Many types of actuators driven by the frictional force have been developed for the use of the linear or rotation motor by many researchers in Japan, USA, EU and etc. There are several advantages as following : stable operation with low velocity and high torque, which is suited for direct drive; quic...
Many types of actuators driven by the frictional force have been developed for the use of the linear or rotation motor by many researchers in Japan, USA, EU and etc. There are several advantages as following : stable operation with low velocity and high torque, which is suited for direct drive; quick response and excellent controllability of starting, stopping and reversing; small size and light; no electromagnetic disturbances. The converting of the mechanical vibrations of the piezoelectric ceramics into the linear motion of the object, in usual, can be realized by producing an elliptical trajectory from an contact interface between two materials. These kinds of conventional ultrasonic linear motors, however, have the limitations of down-sizing and lightweight for adapting to the mobile communication handsets. In this study, the principle of operating of a tiny ultrasonic linear motor driven the frictional force is newly proposed. Then the properties of the frictional materials for the use of shaft and mobile are intensively investigated in addition to considering the dynamic properties of the ultrasonic motor. The results of the present study are summarized as follows. 1. The novel principle for operating the ultrasonic motor was derived by utilizing the piezoelectricity of the piezoelectric ceramics and Newton's law of the motion of the object, so called inertia. The fringe of the actuating part which is consisted of elastic material and one(uni-morph) or two ceramics(bi-morph) with the radial mode was fixed on the rigid body, and when the saw tooth electrical potential was applied to the piezoelectric ceramics, the vibration was converted from radial mode of the piezoelectric ceramics into up-and-down movement of the actuating part. At this time, if the shaft with a mobile pressed with a certain force was located on the center of the actuating part, when the vibration of the up-and-down was generated, the frictional force and inertia were induced at the interface between the shaft and mobile. 2. The modal and harmonic analysis were carried out using the simulation program(ATILA5.2.1) of the finite element method. As a result, the coupling coefficient and the total displacement of the piezoelectric ceramics itself were 39% and 1.38x10-8(m) at the resonance frequency of 693(kHz). In the case of the actuator which has the bi-morph type with the elastic material and shaft, the coupling coefficient was 24% at 25(kHz). 3. For the purpose of investigating the frictional property, the DLC and PTFE coated stainless steel, no coated stainless steel and Pyrex were prepared for the use of shaft material, and bakelite and stainless steel substrate for mobile material. The frictional coefficient of DLC coated was shown the lowest value regardless of the substrate(either bakelite or stainless steel), but the frictional coefficients of the others were increased so far 0.56 to 0.71 when the substrate was changed from bakelite to stainless steel. The static friction force was dependent on the tensile speed and the compressive force of the shaft 4. When the stainless steel was used for the mobile, Pyrex shaft was shown not only the high velocity but also high thrust force(12~14mm/sec, 20g). In the test of the shaft displacement property with no mobile, the actuators with the stainless steel and Pyrex shaft were shown the high velocity(468mm/sec, 394mm/sec) and high displacement, but DLC was shown the lowest velocity and the smallest displacement. 5. It was found that the trust force of shaft, which made of different materials such as DLC or PTFE coated stainless, no coated stainless steel and Pyrex, varied remarkably relative to the increasing of the compressive force producing a frictional force. In particular, the significant increase of the thrust force was measured between the Pyrex shaft and the stainless steel mobile. 6. In this study, shafts made of DLC and PFTE coated stainless steel, uncoated stainless steel and Pyrex, and mobile elements made of bakelite and stainless steel, were used. We investigated the changes in the frictional coefficients by means of the frictional test and found that the optimal shaft/mobile couplings were stainless steel shaft/stainless steel mobile and Pyrex shaft/stainless steel mobile in a novel tiny ultrasonic linear motor driven by the new principle and the frictional force between the shaft and the mobile element.
Many types of actuators driven by the frictional force have been developed for the use of the linear or rotation motor by many researchers in Japan, USA, EU and etc. There are several advantages as following : stable operation with low velocity and high torque, which is suited for direct drive; quick response and excellent controllability of starting, stopping and reversing; small size and light; no electromagnetic disturbances. The converting of the mechanical vibrations of the piezoelectric ceramics into the linear motion of the object, in usual, can be realized by producing an elliptical trajectory from an contact interface between two materials. These kinds of conventional ultrasonic linear motors, however, have the limitations of down-sizing and lightweight for adapting to the mobile communication handsets. In this study, the principle of operating of a tiny ultrasonic linear motor driven the frictional force is newly proposed. Then the properties of the frictional materials for the use of shaft and mobile are intensively investigated in addition to considering the dynamic properties of the ultrasonic motor. The results of the present study are summarized as follows. 1. The novel principle for operating the ultrasonic motor was derived by utilizing the piezoelectricity of the piezoelectric ceramics and Newton's law of the motion of the object, so called inertia. The fringe of the actuating part which is consisted of elastic material and one(uni-morph) or two ceramics(bi-morph) with the radial mode was fixed on the rigid body, and when the saw tooth electrical potential was applied to the piezoelectric ceramics, the vibration was converted from radial mode of the piezoelectric ceramics into up-and-down movement of the actuating part. At this time, if the shaft with a mobile pressed with a certain force was located on the center of the actuating part, when the vibration of the up-and-down was generated, the frictional force and inertia were induced at the interface between the shaft and mobile. 2. The modal and harmonic analysis were carried out using the simulation program(ATILA5.2.1) of the finite element method. As a result, the coupling coefficient and the total displacement of the piezoelectric ceramics itself were 39% and 1.38x10-8(m) at the resonance frequency of 693(kHz). In the case of the actuator which has the bi-morph type with the elastic material and shaft, the coupling coefficient was 24% at 25(kHz). 3. For the purpose of investigating the frictional property, the DLC and PTFE coated stainless steel, no coated stainless steel and Pyrex were prepared for the use of shaft material, and bakelite and stainless steel substrate for mobile material. The frictional coefficient of DLC coated was shown the lowest value regardless of the substrate(either bakelite or stainless steel), but the frictional coefficients of the others were increased so far 0.56 to 0.71 when the substrate was changed from bakelite to stainless steel. The static friction force was dependent on the tensile speed and the compressive force of the shaft 4. When the stainless steel was used for the mobile, Pyrex shaft was shown not only the high velocity but also high thrust force(12~14mm/sec, 20g). In the test of the shaft displacement property with no mobile, the actuators with the stainless steel and Pyrex shaft were shown the high velocity(468mm/sec, 394mm/sec) and high displacement, but DLC was shown the lowest velocity and the smallest displacement. 5. It was found that the trust force of shaft, which made of different materials such as DLC or PTFE coated stainless, no coated stainless steel and Pyrex, varied remarkably relative to the increasing of the compressive force producing a frictional force. In particular, the significant increase of the thrust force was measured between the Pyrex shaft and the stainless steel mobile. 6. In this study, shafts made of DLC and PFTE coated stainless steel, uncoated stainless steel and Pyrex, and mobile elements made of bakelite and stainless steel, were used. We investigated the changes in the frictional coefficients by means of the frictional test and found that the optimal shaft/mobile couplings were stainless steel shaft/stainless steel mobile and Pyrex shaft/stainless steel mobile in a novel tiny ultrasonic linear motor driven by the new principle and the frictional force between the shaft and the mobile element.
주제어
#재료 공학[材料工學]
※ AI-Helper는 부적절한 답변을 할 수 있습니다.