What kind of operation needs to choose plum coupling?

The plum coupling is the key equipment in the transmission system. Generally, the use time is relatively long. So how to choose the plum coupling? The following is the content about the plum coupling brought by the editor, hoping to make us have a harvest !.

Plum blossom coupling process

　　 The plum blossom coupling has a good balance function and is suitable for high-speed applications (the speed can reach 30000 rpm), but it cannot handle large errors, especially axial errors.Larger misalignments and deflection angles will produce larger bearing loads than other servo couplings.Another important issue is the failure of the plum coupling.Once the quincunx elastic distance body is damaged or fails, the torque transmission will not stop, and the metal claws of the two shaft sleeves mesh together to continuously transmit the torque, which may cause problems in the system.It is a big advantage of this coupling to select suitable plum elastic distance body materials based on practical application. Different hardness and temperature tolerance allow customers to select suitable materials to satisfy the practical application of the functional specifications.Due to the special production process of plum coupling castings, the appearance of the castings is simply rusted, and it is difficult to handle after rust. If you do not pay attention to it, not only the work piece has poor anti-corrosion ability, but also poor decoration. Many companies are responding to this problem. The castings put forward higher requirements for corrosion resistance. According to the different operating conditions of the castings, the castings (cast iron, cast steel) are required to be blackened at room temperature, phosphating treatment and other special anti-rust treatments.The difference between plum blossom coupling cast iron parts and other steel parts is that the arrangement is loose and the carbon content is high. If it is not handled properly, it will directly affect the bonding strength of the blackened film and the substrate. Therefore, the pretreatment is particularly important.Briefly introduce several anti-rust methods of plum coupling castings and the situation of related products.General pre-treatment includes degreasing and rust removal. When degreasing, it is necessary to remove the surface oil and clean, and can not use strong alkali to prevent the matrix from over-corrosion.There are many degreasing methods, such as mechanical degreasing, organic solvent degreasing, chemical degreasing at various temperatures, and electrolytic degreasing, etc., which can be selected according to their own existing conditions.The rust removal activation can be determined according to the condition of the substrate. If the rust and scale are heavy, first choose sandblasting and then turn black. If the appearance is better, you can choose hydrochloric acid activation, but you must be careful not to overcorrosion.Otherwise, the appearance of the carbon film assembly is difficult to clean, and the appearance will be grayed out after blackening, which will also affect the binding force.Regarding the cooperation between the plum blossom coupling and the shaft with corresponding gaps, the direct installation of lubricating grease can be modified after the clean cooperation appearance is cleaned up.Regarding the transitional cooperation and the cooperation that is not very large, there may be special requirements for cooperation (such as maintaining the installed fine parts). Press-in method can be used, but the equipment needs to be pressed-in.The operation of the thermal device of the coupling is often used in the installation of heavy equipment such as large motors, compressors and rolling mills, because the coupling and shaft in this type of equipment are generally connected by interference cooperation.There are several methods for the installation of interference couplings: press-in device, low-temperature cooling device and hot-jacket device.The cold shrinkage device method generally uses liquid nitrogen as a cold source, and requires a certain insulation container, so it can only be selected when conditions permit.The essential principle of the heating jacket device is to heat the receiving part (hole) to increase its diameter by a cooperative interference value, and then install it into the contained part (shaft). After cooling, the machine will reach the required bonding strength.In practice, the heating expansion value must be larger than the cooperation interference value to ensure a smooth installation and avoid serious accidents of shaft and hole jamming due to the cooling of the receiving parts during the installation process.At the same time, in order to ensure a greater meshing force-bonding strength, the bonding surface of the heating sleeve device must be processed, but not too bright. Due to a certain surface roughness (usually Ra3.2), it is not affected by axial movement. After being flattened and cooled, the bonding strength of the front and back parts will be greater, and the torque that can be transmitted will also be greater.There are two main types of plum couplings, one is the traditional straight claw type, and the other is the curved (concave) claw type with zero gap.The traditional straight-jaw plum blossom coupling is not suitable for high-precision servo transmission applications.The zero clearance claw type plum blossom coupling is evolved on the basis of the straight claw type, but the difference is that its design can be suitable for the application of the servo system, and it is often used to connect servo motors, stepping motors and ball screws.The curved surface is to reduce the deformation of the elastic plum distance body and restrain the influence of centripetal force on it during high-speed operation.The zero gap claw coupling is composed of two metal bushings (usually made of aluminum alloy material, stainless steel material can also be supplied) and a plum blossom elastic distance body.The quincunx elastic distance body has multiple leaf branches, like the slider coupling, it also squeezes the quincunx elastic distance body and the shaft sleeves at both ends, and thus ensures its zero gap function.Different from the slider coupling, the plum blossom coupling is driven by squeezing while the slider coupling is driven by shear.When using the zero clearance claw coupling, the user must be careful not to exceed the capacity of the elastic element given by the manufacturer (under the premise of ensuring zero clearance), otherwise the quincunx elastic distance body will be squashed and deformed and lose its elasticity , The preload disappears, resulting in the loss of the function of zero gap, and the user may only find out after a serious problem occurs. 1. It has high elasticity (low rigidity, high flexibility), the rotation angle is 10 degrees when bearing the nominal torque, and 25 degrees when the torque is applied. It can reduce the natural vibration frequency of the shaft system and change the torsional vibration characteristics of the diesel engine power unit shaft system. So that the diesel engine does not appear dangerous resonance speed within the required speed range. 2. It has good damping and vibration reduction characteristics, which can absorb some vibration energy, reduce the vibration amplitude when passing through the vibration point, and reduce the torsional vibration stress of the shaft section. 3. It has high elasticity (low rigidity, high flexibility), the rotation angle is 10 degrees when bearing the nominal torque, and 25 degrees when the torque is applied. It can reduce the natural vibration frequency of the shaft system and change the torsional vibration characteristics of the diesel engine power unit shaft system. So that the diesel engine does not appear dangerous resonance speed within the required speed range.It can absorb and reduce the inconsistency of the output torque of the diesel engine. For the diesel engine power unit equipped with a reduction gear box, it can reduce the impact on the gear surface when the torque is changed, and extend the service life of the gear.  

Coupling selection procedure

When choosing a coupling, planners should first choose from the existing specifications, machinery industry specifications, and patented couplings. Only when the existing standard couplings and patented couplings cannot meet the planning requirements. Plan the coupling by yourself.

1. Use standard couplings.When choosing a coupling, planners should first choose from the existing specifications, machinery industry specifications, and patented couplings. Only when the existing standard couplings and patented couplings cannot meet the planning requirements. Plan the coupling by yourself.
2. Select the type and type of coupling
Understand the generalized functions of couplings (especially flexible couplings) in the transmission system, and select the type and type of coupling from the overall planning of the transmission system.Select the type of coupling based on the prime mover category and operating load category, operating speed, transmission accuracy, two-axis offset, temperature, humidity, operating environment and other summary factors.Select the structure of the coupling according to the needs of the supporting host. When the coupling is used in conjunction with the brake, a coupling with a brake wheel or a brake disc should be selected; when overload maintenance is required, the coupling should be selected; When connecting with flanges, the flange type should be selected; for long-distance transmission, when the axial dimension of the connection is large, the center shaft type or the center sleeve type should be selected.
3. Calculation of coupling torque
The power of the power machine in the transmission system should be greater than the power required by the work machine.According to the power and speed of the power machine, the theoretical short moment T of the high-speed end connected with the power machine can be calculated; according to the working condition coefficient K and other related coefficients, the calculation torque Tc of the coupling can be calculated.The coupling T is inversely proportional to n, so the low-speed end T is greater than the high-speed end T.
4. Primary selection of coupling type
According to the calculated torque Tc, a similar nominal torque Tn can be selected from the standard series, and the selection should be satisfied with Tn≥Tc.Start to select the coupling type (specification). From the specifications, you can find the allowable speed of the coupling [n] and the large radial dimension D and the axial dimension L0, and you are satisfied with the coupling speed n≤[n] .
5. Adjust the type according to the shaft diameter
The coupling dimensions selected at the beginning, namely the shaft hole diameter d and the shaft hole length L, should meet the requirements of the main and driven end shaft diameters. Otherwise, the coupling specifications must be adjusted according to the shaft diameter d.It is a general phenomenon that the shaft diameters of the driving and driven ends are different. When the torque and speed are the same, and the shaft diameters of the driving and driven ends are not the same, the coupling type should be selected according to the larger shaft diameter.In the newly planned transmission system, seven types of shaft holes that meet the rules in GB/T3852 should be selected, and the J1 shaft hole type is recommended to improve versatility and interchangeability. The length of the shaft hole is in accordance with the rules of the coupling product specification. .
6. Choose the connection type
The choice of coupling connection type depends on the connection type of the main and driven ends to the shaft. Generally, the key connection is selected, which is the unified key connection type and code. In GB/T3852, there are seven keyway types and four keyless connections. , The most used is the A-type key.

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