First analyze the definition of the bolt: it is a cylindrical threaded fastener with a nut, a type of fastener consisting of a head and a screw (a cylinder with an external thread), which needs to be matched with a nut. Used to fasten and connect two parts with through holes. The following is a description of the reasons why diesel engine connecting rod bolts are usually easy to break.
The connecting rod bolts of diesel engines are single-use and are not allowed to be reused. If the connecting rod bolt is repeatedly used, the bolt is elongated due to the large force, which may cause the bearing bush to burn due to insufficient bolt fastening strength; at the same time, due to insufficient fastening force, the matching gap between the bearing bush and the crankshaft journal The increase causes the oil pressure to be low, causing excessive wear of the bearing bush and causing a burnt tile accident. The diesel engine is a high-strength diesel engine. The connecting rod is subjected to a large impact load, which is much larger than that of an ordinary diesel engine. Repeated use of the connecting rod bolt can easily cause breakage and damage the engine cylinder block, resulting in the engine being scrapped. Some units have broken the joints despite the replacement of the connecting rod bolts. Some of the connecting rod bolts suddenly break during operation.
The cause of the failure:
1 When the assembly is too tight, the torque is not uniform. Since there is no strict torque wrench in the assembly, the specific tightening torque is not well understood, and the tighter the better; the longer tightening rod for tightening the connecting rod bolt, the tightening torque is too large, exceeding the bolt material The yield limit causes the connecting rod bolt to yield deformation so that it breaks due to excessive elongation under the impact load. It should be emphasized that the connecting rod bolts must be tightened according to the standard. Do not think that the tighter the strength, the better.
2 The connecting rods of diesel engines are divided into various levels. During maintenance, care should be taken not to switch to different levels of connecting rods. If the sloppy handle is messed up or misplaced during the overhaul, the joint of the big joint of the connecting rod will not be tightly fitted, and the connecting rod cover will loosen during the engine running, which will cause the connecting rod bolt to break. The connecting rod of WD615 series diesel engine is obliquely cut, the chamfer angle is 45°, and the joint surface of the connecting rod cover and connecting rod adopts 60° zigzag positioning structure. This structure has close fitting, accurate positioning, reliability and compact structure. specialty. If the connecting rod cover is messed up and misplaced during maintenance, it will inevitably result in poor positioning of the joint surface serration, which may easily cause the loosening of the connecting rod cover during the operation of the engine, resulting in the breakage of the connecting rod bolt.
3 The diesel engine has a fault in the running or the piston is burned in the cylinder during operation, and the connecting rod bolt is broken. If the engine has a fault in the running, the engine should be fully inspected. It is best to replace the connecting rod bolts. If there are serious cylinders in the individual cylinders during operation, the connecting rods should also be replaced when replacing the cylinder piston assembly. Bolt replacement.
4 Material problems, machining defects and heat treatment process problems can also cause the connecting rod bolts to break during engine operation.
The above original from: Shenzhen Chuanggu screw Zhu manager 15818603477 QQ956914748 http://
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