Views:16 Author:xia Publish Time: 2020-08-11 Origin:Site
A classical gear type, the dentate part is parallel to the central axis. The dentate concave part is not upright(slightly curved). This design can reduce the speed and torque between the gears when meshing each other, increase utilization power.
In realistic applications, due to stable transmission, low impact, vibration, and noise, helical gear is widely used in high speed and heavy-duty load. Helical is not entirely spiral. Spiral gears are the two helical gear meshing, which distinguished by the direction of transmitting force in spatial. Common straight gear along the tooth width enters into meshing, which results in impact and vibration noise. The transmission is not stable. Helical cylindrical gear is superior to straight gear and can be used in high speed and heavy load.
Double Helical Gear
A helical gear has lateral force on its shaft. To eliminate this force, gear is made a helical gear in the opposite direction of symmetry, which looks like a personal character. The herringbone gear has the advantage of small axis load, high bearing capacity, and stable operation. The processing of herringbone gear is complicated, which can be processed by the development method. However, the hobbing method can not process all herringbone gears. The milling method which has great difficulty is relatively common.
The bevel gear is used for transmission between intersecting shaft. Compared with cylindrical gear, it can change the transmission direction. The single-stage transmission ratio can reach up to 6. Spur gear and helical gear are simple in the design, manufacture, and installation, but their noise is huge and used for transmission at low speed(< 5m/s). The transmission power of spur gear and helical gear can reach up to 370kw, circular speed is 5m/s speed. Helical gear and bevel gear has a stable transmission, high bearing capacity. But the manufacture is difficulty and the application is less. The curve tooth bevel gear transmission runs smoothly, and transmission power can reach up to 3700 kilowatts. The circular speed can reach up to 40 m/s. The bevel gear can be divided into straight bevel gear, spiral bevel gear, and so on.
Spiral Bevel Gear
It is often used for motion and power transmission between two intersecting axes. The teeth of spiral bevel gear are distributed on the surface and the tooth profile decreases gradually form a big end to the small end. The tooth profile is an arc shape. The spiral bevel gear has high transmission efficiency, stable transmission ratio, large arc overlap coefficient, high bearing capacity, compact structure, energy-saving, space-saving, abrasion resistance, long life, low noise. Among all kinds of mechanical transmission, the transmission efficiency of spiral bevel gear is the highest, which has great economic benefits for all kinds of transmission, especially for high power transmission.
The worm gear worm mechanism is often used to transfer the motion and power. Worm gear and worm are similar to gear and rack in the middle plane. If you want to get a relatively high gear ratio, the worm gear should be used. The gear ratio of worm is relatively 20:1, some can up to 300:1. the worm gear has an interesting characteristic that other gear types don’t have: the worm can turn the gear easily, but the gear can not turn the worm. This is because the spur gear on the screw is shallow. When the gear tries to turn the worm, the friction between the gear and worm will keep the screw in place.
The gear on the inner circle is internal gear, which usually in the inner meshing gear mechanism.
The Gear and Rack
In the process of transmission, the gear and rack have its unique motion characteristic: the gear transmission is used for transmitting the motion and power between any two axes. The circle speed can reach up to 300 m/s, the transmission power can reach up to 105kw. The diameter of gear ranges from 1mm to 150m, which is a widely used mechanical transmission.
Compared with belt-drive, it has the following advantage:
Long life, stable operation, high reliability
Guarantee constant transmission ratio, and transmit the motion between two axes at any included angle.