Do You Know The Basics Of Diaphragm Coupling?

The structure of diaphragm coupling

Diaphragm coupling is a metal flexible coupling. It is a transmission device that uses metal elastic diaphragm as a flexible element to transmit torque. Its main features are: large torque transmission capacity, absorbing unit misalignment by diaphragm deformation, no relative movement between parts, no wear, no noise, long vibration reduction life, and no need for lubrication. The torsional stiffness and critical speed can be adjusted by changing the outer diameter or wall thickness of the intermediate section, thereby improving the torsional vibration characteristics of the unit.

The diaphragm coupling consists of at least one diaphragm and two sleeves. The diaphragm is fastened to the sleeve with a pin and generally does not loosen or cause backlash between the diaphragm and the sleeve. Some manufacturers offer two diaphragms, and some offer three diaphragms, with one or two rigid elements in the middle and the two sides connected to the sleeves. The difference between single diaphragm coupling and double diaphragm coupling is the ability to handle various deviations. Since it requires the diaphragm to be able to bend in complex directions, single diaphragm couplings are not very suitable for eccentricity. Double diaphragm couplings can bend in different directions at the same time to compensate for eccentricity.

Main characteristics of diaphragm couplings

(1) It has a strong ability to compensate for the misalignment of the two axes. Compared with the gear coupling, the angular displacement can be twice as large. The reaction force during radial displacement is small, the flexibility is large, and a certain axial, radial and angular displacement is allowed.
(2) It has obvious shock absorption effect, no noise, and no wear.
(3) It can adapt to high temperature (-80+300) and harsh environment, and can operate safely under impact and vibration conditions.
(4) The transmission efficiency is high, up to 99.86%. It is particularly suitable for medium and high speed high power transmission.
(5) It has a simple structure, light weight, small size, and easy installation and disassembly. It can be installed and disassembled without moving the machine (referring to the type with intermediate shaft), and no lubrication is required.
(6) It can accurately transmit the speed, run without slip, and can be used for the transmission of precision machinery.

The currently known diaphragm coupling can produce a maximum coupling transmission power of 50,000kw, a maximum speed of 80,000rpm, and a maximum length of 12 meters. In addition, the diaphragm coupling can be modified in many ways. As shown in the following figure:

Application of diaphragm coupling

Diaphragm couplings are widely used in shaft transmission of various mechanical devices, such as water pumps (especially high-power and chemical pumps), fans, compressors, hydraulic machinery, petroleum machinery, printing machinery, textile machinery, chemical machinery, mining machinery, metallurgical machinery, aviation (helicopters), ship high-speed power transmission systems, steam turbines, piston power mechanical transmission systems, tracked vehicles, and high-speed and high-power mechanical transmission systems of generator sets. It is common to use diaphragm couplings in high-speed transmission shaft systems after dynamic balancing.

Causes of abnormal noise of diaphragm coupling

(1) The gap between the two halves of the coupling is too wide, causing the diaphragm to be subjected to a large axial force, causing the twisting hole or twisting bolt to wear, resulting in abnormal sound;
(2) The axial offset or deflection angle of the two halves of the coupling is too large, which will also cause vibration and abnormal sound when the equipment is running;
(3) When there is a speed difference between the active end and the passive end, it will also cause vibration and abnormal sound when the equipment is running;
(4) The speed encoder of the motor fails, causing the motor speed to be fast and slow, causing abnormal sound of the diaphragm coupling.