Diaphragm couplingThe assembly on the shaft is one of the keys to the installation of the coupling.The fit between the diaphragm coupling and the shaft is mostly interference fit. The connection is divided into keyed and non-keyed connections. The shaft hole of the elastic diaphragm coupling is divided into two forms: cylindrical shaft hole and tapered shaft hole .The assembly methods include static press-in method, dynamic press-in method and temperature difference assembly method.
(1) Static press-in method: This method uses clamps, jacks, manual or motorized presses according to the required press-in force during assembly. The static press-in method is generally used for tapered shaft holes. .Because the static press-in method is restricted by the pressure machine, it is difficult to apply a large force when the interference is large.At the same time, during the press-in process, the uneven small peaks on the mating surface between the elastic diaphragm coupling and the shaft will be cut off, causing the mating surface to be damaged.Therefore, this method is generally not widely used.
(2) Power press-in method: This method refers to the use of impact tools or machinery to complete the assembly process. It is generally used in situations where the coupling and shaft fit is transitional or has little interference.The method of hammering is usually used at the assembly site. The method is to put wooden blocks or other soft materials on the end surface of the wheel hub as a buffer, and rely on the impact force of the hand hammer to knock in the elastic diaphragm coupling.This method has the risk of local damage to the coupling made of brittle materials such as cast iron, quenched steel, cast alloy, etc., and should not be used.This method will also damage the mating surface, so it is often used for the assembly of low-speed and small couplings.
(3) Temperature difference assembly method: The coupling is heated to expand by heating or the shaft end is cold and contracted by cooling, so that the wheel coupling can be easily installed on the shaft.This method has more advantages than the static press-in method and the dynamic press-in method. For the wheel hub made of brittle materials, the temperature difference assembly method is very suitable.The temperature difference assembly method mostly adopts heating method, and the cooling method is less used.There are many heating methods. Some put the wheel hub in high flash point oil for oil bath heating or welding torch baking, and some use an oven to heat it. The assembly site uses oil bath heating and welding torch baking.The maximum temperature that the oil bath can reach depends on the nature of the oil, and it is generally below 200°C.When using other methods to heat the hub, the temperature of the elastic diaphragm coupling can be higher than 200℃, but from the perspective of metallography and heat treatment, the heating temperature of the coupling cannot be increased arbitrarily, and the recrystallization temperature of steel is 430℃ .If the heating temperature exceeds 430°C, it will cause changes in the internal structure of the steel. Therefore, the upper limit of the heating temperature must be less than 430°C.For insurance, the upper limit of heating temperature should be below 400℃.As for the actual heating temperature of the coupling, it can be calculated according to the interference value of the shaft and the shaft and the requirements when the elastic diaphragm coupling is heated on the shaft.