1. Regulations of the measurement area
For the measurement of the inner diameter or outer diameter of agricultural ball bearings, it is stipulated in China that the measurement should be performed within the area where each of the southern end faces of the ferrule is a chamfer coordinate, while in foreign countries, it is stipulated that the area away from both ends of the ferrule is twice the chamfer coordinate. measured within.
2. Specifications of dimensional benchmarks
When using the comparative measurement method to measure the dimensional tolerance of agricultural ball bearings, the measuring block or the standard part is specified as the dimensional reference for the comparative measurement, and the measuring block must meet the requirements of the standard JB/T1078 "gauge block", and the standard part must meet the manufacturer's requirements. regulations of the competent authority.
3. Temperature conditions during measurement
The ambient temperature during measurement is specified as 20°C, in which the temperature of the agricultural ball bearings, gauge blocks, standard parts, and measuring instruments must be the same. The above method of placing them on the same metal plate can quickly achieve the necessary temperature balance, otherwise, it will take hours or even days to reach such a balance.
4. Allowable measurement error
In principle, the measurement error can be allowed to be less than 10% of the tolerance.
5. Probe radius and gauge pressure
To reduce the measurement error, it is necessary to reduce the pressure-measuring force of the measuring table and increase the radius of curvature of the probe within the possible range.
When measuring the inner and outer diameters of agricultural ball bearings, the measuring force and the radius of curvature of the probe can be selected by reference.
6. Regulations for measuring instruments
The instruments used for the measurement must be calibrated and have the correct accuracy and magnification ratio for the agricultural ball bearings being measured.
7. Measure the mandrel used
When measuring items such as Kia, Kea, and Sd of agricultural ball bearings, for cylindrical bore agricultural ball bearings, the taper of the tapered mandrel used is in principle 1/5000-l/10000, and for tapered bore uranium bearings, the tapered mandrel used The basic taper is specified as 1/12.
8. Regulations for measuring datum planes
For general rolling agricultural ball bearings, the non-printing end face of the ferrule is taken as the reference plane for measurement, and for angular contact ball bearings and tapered roller agricultural ball bearings, the end face bearing the thrust load is taken as the reference plane.
9. Provisions for measuring loads
When measuring Kia, Kea and Sia, Sea, and other items, it is necessary to apply the necessary measurement load to make the rolling element and the ferrule in a normal contact position to obtain a stable measurement value.