What is the fit between the inner ring of the bearing and the journal? What is the fit between the o

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Under normal working conditions, the bearing and the shaft usually adopt a clearance fit, if the bearing runs at low speed, the shaft can choose H9; If the speed is higher, the shaft can be H8, H7; If it is told to run, the shaft can be selected H6However, the structure of this kind of product is relatively special, it is a self-aligning and contact seal, so the speed will not be too high when used. The matching of the bearing and the shaft adopts the base hole system, and the matching between the bearing and the shell adopts the base shaft system.

For rolling bearings, because they are standard parts, the GB T275-1993 standard stipulates that the fit between the inner ring of the bearing and the journal belongs to the base hole system, and the fit between the outer ring of the bearing and the housing hole belongs to the base shaft system.

Features of the inner diameter tolerance zone of the inner ring of rolling bearings:

The fit between the inner ring and the journal of the bearing is based on the base hole system, and the fit between the outer ring and the shell hole is based on the base shaft system. The upper deviation of the tolerance band is zero, and the lower deviation is negative.

Since the rolling bearing is a standard part, the fit between the inner ring and the journal is made of the base shaft system, and the fit between the outer ring and the bearing housing hole is the base shaft system. The tightness of the fit is determined according to the size, nature, and speed of the bearing working load.

The status quo of the industry. China's bearing manufacturing industry production and marketing demand and transformation and upgrading analysis report" data show that 2009-2013 China's bearing manufacturing industry industrial output value is increasing year by year. In 2013, the industry achieved a total industrial output value of 100 million yuan, a year-on-year increase.

The analysis of the data in the past five years found that the sales revenue of China's bearing manufacturing industry from 2009 to 2013 has also increased year by year. In 2013, the sales revenue was 100 million yuan, a year-on-year increase.

China's bearing industry is developing rapidly, bearing varieties from less to more, product quality and technical level from low to high, the scale of the industry from small to large, has formed a basic product category, production layout is more reasonable professional production system.

The inner diameter tolerance zone of the inner ring of the rolling bearing is made of base bore, because the bearing is a standard part!

It is generally an interference fit.

According to the direction and nature of the load acting on the bearing and which side of the inner and outer rings rotates, the load on each ring can be divided into rotational load, stationary load or non-directional load. The ferrule bearing the rotating load and the non-directional load should be in a static fit (interference fit), and the ferrule bearing the static load can be bent in a transitional fit or a dynamic fit (clearance fit).

When the bearing load is large or subjected to vibration and shock, its interference must be increased. When using hollow shafts, thin-walled bearing housings or light alloy and plastic bearing housings, it is also necessary to increase the interference excitation foci.

When it is required to maintain a high rotation, high-precision bearings must be used, and the dimensional accuracy of the shaft and bearing housing must be improved to avoid excessive interference. If the interference is too large, the geometrical accuracy of the shaft or bearing housing may affect the geometry of the bearing ring, which can compromise the rotational accuracy of the bearing.

The inner and outer rings of non-separable bearings (such as deep groove ball bearings) are statically fitted, so it is extremely inconvenient for the bearing to be installed and disassembled, and it is best to adopt a dynamic fit on one side of the inner and outer rings.

<> relative movement between the inner ring of the bearing and the shaft is not allowed.

The inner ring and shaft are actually made by means of an "interference fit."

Fastened together. No matter how large the tolerance is, it must also be an interference fit, and not only Sun Xian's mold shot allows for a gap fit. Therefore, to install the bearing on the shaft diameter, it is necessary to preheat the bearing before installation, and after cooling, the inner ring shrinks and is fastened with the bearing.

Kaijian, that is, the inner ring of the bearing and the shaft can only be used with an "interference fit".

The fitting clearance between the outer ring of the bearing and the bearing seat is on the left and right.

The standard limit value for the axial clearance of the hub bearing is that it cannot be exceeded. When installing the bearing, the coordination between the bearing and the shaft, the bearing and the bearing chamber will reduce the clearance of the bearing to a certain extent. There will be a clearance value.

In the process of use, when the bearing rotates, the internal clearance of the bearing will be reduced due to the temperature difference of the material. To achieve the most ideal life of the bearing, there must be a suitable clearance, clearance value = design clearance (factory clearance) early key - clearance reduction caused by inner ring fit - clearance reduction caused by outer ring fit plus or minus clearance reduction or increase due to temperature difference. The large clearance group is suitable for the inner and outer rings to fit a large amount of activity, or the temperature difference between the inner and outer rings is large, the deep groove ball bearing needs to bear a large axial load, or the self-alignment performance needs to be improved, or the ultimate speed of the bearing needs to be increased and the friction torque of the bearing needs to be reduced.

High-speed bearing outer diameter and housing mating clearance:

The outer diameter of the high-speed bearing and the matching clearance of the bearing seat are on the left and right, to match the clearance, the inner diameter of the bearing and the shaft seat are the same, if the bearing is too tight in the case of high speed, the heat is high, the bearing will be locked and damaged. Bearing: Bearing, which is used to determine the dynamic position of the rotating shaft and other parts relative to the beam, and plays a supporting or guiding role.

Its main function is to support the mechanical rotating body to reduce the friction coefficient of the mechanical load of the equipment during the transmission process. According to the different friction properties of moving elements, bearings can be divided into two categories: rolling bearings and sliding bearings. <>

Rolling bearing. The inner and outer rings are standard parts, the matching of the inner hole and the shaft adopts the base hole system, and the matching of the outer ring and the box hole adopts the base shaft system.

From the perspective of the working situation, the fit with the shaft needs to transmit torque, and the bearing bore and the shaft are required to rotate synchronously with high precision, so interference fit is used for this purpose.

That is, the coordination is more important. The fundamental deviation k in the interference fit can be selected.

The fit between the outer diameter of the bearing and the bore of the box mainly plays a supporting role, and both of them are fixed when working, and a transitional fit can be taken.

It can be slightly tighter, and the basic deviation j is generally used.

The annotation on the assembly drawing only needs to mark the deviation that needs to be processed, which can be abbreviated, as shown in the following figure.