JP4195939B2 - Levitation / adsorption force generator - Google Patents

Description

  The present invention relates to a technique for generating a levitation force or an adsorption force between two members using traveling waves.

  Most machines are composed of two or more components combined. When one of the two members combined is moved relative to the other (for example, rotational motion, slide motion), if the frictional force acting between the two members is large, precise positioning and feeding operations become difficult. In addition, problems such as wear of sliding surfaces of both members and seizure due to frictional heat occur. On the other hand, if one of the two members capable of relative movement is positioned at a predetermined position with respect to the other and the frictional force acting between the two members is too small, the positional relationship between the two members is destroyed by a small external force. For this reason, various bearings that realize smooth movement and rotation with extremely small frictional force, and conversely, devices that clamp with increased frictional force have been developed. In addition, for precision machine elements, devices have been developed that correct geometrical errors of guide surfaces and error motions caused by external forces.

As an apparatus for controlling the frictional force acting between two members, for example, the other member (shaft) is supported in a non-contact manner with respect to one member (bearing), and the friction acting between the two members Bearing devices that reduce the force are known. As this type of bearing device, a hydrostatic bearing device (for example, Non-Patent Document 1), a hydrodynamic bearing device (for example, Non-Patent Document 2), a squeeze film bearing device (for example, Non-Patent Document 3), and the like have been developed. ing.
In a hydrostatic bearing device, a compressed fluid (for example, air, oil, etc.) is supplied to a gap between a bearing (one member) and a shaft (the other member), and the shaft is supported in a non-contact manner by the pressure. In this hydrostatic bearing device, a peripheral device (for example, a compressor) for supplying a compressed fluid to the gap between the bearing and the shaft is required, so that the device is large and expensive. In addition, it is necessary to install a long pipe on a moving table or the like, which may hinder movement.
In a hydrodynamic bearing device, when the bearing or shaft moves, pressure is generated by the wedge effect in which the fluid sandwiched between the bearings and the shaft is carried by the rotation of the shaft into a narrow gap, and the shaft is brought into contact with the pressure. To support. In this hydrodynamic bearing device, when the rotational speed of the shaft decreases, the pressure generated by the wedge effect decreases, and the shaft and the bearing come into contact with each other.
In the squeeze film bearing device, vibration in the support direction is applied to the compressible fluid film, and the shaft is supported in a non-contact manner by pressure due to the squeeze film effect. In this squeeze film bearing device, since the pressure obtained by the squeeze film effect is low, sufficient load capacity and rigidity cannot be obtained.
As is clear from the above, in the conventional technology, in order to realize a bearing that has practically extremely low frictional force, piping must be installed using a peripheral device such as a compressor, and error motion There is a problem that an additional device is required to correct the angle and perform clamping after positioning.
Aoyama Fujiro, “Hydrostatic Bearings-Design and Application”, Industrial Research Committee (1990) Junichi Jugo, “Gas bearings-from design to production”, Kyoritsu Publishing Co., Ltd. (1984) Yoshika Narika, Abu Yoshiro, “Dynamic Pressure Squeeze Air Guide Surface Using Piezoelectric Elements”, Tripodologist (July 1991), p. 543-548

  The present invention has been made in view of the above circumstances, and it is possible to extremely reduce the frictional force acting between two members without using a peripheral device such as a compressor. It is an object of the present invention to provide a technique capable of freely controlling the force acting between two members over a wide range until the occurrence of the above.

In the present invention, by generating a traveling wave on the surface of at least one of the two members, the frictional force acting between the two members can be freely controlled. That is, the device of the present invention is provided on at least one of the first member, the second member facing the first member, the first member, and the second member, An actuator that generates a traveling wave on the surface of the other member. The actuator generates a traveling wave on the surface of the other member with respect to the one member, thereby exerting a force on the fluid between the first member and the second member, and the first member and the second member. A levitation force or adsorption force is generated between the member and the other member.
In this apparatus, a traveling wave is generated on the surface of the other member by the actuator with respect to one member, thereby generating a levitation force or an adsorption force between the two members. When a levitation force is generated between the two members, the frictional force acting between the two members becomes extremely small. Further, when an attracting force is generated between the two members, a frictional force acting between the two members is increased.
In this apparatus, since it is only necessary to provide an actuator on at least one of the two members, peripheral devices such as a compressor and piping are not required. Further, the levitation force or adsorption force generated by the traveling wave can be controlled by the vibration intensity and frequency. Therefore, according to this device, the frictional force acting between the two members can be extremely reduced without using peripheral devices such as a compressor and piping, and the frictional force acting between the two members can be increased. Thus, the other member can be clamped to one member, and the levitating force can be controlled to correct the error motion.

  In the above apparatus, a traveling wave is generated from the outside to the inside of the surface of at least one of the first member and the second member, so that the surface floats between the first member and the second member. Can generate power. That is, when a traveling wave is generated from the outside toward the inside on the surface of at least one of the first member and the second member, the fluid pressure increases at the center of the first member and the second member. A levitation force is generated between the first member and the second member.

When a levitation force is generated between the first member and the second member, it is preferable that the traveling wave generated by the actuator is absorbed in the central portion of the first member and the second member. According to such a configuration, the traveling wave traveling from the outside to the inside is prevented from being reflected at the central portion, and a levitation force can be effectively generated between the two members.
The above-described device is a support device that supports the second member in a non-contact manner with respect to the first member by a levitation force generated between the first member and the second member (for example, a rotary bearing device or an opposing device). It can be applied to a type and gravity balance type linear motion guide device).

  Alternatively, an attraction force is generated between the first member and the second member by generating a traveling wave on the surface of at least one of the first member and the second member from the inside toward the outside. be able to. That is, when a traveling wave is generated on the surface of at least one of the first member and the second member from the inside to the outside, the fluid is discharged from between the first member and the second member (the central portion). A negative pressure), an adsorption force is generated between the two members.

  The present invention also provides a novel method for generating a levitation force or an adsorption force between a first member and a second member. That is, the method of the present invention applies a force to the fluid between the first member and the second member by generating a traveling wave on the surface of the second member with respect to the first member, A levitation force or an adsorption force is generated between the first member and the second member.

The principle of the levitation / adsorption force generator using traveling waves according to an embodiment of the present invention will be described with reference to FIG. FIG. 5 schematically shows a state in which a levitation force is generated between the two members 12 and 14 by the traveling wave.
As shown in FIG. 5, the levitation / adsorption force generator 10 of the present embodiment includes a first member (for example, a bearing) 12 and a second member (for example, a shaft or a guide surface) 14. The second member 14 has a guide surface 14a. In the case shown in FIG. 5, the guide surface 14a is a smooth flat surface, and its shape is not changed.
The first member 12 is a plate-like member (for example, a disk, a square plate, etc.), and is disposed at a position facing the second member 14. The first member 12 has a bearing surface 12a (for example, a flat surface, a cylindrical surface, a spherical surface, a conical surface, etc.), and the bearing surface 12a faces a guide surface 14a having the same surface shape. The first member 12 includes a plurality of actuators 18a, 18b,. The plurality of actuators 18a, 18b,... Are arranged at predetermined intervals in the circumferential direction from the center of the first member 12, and are arranged at predetermined intervals in the radial direction (that is, the actuators 18a, 18b,. Is arranged radially from the center of the first member 12).

  When the actuators 18a, 18b,... Are driven, the shape of the bearing surface 12a changes, and a traveling wave can be generated from the outer peripheral portion of the bearing surface 12a toward the center portion. That is, with the volume change between the bearing surface 12a and the guide surface 14a, the fluid receives a force from the outer peripheral portion toward the central portion. As a result, the pressure at the central portion of the bearing surface 12a is increased, a levitation force is generated between the first member 12 and the second member 14, and the first member 12 is lifted from the second member 14. Thereby, the frictional force which acts between the 1st member 12 and the 2nd member 14 can be made very small.

Note that when the flying height of the first member 12 increases, the gap between the bearing surface 12a and the guide surface 14a increases, so that fluid easily flows out between the bearing surface 12a and the guide surface 14a. For this reason, the pressure of the fluid between the bearing surface 12a and the guide surface 14a falls, and the flying height becomes small. Therefore, the flying height of the first member 12 is determined at a position where the fluid pressure and the fluid outflow amount are balanced.
Further, when a load acts on the first member 12 from the upper side to the lower side, the gap between the bearing surface 12a and the guide surface 14a becomes small, so that it is difficult for fluid to flow out between the bearing surface 12a and the guide surface 14a. For this reason, the pressure of the fluid between the bearing surface 12a and the guide surface 14a rises, and the force which supports the 1st member 12 increases. That is, it has a restoring force necessary as a bearing.
Furthermore, when a load acts on the eccentric position of the first member 12, the gap between the bearing surface 12a and the guide surface 14a is reduced on the side where a large load acts, and the pressure of the fluid acting on the bearing surface 12a is high. Become. On the other hand, on the side where a small load acts, a gap between the bearing surface 12a and the guide surface 14a is opened, and fluid easily flows out between the bearing surface 12a and the guide surface 14a, and the pressure of the fluid acting on the bearing surface 12a is increased. Lower. Since the fluid has viscous resistance and it is not easy to move from the high pressure side to the low pressure side, the first member 12 remains on the second member 14 even if a load acts on the eccentric position of the first member 12. It is maintained in a non-contact state (that is, it has moment resistance).

  Further, the traveling waves can be generated from the center portion of the bearing surface 12a toward the outer peripheral portion by driving the actuators 18a, 18b,. That is, the fluid is conveyed from the central portion to the outer peripheral portion in accordance with the volume change between the bearing surface 12a and the guide surface 14a. As a result, the fluid between the bearing surface 12a and the guide surface 14a is discharged, and the first member 12 is adsorbed by the second member 14 (an adsorbing force is generated therebetween). As a result, the frictional force acting between the first member 12 and the second member 14 can be extremely increased.

Here, a method for generating a traveling wave on the surface of the bearing surface will be briefly described. FIG. 6 is a diagram schematically showing a method of generating a traveling wave by forced vibration. In FIG. 6, a metal plate 22 is disposed so as to face the guide surface 20a. Three piezoelectric elements (not shown) are arranged on the metal plate 22 at equal intervals L, and the metal plate 22 is forcibly displaced by the piezoelectric elements. Here, when each piezoelectric element is driven with an equal phase difference α (for example, when each piezoelectric element is driven with sin (θ + α), sin θ, sin (θ−α)), the phase is shifted to the bearing surface 22a from the phase advance side. A traveling wave toward the delay side is generated.
Therefore, in the above-described embodiment, in order to generate a traveling wave on the bearing surface 12a and obtain a fluid driving force, for example, three piezoelectric elements are arranged at an equal distance L in the circumferential direction and the radial direction of the first member 12. To do. When a levitation force is generated between the bearing surface 12a and the guide surface 14a, advancing from the outer peripheral side toward the center by causing phase advance vibration, phase zero vibration, and phase delay vibration from the outer peripheral side toward the center. Generate a wave. On the other hand, when an adsorption force is generated between the bearing surface 12a and the guide surface 14a, a traveling wave from the center toward the outer periphery is generated by causing phase advance vibration, phase zero vibration, and phase delay vibration from the center toward the outer periphery. generate.

  Note that the method of generating the traveling wave is not limited to the above-described method using forced vibration, and for example, the traveling wave can be generated using a resonance phenomenon. When a traveling wave is generated from the outer periphery of the first member 12 toward the center using the resonance phenomenon, vibration is generated on the outer periphery of the first member 12 by a vibrator (for example, a bolted Langevin vibrator). At this time, the first member 12 is designed to be resonant so that the wave propagates radially. A vibrator (for example, a bolt-clamped Langevin vibrator) is also arranged at the center or the center side of the first member 12, and the propagating traveling wave is converted into electric energy or the like and consumed by load resistance or the like. Cancels the traveling wave propagated by the vibrator on the center side. Also by such a method, a traveling wave from the outer periphery of the first member 12 toward the center can be generated. When a traveling wave from the center of the first member 12 toward the outer periphery is generated, vibration is generated by the center or center-side vibrator and the traveling wave propagated by the outer-side vibrator is absorbed. That's fine.

The above-described levitation / adsorption force generator 10 generates a traveling wave on the surface of the bearing surface 12a by driving the actuators 18a, 18b,... There is no need to supply fluid.
Further, a traveling wave can be generated even when the first member 12 and the second member 14 are stationary, and a levitation force or an adsorption force can be generated between the first member 12 and the second member 14. it can.
Further, the levitation force or adsorption force acting between the first member 12 and the second member 14 varies depending on the amplitude and / or frequency of the traveling wave (that is, the unit time of the fluid to be conveyed by the traveling wave) Depending on the volume per unit). Therefore, by controlling the amplitude and / or frequency of the traveling wave, the levitation force or adsorption force acting between the first member 12 and the second member 14 can be arbitrarily controlled. For this reason, it can be adjusted to an appropriate levitation force or adsorption force according to the application.

  In the above-described embodiment, the shape of the guide surface 14a of the second member 14 is not changed, but the guide surface 14a may be vibrated according to the vibration of the bearing surface 12a of the first member 12. . Thereby, the amplitude of the vibration of the guide surface 14a with respect to the bearing surface 12a can be increased, and a larger levitation force or adsorption force can be generated.

Examples of the present invention will be described below. In the example described below, a bearing that floats and sucks against a flat guide surface (corresponding to the second member 14 in the above-described embodiment) (corresponding to the first member 12 in the above-described embodiment). This is an example in which the present invention is applied. FIG. 1 is a longitudinal sectional view of the bearing of this embodiment, and FIG. 2 is a sectional view taken along the line II-II in FIG. As shown in FIGS. 1 and 2, the bearing 30 of this embodiment includes a lower plate 32 and an upper plate 48.
The lower plate 32 is a disk-shaped thin plate, and the lower surface thereof serves as a bearing surface 32a. For the lower plate 32, for example, an aluminum thin plate can be used. This is because the aluminum thin plate is excellent in workability and can be reduced in weight, and the bearing surface 32a can be efficiently and forcibly displaced. The bearing surface 32a of the lower plate 32 preferably has high flatness. For this reason, after the bearing 30 is assembled, the bearing surface 32a may be subjected to diamond cutting or the like to increase its flatness.

  Three ring plates 42, 44 and 46 are fixed concentrically on the upper surface of the lower plate 32. The ring plates 42, 44, 46 are arranged in order to suppress variation in the forced displacement in the circumferential direction applied to the bearing surface 32 a of the lower plate 32 (that is, arranged to vibrate uniformly in the circumferential direction). . The three ring plates 42, 44, 46 can also be made of thin aluminum plates and can be integrated with the lower plate 32.

Piezoelectric elements 34 are arranged on the ring plate 42 at intervals of 60 ° in the circumferential direction, piezoelectric elements 36 are arranged on the ring plate 44 at intervals of 60 ° in the circumferential direction, and 60 on the ring plate 46 in the circumferential direction. Piezoelectric elements 38 are arranged at intervals of 0 ° (however, only some piezoelectric elements are numbered in the figure). Accordingly, 18 piezoelectric elements 34, 36, 38 are arranged on the upper surface of the lower plate 32, and these piezoelectric elements 34, 36, 38 are arranged radially on the upper surface of the lower plate 32.
As the piezoelectric elements 34, 36, and 38, stacked piezoelectric elements can be used. As the multilayer piezoelectric element, for example, TOKIN (AE1010D16) can be used. When a voltage is applied to the piezoelectric elements 34, 36, 38, the piezoelectric elements 34, 36, 38 press the lower plate 32 through the ring plates 42, 44, 46. When a compressive force acts on the lower plate 32 from the ring plates 42, 44, 46, each part of the lower plate 32 is deformed according to the compressive force.

An upper plate 48 is attached to the upper ends of the piezoelectric elements 34, 36 and 38. The upper plate 48 is also a disk-shaped member, and is more rigid than the lower plate 32. Thereby, even if the compressive force of the piezoelectric elements 34, 36, and 38 acts on the upper plate 48, the upper plate 48 is hardly deformed, and the lower plate 32 can be efficiently deformed. As the upper plate 48, for example, a steel plate (SUS304) can be used.
The central portion of the upper plate 48 and the central portion of the lower plate 32 are fixed with screws 40. As a result, the central portion of the lower plate 32 becomes difficult to vibrate, and the traveling wave generated on the bearing surface 32a is absorbed by the central portion.

In the bearing 30 described above, phase advance vibration (sin (θ + α)) is generated in the piezoelectric element 38 on the outer peripheral side, phase zero vibration (sin θ) is generated in the central piezoelectric element 36, and phase is generated in the inner piezoelectric element 34. When delayed vibration (sin (θ−α)) is generated, a traveling wave is generated from the outer periphery of the bearing surface 32a toward the center. When a traveling wave from the outer periphery of the bearing surface 32a toward the center is generated, a levitation force is generated between the guide surface and the bearing surface 32a, and the bearing 30 is levitated from the guide surface. Therefore, the frictional force acting between the guide surface and the bearing surface 32a can be made extremely small.
On the other hand, phase-delayed vibration (sin (θ−α)) is generated in the piezoelectric element 38 on the outer peripheral side, phase zero vibration (sin θ) is generated in the central piezoelectric element 36, and phase advance vibration ( When sin (θ + α) is generated, a traveling wave is generated from the center of the bearing surface 32a toward the outer periphery. When a traveling wave from the center of the bearing surface 32a toward the outer periphery is generated, an adsorption force is generated between the guide surface and the bearing surface 32a, and the bearing 30 is adsorbed on the guide surface. Therefore, the frictional force acting between the guide surface and the bearing surface 32a can be increased.

In the bearing 30 shown in FIGS. 1 and 2, a laminated piezoelectric element is used. However, any actuator such as a magnetostrictive element instead of the laminated piezoelectric element can generate a traveling wave on the surface of the bearing surface. That's fine. 3 and 4, ring-shaped plate-shaped piezoelectric elements 54, 56, and 58 are bonded to the upper surface of a disk-shaped plate member 52 (for example, an aluminum thin plate). By using the plate-like piezoelectric elements 54, 56, and 58, the upper plate 48 used in the bearing 30 of the above-described embodiment can be eliminated, and a simpler configuration can be achieved.
In addition, the protrusion part 53 is formed in the center of the board member 52, and the upper surface of the protrusion part 53 can be utilized as a table surface on which a workpiece | work etc. are mounted. 3 and 4, the piezoelectric plate is separated into three ring shapes having different diameters and bonded to the plate member 52. However, one ring-shaped piezoelectric plate is bonded to the plate member 52 and the upper surface thereof is bonded. It is good also as a structure which isolate | separates the electrode formed in 3 to 3 ring shape from which a diameter differs.

Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.
For example, in the above-described embodiment, the traveling wave is generated by forcibly vibrating the bearing surface. However, as a method of generating the traveling wave, the traveling wave may be generated using a bolted Langevin type vibrator. . Further, in the above-described example, the gravity balance type configuration is shown as the planar bearing surface and the guide surface. However, the configuration can be a facing type configuration that is supported by the planar bearing from both the upper and lower sides or the left and right sides, or It can be a radial bearing that supports a rotating body as a cylindrical bearing surface, or a spherical bearing that supports a rotating body as a spherical bearing surface, and it is as diverse as conventional bearing devices such as hydrostatic bearings. Can be used for various configurations.
The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in the present specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

It is a longitudinal cross-sectional view of the bearing of a present Example. It is the II-II sectional view taken on the line of FIG. It is a top view of the bearing which concerns on the modification of a present Example. It is the IV-IV sectional view taken on the line of FIG. It is a schematic diagram for demonstrating the principle of the levitation | floating / adsorption force generator of this invention. It is a schematic diagram for demonstrating the method for generating a traveling wave.

Explanation of symbols

10: Levitation / adsorption force generator 12: First member 14: Second members 18a, 18b: Actuator 32: Lower plates 34, 36, 38: Piezoelectric element 40: Upper plates 42, 44, 46: Ring plates

Claims (6)

A first member;
A second member facing the first member;
An actuator provided on at least one of the first member and the second member and generating a traveling wave on the surface of the other member with respect to the one member;
Traveling waves in the direction of supplying fluid between the first member and the second member from the outside to the surface of the other member with respect to one member by the actuator , or the first member and the second member Levitation force or adsorption force is generated between the first member and the second member by generating a traveling wave in the direction of discharging the fluid to the outside from between the first member and the second member Generator.   Generating a levitation force between the first member and the second member by generating a traveling wave from the outside toward the inside on the surface of at least one of the first member and the second member; The levitation / adsorption force generator according to claim 1, wherein   The levitation / adsorption force generating apparatus according to claim 2, wherein traveling waves generated by the actuator are absorbed in a central portion of the first member and the second member.   The second member is supported in a non-contact manner with respect to the first member by a levitation force generated between the first member and the second member. Levitation and adsorption force generator.   Generating an attractive force between the first member and the second member by generating a traveling wave from the inside to the outside on the surface of at least one of the first member and the second member. The levitation / adsorption force generator according to claim 1, wherein A traveling wave in the direction of supplying fluid between the first member and the second member from the outside on the surface of the second member with respect to the first member, or the first member and the second member Levitation force or adsorption force is generated between the first member and the second member by generating a traveling wave in the direction of discharging the fluid to the outside from between the first member and the second member How it occurs.

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