Coupling is a kind of coupling that connects two shafts or shafts and rotating parts, rotates together in the process of transmitting motion and power, and does not disengage under normal conditionsdevice。Sometimes it is also used as a safety device to prevent the connected parts from bearing excessive loadoverload protectionRole of.
Coupling is also calledCoupling。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 by 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.[1]
Most of the commonly used couplings have been standardized or normalized. Generally, 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, it is also necessary to check the centrifugal force at its outer edge and the deformation of elastic elements, and carry out balance verification.
type
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Couplings can be divided into rigid couplings and flexible couplings.
Rigid couplingIt does not have buffering property and the ability to compensate the relative displacement of two axes, so it is required that the two axes should be strictly aligned. However, this kind of coupling has simple structure, low manufacturing cost, easy assembly, disassembly and maintenance, which can ensure that the two axes have a high alignment, and transmit a large torque, and is widely used.Commonly used areFlange coupling , sleeve coupling and jacket coupling, etc.
Flexible couplingIt can also be divided into flexible couplings without elastic elements and flexible couplings with elastic elements. The former type only has the ability to compensate the relative displacement of two axes, but cannot buffer and reduce vibration. Common types includeSlide coupling、Gear couplingUniversal coupling and chain coupling;Since the latter type contains elastic elements, in addition to the ability to compensate the relative displacement of two axes, it also has the function of buffering and vibration reduction, but the transmitted torque is generally inferior to the flexible coupling without elastic elements due to the limit of the strength of elastic elementsBushed pin type coupling 、elastic pin coupling 、Quincunx coupling、Tire coupling, serpentine spring coupling, reed coupling, etc.[2]
performance requirement
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According to different working conditions, couplings shall have the following performances:
(1) Mobility.The movability of coupling refers to the ability to compensate the relative displacement of two rotating components.Factors such as manufacturing and installation errors between connected components, temperature changes in operation, and deformation under load, all put forward requirements for portability.The movable property compensates or relieves the damage caused by the relative displacement between rotating membersaxis、Bearing, coupling and other components.
(2) Cushioning.For the occasion of frequent load starting or working load change, the coupling shall be equipped with elastic elements for buffering and vibration reduction to protect the prime mover and working machine from less or no damage.
(3) Safe and reliable, with sufficient strength and service life.
(4) Simple structure, easy assembly, disassembly and maintenance.[3]
choice
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When selecting the coupling type, the following items should be considered.
① The size and nature of the torque to be transmitted, the requirements for buffering and damping functions, and whether resonance may occur.
② The relative displacement degree of two shaft axes caused by manufacturing and assembly errors, shaft loading and thermal expansion deformation, and relative movement between components.
③ The allowable overall dimension and installation method shall be the operation space necessary for assembly, adjustment and maintenance.For large couplings, disassembly and assembly shall be possible without axial movement of the shaft.
In addition, the working environment, service life, lubrication, sealing, economy and other conditions should also be considered, and then a suitable coupling type should be selected by referring to the characteristics of various couplings.[4]
