JB/T 5391-1991 Regulations for magnetic particle inspection of rolling bearing parts of railway rolling stock
Some standard content:
Machinery Industry Standards of the People's Republic of China
Rolling Bearing Parts for Railway Locomotives
Magnetic Particle Flaw Detection Procedures
Subject Content and Scope of Application
JB/T 5391--91||tt| |This standard specifies the magnetic particle flaw detection methods, magnetization specifications, flaw detection procedures and acceptance rules for rolling bearings used in railway locomotives and rolling stock (hereinafter referred to as "railway bearings").
This standard is applicable to magnetic particle inspection for surface and near-surface cracks and other defects on railway bearing parts made of ferromagnetic materials. Other civilian bearing parts can also be implemented as a reference. 2 Reference standards
GB9445 Technical qualification rules for non-destructive testing personnel GE3721
Magnetic particle flaw detector
GB2536 Transformer oil
GB253 Kerosene for lamps
JB3111 No camera Testing terminology
HB/Z72 Aviation Parts Magnetic Particle Inspection Manual 3-General Provisions
3.1 According to the technical requirements of rolling bearings for railway locomotives and passenger and truck vehicles, railway bearing parts (rings and rollers) All should be subject to 100% magnetic particle inspection. The parts after flaw detection shall comply with the requirements of the acceptance rules of this regulation. 3.2 All railway bearing parts are subjected to magnetic particle testing using wet methods. 3.3 Depending on the specific conditions of the parts being inspected, the continuous method or the residual magnetization method can be used for magnetic particle inspection. The continuous method is chosen first. 3.4 Depending on the specific conditions of the parts being inspected, the fluorescent magnetic particle method or the non-fluorescent magnetic particle method can be used for magnetic particle flaw detection. The fluorescent magnetic particle method is selected first.
3.5 Magnetic particle inspection should be carried out on finished parts after processing processes that are prone to defects (such as heat treatment, grinding, cold and hot deformation processing, etc.), but for bearing rings that require surface phosphating treatment, Carry out flaw detection inspection before phosphating treatment. 4 Flaw detection personnel
4.1 All operators engaged in magnetic particle flaw detection must undergo professional technical training and obtain the technical qualification certificate for non-destructive testing personnel of level 1 or level I or above specified in GB9445 before they can perform magnetic particle flaw detection operations . 4.2 Magnetic particle inspection personnel should have good vision, and the corrected or uncorrected vision should be above 5.0 (checked according to the standard logarithmic eye chart). The near vision should be checked according to the Jaeger No. 1 visual acuity chart. The near vision should be above 1.0. Patients with color blindness are not allowed to engage in magnetic particle inspection work.
The Ministry of Mechanical and Electronic Industry of the People's Republic of China approved the implementation on 1992-07-01 on 1991-06-25
347
5 flaw detection equipment
JB/T 5391--91
5.1 All magnetic particle flaw detection machines and their devices should comply with the regulations of GB3721. Magnetic particle inspection of bearing parts generally uses an AC magnetic particle inspection machine.
5.2 When using the residual magnet method for magnetic particle flaw detection, the AC magnetic particle flaw detector should be equipped with a power-off phase controller to ensure that the magnetized shield of the part has sufficient and stable residual magnetism. Otherwise, the AC magnetic particle flaw detector shall not use the residual magnet method to inspect railway bearings. 5.3 The magnetic particle flaw detector should be installed in a place away from heat and fire sources, with a dedicated power supply and good ventilation. 5.4 The demagnetizer or magnetic device used for bearing parts is allowed to be installed separately. The installation direction should be such that the direction of the magnetic field generated by the demagnetizer is perpendicular to the ground. magnetic field. 5.5 When using fluorescent magnetic particle inspection, the flaw detector should be equipped with an ultraviolet lamp (black light lamp) with a wavelength of 320~~400nm. The ultraviolet irradiance at a distance of 400mm from the lamp shall not be less than 800~~1000μW/cm2. The inspection area should be blackened and the surrounding areas The white light illumination shall not exceed 101x. When using non-fluorescent magnetic powder for inspection, the white light illumination in the inspection area shall not be less than 5001x. 6 Magnetic Powder
6.1 Non-fluorescent magnetic powder is generally black Fe.O and reddish-brown -Fe2; , and other colors of magnetic powder. Fluorescent magnetic powder is based on magnetic iron oxide powder, industrial pure iron powder or carbon-based iron powder as the core, and is surrounded by fluorescent dye particles. Fluorescent magnetic powder should have high brightness under ultraviolet irradiation, preferably yellow-green
6.2 magnetic powder should have high magnetic permeability, low coercive force and low residual magnetism. The mass of non-fluorescent magnetic powder weighed by the magnetic weighing method shall not be less than 7g, and the mass of fluorescent magnetic powder shall not be less than 6g
6.3 The magnetic powder should have good suspension and dispersion in the dispersant. Magnetic powder should be able to pass through a sieve opening smaller than 63um. When using the alcohol precipitation method to test the particle size of magnetic powder, the height of the magnetic powder liquid column shall not be less than 180mm. 7. Magnetic suspension
7.1 The concentration of magnetic suspension is expressed by the number of grams of magnetic powder contained in each liter of liquid. The concentration of magnetic suspension is specified as follows: non-fluorescent magnetic powder
fluorescent magnetic powder
7.2 oil magnetic suspension
15~~30g/1
1~5 g/L| |tt||7.2.1 During non-fluorescent magnetic particle inspection of bearing parts, it is stipulated to use a mixture of transformer oil and kerosene as the dispersant (carrier fluid). The ratio of transformer oil to kerosene should be 1:11:3. Transformer oil and kerosene Comply with the technical requirements of GB2536 and GB253 respectively. 7.2.2 When fluorescent magnetic particle inspection is used for bearing parts, odorless kerosene that is basically non-fluorescent should be used as the dispersant. 7.2.3 When preparing the oil magnetic suspension, a small amount of weighed oil should be taken out and mixed evenly with the magnetic powder to completely wet the magnetic powder and stir into a paste. Then, add the rest of the oil while stirring until thoroughly mixed. 7.3 Water magnetic suspension
7.3.1 The water dispersant after adding various treatment agents should have good wetting, rust prevention, defoaming, dispersion and stability, and should be basically free of Fluorescence, its pH value shall not be greater than 10.5. 7.3.2 During non-fluorescent magnetic particle inspection, the following formula can be used to prepare aqueous magnetic fluid: No. 100 concentrated emulsion
triethanolamine
sodium nitrite|| tt||Defoaming agent
Magnetic powder
Water
10 g
5g
5g
0.5～1g
15~30g
11
When preparing, first add concentrated milk to 1L 50℃ warm water, stir until completely dissolved, then add sodium nitrite, triethanolamine and defoaming agent, add Stir thoroughly after each ingredient. When adding magnetic powder, first take a small amount of dispersant and mix it with the magnetic powder to completely wet the magnetic powder, and then add the rest of the dispersant.
7.3.3 If domestic YC-2 type fluorescent magnetic particle is used for flaw detection, YF type magnetic particle dispersant can be used, or the following formula can be used to prepare aqueous magnetic suspension:
Emulsifier (JFC)| |tt||Sodium nitrite
No. 28 defoaming agent
Magnetic powder
Water
5g
15 g
0. 5 ~1g
1~sg
11.
When preparing, stir the emulsifier and defoamer evenly, and add enough water in proportion to become a water dispersant. Use a small amount of water dispersant and magnetic powder to mix, then add the remaining amount of water dispersant, and finally add sodium nitrite. 7.4 Magnetic suspension prepared with other formulas
It is allowed to prepare magnetic suspension with other formulas, but its performance should meet the requirements, and test pieces (blocks) with natural defects or artificial defects should be used for flaw detection, and the defective magnetic marks should be displayed Clear before use. 8 Flaw detection operating procedures
8.1 Operating procedures
8.1.1 The main operating procedures during continuous flaw detection are as follows: a. Cleaning. Clean the surface of parts and other surfaces; b. Magnetize. The parts should be evenly wetted with the magnetic suspension, then powered on for 1 to 3 seconds, and at the same time, the magnetic suspension should be poured. After stopping pouring, power on several times, 0.5 to 1 each time. It should be noted that the city-shaped magnetic traces at the end of magnetization cannot be washed away by the flowing magnetic suspension; c. Observe and inspect. Observation and inspection can be carried out during magnetization or after magnetization; d, demagnetization;
e, cleaning and rust prevention of parts:
f. Recording of flaw detection results.
8.1.2 The operating procedure of the residual magnetization method is roughly the same as that of the continuous method. The difference is: a. Magnetization. When dancing, power is on, and the AC electromagnetic magnetization time is 0.5~~1S. The impact current magnetization time is 0.015; b. Apply magnetic suspension. Only after magnetization can the magnetic suspension be poured onto the parts. Generally, the parts are poured 2 to 3 times, or the parts are immersed in the evenly stirred magnetic suspension for about 10 to 30 5 seconds, and then slowly taken out and left to stand for 1 to 9 minutes, and finally observed and inspected. . 8.2 Precautions during operation
8.2.1 When the parts are clamped between the magnetized heads of the flaw detector, the clamping force must be appropriate and the parts must not be deformed. 8.2.2 When using the direct current method to magnetize parts, the contact should be good and the magnetizing current should not be too large. It is best to use the continuous method to avoid burning the parts. 8.2.3 When using the residual magnetism method for flaw detection, from the time of magnetization to the end of magnetic mark observation, the parts must not collide with, rub against or come into contact with other ferromagnetic objects to avoid the occurrence of irrelevant magnetic marks. 9Magnetization technology
9.1. Magnetization direction
When the defect direction is perpendicular to the magnetic flux direction, the defect display sensitivity is the highest. When the defect direction is parallel to the magnetic flux direction, the defect may not be displayed. Therefore, it is necessary to check for defects in all directions to avoid missed inspections. Bearing parts must be magnetized in at least two directions, circumferential and longitudinal, or multi-directional magnetization (composite magnetization). 9.2 Magnetization method
9.2.1 Threading method
A method in which the magnetizing current passes through a conductor (mandrel) that penetrates into the hole of the part to generate a circumferential magnetic field in the part. This method can find axial defects on the inner and outer surfaces of the bearing ring and radial defects on both end surfaces. 349
JB/T 5391—91
9.2.1.1 Generally, a special fixture should be designed so that the conductor is located at the center of the part to obtain a concentric magnetic field with respect to the centerline of the part as the axis. .
9.2.1.2 When the diameter of the part is large and the magnetizing current of the flaw detector is insufficient, the conductor is allowed to be biased (offset mandrel method). During bias magnetization, the effective magnetization distance along the circumference is approximately 4 times the diameter of the conductor. Therefore, the parts must be rotated multiple times during inspection to ensure 10% reselection in adjacent inspection areas. When using the continuous method, the parts must be rotated each time After that, all need to be inspected. 9.2.1.3 When magnetizing through the rod method, multiple parts are allowed to be magnetized on the conductor at the same time, but it should be noted that appropriate intervals should be left between the parts. The parts located at both ends of the conductor should be at least 15mm away from the chuck of the flaw detector. . 9.2.2 Direct energization method
The magnetizing current passes directly through the part itself to generate a circumferential magnetic field inside or around the part. This method can find defects parallel to the direction of current flow, such as roller material cracks, axial rate fire cracks, etc. 9.2.2.1 When using the direct energization method, the current can pass along the axis of the part (axial energization method) or in the direction perpendicular to the axis of the part (right-angle energization method).
9.2.2.2 When directly energized, a clamp made of non-magnetic material is allowed to connect multiple rollers in series and magnetize them simultaneously. 9.2.3 Coil method
This method is to place the part in a solenoid coil carrying current and generate a longitudinal magnetic field in the part. This method can find defects perpendicular to the axis of the coil.
9.2.3.1 When the coil is magnetized, the degree of magnetization is related to the L/D value of the part (L is the length of the part, D is the diameter of the part). The larger the L/D, the easier it is to magnetize. Therefore, when magnetizing rollers, multiple rollers should be connected in series for magnetization. The I./D value after series connection should be greater than 5. 9.2.3.2 When the coil is magnetized, since the magnetic lines of force at both ends of the part are divergent, the magnetic field lines at both ends of the part are divergent. The flaw detection sensitivity of the terminal is reduced and the magnetic marks are blurred. The quick power-off method should be used to eliminate
9.2.3.3 When the inner diameter of the coil greatly exceeds the diameter of the part, the part should be magnetized close to the coil wall. Generally, the part axis should be parallel to the coil axis.
9.2.4 Magnetic Yoke Method
This method can generate a longitudinal magnetic field in the part by placing the part between the electromagnetic yoke or the permanent magnetic yoke. This method shows defects that are perpendicular to the magnetic field lines.
9.2.4.1 Under normal circumstances, AC yoke magnetization should be used for flaw detection of bearing parts. DC yoke or permanent yoke magnetization should not be used. 9.2.4.2 When using the yoke method to magnetize the ferrule, if the end face of the ferrule is larger than the magnet The yoke end face should be magnetized segmentally along the ferrule end face, and the effective magnetization area should overlap by 10% each time.
9.2.4.3 When using the yoke method to magnetize rollers, the area of ??the fixture for mounting the rollers shall not be larger than the area of ??the yoke. 9.2.4.4 When using the yoke method to magnetize parts, high-density leakage magnetic flux will be generated locally at and near the contact area between the yoke and the part, and incoherent magnetic traces will appear, which should be eliminated by changing the direction of the magnetic poles. 9.2.5 Induced current method
This is a magnetization method that uses the part as the secondary coil of the transformer and causes the alternating magnetic flux to induce a circumferential current on the part. The magnetic field generated by the induced current is annular, and the ferrule can be found Circumferential defects on inner and outer walls and end faces. 9.2.5.1 When using the induced current method, except for the parts to be inspected, there must be no other conductors surrounding the magnetic field. 9.2.5.2 The induced current method generally uses alternating current, or current with a quick power-off device can also be used. When the power is cut off quickly, an inrush current with a very strong current value can be induced in the parts, and then the residual magnetism method is used to check. 9.2.6 Composite magnetization method
Apply two or more magnetic fields in different directions on the part at the same time. The direction of the synthetic magnetic field on the part continuously changes (forming a swing magnetic field or a rotating magnetic field). One magnetization is enough. Detect defects in multiple directions on the part. 9.2.6.1 There are many forms of composite magnetization. The following three types are commonly used for flaw detection of bearing parts: a. Induced current combined with a phase-shifted AC excitation current; b. Cross coil:
350||tt| |C. Circumferential magnetization by rod-through method and longitudinal magnetization of the yoke. JB/T 5391--91
9.2.6.2 The composite magnetization method can only be used for the continuous method and cannot be used for the residual magnetization method. 10 Magnetization specifications
10.1 Circumferential magnetization specifications
General rules for selection of circumferential magnetization specifications
10. t. 1
10.1.1.1 Cylindrical or round simple parts During circumferential magnetization, calculate the magnetizing current value according to formula (1): HD
320
Wuzhong: 1
magnetizing current intensity, A;
H-- Magnetic field strength, A/m;
1)
D-part diameter, mm.
10.1.1.2 The standard specification for circumferential magnetization stipulates that the magnetic field intensity on the surface of the part should reach 2400A/m (30Oe) when using the continuous method, and 8000A/m (100Oe) when using the residual magnetization method; for high stress, Parts working under high load conditions should adopt strict specifications. The surface magnetic field strength of the parts should reach 4800A/m (600e) when using the continuous method and 14400A/m (180Qe) when using the residual magnetization method. Relaxed specifications should be used for rough machining of rough parts. , when using the residual magnet method, the magnetic field intensity on the surface of the part should reach 6366A/m (80Oe). Those who have the conditions should measure and draw the magnetization curve according to the material and heat treatment status of the parts, and formulate magnetization specifications 10.1.2 Magnetization specifications for direct energization method and center penetration method 10.1.2.1 For locomotive axle parts and passengers working under high load conditions , the bearing parts of the vehicle axle of the truck adopt the following magnetizing current value:
Continuous method: 1 (15~18)D
Residual magnet method: 1 (30~~40)D|| tt||In the formula: I magnetizing current intensity, A (AC effective value); D-part diameter, mm (calculated as the outer diameter of the ferrule) 10.1.2.2 For bearing parts working in other parts, the following magnetizing current values ??are used: Continuous Method: 1=(10～15)D
Residual magnetization method: I(25～40)D
10.1.3 Offset mandrel method magnetization specifications
When using the continuous method , the magnetizing current value can be selected according to the table. The wall thickness of the part is mm
2~5
5~8
811
11~14
Note: For quarter parts with a wall thickness greater than 14mm, the magnetizing current increases by 250A for every 3mm increase in wall thickness. 10.2 Longitudinal magnetization specifications
Magnetizing current A
1000
1250
1500
1750
10.2.1 When the coil is magnetized, the patient should be considered Influence of the demagnetization factor of parts, the residual magnetization method selects the magnetic field intensity value according to the following principles: a.
h,
c
L/D≥10 parts, no-load coil The center magnetic field strength should be greater than 12000A/m (1500e); 23. When magnetizing through the rod method, multiple parts are allowed to be magnetized on the conductor at the same time, but it should be noted that there should be an appropriate distance between the parts. The parts at both ends of the conductor should be at least 15mm away from the chuck of the flaw detector. 9.2.2 Direct energization method
The magnetizing current passes directly through the part itself to generate a circumferential magnetic field inside or around the part. This method can find defects parallel to the direction of current flow, such as roller material cracks, axial rate fire cracks, etc. 9.2.2.1 When using the direct energization method, the current can pass along the axis of the part (axial energization method) or in the direction perpendicular to the axis of the part (right-angle energization method).
9.2.2.2 When directly energized, a fixture made of non-magnetic material is allowed to connect multiple rollers in series and magnetize them simultaneously. 9.2.3 Coil method
This method is to place the part in a solenoid coil carrying current and generate a longitudinal magnetic field in the part. This method can find defects perpendicular to the axis of the coil.
9.2.3.1 When the coil is magnetized, the degree of magnetization is related to the L/D value of the part (L is the length of the part, D is the diameter of the part). The larger the L/D, the easier it is to magnetize. Therefore, when magnetizing rollers, multiple rollers should be connected in series for magnetization. The I./D value after series connection should be greater than 5. 9.2.3.2 When the coil is magnetized, since the magnetic lines of force at both ends of the part are divergent, the magnetic field lines at both ends of the part are divergent. The flaw detection sensitivity of the end is reduced and the magnetic marks are blurred. The quick power-off method should be used to eliminate
9.2.3.3 When the inner diameter of the coil greatly exceeds the diameter of the part, the part should be magnetized close to the coil wall. Generally, the part axis should be parallel to the coil axis.
9.2.4 Magnetic Yoke Method
This method can generate a longitudinal magnetic field in the part by placing the part between the electromagnetic yoke or the permanent magnetic yoke. This method shows defects that are perpendicular to the magnetic field lines.
9.2.4.1 Under normal circumstances, AC yoke magnetization should be used for flaw detection of bearing parts. DC yoke or permanent yoke magnetization should not be used. 9.2.4.2 When using the yoke method to magnetize the ferrule, if the end face of the ferrule is larger than the magnet The yoke end face should be magnetized segmentally along the ferrule end face, and the effective magnetization area should overlap by 10% each time.
9.2.4.3 When using the yoke method to magnetize rollers, the area of ??the fixture for mounting the rollers shall not be larger than the area of ??the yoke. 9.2.4.4 When using the yoke method to magnetize parts, high-density leakage flux will be generated locally at and near the contact area between the yoke and the part, and incoherent magnetic traces will appear, which should be eliminated by changing the direction of the magnetic poles. 9.2.5 Induced current method
This is a magnetization method that uses the part as the secondary coil of the transformer and causes the alternating magnetic flux to induce a circumferential current on the part. The magnetic field generated by the induced current is annular, and the ferrule can be found Circumferential defects on inner and outer walls and end faces. 9.2.5.1 When using the induced current method, except for the parts to be inspected, there must be no other conductors surrounding the magnetic field. 9.2.5.2 The induced current method generally uses alternating current, or current with a quick power-off device. When the power is cut off quickly, an inrush current with a very strong current value can be induced in the parts, and then the residual magnetism method is used to check. 9.2.6 Composite magnetization method
Apply two or more magnetic fields in different directions on the part at the same time. The direction of the synthetic magnetic field on the part continuously changes (forming a swing magnetic field or a rotating magnetic field). One magnetization is enough. Detect defects in multiple directions on the part. 9.2.6.1 There are many forms of composite magnetization. The following three types are commonly used for flaw detection of bearing parts: a. Induced current combined with a phase-shifted AC excitation current; b. Cross coil:
350||tt| |C. Circumferential magnetization by rod-through method and longitudinal magnetization of the yoke. JB/T 5391--91
9.2.6.2 The composite magnetization method can only be used for the continuous method and cannot be used for the residual magnetization method. 10 Magnetization specifications
10.1 Circumferential magnetization specifications
General rules for selection of circumferential magnetization specifications
10. t. 1
10.1.1.1 Cylindrical or round simple parts During circumferential magnetization, calculate the magnetizing current value according to formula (1): HD
320
Wuzhong: 1
magnetizing current intensity, A;
H-- Magnetic field strength, A/m;
1)
D-part diameter, mm.
10.1.1.2 The standard specification for circumferential magnetization stipulates that the magnetic field intensity on the surface of the part should reach 2400A/m (30Oe) when using the continuous method, and 8000A/m (100Oe) when using the residual magnetization method; for high stress, Parts working under high load conditions should adopt strict specifications. The surface magnetic field strength of the parts should reach 4800A/m (600e) when using the continuous method and 14400A/m (180Qe) when using the residual magnetization method. Relaxed specifications should be used for rough machining of rough parts. , when using the residual magnet method, the magnetic field intensity on the surface of the part should reach 6366A/m (80Oe). Those who have the conditions should measure and draw the magnetization curve according to the material and heat treatment status of the parts, and formulate magnetization specifications 10.1.2 Magnetization specifications for direct energization method and center penetration method 10.1.2.1 For locomotive axle parts and passengers working under high load conditions , the bearing parts of the vehicle axle of the truck adopt the following magnetizing current value:
Continuous method: 1 (15~18)D
Residual magnet method: 1 (30~~40)D|| tt||In the formula: I magnetizing current intensity, A (AC effective value); D-part diameter, mm (calculated as the outer diameter of the ferrule) 10.1.2.2 For bearing parts working in other parts, the following magnetizing current values ??are used: Continuous Method: 1=(10～15)D
Residual magnetization method: I(25～40)D
10.1.3 Offset mandrel method magnetization specifications
When using the continuous method , the magnetizing current value can be selected according to the table. The wall thickness of the part is mm
2~5
5~8
811
11~14
Note: For quarter parts with a wall thickness greater than 14mm, the magnetizing current increases by 250A for every 3mm increase in wall thickness. 10.2 Longitudinal magnetization specifications
Magnetizing current A
1000
1250
1500
1750
10.2.1 When the coil is magnetized, the patient should be considered Influence of the demagnetization factor of parts, the residual magnetization method selects the magnetic field intensity value according to the following principles: a.
h,
c
L/D≥10 parts, no-load coil The center magnetic field strength should be greater than 12000A/m (1500e); 23. When magnetizing through the rod method, multiple parts are allowed to be magnetized on the conductor at the same time, but it should be noted that there should be an appropriate distance between the parts. The parts at both ends of the conductor should be at least 15mm away from the chuck of the flaw detector. 9.2.2 Direct energization method
The magnetizing current passes directly through the part itself to generate a circumferential magnetic field inside or around the part. This method can find defects parallel to the direction of current flow, such as roller material cracks, axial rate fire cracks, etc. 9.2.2.1 When using the direct energization method, the current can pass along the axis of the part (axial energization method) or in the direction perpendicular to the axis of the part (right-angle energization method).
9.2.2.2 When directly energized, a clamp made of non-magnetic material is allowed to connect multiple rollers in series and magnetize them simultaneously. 9.2.3 Coil method
This method is to place the part in a solenoid coil carrying current and generate a longitudinal magnetic field in the part. This method can find defects perpendicular to the axis of the coil.
9.2.3.1 When the coil is magnetized, the degree of magnetization is related to the L/D value of the part (L is the length of the part, D is the diameter of the part). The larger the L/D, the easier it is to magnetize. Therefore, when magnetizing rollers, multiple rollers should be connected in series for magnetization. The I./D value after series connection should be greater than 5. 9.2.3.2 When the coil is magnetized, since the magnetic lines of force at both ends of the part are divergent, the magnetic field lines at both ends of the part are divergent. The flaw detection sensitivity of the end is reduced and the magnetic marks are blurred. The quick power-off method should be used to eliminate
9.2.3.3 When the inner diameter of the coil greatly exceeds the diameter of the part, the part should be magnetized close to the coil wall. Generally, the part axis should be parallel to the coil axis.
9.2.4 Magnetic Yoke Method
This method can generate a longitudinal magnetic field in the part by placing the part between the electromagnetic yoke or the permanent magnetic yoke. This method shows defects that are perpendicular to the magnetic field lines.
9.2.4.1 Under normal circumstances, AC yoke magnetization should be used for flaw detection of bearing parts. DC yoke or permanent yoke magnetization should not be used. 9.2.4.2 When using the yoke method to magnetize the ferrule, if the end face of the ferrule is larger than the magnet The yoke end face should be magnetized segmentally along the ferrule end face, and the effective magnetization area should overlap by 10% each time.
9.2.4.3 When using the yoke method to magnetize rollers, the area of ??the fixture for mounting the rollers shall not be larger than the area of ??the yoke. 9.2.4.4 When using the yoke method to magnetize parts, high-density leakage flux will be generated locally at and near the contact area between the yoke and the part, and incoherent magnetic traces will appear, which should be eliminated by changing the direction of the magnetic poles. 9.2.5 Induced current method
This is a magnetization method that uses the part as the secondary coil of the transformer and causes the alternating magnetic flux to induce a circumferential current on the part. The magnetic field generated by the induced current is annular, and the ferrule can be found Circumferential defects on inner and outer walls and end faces. 9.2.5.1 When using the induced current method, except for the parts to be inspected, there must be no other conductors surrounding the magnetic field. 9.2.5.2 The induced current method generally uses alternating current, or current with a quick power-off device can also be used. When the power is cut off quickly, an inrush current with a very strong current value can be induced in the parts, and then the residual magnetism method is used to check. 9.2.6 Composite magnetization method
Apply two or more magnetic fields in different directions on the part at the same time. The direction of the synthetic magnetic field on the part continuously changes (forming a swing magnetic field or a rotating magnetic field). One magnetization is enough. Detect defects in multiple directions on the part. 9.2.6.1 There are many forms of composite magnetization. The following three types are commonly used for flaw detection of bearing parts: a. Induced current combined with a phase-shifted AC excitation current; b. Cross coil:
350||tt| |C. Circumferential magnetization by rod-through method and longitudinal magnetization of the yoke. JB/T 5391--91
9.2.6.2 The composite magnetization method can only be used for the continuous method and cannot be used for the residual magnetization method. 10 Magnetization specifications
10.1 Circumferential magnetization specifications
General rules for selecting circumferential magnetization specifications
10. t. 1
10.1.1.1 Cylindrical or round simple parts During circumferential magnetization, calculate the magnetizing current value according to formula (1): HD
320
Wuzhong: 1
magnetizing current intensity, A;
H-- Magnetic field strength, A/m;
1)
D-part diameter, mm.
10.1.1.2 The standard specification for circumferential magnetization stipulates that the magnetic field intensity on the surface of the part should reach 2400A/m (30Oe) when using the continuous method, and 8000A/m (100Oe) when using the residual magnetization method; for high stress, Parts working under high load conditions should adopt strict specifications. The surface magnetic field strength of the parts should reach 4800A/m (600e) when using the continuous method and 14400A/m (180Qe) when using the residual magnetization method. Relaxed specifications should be used for rough machining of rough parts. , when using the residual magnet method, the magnetic field intensity on the surface of the part should reach 6366A/m (80Oe). Those who have the conditions should measure and draw the magnetization curve according to the material and heat treatment status of the parts, and formulate magnetization specifications 10.1.2 Magnetization specifications for direct energization method and center penetration method 10.1.2.1 For locomotive axle parts and passengers working under high load conditions , the bearing parts of the vehicle axle of the truck adopt the following magnetizing current value:
Continuous method: 1 (15~18)D
Residual magnet method: 1 (30~~40)D|| tt||In the formula: I magnetizing current intensity, A (AC effective value); D-part diameter, mm (calculated as the outer diameter of the ferrule) 10.1.2.2 For bearing parts working in other parts, the following magnetizing current values ??are used: Continuous Method: 1=(10～15)D
Residual magnetization method: I(25～40)D
10.1.3 Offset mandrel method magnetization specifications
When using the continuous method , the magnetizing current value can be selected according to the table. The wall thickness of the part is mm
2~5
5~8
811
11~14
Note: For quarter parts with a wall thickness greater than 14mm, the magnetizing current increases by 250A for every 3mm increase in wall thickness. 10.2 Longitudinal magnetization specifications
Magnetizing current A
1000
1250
1500
1750
10.2.1 When the coil is magnetized, the patient should be considered Influence of the demagnetization factor of parts, the residual magnetization method selects the magnetic field intensity value according to the following principles: a.
h,
c
L/D≥10 parts, no-load coil The center magnetic field strength should be greater than 12000A/m (1500e); 25 Induced current method
This is a magnetization method that uses the part as the secondary coil of the transformer and causes the alternating magnetic flux to induce a circumferential current on the part. The magnetic field generated by the induced current is annular and can be found on the inner and outer walls of the ferrule. and circumferential defects on the end face. 9.2.5.1 When using the induced current method, except for the parts to be inspected, there must be no other conductors surrounding the magnetic field. 9.2.5.2 The induced current method generally uses alternating current, or current with a quick power-off device can also be used. When power is cut off quickly, an inrush current with a very strong current value can be induced in the parts, which can then be inspected using the residual magnetism method. 9.2.6 Composite magnetization method
Apply two or more magnetic fields in different directions on the part at the same time. The direction of the synthetic magnetic field on the part continuously changes (forming a swing magnetic field or a rotating magnetic field). One magnetization is enough. Detect defects in multiple directions on the part. 9.2.6.1 There are many forms of composite magnetization. The following three types are commonly used for flaw detection of bearing parts: a. Induced current combined with a phase-shifted AC excitation current; b. Cross coil:
350||tt| |C. Circumferential magnetization by rod-through method and longitudinal magnetization of the yoke. JB/T 5391--91
9.2.6.2 The composite magnetization method can only be used for the continuous method and cannot be used for the residual magnetization method. 10 Magnetization specifications
10.1 Circumferential magnetization specifications
General rules for selection of circumferential magnetization specifications
10. t. 1
10.1.1.1 Cylindrical or round simple parts During circumferential magnetization, calculate the magnetizing current value according to formula (1): HD
320
Wuzhong: 1
magnetizing current intensity, A;
H-- Magnetic field strength, A/m;
1)
D-part diameter, mm.
10.1.1.2 The standard specification for circumferential magnetization stipulates that the magnetic field intensity on the surface of the part should reach 2400A/m (30Oe) when using the continuous method, and 8000A/m (100Oe) when using the residual magnetization method; for high stress, Parts working under high load conditions should adopt strict specifications. The surface magnetic field strength of the parts should reach 4800A/m (600e) when using the continuous method and 14400A/m (180Qe) when using the residual magnetization method. Relaxed specifications should be used for rough machining of rough parts. , when using the residual magnet method, the magnetic field intensity on the surface of the part should reach 6366A/m (80Oe). Those who have the conditions should measure and draw the magnetization curve according to the material and heat treatment status of the parts, and formulate magnetization specifications 10.1.2 Magnetization specifications for direct energization method and center penetration method 10.1.2.1 For locomotive axle parts and passengers working under high load conditions , the bearing parts of the vehicle axle of the truck adopt the following magnetizing current value:
Continuous method: 1 (15~18)D
Residual magnet method: 1 (30~~40)D|| tt||In the formula: I magnetizing current intensity, A (AC effective value); D-part diameter, mm (calculated from the outer diameter of the ferrule) 10.1.2.2 For bearing parts working in other parts, the following magnetizing current values ??are used: continuous Method: 1=(10～15)D
Residual magnetization method: I(25～40)D
10.1.3 Offset mandrel method magnetization specifications
When using the continuous method , the magnetizing current value can be selected according to the table. The wall thickness of the part is mm
2~5
5~8
811
11~14
Note: For quarter parts with a wall thickness greater than 14mm, the magnetizing current increases by 250A for every 3mm increase in wall thickness. 10.2 Longitudinal magnetization specifications
Magnetizing current A
1000
1250
1500
1750
10.2.1 When the coil is magnetized, the patient should be considered Influence of the demagnetization factor of parts, the residual magnetization method selects the magnetic field intensity value according to the following principles: a.
h,
c
L/D≥10 parts, no-load coil The center magnetic field strength should be greater than 12000A/m (1500e); 25 Induced current method
This is a magnetization method that uses the part as the secondary coil of the transformer and causes the alternating magnetic flux to induce a circumferential current on the part. The magnetic field generated by the induced current is annular and can be found on the inner and outer walls of the ferrule. and circumferential defects on the end face. 9.2.5.1 When using the induced current method, except for the parts to be inspected, there must be no other conductors surrounding the magnetic field. 9.2.5.2 The induced current method generally uses alternating current, or current with a quick power-off device can also be used. When power is cut off quickly, an inrush current with a very strong current value can be induced in the parts, which can then be inspected using the residual magnetism method. 9.2.6 Composite magnetization method
Apply two or more magnetic fields in different directions on the part at the same time. The direction of the synthetic magnetic field on the part continuously changes (forming a swing magnetic field or a rotating magnetic field). One magnetization is enough. Detect defects in multiple directions on the part. 9.2.6.1 There are many forms of composite magnetization. The following three types are commonly used for flaw detection of bearing parts: a. Induced current combined with a phase-shifted AC excitation current; b. Cross coil:
350||tt| |C. Circumferential magnetization by rod-through method and longitudinal magnetization of the yoke. JB/T 5391--91
9.2.6.2 The composite magnetization method can only be used for the continuous method and cannot be used for the residual magnetization method. 10 Magnetization specifications
10.1 Circumferential magnetization specifications
General rules for selecting circumferential magnetization specifications
10. t. 1
10.1.1.1 Cylindrical or round simple parts During circumferential magnetization, calculate the magnetizing current value according to formula (1): HD
320
Wuzhong: 1
magnetizing current intensity, A;
H-- Magnetic field strength, A/m;
1)
D-part diameter, mm.
10.1.1.2 The standard specification for circumferential magnetization stipulates that the magnetic field intensity on the surface of the part should reach 2400A/m (30Oe) when using the continuous method, and 8000A/m (100Oe) when using the residual magnetization method; for high stress, Parts working under high load conditions should adopt strict specifications. The surface magnetic field strength of the parts should reach 4800A/m (600e) when using the continuous method, and 14400A/m (180Qe) when using the residual magnetization method. Relaxed specifications should be used for rough machining of rough parts. , when using the residual magnet method, the magnetic field intensity on the surface of the part should reach 6366A/m (80Oe). Those who have the conditions should measure and draw the magnetization curve according to the material and heat treatment status of the parts, and formulate magnetization specifications 10.1.2 Magnetization specifications for direct energization method and center penetration method 10.1.2.1 For locomotive axle parts and passengers working under high load conditions , the bearing parts of the vehicle axle of the truck adopt the following magnetizing current value:
Continuous method: 1 (15~18)D
Residual magnet method: 1 (30~~40)D|| tt||In the formula: I magnetizing current intensity, A (AC effective value); D-part diameter, mm (calculated as the outer diameter of the ferrule) 10.1.2.2 For bearing parts working in other parts, the following magnetizing current values ??are used: Continuous Method: 1=(10～15)D
Residual magnetization method: I(25～40)D
10.1.3 Offset mandrel method magnetization specifications
When using the continuous method , the magnetizing current value can be selected according to the table. The wall thickness of the part is mm
2~5
5~8
811
11~14
Note: For quarter parts with a wall thickness greater than 14mm, the magnetizing current increases by 250A for every 3mm increase in wall thickness. 10.2 Longitudinal magnetization specifications www.bzxz.net
Magnetizing current A
1000
1250
1500
1750
10.2.1 When the coil is magnetized, the patient should be considered Influence of the demagnetization factor of parts, the residual magnetization method selects the magnetic field intensity value according to the following principles: a.
h,
c
L/D≥10 parts, no-load coil The center magnetic field strength should be greater than 12000A/m (1500e); 2
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