JPH08298791A - Vibration wave drive device - Google Patents

Abstract

PURPOSE: To generate oxidation wear with an extremely small wear rate and to extend life by forming both of a first part in contact with at least a contact body of a vibration body and a second part in contact with at lest the vibration body of the contact body with iron or iron alloy and making different their compositions. CONSTITUTION: A wear material 1a as a contact part connected to a vibration body 1 is provided. Namely, it becomes a wear material at a contact body side. On the other hand, a wear material 2a as a contact part connected to a traveling body 2 as the traveling body is provided. Namely, it is a wear material at the traveling body side. No generation of rust is recognized for stainless steel by combining wear materials. Also, stainless steel containing approximately 1-3% molybdenum should be used under more strict environment. Also, When the hardness of the wear materials differs or Al and Si are contained, A12 O3 or SiO2 is generated near the metal surface and they suppress the growth of iron oxide film, thus preventing blue color from being exposed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration wave driving device.

[0002]

2. Description of the Related Art Conventionally, as a friction material of a friction member of an ultrasonic motor as a vibration wave driving device, for example, JP-A-2-
17876 publication. In these examples, stainless steel or carbon steel is used as the material for the vibration body after considering both the characteristics as the vibration body (stator) and the characteristics as the friction material. As a result, the mechanical Q of the vibrating body can be increased and the wear resistance of the vibrating body can be significantly improved.

[0003]

However, in the conventional friction material, the friction material is specified only as the friction material on the vibrator side. It must be said that this is not sufficient as the friction material of the ultrasonic motor driven by the frictional force generated when the surfaces of the two friction materials are always in direct contact with each other.

This has been said for a long time. (For example, the surface engineering published by the first edition in 1976 by Yoshiro Endo, Yokendo, page 63, line 6 says "It changes depending on the partner material to be combined.")
The present inventor confirmed this by an experiment using an ultrasonic motor. In other words, the amount of wear depends on the mating material to be combined,
The form of wear, the wear coefficient, etc. differ significantly.

The same thing can be said not only for the friction material on the side of the vibrating body, but also on the basis of the friction material on the side of the moving body as the contact body which is the counterpart material. Even if the friction material on the side of the vibrating body does not reach the end of its life, if the friction material on the side of the moving body wears out, it means that the life of the ultrasonic motor has ended. That is, as the friction material of the ultrasonic motor, it is necessary to specify two friction materials that are in contact with each other.

As described above, an object of the invention according to the present application is to provide a friction material necessary for producing an oscillatory wave drive device having high wear resistance and excellent startability in an environment that can occur everyday. .

Another object is to address the need to consider use in corrosive environments.

Another object is to generate a more stable frictional force.

[0009]

According to a first aspect of the present invention, there is provided a vibration wave driving device having a vibrating body that generates vibration and a contact body that is in contact with the vibrating body and that moves relative to the vibrating body due to the vibration. In, the first portion of the vibrating body that comes into contact with at least the contact body and the second portion of the contact body that comes into contact with at least the vibrating body are both iron or iron alloy, and they are mutually It is characterized by vibration wave drive devices having different compositions (components).

According to a second aspect of the present invention, there is provided a vibration wave driving device having a vibrating body that generates vibration and a contact body that is in contact with the vibrating body and moves relatively to the vibrating body due to the vibration. First contacting at least the contact body
And a second portion of the contact body that is in contact with at least the vibrating body are both made of iron or an iron alloy, and their surface hardnesses are different from each other.

The invention of claim 3 is characterized by an oscillatory wave drive device using stainless steel as the iron alloy.

A fourth aspect of the present invention is a vibration wave driving device using an iron alloy containing at least 1% by weight of silicon in at least one of the first portion and the second portion.

A fifth aspect of the present invention is a vibration wave driving device using an iron alloy containing at least 0.5% by weight of aluminum in at least one of the first portion and the second portion.

According to a sixth aspect of the present invention, in a vibration wave drive device having a vibrating body that generates vibration and a contact body that is in contact with the vibrating body and moves relatively to the vibrating body due to the vibration, First contacting at least the contact body
And at least one of the second portions of the contact body that come into contact with the vibrating body have a surface hardness of 80 Vickers hardness.
The oscillating wave drive device is characterized by a cermet that is zero or more metals, ceramics, or a composite material thereof, and the other is iron or an iron alloy.

The invention of claim 7 is a vibration wave driving device using stainless steel as the iron alloy.

The invention of claim 8 is characterized by a vibration wave driving device in which the surface hardness of the iron or iron alloy is 600 or more in terms of Vickers hardness.

A ninth aspect of the present invention is a vibration wave driving device in which the iron alloy contains silicon in an amount of 1% by weight or more.

A tenth aspect of the invention is characterized by a vibration wave driving device in which the iron alloy contains 0.5% by weight or more of aluminum.

According to an eleventh aspect of the present invention, in a vibration wave drive device having a vibrating body that generates vibration and a contact body that is in contact with the vibrating body and relatively moves with the vibrating body due to the vibration, First contacting at least the contact body
And a second portion of the contact body that is in contact with at least the vibrating body are both made of an iron alloy of the same composition and the same hardness containing 1 wt% or more of silicon And

According to a twelfth aspect of the present invention, in a vibration wave drive device having a vibrating body that generates vibration and a contact body that is in contact with the vibrating body and relatively moves with the vibrating body due to the vibration, First contacting at least the contact body
And a second portion of the contact body that is in contact with at least the vibrating body, both containing 0.5 wt% of aluminum.
The vibration wave drive device is made of the iron alloy having the same composition and the same hardness contained above.

A thirteenth aspect of the invention is characterized by a vibration wave driving device using stainless steel as the iron alloy.

A fourteenth aspect of the invention is characterized by a vibration wave driving device in which the surface hardness of the iron alloy is 600 or more in Vickers hardness.

[0023]

[Embodiment] According to this embodiment, a frictional state that causes mild wear, which is called in the field of tribology, is maintained. The term "mild wear" is a term corresponding to "shibiya wear", and refers to a wear mode in which the generated wear particles are all oxides inside. The feature of this wear is that the size and wear amount of the wear powder are remarkably smaller than those of the chevron wear in which the wear powder is mainly composed of metal powder.

Therefore, it is desirable that the frictional form of the ultrasonic motor as the vibration wave drive device is mild wear.
The most suitable metal that is prone to mild wear is one containing iron, which belongs to the transition element, as a main component.

However, when the present inventor repeatedly conducted experiments under various conditions with the ultrasonic motor incorporating the friction material using iron or iron alloy, an unexpected phenomenon occurred. Simply put, there are two forms of mild wear.

First, there is an oxide film (which exhibits various colors depending on its thickness) generated by frictional heat on the friction surface.
The actual friction surface is in the state of its oxide film.

The other is a state in which the friction surface has an iron color (silver color).

The former occurred under very light friction conditions. That is, the condition is that the stress applied perpendicularly to the friction surface and the friction force applied in parallel are small, and the relative speed of the friction surfaces is small.

In this case, the actual friction occurs in the oxide film, and the frictional force is small. The oxide film seems to act as a lubricating film. And the abrasion powder could not be confirmed with an optical microscope. Probably very small. In fact, there is almost no wear, and the oxides that make up the oxide film may have repeatedly transferred to the friction surfaces of each other.

On the other hand, the friction in which the friction surface has a silver color occurred under a slightly more severe condition. Then, in this case, the frictional force was about twice that of the former state. A reddish brown rubbing powder is produced, but it is a very fine powder that is free flowing. Since it is an oxide such as Fe ₂ O ₃ or Fe ₂ O ₄ , the cohesive force may be small.

Both types of friction and wear are promising as friction of the ultrasonic motor. However, the problem is that the two friction, wear modes occur in one designed motor.

That is, the load applied to the motor and the operating speed (in the case of a rotary type motor, the number of revolutions) are not always constant within the life of one motor. As described above, the two types of friction have different friction coefficients, so that the motor performance is not constant.

The friction by the oxide film of the first embodiment is excellent because the friction coefficient is small but there is almost no wear, but the force for pressing the contact body against the vibrating body must be increased because the friction coefficient is small. However, there is also a disadvantage in the structure of the ultrasonic motor.

In this embodiment, it is proposed that the second mode can be maintained stably.

By this means, (1) the oxide film is scraped off by the mating friction material before the oxide film grows.

(2) The oxide film is scraped off by the generated friction powder.

Further, (3) an oxide film having a small friction coefficient is not formed by adding the special element.

That is.

(First Embodiment) FIG. 1 is a sectional view of an ultrasonic motor as a vibration wave driving apparatus using a friction material according to the embodiment. Reference numeral 1a is a friction material as a contact portion coupled to the vibrating body 1. That is, it becomes a friction material on the vibrating body side.
On the other hand, 2a is a friction material as a contact portion which is coupled to the moving body 2 as a contact body. That is, it becomes a friction material on the moving body side.

In the present embodiment, the ultrasonic motor is used, and the wear amount, the friction coefficient and the corrosion resistance are improved by conducting an experimental study by changing the friction materials on the vibrating body side and the moving body side in various ways. It proposes a material with desirable qualities as a friction material as a universal concept and numerical value.

As a friction material for an ultrasonic motor, it is desirable that it has high wear resistance and a stable friction coefficient. Furthermore, it is required that the performance does not change even in the environment of use of the motor.

The friction material used in this study was provided by cutting various iron-based materials. The vibrating body side friction member 1a has a disk shape with a hole at the center like a flat washer. This hole is used as a fitting part, and after this is bonded to the vibrating body 1, the friction sliding surface that makes frictional contact with the moving body side friction material 2a is set to 1
Lapping was performed with diamond abrasive grains of μm size.

On the other hand, the moving body side friction material 2a has a shape in which a circular pipe is cut into round pieces. This one end face makes frictional contact with the vibrating body side friction member 1a, and this face is preliminarily 1 μm.
Lapping is performed with m-sized diamond abrasive grains. After this, the moving body side friction material 2a is bonded to the moving body 2 by using the inner diameter portion as a fitting portion.

As described above, preparations for this study were completed. The details of the driving principle of the ultrasonic motor used in this study are described in Japanese Patent Application Laid-Open No. 3-117384, and therefore the description thereof is omitted here. In the embodiment, 3 is an electro-mechanical energy conversion element, which receives an alternating voltage and causes the vibrating body 1 to generate traveling wave vibration. Reference numeral 4 denotes a coil spring for pressing the moving body 2 against the vibrating body 1. Although the vibrating body 1 is fixed and the moving body 2 is rotated in the embodiment, the contact body 2 may be fixed and the vibrating body 1 may be rotated. Reference numerals 5 and 6 denote output gears of the driven object. , Output gears 5, 6
It becomes a system by including. In this study, the present ultrasonic motor was used, the friction materials were changed, and 11 combinations of friction materials were set.

The specifications of the iron-based material used as the friction material are shown in FIG. The results of examining the combinations of friction materials, their wear characteristics, the coefficient of friction, and the color of the friction sliding surface are shown in FIG.

The experiment was carried out in an indoor environment. The load torque was two conditions of 2 × 10 ⁻³ N · m and 6 × 10 ⁻³ N · m, and a load corresponding to each condition was applied to the output gear 5 from the output gear 6.

Under each of the conditions, the number of revolutions of the motor was set to 900 revolutions per minute (relative speed of the friction material was 0.4 m / s), and after 1 hour (relative movement distance of the friction material was 1440 m), the above items were examined. It was

The surface pressure applied to the friction sliding surface is 2 (P
a). Further, in the experimental examination under the above two conditions, the friction material was used in a new state, that is, after the lapping process was performed.

Here, the measurement conditions and the like of FIG. 3 showing the results of the above durability test will be described. The amount of wear was determined as the height of wear using a surface profiler. The amount of wear of the moving body side friction material was determined with reference to the reference surface 2b of the moving body. The friction coefficient is obtained by determining the droop curve of the motor speed-torque immediately after the end of the durability test, and using the maximum torque Tmax.

[0050]

[Outside 1] (W: pressure contact force of friction sliding surface, D: average diameter of friction sliding surface).

The numerical values are rounded to the nearest 0.05 unit. The color of the friction sliding surface was examined by optical microscope observation. For those exhibiting a blue color, it is considered to be the color of the oxide film generated by frictional heat. It was also found that the coefficient of friction was as small as about 0.25 when the material exhibited a blue color. Probably, this oxide film acts like a solid lubricant. It was also found that the amount of wear was significantly reduced when this blue color was exhibited.

In the table, the wear amount at this time is set to 0.1 μm or less, which is determined by the surface profile measuring machine to be the depth of relatively sharp scratches which are considered to have been in the “familiar” period of the friction surface at the initial stage of durability. Since it was close to 0.1 μm, it was displayed as such.

Although not shown in this table, the friction material sample No. Is No. on the vibrator side. 5 and the moving body side No. 500 under the condition of load torque of 2 × 10 ⁻³ N · m.
As a result of a durability test conducted for a time (relative movement distance of 730 km), the amount of wear was 0.1 μm, which was almost unchanged, and the color of the friction surface was not changed. In other words, the marvelous result is that wear is hardly generated once the condition that the color is blue is exhibited.

As long as the motor is used only under this condition, the friction coefficient is low, but it is extremely effective as a friction material for an ultrasonic motor. This embodiment proposes a friction material capable of simultaneously maintaining a small amount of wear and a stable friction coefficient against various loads applied to the friction surface.

Regarding the judgment, under the condition of 6 × 10 ⁻³ N · m, the wear amount of both the vibrating body side friction material and the moving body side friction material is 10 μm or less, ⊚, 10 to 30 μm is ◯, and 30 to 100.
Although μm Δ and more were designated as x, neither Δ nor x were found in this study.

The stability of the motor performance corresponds to the fact that the friction coefficient is constant under each condition. In this study, there was no constant friction coefficient of about 0.25.

As the friction material of the motor, it is necessary to satisfy a small amount of wear and stable motor performance at the same time.
As a comprehensive evaluation, items with poorer judgments were evaluated. From the above, in the present study, a friction material in which the friction surface was always silver (metal color) and the friction coefficient was maintained at a relatively high level of about 0.55 was selected.

Separately from this examination, a motor in which each friction material was combined was used with a relative humidity of 90% and a temperature of 70 ° C.
After being left for a long time under the environment of No. 3, the drooping characteristics of the motor did not differ from the performance before being left. Regarding 1 to 4, rust was generated. Sample No.
No rust was found on any of the 5 to 10 stainless steels.

However, stainless steel containing molybdenum (elemental symbol Mo) in an amount of about 1 to 3% is more desirable in order to withstand use in a more severe environment. This is also an effective element against "crevice corrosion" that tends to occur when there is a small space on the friction sliding surface.

It was also found that the condition of exhibiting a blue color is likely to occur when the same material is used for both the vibrating body side friction material and the moving body side friction material.

However, when the hardnesses of one of them are different even if they have the same composition, or when aluminum (Al) or silicon (Si) is contained as a component, alumina (Al ₂ O ₃ ) and glass (SiO ₂ ) are said to be produced, and it is considered that these suppress the growth of iron oxide films such as Fe ₂ O ₃ and Fe ₃ O _4, so it was found that they do not exhibit blue color.

Regarding the hardness of the friction material, it has been found that the harder it is, the less the amount of wear is, under the condition that it exhibits a silver color.
It is desirable that the Vickers hardness is 600 or more.

Further, the one having the same hardness and using carbon steel as one friction material and martensite stainless steel as the other friction material has a silver surface on the friction surface even after the durability test under a low torque load. Was present.

It is presumed that, because the components become black mutually, a difference occurs in the rate of formation of the oxide film and its physical properties, and one of them scrapes off the other. Then, once scraped off, it becomes fine oxidative wear powder, which acts like abrasive grains during lapping and has the effect of abrading even a hard partner.

However, in the case of iron, this oxide powder is considered to be relatively soft, and if the iron base material has a martensitic structure, a Vickers hardness of 600 or more can be easily obtained. With powder, the base material itself does not easily wear out. Therefore, it seems that the wear resistance is high.

(Second Embodiment) FIG. 5 shows the combination of friction materials used in the second embodiment and the result of the durability test. Since the description of this table is the same as that of the first embodiment, it is omitted here.

One of the friction materials is an iron material. On the other hand, only a hard coating having a Vickers hardness of 800 or more was selected and formed on the surface of the moving body side friction shape member cut or sintered by the base material described in the remarks of FIG.

The surface corresponding to the friction sliding surface is set to 1
After lapping using diamond abrasive grains of μm size,
It was adhered to the moving body 2. Here, the Vickers hardness is 800
The reason for limiting the above is that in the first embodiment, the higher the hardness of the friction material, the smaller the friction amount, and if the friction material on the vibrator side is made of a softer coating than the iron-based material. This is because if this film is formed, the amount of wear of this film is larger than that of the mating material, and the life of the motor is determined by whether or not this film remains.

This is also the case with cermets and ceramics, because the performance exceeding that of the first embodiment cannot be obtained unless a hard material is used. Note that these cermets and ceramics are produced by sintering and are subjected to the above-mentioned lapping.

Further, all the friction materials having Vickers hardness of 800 or more are arranged as the moving body side friction material, but the load applied to the friction material is relative, and even if they are arranged as the vibrating body side friction material. Similar results should be obtained.

The reason why the nitride film is formed on SUS316 which is a stainless steel having extremely high corrosion resistance is as follows. That is, similarly to the carburized film, when nitrogen or carbon diffuses into stainless steel, it is combined with chromium in stainless steel to form chromium carbide or nitride, and in the vicinity thereof, chromium is deficient and corrosion resistance is significantly reduced.

Therefore, the use of stainless steel having a large amount of Ni and Mo added to enhance the corrosion resistance resulted in the reduction of the corrosion resistance. Three kinds of materials were selected as the base material of titanium nitride, but 400 to 500 was used when forming this film.
Since the temperature of ° C is applied, the decrease in hardness of the base material becomes a problem.

In the present examination, only the cermet (carbide) on which the hardness was not reduced had the coating formed thereon, the TiN coating remained even after the high torque load test. Since the coating thickness is thin, the hardness (deformation resistance) of the base material seems to be related to wear.

Those using ceramics (alumina) had a high friction coefficient and were further excellent in wear resistance.
The wear of the counterpart carbon tool steel is smaller than that of tungsten-carbide (WC), which has a hardness equal to or higher than that of alumina. It is considered that this is because chemical abrasion did not occur because the alumina is an oxide and hardly dissolves in iron.

Silicon carbide (SiC) and silicon nitride (Si
_{Even if} other ceramics such as ₃ N ₄ ) are used, their hardness is 1000 or more in terms of Vickers hardness, so that the abrasive wear resistance is high and the wear amount is considered to be equivalent to WC (tungsten carbide).

(Third Example) Assuming that the friction material on the moving body side and the friction material on the oscillator side have the same composition and the same hardness, a study is made on a motor using a friction material made of stainless steel containing aluminum or silicon. did. as a result,
Under all conditions, the friction sliding surface had a silver color.

This is because Al ₂ O ₃
An SiO ₂ film is formed on the surface by the film and silicon, and since the self-diffusion coefficient of these films is extremely small, the film itself is extremely thin compared to the oxide film of iron, and the iron oxide film (Fe _It is considered that there is a property different from that of ₂ O ₃ , Fe ₃ O ₄ ).

(Fourth Embodiment) A fourth embodiment of FIG. 7 is an example in which the friction material of the above-mentioned embodiment is used in a ring-shaped ultrasonic motor as a ring-shaped vibration wave driving device. The details of the driving principle are already known, as disclosed in Japanese Patent Laid-Open No. 59-201685.

In the embodiment, 11 is a vibrating body, and a large number of protrusions are formed, and the tips of the protrusions, that is, the contact portions, are fixed with the friction material 11a made of the same material as the friction material 1a described above. There is. Reference numeral 12 is a moving body as a contact body, and a friction material 12a made of the same material as the friction material 2a described above is fixed to the contact portion. Reference numeral 13 denotes an electro-mechanical energy conversion element fixed to the vibrating body 11, which receives an alternating voltage and generates a progressive vibration wave on the protrusion of the vibrating body 11. Of course, also in the second embodiment, if the vibrating body 11 is fixed, the contact body 12 rotates, and if the contact body 12 is fixed, the vibrating body 11 rotates.

[0080]

As described above, according to the present invention,
At least one of the two contact portions of the vibration wave driving device in contact with each other is made of iron or iron alloy, and the other is (1) iron or iron alloy having a different component or surface hardness from the iron or iron alloy ( 2) Metal or ceramic or cermet having a surface hardness of 800 or more in Vickers hardness (3) A material having the same composition and hardness as the iron or iron alloy. However, those containing aluminum or silicon as a component.

By using the above, "oxidative wear" (a kind of mild wear) having a very low wear rate peculiar to iron is generated, thereby providing a vibration wave drive device having a long life, low cost, and high environmental resistance. To do.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an ultrasonic motor used for studying the present invention.

FIG. 2 is an enlarged sectional view of a friction portion in the ultrasonic motor.

FIG. 3 is a view showing a combination of friction materials examined in the first embodiment and a result.

FIG. 4 is a diagram showing specifications of a friction material examined.

FIG. 5 is a diagram showing a combination of friction materials examined in the second embodiment and a result.

FIG. 6 is a view showing a combination of friction materials examined in the third embodiment and a result.

FIG. 7 is an explanatory diagram of an ultrasonic motor used in a fourth embodiment.

[Explanation of symbols]

 1 Vibrating body 1a Vibrator side friction material 2 Moving body 2a Moving body side friction material A Friction sliding surface

Claims (14)

[Claims] 1. A vibration wave drive device comprising: a vibrating body that generates vibration; and a contact body that is in contact with the vibrating body and moves relative to the vibrating body due to the vibration, at least the contact body of the vibrating body. Both the first portion that comes into contact and the second portion that comes into contact with at least the vibrating body of the contact body are made of iron or an iron alloy, and they have different compositions (components) from each other. Vibration wave drive device. 2. A vibration wave drive device comprising: a vibrating body that generates vibration; and a contact body that is in contact with the vibrating body and moves relative to the vibrating body due to the vibration, at least the contact body of the vibrating body. An oscillating wave characterized in that both the first portion that comes into contact with the second portion that comes into contact with at least the vibrating body of the contact body are made of iron or an iron alloy, and their surface hardnesses are different. Drive. 3. The vibration wave driving device according to claim 1, wherein stainless steel is used as the iron alloy. 4. The vibration wave according to claim 1, wherein at least one of the first portion and the second portion is an iron alloy containing silicon in an amount of 1% by weight or more. Drive. 5. The iron alloy containing 0.5% by weight or more of aluminum is used for at least one of the first portion and the second portion.
The vibration wave driving device described. 6. A vibration wave drive device comprising: a vibrating body that generates vibration; and a contact body that comes into contact with the vibrating body and moves relative to the vibrating body due to the vibration, at least the contact body of the vibrating body. A first portion that comes into contact with the first body and at least one of the second portions that comes into contact with the vibrating body of the contact body are a cermet that is a metal, ceramic, or a composite material thereof having a Vickers hardness of 800 or more. A vibration wave drive device characterized in that the other is made of iron or an iron alloy. 7. The vibration wave driving device according to claim 6, wherein stainless steel is used as the iron alloy. 8. The vibration wave drive device according to claim 6, wherein the iron or iron alloy has a surface hardness of 600 or more in Vickers hardness. 9. The vibration wave driving device according to claim 6, wherein the iron alloy contains silicon in an amount of 1% by weight or more. 10. The iron alloy contains 0.5 aluminum.
7. The composition according to claim 6, wherein the content is at least wt%.
The vibration wave driving device according to 7 or 8. 11. A vibration wave drive device comprising: a vibrating body that generates vibration; and a contact body that is in contact with the vibrating body and that moves relative to the vibrating body due to the vibration, at least the contact body of the vibrating body. A first portion that comes into contact with the second portion of the contact body that comes into contact with at least the vibrating body;
Both of them are vibration wave drive devices, characterized in that they are iron alloys having the same composition and the same hardness, containing 1% by weight or more of silicon. 12. A vibration wave drive device comprising: a vibrating body that generates vibration; and a contact body that is in contact with the vibrating body and moves relative to the vibrating body due to the vibration, at least the contact body of the vibrating body. A first portion that comes into contact with the second portion of the contact body that comes into contact with at least the vibrating body;
Both are made of an iron alloy having the same composition and the same hardness, containing aluminum in an amount of 0.5% by weight or more. 13. The vibration wave driving device according to claim 11, wherein stainless steel is used as the iron alloy. 14. The iron alloy according to claim 11, wherein the surface hardness is 600 or more in Vickers hardness.
The vibration wave driving device according to 2 or 13.