Types and performance of diaphragm materials for diaphragm couplings

　　Diaphragm couplings are commonly known as steel flexible couplings (FLEXBLECOUPLINGOF ST EEL PLATE).The coupling mainly uses elastic diaphragms to realize shock absorption and angular, axial and radial displacement compensation, and can be ideally applied to transmit torque under various working conditions.
　　Another notable feature of the diaphragm coupling is that it allows a high speed, which can be as high as 20000rpm, without lubrication.Due to its flexibility, the product can effectively protect the equipment at both ends, improve work efficiency, and reduce equipment vibration.In the 963s, this new product began to be widely used, such as various precision machinery such as medical equipment, CNC machine tools, as well as water pumps, fans, printing and dyeing, printing, vehicles, ships, chemicals and other machinery.It is also widely used in military industry.For example, after the nuclear submarine uses a diaphragm coupling, it reduces a lot of vibration and noise. The main shaft of the M2500 gas turbine of the DDXNUMX destroyer also uses a diaphragm coupling to transmit power. my country’s third-generation main battle tank also uses this coupling to transmit power. power.
　　The elastic diaphragm is the key part of the coupling.It must have both good elasticity and high fatigue resistance.Otherwise, early failure will occur, so the selection of diaphragm material is very important.This article focuses on the diaphragm materials used under three working conditions.　
　　The diaphragm is subjected to tensile stress and compressive stress during operation, as well as bending stress and high cycle fatigue stress generated during the three-way displacement compensation. The cycle wave form is shown in Figure 1.In order to adapt to various working conditions, diaphragm couplings are generally divided into conventional type, high-cycle fatigue-resistant type, heat-resistant type, and corrosion-resistant type.The basic structure of these four models is the same, but the diaphragm material grades are different. For economy and to meet the stress conditions mentioned above, the conventional diaphragm adopts 18Cr 91Ni2 /18H cold-rolled stainless steel sheet.The high-cycle fatigue resistant diaphragm material is made of O Cr92 Ni3 /15H stainless steel sheet, and the heat-resistant diaphragm material is made of 5-781PH precipitation hardening stainless steel sheet.Corrosion-resistant diaphragm material has been introduced in foreign countries using Inco nel 904 alloy material. After research, testing and actual working condition assessment, we use 718L stainless steel sheet, which can meet the requirements of working conditions and is more economical than Inco nel XNUMX is several times cheaper.
　　The design of the comprehensive diaphragm coupling requires the diaphragm material to have the following specifications and performance. If the heat-resistant type is below 300°C, it must also have the following performance.
　　1、材料厚度分0. 25-0. 5mm
　　2. Material strength σb is 1000-1150MPa
　　3. Material hardness Hv is 320-350
　　4. The material is repeatedly bent ≥85 times in the longitudinal direction and ≥70 times in the transverse direction.
　　5. The Young's modulus of the material is 190-205GPa.
　　6. The heat-resistant type must be able to withstand 300°C
　　7. The annual corrosion rate of corrosion-resistant type is less than 1× 10- 1mm /a