Analysis of four causes of fastener bolt fracture

1, assembly torque is too large, uneven force. Because there is no strict torque wrench in the assembly, and the specific torque is not known, the tighter the better; Fastening the connecting rod bolt with a long afterrod, the torque is too large, exceeding the yield limit of the bolt material, so that the connecting rod bolt yield deformation, so that the impact load under the action of excessive elongation and fracture. It should be emphasized that the connecting rod bolts must be tightened according to the standard, never think that the tighter, the greater the strength of the better.

2. The connecting rod of diesel engine is divided into many levels. Attention should be paid to not changing the connecting rod of different levels in maintenance. If in the maintenance due to careless careless connecting rod cover confusion, wrong installation, will cause the connecting rod big head with the surface is not close, in the engine operation will cause the connecting rod cover loose and lead to the fracture of connecting rod bolts. WD615 series diesel engine connecting rod big head is inclined cut type, inclined cut Angle is 45°, connecting rod cover and connecting rod big head using 60° sawtooth positioning structure, this structure has the characteristics of close fitting, accurate positioning, reliable, compact structure. If the connecting rod cover is messed up and wrongly installed in maintenance, it is bound to cause poor sawtooth positioning of the joint surface, which is easy to cause the loosening of the connecting rod cover in the work of the engine, and lead to the fracture of the connecting rod bolt.

3, the diesel engine in the operation of the fault or piston burning in the cylinder of the fault, the connecting rod bolt broken. If the engine in use has a flying fault, should do a comprehensive inspection of the engine, it is best to replace the connecting rod bolt; If there is a serious cylinder tension in the operation of individual cylinders, the connecting rod bolts should also be replaced when the cylinder piston assembly is replaced.

4. Material problems, processing defects and heat treatment process problems will also lead to the fracture of connecting rod bolts during engine operation.