The disassembly of rolling bearing is one of the important disassembly contents in mechanical maintenance. The disassembly must follow the basic rules of bearing disassembly, and different disassembly tools and methods should be used for different bearings. When the bearing is tight fit with the shaft and loose fit with the seat hole, the bearing and shaft can be removed from the housing together, and then the bearing can be removed from the shaft with a press or other removal tools.
Here are some common bearing disassembly methods:
1. Removal of inner/outer ring.
Dismantle the outer ring of interference fit, set several screws for extruding the outer ring screw on the circumference of the shell in advance, tighten the screw evenly on one side, and disassemble at the same time. These screw holes are usually covered with blind plugs, tapered roller bearings and other separate bearings. Several notches are set on the housing shoulder, and cushion blocks are used to disassemble them with a press or by tapping gently.
2. Removal of cylindrical hole bearing
It is easiest to pull out with a press. At this time, pay attention to let the inner ring bear its pulling force. The inner ring of large bearing is disassembled by oil pressure method. The oil pressure is applied through the oil hole arranged on the shaft to make it easy to pull. For bearings with large width, oil pressure method and drawing fixture can be used together to remove them. The inner ring of NU and NJ cylindrical roller bearings can be disassembled by induction heating. It refers to the method of heating parts in a short time to expand the inner ring and then drawing.
3. Removal of tapered hole bearing
Remove the relatively small bearing with tight sleeve, support the inner ring with the stop fastened on the shaft, turn the nut back several times, and then use the cushion block to knock it with a hammer for removal. For large bearings, it is easier to disassemble the bearing by using oil pressure. It is a method of disassembling the bearing by pressurizing the oil hole on the tapered hole shaft to make the inner ring expand. During operation, there is a danger that the bearing will suddenly come out. It is better to use the nut as a stop.
4. Knockout method
Knocking is the simplest and most common method of disassembly. It is a disassembly method that uses the force of hammering to make the matched parts move and separate from each other to achieve the purpose of disassembly. The machine structure is relatively simple, and the parts are solid or some unimportant parts. Most of them are disassembled in this way. Before disassembly, in order to reduce friction, always soak the joints with lubricating oil. Knocking is a simple and easy method of disassembly. The commonly used tools for striking and disassembling are hand hammers, namely ordinary bench workers' hand hammers, punches and cushion blocks. The punch is made of steel, and the top of the hammered part is processed into a sphere, so that the end in contact with the workpiece is usually inlaid with soft metal, such as copper, aluminum, etc., and made into a flat or suitable shape for the workpiece, so as to protect the workpiece surface from damage. Different methods and steps shall be taken according to different machine structures during striking. The sleeve of sliding bearing and the outer sleeve of rolling bearing belong to interference fit in the hole, and they are usually taken out by striking. When removing, the end face of the bushing hammered shall be padded with cushion blocks. When removing the bushing with small diameter, it is better to use a step punch. The small diameter of the punch is just matched with the inner hole of the bushing. The large diameter of the punch is about 0.5mm smaller than the outer diameter of the bushing. For the disassembly of large diameter bushings and rolling bearings, bushings are often used. The removal of ordinary small bearing covers usually adopts the method of symmetrically driving inclined pads to open the bearing covers.
5. Press and pull
Press unloading and pull unloading have many advantages over blow unloading. They apply uniform force, and the force size and direction are easy to control. They can remove large parts and components with large interference, and this method of disassembly has less chance to damage parts. However, press and pull unloading require corresponding machinery and tools. Pressure machine tools are required for pressing and unloading. Common pressure machine tools include mechanical press, friction press and hydraulic press. The drawing die is often used for pulling and unloading. The drawing die can be divided into fixed arm and movable arm, as well as two claws and three claws. The tension applied by the drawing die claw should be applied to the inner ring of the bearing. If the structure is special and it is unable to pull the inner ring, the outer ring can be pulled.