What is the tolerance of the bore of the machining bearing file?

When the bearing bore tolerance zone and the shaft tolerance zone form a fit, the tolerance code of the original transition fit in the general base hole system will be changed to a winning fit, such as K5, K6, M5, M6, N6, etc., but the winning amount is not large; When the bearing bore tolerance generation is matched with H5, H6, G5, G6, etc., it is not a clearance but a winning fit. Bearing outer diameter tolerance zone because the tolerance value is different from the general reference shaft, is also a special tolerance zone, in most cases, the outer ring is installed in the shell hole is fixed, some bearing components structure requirements need to be adjusted, its fit should not be too tight, often with H6, H7, J6, J7, JS6, JS7 and so on. In general, the shaft is generally marked with 0 If it is not often disassembled, it is .

01's interference fit is OK, if you want to often disassemble and assemble it is a transition fit. We also need to take into account the thermal expansion of the shaft material itself when rotating, so the larger the bearing, the better the clearance fit, and the maximum should not exceed 0. The principle of selecting the tolerance grade of the extended data is to choose the lowest tolerance grade as possible on the premise of meeting the requirements of the use of the part.

The precision requirements should be in harmony with the production possibilities, i.e. the use of reasonable machining techniques, assembly processes and existing equipment. However, if necessary, it is necessary to take measures to improve the accuracy of the equipment and improve the process to ensure the accuracy of the product. It is extremely important to select the appropriate tolerance class for the fit size.

Because in many cases, it will determine the performance, service life and reliability of the matching parts, and at the same time determine the manufacturing cost and production efficiency of the parts. (1) The selection of tolerance grade should first ensure the use requirements. (2) When selecting the tolerance grade, it is necessary not only to meet the design requirements, but also to consider the possibility and economy of the process.

Choosing the best machining accuracy is a very complex technical and economic problem. It takes into account not only the cost of processing, but also the increased assembly cost due to the improvement of machining accuracy, as well as the impact of precision on the performance of the product and economic indicators (reliability, life, fuel consumption, etc.). (3) In machinery manufacturing, the regulation of tolerance grade is based on ensuring the accuracy of the machine and the interchangeability of parts, and the economy of the manufacturing machine.

That is to say, as long as the low precision can ensure the function and accuracy of the machine, do not ask too high for the accuracy of the parts. That would increase the cost of manufacturing. Specifically, the tolerance level should be determined according to the type of machine and the use of a certain part, including dimensional tolerance and fit tolerance.

The bore size is the tolerance range of the bearing block, and the basic size is minus 2 to 3 wires.

The bearing tolerance is generally H7 in the inner ring and H6 in the outer ring.

In general, the tolerance of the bore of the inner ring of the standard bearing is h7, and the tolerance of the outer ring of the bearing is h6; The fit between the inner ring of the bearing and the shaft is H7 H7 or H7 JS6 (base bore system), and the fit between the outer ring of the bearing and the bore is H7 H6 or JS7 H6 (base shaft system).

The fit between the linear bearing and the guide shaft is H7 G6 (base shaft system), and the fit between the linear bearing bushing and the mounting hole is H7 H7 (base shaft system). Note: Slightly different fit tolerances are applied when positioning datums are different.

How to determine the tolerance class of the shaft.

1. Take the bearing of ordinary grade (P0 grade) 6308 as the key example:

It can be found in the bearing tolerance table, the outer ring tolerance of the bearing is: upper difference: 0 lower difference is:.

2. According to the rotation mode and bearing mode of the bearing

The outer ring is generally fixed relative to the inner ring, and the bearing is fixed bearing, not the main bearing. According to these contents, it can be found in the recommended fit table of the housing hole: the bearing with the bearing seat is recommended to be the tolerance zone

Upper tolerance +, lower difference 0The description is a gap fit, the maximum amount of clearance: , the minimum amount of clearance 0.

3. The fit between the inner ring of the bearing and the shaft:

The tolerance of the inner ring of the 6308 bearing is: the upper difference is 0, and the lower difference is based on: the inner ring rotation load, the ordinary load, and the matching tolerance zone of the recommended shaft is: m5, the upper difference: +, the lower difference: description: the maximum clearance is, the maximum interference. <>

The tolerance standard of the shaft is: to 0012mm.

The matching of bearings is generally used: the outer circle of the bearing is matched according to the base shaft system, and most of them are H6 H7 tolerances. H32 = 0 to -0 mm for 35 and H7 = 0 to 0016.

Then when mating with the outer circle of the bearing, the K7 H6 of 32 and 35 can be used, and the tolerance of the outer hole is: to. The inner bore of the bearing is matched according to the bore shaft system, and most of them are H6 H7 tolerances.

12 and 15 for h6 = 0 to, h7 = 0 to.

Then the H7 K6 of 12 and 15 can be used for matching with the bearing bore, and the tolerance of the shaft is: the meaning of the bearing tolerance standard

Bearing tolerance standards create consistency in bearing manufacturing and ensure a uniform product.

Bearing Standard Process:

In the United States, bearing standard tolerances are submitted by the American Bearing Manufacturers Association (ABMA) to the body that also approves these standards. These standards are created and overseen by ABEC, an organization owned by ABMA. ABEC and ABMA carry the weight of the industry and are the main players in the bearing tolerances in the United States.

All bearing standards organizations, including DIN and ISO, work together to achieve the common goal of creating equivalent bearing tolerances on a global scale. This is achieved when users can trust bearing standards and can successfully harmonize the use of precision bearings in many industries around the world. <>

The fit tolerance of the bearing bore is the sum of the tolerances of the bore and shaft that make up the fit.

It is the amount of movement that allows for a gap or interference. The size of the tolerance zone and the position of the tolerance zone of the bore and shaft form the fit tolerance. Bearing Tolerance Fit Principle:

If the moving coil is interference, the inner ring of the static ring clearance bearing should be dismantled and transitioned. Install the tolerances h7, g7, k7 in the hole of the outer ring of the bearing.

Selection of tolerance zones:

1. The equivalent radial load p is divided into light, normal and heavy load, and the relationship between it and the rated dynamic load c of the bearing is: light load p normal load.

2. The tolerance zone of the shaft with the tolerance zone of the shaft where the radial bearing and the angular contact bearing are installed refer to the corresponding tolerance zone table.

3. In most cases, the shaft rotates and the radial load direction remains unchanged, that is, when the bearing inner ring rotates relative to the direction of load dissipation, the transition or interference fit should generally be selected.

4. When the stationary shaft and the radial load direction remain unchanged, that is, when the inner ring of the bearing is stationary relative to the load direction, you can choose transition or small clearance fit (too large clearance is not allowed).

5. The housing hole tolerance zone is installed with the housing hole tolerance zone of the radial bearing and the angular contact bearing, refer to the corresponding tolerance zone table. When selecting, pay attention to the gap fit for the outer ring that swings or rotates in the direction of the load, and should avoid clearance fits.

6. Unless there is a special need, the integral structure is generally adopted, and the split bearing seat is only difficult to assemble. <>

1. Take the bearing of ordinary grade (P0 grade) 6308 as an example

It can be found in the bearing tolerance table, the outer ring tolerance of the bearing is: upper difference: 0 lower difference is:.

2. According to the rotation mode and bearing mode of the bearing

The outer ring is generally fixed relative to the inner ring, and the bearing is fixed bearing, not the main bearing. According to these contents, it can be found in the recommended fitting table of the housing bore: for bearings using bearing housings, the recommended housing bore tolerance zone is the tolerance zone:

Upper tolerance +, lower difference 0The description is a gap fit, the maximum amount of clearance: , the minimum amount of clearance 0.

3. The fit between the inner ring of the bearing and the shaft: the tolerance of the inner ring of the 6308 bearing is: the upper difference is 0, and the lower difference is based on:

Note: The maximum clearance is the maximum interference. Pie chain.

4. To sum up: to determine the fit between the bearing and the shaft and the shell hole, you can easily get it according to the rotation situation, load size and accuracy level of the bearing. Different combinations are required, which can also be adjusted according to the list.