Double Diaphragm Couplings

Double diaphragm coupling is a flexible coupling with multi-layer stainless steel diaphragm group as the core component, belonging to a type of metal elastic element coupling. It forms an elastic deformation structure by connecting two sets of staggered membranes and bolts, which can effectively compensate for the axial, radial, and angular relative displacement between the transmission shaft systems. This type of coupling has a wide range of applications in the industrial transmission field, especially suitable for situations that require high precision, high speed, and harsh working conditions.

The core component of the double diaphragm coupling is a diaphragm group composed of multiple layers of stainless steel thin plates stacked together, and each group of diaphragms is connected between the two halves of the coupling by high-strength bolts in a staggered manner. According to the different shapes of the membrane, it can be divided into two main types: linkage type and integral type.

Its working principle relies on the elastic deformation of the diaphragm to compensate for the relative displacement of the two connected axes. When there is misalignment between the two axes, the diaphragm absorbs these deviations through its own flexible deformation, thereby reducing the additional load on the bearings and shaft system. This design enables the double diaphragm coupling to simultaneously compensate for axial displacement (up to ± 0.5mm), radial displacement (up to ± 0.2mm), and angular displacement (up to 1.5 °).

The double diaphragm coupling has multiple excellent technical features:

1. Non lubrication design: The all metal structure does not require lubrication, avoiding lubricant leakage and contamination issues, making it particularly suitable for industries with high cleanliness requirements such as food and medicine.
   

2. High transmission efficiency: The transmission efficiency can reach 99.86%, with almost no energy loss, far higher than the gear coupling that requires lubrication.
   

3. Resistant to harsh environments: Made of stainless steel material, it has acid and alkali resistance, anti-corrosion properties, and a wide working temperature range (-80 ℃ to+300 ℃).
   

4. High speed capability: High balance accuracy, with a maximum speed of 6000r/min, suitable for high-speed transmission applications.
   

5. Zero backlash: Provides precise transmission ratio, no reverse backlash, suitable for precision transmission systems.
   

6. Long life maintenance free: No wear and tear parts, the service life can reach more than 10 years under normal use conditions, and there is basically no need for maintenance.
   

7. Vibration damping characteristics: The diaphragm group can effectively absorb and buffer vibrations, reducing system noise.

Double diaphragm couplings can be divided into various models and series according to their structure and application:

1. JMI type: standard double diaphragm coupling, suitable for general industrial transmission
   

2. JMIJ type: with an extended intermediate shaft, suitable for long wheelbase connections
   

3. JMII type: high torque type, with a static torsional stiffness of up to 3400N · m/rad
   

4. JMIIJ type: high torque with intermediate shaft type
   

5. SJM type: special high temperature and high pressure type, suitable for extreme working conditions

The static torsional stiffness range of these models is usually between 450-3400N · m/rad, and users can choose the appropriate model according to the stiffness requirements of the transmission system.

The application range of double diaphragm couplings is extremely wide, covering almost all industrial fields that require precision transmission:

1. Energy and electricity: generator sets, steam turbines, boiler feedwater pumps
   

2. Petrochemical industry: compressors, chemical pumps, petroleum machinery
   

3. Metallurgical mines: rolling mills, mining machinery, metallurgical equipment
   

4. Marine aviation: ship power system, helicopter transmission system
   

5. General machinery: fans, water pumps, printing machinery, textile machinery
   

6. Precision machinery: CNC machine tools, servo systems, force measuring devices

It is worth mentioning that in high-power fan systems, double diaphragm couplings can perfectly replace hydraulic couplings, achieving more efficient transmission. Installation only takes one day and has minimal impact on production.

The correct installation is the key to ensuring the long-term reliable operation of the double diaphragm coupling:

1. Bolt installation direction: It must be inserted from the outside of the flange hole to ensure the surface integrity of the bolt and flange fitting section.
   

2. Coordination gap control: The gap between the bolt and the flange small hole should be controlled at 0.20-0.30mm, and the gap between the buffer sleeve and the inner hole of the diaphragm rivet should be 0.5-0.7mm.
   

3. Alignment adjustment: after installation, the alignment of the two shafts shall be checked, and the radial deviation, angular deviation and axial deviation shall be within the allowable range.
   

4. Tightening sequence: The bolts should be tightened in stages in diagonal order, and the final torque should reach the specified value.
   

5. Regular inspection: During the initial operation, the bolt tightening status should be checked regularly, and during long-term operation, attention should be paid to observing for any abnormal vibration or noise.

Choosing a suitable double diaphragm coupling requires consideration of the following key parameters:

1. Torque characteristics: including rated torque, peak torque, and starting torque. The rated torque of the coupling should be greater than the maximum working torque of the system.
   

2. Speed range: The working speed should be within the allowable speed range of the coupling, taking into account the influence of centrifugal force.
   

3. Deviation compensation capability: Select a model with sufficient compensation capability based on the expected shaft deviation.
   

4. Environmental conditions: Consider the impact of environmental factors such as temperature, humidity, and corrosive media on materials.
   

5. Space limitation: The external dimensions and weight of the coupling should meet the installation space requirements.
   

6. Special requirements: such as explosion-proof, food grade, insulation and other special application requirements.

The double diaphragm coupling has become an indispensable key component in modern industrial transmission systems due to its excellent performance and reliability. It perfectly balances the relationship between transmission accuracy, compensation capability, and durability, demonstrating irreplaceable advantages in numerous application scenarios. With the continuous advancement of manufacturing technology, double diaphragm couplings will continue to expand their application boundaries, providing more efficient and reliable solutions for industrial transmission.

For users, correct selection, standardized installation, and appropriate maintenance are key to fully utilizing the performance of double diaphragm couplings. It is recommended to consult professional technicians when selecting, and choose the most suitable product model and configuration based on specific working conditions.