Routine inspections of rolling NSK bearing products must be carried out under the conditions specified in the national standards.
(1) Temperature conditions during measurement
The ambient temperature during measurement is specified as 20°C. The temperature of NSK bearings, gauge blocks, standard parts and measuring instruments must all be the same. The above method of putting them on the same metal plate can quickly achieve the necessary temperature balance. Otherwise, it will take several hours or even days to reach such a balance.
In order to obtain correct measurement results, foreign countries rely on the mechanization of measurement to avoid human hands touching these objects, or wearing heat-resistant gloves for operation.
(2) Regulations of measurement area
For the measurement of the inner diameter or outer diameter of NSK bearings, it is stipulated in China that the measurement is within the area of the largest chamfering coordinate away from the south end of the ring, while in foreign countries, it is often specified as the area leaving the two ends of the ring with twice the chamfering coordinate. Measure within.
(3) Dimension standard regulations
When using the comparative measurement method to measure the dimensional tolerances of NSK bearings, a gauge block or standard part is specified as the dimensional benchmark for comparison measurement. The gauge block must meet the requirements of the standard JB/T1078 "Gauge Block", and the standard part must conform to the manufacturer's supervisor Departmental regulations.
(4) Regulations for measuring instruments
The instrument used in the measurement must be calibrated and have the accuracy and amplification ratio that are compatible with the measured NSK bearing.
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(5) Allowable measurement error
In principle, the allowable measurement error is less than 10% of the tolerance.
(6) Probe radius and gauge pressure
In order to reduce the measurement error, it is necessary to reduce the pressure-measurement force of the gauge within the possible range and increase the radius of curvature of the probe.
When measuring the inner diameter and outer diameter of NSK bearings, the measuring force and the radius of curvature of the probe can be selected by reference.
(7) Mandrel used for measurement
When measuring the Kia, Kea and Sd items of NSK bearings, for cylindrical bore NSK bearings, the taper mandrel used is in principle specified as 1/5000-1l/10000. For uranium bearing with tapered bore, the basic taper mandrel used is The taper is specified as 1/12.
(8) Provisions for measuring load
When measuring Kia, Kea, Sia, Sea and other items, it is necessary to apply the necessary measurement load to make the rolling element and the ring in the normal contact position to obtain a stable measurement value.
(9) Provisions for the measurement reference surface
For general rolling NSK bearings, take the non-printed end surface of the ring as the reference surface during measurement, and take the end surface bearing the thrust load as the reference surface for angular contact ball NSK bearings and tapered roller NSK bearings.
When inspecting NSK bearings, never expose NSK bearings to pollutants or moisture. If work is interrupted, the machine should be covered with greased paper plastic sheet or similar material.
If the unmasked NSK bearing is cleaned without disassembly and inspection is possible, it should be cleaned with a white spirit with a coating brush, and then wiped dry with a lint-free cloth or blown with compressed air. Dry (be careful not to start rotating the NSK bearing assembly).
Use a small mirror and a probe similar to that used by dentists to inspect the track surface, retainer and beads of the NSK bearing. If the NSK bearing is not damaged, it should be relubricated according to the lubrication instructions provided by the machine manufacturer.