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 After running the bearing for some time, there will inevitably be needs for maintenance or damage replacement. In the early stage of the machinery industry development, the popularity of professional knowledge was not enough, and the awareness of safe operating procedures was not enough. Today we will only talk about the disassembly of bearings.


    Take a look at how the so-called Niu Ren dismantled the bearings in just one second.

    The above is a common practice of some people in real work. The efficiency is high. Maybe you are not damaged sometimes, but have you considered that the bearing surface is not damaged, but is there any damage inside?


     Besides, the bearing steel is relatively hard and brittle, and it is easier to fall under gravity. The consequences are unbearable. I am afraid that everyone feels bad. Some cases of bruises are not put on it. There must be scientific operating procedures and tools for bearing installation and disassembly. Only in this way can bearing play more perfectly.


    How to disassemble the bearing accurately and quickly also has many skills and knowledge, this article summarizes in detail.


     Safety first


     Any operation must be based on safety, and bearing disassembly is no exception. At the end of use, the bearing is likely to wear a certain amount. If the disassembly method is improper and the external force is applied unreasonably, it may cause the bearing to break and lead to the danger of metal fragments splashing. It is strongly recommended to add a protective blanket to cover the operation of bearing disassembly to ensure safe operation.


     Classification of bearing disassembly


     Under the condition that the support size is designed correctly, as long as the bearings with clearance fit are not deformed or destroyed due to excessive use and are stuck on the parts matched with them, the direction can be removed. The reasonable disassembly of bearings under interference fit is the core of bearing disassembly technology. Bearing the interference fit is divided into inner ring interference and external ring interference, which will be introduced separately for these two situations.


     1. The inner ring of the bearing is interference, the outer ring clearance fits


     1. Cylindrical shaft


     The correct bearing disassembly is inseparable from the use of tools. For small size bearings, the conventional device is a puller. The puller is divided into two kinds of two-jaw and three-jaw, divided into thread and hydraulic pressure.


     The thread puller is a relatively traditional tool. Its operation is to align the center screw with the center hole of the shaft, apply a small amount of grease to the center hole of the shaft, hook the claw to the end surface of the inner ring of the bearing, and twist the center rod with a wrench. The bearing can be pulled out. The hydraulic puller uses a hydraulic device to replace the thread. When the pressure is applied, the piston in the middle continuously extends, and the bearing will be continually pulled out. It is faster than the traditional thread puller, and the hydraulic device can quickly retract.


     In some designs, the distance between the end face of the inner ring of the bearing and other components is small, and there is no operating space for the claw of the traditional puller. In this case, a two-piece splint (see the following figure) can be used to select the appropriate size of the reinforcement, disassemble, and disassemble pressure. The brace can be made thinner locally, to penetrate narrow spaces.

  When a large batch of small-size bearings needs to be disassembled, a quick-disassembly hydraulic device can also be used.

  For the disassembly of integral bearings of railway vehicle axles, there is a unique mobile disassembly device.

When the size of the bearing is increased, the force required to disassemble the bearing also increases, and the universal puller cannot be applied. Special tooling needs to be designed for disassembly.

    When the disassembly force is too large to be removed by ordinary methods, and the disassembly force generated by the conventional approach is likely to damage the bearing, an oil hole is generally designed at the end of the shaft. Besides, an annular groove is added, and a hydraulic pump is used to pressurize the shaft end to expand the inner ring during disassembly, reducing the disassembly force.

    When the bearing is too significant, and the simple hard-pull type cannot be disassembled, the heating disassembly method is required. Before the operation, you need to prepare complete tools, such as jacks, height gauges, spreaders, and so on. The operation method of heating disassembly is to directly wind the coil on the raceway of the inner ring to heat it to expand so that the bearing is easily disassembled. Cylindrical bearings with separable rollers also apply the same heating method. This method allows the bearing to be removed without damage.

 The setting of the heater heating temperature must not exceed 120 degrees Celsius, because the disassembly of the bearing requires a rapid temperature difference and operation process, not heat. If the ambient temperature is high or the interference is substantial, and the temperature difference is insufficient, dry ice (stable carbon dioxide) can be used as an auxiliary means to place the dry ice on the inner wall of the hollow shaft to quickly reduce the temperature of the cylinder (such large-sized workpieces are generally), Thereby increasing the temperature difference.


     For the disassembly of the tapered bore bearing, do not entirely remove the clamping nut or mechanism at the end of the shaft before disassembly, loosen it to avoid the bearing falling accident.


Disassembly of large-sized tapered shafts requires the removal of oil holes. Take the four-row tapered bearing TQIT of the conical inner hole of the rolling mill as an example. The inner ring of the bearing is divided into three parts, two single-row inner rings and a double inner ring in the middle. There are three oil holes at the end of the roll, corresponding to the mark 1, 2,3, where one corresponds to the outermost inner ring, two corresponds to the double inner circle at the middle position, and three corresponds to the innermost ring with the largest diameter. When disassembling, disassemble in the order of serial numbers and pressurize holes 1, 2, and 3. When the driver can lift the bearing after all are completed, the hinge ring at the end of the shaft is removed, and the bearing is removed.


     If the bearing needs to be used again after disassembly, the force applied during disassembly must not be transmitted through the rolling elements. For split bearings, the bearing ring with the rolling element cage assembly can be removed separately from the other bearing ring. When disassembling non-separable bearings, you should first remove the bearing rings with clearance fits. To disassemble the interference fit bearings, you need to use different tools according to their type, size, and matching method.


When disassembling smaller bearings, you can use a suitable punch to gently tap the side of the bearing ring to remove it from the shaft. A better method is to use a mechanical puller (Figure 1). The grip should act on the inner circle or adjacent parts. If the shaft shoulder and the bearing seat hole shoulder are provided with grooves to accommodate the puller, the disassembly process can be simplified. Besides, some threaded holes are machined at the position of the hole shoulder to facilitate the bolt to push the bearing out.

Reference article:Cylindrical shaft


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