What are Bearing Pullers?

A bearing puller is a device that takes the inner bearing out of the bearing seat. It is a built-in bearing puller, which includes a mounting plate, a pull bolt and a through-bolt; there are no less than two pull bolts, each pull The bottom of the bolt has a pull claw that can hang the bottom of the built-in bearing. A fastening nut is installed on each tension bolt. There is no less than one long hole in the middle of the mounting plate. The width of the long hole is greater than the diameter of the tension bolt. The lower end of each tension bolt passes through the long hole and extends below the mounting plate, and the fastening nut can be caught on the mounting plate at the long hole; no less than two positioning nuts are fixed on the mounting plate outside the long hole .

A bearing puller is a device that takes the inner bearing out of the bearing seat. It is a built-in bearing puller, which includes a mounting plate, a pull bolt and a through-bolt; there are no less than two pull bolts, each pull The bottom of the bolt has a pull claw that can hang the bottom of the built-in bearing. A fastening nut is installed on each tension bolt. There is no less than one long hole in the middle of the mounting plate. The width of the long hole is greater than the diameter of the tension bolt. The lower end of each tension bolt passes through the long hole and extends below the mounting plate, and the fastening nut can be caught on the mounting plate at the long hole; no less than two positioning nuts are fixed on the mounting plate outside the long hole . The utility model has a reasonable and compact structure, which can quickly and easily remove graphite and silicon carbide bearings of different diameters and lengths, and it will not cause damage to the inner bearing during disassembly, thus greatly reducing the damage caused by the inner bearing damage. The increase in product cost has also greatly improved the work efficiency of dismantling inner bearings.

An axle bearing puller for an axle includes a pull sleeve, a guide post, and a guide block. The guide block passes through the guide post, and the guide post is fixed on the pull sleeve. The guide block has bolts in the same direction as the guide post. The utility model can easily pull out the inner bearing of the truck axle hub without damaging valuable parts such as the axle housing of the axle.

Axle hub inner bearing puller is characterized in that it includes pull sleeve, guide post and guide block, the guide block is threaded on the guide post, the guide post is fixed on the pull sleeve, and the guide block has bolts in the same direction as the guide post. ^[1]

Design of New Bearing Puller for Outer Rotor Motor

Because the structure of the outer rotor motor is completely different from that of ordinary motors, there are the following difficulties in the process of motor inspection and maintenance.

(1) The incoming wire of the motor goes out from the center of the shaft, and the central support point of the puller cannot directly abut the shaft center. If the support point is supported at the boundary of the shaft, due to the force, it will slide off the surface of the shaft, which cannot provide sufficient force for the puller.

(2) The gap between the motor bearing and the coil is extremely narrow. Ordinary bearing pullers cannot be inserted. If the size is too large, the coil will be damaged. If the size is too small, the bearing will not catch.

The above two reasons make the maintenance of the outer rotor motor extremely difficult. Each time the outer rotor motor is inspected and repaired, it will take a lot of time to disassemble the bearing and cause damage to the coil.

Original disassembly method:

(1) For the problem that the incoming cable goes out of the center of the shaft, a Y -shaped member is needed to support the end face of the shaft, and the upper side of the member is supported by a metal plate. When such a method is operated, due to the imbalance of the force when the screw rotates down, the component will be squeezed off the center line.

(2) For the problem that the puller arm of the bearing puller cannot extend into the rear side of the bearing, if the distance between the bearing and the coil is very small, use a wire or wire to bypass the end of the bearing to connect the puller beam to perform the pull operation. Due to the ductility of the material, this method will cause the bearing to be unbalanced and damage the motor shaft.

The original method is time-consuming and labor-intensive, so it is urgent to design and manufacture a tool to easily dismantle the bearing to achieve the purpose of timely maintenance of the motor. Aiming at the two problems encountered in repairing the outer rotor motor, through careful study and discussion, it was decided to implement the following scheme:

(1) spacer design

First of all, for the problem that the load end of the puller cannot be supported at the motor inlet, the method of isolating the wire can be used. Due to the axial force, it needs to act directly on the axis, and the incoming cable can be bent. Therefore, a slotted spacer can be designed, on the one hand, the cable can be led out from the side in the direction of the slot, on the other hand, the support point of the puller can be directly supported on the surface of the spacer, and at the same time The contact surface of the machine is bored with a round groove slightly larger than the diameter of the shaft to hold the rotor shaft to ensure that it will not slip during use. After the measurement of the rotor shaft, the shape and size of the specific pad were determined.

(2) Design of tension arm

The gap between the motor bearing and the coil is extremely narrow, and the size of the ordinary bearing puller is too large to extend into

After discussion in the group, two design schemes were proposed, one for integrated design and the other for split design.

Integrated design

By measuring the distance between the outer wall of the bearing and the coil and the length that can be penetrated inside the bearing, a tension arm of the integrated bearing puller is designed.

The newly designed bearing puller can solve the problem that ordinary pullers cannot extend into the bearing. The outer rotor motors on the site all use 6 206 bearings with an inner diameter of 30 mm and an outer diameter of 62 mm. The length of the hook design is 13 mm. Not only will it not hurt the surface of the shaft, but it will be stuck in the bearing of the bearing sleeve.

How to use: The end of the tension arm is designed with a rotatable pull hook, which is fixed by the lower bolt. In use, rotate the pull hook to extend in the direction of the gap, then rotate 90 ° to the position where the bearing is hung, and then pull the bearing to pull the bearing down.

The material mechanical properties of the newly designed puller were tested. The material used in the design was 45 steel, and the unilateral tension arm was a rectangular parallelepiped with a length of 22mm, a width of 20mm, and a height of 140mm. Therefore, a cylindrical steel with a radius of 12mm was selected as the raw material . After the test, the tensile strength of the steel specimen is greater than 100 kN and far greater than 25 kN, so it fully meets the requirements. Shear stress also meets the requirements, so No. 45 steel is preferable.

During the mechanical test of the integrated version of the tension arm, the stress concentration at the contact edge of the cylinder with a radius of 7 mm at the bottom, fracture occurred, so the initial design solution was not feasible.

2. Split design scheme

As the performance of materials with a radius of more than 12mm fully meets the requirements, there is no need to replace the materials, and only the design scheme needs to be modified from the design method. The pull arm of the split puller is designed as two parts. In order to ensure material strength, an integrated design is selected at the lower side of the hook.

The integrated forming of the lower side hook ensures the strength, and the length of the hook is 13mm also ensures the rationality of the bearing bearing position. The upper and lower parts are docked first, and then fixed with 2 pins. Not only will the lower side hook not shake the wound coil, but also it is convenient to use and easy to disassemble.

Through mechanical performance tests, the tensile stress of the lower half of the tensile arm is greater than 40 kN, the flexural stress of the lower half of the tensile arm is greater than 35 kN, the tensile stress of the upper half of the tensile arm is greater than 40 kN, and the flexural strength of the upper half of the tensile arm is measured. The stress is> 20 kN, which far meets the design needs. At the same time, the upper half of the material is negligible due to bending stress, which can be considered to be only affected by the tensile force. At the same time, the thickness of the upper half is twice the thickness of the lower half, so it meets the design requirements more.

The last test is the shear performance test of the pin. The designed pin is a cylindrical steel with an inner diameter of 8mm, and the single material has a shear stress of more than 15kN. Since a set of bearing pullers share 4 pins, according to the principle of stress dispersion and sharing 25 kN of stress at the same time, each pin bears 7 kN is sufficient to achieve the function, so the pins also meet the design performance requirements.

The new design of the new bearing puller of the outer rotor motor is simple to process, easy to use, easy to assemble, and low in cost. The most important thing is that it can completely disassemble the bearing and meet the required performance and rationality. ^[2]

By using the newly designed bearing puller, huge benefits can be achieved. Take the induced draft fan of the ethylene plant cracking furnace as an example. If the motor is not repaired in time, the host will overheat the cracking furnace and stop the naphtha according to the single cracking furnace of the ethylene plant. 40 t / h, ethylene production 13 t / h, propane 7 t / h, butadiene 2 t / h. The price difference between ethylene is 3,000 yuan / ton, the price difference between propane is 2,000 yuan / ton, and butadiene is 20,000 yuan / ton. If a single cracking furnace is shut down, it will take 24 hours to resume production and it will cost 2.23 million yuan.

At the same time, the shutdown of the cracking furnace will cause the furnace pressure to change from negative to positive, causing the cracking furnace measuring instruments to be burned. In the October accident, nearly 35 thermocouples were burned at a time, each of which cost about 3,000 yuan, causing direct economic losses of more than 100,000 yuan. Calculated based on the average annual failure, so after using the new bearing puller, a total of more than 2.3 million yuan in benefits will be created each year, with obvious economic and social benefits ^[3] .