JP3023677B1 - Spherical bearing - Google Patents

Abstract

To provide a spherical bearing capable of performing position adjustment with three degrees of freedom with high accuracy and high rigidity. SOLUTION: Piezoelectric actuators 30 are evenly arranged at least at four or more positions of a housing 17. The applied voltage of the voltage supply unit 39 is adjusted by a not-shown volume so that a preload is evenly applied between the antifriction material 33 and the sphere 1. The preload is applied evenly in order to maintain appropriate rigidity. The material of the anti-friction material 33 is selected so that it is easy to wear and the friction is small as compared with the spherical body 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a spherical bearing,
In particular, the present invention relates to a spherical bearing capable of performing position adjustment with three degrees of freedom with high accuracy and high rigidity.

[0002]

2. Description of the Related Art FIG. 11 shows an example of a three-degree-of-freedom spherical bearing using a rolling couple. In FIG. 11, a connecting shaft 3 is fixed or integrally formed at the lower end of the sphere 1. The sphere 1 has a housing upper part 5A and a housing lower part 5B.
Are housed in the sphere housing part 7 formed by.

[0003] An opening 9 is provided in a part above the spherical body accommodating portion 7.
B, and an opening 9A is provided in a part below.
The housing upper part 5A and the housing lower part 5B
1 is fastened. The sphere 1 is placed in the sphere housing 7.
And a plurality of balls 13 are arranged so as to be in contact with. The ball 13 is supported by a retainer 15.

[0004]

In a conventional three-degree-of-freedom spherical bearing using a pair of rolling bearings, the required accuracy of each component constituting the spherical bearing is high, the manufacturing process is complicated, and production on an automatic line is realized. It was difficult to do. The cost was also high.

In addition, the accuracy and rigidity of the sphere 1, the ball 13, and the sphere housing 7 are rapidly reduced due to wear and the like, so that the positioning accuracy and the load-bearing capacity are rapidly reduced, and there is a possibility that the repair cannot be performed.

Further, the ball 13 may protrude from the trajectory (a circle connecting the centers of the balls 13 together). At this time, the contact area between the ball 13 and the sphere 1 or between the ball 13 and the sphere housing 7 is reduced. Change. Also, the stiffness varies.

Further, the protruding ball 13 has an impact when returning to the trajectory, and there is a possibility that the ball 13 cannot be smoothly swung. The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a spherical bearing capable of performing position adjustment with three degrees of freedom with high accuracy and high rigidity.

[0008]

According to the present invention, there is provided a sphere, a connecting shaft connected to the sphere, and a predetermined portion opened so that the connecting shaft can rotate by a predetermined angle. , A piezoelectric actuator mounted at a plurality of locations of the housing such that the direction of expansion and contraction of the piezoelectric element is directed toward the sphere and / or the center of the housing, and a voltage for expanding and contracting the piezoelectric element of the piezoelectric actuator. Voltage adjusting means for adjusting the voltage, a voltage supplying means for supplying a voltage to the piezoelectric element based on the adjustment result of the voltage adjusting means, and a piezoelectric element fixed to the tip of the piezoelectric element of the piezoelectric actuator, and the piezoelectric element is An anti-friction material that slides while being pressed against the surface of the sphere when extended, and connecting means provided at a predetermined position of the housing so as to be connected to other members. It was constructed Te.

The piezoelectric actuator is mounted at a plurality of locations on the housing such that the direction of expansion and contraction of the piezoelectric element is directed toward the sphere and / or the center of the housing. Attaching the piezoelectric element so that the direction of expansion and contraction of the piezoelectric element is directed toward the center of the sphere facilitates uniform preload. The voltage adjusting means adjusts a voltage for expanding and contracting the piezoelectric element of the piezoelectric actuator.

[0010] The pressure between the surface of the sphere and the piezoelectric element can be adjusted by the magnitude of the voltage applied to the piezoelectric actuator, thereby facilitating uniform preloading, obtaining optimal rigidity, and optimal rigidity in any situation. Can be controlled. An antifriction material is fixed to the tip of the piezoelectric element of the piezoelectric actuator. This antifriction material slides while pressing the spherical surface when the piezoelectric element is extended.

As described above, smooth swinging with three degrees of freedom having high accuracy and high rigidity is possible. Further, the contact area between the sphere and the anti-friction material is kept substantially constant, the frictional resistance between them is reduced, and a smooth swing can be obtained.

[0012] Even if the antifriction material is worn, it is possible to return the accuracy and rigidity by adjusting the voltage of the voltage adjusting means. Therefore, the service life can be extended. Further, it is easy to realize the processing accuracy and the assembly accuracy of each part, the productivity in the automatic line is good, and the cost reduction can be expected.

By printing a conductor connecting the voltage supply means and the piezoelectric actuator on the surface of the housing, cables can be eliminated. Also, when the piezoelectric actuators are evenly arranged at a plurality of locations on the housing,
It is desirable because rigidity can be maintained in a well-balanced manner.

Further, according to the present invention, the piezoelectric actuator comprises: a piezoelectric element supporting portion for supporting one end of the piezoelectric element;
An extension extending from the piezoelectric element support toward the tip of the piezoelectric element at a predetermined distance from the piezoelectric element along the piezoelectric element, and a piezoelectric element distortion limit protruding from an inner periphery of the extension. And a part.

The piezoelectric element support supports one end of the piezoelectric element. A part of the piezoelectric element support is extended from the piezoelectric element support. However, the extension may be fixed to the piezoelectric element support as a component independent of the piezoelectric element support. The extension portion extends toward the distal end of the piezoelectric element while keeping a predetermined distance from the piezoelectric element along the piezoelectric element. Then, a piezoelectric element distortion limiting portion is protruded from the inner periphery of the extension portion.

The sphere rotates with the movement of the connecting shaft.
Since the piezoelectric element is pressed against the sphere at a predetermined pressure, the piezoelectric element tends to move in the circumferential direction of the sphere as the sphere rotates. Since the piezoelectric element is fragile to pressure in a direction perpendicular to the direction of expansion and contraction, displacement in this direction is limited by the piezoelectric element distortion limiter. Thus, the life of the piezoelectric element can be prolonged.

Further, according to the present invention, in the piezoelectric actuator, the piezoelectric element is inserted into a through hole penetrating the housing, and a predetermined distance is provided between a piezoelectric element supporting portion for supporting one end of the piezoelectric element and an outer periphery of the housing. Characterized by being fixed to the housing via an adjusting ring having a thickness of.

By disposing the adjusting ring, it is possible to eliminate an assembly error of the spherical bearing. In addition, a bellows-like protective cover that covers the gap between the opening of the housing and the connecting shaft may be provided to prevent dust and prevent moisture.

Further, the present invention further comprises a reaction force detecting means for detecting a reaction force accompanying expansion and contraction of the piezoelectric element, and the voltage adjusting means comprises a piezoelectric element based on the reaction force detected by the reaction force detection means. The voltage for expanding and contracting the element is adjusted.

The reaction force detecting means may estimate the magnitude of the reaction force from the amount of electricity returned to the piezoelectric element due to the reaction force,
It may be detected by a pressure sensor provided separately. The voltage adjusting means adjusts a voltage for expanding and contracting the piezoelectric element based on the reaction force detected by the reaction force detecting means. As described above, the preload on the sphere of the piezoelectric element is always kept constant.

The surface of the antifriction material facing the sphere can be formed in a concave shape or a convex shape. Also,
The ball that is rotatable while contacting the sphere may be held by the ball holding unit. By doing so, the wear of the antifriction material can be reduced or the friction can be reduced.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a longitudinal sectional view of the first embodiment of the present invention. FIG. 2 is a partially enlarged view of the first embodiment of the present invention. The same elements as those in FIG. 11 are denoted by the same reference numerals, and description thereof is omitted.

In FIG. 1, the sphere 1 has a housing 17
Is housed inside. The lower end of the connecting shaft 3 is
Is combined with An opening 18 is provided at a lower portion of the housing 17 so that the connecting shaft 3 can rotate by a predetermined angle.

On the upper part of the housing 17, a connecting shaft 23 is provided.
Are formed integrally with the housing 17. Connecting shaft 23
Is coupled to the base 21. A plurality of through holes 25 having screw grooves formed in the inner peripheral surface thereof are provided at a plurality of positions at an equal angle α from the center O of the housing 17.

In FIG. 2, a flat surface 31 is provided around the through hole 25 on the outer surface of the housing 17. The flat surface 31 is disposed so as to be parallel to a contact surface virtually drawn at a point that intersects the center of the through hole 25 on the outer surface of the housing 17.

The piezoelectric actuator 30 is mounted on the housing 1
7, a piezoelectric element 30a is inserted into the through hole 25 from the outside, and the piezoelectric element supporting portion 30b is screwed and fixed in the through hole 25. However, the piezoelectric element support 30b may be fixed to the flat surface 31 with screws. The center O of the sphere 1 is disposed so as to coincide with the center of the housing 17.

The center line of the piezoelectric element 30a is arranged so as to pass through the center O of the sphere 1. The arrangement of the housing 17, the sphere 1, the piezoelectric actuator 30, and the like have a symmetric structure with respect to the orthogonal planes XOZ and YOZ. An anti-friction material 33 is fixed to the tip of the piezoelectric element 30a.

A connector 35 for the piezoelectric element 30a is embedded in the piezoelectric element support 30b. The connector 35 is connected to a voltage supply unit 39 via a cable 37. The voltage supply unit 39 corresponds to a voltage supply unit. The adjustment of the voltage to the voltage supply unit 39 is performed by a volume not shown. This volume corresponds to voltage adjusting means.

Next, the operation of the first embodiment of the present invention will be described. It is desirable that the piezoelectric actuators 30 are evenly arranged at least at four or more locations on the housing 17. However, even if they are not evenly arranged, if the shape of the housing 17 as shown in FIG. 3 is a polyhedron, if the center line of the piezoelectric element 30a passes through the center O of the sphere 1, The position of the sphere 1 can be adjusted sufficiently.

The voltage applied to the voltage supply unit 39 is adjusted by the volume so that the preload is evenly applied between the antifriction material 33 and the sphere 1. The preload is applied evenly in order to maintain appropriate rigidity. The material of the anti-friction material 33 is selected so that it is easy to wear and the friction is small as compared with the spherical body 1. Sphere 1
When cast iron is used, the material of the anti-friction material 33 is, for example, bronze, mild steel, cast iron, or the like.

The connecting shaft 23 may be screwed to the housing 17. Also, by printing a conductor on the surface of the housing 17 and replacing the conductor with the cable 37,
Cables can be eliminated.

As a result, a smooth swing with three degrees of freedom having high precision and high rigidity is possible. Even if the anti-friction material 33 is worn, the accuracy and rigidity can be restored by adjusting the voltage of the voltage supply unit 39.

Therefore, the service life can be extended. In addition,
When the piezoelectric element support 30b is screwed to the flat surface 31 of the housing 17, replacement and maintenance of the piezoelectric actuator 30 are easy.

Next, a second embodiment of the present invention will be described. FIG. 4 shows a longitudinal sectional view of the second embodiment of the present invention. The same elements as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 4, the opening 1 of the housing 17 is shown.
A bellows-like protective cover 41 is provided in the gap between the peripheral edge 8 and the connecting shaft 3.
Is attached. This can prevent dust and moisture from entering the housing 17 through the opening 18.

Next, a third embodiment of the present invention will be described. FIG. 5 shows a partially enlarged view of the third embodiment of the present invention. The same elements as those in FIG. 2 are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 5, an adjusting ring 43 having a predetermined thickness is interposed between the piezoelectric element supporting portion 30b and the flat surface 31 of the housing 17. This adjustment ring 4
By disposing 3, the assembly error of the spherical bearing can be eliminated. Further, by adjusting the thickness of the adjusting ring 43, the wear of the antifriction material 33 can be supplemented.

Next, a fourth embodiment of the present invention will be described. FIG. 6 shows a partially enlarged view of the fourth embodiment of the present invention. Note that the same components as those in FIG. 5 are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 6, while extending a part of the piezoelectric element supporting portion 30b along the piezoelectric element 30a at a predetermined distance from the piezoelectric element 30a, a cylindrical extension 45 is provided toward the tip of the piezoelectric element 30a. I do.

A projecting portion 47 is provided on the inner periphery of the extension portion 45. The protruding portion 47 corresponds to a piezoelectric element distortion limiting portion. Accordingly, the displacement of the piezoelectric element 30a in the direction perpendicular to the expansion and contraction direction is limited, and the life of the piezoelectric element 30a can be extended.

Next, a fifth embodiment of the present invention will be described. The fifth embodiment of the present invention relates to a configuration example of an anti-friction material. FIG. 7 shows a configuration diagram of an antifriction material. In FIG. 7, the surface 49 facing the sphere 1 is formed in a concave shape along the shape of the sphere 1.

As a result, uniform wear is expected in the concave shape, and the rigidity after the wear can be easily adjusted. Also,
The rigidity of the sphere 1 can be evenly applied without bias.

Next, a sixth embodiment of the present invention will be described. The sixth embodiment of the present invention relates to another configuration example of the antifriction material. FIG. 8 shows another configuration diagram of the antifriction material.

In FIG. 8, the surface 51 facing the sphere 1 is
It is formed in a convex shape. As a result, the area in contact with the sphere 1 is minimized, and the friction is small.

Next, a seventh embodiment of the present invention will be described. The seventh embodiment of the present invention relates to another configuration example of the antifriction material. FIG. 9 shows another configuration diagram of the antifriction material.

In FIG. 9, a ball 53 rotatable while being in contact with the sphere 1 is held by a ball holding portion 55. As a result, the area in contact with the sphere 1 is minimized, and the friction is small. Also, wear is very low.

Next, an eighth embodiment of the present invention will be described. FIG. 10 shows a partially enlarged view of the eighth embodiment of the present invention. Note that the same components as those in FIG. 5 are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 10, a pressure sensor 57 is disposed at an end of the piezoelectric element 30a inside the piezoelectric element support 30b. This pressure sensor 57 detects the magnitude of the reaction force from the sphere 1 accompanying the expansion and contraction of the piezoelectric element 30a.

The output signal of the pressure sensor 57 is input to a voltage regulator (not shown), and the difference between the output signal and a preset pressure is calculated. Then, the magnitude of the voltage applied to the piezoelectric element 30a is adjusted based on the magnitude of the difference. The adjusted voltage is output from the voltage supply unit 39.

Note that, without using the pressure sensor 57, the magnitude of the reaction force may be estimated from the amount of electricity returned to the piezoelectric element 30a due to the reaction force. The magnitude of the electric quantity is determined by, for example, connecting a resistor in series with the piezoelectric element 30a and measuring the magnitude of a current flowing through the resistor. The magnitude of this current is input to a voltage regulator (not shown), and the magnitude of the reaction force is estimated.

Then, the magnitude of the estimated reaction force is compared with a preset pressure, and the magnitude of the voltage applied to the piezoelectric element 30a is adjusted based on the magnitude of the difference.
The adjusted voltage is output from the voltage supply unit 39. As described above, the preload of the piezoelectric element 30a to the sphere 1 is always kept constant.

[0052]

As described above, according to the present invention, the lubricating material can be pressed against the spherical surface by expanding and contracting the piezoelectric element of the piezoelectric actuator. The swing of the degree of freedom is possible.

[0053]

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a first embodiment of the present invention.

FIG. 2 is a partially enlarged view of the first embodiment of the present invention.

FIG. 3 shows another example of a housing configuration.

FIG. 4 is a longitudinal sectional view of a second embodiment of the present invention.

FIG. 5 is a partially enlarged view of a third embodiment of the present invention.

FIG. 6 is a partially enlarged view of a fourth embodiment of the present invention.

FIG. 7 is a configuration diagram of an antifriction material.

FIG. 8 is a diagram showing another configuration of the antifriction material.

FIG. 9 is a diagram showing another configuration of the antifriction material.

FIG. 10 is a partially enlarged view of an eighth embodiment of the present invention.

FIG. 11 is a diagram showing an example of a three-degree-of-freedom spherical bearing formed by a rolling couple;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sphere 3, 23 Connecting shaft 17 Housing 18 Opening 25 Through-hole 30 Piezoelectric actuator 30a Piezoelectric element 30b Piezoelectric element support part 31 Flat surface 33 Lubricant 39 Voltage supply part 41 Protective cover 43 Adjusting ring 45 Extension part 47 Protrusion Part 49 Concave surface 51 Convex surface 53 Ball 55 Ball holding part 57 Pressure sensor

Claims (10)

(57) [Claims] A sphere, a connecting shaft connected to the sphere, a housing having a predetermined portion opened so that the connecting shaft can rotate by a predetermined angle, and a housing accommodating the sphere therein;
A piezoelectric actuator attached to a plurality of portions of the housing such that the direction of expansion and contraction of the piezoelectric element is directed toward the sphere and / or the center of the housing; voltage adjusting means for adjusting a voltage for expanding and contracting the piezoelectric element of the piezoelectric actuator;
A voltage supply unit for supplying a voltage to the piezoelectric element based on an adjustment result of the voltage adjustment unit; and a voltage fixing unit fixed to a tip of the piezoelectric element of the piezoelectric actuator, and when the piezoelectric element is extended by the voltage adjustment unit, the surface of the sphere is deformed. A spherical bearing, comprising: an anti-friction material that slides while being pressed, and connecting means provided at a predetermined position of the housing so as to be connected to another member. 2. The spherical bearing according to claim 1, wherein a conductive wire connecting the voltage supply means and the piezoelectric actuator is printed on a surface of the housing. 3. The piezoelectric actuator according to claim 1, further comprising: a piezoelectric element support for supporting one end of the piezoelectric element; and a tip end direction of the piezoelectric element spaced apart from the piezoelectric element by a predetermined distance along the piezoelectric element from the piezoelectric element support. An extension that is extended toward
3. The spherical bearing according to claim 1, further comprising a piezoelectric element distortion limiting portion protruding from an inner periphery of the extension portion. 4. The piezoelectric actuator according to claim 1, wherein the piezoelectric element is inserted into a through hole penetrating the housing, and has a predetermined thickness between a piezoelectric element supporting portion supporting one end of the piezoelectric element and an outer periphery of the housing. 4. The spherical bearing according to claim 1, wherein the spherical bearing is fixed to the housing via an adjusting ring. 5. The spherical bearing according to claim 1, further comprising a bellows-like protective cover for covering a gap between the opening of the housing and the connecting shaft. 6. The apparatus according to claim 1, further comprising a reaction force detecting means for detecting a reaction force accompanying expansion and contraction of the piezoelectric element, wherein the voltage adjusting means expands and contracts the piezoelectric element based on the reaction force detected by the reaction force detection means. 4. The method of claim 1, wherein the voltage is adjusted.
The spherical bearing according to 4 or 5. 7. The method according to claim 1, wherein a surface of the friction reducing material facing the sphere is formed in a concave shape along the surface shape of the sphere. Spherical bearing. 8. A surface of the antifriction material facing the sphere is formed in a convex shape.
A spherical bearing according to 4, 5, 6, or 7. 9. A ball which is rotatable while being pressed against said sphere instead of said friction reducing material, and a ball holding portion for holding said ball, wherein said ball holding portion is a piezoelectric element of said piezoelectric actuator. 9. The spherical bearing according to claim 1, wherein the spherical bearing is fixed to a tip of the spherical bearing. 10. The spherical bearing according to claim 1, wherein the piezoelectric actuators are evenly arranged at a plurality of positions on the housing. .