JB/T 6520-1992 Calculation method for thrust bearings of steam turbines
Some standard content:
Mechanical Industry Standard of the People's Republic of China
JB/T 6520-1992
Calculation Method of Steam Turbine Thrust Bearing
Published on December 21, 1992
Implementation by the Ministry of Machinery and Electronics Industry of the People's Republic of China on May 1, 1993
Mechanical Industry Standard of the People's Republic of China
Calculation Method of Steam Turbine Thrust Bearing
Subject Content and Scope of Application
JB/T 6520-1992
This standard specifies fixed pad thrust bearings and point and line support tilting pad thrust bearings, and specifies the design calculation method, including parameter selection, performance curves and performance calculation procedures.
This standard applies to thrust bearings in steam turbines (laminar flow conditions, Newtonian fluid), and also to thrust bearings in other units under the same conditions.
Symbols and units
Symbols and units are shown in Table 1
Total area of pads
Area of each pad
Constants used in the calculation process
Radial width of pads
Constants used in the calculation process
Specific heat of lubricating oil
Average pad diameter
Inner diameter of pads
Outer diameter of pads
Thrust plate diameter
Pedestal support diameter
Shaft diameter
Radial offset of support
Circumferential offset of support
Pedestal inclination parameter
Thrust plate thicknessbZxz.net
Pedestal thickness
Oil film thickness
Oil film thickness at the pad outlet, for fixed pad thrust bearing h. =h.Minimum allowable oil film thickness when misalignment is taken into account Approval form of the Ministry of Machinery and Electronics Industry on December 21, 1992
J/(kg· C)
Implementation on May 1, 1993
Minimum oil film thickness
Minimum allowable oil film thickness
JB/T6520—1992
Continued Table 1
Oil film thickness on the inclined pitch line of the bearing
Stirring power consumption coefficient
Double length of the bearing at the average diameter
Total friction torque of the bearing
Dimensionless total friction torque of the bearing
Friction torque of each bearing
Dimensionless nanofriction torque of each bearing
Total Power consumption
Diaphragm power consumption of each tile
Dynamic power consumption
Thrust plate speed
Parker number
Lubricating oil pressure entering the tile
Average pressure ratio of tile
Average pressure ratio of tile starting
Average pressure ratio of tile platform starting
Required lubricating oil flow according to (t,), ts
Bearing oil inlet
Oil leakage inside and outside the bearing
Oil inlet of each tile
Infinite retraction oil volume of each tile
Each Internal and external oil leakage of each tile
Inner and outer oil leakage of each tileDiameter wall mark
Inner radius of tile
Outer radius of tile
Surface roughness value
Thrust plate Reynolds number R.=pnDE/ne
Radius of tile support
Temperature calculation coefficient
Temperature calculation coefficient
Equivalent temperature of oil film used for performance calculation
N·m/s
Oil supply temperature of lubricating oil
JB/T65201992| |tt||Continued Table 1
Temperature of lubricating oil entering the pad
Lubricating oil drain temperature
Permissible lubricating oil drain temperature
Lubricating oil temperature in the bearing box
Maximum pad temperature
Maximum permissible pad temperature
Total bearing load
Total bearing starting load
Load on each pad
Infinite steel load on each pad
Number of thrust pads
Temperature calculation coefficient
Pad height||tt| |Wear inclination angle
Mean temperature rise of lubricating oil
Dynamic viscosity of lubricating oil corresponding to ta
Dynamic viscosity of lubricating oil corresponding to t
Angular coordinates
Wear sector angle
Nodal position angle
Wear support angle
Lubricating oil thermal diffusion coefficient
Lubricating oil density
Drag coefficient
Angular velocity of thrust plate
3 Bearing structure type
3.1 The structure diagram of fixed bearing thrust bearing is shown in Figure 1JB/T65 201992
(a)Relative position of bearing parts
Direction of movement
(b)Cross-section and working diagram of thrust pad
Thrust plate
Support ring
Thrust plate
Platform or no platform
Oil film pressure distribution
(c)Arrangement of pads on support ring
Single pad
Platform outlet edge
Platform (or no platform)
Platform inlet edge
JB/T65201992| |tt||3.2 The structural diagram of the point and line supported tilting pad thrust bearing is shown in Figure 2W
Direction of movement
Thrust plate
Support ring
(a) Relative position of bearing parts
Inlet edge of pad
Oil film pressure distribution
Thrust plate
Pinpoint (point support or line support)
(b) Cross-section and working diagram of thrust pad
Pinpoint (or fulcrum line)
Thrust pad
(e) Arrangement of pad on support ring||t t||Direction of rotation of thrust plate
Line support
(d) Pad support parameters
Direction of rotation of thrust plate
Point support
JB/T6520-1992
Selection of parameters, materials and lubrication and related restriction criteria 4.1 Selection of parameters
4.1.1 Inner and outer diameters of pads
The shaft diameter d is usually determined according to the strength and degree requirements. The fillet radius, oil circuit and fit tolerance must be considered when selecting the inner diameter of the pad. Usually D,= (1.1～1.2)d is taken. To select the pad radius, the filling factor of the bearing must be estimated (i.e., the ratio of the effective working area of the thrust pad to the theoretical annular area) and the required total pad area. This can generally be solved by equation (1) or (2): (-D)
For fixed pads: total pad area A=
(D-D2°)
For tilting pads: total pad area A=
In addition, the recommended ratio Dz/D should not exceed the values shown in Figures 3 and 4 for fixed and tilting pad thrust bearings, respectively. If the Dz/D value is large, it is best to increase D. If the Dz/D value is small, the pads are small and numerous, making the bearing design complex and expensive. In this case, a bearing with a smaller number of pads and a larger outer diameter should be used. The outer diameter can be determined by equation (3). {BLB\=A/Z
D,=D,+2B
2.508 1-7/8 5
Ratio D/D,
Number of pads for fixed pad thrust bearing
Ratio Dz/D
Number of pads for tilting pad thrust bearing
4.1.2 Pad width-to-length ratio
JB/T 6520—1992
For the appropriate pad area, it is best to use a nearly square pad, that is, B/L1. Generally, B/L can be selected within the range of 0.8 to 1.2. 4.1.3 Total pad area
The total pad area is determined by the operating requirements or starting requirements of the bearing according to formula (4) or formula (5). For fixed pads: If the pad platform length is 20%L, then [A required for operation = W/P'
A required for starting
For tilting pads:
[A required for operation = W/P'
[A required for starting = W/P
（4）
The total area of the pad should be the larger of the operating requirement and the starting requirement. When the total area of the fixed pad depends on the starting requirement, it is advisable to increase the platform length or use a tilting pad thrust bearing instead. If a high-pressure jacking device is used, the starting requirement can be ignored. 4.1.4 Pad and thrust plate thickness
Generally, the pad thickness H can be selected within the range of (0.35~0.5)L, and the thrust plate thickness H is greater than 0.35L. 4.1.5 Platform length
When machining the fixed pad slope, a platform is often left to support the load during starting. The intersection of the platform and the inclined plane is usually parallel to the starting edge of the pad. The platform length can be (0.1~0.3)L, usually 0.2L. When the total area of the pad depends on the starting requirements, the platform length should be increased to 0.3L.
4.1.6 Pad slope height
Whether the parameter β/hc is selected appropriately has a great impact on the performance of the fixed pad bearing. It is recommended to select a small value (β/h.≤2.0) will lead to high operating temperature and power consumption, and β/h is generally taken. It is more appropriate to be 3.0, that is, the pad slope height β=3hc. When the oil film thickness is very small (such as in small bearings), taking the above value will make the β value very small, resulting in processing difficulties. At this time, the β/h value can be appropriately larger. 4.1.7 Eccentric support parameters of point and line support
For point-supported tilting pad thrust bearings, the radial eccentric support parameter (R, -R)/B is generally selected in the range of (0.515~0.56), and the corresponding radial offset distance e is (0.015~0.06)B, which is biased to the outside of the pad.
Circumferential eccentric support parameter 62/6. Generally, it is selected in the range of 0.55～0.6, and the corresponding circumferential offset distance e=（0.05～0.10）L, which is biased towards the outlet edge of the pad. For the linear support tilting pad thrust bearing: circumferential offset parameter 6z/9. Generally, it is selected in the range of 0.6～0.625, and the corresponding circumferential offset distance e=（0.1～0.125）L, which is biased towards the outlet edge of the pad. Taking the above offset parameters can make the bearing have better bearing capacity, lower friction resistance and temperature rise. 4.1.8 Number of pads
The number of pads Z is generally 6～12. For fixed pads and tilting pad thrust bearings, D/D and B/L can be selected respectively with reference to Figures 3 and 4. The bearing size should be compact to save materials and energy, but the bearing size should meet the requirements of operation and starting as well as the imposed space constraints.
4.1.9 Average pressure ratio of pads
The highest average pressure ratio P of pads can be as high as 7MPa. At this time, careful design and processing are required to maintain appropriate lubricating film thickness between pads and thrust discs and avoid excessive bearing temperature. The average pressure ratio is usually 1.5-2MPa, and 3.5MPa is used in a few cases. The maximum instantaneous pressure ratio is not more than 4MPa. When low-viscosity lubricants are used, the average pressure ratio of pads must be lower than the above value. When the bearing is started, the lubricating film between the pads and the thrust disc has not yet been established. In order to ensure the starting performance, the starting average pressure ratio P is 0.7MPa for fixed pad thrust bearings with bearing alloys and platforms, and 1.5MPa for tilting pad thrust bearings with bearing alloys.
4.1.10 Oil inlet pressure
The lubricating oil pressure P entering the bearing block is 0.05MPa~0.15MPa. 4.1.11 Oil supply temperature
The lubricating oil temperature t supplied to the bearing box is 35℃～45℃. 4.1.12 Oil inlet temperature
The lubricating oil temperature entering the bearing block is strictly ts for direct lubrication and t-tx for oil-free lubrication. 4.1.13 Oil discharge temperature
The lubricating oil temperature t discharged from the bearing box is 50℃～60℃, and the maximum allowable oil discharge temperature Gp) is 70℃. 4.2 Material selection
4.2.1 Thrust plate material
Generally, ordinary carbon steel is used. Chromium alloy steel is easy to "roughen" and is not suitable for use. 4.2.2 Thrust pad material
Generally, a layer of bearing alloy is cast on the surface of the steel pad. When starting with thrust load but without high-pressure jacking, bronze pads are generally not suitable for use due to their poor starting performance.
4.3 Selection of lubricating oil and lubrication method
4.3.1 Lubricating oil
Usually, when selecting lubricating oil, it is necessary to consider the lubrication requirements of the radial bearing or other components at the same time. The specific selection can use the temperature-viscosity characteristic curve of the lubricating oil to select the appropriate lubricating oil. Figure 5 shows the temperature-viscosity characteristic curves of several commonly used lubricating oils. 4.3.2 Lubrication method
Common lubrication methods include oil immersion lubrication and direct lubrication, as shown in Figure 6. In the former, the lubricating oil is mainly supplied from the inner diameter and discharged to the bearing box through the outer diameter and the outlet edge. The lubrication device is relatively simple, and the churning loss is large. It is not suitable for high speed. Direct lubrication is suitable for high speed. It supplies lubricating oil to each pad separately through the oil supply hole. The oil enters the bearing from the inlet edge and is discharged through the inner and outer peripheries and the outlet edge. The lubrication device is more complicated than the former, but it can effectively reduce the churning loss. Direct lubrication should be used as much as possible under possible conditions. 8
Direction of movement,
JB/T 6520—1992
Turbine oil No. 30
Turbine oil No. 20
Temperature ℃
Temperature-viscosity curve of common lubricating oil
Direction of movement
"Supply of lubricating oilLubricating groove
(a) Oil immersion lubrication
Lubrication system diagram
Supply of lubricating oil
(b) Direct lubrication
4.4 Relevant restriction criteria
Low-speed and heavy-load thrust bearings are usually subject to Limited by the minimum oil film thickness, and limited by temperature at medium speed, high speed and heavy load. 4.4.1 Minimum allowable oil film thickness
Lubrication groove
JB/T65201992
In order for the thrust bearing to work safely, a certain minimum oil film thickness must be maintained between the thrust plate and each pad. When the misalignment is very small, the minimum allowable oil film thickness Chm) can be selected according to the B value from Figure 7. When the misalignment is large, it will reduce the oil film thickness of some pads, while others will be The oil film thickness of some tiles increases, so that some tiles are overloaded and overheated. At this time, the misalignment caused by manufacturing, installation or operation must be comprehensively considered. When there is no allowable misalignment, the value can be taken as 1.5×10**d. According to formula (6), Cham] = [hm] + 1.5×10-4d
Because the dirt particles in the lubricating oil can cause surface wear, the mesh size of the filter must be considered when selecting the minimum allowable oil film thickness.
The surface roughness of the pad and thrust plate should be consistent with the minimum oil film thickness. Usually, the surface roughness of the pad and thrust plate of a small bearing is lower than that of similar parts of a large bearing. The surface roughness Ra value should generally not be greater than 1/20 of the difference between the minimum oil film thickness and the allowable value of misalignment. Calculate the
(hm—allowable value of misalignment)
Ra value according to formula (7) - generally (0.8~1.6) μm. If the bearing has frequent starting loads, the surface roughness should be reduced. 14
0. 02 0. 04 0. 06 0. 08 c.10 0. 12 0.14 0. 16Wedge width B, m
Figure? Minimum allowable oil film thickness
4.4.2 Maximum allowable temperature
The yield strength of the tile material depends on the temperature. Under certain working conditions, high tile temperature will cause the material to deform, so it is usually necessary to limit the maximum allowable temperature of the tile. The maximum allowable temperature of the tile depends on the bearing lining material. For bearing alloys, the maximum allowable temperature of the tile (mx] is 120°. If it is necessary to work at high temperatures, aluminum-tin or copper-lead alloy materials can be used. The maximum allowable temperature of aluminum-tin alloy (tin content of about 40%) is 150℃~160℃, and its resistance to bonding and impurity contamination is basically the same as that of bearing alloys. The maximum allowable temperature of copper-lead alloy is 200℃ or higher, but it must be equipped with a high-quality thrust plate (hardness of about 300HV) and a very good lubricating oil filter. Copper can achieve a higher maximum allowable temperature, but it is not suitable due to its poor starting performance. In order to make the bearing work safely, the actual maximum allowable temperature is generally about 20% lower than the above value. Taking bearing alloy as an example, the maximum allowable temperature (alarm temperature) is 90℃～95℃, the shutdown temperature is 100℃～105℃, and the maximum allowable temperature is 100℃～105℃.9 Average pressure ratio of pads
The highest average pressure ratio of pads P can be as high as 7MPa. At this time, careful design and processing are required to maintain appropriate lubricating film thickness between pads and thrust discs and avoid excessive bearing temperature. The average pressure ratio is usually 1.5-2MPa, and 3.5MPa is used in a few cases. The maximum instantaneous pressure ratio is not more than 4MPa. When low-viscosity lubricants are used, the average pressure ratio of pads must be lower than the above value. When the bearing is started, the lubricating film between the pads and the thrust disc has not yet been established. In order to ensure the starting performance, the starting average pressure ratio P is 0.7MPa for fixed pad thrust bearings with bearing alloys and platforms, and 1.5MPa for tilting pad thrust bearings with bearing alloys.
4.1.10 Oil inlet pressure
The lubricating oil pressure P entering the bearing block is 0.05MPa~0.15MPa. 4.1.11 Oil supply temperature
The lubricating oil temperature t supplied to the bearing box is 35℃～45℃. 4.1.12 Oil inlet temperature
The lubricating oil temperature entering the bearing block is strictly ts for direct lubrication and t-tx for oil-free lubrication. 4.1.13 Oil discharge temperature
The lubricating oil temperature t discharged from the bearing box is 50℃～60℃, and the maximum allowable oil discharge temperature Gp) is 70℃. 4.2 Material selection
4.2.1 Thrust plate material
Generally, ordinary carbon steel is used. Chromium alloy steel is easy to "roughen" and is not suitable for use. 4.2.2 Thrust pad material
Generally, a layer of bearing alloy is cast on the surface of the steel pad. When starting with thrust load but without high-pressure jacking, bronze pads are generally not suitable for use due to their poor starting performance.
4.3 Selection of lubricating oil and lubrication method
4.3.1 Lubricating oil
Usually, when selecting lubricating oil, it is necessary to consider the lubrication requirements of the radial bearing or other components at the same time. The specific selection can use the temperature-viscosity characteristic curve of the lubricating oil to select the appropriate lubricating oil. Figure 5 shows the temperature-viscosity characteristic curves of several commonly used lubricating oils. 4.3.2 Lubrication method
Common lubrication methods include oil immersion lubrication and direct lubrication, as shown in Figure 6. In the former, the lubricating oil is mainly supplied from the inner diameter and discharged to the bearing box through the outer diameter and the outlet edge. The lubrication device is relatively simple, and the churning loss is large. It is not suitable for high speed. Direct lubrication is suitable for high speed. It supplies lubricating oil to each pad separately through the oil supply hole. The oil enters the bearing from the inlet edge and is discharged through the inner and outer peripheries and the outlet edge. The lubrication device is more complicated than the former, but it can effectively reduce the churning loss. Direct lubrication should be used as much as possible under possible conditions. 8
Direction of movement,
JB/T 6520—1992
Turbine oil No. 30
Turbine oil No. 20
Temperature ℃
Temperature-viscosity curve of common lubricating oil
Direction of movement
"Supply of lubricating oilLubricating groove
(a) Oil immersion lubrication
Lubrication system diagram
Supply of lubricating oil
(b) Direct lubrication
4.4 Relevant restriction criteria
Low-speed and heavy-load thrust bearings are usually subject to Limited by the minimum oil film thickness, and limited by temperature at medium speed, high speed and heavy load. 4.4.1 Minimum allowable oil film thickness
Lubrication groove
JB/T65201992
In order for the thrust bearing to work safely, a certain minimum oil film thickness must be maintained between the thrust plate and each pad. When the misalignment is very small, the minimum allowable oil film thickness Chm) can be selected according to the B value from Figure 7. When the misalignment is large, it will reduce the oil film thickness of some pads, while others will be The oil film thickness of some tiles increases, so that some tiles are overloaded and overheated. At this time, the misalignment caused by manufacturing, installation or operation must be comprehensively considered. When there is no allowable misalignment, the value can be taken as 1.5×10**d. According to formula (6), Cham] = [hm] + 1.5×10-4d
Because the dirt particles in the lubricating oil can cause surface wear, the mesh size of the filter must be considered when selecting the minimum allowable oil film thickness.
The surface roughness of the pad and thrust plate should be consistent with the minimum oil film thickness. Usually, the surface roughness of the pad and thrust plate of a small bearing is lower than that of similar parts of a large bearing. The surface roughness Ra value should generally not be greater than 1/20 of the difference between the minimum oil film thickness and the allowable value of misalignment. Calculate the
(hm—allowable value of misalignment)
Ra value according to formula (7) - generally (0.8~1.6) μm. If the bearing has frequent starting loads, the surface roughness should be reduced. 14
0. 02 0. 04 0. 06 0. 08 c.10 0. 12 0.14 0. 16Wedge width B, m
Figure? Minimum allowable oil film thickness
4.4.2 Maximum allowable temperature
The yield strength of the tile material depends on the temperature. Under certain working conditions, high tile temperature will cause the material to deform, so it is usually necessary to limit the maximum allowable temperature of the tile. The maximum allowable temperature of the tile depends on the bearing lining material. For bearing alloys, the maximum allowable temperature of the tile (mx] is 120°. If it is necessary to work at high temperatures, aluminum-tin or copper-lead alloy materials can be used. The maximum allowable temperature of aluminum-tin alloy (tin content of about 40%) is 150℃~160℃, and its resistance to bonding and impurity contamination is basically the same as that of bearing alloys. The maximum allowable temperature of copper-lead alloy is 200℃ or higher, but it must be equipped with a high-quality thrust plate (hardness of about 300HV) and a very good lubricating oil filter. Copper can achieve a higher maximum allowable temperature, but it is not suitable due to its poor starting performance. In order to make the bearing work safely, the actual maximum allowable temperature is generally about 20% lower than the above value. Taking bearing alloy as an example, the maximum allowable temperature (alarm temperature) is 90℃～95℃, the shutdown temperature is 100℃～105℃, and the maximum allowable temperature is 100℃～105℃.9 Average pressure ratio of pads
The highest average pressure ratio of pads P can be as high as 7MPa. At this time, careful design and processing are required to maintain appropriate lubricating film thickness between pads and thrust discs and avoid excessive bearing temperature. The average pressure ratio is usually 1.5-2MPa, and 3.5MPa is used in a few cases. The maximum instantaneous pressure ratio is not more than 4MPa. When low-viscosity lubricants are used, the average pressure ratio of pads must be lower than the above value. When the bearing is started, the lubricating film between the pads and the thrust disc has not yet been established. In order to ensure the starting performance, the starting average pressure ratio P is 0.7MPa for fixed pad thrust bearings with bearing alloys and 7
JB/T 6520—1992
platforms, and the starting average pressure ratio of tilting pad thrust bearings with bearing alloys is 1.5MPa.
4.1.10 Oil inlet pressure
The lubricating oil pressure P entering the bearing block is 0.05MPa~0.15MPa. 4.1.11 Oil supply temperature
The lubricating oil temperature t supplied to the bearing box is 35℃～45℃. 4.1.12 Oil inlet temperature
The lubricating oil temperature entering the bearing block is strictly ts for direct lubrication and t-tx for oil-free lubrication. 4.1.13 Oil discharge temperature
The lubricating oil temperature t discharged from the bearing box is 50℃～60℃, and the maximum allowable oil discharge temperature Gp) is 70℃. 4.2 Material selection
4.2.1 Thrust plate material
Generally, ordinary carbon steel is used. Chromium alloy steel is easy to "roughen" and is not suitable for use. 4.2.2 Thrust pad material
Generally, a layer of bearing alloy is cast on the surface of the steel pad. When starting with thrust load but without high-pressure jacking, bronze pads are generally not suitable for use due to their poor starting performance.
4.3 Selection of lubricating oil and lubrication method
4.3.1 Lubricating oil
Usually, when selecting lubricating oil, it is necessary to consider the lubrication requirements of the radial bearing or other components at the same time. The specific selection can use the temperature-viscosity characteristic curve of the lubricating oil to select the appropriate lubricating oil. Figure 5 shows the temperature-viscosity characteristic curves of several commonly used lubricating oils. 4.3.2 Lubrication method
Common lubrication methods include oil immersion lubrication and direct lubrication, as shown in Figure 6. In the former, the lubricating oil is mainly supplied from the inner diameter and discharged to the bearing box through the outer diameter and the outlet edge. The lubrication device is relatively simple, and the churning loss is large. It is not suitable for high speed. Direct lubrication is suitable for high speed. It supplies lubricating oil to each pad separately through the oil supply hole. The oil enters the bearing from the inlet edge and is discharged through the inner and outer peripheries and the outlet edge. The lubrication device is more complicated than the former, but it can effectively reduce the churning loss. Direct lubrication should be used as much as possible under possible conditions. 8
Direction of movement,
JB/T 6520—1992
Turbine oil No. 30
Turbine oil No. 20
Temperature ℃
Temperature-viscosity curve of common lubricating oil
Direction of movement
"Supply of lubricating oilLubricating groove
(a) Oil immersion lubrication
Lubrication system diagram
Supply of lubricating oil
(b) Direct lubrication
4.4 Relevant restriction criteria
Low-speed and heavy-load thrust bearings are usually subject to Limited by the minimum oil film thickness, and limited by temperature at medium speed, high speed and heavy load. 4.4.1 Minimum allowable oil film thickness
Lubrication groove
JB/T65201992
In order for the thrust bearing to work safely, a certain minimum oil film thickness must be maintained between the thrust plate and each pad. When the misalignment is very small, the minimum allowable oil film thickness Chm) can be selected according to the B value from Figure 7. When the misalignment is large, it will reduce the oil film thickness of some pads, while others will be The oil film thickness of some tiles increases, so that some tiles are overloaded and overheated. At this time, the misalignment caused by manufacturing, installation or operation must be comprehensively considered. When there is no allowable misalignment, the value can be taken as 1.5×10**d. According to formula (6), Cham] = [hm] + 1.5×10-4d
Because the dirt particles in the lubricating oil can cause surface wear, the mesh size of the filter must be considered when selecting the minimum allowable oil film thickness.
The surface roughness of the pad and thrust plate should be consistent with the minimum oil film thickness. Usually, the surface roughness of the pad and thrust plate of a small bearing is lower than that of similar parts of a large bearing. The surface roughness Ra value should generally not be greater than 1/20 of the difference between the minimum oil film thickness and the allowable value of misalignment. Calculate the
(hm—allowable value of misalignment)
Ra value according to formula (7) - generally (0.8~1.6) μm. If the bearing has frequent starting loads, the surface roughness should be reduced. 14
0. 02 0. 04 0. 06 0. 08 c.10 0. 12 0.14 0. 16Wedge width B, m
Figure? Minimum allowable oil film thickness
4.4.2 Maximum allowable temperature
The yield strength of the tile material depends on the temperature. Under certain working conditions, high tile temperature will cause the material to deform, so it is usually necessary to limit the maximum allowable temperature of the tile. The maximum allowable temperature of the tile depends on the bearing lining material. For bearing alloys, the maximum allowable temperature of the tile (mx] is 120°. If it is necessary to work at high temperatures, aluminum-tin or copper-lead alloy materials can be used. The maximum allowable temperature of aluminum-tin alloy (tin content of about 40%) is 150℃~160℃, and its resistance to bonding and impurity contamination is basically the same as that of bearing alloys. The maximum allowable temperature of copper-lead alloy is 200℃ or higher, but it must be equipped with a high-quality thrust plate (hardness of about 300HV) and a very good lubricating oil filter. Copper can achieve a higher maximum allowable temperature, but it is not suitable due to its poor starting performance. In order to make the bearing work safely, the actual maximum allowable temperature is generally about 20% lower than the above value. Taking bearing alloy as an example, the maximum allowable temperature (alarm temperature) is 90℃～95℃, the shutdown temperature is 100℃～105℃, and the maximum allowable temperature is 100℃～105℃.2 Lubrication method
Common lubrication methods include oil immersion lubrication and direct lubrication (see Figure 6). In the former, the lubricating oil is mainly supplied from the inner diameter and discharged to the bearing box through the outer diameter and the outlet. The lubrication device is relatively simple, and the churning loss is large. It is not suitable for high speed. Direct lubrication is suitable for high speed. It supplies lubricating oil to each tile through the oil supply hole. The oil enters the bearing from the inlet side and is discharged through the inner and outer peripheries and the outlet side. The lubrication device is more complicated than the former, but it can effectively reduce the churning loss. Direct lubrication should be used as much as possible under possible conditions. 8
Movement direction,
JB/T 6520—1992
Turbine oil No. 30
Turbine oil No. 20
Temperature ℃
Temperature-viscosity curve of common lubricating oil
Direction of movement
"Supply of lubricating oilLubricating groove
(a) Oil immersion lubrication
Lubrication system diagram
Supply of lubricating oil
(b) Direct lubrication
4.4 Relevant restriction criteria
Low-speed and heavy-load thrust bearings are usually subject to Limited by the minimum oil film thickness, and limited by temperature at medium speed, high speed and heavy load. 4.4.1 Minimum allowable oil film thickness
Lubrication groove
JB/T65201992
In order for the thrust bearing to work safely, a certain minimum oil film thickness must be maintained between the thrust plate and each pad. When the misalignment is very small, the minimum allowable oil film thickness Chm) can be selected according to the B value from Figure 7. When the misalignment is large, it will reduce the oil film thickness of some pads, while others will be The oil film thickness of some tiles increases, so that some tiles are overloaded and overheated. At this time, the misalignment caused by manufacturing, installation or operation must be comprehensively considered. When there is no allowable misalignment, the value can be taken as 1.5×10**d. According to formula (6), Cham] = [hm] + 1.5×10-4d
Because the dirt particles in the lubricating oil can cause surface wear, the mesh size of the filter must be considered when selecting the minimum allowable oil film thickness.
The surface roughness of the pad and thrust plate should be consistent with the minimum oil film thickness. Usually, the surface roughness of the pad and thrust plate of a small bearing is lower than that of similar parts of a large bearing. The surface roughness Ra value should generally not be greater than 1/20 of the difference between the minimum oil film thickness and the allowable value of misalignment. Calculate the
(hm—allowable value of misalignment)
Ra value according to formula (7) - generally (0.8~1.6) μm. If the bearing has frequent starting loads, the surface roughness should be reduced. 14
0. 02 0. 04 0. 06 0. 08 c.10 0. 12 0.14 0. 16Wedge width B, m
Figure? Minimum allowable oil film thickness
4.4.2 Maximum allowable temperature
The yield strength of the tile material depends on the temperature. Under certain working conditions, high tile temperature will cause the material to deform, so it is usually necessary to limit the maximum allowable temperature of the tile. The maximum allowable temperature of the tile depends on the bearing lining material. For bearing alloys, the maximum allowable temperature of the tile (mx] is 120°. If it is necessary to work at high temperatures, aluminum-tin or copper-lead alloy materials can be used. The maximum allowable temperature of aluminum-tin alloy (tin content of about 40%) is 150℃~160℃, and its resistance to bonding and impurity contamination is basically the same as that of bearing alloys. The maximum allowable temperature of copper-lead alloy is 200℃ or higher, but it must be equipped with a high-quality thrust plate (hardness of about 300HV) and a very good lubricating oil filter. Copper can achieve a higher maximum allowable temperature, but it is not suitable due to its poor starting performance. In order to make the bearing work safely, the actual maximum allowable temperature is generally about 20% lower than the above value. Taking bearing alloy as an example, the maximum allowable temperature (alarm temperature) is 90℃～95℃, the shutdown temperature is 100℃～105℃, and the maximum allowable temperature is 100℃～105℃.2 Lubrication method
Common lubrication methods include oil immersion lubrication and direct lubrication (see Figure 6). In the former, the lubricating oil is mainly supplied from the inner diameter and discharged to the bearing box through the outer diameter and the outlet. The lubrication device is relatively simple, and the churning loss is large. It is not suitable for high speed. Direct lubrication is suitable for high speed. It supplies lubricating oil to each tile through the oil supply hole. The oil enters the bearing from the inlet side and is discharged through the inner and outer peripheries and the outlet side. The lubrication device is more complicated than the former, but it can effectively reduce the churning loss. Direct lubrication should be used as much as possible under possible conditions. 8
Movement direction,
JB/T 6520—1992
Turbine oil No. 30
Turbine oil No. 20
Temperature ℃
Temperature-viscosity curve of common lubricating oil
Direction of movement
"Supply of lubricating oilLubricating groove
(a) Oil immersion lubrication
Lubrication system diagram
Supply of lubricating oil
(b) Direct lubrication
4.4 Relevant restriction criteria
Low-speed and heavy-load thrust bearings are usually subject to Limited by the minimum oil film thickness, and limited by temperature at medium speed, high speed and heavy load. 4.4.1 Minimum allowable oil film thickness
Lubrication groove
JB/T65201992
In order for the thrust bearing to work safely, a certain minimum oil film thickness must be maintained between the thrust plate and each pad. When the misalignment is very small, the minimum allowable oil film thickness Chm) can be selected according to the B value from Figure 7. When the misalignment is large, it will reduce the oil film thickness of some pads, while others will be The oil film thickness of some tiles increases, so that some tiles are overloaded and overheated. At this time, the misalignment caused by manufacturing, installation or operation must be comprehensively considered. When there is no allowable misalignment, the value can be taken as 1.5×10**d. According to formula (6), Cham] = [hm] + 1.5×10-4d
Because the dirt particles in the lubricating oil can cause surface wear, the mesh size of the filter must be considered when selecting the minimum allowable oil film thickness.
The surface roughness of the pad and thrust plate should be consistent with the minimum oil film thickness. Usually, the surface roughness of the pad and thrust plate of a small bearing is lower than that of similar parts of a large bearing. The surface roughness Ra value should generally not be greater than 1/20 of the difference between the minimum oil film thickness and the allowable value of misalignment. Calculate the
(hm—allowable value of misalignment)
Ra value according to formula (7) - generally (0.8~1.6) μm. If the bearing has frequent starting loads, the surface roughness should be reduced. 14
0. 02 0. 04 0. 06 0. 08 c.10 0. 12 0.14 0. 16Wedge width B, m
Figure? Minimum allowable oil film thickness
4.4.2 Maximum allowable temperature
The yield strength of the tile material depends on the temperature. Under certain working conditions, high tile temperature will cause the material to deform, so it is usually necessary to limit the maximum allowable temperature of the tile. The maximum allowable temperature of the tile depends on the bearing lining material. For bearing alloys, the maximum allowable temperature of the tile (mx] is 120°. If it is necessary to work at high temperatures, aluminum-tin or copper-lead alloy materials can be used. The maximum allowable temperature of aluminum-tin alloy (tin content of about 40%) is 150℃~160℃, and its resistance to bonding and impurity contamination is basically the same as that of bearing alloys. The maximum allowable temperature of copper-lead alloy is 200℃ or higher, but it must be equipped with a high-quality thrust plate (hardness of about 300HV) and a very good lubricating oil filter. Copper can achieve a higher maximum allowable temperature, but it is not suitable due to its poor starting performance. In order to make the bearing work safely, the actual maximum allowable temperature is generally about 20% lower than the above value. Taking bearing alloy as an example, the maximum allowable temperature (alarm temperature) is 90℃～95℃, the shutdown temperature is 100℃～105℃, and the maximum allowable temperature is 100℃～105℃.
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