Transmission machinery design requirements | transmission machinery types | transmission machinery performance characteristics

 What is the transmission machinery?Answer, it is a kind of mechanical device with transmission function, which uses mechanical means to transmit power and movement.Below, the editor will introduce the design requirements, types and related performance characteristics of the transmission machinery.

Transmission machinery design requirements

Two-dimensional AutoCAD is commonly used. If you are engaged in machinery, it is recommended to use CAXA (version 2007R3 Enterprise Edition); for modeling, use Pro/E or Solidworks. First draw a two-dimensional drawing and then use a three-dimensional software to draw each part, and finally assemble it. Simulation The above two three-dimensional software can be simulated.Mechanical transmission is widely used in mechanical engineering, mainly refers to the transmission of power and movement by mechanical means.

Transmission machinery type

Divided into two categories:

One is to rely on the friction between the parts to transmit power and friction transmission.

The second is the meshing transmission that relies on the meshing of the driving member and the driven member or the meshing of the intermediate member to transmit power or movement.

Transmission mechanical performance characteristics

Belt drive:

1) Flat belt drive:
a) The structure is simple, the center distance that can be transmitted is large, and there is no vibration in the transmission
b) The sliding coefficient is large, and the transmission power is small
2) V-belt drive:
a) The sliding coefficient is smaller than that of the flat belt drive, the transmission power is larger (multiple belts are used in combination), and there is no vibration during the transmission
b) The friction is large, and the pulley processing is more difficult than the flat pulley

* In the case of V-belt transmission, because the diameter of each point on the belt section is different (D, d1, d2), the rotation speed of each point is different, and the belt itself is a whole, so the upper and lower parts of the belt are opposite to the groove of the pulley Slipping in the direction will cause greater friction and easily generate heat due to friction.

* Since the circumference of the V-belt is standard and fixed, the standard V-belt cannot be used for the belt drive with non-standard center distance. At this time, the "active V-belt" can be used. This type of belt has the same cross-section as the standard belt, but it It is fastened by small pieces of connecting pieces with screws, so in use, the connecting pieces can be arbitrarily increased or reduced according to the required length.The power of this type of belt drive is smaller than the standard V-belt of the same specification.

Chain drive:

1) Can guarantee accurate average speed ratio
2) It can transmit power and movement between two axles with a large center distance
3) The chain is easy to wear, and the chain pitch after wear is increased, and the chain is easy to fall off
4) The speed of chain transmission is low, and there is noise during operation

gear drive:

1) The moving speed of the transmission is faster than that of the bushing chain, and the noise during operation is lower than that of the bushing chain. It is a form of high-speed chain transmission.
2) The requirements for the sprocket material and heat treatment are high, because the toothed chain exerts greater pressure and friction on the sprocket circumferential surface, which is easy to cause wear.

Worm drive:

1) Since the worm is equivalent to a screw, when the lead angle of the worm is smaller than the friction angle, the worm drive is self-locking. At this time, the worm gear can only be driven by the worm, but not by the worm.
2) The structure of the worm gear pair transmission is compact, and the outer dimension of the turbine box is small.
3) The worm gear pair has a smooth transmission and no noise
4) The transmission of worm gear pair is sliding friction, and the friction damage in the transmission is relatively large, so the transmission efficiency is low.When using self-locking worm drive, the efficiency is about 50%.
5) When the worm is driven, the movement speed between the worm and the worm wheel teeth is large, and the friction is also large. In order to improve the life of the worm gear transmission, the worm is generally made of steel, and the worm wheel is made of wear-resistant materials such as bronze.

Thread (screw) transmission:

It can convert a small rotational torque into a large axial force.
High transmission accuracy can be achieved, and the angle of rotation can be converted into a more accurate linear movement distance.
The threaded drive works smoothly and is easy to self-lock.
The structure is simple and the manufacturing is convenient.
The disadvantage is that the friction loss is large and the transmission efficiency is low.

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