JPH0433578A - Stator for ultrasonic motor - Google Patents

Abstract

PURPOSE:To prevent an insufficiency of a predetermined torque value due to a frictional damage, an increase in lubricity, etc., in a contact surface with a rotor by immersing a low melting point material in a cavity generated on the surface of a material sintered after power material is pressure molded. CONSTITUTION:A stator of an ultrasonic motor is formed of a sintered material representatively of an iron material containing stainless steel, copper material including brass, bronze material in such a manner that a low melting point material has a lower melting point than that of the sintered material itself, copper, tin, or lead material is used as the iron sintered material and tin or lead terminal is used as the copper material. Immersing material is immersed into cavities of the sintered material to eliminate residue in the cavities of the stator made of the sintered material, and only the immersed material is melted and immersed to the sintered material without remelting the sintered material. Thus, its thermal conductivity is improved to improve cooling properties, its temperature rise at the time of rotation of the motor is suppressed, and even if it is operated continuously for a long period, a predetermined torque value is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a stator for an ultrasonic motor.

[Prior Art] Currently, ultrasonic motors that utilize traveling waves are widely used in various fields. A typical configuration of this ultrasonic motor is shown in FIG. 2 is an output shaft which is rotatably supported by a disk-shaped base 2 via a bearing 3, and a disk-shaped stator 4 is fixed on one surface of the base 2 coaxially with the output shaft. On one surface of the stator 4, there is an annular disc-shaped rotating body 5 having almost the same external shape as the stator 4, which is coaxial with the output shaft 1 and whose negative surface (lower surface as seen in FIG. 2) is coaxial with the output shaft 1. ,
It is placed so as to be in contact with one surface of the stator 4 (the upper surface as seen in FIG. 2). The top of the output shaft 1 and the other surface of the rotating body 5 (
As an elastic body for elastically connecting them, a disc spring 6 is arranged in an elastic state between the top surface and the top surface as seen in FIG. It is locked to the shaft 1 and the rotating body 5. Furthermore, an annular piezoelectric element 7 having electrostrictive properties is fixed to the other surface of the stator 4 (the lower surface as viewed in FIG. 2). In addition, these stators
4. The rotating body 5, the disc spring 6, etc. are housed inside a cylindrical case 8, and the open end of the case 8 is fixed to the outer peripheral edge of the base 2. The end portion of the case 8 is rotatably supported via a bearing 3 installed at the center of the bottom of the case 8.

The ultrasonic motor having such a configuration vibrates one surface of the stator 4 (as shown in FIG. 2) by vibrating the stator 4 using a piezoelectric element 7 fixed to the other surface (the bottom surface as seen in FIG. 2). This traveling wave is transmitted to the rotating body 5 which is in pressure contact with the stator 4 via the disc spring 6, and is further transmitted to the output shaft l via the disc spring 6. It is used to transmit and extract a predetermined rotational torque.

If the stator, which is one of the important parts of this ultrasonic motor, is made of a melted alloy material and its entire shape is formed by cutting, the processing cost will be high. Therefore, in order to avoid a rise in cutting costs, it is common practice to use a powder material, pressure-form it into a desired shape, and sinter it.

[Problems to be Solved by the Invention] The above-mentioned sintered material does not require cutting, etc., and the desired product can be obtained with only simple finishing processing, so although the cutting cost can be reduced, it is not suitable for use as a sintered material. There is a problem with this.

In other words, sintered materials inevitably have pores inside, but the abrasive grains, cutting fluid, and
Polishing liquid or the like will enter the pores of the sintered material and remain there. Some of these residues reach deep pores, and it is difficult to remove all of them.

However, if such residual materials are present in the holes of the stator, when the stator is assembled into an ultrasonic motor and rotated, the residual materials ooze out from the holes of the stator due to frictional heat, etc., and damage the rotating body. Contact and adhere to the contact surface, causing scratches or increasing slipperiness, making it impossible to obtain the required torque value. Furthermore, when the cutting tool crosses the hole during finishing, it is constantly subjected to micro-impacts, resulting in a very short life span of the processing blade. Furthermore, when the motor rotates, the resonance point changes due to the generation of frictional heat between the stator and the rotating body and internal heat generation of the stator due to high frequency vibration, making it impossible to obtain the required torque value.

Therefore, the present invention aims to solve the above-mentioned problems by eliminating residual materials in the cavities of the stator made of sintered material, and to obtain the required torque value even after long-term operation. .

[Means for Solving the Problems] The present invention is characterized in that a low melting point material is infiltrated into the pores that inevitably occur on the surface of a moon made by press-molding and sintering a powder material. This is a stator for an ultrasonic motor.

Typical examples of sintered materials to which the present invention applies include iron-based materials including stainless steel, brass, and copper-based materials including bronze. However, all sintered materials that can be applied to other stators are Targeted.

Low melting point materials are materials with a melting point lower than the melting point of the sintered material itself.
For example, compared to iron-based sintered materials, copper-based, tin-based, and lead-based materials
Furthermore, tin-based and lead-based materials are used in place of copper-based materials. Further, a polymeric material which is a non-metallic material can be used.

The method of infiltrating the sintered material with the low melting point material may be simultaneous infiltration or post-infiltration.

The reason why the infiltration material has a lower melting point than the sintered material is that in the simultaneous infiltration process, the infiltration material melts before the sintered material and is sintered at a higher temperature. After the materials have fused and component diffusion has finished, cooling is performed, and after the sintered material has stabilized,
This is because the infiltrant is stabilized by cooling, and in the post-infiltration process, the infiltrant melts and infiltrates into the pores of the sintered material that has already been sintered, and the sintered material re-fuses. This is to prevent the process of - Simply put, this is to melt and penetrate only the infiltrant into the sintered material without remelting the sintered material.

[Example 1] Materials such as iron-based alloy powder such as 14c r Ni-based stainless steel were used to pressure-form the stator shape and sinter it.

This sintered material was immersed in a molten copper-based material to infiltrate the molten copper-based material into the pores. When the obtained stator was assembled into the ultrasonic motor shown in FIG. 2 and an output test was performed, the results shown in FIG. 1A were obtained.

When the same output test was conducted for the above-mentioned example without the infiltration treatment of the copper-based material, the results shown in Figure 1 were obtained.

Figure 1 shows the fluctuation of the rotation speed when a torque load is applied, with the torque value on the Y-axis and the rotation speed on the Y-axis.When the torque is Okgf-cm, it shows the rotation speed when there is no load. , the torque (load) is gradually increased, and the point where the rotational speed reaches 0 indicates the maximum torque value.

[Effects of the Invention] Although the stator of the present invention is made by sintering, no abrasive grains, cutting fluid, polishing fluid, etc. remain in the holes, so it can be incorporated into an ultrasonic motor. It is possible to eliminate the shortage of the required torque value due to scratches on the contact surface with the rotating body, increased slipperiness, etc. when used in In addition, the life of the turning cutter used during finishing and cutting is shortened because the holes are filled and micro-impacts are less likely to occur. Furthermore, the thermal conductivity improves, improving cooling performance and suppressing temperature rise due to friction when the motor rotates.
The required torque value can be obtained even after continuous operation for a long time.

[Brief explanation of drawings]

FIG. 1 is a graph showing the relationship between rotational speed and torque of an example of the present invention and a comparative example, and FIG. 2 is a sectional view of an example of an ultrasonic motor. ]...Output shaft, 2...Base, 3...Bearing, 4...
... Stator, 5... Rotating body, 6... Belleville spring, 7...
...Piezoelectric element, 8...Case.

Claims (1)

[Claims] A stator for an ultrasonic motor, characterized in that a low melting point material is infiltrated into pores that inevitably occur on the surface of a material obtained by pressure forming and sintering a powder material.