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After checking that the burning is due to the bearing journal and bearing lubrication between the state of malignant transformation is part of the boundary lubrication condition caused by dry friction, therefore, to avoid NSK Bearings dry friction state generation is the key to solve their burning . In normal operation, the journal and there is a gap between the bearing and the presence of a film, a liquid lubricant, at this time the heat generated by friction is small, the heat away from the oil, in the normal operating temperature of the bearing. If direct contact with the journal bearings, form part of the dry friction condition, then a sharp increase in the friction power, a large amount of frictional heat, and oil from the bearing four weeks away the heat distribution, and much, heat build-up in the bearing, so that bearing temperature rise, when the temperature exceeds the melting point of the pad surface, the pad surface began to melt, until the bearing is fully burnt. Cause poor lubrication of the bearing of the main factors are:
(1) bearing bore concentricity or eccentric shaft journal runout tolerance
As can be seen from Figure 1, within the wheel of the vibration exciter eccentric shaft, the work speed in forward and reverse rotation of the eccentric shaft means and the amplitude will have a significant effect of the centrifugal force, the centrifugal force through the bearings at both ends to support and delivery, so both ends of the vibrating wheel bearing bore concentricity and runout eccentric shaft journal very demanding. If the geometric size tolerance, will result in the main journal and bearing gap is too small or no gap, the lubricant film thickness is not enough or no lubricant film.
(2) The eccentric shaft surface roughness tolerance
If the oil contains impurities such as metal wear debris, after a long run, will make the eccentric shaft roughness tolerance, there were many in the journal surface metal edge peaks, these peaks destroys metal edges between the journal and the bearing lubrication the integrity and continuity of the film, serious, large-area metal edge peaks will work directly with the friction caused by bush burning bush.
(3) poor quality lubricants
NSK Bearings poor working conditions, by the impact load was significantly affected, the use of poor quality oil (such as oxidation resistance, poor stability). Mix different grades of oil, or oil mixed with prolonged use excessive dust or the temperature is too high because of work and other factors make the oil deterioration, will be of working oil film bearings have a huge negative impact.
(4) oil viscosity selection of indicators is not clear
Vibrating wheel work, the running time of the oil quality decreases with growth gradually worse, the viscosity of the oil will decline, it should determine oil oil standards. Oil viscosity is an important indicator of the end of its life, calculated according to our analysis, when the kinematic viscosity of the oil fell to 8mm2 / s, the bearing clearance in the 0.24-0.28 range, the ratio of the thickness of the bearing λ = 0.967. Wheel due to vibration during operation of the eccentric shaft journal and the bearing surface running in operation, causes an increase in the film thickness ratio, in this state is still in mixed lubrication, and can still maintain a certain film thickness, will not burn bearings. So we scrapped standards for (HC-14 motor oil) viscosity drops to 9.5mm2 / s need to change the oil. According to this standard should be scrapped, periodic sampling was conducted in order to control the quality of the oil used.
(5) the original structure defects
Seen from Figure 1, the bearing lubrication, by means 8 AM stir oil, lubricating oil splashes along the tangent to the circumference AM device casing 7, and then reflection splash mist formed, by NSK Bearings mist penetration into the body. This Jijian lubrication is not sufficient. Moreover, the shaft and the bearing clearance of the lubricant oil path because there is no bearing can work without friction generated heat away, resulting in the bearing operating temperature, oil viscosity decreased, film thickness decreases.
| Product Model | Inside Diameter | Outside Diameter | Thickness |
| 7904CDB NSK | 20 | 37 | 9 |
| 7904A5DB NSK | 20 | 37 | 9 |