When it comes to selecting the most inconspicuous components in a motor test system, there must be a coupling. The general user will only choose the corresponding size of the coupling according to the shaft diameter of the motor. However, in fact, there are several types of couplings, which should be selected according to different applications in actual use. The classification of couplings is mainly divided into two categories: flexible and rigid
Flexible couplings.
It refers to the part of the coupling that is flexible and deformable, and a certain amount of misalignment of the two shafts is allowed to occur when connecting the shafts on both sides, that is, the coupling that can be deformed under dynamics. When using this type of coupling, it can reduce the accuracy requirements for alignment, facilitate testing, and have a good shock absorption function in the case of unstable speed. But it has a disadvantage, because its material is rubber, nylon, etc., so it has low strength, short life, small bearing capacity, does not resist high and low temperatures, and is only suitable for low temperature occasions.
Torx coupling.
Torx coupling is a very widely used coupling, also known as claw coupling, which is composed of two metal claw discs and an elastomer. The two metal claw discs are generally made of 45 gauge steel, but aluminum alloy is also used when the load is required. Its elastomers are generally composed of engineering plastics or rubber, and the life of the elastomer is the life of the coupling, and the life of the general elastomer is 10 years. Since elastomers have the effect of cushioning and damping vibration, they are often used in occasions with strong vibration. The performance limit temperature of the elastomer determines the operating temperature of the coupling, which is generally -35 to +80 degrees.
Elastic column coupling.
The elastic column coupling is a pin made of a number of non-metallic elastic materials, placed in the flange hole of the two halves of the coupling, and the coupling of the two halves is realized through the pin pin, the coupling is simple in structure, easy to manufacture, and it is more convenient to assemble and disassemble and replace the elastic element, and there is no need to move the two couplings.
Spring-loaded couplings.
Spring-loaded couplings are used to use corrugated thin-walled tubes to directly weld or bond with two halves of couplings to transmit motion. The structure of this coupling is simple, the overall size is small, the processing and installation are convenient, and the transmission accuracy is high, and it is mainly used in the low-power precision machinery and control mechanism that require compact structure and high transmission accuracy.
Universal joint couplings.
The universal coupling uses the characteristics of its mechanism to make the two shafts not on the same axis, and the continuous rotation of the two axes connected can be realized in the case of the angle of the axis, and the torque and motion can be reliably transmitted. The biggest feature of universal coupling is that its structure has a large angular compensation capacity and compact structure, but the transmission efficiency is not very good compared with other couplings. The angle between the two axes of different structural types of universal couplings is different, generally between 5°-45°.
Rigid couplings.
A rigid coupling, as the name suggests, is actually a torsionally rigid coupling, which does not have any slewing backlash even when it is subjected to load, and even when there is a deviation to generate a load, the rigid coupling still rigidly transmits torque. Rigid couplings are required to be used to connect the two shafts to be strictly aligned, and there is no relative misalignment during work, so it is relatively rare in the motor test system. Of course, if the relative displacement can be successfully controlled (with a sufficiently high degree of alignment), rigid couplings can also perform very well in the application. In particular, the small rigid coupling has the superior performance of light weight, ultra-low inertia and high sensitivity, and in practical application, the rigid coupling has the advantages of maintenance-free, super oil resistance and corrosion resistance.
Diaphragm couplings.
It consists of several groups of diaphragms (stainless steel sheets) staggered with bolts and two halves of couplings, and each group of diaphragms is composed of several stacked pieces, and the diaphragms are divided into connecting rod type and whole piece type of different shapes. The diaphragm coupling relies on the elastic deformation of the diaphragm to compensate for the relative displacement of the two shafts, which is a high-performance metal strong element flexible coupling, without oiling, compact structure, high strength, long service life, no rotation clearance, not affected by temperature and oil pollution, with the characteristics of acid resistance, alkali resistance and anti-corrosion, suitable for shaft transmission at high temperature, high speed and corrosive medium working conditions. And in its structural characteristics, it has an insurance link, when the actual load exceeds the load limited in advance, the diaphragm will break, cut off the transmission of motion and power, so as to protect the rest of the machine from damage, play a role in safety protection.
Flange. Flange, also known as protruding edge. A flange is a part that is connected to each other between shafts. Flange connection or flange joint refers to the detachable connection of flanges, gaskets and bolts connected to each other as a group of combined sealing structures, which is often used in the occasion of large torque transmission.
Summary. In practical application, if it is only an ordinary motor performance test, considering the problem of alignment accuracy and test installation speed, using a flexible coupling is a more convenient and fast choice; However, for the dynamic characteristics test of the motor, when it is necessary to pay attention to the transient torque output characteristics of the motor, it is better to choose a rigid coupling that can fully reflect the torque transmission process.