(XNUMX) Allowable speed of coupling

The allowable speed range of the coupling is determined by calculation based on the allowable linear speed and maximum outer edge size of different materials of the coupling.The allowable speed range of couplings of different materials, varieties and specifications is different. Changing the material of the coupling can increase the allowable speed range of the coupling. The allowable speed for steel is greater than the allowable speed for cast iron.

For couplings used under working conditions of n>5000r/min, influencing factors such as the centrifugal force on the outer edge of the coupling and the deformation of elastic elements should be considered, and should be dynamically balanced.Non-metallic elastic element elastic couplings should not be used at high speeds. When the elastic elements are deformed at high speeds, high-precision flexible couplings should be selected. At present, the couplings used for high-speed abroad are nothing more than diaphragm couplings and High-precision drum gear coupling.

(XNUMX) Relative displacement of the two shafts connected by the coupling

The two shafts connected by the coupling are deformed due to manufacturing errors, assembly errors, installation errors, shaft load, base deformation, bearing damage, temperature changes (thermal expansion, cold contraction), relative movement between components, etc. This kind of factor produces relative displacement.Under normal circumstances, the relative displacement of the two shafts is unavoidable, but the displacement direction generated by the shafting transmission under different working conditions, namely axial (x), radial (y), angular (α) and displacement The size varies.Only the flexible coupling has the performance of compensating the relative displacement of the two shafts. Therefore, a large number of flexible couplings are selected in practical applications.Rigid couplings do not have compensation performance and their application range is limited, so the amount used is small.The only larger shafting transmission in the angular direction (α) should be a universal coupling. For shafting transmissions that have axial movement and need to control the axial displacement, a diaphragm coupling should be used; only the alignment accuracy is very high. The rigid coupling is selected in the case of high, and the allowable compensation amount of each standard flexible coupling is shown in Table 3.

(XNUMX) Transmission accuracy of the coupling

The shafting transmission with small torque and mainly transmitting motion requires the coupling to have high transmission accuracy, and a flexible coupling with a metal elastic element should be used.The shaft transmission with large torque and power transmission also has requirements for transmission accuracy. At high speeds, avoid the use of non-metal elastic elements, flexible couplings and flexible components with gaps between the movable elements; couplings are suitable Choose a diaphragm coupling with high transmission accuracy.

(XNUMX) Coupling size, installation and maintenance

The outer dimensions of the coupling, that is, the maximum radial and axial dimensions, must be within the installation space allowed by the machine and equipment.Should choose a coupling that is convenient for assembly and disassembly, does not require maintenance, has a long maintenance period or is convenient for maintenance, does not need to move the two shafts to replace the wearing parts, and is easy to adjust the middle.

It is difficult to adjust the alignment of the two shafts of large machinery and equipment, so you should choose the coupling that is durable and easy to replace the wearing parts.Flexible couplings with metal elastic elements generally have a longer service life than flexible couplings with non-metal elastic elements.The need for sealing and lubrication and the use of non-durable couplings will inevitably increase maintenance workload.For occasions with long-term continuous operation and high economic benefits, such as the high-speed end of the rolling mill transmission system of my country's metallurgical enterprises, gear couplings are currently commonly used. Although gear couplings theoretically transmit large torque, they must It can work for a long time under the condition of good lubrication and sealing, and the sealing condition needs to be checked frequently. Notelubricating oilOr lubricating grease, the maintenance workload is large, the auxiliary working hours are increased, the effective working time is reduced, and the production efficiency is affected.In developed countries in the world, diaphragm couplings with long service life, no lubrication and maintenance have been widely used to replace drum-shaped gear couplings, which not only improve economic efficiency, but also purify the working environment.In the rolling mill transmission system, the flexible movable pin coupling and the sector-shaped elastic coupling developed by me are used, which not only has the advantages of the diaphragm coupling, but also has a good cushioning effect and a low price.

(XNUMX) Working environment

Couplings are used in conjunction with various host products, and the surrounding working environment is more complicated, such as temperature, humidity, water, steam, dust, sand, oil, acid, alkali, corrosive media, salt water, radiation and other conditions. One of the important factors that must be considered when shafting.For the working environment with high temperature, low temperature, oil, acid and alkali medium, it is not suitable to choose flexible couplings with general rubber as the elastic element material, but should choose flexible couplings with metal elastic elements, such as diaphragm couplings, Serpentine spring couplings, etc.

The elastic pin coupling has high noise due to the movement of the pin during operation, so it should not be used in occasions with strict requirements for noise.

 

Table 3 Allowable compensation amount of flexible coupling and elastic coupling 

Due to the different types, types and specifications of the coupling structure, material, size and accuracy, the cost and manufacturing cost vary greatly.The cost of couplings with general accuracy requirements is lower than that of high-precision couplings; the cost of couplings with simple structure and good manufacturability is lower than that of couplings with complex structure and poor manufacturability; couplings that use general materials as raw materials The cost is lower than that of couplings using special materials as raw materials; the cost of flexible couplings with non-metal elastic elements is lower than that of flexible couplings with metal elastic elements.When choosing a coupling, price is an important factor that cannot be ignored, and sometimes it is even a decisive factor.For general working conditions, there is no need to choose more expensive high-precision couplings. For economic reasons, users often cannot choose some flexible couplings with good performance but higher prices.

When selecting a coupling, it is necessary to consider the various factors mentioned above in accordance with the actual conditions and requirements of the selection, and select the coupling variety, type and specification that best suits your needs from the existing standard couplings.Under normal circumstances, the existing standard coupling can basically meet the needs of different working conditions.