This standard specifies the magnetic particle inspection and assessment methods for internal combustion engine connecting rods. This standard is applicable to the magnetic particle inspection and evaluation of forged steel with frost for reciprocating piston internal combustion engines with a cylinder diameter less than or equal to 200mm. JB/T 6722-1993 Magnetic particle inspection of internal combustion engine connecting rods JB/T6722-1993 Standard download and decompression password: www.bzxz.net

Machinery Industry Standards of the People's Republic of China
Magnetic Particle Flaw Inspection of Internal Combustion Engine Connecting Rods
Subject Content and Scope of Application
This standard specifies the magnetic particle testing and assessment methods for internal combustion engine connecting rods. JB/T 6722--93
This standard is applicable to the magnetic particle inspection and evaluation of forged steel connecting rods of reciprocating piston internal combustion engines with a cylinder diameter less than or equal to 200mm.
2 Reference Standards
NJ320 Internal Combustion Engine Parts and Components Magnetic Particle Flaw Inspection Methods Flaw Detection Methods
3
According to the provisions of NJ320, it is recommended to use fluorescent magnetic particle inspection. The division of the connecting rod surface area
4
is as specified in Table 1 and as shown in Figure 1.
Table 1
District Category
I District
District
National District
LE
Location and Range|| tt||Shaft part AD
Small head part DE
Big head hole inner surface
Big head part FA
IA
Ministry of Machinery Industry of the People's Republic of China 1993-07-29 Approved chart description
a.AD- BC+2×0. 1X BC
bB and C are the intersection or tangent points of the shaft and the large and small head round necks. The microcephaly includes all parts b of the entire microcephaly. The calculated length of the small head part is DE
The calculated length of the inner surface of the big head hole is the inner diameter of the big head hole a. The big head part includes all parts except the inner surface of the big head hole b. The calculated length of the big head part is FA||tt ||11
Slimming grape horn
-tangential point or intersection
Figure
1994-01-01 implementation
405
5
Classification of magnetic marks
The classification of magnetic marks is specified in Table 2.
Category
8. Transverse magnetic markswww.bzxz.net
Class A
Class B
Class C
Determination of magnetic thinness||tt| | 6 | | tt | C. Dense magnetic traces | Marks 6.1 When the angle between the magnetic marks on the connecting rod and the streamline direction of the workpiece is greater than 30°, it is a transverse magnetic mark. 6.2 When the distance between two defective magnetic marks on the same straight line is less than or equal to 2mm, they shall be treated as one defective magnetic mark. 6.3 In a square of 10mm × 10mm, those with more than 3 defective magnetic marks are dense defective magnetic marks. 6.4C type magnetic marks are not regarded as defective magnetic marks.
7 Defect magnetic sputum allowable limit value
7.1 Process defects such as parting line cracks, heat treatment cracks, grinding cracks, corrosion or pickling cracks are not allowed in any area. 7.2 No defective magnetic marks are allowed in the rounded corners of the shaft tendons and the rounded corners connecting the big and small heads to the shaft. 7.3 In zone I, except for the Class B magnetic marks that are allowed to have a length less than 1/1201 zone length and less than or equal to 4mm, which are parallel to the longitudinal axis of the forging and do not enter the connection between the shaft and the big and small heads (BC point), no magnetic marks are allowed. Defect magnetic marks are allowed. 7.4 In Zone II, each part is allowed to have one or two Class B magnetic marks whose cumulative length does not exceed 1/20 of the length of the part. Class A magnetic marks are not allowed.
7.5 In zone III, one or two Class B magnetic marks with a cumulative length not exceeding 1/15 of the length of the part are allowed, and Class A magnetic marks are not allowed.
7.6 Only one defective magnetic mark is allowed to exist on the same cross-section perpendicular to the direction of the workpiece streamline direction. 8. Repair of defects
8.1 Class A and B defects are allowed to be repaired within the dimensional tolerance range or within the repairing range of damaged connecting rods. The machined surface part is allowed to be repaired within the dimensional tolerance range.
8.2 The trimmed connecting rod should have a smooth and smooth transition. After surface strengthening treatment, it should be inspected and accepted again. 9 Demagnetization
After the connecting rod undergoes magnetic particle inspection, it must be demagnetized, and the residual magnetic field strength shall not be greater than 2×10-\T. Additional notes:
This standard is proposed and administered by the Shanghai Internal Combustion Engine Research Institute of the Ministry of Machinery Industry. This standard is drafted by the Shanghai Internal Combustion Engine Research Institute of the Ministry of Machinery Industry. The main drafter of this standard is Weng Zuliang.
From the date of implementation of this standard, NJI319--84 "Technical Conditions for Magnetic Particle Flaw Detection of Internal Combustion Engine Connecting Rods" is invalid. 406
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