Installation Form And Stress Analysis Of Linear Guide Bearing
Installation Form And Stress Analysis Of Linear Guide Bearing
2021年12月20日
Induction Heating For Bearing Installation Of Pipe Opener
Induction Heating For Bearing Installation Of Pipe Opener
2021年12月20日

Final Finishing Steps Of Nsk Precision Bearing

Nsk Precision Bearing

Finishing steps after NSK precision bearing

Under certain load, the number of revolutions or hours before pitting corrosion of NSK precision bearing is called bearing life.

Due to different manufacturing accuracy and material uniformity, even if the same batch of bearings with the same material and size are used under the same working conditions, their service life is also different. When the statistical life is 1 unit, the relative life of drunk length is 4 units, the drunk short is 0.1-0.2 units, and the ratio of drunk length to drunk short life is 20-40 times.

In order to determine the life standard of NSK precision bearing,

the bearing life and reliability are linked. The same batch of bearings of the same specification (model, material and process) are used under the same working conditions. 90% of the bearings do not produce pitting corrosion. The number of revolutions or hours experienced is called the rated life of the bearing.

In order to compare the bearing capacity against pitting corrosion, the large load that the bearing can bear when the rated life is 1 million RPM (106) is the basic dynamic load, expressed in C.

Final Finishing Steps Of Nsk Precision Bearing

In other words, the reliability of bearing without pitting failure is 90% at NSK precision bearing rated dynamic load C and 1 million RPM (106). The greater the value of C, the higher the bearing capacity.

When the grindstone surface is in contact with the rough raceway surface, due to the small contact area and large stress per unit area, the “reverse cutting” effect of the bearing workpiece will be affected under a certain pressure, and some abrasive particles on the grindstone surface will fall off, resulting in new wear and debris.

At the same time, the bumps on the surface of bearing workpiece are quickly cut, and the bumps and grinding metamorphic layer are removed by cutting and reverse cutting. This stage is called the cutting stage, in which most of the remaining metal is removed.

With the continuous processing,

the surface of NSK precision bearing workpiece is gradually ground. At this time, the contact area between the grindstone and the workpiece surface increases, the pressure per unit area decreases, the cutting degree decreases and the cutting capacity decreases.

At the same time, the pores on the surface of the grindstone are blocked and in a semi cutting state. This stage is called the half cutting stage of bearing finishing. In the half cutting stage, the cutting marks on the surface of the bearing workpiece become shallow and appear dark luster.

This is a drunk step in the Superfinishing of NSK precision bearings. With the gradual leveling of the workpiece surface, the contact area between the grindstone and the workpiece surface further increases. The grindstone surface and the bearing workpiece surface are gradually separated by the lubricating oil film.

The pressure per unit area is very small and the cutting effect is reduced. When drunk, the cutting will stop automatically. This stage is called the end stage. In the finishing stage, there is no cutting trace on the workpiece surface, and the bearing presents a bright finished luster.

Induction heating for bearing installation of pipe opener

When installing the drill pipe and bearing of the pipe opener, pay attention to measuring the machining precision of the bearing and drill pipe. If it is within the normal range, it can be installed by heating and liquid nitrogen cooling. Violent installation and disassembly are strictly prohibited.

There are many heating methods, including electric plate heating, electric furnace heating, electric bulb heating, oil tank heating and sensory heating. Induction heating is an environmentally friendly and temperature controllable way. The following is a brief introduction:

1. Principle of induction heating:

Compared with the transformer in physics, the working principle of sensory heating is to install a primary coil with more turns and a secondary coil with less turns on the same iron core.

The input to output voltage ratio is equal to the ratio of coil turns, while the energy remains unchanged. Therefore, the secondary coil generates a large current at low voltage. For induction heating equipment, the main shaft bearing of the pipe opener is a short-circuit single turn secondary coil, which passes through large current under the condition of low AC voltage, resulting in great heat.

The heater itself and the yoke are kept at room temperature. Because this heating method can induce current, the bearing will be magnetized. The latter step is to demagnetize the bearing so that the pipe opener will not absorb the metal debris during pipe opening during operation. Therefore, the demagnetization process shall be carried out for the main shaft bearing of the pressurized pipe opener after induction heating.