What Is Harmonic Motion?
Harmonic transmission uses a constructed and controlled elastic deformation to realize the transmission of mechanical motion.
Harmonic drive
Right!
- Chinese name
- Harmonic drive
- Foreign name
- Harmonic drive
- Single stage
- 50-300
- Bipolar
- Up to 2 × 10 ^ 6
- Related
- Harmonic transmission uses a constructed and controlled elastic deformation to realize the transmission of mechanical motion.
- Harmonic transmission is achieved using a constructed and controlled elastic deformation
- Mechanical transmission consisting of three basic components: wave generator, flexible part and rigid part. This transmission is under the action of a wave generator,
- Harmonic drive
- Figure 2 shows that a flexible wheel with many teeth (more than 120) on the outer periphery meshes with a rigid wheel with teeth on the inner periphery for transmission. Assuming that the number of teeth increases infinitely and the tooth height also decreases infinitely, it becomes a harmonic friction transmission where the outer surface of the flexible wheel and the inner surface of the rigid wheel make contact in the long axis direction of the wave generator. Because the friction at this contact point is small, the transmitted torque is not large, and it is easy to slip. In fact, it is rarely used. Harmonic transmission can also be designed to change from rotation to linear motion to become a harmonic helical transmission. Harmonic gear transmission is the most widely used among the three transmissions. The wave generator in Figure 2 is a mechanical wave generator, in addition to electromagnetic, hydraulic and pneumatic wave generators, of which the mechanical wave generator is the most common.
- Harmonic transmission is a patent filed by American CW Mather in 1955, approved in 1959, and exhibited in New York in 1960. The development of harmonic transmission was started by military and cutting-edge technology, and gradually expanded to civilian and general machinery in the future. Some countries, such as the United States, Japan, and the Soviet Union, already have a series of products for harmonic gear reducers, and China has also formulated ministerial standards for harmonic gears.
- The working principle is based on harmonic gear drive as an example. It uses the relative motion of the flexible wheel, the rigid wheel and the wave generator, especially the controllable elastic deformation (shape change) of the flexible wheel to realize the motion and power transmission. One of these three basic components can be fixed arbitrarily, and the remaining one is a driving member and one is a driven member. If none of them is fixed, it becomes a differential gear train. If the rigid wheel is fixed, the wave generator is used as the driving part, and the flexible wheel is used as the driven part. The oval cam in the wave generator rotates in the flexible wheel to deform the flexible wheel. When the flexible gear teeth and the rigid gear teeth of the two ends of the long axis of the elliptical cam of the wave generator come into engagement, the flexible gear teeth at the two ends of the short shaft are disengaged from the rigid gear teeth. For the teeth between the long axis and the short axis of the wave generator, the different segments along the circumference of the flexible wheel and the rigid wheel are in a semi-engaged state that gradually enters the engagement, which is called a meshing state; It is called gnawing out. The continuous rotation of the wave generator causes the four movements of engaging, engaging, engaging and disengaging to continuously change their original working conditions. This type of movement is called staggered movement. Staggered motion changes input rotation into output movement. If the rigid wheel is fixed, the flexible wheel rotates in the opposite direction relative to the wave generator. Conversely, if the flexible wheel is fixed, the rigid wheel rotates in the same direction relative to the wave generator. For the harmonic gear transmission of double wave transmission, its rotation rule is: the wave generator makes one revolution, and the flexible wheel rotates through the arc length of the two tooth pitches in the circumferential direction relative to the rigid wheel. The rotation ratio is calculated as follows:
- When the wheel is fixed
- formula
- formula
- Structure The structure of the harmonic gear transmission has various types. Figure 3 shows the structure of the single-stage dual-wave harmonic gear reducer.
- Harmonic drive
- Harmonic reducer
- Flexible wheel: thin-walled cup-shaped, thin-walled cylindrical or flat-embedded. A ring gear is formed on the outside of the open end of the thin-walled cylindrical flexible wheel, which deforms with the rotation of the wave generator, and the bottom part of the cylinder is connected with the output shaft.
- rigid wheel: it is a rigid internal gear. Double-wave harmonically driven rigid wheels usually have two teeth more than flexible wheels. Harmonic gear reducers are mostly fixed with rigid wheels, and the outside is connected to the box.
- Two or more single-stage harmonic gear reducers are connected in series to form a compound harmonic gear reducer with a transmission ratio of 106
- Harmonic drive
- The characteristics of harmonic drive are:
- The transmission ratio is large, and the selection range is wide. Single-stage harmonic gears generally have a transmission ratio of 60 to 320, with 80 to 200 being the most commonly used.
- The number of teeth that are meshed at the same time when transmitting torque is large. Generally, the number of meshing teeth of double-wave transmission can account for about 30% of the total number of teeth, and three-wave transmission is more. Therefore, the contact between the transmission wheels is surface contact, and the specific pressure on the tooth surface is small, so the bearing capacity is high.
- The reducer composed of harmonic gears is light in weight and small in size, and the transmission device contains fewer parts.
- Smooth transmission and low noise.
- High transmission efficiency.
- The movement accuracy is high. When starting or reversing, the output shaft will follow instantly, and there is no lost motion, and it can realize zero hysteresis rotation.
- Radon can form a sealed transmission, so it can transfer motion in the environment of high temperature, high pressure, high vacuum, harmful gas or atomic energy radiation.
- The output and input shafts are on the same axis.
- Easy maintenance, easy maintenance, inspection and replacement parts. Harmonic gear transmission can be used in the follow-up systems of radars, aircrafts, manipulators, artificial limbs, etc. It can also be used in the fine-tuning mechanism of reduction gears and instruments in lifting and transportation, chemical machinery, printing machinery, power tools.