(1) Temperature conditions at the time of measurement
The ambient temperature during measurement is specified to be 20 ° C. The temperature of bearings, gauge blocks, standard parts and measuring instruments must be the same. The above method of placing them on the same metal plate can achieve the necessary temperature balance as quickly as possible. Otherwise, It takes hours or even days to reach this balance.
In order to get the correct measurement results, foreign countries rely on mechanization of measurement to avoid touching the objects by hand or wearing insulated gloves.
(2) Measurement area regulations
For the measurement of the inner or outer diameter of the bearing, the domestic regulations are measured within the area from the south end of the ferrule to each of the maximum chamfer coordinates, while the foreign regulations are specified to be within the area of the two sides of the ferrule that are twice the chamfering coordinates. measuring.
(3) Specification of the size standard
In the measurement of bearing dimensional tolerance by comparative measurement method, the specified mass or standard part is used as the dimensional reference for comparative measurement. The measuring block must meet the requirements of the standard JB/T1078 “Quantity Block”, and the standard parts must conform to the competent authority of the manufacturer. Provisions.
(4) Regulations of measuring instruments
The meter used for the measurement must be calibrated and have the accuracy and magnification ratio appropriate for the bearing being tested.
(5) Allowable measurement error
In principle, the measurement error can be tolerated below 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 and increase the radius of curvature of the probe to the extent possible.
When measuring the inner and outer diameters of the bearing, the measured force and the radius of curvature of the probe can be selected.
(7) The mandrel used for the measurement
In the case of measuring bearings such as Kia, Kea and Sd, the taper of the taper mandrel used for cylindrical bore bearings is in principle specified as 1/5000 to l/10000. For tapered bore uranium, the basic taper of the taper mandrel is specified. It is 1/12.
(8) Provisions for measuring load
When measuring Kia, Kea and Sia, Sea and other items, it is necessary to apply the necessary measurement load so that the rolling element and the ferrule are in normal contact position to obtain stable measurement values.
(9) Rules for measuring reference planes
For general rolling bearings, the non-printing end face of the ferrule is taken as the reference surface during the measurement. For the angular contact ball bearing and the tapered roller bearing, the end face subjected to the thrust load is taken as the reference surface.
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