The temperature bearing value of high temperature bearings is mainly determined by the material of bearings. Different varieties and materials have different high temperature resistance. First, the temperature grade of high temperature bearings The temperature grades of high temperature bearings are as follows: (1), 0~600 high temperature bearings The general temperature grades are divided into 200, 300, 400, 500 and 600, and the common temperature grades are 300 and 500. (2), 600~800 high temperature bearings This kind of high temperature bearing is generally divided into two kinds, full high temperature steel high temperature bearing and ceramic mixed high temperature bearing. (3), 800-1200 high temperature bearings. This kind of bearings generally use silicon nitride ceramics as raw materials to replace the high temperature environment that steel is difficult to reach. Temperature classification of high temperature bearings The temperature classification of high temperature bearings is as follows: 1, ordinary bearing steel high temperature resistance: 150-200℃ (its structure is full rolling body, short service life, high maintenance cost) 2, high temperature alloy steel: 300-500℃ (its structure includes cage, full rolling body two kinds; Service life more than one year, recommended) 3, silicon nitride ceramic rolling body: 800-1200℃ (its structure full rolling body, long service life, high cost) if your use environment does not exceed 500℃ can take the second material. Adopt high temperature bearing mode according to the actual application environment to choose, such as: the environment is bad, high speed must be used with cage, sealing ring, imported high temperature grease. Two, the structure classification of high temperature bearings 2.1. Conventional bearing structure Because there is no cage for high temperature bearings of this kind of structure, the increased number of rolling bodies greatly increases the bearing's characteristics of heavy load and low speed, and the service life is longer. The temperature range of high temperature bearings is 0-800. But the deficiency is that the limit speed of this kind of high temperature bearing is low, generally not more than 100r/min, and the bearing with larger inner diameter will be lower. The categories that meet the requirements of this type of bearing are: deep groove ball bearings, self-aligning ball bearings, single row cylindrical roller bearings and outer spherical ball bearings. It should be noted that the high speed mentioned here is not that the bearing can reach a high limit speed, but that the "full loaded rolling body high temperature bearing", affected by bearing clearance and other factors, can generally reach 70% to 80% of the national standard limit speed of ordinary bearings. This kind of bearing can bear the temperature range of less than 600. 2.2. All-ceramic or mixed ceramic bearings Ceramic bearing Ceramic bearings can generally withstand very high temperature, the limit temperature can reach 1200. But it can be achieved only with ceramic cages, graphite cages or no cages. The temperature resistance of mixed ceramic bearings (steel inner and outer rings and ceramic balls) is lower. If it is matched with steel cages, it can only reach the limit temperature of 600, but because of the high hardness and light weight of ceramic balls. Bearing and shaft, bearing and hole tolerance fit Doing non-standard for so long, the tolerance coordination between bearings and shafts, as well as the tolerance coordination between bearings and holes, has always been able to achieve functions with small clearance coordination, and it is easy to install and disassemble. But some parts still need to have a certain precision. fit tolerance refers to the sum of tolerances of holes and axes that constitute a fit. It is the amount of change allowed from clearance to interference. The size and position of the tolerance band of the hole and shaft constitute the fit tolerance. The fit tolerance of hole and shaft indicates the fit precision of hole and shaft. The size and position of the hole and shaft fit tolerance zone indicate the fit precision and fit property of hole and shaft. Choice of tolerance grade The tolerance grade of the shaft or bearing seat hole fitted with the bearing is related to the bearing accuracy. The shaft fitted with a P0 class precision bearing has a tolerance class of IT6 and a bearing seat hole of IT7. For occasions with high requirements for rotation accuracy and smoothness of operation (such as motors, etc.), the shaft should be selected as IT5 and the bearing seat hole as IT6. Choice of tolerance zone The equivalent radial load P is divided into "light", "normal" and "heavy" loads, and the relationship between it and the rated dynamic load C of bearings is as follows: light load P≤0.06C normal load 0.06C < P≤ 0.12C heavy load 0.12C < P 1) Shaft tolerance zone Please refer to the corresponding tolerance band table for the axis on which the centripetal and angular contact bearings are installed. For most occasions, when the shaft rotates and the direction of radial load is unchanged, that is, when the bearing inner ring rotates relative to the direction of load, transition or interference fit should be selected. When the axial shaft is stationary and the direction of radial load is unchanged, that is, the bearing inner ring is static relative to the direction of load, transition or small clearance can be selected (too large clearance is not allowed). 2) Shell hole tolerance zone Install the tolerance bands for the housing holes of the centripetal and angular contact bearings by referring to the corresponding tolerance band table. When choosing, pay attention to the outer ring that swings or rotates in the direction of load, and avoid clearance fit. The size of the equivalent radial load also affects the fit selection of the outer ring. 3) Selection of bearing seat structure form Unless there is a special need, the bearing seat of the rolling bearing is generally integrated structure, split bearing seat is only used when the assembly is difficult, or the advantages of convenient assembly become the main consideration, but it cannot be applied to tight fit or more precise fit, such as K7 and tighter fit than K7, and such as the tolerance class IT6 or more precise seat hole. Split bearing seat shall not be used. Standard for fit tolerance of bearings and shafts (1) When the bearing inner diameter tolerance zone is matched with the shaft tolerance zone, the tolerance code of the original transition fit will become over-win fit in the general base hole system, such as k5, k6, m5, m6, n6, etc., but the over-win amount is not large; When the bearing inner diameter tolerance is matched with h5, h6, g5, g6, etc., it is no longer a clearance but an over-win match. (2) Bearing outer diameter tolerance belt is also a special tolerance belt because the tolerance value is different from the general reference shaft. In most cases, the outer ring is fixed in the housing hole, and the structure requirements of some bearing components need to be adjusted. The fit should not be too tight, and it is often matched with H6, H7, J6, J7, Js6, Js7 and so on. Attached: Under normal circumstances, the axis is generally marked 0 ~ +0. 005, if you don't do it very often, is plus 0. 005 to +0. 01 interference fit is OK, if you want to often disassemble and assemble is the transition fit. We also have to take into account the thermal expansion of the shaft material itself when rotating, so the bigger the bearing, the better is -0. The clearance fit between 005 and 0 should not exceed 0. 01 clearance fit. The other one is moving ring interference, static ring gap. Bearing fit is generally a transition fit, but interference fit is optional in special cases, but rarely. Because the bearing and shaft fit is the bearing inner ring and shaft fit, the base hole system is used. Originally, the bearing should be completely zero-oriented, and we can think so in actual use. However, in order to prevent the inner ring rolling when the bearing inner ring matches the minimum limit size of the shaft, which will damage the surface of the shaft, Therefore, our bearing inner rings have 0 to a few μs of lower bias tolerance to ensure that the inner ring does not rotate, so the bearing generally chooses the transition fit, even the choice of transition fit can not exceed the interference of 3 wires. Generally, the precision level of coordination is 6. Sometimes, it depends on the material and processing technology. Theoretically, the 7 level is a little biased to the bottom, and the 5 level coordination will be used to grind. I generally choose: bearing inner ring with shaft selected k6 Bearing outer ring with hole selected K6 or K7.
What material is the high temperature bearing made of, and how many degrees is it capable of?
The temperature bearing value of high temperature bearings is mainly determined by the material of bearings. Different varieties and materials have different high temperature resistance. First, the temperature grade of high temperature bearings The temperature grades of high temperature bearings are as follows: (1), 0~600 high temperature bearings The general temperature grades are divided into 200, 300, 400, 500 and 600, and the common temperature grades are 300 and 500. (2), 600~800 high temperature bearings This kind of high temperature bearing is generally divided into two kinds, full high temperature steel high temperature bearing and ceramic mixed high temperature bearing. (3), 800-1200 high temperature bearings. This kind of bearings generally use silicon nitride ceramics as raw materials to replace the high temperature environment that steel is difficult to reach. Temperature classification of high temperature bearings The temperature classification of high temperature bearings is as follows: 1, ordinary bearing steel high temperature resistance: 150-200℃ (its structure is full rolling body, short service life, high maintenance cost) 2, high temperature alloy steel: 300-500℃ (its structure includes cage, full rolling body two kinds; Service life more than one year, recommended) 3, silicon nitride ceramic rolling body: 800-1200℃ (its structure full rolling body, long service life, high cost) if your use environment does not exceed 500℃ can take the second material. Adopt high temperature bearing mode according to the actual application environment to choose, such as: the environment is bad, high speed must be used with cage, sealing ring, imported high temperature grease. Two, the structure classification of high temperature bearings 2.1. Conventional bearing structure Because there is no cage for high temperature bearings of this kind of structure, the increased number of rolling bodies greatly increases the bearing's characteristics of heavy load and low speed, and the service life is longer. The temperature range of high temperature bearings is 0-800. But the deficiency is that the limit speed of this kind of high temperature bearing is low, generally not more than 100r/min, and the bearing with larger inner diameter will be lower. The categories that meet the requirements of this type of bearing are: deep groove ball bearings, self-aligning ball bearings, single row cylindrical roller bearings and outer spherical ball bearings. It should be noted that the high speed mentioned here is not that the bearing can reach a high limit speed, but that the "full loaded rolling body high temperature bearing", affected by bearing clearance and other factors, can generally reach 70% to 80% of the national standard limit speed of ordinary bearings. This kind of bearing can bear the temperature range of less than 600. 2.2. All-ceramic or mixed ceramic bearings Ceramic bearing Ceramic bearings can generally withstand very high temperature, the limit temperature can reach 1200. But it can be achieved only with ceramic cages, graphite cages or no cages. The temperature resistance of mixed ceramic bearings (steel inner and outer rings and ceramic balls) is lower. If it is matched with steel cages, it can only reach the limit temperature of 600, but because of the high hardness and light weight of ceramic balls. Bearing and shaft, bearing and hole tolerance fit Doing non-standard for so long, the tolerance coordination between bearings and shafts, as well as the tolerance coordination between bearings and holes, has always been able to achieve functions with small clearance coordination, and it is easy to install and disassemble. But some parts still need to have a certain precision. fit tolerance refers to the sum of tolerances of holes and axes that constitute a fit. It is the amount of change allowed from clearance to interference. The size and position of the tolerance band of the hole and shaft constitute the fit tolerance. The fit tolerance of hole and shaft indicates the fit precision of hole and shaft. The size and position of the hole and shaft fit tolerance zone indicate the fit precision and fit property of hole and shaft. Choice of tolerance grade The tolerance grade of the shaft or bearing seat hole fitted with the bearing is related to the bearing accuracy. The shaft fitted with a P0 class precision bearing has a tolerance class of IT6 and a bearing seat hole of IT7. For occasions with high requirements for rotation accuracy and smoothness of operation (such as motors, etc.), the shaft should be selected as IT5 and the bearing seat hole as IT6. Choice of tolerance zone The equivalent radial load P is divided into "light", "normal" and "heavy" loads, and the relationship between it and the rated dynamic load C of bearings is as follows: light load P≤0.06C normal load 0.06C < P≤ 0.12C heavy load 0.12C < P 1) Shaft tolerance zone Please refer to the corresponding tolerance band table for the axis on which the centripetal and angular contact bearings are installed. For most occasions, when the shaft rotates and the direction of radial load is unchanged, that is, when the bearing inner ring rotates relative to the direction of load, transition or interference fit should be selected. When the axial shaft is stationary and the direction of radial load is unchanged, that is, the bearing inner ring is static relative to the direction of load, transition or small clearance can be selected (too large clearance is not allowed). 2) Shell hole tolerance zone Install the tolerance bands for the housing holes of the centripetal and angular contact bearings by referring to the corresponding tolerance band table. When choosing, pay attention to the outer ring that swings or rotates in the direction of load, and avoid clearance fit. The size of the equivalent radial load also affects the fit selection of the outer ring. 3) Selection of bearing seat structure form Unless there is a special need, the bearing seat of the rolling bearing is generally integrated structure, split bearing seat is only used when the assembly is difficult, or the advantages of convenient assembly become the main consideration, but it cannot be applied to tight fit or more precise fit, such as K7 and tighter fit than K7, and such as the tolerance class IT6 or more precise seat hole. Split bearing seat shall not be used. Standard for fit tolerance of bearings and shafts (1) When the bearing inner diameter tolerance zone is matched with the shaft tolerance zone, the tolerance code of the original transition fit will become over-win fit in the general base hole system, such as k5, k6, m5, m6, n6, etc., but the over-win amount is not large; When the bearing inner diameter tolerance is matched with h5, h6, g5, g6, etc., it is no longer a clearance but an over-win match. (2) Bearing outer diameter tolerance belt is also a special tolerance belt because the tolerance value is different from the general reference shaft. In most cases, the outer ring is fixed in the housing hole, and the structure requirements of some bearing components need to be adjusted. The fit should not be too tight, and it is often matched with H6, H7, J6, J7, Js6, Js7 and so on. Attached: Under normal circumstances, the axis is generally marked 0 ~ +0. 005, if you don't do it very often, is plus 0. 005 to +0. 01 interference fit is OK, if you want to often disassemble and assemble is the transition fit. We also have to take into account the thermal expansion of the shaft material itself when rotating, so the bigger the bearing, the better is -0. The clearance fit between 005 and 0 should not exceed 0. 01 clearance fit. The other one is moving ring interference, static ring gap. Bearing fit is generally a transition fit, but interference fit is optional in special cases, but rarely. Because the bearing and shaft fit is the bearing inner ring and shaft fit, the base hole system is used. Originally, the bearing should be completely zero-oriented, and we can think so in actual use. However, in order to prevent the inner ring rolling when the bearing inner ring matches the minimum limit size of the shaft, which will damage the surface of the shaft, Therefore, our bearing inner rings have 0 to a few μs of lower bias tolerance to ensure that the inner ring does not rotate, so the bearing generally chooses the transition fit, even the choice of transition fit can not exceed the interference of 3 wires. Generally, the precision level of coordination is 6. Sometimes, it depends on the material and processing technology. Theoretically, the 7 level is a little biased to the bottom, and the 5 level coordination will be used to grind. I generally choose: bearing inner ring with shaft selected k6 Bearing outer ring with hole selected K6 or K7.