JP4992182B2 - Axial fine movement device with rotating mechanism - Google Patents

Description

The present invention relates to an axial fine movement device with a rotation mechanism that performs high-precision fine positioning within a long stroke range.

  Conventional positioning devices perform coarse and fine motion operations by combining a coarse motion mechanism that drives a long stroke range with a ball screw device in which a screw shaft and nut are screwed together with a fine motion mechanism that uses a piezoelectric actuator. A piezoelectric actuator is placed between the coarse motion table and the fine motion table, or between the nut of the ball screw device and the moving table, and the position of the base and the fine moving table or the moving table is changed by the expansion and contraction of the piezoelectric actuator. Nanometer level high-precision fine positioning is performed within the range (for example, see Non-Patent Document 1).

In addition, the backlash between the screw shaft of the ball screw device and the nut is eliminated by a coil spring, and a piezoelectric actuator disposed between one end of the screw shaft and the base is expanded and contracted, so that the moving base fixed to the nut There are some which perform fine positioning of the axial position of the screw shaft (for example, see Non-Patent Document 2).
The piezoelectric actuator used in such a case is generally a laminated piezoelectric actuator, but the laminated piezoelectric actuator has sufficient strength and rigidity with respect to the load in the compression direction, but it can handle the load in the tensile direction. On the other hand, the mechanical properties of the material of the piezoelectric actuator and the strength due to the adhesive strength between the layers are extremely weak, and even a small tensile load may be damaged.

In order to solve this problem, a piezoelectric actuator manufacturer (for example, Physik Instrument, Germany) presses the output shaft 101 of the piezoelectric actuator 100 with a spring 102 as shown in FIG. It is recommended that the piezoelectric actuator 100 has a structure in which a compressive load acts even when it acts.
Jiro Otsuka et al., “Precision positioning mechanism”, 2nd edition, Industrial Research Co., Ltd., August 15, 2001, p. 118-201 Jiro Otsuka and two others, “Development of a small displacement sensor with 1 nm resolution and a compact ultra-precision positioning device”, Journal of Precision Engineering, Japan Society for Precision Engineering, October 5, 2003, Vol. 69, No. 10, p. . 1431

  However, in Non-Patent Document 1 and Non-Patent Document 2 described above, a piezoelectric actuator is disposed between a nut of a ball screw device and a moving table, or between one end of a screw shaft and a base, and both ends thereof are nuts. Since it is directly attached to the moving table, there is a problem that when the positioning device is moved left and right, a load acts in the left-right direction, and a tensile load acts on the piezoelectric actuator and the piezoelectric actuator may be damaged.

  Further, when the structure shown in FIG. 11 is applied to the positioning devices of Non-Patent Document 1 and Non-Patent Document 2, the tensile load acting on the piezoelectric actuator of the positioning device is a compressive load due to a spring disposed on the output shaft. Although the predetermined positioning can be performed for the movement at a low speed in a smaller range, the spring supporting the pulling direction is a relatively soft spring for the high-speed response. The rigidity of the motor is reduced and its natural frequency is lowered, and there is a problem that if a fine movement operation is performed at high speed, oscillation may occur and high-speed response may not be performed.

This is because the positioning device has a two-axis overlapping structure that moves in a two-dimensional direction (X-Y direction), or a result of mounting parts such as a mounting jig on the moving table even if it is one axis. This is particularly important when the mass of the moving table is increased.
Furthermore, since the strength of the piezoelectric actuator is weak not only with respect to the tensile load but also with respect to the radial load, the tip of the output shaft of the piezoelectric actuator is made spherical so that no radial load or moment force acts on the piezoelectric actuator. Although recommended, the piezoelectric actuator used in the fine movement mechanism must be directly attached to other members, and depending on the attachment accuracy, there is a problem that it may be damaged early due to the radial load or moment force. .

Furthermore, if the piezoelectric actuator is to be accurately placed on the coaxial axis of the screw shaft or nut of the ball screw device, in the structure shown in Non-Patent Document 1 and Non-Patent Document 2, the centering operation becomes complicated, There is a problem that it is difficult to assemble the positioning device.
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a fine movement mechanism that can perform a fine movement operation with high response and can prevent damage to a piezoelectric actuator.

In order to solve the above-mentioned problem, the present invention provides an axial fine movement device with a rotating mechanism that fits two rolling bearing devices that are arranged opposite to each other and applied with a preload, and the outer peripheral surface of each outer ring of the rolling bearing device. A housing having an inner peripheral surface, an axis having an outer peripheral surface with which an inner peripheral surface of each inner ring of the rolling bearing device is fitted, and an externally disposed one side in the axial direction of the two rolling bearing devices. A piezoelectric actuator that expands and contracts in the axial direction in accordance with an applied voltage, and a cover that presses an end face of the piezoelectric actuator is provided on one side of the housing by fastening the housing with fastening means, In the rolling bearing device on one side in the axial direction of the two rolling bearing devices, the outer ring is constrained in the axial direction via the piezoelectric actuator to the housing fitted with the outer peripheral surface thereof. The inner ring is axially restrained and attached to the fitted shaft, and in the rolling bearing device on the other axial side of the two rolling bearing devices, the inner ring is restrained in the axial direction on the housing fitted with the outer ring. The inner ring is attached to the fitted shaft while being restrained in the axial direction, and the axial distance between the outer rings of the two rolling bearing devices to which the preload is applied is determined by the preload accompanying the expansion and contraction of the piezoelectric actuator. The relative displacement amount in the axial direction of the outer ring and the inner ring of the constrained rolling bearing device on the other side is the relative movement amount of the shaft and the housing. One of the housings is fixed in the axial direction, and the piezoelectric actuator is energized when rotation of the rolling bearing device is stopped .

As a result, the present invention allows the rolling bearing device arranged opposite to function as a spring member having a very high rigidity, and allows the piezoelectric actuator to perform a coarse motion operation and a fine motion operation while constantly applying a compressive load. the combination of a spring member in the compression direction with high rigidity and high rigidity, it is possible to maintain high rigidity of the entire positioning device, a high speed, the can be determined promptly by using an stable micromotion operation of the high-response, tensile piezoelectric actuator The effect that the generation | occurrence | production of the damage by a load can be prevented is acquired.

Embodiments of an axial fine movement mechanism with a rotation mechanism (an axial fine movement apparatus with a rotation mechanism) and a positioning apparatus using the same according to the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view showing an axial fine movement mechanism with a rotation mechanism according to the first embodiment, FIG. 2 is a plan view showing the positioning device according to the first embodiment, and FIG. 3 is a side view showing the positioning device according to the first embodiment. FIG. 4 and FIG. 4 are explanatory diagrams seen from the side showing the control device of the first embodiment.
2, 3, and 4, reference numeral 1 denotes a positioning device.
Reference numeral 2 denotes a linear guide mechanism, which is a linear guide device composed of a bowl-shaped slider 4 assembled to a rail 3 via a rolling element. The rail 3 is installed on a base 5 of the positioning device 1 and is a slider. The movable table 6 of the positioning device 1 is attached to the movable table mounting surface 4a of the four by a bolt or the like. The linear guide mechanism 2 of the present embodiment includes two rails 3 installed on both sides of the screw shaft 11 on the base 5 in parallel with the longitudinal direction (referred to as the axial direction) of the screw shaft 11 of the coarse movement mechanism 10 and each rail 3. And four sliders 4 in total.

  The coarse movement mechanism 10 includes a plurality of illustrated shaft raceway grooves 11 a formed on the outer peripheral surface of the screw shaft 11 and nut raceway grooves (not shown) facing the shaft raceway groove 11 a formed on the inner peripheral surface of the nut 12. A ball screw device 13 as a feed screw device screwed through a non-ball, a drive motor 14 disposed at one end of the screw shaft 11 and capable of rotating in the forward and reverse directions such as a stepping motor installed on the base 5, A coupling 15 that connects the drive motor 14 and the screw shaft 11 and a support bearing 16 such as a deep groove ball bearing that is disposed on the other end of the screw shaft 11 and is installed on the base 5 are configured.

The nut 12 of the coarse movement mechanism 10 of the present embodiment is fixed to the moving base 6, and is screwed to the screw shaft 11 with no play in the axial direction by preloading with an oversized ball or the like. The support bearing 16 supports the screw shaft 11 in a rotatable manner and supports the other end of the screw shaft 11 so as to be movable by play in the axial direction.
Reference numeral 17 denotes a position sensor, which is fixed to the movable base 6 and detects fine irregularities formed at equal intervals on a scale 18 installed in parallel with the screw shaft 11 on the base 5 and controls the output signal to be described later. A function of outputting to the device 45 is provided. Using this output signal, the control device 45 measures the relative movement amount of the moving table 6 and the base 5.

In FIG. 1, 20a and 20b are angular contact ball bearings as rolling bearing devices, and are formed on the outer ring raceways 22a and 22b formed on the inner peripheral surfaces of the outer rings 21a and 21b and on the outer peripheral surfaces of the inner rings 23a and 23b. A plurality of balls 25a and 25b serving as rolling elements disposed between the inner ring raceways 24a and 24b.
Angular contact ball bearings 20a and 20b are opposed to each other as a front combination, and the inner peripheral surfaces of the inner rings 23a and 23b are fitted to the outer peripheral surface of the fitting shaft 26 formed on the drive motor 14 side of the screw shaft 11, and the outer ring The outer peripheral surfaces of 21a and 21b are fitted to the inner peripheral surface of the housing 27 fixed to the base 5 with bolts or the like, and support the screw shaft 11 together with the support bearing 16 so as to be rotatable.

Reference numeral 29 denotes an inner ring locking portion, which is a large diameter portion having a diameter substantially equal to the outer diameter of the inner rings 23a and 23b formed between the shaft raceway groove 11a of the screw shaft 11 and the fitting shaft 26, One side surface of the inner ring 23a is locked.
Reference numeral 30 denotes an inner ring spacer, which is a cylindrical member having an outer diameter and an inner diameter substantially equal to those of the inner rings 23a and 23b. Arranged between the inner rings 23a and 23b of the angular ball bearings 20a and 20b.

Reference numeral 31 denotes an inner ring spacer, which is a cylindrical member having an outer diameter and an inner diameter substantially equal to the inner rings 23a and 23b, the inner peripheral surface of which is fitted to the outer peripheral surface of the fitting shaft 26, and between the inner rings of the inner ring 23b. It is arranged on the opposite side of the seat 30.
Reference numeral 32 denotes a lock nut, which is screwed into a screw portion 33 provided on the drive motor 14 side of the fitting shaft 26 of the screw shaft 11 and is engaged with the inner ring engaging portion 29 to form the inner ring 23a, the inner ring spacer 30, and the inner ring. 23b, the inner ring spacer 31 is tightened, and the axial movement of the inner rings 23a, 23b on the screw shaft 11 is fixed.

Reference numeral 34 denotes a coupling mounting portion, which is a small-diameter portion having a diameter equal to or less than the valley diameter of the screw portion 33 provided at the end of the screw shaft 11 on the drive motor 14 side. The power from the drive motor 14 is transmitted.
Reference numeral 36 denotes a piezoelectric actuator, which is a hollow actuator in which a single or a plurality of piezoelectric elements having a hollow portion 36a into which the inner ring spacer 31 can be inserted is laminated, and its outer peripheral surface is fitted to the inner diameter surface of the housing 27. It is arranged on the drive motor 14 side of 21b and expands and contracts in the axial direction according to the voltage applied from the outside.

The piezoelectric actuator 36 of the present embodiment is a laminated cylindrical actuator in which a plurality of annular piezoelectric elements are laminated.
Reference numeral 37 denotes an outer ring spacer, which is a cylindrical member having an outer diameter and an inner diameter substantially equal to those of the outer rings 21a and 21b, and an outer peripheral surface thereof is fitted to an inner diameter surface of the housing 27 so that the outer ring 21b and the piezoelectric actuator 36 are interposed. Placed in.

Reference numeral 38 denotes an outer ring locking portion, which is a step portion having a diameter substantially equal to the inner diameter of the outer rings 21a and 21b formed at a position facing the inner ring locking portion 29 on the inner peripheral surface of the housing 27, and the outer ring 21a. Lock one side of the.
Reference numeral 39 denotes a cover, which is a hollow disk member having an inner diameter into which the inner ring spacer 31 can be inserted and having an outer diameter substantially equal to that of the housing 27, and is formed on the end surface of the housing 27 on the drive motor 14 side. The hole 27a is fastened to the housing 27 with a bolt or the like, and presses the outer ring 21a, the outer ring 21b, the outer ring spacer 37, and the piezoelectric actuator 36 with the outer ring engaging portion 38.

As a result, the outer ring 21a is restrained from moving in the axial direction by the outer ring engaging portion 38, and the outer ring 21b on the non-restrained side is pressed via the outer ring spacer 37 and the non-energized piezoelectric actuator 36, and is disposed oppositely. A predetermined preload is applied to the ball bearings 20a and 20b, and a gap 40 is formed as an axial distance between the outer rings 21a and 21b.
Angular contact ball bearings 20a, 20b, fitting shaft 26, inner ring locking portion 29, inner ring spacer 30, inner ring spacer 31, lock nut 32 and housing 27, outer ring locking portion 38, outer ring spacer 37, piezoelectric actuator 36, As shown in FIG. 1, the cover 39 and the like are arranged coaxially with the screw shaft 11 to constitute the axial fine movement mechanism 41 with a rotation mechanism of the present embodiment.

The axial fine movement mechanism 41 with the rotation mechanism and the coarse movement mechanism 10 constitute the positioning device of this embodiment.
In FIG. 4, reference numeral 45 denotes a control device for the positioning device 1. The control unit 46 executes the positioning process of the positioning device 1 based on the output signal of the position sensor 17, a program executed by the control unit 46, various data used for the control unit 46. A storage unit 47 that stores the processing results by the control unit 46, a motor drive unit 48 that drives the drive motor 14, and an actuator drive unit 49 that drives the piezoelectric actuator 36 are provided.

  The storage unit 47 of the present embodiment recognizes the current position of the moving base 6 based on the output signal of the position sensor 17, and performs a motor drive program that performs coarse movement operation based on the deviation between the recognized current position and the target position. A positioning processing program for stopping the moving platform 6 at the target position by a fine movement operation program that performs fine movement operation by feedback control by PID control while taking in the information of the current position recognized by the sensor 17 is stored. Various functional means are formed as hardware of the positioning device 1 of the present embodiment by each step of the positioning processing program.

Further, the storage unit 47 stores a destination instruction table in which the target position for stopping the moving platform 6 and the stop time thereof are described.
The operation of the above configuration will be described.
When the positioning device 1 starts operation, the control unit 46 of the control device 45 activates a positioning processing program.

When the positioning processing program is activated, the control unit 46 sends an initial setting command to the actuator driving unit 49 to convert it into a voltage (referred to as an initial setting voltage Vo), which is supplied to the piezoelectric actuator 36 and held therein.
This initial set voltage Vo is a voltage that gives an extension of about half of the effective stroke of the piezoelectric actuator 36, and the position of the moving base 6 in the state where the initial set voltage Vo is applied to the piezoelectric actuator 36 is the original position.

Next, the control unit 46 confirms that the moving platform 6 has stopped at the original position, and reads the first target position and its stop time recorded in the movement destination instruction table of the storage unit 47.
The control unit 46 that has read the target position and the like calculates a difference in length (referred to as a deviation) between the target position and the current position (original position in this step), and sets the length corresponding to the calculated deviation to the ball screw device. The number of rotations of the screw shaft 11 required when the 13 nuts 12 are moved is calculated and sent to the motor drive unit 48 as a coarse motion command to be converted into a drive signal for the drive motor 14, which is sent to the drive motor 14. Supply.

Since the drive motor 14 of the present embodiment is a stepping motor, the drive signal is a pulse signal corresponding to the number of angular steps of the stepping motor necessary for rotating the calculated rotation speed of the screw shaft 11.
When the drive signal is supplied, the drive motor 14 rotates by the number of rotations corresponding to the drive signal, and the screw shaft 11 connected via the coupling 15 rotates and is fixed to the movable table 6. 12 is moved in the axial direction.

At this time, the control unit 46 receives a pulse-like output signal indicating the unevenness of the scale 18 output from the position sensor 17 as the moving table 6 moves, counts the number of the signals, and recognizes the position of the moving table 6. It waits for the stop of the movable table 6 (stop of rotation of the drive motor 14), and the position recognized when the movable table 6 stops is recognized as the current position.
In this way, the coarse movement operation of the movable stage 6 by the coarse movement mechanism 10 of the present embodiment in which the screw stage 11 is rotated to move the movable stage 6 fixed to the nut 12 in the axial direction with respect to the base 5. Is done.

In this case, the piezoelectric actuator 36 is only applied with the initial setting voltage Vo and is not subjected to feedback control by the position sensor 17.
In addition, the piezoelectric actuator 36 is in a state in which a compressive load due to the preload reaction force of the angular ball bearings 20a and 20b is applied.
The control unit 46 that has finished the coarse movement operation stops the motor drive program that performs the coarse movement operation, and switches the process to the fine movement operation program that performs the PID control while taking the position information of the position sensor 17. This fine movement operation program calculates a deviation between the current position recognized by the position sensor 17 and the first target position read out above, and sends a fine movement command to the actuator driver 49 to convert the voltage into a voltage so as to eliminate this deviation. This is a program for applying the control voltage to the piezoelectric actuator 36 for fine movement.

In the axial fine movement mechanism 41 with the rotation mechanism of the present embodiment, the displacement amount of the outer ring 21a and the inner ring 23a on the constrained side, which is half the displacement of the piezoelectric actuator 36, becomes the fine movement displacement amount of the moving base 6. At this time, a voltage obtained by adding the control voltage that gives a displacement twice as much as the deviation and the above-mentioned initial setting voltage Vo is applied to the piezoelectric actuator 36.
At this time, for example, when the piezoelectric actuator 36 is extended by 2X, the pressing force generated by the extension presses the outer ring 21b in addition to the preload before performing fine movement control, and the outer ring 21b is moved in the axial direction (left in FIG. 1). ), The gap 40 between the outer rings 21a and 21b is further narrowed by 2X to absorb the axial extension of the piezoelectric actuator 36.

  The displacement of the gap 40 is applied to the contact surface between the ball 25b and the outer ring raceway 22b and the inner ring raceway 24b and the contact surface between the ball 25a and the outer ring raceway 22a and the inner ring raceway 24a in addition to the preload before performing fine movement control. These are formed by further elastic deformation between them, the angular ball bearings 20a, 20b being displaced by X and the outer ring 21b being displaced by 2X in the axial direction.

Conversely, when the piezoelectric actuator 36 contracts by 2X, the pressing force decreases, the elastic displacement of each of the angular ball bearings 20a and 20b decreases by X, and the outer ring 21b is displaced by 2X along the axial direction so that the gap 40 expands. Thus, the contraction of the piezoelectric actuator 36 is absorbed.
As described above, the angular ball bearings 20a and 20b that are opposed to each other absorb the displacement 2X of the gap 40 so as to absorb each of the angular ball bearings 20a and 20b. The inner rings 23a and 23b fixed to the fitting shaft 26 of the shaft 11 in the axial direction are X-displaced together with the screw shaft 11 in the axial direction (left in FIG. 1). In this case, the movement of the screw shaft 11 is absorbed by the extension of the coupling 15 on the drive motor 14 side, and the movement of the opposite shaft end is absorbed by the play of the support bearing 16.

  As a result, the nut 12 screwed in the state where there is no play on the screw shaft 11 moves X in the axial direction, and the moving base 6 to which the nut 12 is fixed becomes the base 5 to which the housing 27 is fixed. On the other hand, X moves to the left in FIG. That is, the displacement amount of the outer ring 21 a and the inner ring 23 a on the restrained side, which is X displacement that is half of the 2X displacement (expansion / contraction amount) of the piezoelectric actuator 36, becomes the fine movement displacement amount of the moving platform 6.

In this way, the fine movement operation is performed, and the control unit 46 stops the moving platform 6 at the target position while performing feedback control so as to eliminate the deviation between the current position recognized by the position sensor 17 and the target position.
When the moving platform 6 is stopped at the target position during the stop time read out above, the control unit 46 reads the target position and stop time recorded in the movement destination instruction table again, and the next target position and the like are recorded. If it is, the control voltage held by the actuator drive unit 49 for the fine movement operation is released, and the movement amount of the moving table 6 resulting from the result is counted by the output signal of the position sensor 17 in the same manner as described above. Then, the new current position is recognized, and the coarse movement operation according to the deviation between the current position and the next target position and the fine movement operation by feedback control are executed in the same manner as described above.

In this way, the positioning process can be sequentially performed according to the positioning process program.
In this embodiment, the clearance 40 between the outer rings 21a and 21b of the angular ball bearings 20a and 20b is changed by the expansion and contraction of the piezoelectric actuator 36 to perform a fine movement operation. As a result, the preload is changed. The elongation associated with the fine movement of the piezoelectric actuator 36 is about 10 μm at maximum, usually about several μm, and the change in the preload caused thereby is small. Therefore, the outer ring raceways 22a and 22b, the inner ring raceways 24a and 24b, balls Indentation or the like does not occur in 25a and 25b.

As described above, the axial fine movement mechanism 41 with the rotation mechanism of the present embodiment causes the preload reaction force applied to the angular ball bearings 20a and 20b of the front combination to act on the piezoelectric actuator 36 disposed on the outer rings 21a and 21b side. Since the coarse motion operation and the fine motion operation are performed while always applying a compressive load, there is no occurrence of breakage due to a tensile load, and there is no need to use a spring to avoid it.
Further, the bearing unit can be assembled in the same manner as the method of assembling the bearing unit only by using the housing 27 and the screw shaft 11 that are longer than the piezoelectric actuator 36, and can be easily assembled without paying special attention to the assembly of the piezoelectric actuator 36. The axial fine movement mechanism 41 with the rotation mechanism can be assembled.

Furthermore, since the piezoelectric actuator 36 is automatically arranged coaxially when incorporated in the housing 27 with the inner peripheral surface of the housing 27 as a guide, a radial load, moment force, etc. act on the piezoelectric actuator 36 to cause early breakage, etc. Will not occur.
Further, the axial fine movement mechanism 41 with the rotation mechanism of the present embodiment does not have a spring with low rigidity, and the angular ball bearings 20a and 20b function as spring members with extremely high rigidity, so that the piezoelectric actuator 36 is always subjected to a compressive load. Since the coarse and fine movements are performed while applying the load, the combination of the piezoelectric actuator 36 having a very high rigidity with respect to the load in the compression direction and the highly rigid spring member makes the rigidity of the entire positioning device static. nor it is possible to maintain the bearing unit and substantially the same stiffness without incorporated piezoelectric actuator 36 to dynamically, fast, can be determined promptly by using an stable micromotion operation of the high response.

Furthermore, since the piezoelectric actuator 36 can be arranged coaxially with the screw shaft 11, the displacement of the piezoelectric actuator 36 can be a pure axial displacement, and a highly accurate fine movement operation can be performed.
As described above, in the present embodiment, the outer peripheral surfaces of the outer rings of the two angular ball bearings arranged opposite to each other are fitted to the inner peripheral surface of the housing of the axial fine movement mechanism with the rotation mechanism of the positioning device, By pressing the piezoelectric actuator with the preload reaction force applied to the opposed angular ball bearings, the opposed angular ball bearings function as extremely rigid spring members, and the piezoelectric actuators are always subjected to compressive loads. Coarse and fine movements can be performed while applying pressure, and it is possible to prevent the piezoelectric actuator from being damaged by a tensile load and to combine a high rigidity spring member with high rigidity in the compression direction of the piezoelectric actuator. Accordingly, it is possible to maintain high rigidity of the entire positioning device, high-speed, it is possible to perform stable micromotion operation of the high-response Kill.

  In addition, by applying the preload in a state where the piezoelectric actuator is not energized in advance, the effective stroke of the piezoelectric actuator can be utilized to the maximum, so that the piezoelectric actuator can be reduced in size and cost. Further, it is only necessary to energize the piezoelectric actuator only when performing the positioning operation, and the energization time is shortened, so that the durability of the piezoelectric actuator can be improved.

Furthermore, since the piezoelectric actuator is a laminated type, the piezoelectric actuator can be easily manufactured.
Further, by performing the fine movement operation by the piezoelectric actuator of the axial fine movement mechanism with the rotation mechanism of the positioning device when the rotation of the coarse movement operation is stopped, the movement of the coarse movement operation and the fine movement operation overlap, Since the controls do not interfere with each other so that the movement of the coarse motion is corrected by fine motion, the control device becomes simple, and even if the preload amount of the angular ball bearing changes due to the displacement of the piezoelectric actuator during the fine motion operation. Since the angular ball bearing is not rotating, there is no influence such as an increase in torque accompanying a change in preload.

Furthermore, the lead error of the screw shaft can be improved by feeding back the deviation between the current position and the target position recognized by the output signal indicating the relative movement between the base and the moving base from the position sensor. Even when there is hysteresis or the like of the piezoelectric actuator, highly accurate fine positioning can be performed.
In addition to the above, in this embodiment, the piezoelectric actuator is hollow and fitted to the inner peripheral surface of the housing, and the screw shaft is inserted and arranged coaxially with the screw shaft, so that it is longer by the length of the piezoelectric actuator. By simply using the housing and the screw shaft, the bearing unit can be assembled by the same method as that for assembling, and the axial fine movement mechanism with a rotating mechanism using the piezoelectric actuator can be easily assembled.

  Further, the inner peripheral surface of each inner ring of the two angular ball bearings arranged opposite to each other is fitted to the outer peripheral surface of the fitting portion of the screw shaft, and the inner ring engaging portion and the lock nut are moved in the axial direction of each inner ring. And fixed to the screw shaft, the axial movement of one of the angular rings of the two angular ball bearings is constrained to the housing by the outer ring locking portion, and the other is moved in the axial direction by the piezoelectric actuator. Thus, half of the displacement of the piezoelectric actuator due to the application of the control voltage can be made the displacement of the screw shaft, and the displacement error of the piezoelectric actuator can be halved to realize a highly accurate fine movement operation.

  Furthermore, by arranging the piezoelectric actuator so as to press the outer ring on the non-rotating side of the angular ball bearing, wiring to the piezoelectric actuator can be easily performed.

FIG. 5 is a cross-sectional view showing an axial fine movement mechanism with a rotation mechanism according to the second embodiment, and FIG. 6 is an explanatory view seen from the side showing the positioning device according to the second embodiment.
In addition, the same part as the said Example 1 attaches | subjects the same code | symbol, and abbreviate | omits the description.
5 and 6, reference numeral 50 denotes a piezoelectric actuator, which is a solid actuator in which a single or a plurality of piezoelectric elements are stacked on a pillar, and expands and contracts in the axial direction according to an applied voltage. The piezoelectric actuator 50 of this embodiment is a solid actuator in which piezoelectric elements are stacked in a prismatic shape (for example, a resin exterior actuator, model number AE0505D08, manufactured by NEC Tokin Corporation).

Reference numeral 51 denotes a piston, which is a cylindrical member that fits to the inner peripheral surface of the housing 27, and an accommodation hole 52 that accommodates the piezoelectric actuator 50 along the axis of the piston 51 is formed on the end surface on the cover 39 side. A clearance hole 53 for avoiding interference with the lock nut 32 is formed on the opposite end surface.
The cover 39 is formed with a concave hole 54 having an inner diameter equivalent to that of the storage hole 52 along the axis.

The inner diameters of the storage hole 52 and the recessed hole 54 of the present embodiment are formed to have a diameter in which four corners of the prismatic piezoelectric actuator 50 are inscribed. As a result, the piezoelectric actuator 50 is disposed substantially at the axis of the screw shaft 11.
As shown in FIG. 6, the fine movement device 41 of this embodiment is disposed at the end opposite to the end of the screw shaft 11 to which the drive motor 14 is connected via the coupling 15, and the housing 27 is a bolt. It is being fixed to the base 5 by etc.

The support bearing 16 of the present embodiment is disposed on the inner side of the coupling 15 at the end of the screw shaft 11 on the drive motor 14 side, and is installed on the base 5 to rotatably support the screw shaft 11 and the screw shaft. 11 is movably supported by play in the axial direction.
As shown in FIG. 5, the axial fine movement mechanism 41 with the rotation mechanism of the present embodiment uses the inner rings 23 a, 23 b of the angular ball bearings 20 a, 20 b that face each other through the inner ring spacer 30 in front combination as the fitting shaft 26. The inner ring 23 a, the inner ring spacer 30, and the inner ring 23 b are tightened with the lock nut 32 between the inner ring locking portion 29 and the inner ring 23 a, 23 b are fixed to the screw shaft 11. The axial movement of the outer ring 21 a fitted to the inner peripheral surface is restrained by the outer ring locking portion 38, and the lock nut 32 is enclosed in the escape hole 53 of the piston 51 fitted to the inner peripheral surface of the housing 27. The end face on the side is brought into contact with the outer ring 21b on the unconstrained side, the non-energized piezoelectric actuator 50 is inserted into the housing hole 52, the concave hole 54 of the cover 39 is fitted into the piezoelectric actuator 50, and the -39 is fastened to the housing 27 with bolts or the like, and the outer ring 21a, the outer ring 21b, the piston 51 and the piezoelectric actuator 50 are tightened with the outer ring engaging portion 38, and the above-mentioned components are arranged coaxially with the screw shaft 11. .

As a result, the piezoelectric actuator 50 is sandwiched between the bottom surfaces of the storage hole 52 and the recessed hole 54, the outer ring 21b is pressed via the piston 51 and the piezoelectric actuator 50, and a predetermined preload is applied to the angular ball bearings 20a, 20b disposed opposite to each other. And a gap 40 between the outer rings 21a and 21b is formed.
The coarse movement mechanism 10 of this embodiment is disposed on the opposite side of the piezoelectric actuator 50 of the screw shaft 11 as shown in FIG.

The operation of the above configuration will be described.
The positioning device 1 of the present embodiment is equipped with the control device 45 shown in FIG.
Since the coarse movement operation and the fine movement operation of this embodiment are the same as those of the first embodiment, description thereof will be omitted. In this case, when the piezoelectric actuator 50 is extended by a displacement 2X that is twice the deviation X, the screw shaft 11 is X-displaced to the left in FIG. 5 as in the first embodiment, and the movement of the screw shaft 11 at this time is the support bearing 16. Are absorbed by the axial play and the contraction of the coupling 15.

  As described above, the axial fine movement mechanism 41 with the rotation mechanism of the present embodiment has a reaction force of the preload applied to the front combination angular ball bearings 20a, 20b via the piston 51 disposed on the outer ring 21a, 21b side. Since the coarse motion operation and the fine motion operation are performed while applying a compressive load at all times on the actual piezoelectric actuator 50, there is no occurrence of breakage due to a tensile load, and there is no need to use a spring to avoid it.

Also, the bearing unit can be assembled by the same method as the method of assembling the bearing unit only by using the housing 27 that is longer than the piezoelectric actuator 50, and the shaft with the rotation mechanism can be easily assembled without paying special consideration to the assembly of the piezoelectric actuator 36. The direction fine movement mechanism 41 can be assembled.
Further, if the piezoelectric actuator 50 is incorporated into the piston 51 with the receiving hole 52 of the piston 51 and the concave hole 54 of the cover 39 as a guide, the piezoelectric actuator 50 is automatically arranged coaxially. Will not cause premature breakage.

Further, the axial fine movement mechanism 41 with the rotation mechanism of the present embodiment does not have a spring with low rigidity as in the first embodiment, so that the piezoelectric actuator 50 having a very high rigidity with respect to a load in the compression direction and a high rigidity are applied. By combining with a rigid spring member, the rigidity of the entire positioning device can be maintained substantially the same as that of a bearing unit that does not incorporate the piezoelectric actuator 36 both statically and dynamically, and stable at high speed and high response. it is as possible out to perform a fine movement behavior.

Furthermore, since the piezoelectric actuator 50 can be arranged coaxially with the screw shaft 11, the displacement of the piezoelectric actuator 50 can be made a pure axial displacement, and a highly accurate fine movement operation can be performed.
As described above, in the present embodiment, the same effect as in the first embodiment can be obtained also by making the piezoelectric actuator solid and disposing it on the substantially shaft core of the screw shaft.

  In addition to the above, in this embodiment, the piezoelectric actuator is solidly fitted into the piston housing hole and the cover recessed hole, and is sandwiched between the respective bottom surfaces and arranged coaxially with the screw shaft. Therefore, it is possible to assemble the bearing unit by the same method as the method of assembling the bearing unit only by using a housing that is as long as the piezoelectric actuator, and it is possible to easily assemble the axial fine movement mechanism with a rotating mechanism using the piezoelectric actuator. In addition, the cost of the positioning device can be reduced by reducing the price of a piezoelectric actuator that is generally more expensive as the volume increases.

  Further, the inner peripheral surface of each inner ring of the two angular ball bearings arranged opposite to each other is fitted to the outer peripheral surface of the fitting portion of the screw shaft, and the inner ring engaging portion and the lock nut are moved in the axial direction of each inner ring. Is fixed to the screw shaft, and the axial movement of one of the angular rings of the two angular ball bearings is constrained to the housing by the outer ring locking portion, and the other is moved axially via the piston by the piezoelectric actuator. By doing so, half of the displacement of the piezoelectric actuator due to the application of the control voltage can be made the displacement of the screw shaft, and the error of the displacement of the piezoelectric actuator can be halved to realize a highly accurate fine movement operation. .

  Furthermore, by arranging the piezoelectric actuator so as to press the outer ring on the non-rotating side of the angular ball bearing, wiring to the piezoelectric actuator can be easily performed.

FIG. 7 is a cross-sectional view showing an axial fine movement mechanism with a rotation mechanism according to the third embodiment.
In addition, the same part as the said Example 1 attaches | subjects the same code | symbol, and abbreviate | omits the description.
In the coarse movement mechanism 10 and the axial fine movement mechanism 41 with the rotation mechanism of the present embodiment, a housing 27 is fixed to the base 5 of the positioning device 1 and the movable base 6 is mounted in the same manner as in the first embodiment (for example, FIG. 3). The nut 12 is fixed.

The angular ball bearings 20a and 20b of the axial fine movement mechanism 41 with the rotation mechanism of the present embodiment are arranged to face each other through the inner ring spacer 30 in the rear combination, and the respective inner rings 23a and 23b are fitted to the fitting shaft 26. Together with the inner ring spacer 30, the lock nut 32 is tightened to the inner ring locking portion 29 to fix the movement in the axial direction.
The housing 27 of the present embodiment is provided with a screw hole 27b for screwing a presser plug 57 having a male screw formed on the outer peripheral surface thereof at the end on the nut 12 side, and is provided on the inner side of the screw hole 27b. One outer ring 21a fitted to the inner peripheral surface of the housing 27 is fastened by a presser plug 57 to an outer ring locking portion 38 provided on the inner peripheral surface, and its axial movement is restricted.

  A cylindrical piezoelectric actuator 36 having an outer peripheral surface similar to that of the first embodiment fitted to the inner diameter surface of the housing 27 is in contact with the surface opposite to the contact surface with which the outer ring 21 a contacts the outer ring locking portion 38. The outer ring 21b on the side that is not restrained is arranged outside the actuator 36, and when the inner rings 23a and 23b are tightened by the lock nut 32, the outer ring 21b is pressed to the outside via the piezoelectric actuator 36 and is opposed to the rear combination. A predetermined preload is applied to the angular ball bearings 20a and 20b, and nothing prevents the outer ring 21b from moving in the axial direction.

As described above, the axial fine movement mechanism 41 with the rotation mechanism of the present embodiment is configured by arranging the above-described components on the same axis as the screw shaft 11 as shown in FIG.
The operation of the above configuration will be described.
The positioning device 1 of the present embodiment is equipped with the control device 45 shown in FIG.

Since the coarse motion operation of this embodiment is the same as that of the first embodiment, the description thereof is omitted.
The control unit 46 that has finished the coarse movement operation calculates the expansion / contraction amount of the piezoelectric actuator 36 from the deviation between the current position and the target position in the same manner as in the first embodiment, and the voltage converted by the actuator drive unit 49 using this as a fine movement command. Is supplied to the piezoelectric actuator 36 and held.
Also in the axial fine movement mechanism 41 with the rotation mechanism of the present embodiment, as in the first embodiment, the displacement amounts of the outer ring 21a and the inner ring 23a on the constrained side that are half the displacement of the piezoelectric actuator 36 are The amount of fine movement displacement.

That is, when the piezoelectric actuator 36 of the axial fine movement mechanism 41 with the rotation mechanism of the present embodiment extends by a displacement 2X that is twice the deviation X by the applied voltage, the piezoelectric actuator 36 that is in contact with the outer ring locking portion 38. Moves the outer ring 21b in the axial direction (right in FIG. 7), and acts to enlarge the space between the outer rings 21a and 21b.
The displacement of the outer ring 21b is applied to the contact surface between the ball 25b and the outer ring raceway 22b and the inner ring raceway 24b and the contact surface between the ball 25a and the outer ring raceway 22a and the inner ring raceway 24a in addition to the preloading load. The elastic ball bearings 20a and 20b are displaced by X each time, the outer ring 21b is displaced by 2X in the axial direction, and the outer rings 21a and 21b are expanded by 2X to extend the piezoelectric actuator 36 in the axial direction. Absorb.

As described above, the angular ball bearings 20a and 20b arranged opposite to each other absorb the enlarged portion 2X of the distance between the outer rings 21a and 21b, and the force that presses the angular ball bearings 20a and 20b against each other is absorbed. When balanced, the inner rings 23a and 23b restrained in the axial movement by the fitting shaft 26 of the screw shaft 11 are X-displaced together with the screw shaft 11 in the axial direction (right in FIG. 7). The movement of the screw shaft 11 in this case is absorbed by the contraction of the coupling 15 on the drive motor 14 side, and the movement of the shaft end on the opposite side is absorbed by the play of the support bearing 16.

As a result, the nut 12 screwed in the state where there is no play on the screw shaft 11 moves X in the axial direction, and the moving base 6 to which the nut 12 is fixed becomes the base 5 to which the housing 27 is fixed. On the other hand, X moves to the right in FIG.
In this way, the fine movement operation of the moving platform 6 due to the elongation of the piezoelectric actuator 36 of this embodiment is performed, Oite this fine movement operation, the feedback control by the control unit 46 based on a deviation in the same manner as in Example 1 To stop the movable table 6 at the target position.

Since the subsequent operation is the same as that of the first embodiment, the description thereof is omitted.
As described above, the axial fine movement mechanism 41 with the rotation mechanism of the present embodiment acts on the piezoelectric actuator 36 in which the reaction force of the preload applied to the rear combination angular ball bearings 20a and 20b is arranged inside the outer rings 21a and 21b. Since the coarse motion and the fine motion are performed while constantly applying a compressive load, there is no occurrence of breakage due to a tensile load, and there is no need to use a spring to avoid it.

Further, the bearing unit can be assembled in the same manner as the method of assembling the bearing unit only by using the housing 27 and the screw shaft 11 that are longer than the piezoelectric actuator 36, and can be easily assembled without paying special attention to the assembly of the piezoelectric actuator 36. The axial fine movement mechanism 41 with the rotation mechanism can be assembled.
Furthermore, since the piezoelectric actuator 36 is automatically arranged coaxially when incorporated in the housing 27 with the inner peripheral surface of the housing 27 as a guide, a radial load, moment force, etc. act on the piezoelectric actuator 36 to cause early breakage, etc. Will not occur.

Further, the axial fine movement mechanism 41 with the rotation mechanism of the present embodiment does not have a spring having a low rigidity as in the first embodiment, so that the piezoelectric actuator 36 having a very high rigidity with respect to a load in the compression direction and a high rigidity. By combining with a rigid spring member, the rigidity of the entire positioning device can be maintained substantially the same as that of a bearing unit that does not incorporate the piezoelectric actuator 36 both statically and dynamically, and stable at high speed and high response. it is as possible out to perform a fine movement behavior.

Furthermore, since the piezoelectric actuator 36 can be arranged coaxially with the screw shaft 11, the displacement of the piezoelectric actuator 36 can be a pure axial displacement, and a highly accurate fine movement operation can be performed.
As described above, in the present embodiment, even when the angular ball bearing is a back combination, the same effect as in the first embodiment can be obtained.

  In addition to the above, in this embodiment, a hollow piezoelectric actuator is arranged between the outer rings of the angular ball bearings that are combined on the back surface, and is fitted to the inner peripheral surface of the housing, and the screw shaft is inserted into the screw shaft. Because it is arranged coaxially, it can be assembled in the same way as the method of assembling the bearing unit only by using a housing and a screw shaft that are as long as the piezoelectric actuator, and the axial direction with a rotating mechanism using a piezoelectric actuator. The fine movement mechanism can be easily assembled.

  Further, the inner peripheral surface of each inner ring of the two angular ball bearings arranged opposite to each other is fitted to the outer peripheral surface of the fitting portion of the screw shaft, and the inner ring engaging portion and the lock nut are moved in the axial direction of each inner ring. And fixed to the screw shaft, the axial movement of one of the angular rings of the two angular ball bearings is constrained to the housing by the outer ring locking portion, and the other is moved in the axial direction by the piezoelectric actuator. Thus, half of the displacement of the piezoelectric actuator due to the application of the control voltage can be made the displacement of the screw shaft, and the displacement error of the piezoelectric actuator can be halved to realize a highly accurate fine movement operation.

  Furthermore, by arranging the piezoelectric actuator so as to press the outer ring on the non-rotating side of the angular ball bearing, wiring to the piezoelectric actuator can be easily performed.

FIG. 8 is a cross-sectional view showing an axial fine movement mechanism with a rotation mechanism according to the fourth embodiment, and FIG. 9 is an explanatory view seen from the side showing the positioning device according to the fourth embodiment.
In addition, the same part as the said Example 1 attaches | subjects the same code | symbol, and abbreviate | omits the description.
8 and 9, reference numeral 61 denotes a nut of the ball screw device 13, and a nut raceway groove (not shown) facing the shaft raceway groove 11a is formed on the inner peripheral surface in the same manner as in the first embodiment. The screw shaft 11 is screwed through a non-playing ball without play.

The outer peripheral surface of the nut 61 is fitted with the inner peripheral surfaces of the inner rings 23a and 23b of the angular ball bearings 20a and 20b arranged to face each other as a front combination, and the lock nut 32 is screwed to one end of the nut 61. A screw portion 62 is formed.
Reference numeral 63 denotes an inner ring locking portion, which is a large-diameter portion having a diameter substantially equal to the outer diameter of the inner rings 23a and 23b formed at the end of the nut 61 on the opposite side of the threaded portion 62. Lock the sides.

Reference numeral 64 denotes an inner ring spacer, which is a cylindrical member having an outer diameter and an inner diameter substantially equal to those of the inner rings 23a and 23b, and an angular ball whose inner peripheral surface is fitted to the outer peripheral surface of the nut 61 and arranged oppositely. It arrange | positions between the inner ring | wheels 23a and 23b of the bearings 20a and 20b.
65 is the inner ring spacer, a cylindrical member having an inner ring 23a, 23b and outer and inner diameters substantially equal, the inner ring spacer 30 of the inner ring 23b fitted inner peripheral surface thereof on an outer peripheral surface of the nut 61 It is arranged on the opposite side.

Reference numeral 67 denotes a drive motor, which is a hollow motor capable of forward and reverse rotation, such as a stepping motor having a hollow hole into which the screw shaft 11 is inserted (for example, Asahi Engineering Co., Ltd., hollow stepping motor, HSM series). The nut 68 is rotationally driven by being coupled to the screw portion 62 side of the nut 61 by the ring 68.
The angular ball bearings 20a, 20b of the present embodiment are arranged to face each other via an inner ring spacer 64 in front combination, and an inner ring 23a, an inner ring spacer 64, an inner ring 23b, and an inner ring spacer 65 are disposed between the inner ring locking portion 63 and the inner ring spacer. The inner rings 23a and 23b are fastened by the lock nut 32, and the axial movement thereof is fixed to the nut 61.

  Similarly to the first embodiment, the outer ring 21a is fitted to the inner peripheral surface of the housing 27 and its axial movement is restrained by the outer ring engaging portion 38, and the outer ring 21b on the unconstrained side is the outer ring spacer 37 and the piezoelectric actuator. A predetermined preload is applied to the angular ball bearings 20a and 20b, which are pressed by fastening the cover 39 to the housing 27 through 36, and are arranged opposite to each other, and a gap 40 is formed between the outer rings 21a and 21b.

  The screw shaft 11 of this embodiment is fixed to fixed portions 69 arranged on both sides of the base 5, the housing 27 and the drive motor 67 are fixed to the moving base 6, and the coarse motion mechanism 10 of this embodiment is It is formed by screwing the axial movement and rotation into the fixed screw shaft 11 and rotating the nut 61 rotatably supported by the angular ball bearings 20a and 20b through the coupling 68 by the drive motor 67. The

The axial fine movement mechanism 41 with the rotation mechanism of the present embodiment includes angular ball bearings 20a and 20b, a nut 61, an inner ring locking part 63, an inner ring spacer 64, an inner ring spacer 65, a lock nut 32 and a housing 27, and an outer ring unit. The stopper 38, the outer ring spacer 37, the piezoelectric actuator 36, the cover 39 and the like are arranged on the same axis of the nut 61 as shown in FIG.
The operation of the above configuration will be described.

The positioning device 1 of the present embodiment is equipped with the control device 45 shown in FIG. In this case, the motor drive unit 48 has a function of sending a drive signal for driving the drive motor 67.
In the coarse movement operation of the present embodiment, when the positioning processing program is started in the same manner as in the first embodiment, the control unit 46 applies the initial setting voltage Vo from the actuator driving unit 49 to the piezoelectric actuator 36. This initial set voltage Vo is a voltage that gives an extension of about half of the effective stroke of the piezoelectric actuator 36, and the position of the moving base 6 in the state where the initial set voltage Vo is applied to the piezoelectric actuator 36 is the original position.

Next, the control unit 46 confirms the stop of the original position of the moving base 6 and reads the first target position and the like.
The control unit 46 that has read the target position and the like calculates the deviation between the target position and the current position in the same manner as in the first embodiment, and moves the length corresponding to the deviation calculated by the nut 12 of the ball screw device 13. The number of rotations of the nut 61 required for the operation is calculated, and this is sent to the motor drive unit 48 as a coarse motion command to be converted into a drive signal for the drive motor 67, which is supplied to the drive motor 67.

Since the drive motor 67 of the present embodiment is a stepping motor, the drive signal is a pulse signal corresponding to the number of angular steps of the stepping motor necessary for rotating the calculated rotation speed of the nut 61.
When the drive signal is supplied, the drive motor 67 rotates by the number of rotations corresponding to the drive signal, and the nut 61 connected through the coupling 68 is fixed to the base 5 by the fixing portion 69. The moving table 6 that rotates on the screw shaft 11 and is fixed to the housing 27 that rotatably supports the nut 61 by the angular ball bearings 20a and 20b is moved in the axial direction.

At this time, the control unit 46 receives an output signal output from the position sensor 17 as the moving table 6 moves in the same manner as in the first embodiment, and stops the moving table 6 (stops the rotation of the drive motor 67). 6 is recognized.
In this way, the coarse movement mechanism of the present embodiment in which the nut 61 is rotated to move the moving base 6 fixed to the housing 27 rotatably supporting the nut 61 in the axial direction with respect to the base 5. The coarse movement operation of the movable table 6 by 10 is performed.

In this case, the piezoelectric actuator 36 is only applied with the initial setting voltage Vo and is not subjected to feedback control by the position sensor 17.
In addition, the piezoelectric actuator 36 is in a state in which a compressive load due to the preload reaction force of the angular ball bearings 20a and 20b is applied.
After the coarse movement operation, the control unit 46 calculates the deviation between the current position recognized by the position sensor 17 and the first target position read out as described above, and eliminates this deviation, as in the first embodiment. As described above, the actuator driving unit 49 applies a control voltage to the piezoelectric actuator 36 to perform a fine movement operation.

Also in the axial fine movement mechanism 41 with the rotation mechanism of the present embodiment, as in the first embodiment, the displacement amounts of the outer ring 21a and the inner ring 23a on the constrained side that are half the displacement of the piezoelectric actuator 36 are The amount of fine movement displacement.
That is, when the piezoelectric actuator 36 is extended by 2X in the same manner as in the first embodiment, the pressing force generated by this extension presses the outer ring 21b in addition to the preload before performing the fine movement operation, and the outer ring 21b is axially moved. (In this description, it moves to the left in FIG. 8) and acts so that the gap 40 between the outer rings 21a and 21b becomes narrower, and the displacement of the gap 40 is the same as that of the first embodiment when the angular ball bearings 20a and 20b Each is displaced by X, and the gap 40 is narrowed by 2X to absorb the elongation of the piezoelectric actuator 36 in the axial direction.

As described above, the angular ball bearings 20a and 20b disposed so as to oppose the displacement 2X of the gap 40 are absorbed by X, so that when the force of the angular ball bearings 20a and 20b pressing each other is balanced, the nut The inner rings 23 a and 23 b restricted in the axial movement by 61 are X-displaced in the axial direction together with the nut 61. The movement of the nut 61 in this case is absorbed by the extension of the coupling 68 on the drive motor 67 side.

As a result, the nut 61 moves X in the axial direction, and the moving base 6 on which the housing 27 that supports the angular ball bearings 20a and 20b that are restrained from moving in the axial direction by the nut 61 is fixed, and the screw shaft 11 is fixed. The X moves in the right direction in FIG.
Oite this fine movement operation, control unit 46 performs feedback control based on the deviation in the same manner as in Example 1, to stop the moving platform 6 to the target position.

Since the subsequent operation is the same as that of the first embodiment, the description thereof is omitted.
As described above, the axial fine movement mechanism 41 with the rotation mechanism of the present embodiment causes the preload reaction force applied to the angular ball bearings 20a and 20b of the front combination to act on the piezoelectric actuator 36 disposed on the outer rings 21a and 21b side. Since the coarse motion operation and the fine motion operation are performed while always applying a compressive load, there is no occurrence of breakage due to a tensile load, and there is no need to use a spring to avoid it.

Further, the bearing unit can be assembled in the same manner as the method of assembling the bearing unit only by using the housing 27 and the screw shaft 11 that are longer than the piezoelectric actuator 36, and can be easily assembled without paying special attention to the assembly of the piezoelectric actuator 36. The axial fine movement mechanism 41 with the rotation mechanism can be assembled.
Furthermore, since the piezoelectric actuator 36 is automatically arranged coaxially when incorporated in the housing 27 with the inner peripheral surface of the housing 27 as a guide, a radial load, moment force, etc. act on the piezoelectric actuator 36 to cause early breakage, etc. Will not occur.

  Further, the axial fine movement mechanism 41 with the rotation mechanism of the present embodiment does not have a spring having a low rigidity as in the first embodiment, so that the piezoelectric actuator 36 having a very high rigidity with respect to a load in the compression direction and a high rigidity. By combining with a rigid spring member, the rigidity of the entire positioning device can be maintained substantially the same as that of a bearing unit that does not incorporate the piezoelectric actuator 36 both statically and dynamically, and stable at high speed and high response. A fine movement can be performed.

Furthermore, since the piezoelectric actuator 36 can be arranged coaxially with the nut 61, the displacement of the piezoelectric actuator 36 can be made a pure axial displacement, and a highly accurate fine movement operation can be performed.
As described above, in this embodiment, the housing is provided with an angular ball bearing disposed opposite to the inner ring on the outer peripheral surface of the nut so as to rotatably support the nut, and the outer ring is axially supported by the piezoelectric actuator. Also by pressing, the same effect as in Example 1 can be obtained.

  In addition to the above, in this embodiment, the piezoelectric actuator is made hollow and fitted to the inner peripheral surface of the housing, and the nut is inserted and arranged coaxially with the nut. By simply using the screw shaft, the bearing unit can be assembled in the same manner as the method of assembling, and an axial fine movement mechanism with a rotating mechanism using a piezoelectric actuator can be easily assembled.

  In addition, the inner peripheral surface of each inner ring of the two angular ball bearings arranged opposite to each other is fitted to the outer peripheral surface of the nut, and the axial movement of each inner ring is sandwiched between the inner ring engaging portion and the lock nut, and the nut The axial movement of one of the angular rings of the two angular ball bearings is restrained by a housing fixed to the moving table by the outer ring locking portion, and the other is moved in the axial direction by a piezoelectric actuator. Therefore, half of the displacement of the piezoelectric actuator due to the application of the control voltage can be made the displacement of the moving table, and the displacement error of the piezoelectric actuator can be halved to realize a highly accurate fine movement operation.

  Furthermore, by arranging the piezoelectric actuator so as to press the outer ring on the non-rotating side of the angular ball bearing, wiring to the piezoelectric actuator can be easily performed.

FIG. 10 is a cross-sectional view illustrating an axial fine movement mechanism with a rotation mechanism according to the fifth embodiment.
Note that the axial fine movement mechanism 41 with the rotation mechanism of the present embodiment is installed with the housing 27 fixed to the base 5 at the same site as in FIG. 3 of the first embodiment. The same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.
The inner peripheral surfaces of the inner rings 23a and 23b of the angular ball bearings 20a and 20b arranged opposite to each other as a rear combination are fitted to the fitting shaft 26 of the screw shaft 11 of this embodiment, and are adjacent to the inner ring 23b. A piezoelectric actuator 36 in which the hollow portion 36a is fitted to the fitting shaft 26 is disposed.

In FIG. 10, reference numeral 71 denotes an outer ring spacer, which is a cylindrical member having an outer diameter and an inner diameter substantially equal to those of the outer rings 21a and 21b, and the outer peripheral surface thereof is fitted to the inner peripheral surface of the housing 27 so as to face each other. The angular ball bearings 20a and 20b are arranged between the outer rings 21a and 21b.
Reference numeral 72 denotes an outer ring spacer, which is a cylindrical member having an outer diameter and an inner diameter substantially equal to those of the outer rings 21a and 21b. Be placed.

Reference numeral 73 denotes a slip ring, which is a cylindrical member whose inner peripheral surface is fitted to a fitting shaft 26 made of an insulating material such as a highly rigid ceramic material or composite resin material. Two electrode rings 74 made of a conductive metal material such as the like are provided, and each electrode ring 74 is electrically connected to the adjacent piezoelectric actuator 36.
Reference numeral 75 denotes a fixed-side electrode, which is configured by providing two brushes 76 incorporating a spring element formed of a conductive material such as carbon on a thick flat plate formed of an insulating material such as a resin material. It attaches to the inner peripheral part of the cover 39 by etc.

Each of the brushes 76 is electrically connected to the actuator driving unit 49 of the control device 45 and presses the electrode ring 74 that rotates together with the screw shaft 11 to electrically connect the stationary system and the rotating system. As a result, the control voltage from the actuator driver 49 is transmitted to the piezoelectric actuator 36 via the slip ring 73.
The angular ball bearings 20a, 20b of the present embodiment are arranged to face each other via the outer ring spacer 71 in the rear combination, and the outer ring 21a, the outer ring spacer 71, the outer ring 21b, and the outer ring spacer 72 are between the outer ring locking portion 38. The cover 39 is fastened by fastening to the housing 27, and the outer rings 21 a and 21 b are fixed to the housing 27 in the axial direction.

  The inner ring 23a is fitted to the outer peripheral surface of the fitting shaft 26, and its axial movement is restrained by the inner ring engaging portion 29, and the inner ring 23b on the unconstrained side slips by a lock nut 32 which is tightened with a specified torque. A predetermined preload is applied to the angular ball bearings 20a, 20b, which are pressed through the ring 73 and the piezoelectric actuator 36, and are arranged opposite to each other, and a gap 40 is formed as an axial distance between the inner rings 23a, 23b. .

  As in the first embodiment, the screw shaft 11 of this embodiment is supported by the support bearing 16 at the other end and is rotationally driven by the drive motor 14. The housing 27 is fixed to the base 5, and the nut 12 of the ball screw device 13 is The coarse movement mechanism 10 of this embodiment is formed by rotating a screw shaft 11 fixed to the movable table 6 and screwed into the nut 12 through a coupling 15 by a drive motor 14.

  Further, the axial fine movement mechanism 41 with a rotation mechanism of this embodiment includes angular ball bearings 20a and 20b, a fitting shaft 26, an inner ring locking portion 29, a piezoelectric actuator 36, a slip ring 73, a lock nut 32 and a housing 27, and an outer ring. The engaging portion 38, the outer ring spacer 71, the outer ring spacer 72, the cover 39 and the like are arranged on the same axis of the screw shaft 11 as shown in FIG.

The operation of the above configuration will be described.
The positioning device 1 of this embodiment, the control device 45 shown in the same FIG. 4 as in Example 1 is equipped. In this case, the actuator driving unit 49 has a function of holding a voltage applied to the piezoelectric actuator 36 via the brush 76 of the fixed side electrode 75 and the electrode ring 74 of the slip ring 73.

Since the coarse movement operation of the present embodiment is the same as that of the first embodiment, the description thereof is omitted.
After the coarse movement operation, the control unit 46 calculates the deviation between the current position recognized by the position sensor 17 and the first target position read out as described above, and eliminates this deviation, as in the first embodiment. As described above, the actuator driving unit 49 applies a control voltage to the piezoelectric actuator 36 to perform a fine movement operation.

Also in the axial fine movement mechanism 41 with the rotation mechanism of the present embodiment, as in the first embodiment, the displacement amounts of the outer ring 21a and the inner ring 23a on the constrained side that are half the displacement of the piezoelectric actuator 36 are The amount of fine movement displacement.
That is, the axial fine movement mechanism 41 with the rotation mechanism of this embodiment constrains the axial movement of the inner ring 23a of the angular ball bearings 20a, 20b opposed to each other by the inner ring engaging portion 29, and the inner ring 23a is interposed via the piezoelectric actuator 36. Since the pressure is applied to the piezoelectric actuator 36 so that a displacement of 2X is applied to the piezoelectric actuator 36, for example, when the piezoelectric actuator 36 is expanded by 2X, the pressing force generated by the expansion is controlled by the fine movement control. The inner ring 23b is pressed in addition to the preload load before the operation is performed, the inner ring 23b is moved in the axial direction (left in FIG. 10), and the gap 40 between the inner rings 23a and 23b acts.

  The displacement of the gap 40 is applied to the contact surface between the ball 25b and the outer ring raceway 22b and the inner ring raceway 24b and the contact surface between the ball 25a and the outer ring raceway 22a and the inner ring raceway 24a in addition to the preload before performing fine movement control. And the elastic ball bearings 20a and 20b are each displaced by X, the inner ring 23b is displaced by 2X in the axial direction, and the gap 40 is narrowed by 2X. Absorbs direction elongation.

As described above, the angular ball bearings 20a and 20b disposed opposite to each other absorb the displacement 2X of the gap 40 so as to be absorbed in units of X, so that when the force of the angular ball bearings 20a and 20b pressing each other is balanced, the housing Since the outer rings 21a and 21b whose axial movement is restrained by the inner peripheral surface of the shaft 27 are relatively displaced in the axial direction and the housing 27 is fixed to the base 5, the screw shaft 11 is axially moved (see FIG. 10) X displacement to the right). The movement of the screw shaft 11 in this case is absorbed by the contraction of the coupling 15 on the drive motor 14 side, and the movement of the shaft end on the opposite side is absorbed by the play of the support bearing 16.

As a result, the nut 12 screwed in the state where there is no play on the screw shaft 11 moves X in the axial direction, and the moving base 6 to which the nut 12 is fixed becomes the base 5 to which the housing 27 is fixed. On the other hand, X moves to the right in FIG. That is, the displacement amount of the outer ring 21 a and the inner ring 23 a on the restrained side which is half the displacement (expansion / contraction amount ) of the piezoelectric actuator 36 becomes the fine movement displacement amount of the movable table 6.

Oite this fine movement operation, control unit 46 performs feedback control based on the deviation in the same manner as in Example 1, to stop the moving platform 6 to the target position.
Since the subsequent operation is the same as that of the first embodiment, the description thereof is omitted.
As described above, the axial fine movement mechanism 41 with the rotation mechanism of the present embodiment causes the preload reaction force applied to the angular ball bearings 20a and 20b of the rear combination to act on the piezoelectric actuator 36 disposed on the inner rings 23a and 23b side. Since the coarse motion operation and the fine motion operation are performed while always applying a compressive load, there is no occurrence of breakage due to a tensile load, and there is no need to use a spring to avoid it.

Further, the bearing unit can be assembled in the same manner as the method of assembling the bearing unit only by using the housing 27 and the screw shaft 11 that are longer than the piezoelectric actuator 36, and can be easily assembled without paying special attention to the assembly of the piezoelectric actuator 36. The axial fine movement mechanism 41 with the rotation mechanism can be assembled.
Further, if the piezoelectric actuator 36 is incorporated into the screw shaft 11 with the outer peripheral surface of the fitting shaft 26 of the screw shaft 11 as a guide, the piezoelectric actuator 36 is automatically arranged on the same axis. It will not cause premature breakage.

Further, the axial fine movement mechanism 41 with the rotation mechanism of the present embodiment does not have a spring having a low rigidity as in the first embodiment, so that the piezoelectric actuator 36 having a very high rigidity with respect to a load in the compression direction and a high rigidity. By combining with a rigid spring member, the rigidity of the entire positioning device can be maintained substantially the same as that of a bearing unit that does not incorporate the piezoelectric actuator 36 both statically and dynamically, and stable at high speed and high response. it is as possible out to perform a fine movement behavior.

Furthermore, since the piezoelectric actuator 36 can be arranged coaxially with the screw shaft 11, the displacement of the piezoelectric actuator 36 can be a pure axial displacement, and a highly accurate fine movement operation can be performed.
As described above, in the present embodiment, the same effect as that of the first embodiment can be obtained also by disposing the piezoelectric actuator on the inner ring side of the angular ball bearings disposed to face each other.

  In addition to the above, in this embodiment, the piezoelectric actuator is hollow and fitted to the outer peripheral surface of the screw shaft so as to be arranged coaxially with the screw shaft. As a result, the bearing unit can be assembled by the same method as the method of assembling, and the axial fine movement mechanism with the rotation mechanism using the piezoelectric actuator can be easily assembled.

  Further, the outer peripheral surfaces of the outer rings of the two angular ball bearings arranged opposite to each other are fitted to the inner peripheral surface of the housing, and the movement of each outer ring in the axial direction is sandwiched between the outer ring engaging portion and the cover to the housing. In addition to fixing, the axial movement of one of the inner rings of the two angular ball bearings is constrained to the screw shaft by the inner ring locking portion, and the other is moved in the axial direction by the piezoelectric actuator, so that the control voltage Half of the displacement of the piezoelectric actuator due to the application can be made the displacement of the screw shaft, and the error of the displacement of the piezoelectric actuator can be halved to realize a highly accurate fine movement operation.

In addition, if a configuration similar to that of the present embodiment is configured using a piezoelectric actuator that is fitted to the outer peripheral surface of the nut, an axial fine movement mechanism with a rotation mechanism formed between the nut and the housing similar to that of the above-described fourth embodiment. Can act.
In the first to fourth embodiments, it has been described that the inner ring spacer is provided between the opposed inner rings to apply the preload, but the surface on the opposite side of the inner ring corresponds to half the width of the inner ring spacer. The inner rings may be brought into direct contact with each other by extending the length. In the fifth embodiment, a similar outer ring may be provided and brought into direct contact.

In each of the above embodiments, the inner ring spacer and the outer ring spacer are described as being provided. However, these are omitted, and the inner ring and the outer ring are directly tightened with a lock nut and a cover, and the piezoelectric actuator is brought into direct contact with the outer ring and the inner ring. It may be.
Furthermore, in each of the above-described embodiments, it has been described that preload is applied in advance to two rolling bearing devices arranged opposite to each other via a non-energized piezoelectric actuator. However, preload is not generated when the piezoelectric actuator is not energized. The piezoelectric actuator and the outer ring or the inner ring are opposed to each other through a gap, and a predetermined voltage is applied to the piezoelectric actuator when the positioning device is activated, for example, so that a predetermined preload is generated in the two rolling bearing devices arranged opposite to each other. May be. In this way, in order to give a predetermined preload to the two rolling bearing devices, for example, a so-called preload adjustment in which the axial length or the like of the outer ring spacer 37 of the first embodiment is precisely adjusted according to the amount of preload. Thus, precise preload adjustment can be easily performed only by applying a predetermined voltage.

Further, in each of the above embodiments, the rolling bearing device has been described as an angular ball bearing. However, the rolling bearing device is not limited to the angular ball bearing, and a preload is applied to the rolling bearing devices arranged oppositely such as a deep groove ball bearing and a tapered roller bearing. Anything can be used.
Furthermore, although two rolling bearing devices by one rolling bearing have been described as being opposed to each other, two sets of rolling bearing devices in which a plurality of rolling bearings are arranged in a parallel combination may be arranged opposite to each other. For example, two rolling bearing devices with one set of two on one side and one rolling bearing on the other may be arranged to face each other. For example, in FIG. 1 of the first embodiment, if one pair of rolling bearings is arranged on the right side and one set on the left side, the screw shaft moves about 1.2X in the left direction in FIG. Will be.

Further, in each of the above-described embodiments, the rolling bearing device of the axial fine movement mechanism with the rotation mechanism has been described as being used as a bearing for supporting the screw shaft of the coarse movement mechanism. Needless to say, the present invention can be applied to the combined rotational and axial fine movement mechanism.
Further, in each of the above embodiments, the feed screw device has been described as a ball screw device in which a screw shaft and a nut are screwed together via a ball. However, the feed screw device is not limited to the above, and the screw shaft and the nut It may be a sliding screw device for directly screwing.

  Furthermore, in each of the above embodiments, the feedback control is described as being performed during the fine movement operation. However, the feedback control is performed using the deviation between the current position recognized by the position sensor and the read target position during the coarse movement operation. The coarse movement operation may be stopped when the deviation falls within a predetermined range. In this way, the lead accuracy of the screw shaft can be corrected, the correction amount due to the fine movement operation of the piezoelectric actuator can be reduced, and there is no need to use a piezoelectric actuator having a larger expansion / contraction amount than necessary.

Sectional drawing which shows the axial direction fine-movement mechanism with a rotation mechanism of Example 1. FIG. The top view which shows the positioning device of Example 1. Explanatory drawing seen from the side which shows the positioning device of Example 1. FIG. Explanatory drawing seen from the side which shows the control apparatus of Example 1. FIG. Sectional drawing which shows the axial direction fine movement mechanism with a rotation mechanism of Example 2. Explanatory drawing seen from the side which shows the positioning device of Example 2. Sectional drawing which shows the axial direction fine movement mechanism with a rotation mechanism of Example 3. Sectional drawing which shows the axial direction fine movement mechanism with a rotation mechanism of Example 4. FIG. Explanatory drawing seen from the side which shows the positioning device of Example 4. Sectional drawing which shows the axial direction fine movement mechanism with a rotation mechanism of Example 5. Explanatory drawing showing manufacturer recommended example of piezoelectric actuator mounting

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Positioning device 2 Linear guide mechanism 3 Rail 4 Slider 4a Moving stand mounting surface 5 Base 6 Moving stand 10 Coarse moving mechanism 11 Screw shaft 11a Shaft track groove 12, 61 Nut 13 Ball screw device 14, 67 Drive motor 15, 68 Cup Ring 16 Support bearing 17 Position sensor 18 Scale 20a, 20b Angular contact ball bearing 21a, 21b Outer ring 22a, 22b Outer ring raceway 23a, 23b Inner ring 24a, 24b Inner ring raceway 25a, 25b Ball 26 Fitting shaft 27 Housing 27a, 27b Screw hole 29, 63 Inner ring locking part 30, 64 Inner ring spacer 31, 65 Inner ring spacer 32 Lock nut 33, 62 Screw part 34 Coupling mounting part 36, 50, 100 Piezoelectric actuator 36a Hollow part 37, 72 Outer ring spacer 38 Outer ring locking part 39 Cover 40 gap 41 Axial fine movement mechanism with rotation mechanism 45 Control device 46 Control unit 47 Storage unit 48 Motor drive unit 49 Actuator drive unit 51 Piston 52 Storage hole 53 Relief hole 54 Recessed hole 57 Presser plug 69 Fixing part 71 Outer ring spacer 73 Slip ring 74 Electrode ring 75 Fixed side electrode 76 Brush 101 Output shaft 102 Spring

Claims (10)

Two rolling bearing devices arranged to face each other and applied with a preload, a housing having an inner circumferential surface with which an outer circumferential surface of each outer ring of the rolling bearing device is fitted, and an inner circumferential surface of each inner ring of the rolling bearing device A shaft having an outer peripheral surface to be fitted, and a piezoelectric actuator arranged on one side in the axial direction of the two rolling bearing devices and extending and contracting in the axial direction according to a voltage applied from the outside,
On one side of the housing, a cover for pressing the end face of the piezoelectric actuator is provided by fastening to the housing by fastening means,
In the rolling bearing device on one side in the axial direction of the two rolling bearing devices, the outer ring is constrained in the axial direction via the piezoelectric actuator to the housing fitted with the outer peripheral surface thereof, and the inner ring is fitted. Affixed to the shaft in the axial direction,
In the rolling bearing device on the other side in the axial direction of the two rolling bearing devices, the outer ring is restrained in the axial direction on the housing fitted, and the inner ring is restrained in the axial direction on the fitted shaft. ,
The axial distance between the outer rings of the two rolling bearing devices to which the preload is applied is changed by a change in the preload accompanying expansion and contraction of the piezoelectric actuator,
The relative displacement amount in the axial direction of the outer ring and the inner ring of the other rolling bearing device on the other side is the relative movement amount of the shaft and the housing;
Fixing either the shaft or the housing in the axial direction ;
An axial fine movement device with a rotation mechanism , wherein the piezoelectric actuator is energized when the rotation of the rolling bearing device is stopped . In claim 1,
An axial fine movement device with a rotating mechanism, wherein a spacer having an outer diameter equivalent to that of the outer ring is disposed between the outer ring of the rolling bearing device on one side and the piezoelectric actuator. In claim 1 or claim 2,
An axial fine movement device with a rotating mechanism, wherein the inner rings of the two rolling bearings are restrained in the axial direction via a spacer. In any one of Claims 1 to 3,
An axial fine movement device with a rotation mechanism, wherein the preload is applied in advance in a state where the piezoelectric actuator is not energized. In any one of Claims 1 to 3,
An axial fine movement device with a rotation mechanism, wherein the preload is generated by applying a predetermined voltage to the piezoelectric actuator. In any one of Claims 1 thru | or 5,
An axial fine movement device with a rotation mechanism, wherein the piezoelectric actuator is a laminated type. In any one of Claims 1 thru | or 6,
An axial fine movement device with a rotation mechanism, wherein the piezoelectric actuator is hollow. In any one of Claims 1 thru | or 6,
An axial fine movement device with a rotation mechanism, wherein the piezoelectric actuator is solid and is disposed substantially on the axis of the rolling bearing device. In any one of Claims 1 thru | or 8,
An axial fine movement device with a rotation mechanism, wherein the rolling bearing devices arranged opposite to each other are arranged as a front combination. In any one of Claims 1 thru | or 8,
An axial fine movement device with a rotating mechanism, wherein the opposingly arranged rolling bearing devices are arranged as a back surface combination.

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