the axial direction of the ball screw shaft 11, the ball screw nut 12 side is a large diameter portion 18a, and the tip, that is, The other end side is a reduced diameter portion 18b having a diameter smaller than that of the large diameter portion 18a. Further, a ball screw hole 18 c into which the ball screw shaft 11 can be inserted and removed is formed in the intermediate shaft 18 along the axial direction of the ball screw shaft 11. Thereby, for example, when the ball screw nut 12 is moved in the axial direction of the ball screw shaft 11 by the rotation of the ball screw shaft 11, the ball screw nut 12 is inserted into and removed from the ball screw hole 18c. Along with the movement, the intermediate shaft 18 also moves in the axial direction.

  The front end side of the intermediate shaft 18 is connected to the rotating shaft 14a of the fine movement servomotor 14 via a fine movement coupling 19. Accordingly, the ball screw nut 12 can be rotated via the intermediate shaft 18 by driving the fine movement servomotor 14. The intermediate shaft 18 is rotatably supported by the fine movement support bearing (second bearing portion) 20a of the fine movement support block 20 fixed to the lower surface of the table 3 at the reduced diameter portion 18b. The fine movement support bearing 20a is connected by a fastening nut 21 attached to the outer peripheral surface on the front end side of the intermediate shaft 18 so as to be sandwiched between the fastening nut 21 and the large-diameter portion 18a of the intermediate shaft 18. . As a result, the fine movement support block 20 and the table 3 can be moved along with the movement of the intermediate shaft 18. That is, the table 3 rotatably supports the ball screw nut 12 via the fine movement support block 20 and the intermediate shaft 18 and moves in the moving direction of the ball screw nut 12. The fine movement servo motor 14 is fixed to the fine movement support block 20.

  The fine movement servomotor 14 is connected to the rotation shaft 14a and transmits the rotation speed transmitted to the ball screw nut 12 to, for example, about 1/5 slower than the rotation speed transmitted from the coarse movement servomotor 13 to the ball screw shaft 11. A speed reducer 22 that adjusts the amount of rotation is built in. Accordingly, the fine movement servomotor 14 functions as a fine movement feed motor. The speed reducer 22 functions as the rotation amount adjusting means 15.

  Moreover, as shown in FIG. 2, the linear sensor scale 23 is attached to the table 3 along the moving direction on one side surface. In addition, a linear sensor 24 is attached to the base 2 so as to face the linear sensor scale 23, and the measurement value is sent to a control unit (not shown). Thereby, the movement amount of the table 3 with respect to the base 2 can be measured.

  The case where the table 3 and the ball screw unit 4 configured in this manner are used to move the table 3 coarsely (coarsely feed) and finely move (finely feed) will be described.

  When coarse feed is performed, the coarse servo motor 13 is driven to rotate the rotating shaft 13a while the fine servo motor 14 is stopped using a stall torque or the like by the control unit. This rotational force is transmitted to the ball screw shaft 11 through the coarse motion coupling 16, and the ball screw shaft 11 rotates about the axis. On the other hand, since the rotation of the ball screw nut 12 is restricted by the stop of the fine movement servo motor 14, the ball screw nut 12 is coarsely moved at high speed in the axial direction of the ball screw shaft 11 as the ball screw shaft 11 rotates. I do. At this time, the ball screw shaft 11 is inserted into and removed from the ball screw hole 18c of the intermediate shaft 18 in accordance with the relative movement with the ball screw nut 12, so that the movement of the ball screw nut 12 is not hindered.

When the ball screw nut 12 is moved, the intermediate shaft 18 is also coarsely moved along with the movement, and is further finely moved between the large diameter portion 18a and the fastening nut 21 and connected to the reduced diameter portion 18b. The support block 20 for fine movement and the servomotor 14 for fine movement simultaneously perform coarse movement. Thereby, the table 3 can be coarsely moved in the axial direction (moving direction) of the ball screw shaft 11. At this time, the rotational center of the coarse servo motor 13 and the rotational center of the ball screw shaft 11 and the ball screw nut 12 are aligned on the same axis, so that the rotational force of the coarse servo motor 13 can be efficiently applied to the ball screw shaft. 11 and the ball screw shaft 11 can be smoothly rotated around the shaft with high accuracy. Therefore, the influence on the coarse movement can be reduced as much as possible, and the table 3 can be coarsely moved in a short time.
When the control unit confirms that the table 3 has moved by a predetermined movement amount based on the measurement result sent from the linear sensor 24, the control unit stops the coarse movement and performs fine movement feeding of the table 3. That is, the control unit drives the fine movement servo motor 14 to rotate the rotating shaft 14a in a state where the coarse movement servo motor 13 is stopped using a stall torque or the like. This rotational force is transmitted to the ball screw nut 12 via the intermediate shaft 18 to rotate the ball screw nut 12 about the axis. At this time, since the rotation of the ball screw shaft 11 is restricted by the stop of the coarse servo motor 13, the ball screw nut 12 is finely moved in the axial direction.

  As in the case of the coarse movement described above, the intermediate shaft 18 also finely moves with the movement of the ball screw nut 12, and the fine movement support block 20 and the fine movement servomotor 14 simultaneously finely move. . Thereby, the table 3 can be finely moved with high resolution toward the axial direction of the ball screw shaft 11. At this time, since the rotation center of the fine movement servomotor 14 and the rotation center of the ball screw nut 12 are aligned on the same axis, the rotational force of the fine movement servomotor 14 is efficiently transmitted to the ball screw nut 12. The ball screw nut 12 can be rotated around the axis smoothly with high accuracy. Therefore, the influence on the fine movement can be reduced as much as possible, and the table 3 can be finely moved with high resolution.

  Since the common ball screw shaft 11 and the ball screw nut 12 can be used for the above-described coarse movement and fine movement of the table 3, the size (structure of the structure) can be reduced as compared with the case where two conventional ball screws are used. Simplification) as well as facilitating the production and reducing the production cost. Further, since the lead of the same ball screw groove 10 can be used, the influence of screw manufacturing errors can be suppressed as much as possible.

  Further, since the ball screw shaft 11 and the ball screw nut 12 are arranged at the center of the pair of linear guides 8, the propulsive force from the ball screw nut 12 is transmitted to the pair of linear guides 8 with an equal force (action). To do. As a result, it is possible to design in accordance with the principle of the narrow guide, and when the table 3 is moved coarsely and finely, it can be smoothly moved with the posture displacement suppressed, and the straightness motion accuracy can be improved. it can. Therefore, the motion accuracy of the table 3 can be improved.

  Furthermore, since the center of the guide surface of the guide rail 5 and the axis of the ball screw shaft 11 are the same in the height direction, a moment in the height direction is generated when the table 3 is moved coarsely and finely. Also from the absence, it is possible to suppress the posture displacement of the table 3 and improve the straightness motion accuracy.

  In addition, by using the speed reducer 22, the minimum rotation amount of the ball screw nut 12 can be easily adjusted to a desired rotation amount. That is, the minimum resolution of the ball screw nut 12 that is moved by the fine movement servomotor 13 can be easily changed. In addition, since servo motors having a common rotational speed can be used as the coarse motion servo motor 13 and the fine motion servo motor 14, even if a failure or the like occurs, replacement and the like are easy, and the maintenance cost is also suppressed. be able to.

  As described above, according to the table device 1 and the ball screw unit 4 of the present embodiment, the table 3 can be easily moved coarsely at high speed or finely moved with high resolution. Can be achieved simultaneously. In particular, since the same lead can be used with the common ball screw shaft 11 and the ball screw nut 12, the influence of screw manufacturing errors can be minimized and higher resolution can be achieved. Further, unlike the prior art, since it is not necessary to use two ball screw shafts, it is possible to reduce the size, and to facilitate manufacturing and reduce manufacturing costs.

  Next, a second embodiment of the table device and the feed screw unit according to the present invention will be described with reference to FIGS. Note that in the second embodiment, identical symbols are assigned to configurations identical to those in the first embodiment and descriptions thereof are omitted.

  The difference between the second embodiment and the first embodiment is that, in the first embodiment, the coarse movement servomotor 13 and the fine movement servomotor 14 have the same shape, whereas the second embodiment is different from the second embodiment. In the table apparatus 30, the servo motor for fine movement includes a ball screw unit (feed screw unit) 32 that is a hollow motor 31 configured in a cylindrical shape along the axial direction of the ball screw shaft 11. It is the point arranged so that insertion / extraction in the hollow motor 31 is possible.

  That is, as shown in FIG. 9, the hollow motor 31 has the intermediate shaft 18 through the connecting intermediate member 33 so that the hollow hole 31a formed in a size capable of inserting and removing the ball screw shaft 11 faces the axial direction. Is attached to the tip (the other end of the ball screw shaft 11). Thus, the hollow motor 31 is configured integrally with the fine movement support block 20.

  According to the table device 30 having the ball screw unit 32 configured in this way, the ball screw shaft 11 can be inserted into and removed from the hollow hole 31a when the table 3 is coarsely moved and finely moved. Can be arranged closer to the coarse servo motor 13. Accordingly, the length of the ball screw shaft 11 in the axial direction, that is, the length of the table 3 in the feed direction can be shortened, so that a more compact configuration can be achieved and the size can be reduced.

  The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

  For example, in the first and second embodiments described above, the table is coarsely moved by rotating the ball screw shaft by the coarse servo motor, and the ball screw nut is rotated by the fine servo motor (hollow motor). However, the present invention is not limited to this, and the table may be coarsely moved by rotating the ball screw nut, and the table may be finely moved by rotating the ball screw shaft. . In this case, the rotation amount adjusting means may be adjusted so that the minimum movement amount of the ball screw shaft is smaller than the minimum movement amount of the ball screw nut. That is, a speed reducer may be connected to the rotation axis of the ball screw shaft.

  The rotation amount adjusting means uses a speed reducer, but is not limited to this. The rotation amount of the servo motor is set so that the minimum movement amount of one of the ball screw shaft or the ball screw nut is smaller than the other minimum movement amount. Any method can be used as long as it is adjusted. For example, the method of adjusting the minimum resolution by using the electronic gear settings of the servo driver that controls the servo motor, adjusting the rotation amount by setting each servo motor to a different electronic gear ratio, For example, the motor encoder may be mounted with different minimum resolutions. Further, drive motors having different rotational speeds may be used. In addition to a servo motor, a numerically controllable motor such as a stepping motor may be used.

  Furthermore, although the ball screw is taken as an example of the feed screw, the present invention is not limited to the ball screw, and any movement screw that can use a triangular screw, trapezoidal screw, static pressure screw or the like as the feed screw may be used.

  In addition, when the table 3 is moved coarsely and finely, the control unit stops one of the servo motors using the stall torque. However, the present invention is not limited to this. For example, the drive of the servo motor is stopped. A brake may be provided, and the operation of the brake may be controlled by the control unit.

  Further, when the table 3 is moved coarsely and finely, either one of the servomotors is stopped by the control unit. For example, when the table 3 is coarsely moved, both servomotors are driven. You may comprise. By doing so, a differential operation can be performed, so that the table can be coarsely moved at a higher speed.

  In addition, although the linear guide is provided between the table and the base, the linear guide may not be used. For example, a static pressure guide using a fluid such as oil or air may be used.

It is a front view which shows 1st Embodiment of the ball screw unit and table apparatus which concern on this invention. It is a side view of the table apparatus shown in FIG. It is a top view of the table apparatus shown in FIG. It is a cross-sectional arrow AA figure of the table apparatus shown in FIG. It is a cross-sectional arrow BB figure of the table apparatus shown in FIG. It is a front view which shows 2nd Embodiment of the ball screw unit and table apparatus which concern on this invention. It is a side view of the table apparatus shown in FIG. It is a top view of the table apparatus shown in FIG. It is a cross-sectional arrow CC view of the table apparatus shown in FIG. It is a cross-sectional arrow DD figure of the table apparatus shown in FIG. It is the front view which showed an example of the conventional ball screw unit and a table apparatus. It is a cross-sectional arrow EE figure of the table apparatus shown in FIG. It is a cross-sectional arrow FF figure of the table apparatus shown in FIG. It is a cross-sectional arrow GG figure of the table apparatus shown in FIG. It is the front view which showed the other example of the conventional ball screw unit and the table apparatus. It is a cross-sectional arrow HH figure of the table apparatus shown in FIG. It is a cross-sectional arrow JJ figure of the table apparatus shown in FIG. It is a cross-sectional arrow KK figure of the table apparatus shown in FIG.

Explanation of symbols

1, 30 Table device 2 Base 3 Table 4, 32 Ball screw unit (feed screw unit)
8 Table guide (linear guide)
10 Ball screw groove (thread groove)
11 Ball screw shaft (screw shaft)
12 Ball screw nut (nut)
13 Coarse servo motor (first drive motor)
14 Servo motor for fine movement (second drive motor)
15 Rotation amount adjustment means 17a Coarse movement support bearing (first bearing)
20a Support bearing for fine movement (second bearing part)
22 Reducer 31 Hollow motor

Claims (8)

A screw shaft having a thread groove formed on the outer periphery;
A nut movable in the axial direction of the screw shaft in a state of being screwed into the screw groove;
A first drive motor that rotates the screw shaft about a shaft through a first bearing;
A second drive motor for rotating the nut around the axis via a second bearing portion;
A control unit for controlling the operation of each of the first drive motor and the second drive motor;
Either the minimum movement amount that the screw shaft is moved by being rotated by the first drive motor or the minimum movement amount that is moved by the nut being rotated by the second drive motor, is set to be more than the other. A feed screw unit comprising rotation amount adjusting means for adjusting rotation of the screw shaft and the nut so as to be reduced. In the lead screw unit according to claim 1,
The feed screw unit, wherein the screw shaft and the nut are screwed together via a plurality of balls to form a ball screw. In the lead screw unit according to claim 1 or 2,
The first drive motor and the second drive motor are disposed on one end side and the other end side of the screw shaft, respectively, and the rotation centers of both drive motors are on the same axis as the rotation center of the screw shaft. Lead screw unit characterized by being arranged side by side. In the lead screw unit according to claim 3,
The second drive motor is a hollow motor configured in a cylindrical shape along the axial direction;
The feed screw unit, wherein the screw shaft is detachably disposed in the hollow motor. In the lead screw unit according to any one of claims 1 to 4,
The rotation amount adjusting means includes a speed reducer that is connected to the rotation shaft of either the first drive motor or the second drive motor and adjusts the rotation amount of the rotation shaft. Screw unit. A lead screw unit according to any one of claims 1 to 5,
A base that rotatably supports the screw shaft;
A table device comprising: a table that rotatably supports the nut and is movable in a moving direction of the nut relative to the base. The table apparatus according to claim 6, wherein
A pair of table guides arranged along the moving direction between the table and the base to guide the table;
The table device characterized in that the screw shaft is arranged at the center of the pair of table guides. The table apparatus according to claim 7, wherein
The table device characterized in that the height of the center of the guide surface of the pair of table guides and the lower surface of the base and the height of the axis of the screw shaft and the lower surface of the base are the same distance.

Images