What are the classifications of couplings

Coupling is also called coupling. A mechanical component used to firmly connect the driving shaft and driven shaft in different mechanisms to rotate together and transmit motion and torque. Sometimes it is also used to connect the shaft with other parts (such as gears, pulleys, etc.). It is usually composed of two halves, which are respectively connected with keys or tight fits, fastened on the two shaft ends, and then connected by some way. The coupling can also compensate the offset (including axial offset, radial offset, angular offset or comprehensive offset) between two shafts due to inaccurate manufacturing and installation, deformation or thermal expansion during operation; As well as impact mitigation and vibration absorption.

Most of the commonly used couplings have been standardized or normalized. In general, it is only necessary to correctly select the type of coupling and determine the model and size of the coupling. If necessary, check and calculate the load capacity of vulnerable weak links; When the speed is high, the centrifugal force at the outer edge and the deformation of the elastic element shall be checked, and the balance check shall be carried out.

Couplings can be divided into flexible couplings and rigid couplings.

flexible coupling 

Some of the couplings are flexible and deformable. When two rotating shafts are connected, some misalignment of the two rotating shafts is allowed, that is, dynamic deformable connection. The use of flexible coupling will reduce the accuracy requirements of alignment, facilitate testing, and have a good damping function when the speed is unstable. But it has a disadvantage. Because its materials are rubber, nylon, etc., it has low strength, short life, small bearing capacity, and is not resistant to high and low temperatures. It is only suitable for low temperature occasions.

1. Quincunx coupling

Plum coupling is a widely used coupling, also known as claw coupling, which is composed of two metal claw discs and an elastomer. The two metal jaws are usually 45 steel, but aluminum alloys are also useful when load sensitivity is required. Its elastomer is usually composed of engineering plastics or rubber. The life of the elastomer is the coupling life. The life of the elastomer is 10 years. Elastomer is widely used in the case of strong vibration due to its function of buffering and reducing vibration. The limiting temperature of the elastomer determines the service temperature of the coupling, which is usually - 35 to+80 degrees.

2. Elastic column coupling

The elastic column coupling is a pin made of some non-metallic elastic materials, which is placed in the flange holes of the two coupling halves. Through this pin, two half couplers can be connected. The coupling is simple in structure and easy to manufacture. It is convenient to install, remove and replace the elastic elements without moving the two couplings.

3. Spring coupling

Spring type couplings transmit motion by welding or directly connecting corrugated thin-walled tubes to the two coupling halves. The spring coupling has simple structure, small volume, convenient processing and installation, and high transmission accuracy. They are mainly used for small power precision machinery and control mechanisms that require compact structure and high transmission accuracy.

4. Universal joint coupling

The universal joint coupling makes use of the characteristics of its mechanism, so that two shafts are not on the same shaft, and there is an angle between the shafts. It can realize continuous rotation of two shafts and reliably transmit torque and motion. The biggest feature of universal joint coupling is that its structure has large angle compensation capacity and compact structure, but its transmission efficiency is not very good compared with other couplings. The angle between the two shafts of universal joint couplings of different construction types is different, usually between 5-45.

Rigid coupling

Rigid coupling, as the name implies, is actually a torsional rigid coupling. No turning clearance even under load. The rigid coupling is still rigid to transmit torque even if there is a deviation that generates load. Rigid couplings need to be used to strictly align and connect two shafts without relative misalignment, so they are rarely used in motor test systems. Of course, if the relative displacement can be successfully controlled (the alignment accuracy is high enough), rigid coupling can also play an excellent role in applications. Especially the small size rigid coupling has the advantages of light weight, ultra-low inertia and high sensitivity. In practical application, rigid coupling has the advantages of maintenance free, super oil resistance and corrosion resistance.

Membrane coupling

Several sets of diaphragms (stainless steel plates) are staggered with two half couplings through bolts. Each group of diaphragms consists of several parts, which are divided into connecting rods and whole diaphragms of different shapes. The membrane coupling compensates the relative displacement of the two axes through the elastic deformation of the membrane. It is a high-performance elastic coupling with solid metal elements. It does not need lubrication, has compact structure, high strength, long service life, no rotating clearance, and is not affected by temperature and oil contamination. It has the characteristics of acid resistance, alkali resistance and corrosion resistance, and is suitable for high performance. Shafting transmission has working conditions of temperature, high speed and corrosive medium. In terms of structural features, it has an insurance link. When the actual load exceeds the predetermined load, the diaphragm will break, cutting off the movement and power transmission, thus protecting the rest of the machine from damage and playing a safety role.

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