Robot Special Reducer Manufacturer:Japan Harmonic Drive
1.Harmonic gear drive definition
Mainly composed of four basic components: wave generator, flexible gear, flexible bearing, and rigid gear. Harmonic drive reducer is a kind of flexible gear that is equipped with a flexible bearing to make the flexible gear produce controllable elastic deformation. , And meshed with rigid gears to transmit motion and power gear transmission. Applied disciplines: mechanical engineering (first-level discipline); transmission (second-level discipline); gear transmission (third-level discipline) Harmonic gear transmission reducer is a new type of reducer developed using the principle of planetary gear transmission. Harmonic gear drive (referred to as harmonic drive).
It mainly consists of three basic components:
(1) Rigid gear (rigid wheel) with internal ring gear;
(2) Flexible gear (flexible gear) with outer ring gear;
(3) Wave generator H.
As a reducer, it usually adopts active wave generator, fixed rigid wheel, and output form of flexible wheel.
2.Characteristics of Harmonic Drive Reducer
The wave generator H is a rod-shaped component, the two ends of which are equipped with rolling bearings to form rollers, and are pressed against the inner wall of the flexspline 1. The flexspline is a thin-walled gear that can produce greater elastic deformation, and its inner hole diameter is slightly smaller than the total length of the wave generator. The wave generator is a component that makes the flexible wheel produce controllable elastic deformation. When the wave generator is installed in the flexspline, the cross-section of the flexspline is forced to change from the original circular shape to an ellipse. The teeth near the two ends of the long axis are completely meshed with the teeth of the rigid wheel, while the teeth near the ends of the short axis are Completely disengaged from the Gang wheel. The teeth of other sections on the circumference are in a transitional state of meshing and disengaging. When the wave generator continuously rotates in the direction shown in the figure, the deformation of the flexspline is constantly changing, so that the meshing state of the flexspline and the rigid wheel is also constantly changing, from engagement, engagement, engagement, engagement, disengagement, and re-engagement…, It goes round and round, so as to realize the slow rotation of the flexible wheel relative to the rigid wheel in the opposite direction of the wave generator H. When working, the rigid wheel is fixed, the motor drives the wave generator to rotate, and the flexible wheel acts as a driven wheel to output rotation and drive the load to move. In the transmission process, the wave generator makes one revolution and the number of cycles of deformation at a certain point on the flexspline is called the wave number, which is represented by n. Commonly used are two-wave and three-wave. The flexspline of the double-wave transmission has less stress and a relatively simple structure, which makes it easy to obtain a large transmission ratio. Therefore, it is the most widely used one.
The tooth pitch of the flexible wheel and rigid wheel of harmonic gear transmission is the same, but the number of teeth is not equal. Usually, the difference between the number of teeth of the rigid wheel and the flexible wheel is equal to the wave number, that is
z2-z1=n
In the formula, z2 and z1–respectively the number of teeth of rigid wheel and flexible wheel.
When the rigid wheel is fixed, the generator is active, and the flexible wheel is driven, the transmission ratio of the harmonic gear drive is
i=-z1/(z2-z1)
In double-wave transmission, z2-z1=2, and there are many flexspline teeth. The minus sign in the above formula means that the steering of the flexspline is opposite to that of the wave generator. It can be seen that the harmonic reducer can obtain a large transmission ratio.
3.Basic feature of Harmonic Drive Reducer
(1)High load-carrying capacity In harmonic transmission, the tooth-to-tooth meshing is in surface contact, and the number of simultaneous meshing teeth (overlap coefficient) is relatively large, so the load per unit area is small and the load-bearing capacity is higher than other transmission forms.
(2)Large transmission ratio The transmission ratio of single-stage harmonic gear transmission can reach i=70~500.
(3)Small size and light weight.
(4)High transmission efficiency and long life.
(5)Smooth transmission, no impact, no noise, and high movement precision.
(6)Because the flexspline bears a large alternating load, the fatigue strength, processing and heat treatment requirements of the flexspline material are relatively high, and the process is complicated.
Harmonic reducer was developed only in the 1960s and 1970s in China, and many manufacturers have specialized in production and formed serialization. It is widely used in electronics, aerospace, robotics and other industries. Due to its unique advantages, its applications in the chemical industry are gradually increasing.
4.Model series of Harmonic Drive Reducer
Cup type series harmonic drive reducer
Cap type series harmonic drive reducer
Ultra-thin series harmonic drive reducer
High torque type series harmonic drive reducer
5.Main advantages of Harmonic Drive Reducer
(1) The transmission speed ratio is large. The single-stage harmonic gear transmission speed ratio ranges from 70 to 320, in some devices it can reach 1000, and the multi-stage transmission speed ratio can reach more than 30,000. It can be used not only for deceleration, but also for speed-increasing occasions.
(2) High carrying capacity. This is because the number of teeth meshed at the same time in the harmonic gear drive is large, and the number of teeth meshed at the same time in the double-wave drive can reach more than 30% of the total number of teeth. Moreover, the flexspline uses high-strength materials, and the teeth and teeth are in surface contact.
(3) High transmission accuracy. This is because the number of teeth meshed at the same time in the harmonic gear transmission is large, and the error is averaged, that is, the multi-tooth meshing has a mutual compensation effect on the error, so the transmission accuracy is high. In the case of the same gear accuracy grade, the transmission error is only about 1/4 of that of ordinary cylindrical gear transmission. At the same time, the radius of the wave generator can be changed slightly to increase the deformation of the flexspline so that the backlash is small, and even the backlash-free meshing can be achieved, so the harmonic gear reducer has a small idle stroke and is suitable for reverse rotation.
(4) High transmission efficiency and smooth movement. Due to the uniform radial movement of the flexspline gear teeth during the transmission process, even if the input speed is high, the relative slip speed of the gear teeth is still extremely low (so it is one percent of the ordinary involute gear transmission) Therefore, the gear teeth are less worn and the efficiency is high (up to 69%~96%). Also, since both sides of the gear are engaged in work when engaging in and out, there is no impact phenomenon and the movement is stable.
(5) The structure is simple, the number of parts is small, and the installation is convenient. There are only three basic components, and the input and output shafts are coaxial, so the structure is simple and the installation is convenient.
(6) Small size and light weight. Compared with the general reducer, when the output torque is the same, the volume of the harmonic gear reducer can be reduced by 2/3, and the weight can be reduced by 1/2.
(7) Motion can be transmitted to the confined space. Using the flexible characteristics of the flexspline, this valuable advantage of the wheel drive is unmatched by other existing drives.
6.Application range of Harmonic Drive Reducer
Harmonic gear reducers are used in aviation, aerospace, energy, navigation, shipbuilding, bionic machinery, commonly used ordnance, machine tools, instruments, electronic equipment, mining and metallurgy, transportation, lifting machinery, petrochemical machinery, textile machinery, agricultural machinery and medical treatment Apparatus and other aspects are increasingly widely used, especially in the servo system with high dynamic performance, the use of harmonic gear transmission shows its superiority. The power it transmits ranges from tens of watts to tens of kilowatts, but high-power harmonic gear drives are mostly used in short-term workplaces.
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