JP2000278973A - Frictional material for oscillatory motor, and its manufacture, and oscillatory motor and apparatus using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide frictional material for an oscillatory motor whose endurance life is long and which can perform stable drive. SOLUTION: This is frictional material 6 which is provided at the frictional contact part of at least either an oscillator or a contactor, in an oscillatory motor where the oscillator 1 exciting oscillation and the contactor 14 to contact with the oscillator slide relatively, and the frictional material consists of a composite baked body being obtained by lowering the temperature at a temperature drop speed of 20 deg.C/Hr or under from the vicinity of fusion point of fluororesin to normal temperature after preliminairly compressing the composite material having fluororesin for its main component and baking it.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a friction material for a vibration motor, a method for manufacturing the same, a vibration motor and a device using the same.

[0002]

2. Description of the Related Art Generally, a vibration motor such as a vibration wave motor
Circular or elliptical motion is excited on the surface particles of the vibrating body, and the contacting body that has come into pressure contact with the vibrating body and the vibrating body relatively move by friction driving. Therefore, it is desirable to provide a material having a large friction coefficient as a friction material at the pressure contact portion of the vibrating body and the contact body in order to efficiently extract the output of the vibration motor, and the wear of the friction material directly leads to the durable life of the motor. Therefore, a material with little wear is desirable. Therefore, various organic materials, inorganic materials, and metallic materials have been conventionally proposed as friction materials.

Specifically, for example, a heat-resistant resin such as polyimide, polyamide imide, polyether imide, or epoxy is used as a base material, and further, a carbon fiber, an inorganic filler and a fluororesin are added to these as a filler. Is used. As a particularly practical friction material, a material made of a fluororesin containing a heat-resistant filler has been proposed. (Japanese Unexamined Patent Publication No. 1-129981)

[0004]

However, the friction material using the heat-resistant resin of the prior art as a base material does not have a good balance of the coefficient of friction, stability, abrasion resistance, and starting stability. In particular, when driven for a long time, there is a problem that the wear resistance is insufficient and a problem that stable driving of the vibration motor cannot be obtained due to wear powder.

A friction member made of a fluororesin and a heat-resistant filler has a high coefficient of friction to some extent and has better abrasion resistance and driving stability than those described above. There is a problem that the abrasion resistance changes greatly depending on the manufacturing conditions.

The present invention has been made to solve such problems of the prior art, and has improved a friction material comprising the above-mentioned fluororesin and a heat-resistant filler to provide a long durable life and a stable life. An object of the present invention is to provide a friction material for a vibration motor that can be driven, a method of manufacturing the same, a vibration motor and a device using the same.

[0007]

That is, the present invention relates to a vibration motor in which a vibrating body whose vibration is excited and a contact body that comes into contact with the vibrating body slide relative to each other. A friction material provided on at least one of the friction contact portions, wherein the friction material is pre-compressed and baked from a composite material containing a fluororesin as a main component, and then has a temperature of 20 ° C./Hr or less from the vicinity of the melting point of the fluororesin to room temperature A friction material for a vibration motor, comprising a composite fired body obtained by lowering the temperature at a lowering rate.

Further, the present invention provides a vibration motor in which a vibrating body in which vibration is excited and a contact body in contact with the vibrating body slide relative to each other, wherein at least one of the vibrating body and the contact body has a frictional contact portion. In the method for producing a friction material provided in the above, after pre-compressing the composite material containing a fluororesin as a main component, raising the temperature to a temperature equal to or higher than the melting point of the fluororesin, and sintering, the temperature is increased by 20 ° C. A method for producing a friction material for a vibration motor, characterized in that the temperature is decreased at a rate of not more than / Hr.

Further, the present invention provides a vibration motor in which a vibrating body in which vibration is excited and a contact body in contact with the vibrating body slide relative to each other, wherein at least one of the vibrating body and the contact body has a frictional contact portion. And a friction motor provided with the friction material.

Further, the present invention is an apparatus characterized in that the above-mentioned vibration motor is provided as a drive source.

In the present invention, it is preferable that the composite material containing the fluororesin as a main component is pre-compressed, and then heated to a temperature higher than the melting point of the fluororesin and fired. It is preferable that the composite material containing a fluororesin as a main component contains at least one selected from carbon fiber, polyimide and molybdenum sulfide in addition to the fluororesin as a main component.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to achieve the above object, a first solution of a vibration motor according to the present invention is that a vibration body whose driving is excited and a contact body which comes into contact with the vibration body are relatively slid. In a moving vibration motor, at least one of the vibrating body and the contact body is provided with a friction material on a sliding portion, and the friction material is a composite material containing a fluororesin as a main component. A friction material for a vibration motor characterized in that the material is a composite fired body obtained by firing the material after pre-compression and then lowering the temperature from around the melting point of the fluororesin to room temperature at a temperature lowering rate of 20 ° C./Hr or less. .

In this solution, the friction material provided at at least one of the frictional contact portions of the vibrating body and the contact body is a composite material containing a fluororesin as a main component and further containing a heat-resistant filler and the like. After firing, it is a composite fired body obtained by lowering the temperature from around the melting point (about 328 ° C.) of the fluororesin to room temperature at a temperature lowering rate than 20 ° C./Hr. No peeling due to the difference in expansion coefficient occurs. Therefore, the mating material is not damaged by the heat-resistant filler coming off, and the friction material itself is not worn, thereby improving the wear resistance of the friction material. At the same time, the durability and drive stability of the drive motor can be improved. Also, the fluororesin itself is 20 ° C / Hr
Thereafter, by lowering the temperature slowly at a temperature lowering rate of preferably 5 to 20 ° C./Hr, no residual stress remains inside and the wear resistance is also improved.

Further, in the friction material of the present invention, in addition to the fluororesin as the main component, at least one selected from carbon fiber, polyimide and molybdenum sulfide is used as the composite material containing the fluororesin as the main component. It is preferable to use one containing a kind. Since this friction material is composed of a composite fired body containing at least one of carbon fiber, polyimide and molybdenum sulfide in addition to the fluororesin as a main component, the friction material has abrasion resistance and friction stability. , And the durability and driving stability of the vibration motor can be improved at the same time.

The content of the fluororesin contained in the composite material is desirably in the range of 50 to 95% by weight, preferably 70 to 90% by weight, and the content of at least one of carbon fiber, polyimide and molybdenum sulfide is preferably The range is 5 to 50% by weight, preferably 10 to 30% by weight.

Next, a vibration motor using the friction material of the present invention will be described. FIG. 1 is a schematic diagram showing one embodiment of the vibration motor of the present invention. FIG. 1A shows a first embodiment of the present invention.
Ring type vibration motor (vibration type driving device) according to an embodiment
FIG. In the figure, reference numeral 3 denotes a ring-shaped elastic body made of metal or the like. On the lower surface of the elastic body 3, a piezoelectric element group 4 in which two groups of piezoelectric elements alternately polarized are arranged in a ring shape is adhered concentrically. The upper portion of the elastic body 3 is formed in a comb-like shape in order to increase the vibration amplitude, and a friction material 6 is concentrically adhered to the upper surface of the comb-like portion. The vibrating body 1 is constituted by the elastic body 3, the piezoelectric element group 4, and the friction material 6. Also, the elastic body 3
Of the vibrating body 1 is fixed to the base member 10 by screws 13.

Reference numeral 14 denotes a contact body. This contact body 14
The ring portion 2 has a disk-shaped spring portion 5 in which an inner peripheral boss portion 7 is spline-coupled to the motor output shaft 11. The ring portion 2 is pressed by the spring portion 5 to cause the ring portion 2 to vibrate the vibration body 1 (friction material 6). Is pressed against. The spring portion 5 is elastically deformed when the inner peripheral boss portion 7 is pushed downward by the upper bearing 9 of the motor output shaft 11 in the motor axial direction, and generates the above-described pressing force.

In the vibration motor configured as described above, when two high-frequency signals having different phases are applied to the piezoelectric element group 4, circumferential traveling waves are generated in the elastic body 3 and the friction material 6. Therefore, the contact body 1 pressed against the friction material 6
4 is rotationally driven while sliding on the friction material 6 by friction with the friction material 6, and this rotation is transmitted to the motor output shaft 11 via the spring portion 5 and the boss portion 7 to generate a motor output. It is taken out and used as a driving force of a driving target in the apparatus.

FIG. 1B is an enlarged view of a sliding portion of the vibration motor of the present embodiment. In FIG. 1B, a friction member 2a is disposed on the sliding portion side of the ring portion 2 which is a part of the contact member 14 made of an aluminum alloy, and is in pressure contact with the friction member 6 on the vibration body 1 side. are doing. In the present embodiment, the friction material 6 is provided with the circumferential step 6a, but the present invention is not limited to this, and the shape of the friction material 6 is arbitrary.

The friction material of the present invention may be used for both the friction material 6 and the friction material 2a of the ring portion 2, or may be used for either one of them.

When the friction material of the present invention is used on one side, a normal friction material can be used on the other side. Examples of ordinary friction materials include aluminum-silicon alloys that are hard, tough, and hardly wear, hardened steel, ceramics, and cemented carbides.

The present invention can be applied to various devices to be driven shown in FIG. 1 using a vibration motor provided with the above-mentioned friction material as a driving source. Specific examples of the equipment include optical equipment such as a camera, office equipment such as a printer and a copying machine, and automobile-related equipment such as a power window and an active suspension.

[0023]

The present invention will be described more specifically with reference to the following examples.

Example 1 First, an example in which the temperature reduction rate after firing in the production of a composite fired body as a friction material was described. A friction material was prepared as follows.

80% by weight of a fluororesin (polytetrafluoroethylene, hereinafter abbreviated as PTFE) powder and 20% by weight of carbon fiber (MC-249, manufactured by Osaka Gas Co., Ltd.)
%, And after mixing sufficiently uniformly, at 500 kg / cm ² ,
A compact having a diameter of 8 cm, an inner diameter of 1 cm, and a height of 10 cm was prepared by pre-pressing with a press, and fired according to the temperature pattern shown in FIG.

First, in step 1, the temperature is raised from room temperature (20 ° C.) to 320 ° C. near the melting point of PTFE at a rate of 60 ° C./Hr. 3Hr at 320 ° C to reach temperature
Held. In Step 3, the temperature was raised from 320 ° C. to 380 ° C. at a rate of 20 ° C./Hr, and in Step 4, the maximum temperature was maintained at 380 ° C. for 3 hours. Thereafter, the temperature was lowered, and the temperature was lowered at 20 ° C./Hr in Step 5, and the temperature lowering rate in Step 7 was changed from 5 ° C./Hr to 60 ° C./Hr to obtain seven types of cylindrical fired bodies. In addition, between step 5 and step 7, step 6 near the melting point of PTFE is performed by step 6.
A retention time of 3 hr at 20 ° C. is included.

Here, even if the heating rates in Steps 1 and 3 are changed by a preliminary experiment, the influence on the wear is small, and in the present embodiment, the above values are kept constant. Further, in step 5, the influence of the cooling rate on the wear was small, so that the temperature was kept constant. Similarly, except for the extremely short holding time of steps 2, 4, and 6, the effect on wear was small, and finally, only the temperature lowering rate in step 7 had a large effect on wear.

After the completion of firing, the above seven types of cylindrical fired bodies were cut into a ring shape by a cutting device, and circular sheets having a thickness of 0.5 mm were prepared. Was used as the ring-shaped friction material 6. The shape of the friction material 6 is, as shown in FIG.
a is provided by cutting or the like, and the height c is 0.15 mm. The width a of the contact portion (sliding portion) between the friction material 6 and the friction material 2a of the ring portion 2 is 0.8 mm, and the diameter b of the contact portion is 30.
mm.

The friction material 6 is fixed to a metal elastic body 3 made of stainless steel with an adhesive, and the friction material 2a of the ring portion 2 made of an aluminum alloy is formed by using tungsten carbide containing cobalt by thermal spraying. The vibration motor shown in FIG.

Hereinafter, the evaluation of the friction material 6 in the first embodiment is performed by setting the vibration motor at a rotation speed of 300 rpm and a torque of 30 rpm.
This is a value obtained after driving for 100 hours at 0 gw · cm. The result is shown in FIG.

FIG. 3 shows the amounts of wear of the seven types of friction materials obtained by firing and working according to the above-described procedure after driving for 100 hours. Here, the amount of wear is shown in FIG.
The height c of the step 6a is measured in advance by a height gauge before driving, and is obtained as a value obtained by subtracting the height after driving from the height c.

As can be seen from FIG. 3, it was found that the abrasion after driving for 100 hours rapidly increased when the temperature drop rate in step 7 exceeded 20 ° C./Hr, and continued to increase to about 50 ° C./Hr. The reason why the amount of wear increases when the cooling rate is increased is that peeling occurs between the PTFE and the carbon fiber due to the difference in the coefficient of thermal expansion between the two,
It is considered that a sudden cooling causes residual stress to remain inside the PTFE and a decrease in the crystallinity of the PTFE.

Embodiment 2 Next, a second embodiment will be described.

(Example 2-1) As the friction material 6, PTF was used.
20 wt% of carbon fiber (manufactured by Osaka Gas Co., Ltd., trade name: MC-249) is sufficiently uniformly mixed with 80 wt% of E resin powder, and then prepressurized with a press at 500 kg / cm ² to obtain a diameter of 8 cm. Then, a molded body having an inner diameter of 1 cm and a height of 10 cm was produced, and firing was advanced to Step 6 according to the temperature pattern shown in FIG. After that, the cooling rate in step 7 is set to 2
At 0 ° C./Hr, a cylindrical fired body was obtained. The fired body was cut into a ring shape by a cutting device to produce a circular sheet having a thickness of 0.5 mm. Next, after the sheet was punched, the step 6a was cut with the same dimensions as in Example 1 to obtain a friction material A.

(Example 2-2) As the friction material 6, PTF was used.
After thoroughly mixing 10 wt% of carbon fiber (manufactured by Osaka Gas Co., Ltd., trade name MC-249) and 10 wt% of molybdenum disulfide to 80 wt% of E resin powder, Example 2-
Baking, cutting, punching and stepping 6 in the same procedure as in 1.
a was cut to obtain a friction material B.

(Example 2-3) As the friction material 6, PTF was used.
After mixing E fiber powder 70 wt%, carbon fiber 20 wt%, molybdenum disulfide 5 wt% and polyimide 5 wt% sufficiently uniformly, firing is performed in the same procedure as in Example 2-1.
Cutting, punching and cutting of the step 6a are performed, and the friction material C
I got

(Comparative Example 2-4) As the friction material 6, PTF was used.
After sufficiently mixing 10 wt% of carbon fiber and 10 wt% of molybdenum disulfide with 80 wt% of E resin powder, FIG.
According to the temperature pattern shown in FIG. Thereafter, firing was performed at a temperature lowering rate of 40 ° C./Hr in Step 7, and thereafter, a friction material D was obtained according to the same procedure as in Example 2-1.

(Comparative Example 2-5) As the friction material 6, PTF was used.
After sufficiently mixing 20 wt% of carbon fiber, 5 wt% of molybdenum disulfide and 5 wt% of polyimide with 70 wt% of E resin powder, firing was advanced to step 6 according to the temperature pattern shown in FIG. Thereafter, firing was performed at a temperature lowering rate of 40 ° C./Hr in Step 7, and thereafter, a friction material E was obtained according to the same procedure as in Example 2-1.

The friction materials A to C obtained by the procedures of Examples 2-1 to 2-3 and the friction materials D and E obtained by the procedures of Comparative Examples 2-4 and 2-5 were used in Examples. 1 as in FIG.
Vibration motors were each manufactured using the friction material 6 of (b).

Each of the vibration motors is rotated at a rotational speed of 300 rpm.
After driving for 100 hours at m and torque of 300 gw · cm, the same evaluation as in Example 1 was performed. Table 1 shows the results.

[0041]

[Table 1]

Table 1 lists the production conditions of Examples 2-1 to 2-3 and Comparative Examples 2-4 and 2-5 and the results of the evaluation. 10μ wear on the side
未 満: less than 10 μm and less than 20 μm, ×: 30 μm or more.

Comparing Examples 2-1 to 2-3 in Table 1, even if the "temperature lowering rate during firing" (step 7) is the same value, carbon fiber as an additive to the friction material is used. It was found that the addition of polyimide powder and molybdenum disulfide changed the wear resistance and friction stability.

That is, in Examples 2-2 and 2-3 in which molybdenum disulfide and polyimide powder were added in addition to carbon fiber,
The abrasion resistance was lower than that of Example 2-1 in which both were not added. On the other hand, Comparative Examples 2-4 and 2-5 have the same composition ratio as Examples 2-2 and 2-3 with the least amount of wear, respectively. 20 ° C
By increasing from / Hr to 40 ° C./Hr, the amount of wear showed an order of magnitude larger value.

Further, the friction material 2a of the ring portion 2 sliding with the friction material 6 is a hard coating of tungsten carbide, but the comparative examples 2-4 and 2-5 in which the friction material 6 has a large wear amount.
In, scratches on the order of submicron were observed on the sliding surface on the friction material 2a side. This is because, when the above-mentioned “temperature decrease rate during firing” rises to 40 ° C./Hr, peeling occurs due to the difference in the coefficient of thermal expansion between PTFE and the carbon fiber, and the carbon fiber comes off and comes into contact. It is considered that the friction material 2a on the body side was damaged.

Thus, in the vibration motors of Comparative Examples 2-4 and 2-5, the fluctuations in torque and rotation are several times larger than those of Examples 2-1 to 2-3 in Table 1. It was observed that the stability of the drive of the vibration motor was impaired.

The present invention can be used for at least one of the friction material 6 and the friction material 2a. Examples 1 and 2
In this case, the friction material 6 and the friction material 2a are exchanged, and the friction material of the composite fired body of the present invention is used for the friction material 2a on the ring portion 2 side, and a hard coating or the like is used for the friction material 6 on the metal elastic body 3 side. You may. Further, the friction material of the composite fired body of the present invention may be used for both the friction material 6 and the friction material 2a.

In this embodiment, the friction material of the present invention is shown in FIG.
The example applied to the disk-shaped vibration motor shown in
In addition, the friction material of the present invention can be applied to a rod-shaped vibration motor or a linear vibration motor in the same manner.

[0049]

As described above, according to the present invention, the friction material disposed on at least one of the vibrating body and the contact body of the vibration motor is a composite material mainly composed of fluororesin. At the same time, after firing, the composite fired body is obtained by lowering the temperature from around the melting point of the fluororesin to a temperature lower than 20 ° C./Hr, so that the abrasion resistance is good and the durability life of the vibration motor is significantly longer than that of the conventional example. Thus, the effect of improving the driving stability can be obtained.

Further, since the friction material of the present invention is a composite molded body containing at least one of carbon fiber, polyimide and molybdenum sulfide in addition to the fluororesin as a main component, the durability life of the vibration motor is improved. The effect of further greatly improving the driving stability is obtained. Also, the present invention
It is possible to provide a device using a vibration motor provided with the friction material and having excellent durability life and drive stability.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an embodiment of a vibration motor according to the present invention.

FIG. 2 is a diagram showing the relationship between the firing temperature and the time of the friction material of Example 1 and Example 2 of the present invention.

FIG. 3 is a diagram illustrating a relationship between a temperature decrease rate and a wear amount of the friction material according to the first embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vibration body 2 Ring part 2a Friction material on ring side 3 Elastic body 4 Piezoelectric element group 5 Spring part 6 Friction material 6a Step 7 Inner peripheral boss part 8 Lower bearing 9 Upper bearing 10 Base member 11 Motor output shaft 12 Bowsing 13 Screw 14 Contact

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F071 AA27 AA60 AB03 AB20 AD01 AG28 AH12 DA01 DA13 DA14 5H680 AA00 AA12 BB03 BB13 BB16 BC04 BC05 CC07 DD01 DD02 DD23 DD53 DD55 DD66 DD73 DD87 DD92 EE03 FF04 FF16 FF13 FF33 FF13 FF33 GG25 GG27 GG41 GG43

Claims (6)

[Claims] In a vibration motor in which a vibrating body in which vibration is excited and a contact body that comes into contact with the vibrating body relatively slide,
A friction material provided in at least one of the friction contact portions of the vibrating body and the contact body, wherein the friction material is pre-compressed and baked from a composite material containing a fluororesin as a main component, from the vicinity of the melting point of the fluororesin. A friction material for a vibration motor, comprising a composite fired body obtained by lowering the temperature to a normal temperature at a temperature lowering rate of 20 ° C./Hr or less. 2. The friction material for a vibration motor according to claim 1, wherein after preliminarily compressing the composite material containing a fluororesin as a main component, the composite material is heated to a temperature higher than a melting point of the fluororesin and fired. 3. The composite material containing a fluororesin as a main component contains at least one selected from carbon fiber, polyimide and molybdenum sulfide in addition to the fluororesin as a main component. The friction material for a vibration motor according to the above. 4. A vibration motor in which a vibrating body in which vibration is excited and a contact body in contact with the vibrating body relatively slide.
In the method of manufacturing a friction material provided on at least one of the frictional contact portions of the vibrating body and the contact body, the composite material containing a fluororesin as a main component is pre-compressed and heated to a temperature equal to or higher than the melting point of the fluororesin. A method for producing a friction material for a vibration motor, comprising, after firing, lowering the temperature from the vicinity of the melting point of the fluororesin to room temperature at a temperature lowering rate of 20 ° C./Hr or less. 5. A vibration motor in which a vibrating body in which vibration is excited and a contact body in contact with the vibrating body relatively slide.
A vibration motor, comprising: the friction member according to claim 1 provided on at least one friction contact portion of the vibration body and the contact body. 6. An apparatus provided with the vibration motor according to claim 5 as a drive source.