Industry news|2022-02-14| admin
R+W bellows coupling is mainly composed of two shaft sleeves and the middle bellows. Generally, welding and adhesion are used. The common type of shaft sleeve is made of stainless steel. is steel. The application industry of bellows coupling is also very extensive. Today, I will introduce the installation and disassembly of R+W bellows coupling. I hope it can help you!
Coupling installation and disassembly method
The device of the coupling belongs to a relatively simple maintenance process in the mechanical maintenance. In the coupling installation, the key points are to grasp the installation of the shaft sleeve on the shaft, the alignment of the two shafts connected by the coupling, the inspection of the parts and the installation of the coupling according to the drawing requirements.
1. The installation method of the shaft sleeve on the shaft
The installation of the shaft sleeve on the shaft is one of the key points of the coupling installation. The surface of the sleeve and the shaft is mostly interference cooperation, and the connection is divided into a keyed connection and a keyless connection; the shaft hole of the shaft sleeve is divided into two ways: a cylindrical shaft hole and a tapered shaft hole. The installation methods include static pressing method, dynamic pressing method, temperature difference installation method and hydraulic installation method.
(1) Static pressing method
This method is based on the size of the pressing force required for the installation on the shaft sleeve, using clamps, jacks, manual or motorized presses, and the static pressing method is generally used for tapered shaft holes. Because the static pressing method is constrained by the pressure machine, it is difficult to apply a large force when the interference is large. At the same time, in the process of pressing, the uneven small convex peaks on the cooperating surface between the sleeve and the shaft will be cut off, which will damage the cooperating surface. Therefore, this method is generally not used much.
(2) Power pressing method
This method refers to the use of impact tools or machinery to complete the installation process of the sleeve to the shaft, which is generally used for occasions where the coupling between the sleeve and the shaft is transitional or the interference is not large. The method of beating is usually used at the installation site. The method is to place wood blocks, lead blocks or other soft materials on the end face of the shaft sleeve as buffer parts, and rely on the impact force of the hand hammer to knock the shaft sleeve in. This method has the risk of local damage to bushings made of brittle materials such as cast iron, quenched steel, and cast alloys, and should not be used. This method will also damage the cooperative appearance, so it is often used for low-speed and small coupling devices.
(3) Temperature difference device method
The shaft sleeve is heated to expand by heating or the shaft end is shortened by cooling, so that the inner diameter of the shaft hole of the shaft sleeve is slightly larger than the diameter of the shaft end, that is, the so-called "simple device value" is reached, and no large amount of pressure is required. the force, the bushing can be easily sleeved on the shaft. This method has more advantages than the static pressing method and the dynamic pressing method. For the bushing made of brittle materials, the temperature difference device method is very suitable.
The temperature difference device method mostly uses the heating method, and the cooling method is used less. There are various heating methods. Some put the shaft sleeve into the oil with high flash point for oil bath heating or welding torch baking, and some use the oven to heat. Oil bath heating and welding torch baking are mostly used on the installation site. The maximum temperature that the oil bath can reach depends on the properties of the oil, and is generally below 200°C. When other methods are used to heat the bushing, the temperature of the bushing can be higher than 200°C, but from the perspective of metallography and heat treatment, the heating temperature of the rotation cannot be increased arbitrarily, and the recrystallization temperature of the steel is 430°C. If the heating temperature exceeds 430 °C, it will cause changes in the internal structure of the steel. Therefore, the upper limit of the temperature of the heat of the river must be less than 430°C. For insurance, the upper limit of heating temperature should be below 400℃. As for the heating temperature required for the practice of the bushing, it can be calculated according to the interference value of the cooperation between the bushing and the shaft and the requirements when the bushing is heated and assembled on the shaft.
(4) Inspection after installation
After the shaft sleeve of the coupling is installed on the shaft, the verticality and coaxiality of the shaft sleeve and the shaft should be carefully checked. Generally, two dial indicators are set on the end face and outer circle of the shaft sleeve. When the crankshaft rolls, the value of the full runout (including the end face runout and radial runout) of the shaft sleeve is investigated, and the perpendicularity between the shaft sleeve and the shaft is determined. and coaxiality. Couplings with different speeds have different requirements for full runout, and different types of couplings have different requirements for full runout. However, after the wheel is installed on the shaft, it is necessary to make the bushing full runout. The error value is within the tolerance range required by the design, which is one of the main quality requirements of the coupling device.
There are many reasons that the full runout value of the shaft sleeve does not meet the requirements. First of all, it may occur due to errors caused by processing during manufacturing. For field devices, it is mainly used to correct the appearance of the inner hole of the shaft sleeve. Concentricity error occurs. Another reason is that when the keyed coupling is installed, the coaxiality of the device is wrong due to the improper installation of the key. The correct installation of the key should make the two sides of the key closely fit with the wall of the keyway. Generally, it is checked by the coloring method during installation. When the cooperation is not good, it can be repaired with a file or a shovel to meet the requirements. There is generally a gap on the upper part of the key, about 0.1-0.2mm. High-speed rotating machinery has high requirements on the coaxiality of the device, and high coaxiality cannot be obtained by single-key connection. The coaxiality of the two can be improved by using double-key connection or spline connection.
2. Coupling device
Before the coupling is installed, clean the parts first. After cleaning, the cleaning oil on the parts should be wiped dry. Couplings that are ready to run in a short period of time can be coated with some oil on the surface of the parts after drying to avoid rusting. For couplings that need to be used for a long time, they should be coated with anti-rust oil for maintenance.
There are many structural types of couplings, and the detailed installation requirements and methods are different. As for the installation, the general principle is to install according to the requirements of the drawings. In detail, only some problems that often need attention in coupling installations can be introduced. . For couplings used in high-speed rotating machinery, a dynamic balance test is generally done in the manufacturer. After the dynamic balance test is passed, the symbol of the mutual cooperation between the components is drawn. It is very important to assemble according to the symbols given by the manufacturer when installing. If it is not assembled arbitrarily according to the symbols, it is likely to cause the vibration of the unit due to the poor dynamic balance of the coupling.
In addition, the connecting bolts on the flange of this type of coupling are load-bearing, so that the connecting bolts on each coupling can be basically the same in weight. For example, for the gear coupling used in large centrifugal compressors, the weight difference between the connecting bolts used and the phases is generally less than 0.05g. Therefore, the bolts between the couplings cannot be interchanged at will. If you want to replace One of the coupling bolts must have the same weight as the original connecting bolt. In addition: when tightening the coupling bolts of the coupling, it should be symmetric and gradually tightened, so that the locking force on the coupling bolts is basically the same, so that the coupling will not tilt after installation due to the uneven force of each bolt. , a torque wrench can be used if possible.
Regarding the rigid movable coupling, after the installation, it should be checked whether the rigid movable parts of the coupling can move a few times, and whether there is any jamming phenomenon.
After the various couplings are installed, check whether the rolling condition is in good condition. In short, the correct installation of the coupling can improve the operation of the equipment, reduce the vibration of the equipment, and extend the service life of the coupling. Dismantling is the opposite of the installation process, the purpose is different. The installation process is to assemble the coupling according to the requirements of the installation, so that the coupling can transmit torque safely and reliably. Disassembly is generally due to equipment failure or the coupling itself needs maintenance, and the coupling is disassembled into parts. The degree of disassembly generally depends on the maintenance requirements. Some only require the two shafts to be disconnected, and some not only need to disassemble all the couplings, but also remove the shaft sleeve from the shaft. There are many types of couplings with different structures, and the disassembly process of the coupling is also different. Here are some issues that need to be paid attention to in the disassembly of the coupling.
Because the failure of the coupling itself needs to be disassembled, first make a detailed inspection of the coupling as a whole (especially for the coupling that has been damaged), and the cause of the failure should be found out.
Before the coupling is disassembled, some marks should be made on the position of cooperation between the various parts of the coupling for reference when reassembling. Couplings used for high-speed machines, the connecting bolts are weighed, and the symbols must be clear and cannot be mistaken.
The above is the relevant knowledge about the installation method and disassembly of the R+W bellows coupling. For more product industry-related knowledge, you can consult Shenzhen sz-windrive Automation to provide model selection and product technical support!
