Coupling selection method

Couplings variety, type, specifications a lot, in the correct understanding of variety, type, size, based on the concept of their own, according to the needs of the transmission to select the coupling, the first standard has been developed from the choice of coupling, The development of the international and the subject of dozens of standard coupling, the standard coupling the vast majority of general-purpose coupling, universal coupling notching machine, each coupling has its own characteristics and the scope of the basic Can meet the needs of a variety of conditions, under normal circumstances, designers do not need to design their own coupling, only in the existing standard coupling can not meet the need to design their own coupling. Standard coupling easy to buy, the price than the design of non-standard coupling to be much cheaper. In many of the standard coupling, the correct choice for their needs the best coupling steel structural drilling machine, related to mechanical products shaft drive performance, reliability, service life, vibration, noise, energy saving, transmission efficiency, transmission accuracy, Economic and a series of issues, but also related to the quality of mechanical products. Designers in the selection of coupling should be based on the perspective of the shaft drive and the need to select the coupling, should be avoided only consider the main, driven side coupling selection coupling.

hydraulic hole punch machine
First, the choice of coupling factors should be considered
(A) the mechanical characteristics of the power machine
Power machine to the work machine, through one or several different varieties and specifications of the coupling will be the main and driven side together to form a shafting transmission system. In mechanical transmission, the power machine is nothing more than motors, internal combustion engines straightening machine and gas turbines. As the working principle of the power machine and different institutions, its mechanical characteristics vary widely, and some smooth operation, and some operation when the impact of the formation of the transmission system ranging from the impact. According to the mechanical characteristics of the engine, the power machine is divided into four categories. Universal coupling, see Table 1.

Type code of power machine Name of power machine Power factor (kw)
Motors, turbines 1.0
Four cylinder and four cylinder or more internal combustion engine 1.2
Two cylinder internal combustion engine 1.4
Single cylinder internal combustion engine 1.6

The mechanical characteristics of the power machine have certain influence on the whole transmission system. For different types of power machines, due to their different mechanical properties, the appropriate power factor Kw should be selected to select the optimum coupling suitable for the system. The type of power machine is to select the basic factors of coupling varieties, the power of the power machine is to determine the size of one of the main specifications of the coupling, and the coupling torque is proportional. Fixed mechanical products Powertrain in the drive system are mostly motors, mechanical products to run the drive system (such as ships, all kinds of vehicles, etc.) in the power engine for the internal combustion engine, when the engine for the cylinder number of different internal cnc drilling machine combustion engine, must consider torsional vibration Transmission system, the impact of this factor and the internal combustion engine cylinder number, the cylinder is working properly. At this point the general should be used in flexible coupling to adjust the shaft natural frequency, reduce the torsional vibration amplitude, thereby reducing vibration, buffer, protect the transmission components, improve the performance and improve the stability of the output power.
(B) load categories
Due to the different structures and materials, the coupling capacity of the couplings used in the drive systems of the various mechanical products varies greatly. Load category is mainly for the working load of the impact of the work load, vibration, reversing, braking, frequent start and other reasons to form different types of load. To facilitate the selection of the calculation, the transmission system load is divided into four categories, see Table 2.
Table 2 Load categories

Load Category Load condition Operating factor (k)
Load evenly, work smoothly 1~1.5
Medium impact load 1.5~2.5
Heavy shock load, frequent positive and negative rotation 2.5~2.75
Special heavy impact load, frequent positive and negative rotation >2.75

The load category of the transmission system is the basis for selecting the variety of couplings. Shock, vibration and torque changes in the larger working load should be selected with flexible components that flexible coupling flexible coupling to cushion, damping, compensation axis offset, improve the transmission performance. Start frequently, forward and reverse, the torque is normal braking when the torque is several times the work is overloading work, will inevitably shorten the life of coupling elastic components, coupling only allows short-term overload, the general short-term The overload shall not exceed 2 to 3 times the nominal torque, ie [Tmax] ≥ 2 to 3T n.
Low-speed conditions should avoid the use of only suitable for small and medium-power coupling, for example: elastic sleeve pin coupling, core type flexible coupling, polygonal rubber coupling, tire-type coupling, etc .; need to control overload Safety coupling should be selected with safety coupling, and elastic drill machine coupling with elastic element and better cushioning and damping effect should be selected for shaft system with large load variation and impact and vibration. Elastic couplings have higher load-carrying capacity than non-metallic elastic couplings. Elastic couplings with elastic elements are more reliable than elastic couplings for shearing elastic elements.
(C) the allowable coupling speed
The permissible speed range of the coupling is determined by calculation based on the permissible line speed and maximum outer edge dimensions for the different materials of the coupling. Different materials and varieties, specifications of the coupler allows the speed range is not the same, change the coupling material can improve the coupling allowable speed range, material for steel permissible speed is greater than the material for the cast iron permissible speed. For n> 5000r / min working conditions of the coupling, coupling should consider the outer edge of the centrifugal force and deformation of elastic elements and other factors, and should be dynamic balance. High-speed elastic coupling should not use non-metallic elastic components, the formation of high-speed elastic deformation, should use high-precision flexible coupling, the current foreign high-speed coupling for nothing more than diaphragm coupling and High – precision drum – shaped gear coupling. Universal coupling
(D) coupling the shaft displacement relative to the two axes
The coupling of the two shafts due to manufacturing errors, assembly errors, installation errors, shaft load and deformation, deformation of the base, bearing damage, temperature changes (thermal expansion, cold shrink), the relative movement between components Relative displacement. (X), radial (y), angular (α), and displacement of the shafting under different operating conditions, and the displacement of the two axes is not easy to avoid. In general, The size varies. Only the flexible coupling has to compensate for the relative displacement of Head punching machine the performance of two axes, so a large number of practical applications in the selection of flexible couplings. Rigid coupling does not have compensation performance, the scope of application is limited, so little use. Angle (α) the only larger shafting should use universal coupling, axial movement, and the need to control the axial displacement of the shaft drive, should use diaphragm coupling; only the precision is very High selection of rigid couplings, the standard flexible coupling allowable compensation in Table 3.

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