1. Temperature conditions at the time of measurement
The ambient temperature of the measurement is set at 20℃, and the temperature of the imported bearings, measuring 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 will take hours or even days to achieve such a balance.
To get correct measurements, foreign countries rely on mechanisation to avoid manual contact with the objects, or to operate with heat-resistant gloves.
2. Provision of measurement area
For the measurement of the inner diameter or outer diameter of the imported bearing, it is stipulated in China to measure within the area with the maximum chamfering coordinates on each side away from the southern end of the ring, while in foreign countries, it is usually required to measure within the area with the maximum chamfering coordinates on each side away from the ring.
3. Specification of size base
When using comparative measurement method to carry out measurement pair of dimension tolerance of import bearing, the specified quantity block or standard parts shall be taken as the dimension datum of comparative measurement. The measurement block shall conform to the provisions of standard JB/T1078 "Measurement Block", and the standard parts shall conform to the provisions of the competent department of the manufacturer.
4. Regulations on measuring instruments
The instrument used in the measurement must be calibrated and have a precision and amplification ratio appropriate to the bearing being tested.
5. Allowable measurement error
In principle, the measurement error is allowed to be less than 10% of the tolerance.
6. Head radius and gauge pressure
In order to reduce the measurement error, it is necessary to try to reduce the pressure-measurement force of the gauge and increase the radius of curvature of the probe within the possible range.
When measuring the inner diameter and outer diameter of the inlet bearing, the measuring force and the radius of curvature of the probe can be selected by reference.
7. Mandrel used for measurement
When measuring Kia, Kea and Sd of imported bearings, the taper mandrel used for imported bearings with cylindrical holes is stipulated as 1/5000 l / 10000 in principle, and the basic taper of the taper mandrel used for uranium bearing with tapered holes is stipulated as 1/12.
8. Provisions for measuring loads
When measuring Kia,Kea, Sia,Sea and other items, the necessary measurement load should be applied to make the rolling body and ring in normal contact position to obtain stable measurement value.
9. Provision for measuring datum level
For the general rolling inlet bearing, the non-printing end face of the ring is taken as the datum plane during the measurement; for the angular contact ball inlet bearing and tapered roller inlet bearing, the end face bearing thrust load is taken as the datum plane.
The installation method of imported bearing varies with bearing structure, fit and conditions. Generally, the inner ring needs interference fit because it is mostly axial rotation.Cylindrical bore bearings, multi-purpose press or multi-purpose heat loading.In the case of taper holes, install directly on the taper shaft, or with sleeve installation.When installing to the housing, there are generally many clearance fits, and the outer ring has interference, which is usually pressed in by a press, or there is also a cold-shrink fit method for installation after cooling.When dry ice is used as coolant, the moisture in the air will condense on the surface of the inlet bearing in case of cold shrinkage.Therefore, appropriate anti-rust measures are needed.
Usually shaft and bearing box almost to continue to use, import bearings are often to continue to use.Therefore, the structure should be designed to remove the bearings without damaging the bearings, shafts, bearing boxes and other parts, and appropriate removal tools should be available.When removing the ring with static fit, only the pull force can be added to the ring, and the ring cannot be drawn by the rolling body.
1. Clean the dust on the fan to avoid further dust entering the inlet bearing during installation;
2. Tear off the sticker of the import bearing seal and remove the pin on the shaft;
3. Wipe the residual oil in the imported bearing with clean paper or soft cloth, and then wipe the shaft rod;
4. Add a little butter into the import bearing, the principle is less than more so as not to seriously affect the speed;
5. Then cut out the aluminum skin of the can and cut a round piece as big as the outer diameter of the pin of the import bearing. Cut a small hole in the middle that can just pass through the shaft rod and pad it between the import bearing and the pin to reduce the axial movement and parallel movement distance of the import bearing.If the clearance is large, it is necessary to pad several thickening to make the front and rear moving distance of the bearing below 0.5mm;
6, seal the oil well, add a little butter, finally put the fan back to the graphics card.Try plugging it in, and you'll find it's much quieter, and it'll last for at least two years.But the need to remind, although the voice is smaller, but because the manual precision is limited, the speed will drop a little bit.