After testing and verification of a certain type of permanent magnet motor , it was planned to disassemble the rotor to inspect the magnets. However, it was discovered that the bearing disassembly tools could not be inserted because the inner cavity of the housing was too tight. The assembly worker grabbed an iron hammer and was about to use his "superpower" to knock it off, but Ms. saw this and immediately stopped him.
Bearing disassembly
Disassembling bearings is a very delicate task, and a crude or simplistic approach by the assembly worker can undoubtedly leave fatal hidden dangers. Ms. Can guided the creation of a simple disassembly tool kit, complete with screws and nuts, making the process easy. Furthermore, bearings are extremely precise parts, and strong impacts, rust, and other adverse conditions should be avoided.
Preparation before installation
● Before installing bearings, you need to prepare a clean and dry work area, tools, measuring instruments, lubricant, and clean cloths. Especially when installing miniature, small ball bearings, and precision bearings, the presence of garbage or foreign objects can have a significant impact on bearing performance. Therefore, it is best to carry out the installation work in a clean room.
In addition, before installing the bearing, dirt, burrs, and metal shavings should be removed from the shaft, bearing housing, and other related parts and installation tools. At the same time, the dimensional accuracy, shape accuracy, and roughness of the bearing mounting surfaces should be checked and confirmed to ensure they are within allowable tolerances.
● Bearings must be unpacked just before installation. Normally, when using grease lubrication, the rust inhibitor can be installed and used directly without washing it off. However, when using oil lubrication, and even in some cases of grease lubrication, the rust inhibitor on the bearing must be washed off with clean cleaning oil. The bearing should only be installed after the cleaning oil has completely dried or been wiped completely dry to prevent the lubricant and rust inhibitor from mixing and affecting lubrication.
Note: Do not clean bearings with double dust covers and seals.
Install
Press in
Press-fit is one of the simplest installation methods and is suitable for installing small to medium-sized bearings. For bearings with small interference fits, even pressure can be applied to the raceway circumference at room temperature to press them in. When installing a non-separable bearing on both a shaft and a bearing housing, use shims on the bearing and apply even pressure to both the inner and outer rings to press them in.
Precautions
●If the pressure applied during insertion is too high, burns and cracks may occur due to insufficient internal clearance of the bearing.
● Excessive impact load during installation may cause indentations and damage.
● During installation, please take care to prevent foreign objects from entering the mating surfaces.
Hot Pack
Under no circumstances should the bearing temperature be heated above 120°C. Immersing the bearing in heated clean oil is also an option, but oil temperature control is crucial; the heating temperature must not exceed 120°C. However, this method is not suitable for bearings with dust covers or seals that have already been filled with grease.
The general method for heating bearings is as follows:
1) When heating bearings by immersing them in heated clean oil, to prevent uneven heating, the bearings can be placed on a wire mesh or suspended in the oil for heating.
Do not use a burner to heat the bearing. This heating method may cause localized overheating of the bearing, which can easily lead to bearing damage and shorten its lifespan.
2) Heating the bearings in the atmosphere using a constant temperature bath or similar equipment.
You can use the bearing directly in a dry state, but it takes time for the bearing to heat up. Therefore, please use a contact thermometer or similar device to measure the bearing temperature to ensure that the bearing has indeed reached the target temperature.
3) Method of heating bearings using induction heating devices
Compared with oil bath heating and constant temperature bath heating, it has the advantages of safety, cleanliness, and speed. The induction heating device consists of an iron frame with multiple coils wound around it.
When current flows through the primary coil (low-voltage coil), the coil generates a magnetic field, which in turn induces current at the bearing, which is equivalent to the secondary coil (high-voltage coil) of a transformer. When a strong low-voltage alternating current flows through the bearing, the non-metallic parts and components remain at a low temperature, while only the bearing heats up for a short time.
The bearing is magnetized by induction heating and must be demagnetized after cyclic heating.
4) Hydraulic installation
When installing large tapered bore bearings, simply tightening the locking nut (screw) is insufficient. A hydraulic installation method is required, specifically: ① Apply hydraulic pressure to the clearance between the bearing and the shaft to form an oil film. This reduces friction during installation and facilitates tightening. ② Inject high-pressure oil into the hydraulic nut to generate the axial force (thrust) required for installation. This further simplifies bearing installation.
The above two operations can be performed simultaneously. The residual clearance after bearing installation can be confirmed using a feeler gauge or by measuring the axial backward movement of the inner ring during installation.
Precautions for hot packing
●The key to hot-loading is that it needs to be completed in a short time.
●After inserting the heated bearing into the shaft, continue to press the inner ring and shaft shoulder until the bearing cools down. After it has cooled to room temperature, tighten the bearing using a stamping or similar method.
●If the bearing cannot be installed during the hot-fitting process, please stop the operation and remove the bearing.
● During installation, apply an anti-abrasion agent to the mating surfaces of the shaft or bearing housing and the bearing to prevent rusting.
If you need to use heated bearings, you should wear heat-resistant gloves for safety.
