JP3228610B2 - Ultrasonic actuator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic actuator.

[0002]

2. Description of the Related Art The present inventors have previously described Japanese Patent Application No. 4-321.
No. 096 proposes an ultrasonic linear actuator capable of generating a translational motion. The configuration and principle will be described with reference to the drawings. FIG. 14 is a front view showing the configuration of the ultrasonic vibrator 10, in which three holding elastic bodies 12 are fixed on the upper surface of a basic elastic body 11, and a laminated piezoelectric body 13 is placed between the holding elastic bodies 12. It is the one that is clamped and fixed. The basic elastic body 11 is formed by processing a brass material into a rectangular parallelepiped shape, and the holding elastic body 12 is epoxy-bonded to a total of three places (a part corresponding to a secondary bending vibration node) at both ends and a center part of the upper surface. It is fixed with an agent and is further screwed down. The laminated piezoelectric members 13 are held between the respective elastic members 12 for holding. Further, a resin coating is applied to a side surface of the laminated piezoelectric body 13. Further, sliding members 15 are bonded to both ends of the bottom surface of the basic elastic body 11.

When a sinusoidal voltage is applied to the laminated piezoelectric body 13, two kinds of vibrations are simultaneously excited in the basic elastic body 11, and displacements of these two kinds of vibrations are synthesized, so that the sliding member 15 has an elliptical locus. Vibrates along. Therefore, when a driven body (not shown) is pressed against the sliding member 15, the driven body receives a driving force from the vibration of the elliptical trajectory and performs a translational movement.

FIGS. 15 and 16 are perspective views for explaining the two kinds of vibrations excited by the basic elastic body 11, and FIG. 15 shows a simple stretching vibration. FIG.
Indicates a transverse elastic wave propagating in the direction of the expansion and contraction, and is a secondary standing wave. The length and width of the basic elastic body 11 are set so that the primary resonance frequency of the stretching motion and the frequency of the secondary standing wave of the transverse wave match. Therefore, the laminated piezoelectric body 1 shown in FIG.
By simply giving the vibration of the frequency by 3, the two kinds of resonances are simultaneously excited in the basic elastic body 11. At the position of the antinode of the vibration of the secondary standing wave, displacements of the two kinds of vibrations are synthesized, and the mass point vibrates along an elliptical locus. Therefore, when the sliding member 15 is provided at that position and the driven body is pressed against the sliding member 15, the driven body moves in translation under the action of the elliptical vibration.

FIG. 17 is a front view showing the entire structure of an ultrasonic linear actuator using the ultrasonic transducer 10. The ultrasonic transducer 10 is self-propelled on rails 21 left and right. , Rails 21 to guide this
The linear guide moving part 23 is provided on the lower end of the support mechanism of the ultrasonic vibrator 10 while the linear guide fixing part 22 is
Is provided. The ultrasonic transducer 10 is supported by the support member 24 at the position of the node of the secondary standing wave. The support member 24 has a U-shape, and a connecting rod 25 is connected thereto. A spring receiver 26 is provided at the upper end of the connecting rod 25.
Are formed. On the other hand, a linear guide fixing portion 22 is integrally fixed to the back surface of the rail 21. A frame 30 is fixed to the linear guide moving portion 23, and an upper frame 31
And one with. A tap is cut in the center of the upper frame 31, and a bolt 29 is screwed therein. A spring retainer 28 is attached to the bolt 29 to adjust the length of the spring 27 so that the contact pressure between the ultrasonic vibrator 10 and the rail 21 can be adjusted.

The sliding surface of the ultrasonic linear actuator having such a structure is subjected to a dynamic load of impact and a frictional force, and is subjected to extremely severe use conditions. Therefore, the suitability of the properties of the sliding material used for the sliding portion is the key to determining the characteristics and life of the ultrasonic actuator.

Conventionally, as a sliding material, S
There is US440C in which zirconia is used for a driven body (rail 21).

[0008]

However, in the above-mentioned combination of the sliding materials, as a result of the durability test, the driving force becomes uneven and the driven body does not move at a uniform speed. Sometimes the parts bite and stop. 10
A reddish-brown transfer film was irregularly adhered to the surface of the driven body after performing the sliding operation for every 10,000 rounds, and the surface was uneven.
In addition, countless striations were formed on the surface of the sliding member 15, indicating that it was severely worn.

Further, in order to know the phenomena occurring on these surfaces, the surfaces were observed with a scanning electron microscope. 18 and 19 show scanning electron microscope images of the surface of the sliding member 15, and FIGS. 20 to 24 show scanning electron microscope images of the surface of the driven body. FIG.
In 8, the surface of the sliding member 15 of SUS440C is rich in irregular irregularities, and a lot of abrasion powder is placed thereon.
It is unlikely that these irregularities are traces that have been neatly scraped off by the mating material, and it is thought that the surface texture has been worn away so that the surface texture is peeled off, but this is different from the original behavior of iron itself. FIG. 19 is a partially enlarged view of FIG. 18 and shows that the strips are separated so as to be peeled off from the surface and become wear powder.

On the other hand, as shown in FIG. 20, a transfer film is seen on the surface of the zirconia driven body, which is a deposit that was macroscopically viewed as reddish brown. FIG. 21 is a partially enlarged view of FIG. The transfer film is visible in the upper half in FIG. 20, and it can be seen that the scale-like small pieces are deposited innumerably to form the transfer film. FIGS. 22 to 24 show the results of elemental analysis of the transfer film. FIG.
FIG. 24 shows the result of mapping using secondary X-rays of Zr. 22 and FIG. 23, and FIG. 22 and FIG. 24, it can be seen that the transfer film in FIG. 22 is iron.

As described above, in the conventional sliding material, the surface of the sliding member 15 is oxidized to iron oxide, which is peeled off to form abrasion powder, and a part of it is deposited on the surface of the driven body. It turns out that it becomes a transfer film. The transfer film grows irregularly along with the sliding, causing an obstacle to the sliding, causing a driving force to become uneven, and causing the sliding portion to bite and stop.

That is, the sliding material used for the sliding portion of the conventional ultrasonic actuator has a property that a transfer film is formed upon sliding, and this deposits on the sliding surface. In many cases, the transfer film adheres to an irregular shape and has a physical property different from that of the original sliding material, which causes uneven driving force and biting. That is, the conventional ultrasonic actuator has a problem that stable operation and driving force cannot be obtained due to the sliding material.

The present invention has been made in view of such a conventional problem, and provides an ultrasonic actuator which slides while preventing deposition of a transfer film from occurring, and does not cause uneven driving force or biting. The purpose is to:

[0014]

According to a first aspect of the present invention , there is provided an electro-mechanical energy conversion device comprising an elastic body and an electro-mechanical energy conversion element fixed to the elastic body. By applying an alternating current to the element,
A vibrator for generating vibration on the surface of the elastic body, a driven body relatively moved with respect to the vibrator by being pressed against the surface of the elastic body, and a resin having abrasive grains.
The sliding provided on the pressure contact surface of the vibrator with the driven body
And the driven body is formed of zirconia.
It is characterized by having been done . Invention of claim 2, claim
2. The ultrasonic actuator according to claim 1, wherein:
The mechanical energy conversion element is a laminated piezoelectric element.
Features. According to a third aspect of the present invention, there is provided an elastic body,
An electro-mechanical energy conversion element fixed to the
Applying alternating current to the electromechanical energy conversion element
A vibrator for generating vibration on the surface of the elastic body
And the vibration caused by being pressed against the surface of the elastic body.
A driven body that moves relatively to the child,
By being pressed against the surface, relative to the vibrator
Consisting of a driven body that moves to and a resin having abrasive grains,
At least one of pressure contact surfaces between the vibrator and the driven body
And a sliding member provided on the surface of the vibrator.
Equipped with at least two stacked piezoelectric elements as a power source
In addition, the basic elastic body as the elastic body and the basic elastic body
And holding elastic bodies joined together,
The two ends of the laminated piezoelectric element project from the holding elastic body.
It is characterized by being held by contact.

[0015]

In the ultrasonic actuator having the above-described structure, even if a transfer film is generated on the sliding surface, the abrasive grains slide while constantly shaving off the abrasive, so that the fresh surfaces always come into contact with each other. And the sliding conditions are stable.

In the present invention, the friction and wear phenomena occurring in the sliding portion of the ultrasonic actuator are investigated, the conditions of the sliding material are selected, and the more stable mode of the wear phenomenon appears. I decided to control it. According to the knowledge obtained in the process of completing the invention, as shown in FIG. 2, in the material of the sliding portion, fine strips 1 are constantly falling and reattaching on the surface thereof. Some of the strips 1 that have fallen off are separated without reattaching to the sliding surface, but some of them are also fixed to the surface of the driven body 2 to form the transfer film 3, and the rest is abrasion powder. Become. Therefore, in order to stabilize the operation of the ultrasonic actuator, the transfer film 3 may be prevented from being generated. However, as shown in FIG. 3, it is unnatural and impossible to collect all of the strips 1 that have fallen off at the sliding portion and slide while reattaching to the sliding portion. is there. Further, as shown in FIG. 4, the transfer film 3 which has once adhered to a wide area cannot be scraped and slid while re-adhering to a sliding portion in a narrow area.

In view of the above, the present invention has changed the idea, and as shown in FIG. 1, at least one of the sliding materials contains abrasive grains so as to have abrasiveness. In this way, even if the transfer film 3 adheres to the sliding surface, it is scraped off with sliding, the sliding material itself is slightly scraped, and the new surface always slides. Here, there is a concern that abrasion powder will increase. However, if the hardness of the abrasive grains is set to be equal to or slightly higher than the hardness of the counterpart material, the amount of scraping of the sliding material itself is microscopic. And no macroscopic dusting occurs.

[0018]

EXAMPLE (Structure) A commercially available dresser board was cut and used as the sliding member 15 of the ultrasonic actuator shown in FIG. 17, and the driven body (rail 21) was kept zirconia. This dresser board is used for dressing a grindstone containing diamond abrasive grains, and is made by connecting abrasive grains having hardness slightly lower than that of diamond with a resin.

(Action) When a durability test was performed using the ultrasonic actuator of this embodiment, the operation was extremely stable, and there was no unevenness or biting of the driving force. After 100,000 reciprocations, the surface of the driven body was pure white equivalent to that in the initial state, and although slight sliding marks were observed, there was no adhesion and almost no wear powder was visually observed. Further, the sliding member 15
There was no particular change on the surface and no evidence of wear.

FIGS. 5 to 7 show scanning electron microscope images of the surface of the sliding member 15 before sliding in this embodiment. As shown in FIG. 5, the sliding member 15 of the dresser board contains a large amount of abrasive grains. FIG. 6 is a partially enlarged view of FIG.
FIG. 7 shows the result of elemental analysis, which is the result of mapping of Al by secondary X-rays. From the comparison between FIG. 6 and FIG. 7, it is considered that the abrasive is alumina. Alumina has a hardness similar to that of zirconia of the driven body, and thus well matches the intention of the present invention described above.

FIGS. 8 to 11 show scanning electron microscope images of the surface of the sliding member 15 after 100,000 reciprocations in this embodiment. As shown in FIG. 8, a film-like deposit is found at a low contact pressure at the end of the contact portion, and a spot-like bright spot is seen at a high contact pressure. FIGS. 9 and 10 are partially enlarged views in which portions having low surface pressure in FIG. 8 are sequentially enlarged.
It can be seen that the deposit in question is not a film but an accumulation of powder. FIG. 11 is a partially enlarged view of a portion where the surface pressure is high in FIG. 8, but what appears to be a bright point is a small-scale accumulation of powder, and abrasive grains are exposed in other portions. You can see that.

From the above, the resin of zirconia or binder is separated as fine abrasion powder during sliding and is deposited on the surface. However, in a portion where the surface pressure is high, the resin is constantly shaved off and the abrasive grains are exposed. it seems to do. 12 and 13 are scanning electron microscope images of the surface of the driven body of this embodiment after 100,000 reciprocations. Although the surface of zirconia has been shaved, it is apparent that the surface is clearly smoother than the conventional zirconia shown in FIGS.

(Effects) According to the present embodiment, a stable operation can be obtained only by using a commercially available dresser board having good availability as a sliding material without particularly preparing a sliding material. There is. Further, in the present embodiment, the ultrasonic actuator proposed by the present inventors has been described as an example, but the effect of the present invention is not unique to this ultrasonic actuator, and the sliding element accompanied by ultrasonic vibration is used. Is universally applicable. Therefore, the present invention naturally includes application to all types of ultrasonic actuators and other sliding elements with ultrasonic vibration.

[0024]

As described above, according to the ultrasonic actuator of the present invention, extremely stable operation can be achieved without uneven driving force or biting.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a sliding portion for explaining the operation of the present invention.

FIG. 2 is a cross-sectional view showing a sliding portion during operation of the ultrasonic actuator.

FIG. 3 is a cross-sectional view showing a sliding portion during operation of the ultrasonic actuator.

FIG. 4 is a cross-sectional view showing a sliding portion during operation of the ultrasonic actuator.

FIG. 5 is a scanning electron microscope image showing a surface of a sliding member according to an embodiment of the present invention before sliding.

FIG. 6 is a scanning electron microscope image showing a surface of a sliding member according to an embodiment of the present invention before sliding.

FIG. 7 is a scanning electron microscope image showing a surface of a sliding member according to an example of the present invention before sliding.

FIG. 8 is a scanning electron microscope image showing the surface of the sliding member of the example after sliding after 100,000 reciprocations.

FIG. 9 is a scanning electron microscope image showing the surface of the sliding member of Example after sliding after 100,000 reciprocations.

FIG. 10 is a scanning electron microscope image showing the surface of the sliding member of Example after sliding back and forth after 100,000 reciprocations.

FIG. 11 is a scanning electron microscope image showing the surface of the sliding member of Example after sliding back and forth after 100,000 reciprocations.

FIG. 12 is a scanning electron microscope image showing the surface of the driven body of the embodiment after sliding after 100,000 reciprocations.

FIG. 13 is a scanning electron microscope image showing the surface of the driven body of the embodiment after sliding after 100,000 reciprocations.

FIG. 14 is a front view showing an ultrasonic transducer.

15 is a perspective view showing a vibration state of the ultrasonic transducer shown in FIG.

16 is a perspective view showing a vibration state of the ultrasonic transducer shown in FIG.

FIG. 17 is a front view showing an ultrasonic actuator including the ultrasonic transducer shown in FIG.

FIG. 18 is a scanning electron microscope image showing the surface of a conventional sliding member after sliding after 100,000 reciprocations.

FIG. 19 is a scanning electron microscope image showing the surface of the conventional sliding member after sliding after 100,000 reciprocations.

FIG. 20 is a scanning electron microscope image showing a surface of a conventional driven body after sliding after 100,000 reciprocations.

FIG. 21 is a scanning electron microscope image showing the surface of a conventional driven body after sliding after 100,000 reciprocations.

FIG. 22 is a scanning electron microscope image showing the surface of a conventional driven body after sliding after 100,000 reciprocations.

FIG. 23 is a scanning electron microscope image showing the surface of a conventional driven body after sliding after 100,000 reciprocations.

FIG. 24 is a scanning electron microscope image showing a surface of a conventional driven body after sliding after 100,000 reciprocations.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 strip 2 driven body 3 transfer film 10 ultrasonic transducer 11 basic elastic body 12 elastic body for holding 13 laminated piezoelectric body 15 sliding member

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshiharu Tsuhata 2-43-2 Hatagaya, Shibuya-ku, Tokyo Inside the Olympus Optical Industrial Co., Ltd. (72) Takashi Ouchi 2-43-2 Hatagaya, Shibuya-ku, Tokyo No. Olympus Optical Co., Ltd. (56) References JP-A-4-340381 (JP, A) JP-A-3-49573 (JP, A) (58) Fields studied (Int. Cl. ⁷ , DB name) ) H02N 2/00

Claims (3)

(57) [Claims] 1. An elastic body and an electric body fixed to the elastic body.
A vibrator that includes a mechanical energy conversion element and generates an oscillation on the elastic body surface by applying an alternating current to the electro-mechanical energy conversion element; and a vibrator that is pressed against the elastic body surface. A driven body that relatively moves with respect to , and a resin having abrasive grains, and the driven body of the vibrator and
The driven member is formed of zirconia.
An ultrasonic actuator characterized by the above. 2. The electro-mechanical energy conversion element according to claim 1,
2. The multi-layer piezoelectric element according to claim 1, wherein
Ultrasonic actuator. 3. An elastic body and an electric body fixed to the elastic body.
An electric-mechanical energy device comprising a mechanical energy conversion element;
By applying an alternating current to the energy conversion element,
A vibrator that generates vibration on the surface of the body, By being pressed against the elastic body surface,
A driven body that moves relatively to the By being pressed against the elastic body surface,
A driven body that moves relatively to the It is made of a resin having abrasive grains, and the vibrator and the driven body
Sliding part provided on at least one of the press contact surfaces of
With materials, The vibrator has at least two stacked types as a driving source.
It has a piezoelectric element and a basic elastic body as an elastic body.
And a holding elastic body joined to the basic elastic body.
And both ends of each laminated piezoelectric element hold the said
That it is held against the elastic body
Ultrasonic actuator characterized.