JB/T 7367-1994 Magnetic particle testing method for cylindrical helical compression springs
Some standard content:
Mechanical Industry Standard of the People's Republic of China
JB/T7367-1994
Cylindrical helical compression spring
Magnetic particle inspection method
Published on July 26, 1994
Ministry of Machinery Industry of the People's Republic of China
Implementation on July 1, 1995
Mechanical Industry Standard of the People's Republic of China
Cylindrical helical compression spring
Magnetic particle inspection method
Subject content and scope of application
This standard specifies the magnetic particle inspection method for cylindrical helical compression springs, JB/T7367-1994
This standard is applicable to magnetic particle inspection of cylindrical helical compression springs with wire diameter d>2mm, including magnetic particle inspection of special-shaped wire springs. 2 Reference standards
GB3721
GB9445
3 Code
Magnetic particle flaw detector
General rules for technical qualification appraisal of non-destructive testing personnel Magnetic particle flaw detection method for internal combustion engine parts
3.1 Direct current method
The direct current method is a magnetization method in which a steel workpiece is placed between the two chucks of the flaw detector and an electric current is passed directly through the workpiece to be inspected. 3.2 Center conductor method
The center conductor method is a magnetization method in which a conductor is inserted into the hole of the workpiece to be inspected and an electric current is passed through the conductor. 3.3 Continuous method
A method in which magnetic powder or magnetic suspension is applied to the workpiece to be inspected under the action of an external magnetic field for flaw detection. 3.4 Residual magnetism method
A method of flaw detection by applying magnetic suspension to the workpiece to be inspected after cutting off the magnetizing current or removing the external magnetic field. 3.5 Demagnetization
The process of restoring the workpiece in the magnetized state to the non-magnetized state. 3.6 Ultraviolet rays
Electromagnetic radiation with a wavelength of 320~400nm.
3.7 Fluorescent magnetic powder
Magnetic powder treated with fluorescent substances that emits yellow-green light under ultraviolet light. 3.8 Magnetic suspension
Suspension containing magnetic powder.
3.9 Carrier liquid
Liquid used to suspend magnetic powder.
3.10 Magnetic writing
When two magnetized workpieces are rubbed against each other or a steel block is used to scratch a magnetized workpiece, magnetic changes will occur at the contact point and false magnetic powder traces will be produced. This phenomenon is called magnetic writing. Approved by the Ministry of Machinery Industry on July 26, 1994
Implemented on July 1, 1995
4 Flaw Detection Personnel
JB/T 73671994
Personnel engaged in magnetic particle flaw detection of springs must undergo professional training and obtain qualification certificates from relevant departments after assessment in accordance with the provisions of GB9445, otherwise they shall not be allowed to take up their posts.
5 Flaw Detection Device
5.1 Magnetization Device
5.1.1 The performance indicators of magnetic particle flaw detectors shall comply with the provisions of GB3721. 5.1.2 For the inspection of springs produced in large quantities, it is recommended to use a fixed general-purpose flaw detector or a spring-specific flaw detector with a magnetization current of 1000~4000A; for the inspection of springs produced in small quantities or single pieces, a mobile magnetization device with the same current value can also be used. 5.2 Demagnetization device
5.2.1 The magnetic field strength at the center of the demagnetization coil should be greater than 20000A/m. 5.2.2 The residual magnetism of the spring shall be checked by a magnetometer or other residual magnetism inspection instrument. 6 Flaw detection materials
6.1 Magnetic powder
6.1.1 Use non-fluorescent magnetic powder (black is ferroferric oxide, red is ferric oxide) with a mesh size of 300 or more and fluorescent magnetic powder with a mesh size of 400 or more.
6.1.2 The magnetic weighing of non-fluorescent magnetic powder shall be 7~9g; the magnetic weighing of fluorescent magnetic powder shall be 6~8g (fluorescent magnetic powder by bonding method). 6.2 Magnetic suspension
6.2.1 Oil-based carrier liquid
6.2.1.1 The oil-based carrier liquid of non-fluorescent magnetic powder shall use transformer oil or mixed oil (transformer oil + kerosene, in a ratio of 4:1). The kinematic viscosity of the oil at room temperature should be 1.0×10-5~2.0×10-5m2/s. 6.2.1.2 The oil-based carrier liquid of fluorescent magnetic powder adopts odorless kerosene, and its flash point should be greater than 90℃. 6.2.2 Water-based carrier liquid
The water-based carrier liquid formula should contain rust inhibitor, dispersant, defoaming agent, and have wetting and rust prevention functions for the workpiece. 6.2.3 Magnetic suspension concentration
The working magnetic suspension concentration of non-fluorescent magnetic powder is 15~25g/L; the working magnetic suspension concentration of fluorescent magnetic powder is 1~3g/L. 7 Technical requirements for flaw detection
7.1 Flaw detection method
7.1.1 Generally, the continuous method is used for inspection, and the residual magnetism method is allowed to be used for inspection. If the residual magnetism method is used for inspection, the magnetic properties of the spring material should meet the following requirements: B, ≥0.8T; H800A/m.
7.1.2 The spring after surface oxidation treatment should be tested with fluorescent magnetic powder or red non-fluorescent magnetic powder. 7.1.3 The illumination of the non-fluorescent magnetic particle flaw detection observation lamp on the workpiece surface should be greater than 15001x; the illumination of the ultraviolet lamp for fluorescent magnetic particle flaw detection observation should be greater than 9701x under the standard specification of 380cm. 7.1.4 The residual magnetism of the spring after magnetic particle flaw detection should be less than 0.2mT. 7.1.5 If the user has no requirements, the workpiece that has been magnetized in the circumferential direction may not be demagnetized. 7.2 Selection of magnetization method and magnetization current
The selection of magnetization method and magnetization current shall refer to the provisions of NJ320. Direct current magnetization (see Figure 1) is used to inspect the defects in the longitudinal direction of the spring (parallel to the axial direction of the steel wire); center conductor magnetization (see Figure 2) is used to inspect the defects in the transverse direction of the spring (parallel to the radial direction of the steel wire). 2
7.2.1 Continuous test
7.2.1.1 Direct current magnetization
JB/T7367-1994
Tested spring
Direct current magnetization
Tested spring
Center conductor
Figure 2 Center conductor magnetization
When the diameter of the spring steel wire is 2mm≤d<10mm, the magnetization current is selected according to the following formula: =(200±50)A
When the diameter of the spring steel wire is 10mm≤d≤20mm, the magnetization current is selected according to the following formula: =(20d±50)A
When the diameter of the spring steel wire is d>20mm, the magnetization current is selected according to the following formula: I=[（10~20)d)A
7.2.1 .2 Magnetization by center conductor method
When the spring center diameter D<20mm, the center conductor current is selected according to the following formula: I=（250±50）A
When the spring center diameter is 20mm≤D≤200mm, the center conductor current is selected according to the following formula: I=（20D±50）A
7.2.2 Residual magnetism test
7.2.2.1 Magnetization by direct current method
When the spring wire diameter is more than 2mm and d<10mm, the magnetization current is selected according to the following formula: I=(350±50)A
When the spring wire diameter is 10mm≤d≤20mm, the magnetization current is selected according to the following formula: I=(35d±50)A
When the spring wire diameter is d>20mm, the magnetization current is selected according to the following formula: I=[ (20~35) d]A
7.2.2.2 Center conductor magnetization
When the spring center diameter D<20mm, the center conductor current is selected according to the following formula: =(500±50)A
When the spring center diameter D≥20mm, the center conductor current is selected according to the following formula: 3
I=(45D±50)A
JB/T 73671994
7.2.2.3When AC magnetization is used, the equipment should be equipped with a power-off phase controller. 7.2.3When the spring center diameter D>200mm, the continuous method center conductor magnetization should be biased. The arc length distance for each inspection is 4 times the diameter of the copper rod, and the magnetization overlap area is 10%.
7.3 Detection sensitivity requirements
No matter which magnetization method is used, a sensitivity test should be performed before each shift of flaw detection. The method is to place the defect surface of the artificial defect type A test piece (or type C test piece, type D test piece) close to the standard spring (small springs use natural defect samples), and the defects should be clearly displayed. 7.4 Magnetization precautions
7.4.1 The spring should be cleaned before flaw detection, and non-conductive layers such as rust, oil, and paint are not allowed to exist. 7.4.2 The direct power-on method requires the magnetization current to be stable, and the spring should be clamped and magnetized as a single piece. If there is no special magnetization device to ensure that each part reaches the required current value, parallel clamping magnetization is not allowed. 7.4.3 The magnetization time is 1~3s/time for the continuous method; 0.5~1s/time for the residual magnetism method. 7.4.4
Spring magnetic particle flaw detection is generally carried out before shot peening. If there are special requirements, it can be carried out after shot peening. 7.4.5
Springs that are difficult to inspect using the central conductor method are allowed to use other non-destructive testing methods. 7.4.6
Composite magnetization is permitted for continuous inspection. : Defect identification and discrimination
8.1 Defect classification
8.1.1 Related defect magnetic traces
refers to the accumulation of magnetic traces caused by raw material defects and process defects (including cracks, folds, welding defects, non-metallic inclusions, hairlines, corrosion pits, scratches, etc.).
8.1.2 Non-related defect magnetic traces
refers to pseudo-defect magnetic traces caused by changes in workpiece cross-section, metal flow lines, work hardening, material component segregation, magnetic writing, etc. 8.2 Defect nature determination
8.2.1 Related defect magnetic traces are clearly displayed, and the magnetic powder is densely concentrated in a straight line, curve or mesh. 8.2.2 Non-related defect magnetic traces are generally loosely gathered with wide magnetic traces. 8.3 Judgment criteria
8.3.1 Crack magnetic traces appearing in any part of the spring should be treated as unqualified, and point-shaped defect magnetic traces with a diameter of less than 0.5mm are allowed to appear in no more than two places per square centimeter. The length and size of other defects can be agreed upon by the supply and demand parties. 8.3.2 Qualitative and quantitative analysis of magnetic traces of defects found by flaw detection can be performed with the aid of metallographic microscope for anatomical observation when macroscopic judgment is not possible. 9 Flaw detection record
Spring magnetic particle flaw detection should record the following aspects9.1 General situationRecord content
a. Workpiece name, quantity, specification, material, heat treatment status, surface status; b. Name and model of flaw detection equipment;
c. Concentration of magnetic suspension.
9.2 Flaw detection process record content
a. Inspection method (continuous method or residual magnetism method);4
b. Magnetization method;
c. Magnetization current value;
JB/T73671994
d. Type of standard sample (artificial defect standard test piece or natural defect sample) and sensitivity value. 9.3 Contents of flaw detection result record
a. Total number of inspected parts;
b. Number of unqualified parts;
c. Number of various types of defects;
d. The proportion of unqualified parts to the total number of inspected parts. 9.4 Other contents
a. Name of flaw detector;
b. Date and location of flaw detection.
Flaw detection record can be in table form.
Labor insurance benefits
Magnetic particle flaw detectors are exposed to harmful substances such as lead vapor, ozone, and ultraviolet rays, and should enjoy corresponding labor insurance benefits in accordance with relevant national regulations. Additional notes:
This standard is proposed and managed by the Machinery Standardization Research Institute of the Ministry of Machinery Industry. This standard is drafted by the Machinery Standardization Research Institute of the Ministry of Machinery Industry, Beijing Internal Combustion Engine Factory, and Shanghai Spring Research Institute. The main drafters of this standard are Zhang Xinlan, Chen Jiansheng, Ge Ruyuan, and Zhang Jun. 5
People's Republic of China
Mechanical Industry Standard
Cylindrical Helical Compression Spring
Magnetic Particle Inspection Method
JB/T73671994
Published and issued by the China Academy of Mechanical Science
Printed by the China Academy of Mechanical Science
(No. 2 Shouti South Road, Beijing
Postal Code 100044)
Sheet 1/2
Format 880×1230
Word Count 10,000
First Edition in February 1995www.bzxz.net
First Printing in February 1995
Print Quantity 1-500
Price 3.00 Yuan
Mechanical Industry Standard Service Network: http://www.JB.ac.cn66
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