What is the function of elastic pin coupling to cushion and absorb vibration?

The elastic pin coupling is a kind of coupling, which plays a very important role in the rotation of the motor. So, what is its buffering and vibration absorption function? The following is a small series about couplings I hope everyone can gain something!

The function of elastic pin coupling to buffer and absorb vibration

Due to the elastic element of the elastic pin coupling, the elastic element can produce greater elastic deformation and damping. Therefore, the elastic coupling can not only compensate for the relative displacement of the two shafts, but also cause buffering and vibration absorption.

In the process of mechanical transmission, the load transmitted by the transmission shaft system often changes. The reasons for the load change are different, such as unstable motor speed, unstable load of working machine and centrifugal force caused by unbalanced rotating parts in the shaft system. Dynamic loads may cause changes in load.Load changes are often reflected in periodic loads, impact loads and irregularly changing loads. Elastic couplings can adapt to load fluctuations and have the ability to buffer and dampen vibrations, which are mainly related to the stiffness and damping of the elastic coupling.

The stiffness of the coupling includes radial stiffness, axial stiffness and torsional stiffness.In actual engineering, the load changes are often caused by torsional vibration due to torque fluctuations, so the main stiffness of the coupling is the torsional stiffness.In general, in shafting transmission, the stiffness of other parts of the system will be much larger than that of the elastic coupling. Therefore, in the simplified case, assuming that the elasticity of other parts is zero, only the coupling is considered.的flexibility.The torsional stiffness of the coupling is used as the torsional stiffness of the drive shaft system.

Although elastic couplings generally have buffering and vibration absorption functions, elastic couplings with a certain value of stiffness cannot produce vibration reduction effects under the action of any variable torque, but sometimes cause more intense vibrations. .Therefore, only when the stiffness of the coupling is coordinated with other parameters and loads of the entire drive shaft system can the effect of vibration reduction be produced.For a certain drive shaft system, the moment of inertia and natural frequency can be obtained. If you know the changing law of the transmitted torque, such as amplitude and frequency, you can establish the differential equation of the shaft system in torsional vibration and solve the equation , You can get the required coupling stiffness.In order to facilitate the solution of the differential equations of motion, it is necessary to simplify the mechanical models of the moment of inertia and stiffness on the driving and driven sides of the coupling in the transmission shaft system.Usually it is more typical to simplify into two equivalent discs, which are arranged on both sides of the coupling.During the work of the coupling, the cyclic load is a typical load form in mechanical transmission.In order to avoid resonance, the changing frequency of the periodic load and the natural frequency of the drive shaft should be staggered.The method is to change the change frequency of the periodic load or change the change frequency of the shaft system.Because the change frequency of the load is related to the speed of the spindle, and the speed is a mechanical performance parameter, generally it cannot be changed at will.Therefore, the purpose of not resonating is generally achieved by changing the natural frequency of the shafting system, and changing the natural frequency of the shafting system generally changes the moment of inertia or stiffness of the shafting system. The moment of inertia is related to the mechanical structure, and it is difficult to achieve by changing the moment of inertia. , And the stiffness of the shaft system is easy to change.Therefore, changing the star-shaped elastic coupling is to change the stiffness of the shaft system to achieve the purpose of avoiding resonance.

Precautions for selection of elastic pin coupling

The principle of coupling needs should be considered based on six aspects: speed, torque, assembly and disassembly, neutrality, cost, and environment.

The principle of coupling needs should be considered based on the six aspects of speed, torque, assembly and disassembly, neutrality, cost, and environment: Principles for selection of elastic pin couplings:

1. Choose the appropriate form: Determine the appropriate type according to the requirements of mechanical characteristics, such as transmission torque, stiffness requirements, vibration, impact, acid and alkali corrosion resistance, transmission accuracy, etc.

2. Calculate the torque

The large torque transmitted by the coupling should be less than the allowable torque value.The determination of large torque should consider the acceleration and deceleration torque and overload torque required for machine braking.However, when the design data is insufficient or the analysis is difficult, and the large torque is difficult to determine, the calculated torque can be selected.That is, the calculated torque does not exceed the allowable torque value.

Calculate torque Tc: use the following formula to calculate Tc=KT T=9550*(Pw/n) T=7020*(Ph/n) where T——theoretical torque, N*m

k——driving power, kw Ph——driving power, horsepower n——rotating speed, rpm

3. Select the type of shaft hole and key (or expansion coupling sleeve).

4. Determine the aperture range (Note: When the diameter of the driving and driven shafts are different, the coupling specifications should be selected according to the large end diameter)

5. Rotation speed n: n ↑, flexible coupling of non-metal elastic elements;

6. Torque T: T ↑, choose rigid coupling, non-elastic element or flexible coupling with metal elastic element; T has impact vibration, choose flexible coupling with elastic element;

7. Assembly and disassembly: Considering the convenience of assembly and disassembly, choose a coupling that can directly move radially;

8. Alignment: For good alignment, choose a rigid coupling, and when compensation is needed, choose a flexible coupling;

9. Cost: Under the same conditions, try to choose a coupling with a low price and simple maintenance;

10. Environment: If working at high temperatures, couplings with non-metallic components cannot be selected.

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