JPH06113570A - Direct driver - Google Patents

Abstract

PURPOSE:To obtain a direct driver having simplified structure in which power is saved while enhancing durability and suppressing noise by providing an ultrasonic motor which rotates a slide nut through a threaded rotary shaft. CONSTITUTION:The direct driver 38 comprises a threaded shaft 22, a slide nut 24, and an ultrasonic motor 44 wherein the slide nut 24 is rotated smoothly through a plurality of balls by means of the threaded rotary shaft 22. The threaded shaft 22 is inserted loosely into a through hole 70 made through a stator holder 48 and fixed with the ultrasonic motor 44. When a predetermined voltage is applied on the ultrasonic motor 44, a second piezoelectric element 42 oscillates in peripheral direction to produce rotary drive force whereas a first piezoelectric element 40 expands and shrinks in the axial direction thus controlling contact between a stator head 46 and the slide nut 24. Since the slide nut is driven directly, no gear mechanism is required and durability is enhanced through simple mechanism resulting in a silent direct driver in which energy saving is achieved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear motion device used in various grinders, lathes, conveyors, printers and the like.

[0002]

2. Description of the Related Art Various linear motion devices are used to drive linear motion systems in various grinding machines, lathes, conveyors, printers and the like. Above all, in a linear motion device using a ball screw, a high transmission efficiency can be obtained because the screw shaft and the slide nut are in rolling contact with each other via balls. Moreover, since it can withstand high speed rotation with simple lubrication and has excellent wear resistance, it enables high speed and maintenance-free operation of the machine. FIG. 4 shows an example of a conveyor using a linear motion device using a ball screw. The carrier 10 has a base 12
A side plate 13 formed at an end of the base 12, and a base 12
Guide rails 14, 14 formed along the longitudinal direction of the
And a plate-like slider 18 that moves on the guide rail 14 via the guides 16, 16, 16, and 16, and a linear motion device 20 that generates a driving force for moving the slider 18. As a carrier, a slider 18 may be further provided with a carrier plate that works together with the slider 18, or the slider 1 may be used.
8 itself is used as a carrier plate. The linear motion device 20 includes a screw shaft 22 provided in parallel with the guide rail 14, a slide nut 24 provided on the screw shaft 22, and an electromagnetic motor 26 for rotating the slide nut 24. The linear motion device 20 will be described in detail with reference to FIG. Slide nut 24
Has a cylindrical shape, and a screw shaft 22 penetrates the central portion in the axial direction. Inside the slide nut 24, a ball tube 3 in which a plurality of balls 28, 28, ...
0 is provided, and the ball 28 circulates in the ball rolling groove 52 of the threaded screw shaft 22 and the ball tube 30. Slide nut 24 is bearing 34
It is rotatably supported by the support plate 36 via the support plate 36, and the support plate 36 is fixed to the lower surface of the slider 18. An electromagnetic motor 26 is fixed to the slider 18, and the electromagnetic motor 26
Attaches the slide nut 24 to the screw shaft 22 via the rotor 32.
Is rotated about.

The linear motion device 20 and the linear motion device 20 having this structure.
In the transporting machine 10 provided with, the slide nut 24 rotates around the screw shaft 22 by operating the electromagnetic motor 26 to rotate the rotor 32 that is in contact with the outer peripheral surface of the slide nut 24. When the slide nut 24 rotates, the balls 28 loaded inside the slide nut 24
Is the ball rolling groove 52 of the screw shaft 22 and the ball tube 3
It rolls in 0 and circulates. Ball 28 is screw shaft 2 in sequence
The ball is rolled in the second ball rolling groove 52 while receiving a load in the axial direction, and the slide nut 24 moves along the screw shaft 22. Therefore, the support plate 36 that rotatably supports the slide nut 24 also moves in the axial direction of the screw shaft 22, so that the slider 18 to which it is fixed moves linearly in the axial direction of the screw shaft 22. .

[0004]

However, in the linear motion device 20 described above, since the slide nut 24 is rotated by the electromagnetic motor 26, the transmission loss of the driving force is large when the slide nut 24 is rotated, and FIG. Although not shown in FIG. 3, since the gear mechanism is actually provided, the mechanism of the linear motion device 20 is complicated, the number of parts is increased and the size is increased, and the cost is increased. . Furthermore, the wear was severe and the durability performance was poor. Further, when the slider 18 is stationary, the slide nut 24 is not rotated so that the slider 18 does not move. Therefore, a voltage is applied to the electromagnetic motor 26 to generate a holding force. Even when the slider 18 is stationary and fixed, applying a voltage to the electromagnetic motor 26 consumes very useless energy.

The present invention has been made to solve the above-mentioned problems, and the performance of a linear motion device is not deteriorated.
It is intended to provide a linear motion device that simplifies the mechanism, improves durability, and achieves quietness and power saving.

[0006]

The linear motion device of the present invention comprises:
(1) A screw shaft having a spiral ball rolling groove formed therein, and (2) a ball rolling in the ball rolling groove is loaded, and the ball rolls in the ball rolling groove. A slide nut attached to the screw shaft so as to be movable in the axial direction of the screw shaft; (3) a first piezoelectric element that is substantially cylindrical and that vibrates in the axial direction; and a second piezoelectric element that vibrates in the circumferential direction. And an ultrasonic motor that rotates the slide nut with the screw shaft as a rotation shaft.

[0007]

In the linear motion device of the present invention, the ball loaded in the slide nut is rotated in the ball rolling groove formed on the screw shaft by rotating the slide nut with the screw shaft by the ultrasonic motor. It rolls and circulates while receiving a directional load, so that the slide nut itself moves linearly in the axial direction of the screw shaft. An ultrasonic motor uses a composite oscillator ultrasonic motor having a first piezoelectric element that vibrates in the axial direction and a second piezoelectric element that vibrates in the circumferential direction, and the center thereof penetrates in the axial direction. By loosely inserting the screw shaft into the through hole, the ultrasonic motor can be attached to the screw shaft, the mounting space can be made extremely small, and the size can be dramatically reduced. Since the slide nut pressed against the pressure contact surface of the ultrasonic motor is directly rotated, the driving force transmission mechanism is simple, the driving force transmission loss is small, and the durability is high. Furthermore, the resolution is very high due to the characteristics of the ultrasonic motor. Further, since the ultrasonic motor is constantly in pressure contact with the slide nut, free rotation of the slide nut is suppressed even when the ultrasonic motor is not driven, that is, even when no voltage is applied. Therefore, it is not necessary to apply a voltage for fixing the slide nut, and energy can be saved.

[0008]

Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited thereto. A linear motion device that is an embodiment of the present invention will be described with reference to FIGS. The linear motion device 38 is roughly composed of a screw shaft 22, a slide nut 24, and an ultrasonic motor 44.

The screw shaft 22 is as shown in FIG.
A cylindrical shaft along the moving direction of the slider 18,
A ball rolling groove 52 continuous in a spiral shape is threaded.
The ball rolling groove 52 is preferably manufactured by rolling, because of high processing accuracy.

The slide nut 24 is a cylindrical member made of resin, alloy or the like, and the screw shaft 22 penetrates through an internal hole formed in the axial direction of the slide nut 24. Also, slide nut 2
4 is loaded with a plurality of balls 28, and the slide nut 24 is attached to the screw shaft 22, so that the balls 28 are attached to the screw shaft 2
About half of each ball enters into the ball rolling groove 52 of No.2. Further, the slide nut 24 is provided with a ball tube 30 in which the ball 28 rolls. The ball 28 circulates in the ball rolling groove 52 and the ball tube 30 located inside the slide nut 24. Has become. The slide nut 24 comes into contact with the screw shaft 22 via the plurality of balls 28, and the slide nut 24 smoothly rotates about the screw shaft 22 as a rotation shaft. However, in order for the slide nut 24 to rotate, the ball 28
Needs to roll in the ball rolling groove 52 and the ball tube 30. Brush rails 56, 56 are provided at both ends of the slide nut 24. The brush rail 56 has a dustproof function of cleaning the ball rolling groove 52 of the screw shaft 22 and preventing foreign matter from coming into contact with the ball 28. An annular plate 36 is rotatably provided on the slide nut 24 via a bearing 88, and the annular plate 36 supports the slide nut 24. The annular plate 36 is supported by a support rod 66 fixed to a case 60 described later so as to be movable in the axial direction. Therefore, the slide nut 24 is attached to the case 60 via the bearing 88, the annular plate 36, and the support rod 66.
Supported by.

The ultrasonic motor 44 includes a hollow stator holder 48, a stator head 46, a first piezoelectric element 40, and a second piezoelectric element 40.
It is composed of a piezoelectric element 42 and a stator bottom 50. The pressure contact surface 72, which is the end surface of the stator head 46, is in contact with the slide nut 24. The stator holder 48 is formed with a through hole 70 penetrating the center thereof in the axial direction, and the screw shaft 22 is loosely inserted into the through hole 70, and the ultrasonic motor 44 is attached to the screw shaft 22. The stator holder 48 is formed with a flange 49 protruding outward at the position of the vibration node of the ultrasonic motor 44. The first piezoelectric element 40 and the second piezoelectric element 42 are ring-shaped and are made of PZT.
A laminated piezoelectric actuator or a single-plate piezoelectric ceramic made of (lead zirconate titanate) is used. These piezoelectric elements 40 and 42 are connected to a power supply device (not shown) that generates a high frequency current, and when a predetermined AC voltage is applied, the first piezoelectric element 40 vibrates in the axial direction of the ultrasonic motor 44, The second piezoelectric element 42 vibrates in the circumferential direction of the ultrasonic motor 44, and a combined wave formed by combining these vibrations rotates the slide nut 24 that is in pressure contact with the pressure contact surface 72 of the ultrasonic motor 44. A friction material is interposed between the pressure contact surface 72 and the end surface 73 of the slide nut 24 as needed. The friction material is attached to the pressure contact surface 72, the end surface 73, or both surfaces thereof. A ring-shaped rotor interlocking with the slide nut 24 may be interposed between the pressure contact surface 72 and the slide nut 24. In this case, when a driving force is generated by the ultrasonic motor 44, the rotor pressed by the pressure contact surface 72 rotates, and the slide nut 24 rotates in conjunction with the rotating rotor.

The ultrasonic motor 44 and the slide nut 24 are housed in a case 60. Case through holes 62 and 64 are formed on both end surfaces of the case 60, and the screw shaft 22 penetrates the case through holes 62 and 64. Case 60
A support rod 66 is provided along the inner wall of the case, and the support rod 66 is fixed to the case 60 by a nut 68. The support rod 66 has an annular plate through hole 54 formed in the annular plate 36.
And is fitted in a hole formed in the flange 49, and the ultrasonic motor 44 is supported and fixed to the case 60 by a support rod 66. The support rod 66 is loosely inserted in the annular plate through hole 54, and the annular plate 36 is supported by the support rod 66 movably in the axial direction of the screw shaft 22. The support rod 66 is
Although FIG. 1 shows two examples, the number may be three or more, and is not limited to the rod shape as long as the ultrasonic motor 44 can be supported and fixed,
For example, it may be cylindrical. A biasing means 58 is provided on the support rod 66 at a position between the inside of the end surface of the case 60 and the annular plate 36. The biasing means 58 may be any means as long as it biases the annular plate 36 toward the ultrasonic motor 44 side, and a spring member can be applied. Toric plate 3
6 is biased to the ultrasonic motor 44 side by the biasing means 58, and the slide nut 24 connected to the annular plate 36 via the bearing 88 is also biased to the ultrasonic motor 44 side. Therefore, the end surface 73 of the slide nut 24 is in pressure contact with the pressure contact surface 72 of the ultrasonic motor 44. That is, the slide nut 24, which is rotatably supported by the annular plate 36, is rotatably pressed against the pressure contact surface 72 of the ultrasonic motor 44 with the screw shaft 22 as the rotation axis. Biasing means 5
The structure and position of the slide nut 24 are not limited as long as the slide nut 24 and the ultrasonic motor 44 are brought into pressure contact with each other, and an elastic material such as rubber is used, or the screw shaft 22
Is used to press the slide nut 24 directly by using a spring member arranged so as to penetrate inside, or to attach it to the ultrasonic motor 44 to urge the ultrasonic motor 44 toward the slide nut 24 side. I don't care. It is desirable to provide brush rails like those provided in the slide nut 24 in the case through holes 62 and 64 to prevent foreign matter from entering the case 60. A flat plate-shaped slider 18 as shown in FIG. 4 can be connected to and interlocked with the case 60.

To operate the linear motion device 38 having the above structure, a predetermined alternating current is applied to the ultrasonic motor 44. In the ultrasonic motor 44, the second piezoelectric element 42 vibrates in the circumferential direction to generate a rotational driving force, and the first piezoelectric element 40 expands and contracts in the axial direction to control contact between the stator head 46 and the slide nut 24. Has become. That is, the spring member 58
When a voltage is applied to the second piezoelectric element 42 in a state where the stator head 46 and the slide nut 24 are pressed and contacted by the spring force of the slide nut 24, the torsion force of the second piezoelectric element 42 causes the slide nut 24 to rotate the screw shaft 22. As a small angle to rotate. When the first piezoelectric element 40 contracts after rotation and the pressing force of the slide nut 24 against the stator head 46 is reduced, the twist amount of the second piezoelectric element 42 is offset and disappears. Here, when the first piezoelectric element expands to increase the pressing force between the pressure contact surface 72 and the slide nut 24 again and apply a voltage to the second piezoelectric element 42, the slide nut 24 rotates again by a minute angle. By repeatedly performing the elliptic motion that is a combination of the vibration of the second piezoelectric element 42 and the vibration of the first piezoelectric element 40, the slide nut 24
Can be continuously rotated in a fixed direction. The rotational driving force generated by the ultrasonic motor 44 has a high torque even at a low speed.

When the slide nut 24 rotates about the screw shaft 22 as a rotating shaft by the driving force of the ultrasonic motor 44,
The balls 28 loaded therein roll in the ball rolling grooves 52. The ball 28 in the ball rolling groove 52 rolls in the ball rolling groove 52, is fed into the ball tube 30, and is fed into the ball tube 30.
8 is again fed into the ball rolling groove 52 from the opposite side. Therefore, the plurality of balls 28 roll and circulate in the ball rolling groove 52 and the ball tube 30 one after another. At this time, the balls 28 roll while receiving the axial load of the screw shaft 22, so that the slide nut 24 itself moves linearly in the axial direction of the screw shaft 22 along with the rolling of the balls 28 in the ball rolling groove 52. Will be done. The spring member 58 is a biasing means for effectively transmitting the rotational driving force generated by the vibration of the first piezoelectric element 40 and the second piezoelectric element 42 to the slide nut 24. When the slide nut 24 moves in the direction A in FIG.
The circular plate 36 that is interlocked with the axial direction of the screw shaft 22 also moves via the circular plate 36, and the circular plate 36 compresses the spring member 58, and after the compression force on the spring member 58 and the elastic force of the spring member 58 are balanced. Causes the case 60 to move in the A direction in conjunction with the movement of the slide nut 24 in the A direction. Further, when the rotation direction of the slide nut 24 is the opposite direction to the above and the slide nut 24 moves in the B direction, the ultrasonic motor 44 pressing and touching the slide nut 24 has a force to move in the B direction. When the ultrasonic motor 44 starts moving in the B direction, the case 60 also moves in the B direction in conjunction with the support rod 66 connected to the ultrasonic motor 44 by the flange 49. Therefore, when the slide nut 24 rotates about the screw shaft 22 as the rotation axis, the slide nut 24 linearly moves along the axial direction of the screw shaft 22 according to the rotation direction regardless of the rotation direction, and slides. Whether the nut 24 linearly moves in the A or B direction, the case 60 also interlocks with the slide nut 24 along the axial direction of the screw shaft 22. Therefore, since the case 60 linearly moves along the screw shaft 22, if the slider 18 as shown in FIG. 4 is connected so as to be interlocked with the case 60, the slider 18 will generate a rotational driving force generated by the ultrasonic motor 44. Thus, the screw shaft 22 is linearly moved along the axial direction. Therefore, the linear motion device 38 of the present embodiment can be applied as a drive device for the carrier machine 10 as shown in FIG.
In this case, the case 60 may be provided without further providing a carrier plate that interlocks with the slider 18, or without providing the slider 18.
Needless to say, it may be used as a carrier plate.

A conveying device using a linear motion device using an electromagnetic motor as a drive source and a conveying device using a linear motion device using an ultrasonic motor according to this embodiment as a drive source are manufactured. The speed was measured. As a result, the linear motion device using the ultrasonic motor according to the present embodiment was comparable to the linear motion device using the electromagnetic motor.

Further, when the slider 18 is stationary, it is necessary to prevent the slide nut 24 from rotating in order to prevent the slider 18 from moving. However, when an electromagnetic motor is used, a voltage is applied to the electromagnetic motor. Holding force must be generated (5kgf or more) by continuing. However, according to the linear motion device of the present invention which uses the ultrasonic motor, the ultrasonic motor is constantly in pressure contact with the slide nut 24 by the biasing means.
The pressure contact force prevents the slide nut 24 from rotating even if the ultrasonic motor is not electrically operated. That is, when the slider 18 is stationary, the rotation of the slide nut 24 is suppressed without applying a voltage to the ultrasonic motor 44, so that energy saving can be achieved. Further, since the slide nut 24 is directly driven to rotate by using the ultrasonic motor 44, a gear mechanism or the like is not required, and the mechanism is simple as a linear motion device, and the size and weight can be reduced. You can Therefore, the durability performance is improved, the generated sound is small, and the quietness is high. Particularly, in this embodiment, a substantially cylindrical composite vibrator ultrasonic motor having a first piezoelectric element and a second piezoelectric element is used to generate the rotational driving force, and the center of the ultrasonic motor is Through hole 70 penetrating in the axial direction
Since the ultrasonic motor is attached by inserting and penetrating the screw shaft 22 into the, the space required is extremely small, and the miniaturization is greatly improved. Further, since the ultrasonic motor 44 having high resolution is used, the accuracy of the linear motion device is further improved. Further, since the ultrasonic motor 44 is used instead of the electromagnetic motor,
There is no effect of magnetic action on the outside, and it can be used for transportation of magnetic materials. When used in a carrier machine or the like, it is possible to enhance the carrying capacity by mounting a plurality of linear motion devices instead of one.

The linear motion device of the present invention can be used not only for the transporter as shown in FIG. 4 but also for various kinds of grinding machines, lathes, printers, or any other mechanism that requires a linear driving force.

Another example of the slide nut will be described with reference to FIG. The slide nut 80 shown in FIG. 3 is a substantially cylindrical member made of resin, alloy, or the like, and the screw shaft 22 penetrates the inner hole thereof. Further, the slide nut 80 is loaded with a plurality of balls 28, and the slide nut 80 is attached to the screw shaft 2.
By attaching the ball 28 to the ball 2, about half of each ball 28 enters the ball rolling groove 52 of the screw shaft 22. The slide nut 80 has the ball tube 3 shown in FIG.
0 is not provided, instead the ball 2
End caps 82, 83 in which a groove for rolling 8 is formed
And a transfer pipe 84 communicating with the groove formed in the end caps 82 and 83 is formed in the slide nut 80. The ball 28 circulates in the ball rolling groove 52 located inside the slide nut 24 and the transfer pipe 84. A brush rail 56 is further provided at one end of the slide nut 80. The brush rail 56 has a dustproof function of cleaning the ball rolling groove 52 of the screw shaft 22 and preventing foreign matter from coming into contact with the ball 28.

The slide nut 80 comes into contact with the screw shaft 22 through the plurality of balls 28, and the slide nut 80 smoothly rotates about the screw shaft 22 as a rotation shaft.
However, in order for the slide nut 80 to rotate, the ball 2
It is necessary that 8 rolls in the ball rolling groove 52 and the transfer pipe 84.

In the slide nut 80 of this example,
The ball 28 is scooped up from the ball rolling groove 52 by the end cap 82 which is a rigid body and sent out to the transfer pipe 84. The strength is higher than that using a ball tube,
It is stable and can handle high-speed rotation, and is highly quiet.

Since the linear motion device of the present invention rotates the slide nut by the driving force of the ultrasonic linear motor and linearly moves on the screw shaft, the slide nut has ultrasonic waves at the end. Any commercially available ball screw can be applied as long as it can be pressed against the motor and can be rotationally driven by the ultrasonic motor.

[0022]

According to the linear motion device of the present invention, the ball in the slide nut is formed on the screw shaft by rotating the slide nut attached to the screw shaft with an ultrasonic motor of small size, light weight and simple structure. The slide nut moves linearly on the screw shaft by rolling and circulating in the rolling groove.Since the slide nut is directly driven by using an ultrasonic motor, no gear mechanism is required. The mechanism of the linear motion device is simple, and it is possible to reduce the size and weight. Therefore, the durability performance is improved, the generated sound is small,
It is highly quiet. Particularly, in the present invention, a substantially cylindrical composite vibrator type ultrasonic motor having a first piezoelectric element and a second piezoelectric element is used to generate the rotational driving force, and the center of the ultrasonic motor is used as an axis. Since the ultrasonic motor is attached by inserting and penetrating the screw shaft into the through hole penetrating in the direction, the space required is very small and the miniaturization is greatly improved. Further, since the ultrasonic motor has a high resolution, it achieves energy saving as a linear motion device and further improves accuracy. Further, since the ultrasonic motor is used instead of the electromagnetic motor, there is no influence of the magnetic action on the outside, and it can be used for carrying magnetic materials and the like.

Further, since the ultrasonic motor is constantly in pressure contact with the slide nut by the biasing means, even when the ultrasonic motor is not driven without being applied with a voltage, the ultrasonic motor is driven by the biasing means. The free rotation of the slide nut is suppressed by the pressure contact force of the sonic motor, and the free movement of the slider that is interlocked with the slide nut during linear movement can be suppressed. Therefore, it is not necessary to apply a voltage when the slider is stationary, and energy can be saved.

[Brief description of drawings]

FIG. 1 is a side view of a linear motion device according to an embodiment.

FIG. 2 is a sectional view of a main part of a linear motion device according to the present embodiment.

FIG. 3 is a sectional view of a slide nut of another mode.

FIG. 4 is a perspective view of a carrier.

FIG. 5 is a schematic side view of a linear motion device of a conventional example.

[Explanation of symbols]

 20 Linear Motion Device 22 Screw Shaft 24 Slide Nut 28 Ball 30 Ball Tube 38 Linear Motion Device 40 Piezoelectric Element 42 Piezoelectric Element 44 Ultrasonic Motor 52 Ball Rolling Groove 80 Slide Nut

Claims (1)

[Claims] 1. A screw shaft having a ball rolling groove formed in a spiral shape and a ball rolling in the ball rolling groove are loaded, and the ball rolls in the ball rolling groove. A slide nut attached to the screw shaft so as to be movable in the axial direction of the screw shaft, a first cylinder-shaped first piezoelectric element that vibrates in the axial direction, and a second piezoelectric element that vibrates in the circumferential direction. And a ultrasonic motor that rotates the slide nut with the screw shaft as a rotation shaft.