Causes of cracks in the cylinder of excavator accessories
The crack-prone parts of the engine cylinder block and cylinder head are usually related to its structure. Crack-prone sections of different types of engines have their own rules. Engine blocks and cylinder heads are usually cast in gray cast iron, alloy cast iron and aluminum alloys. Its structure is complex, and it works under high temperature, high pressure, heat load and alternating load during operation. As a result, sand holes and cracks often appear in the cylinder block and cylinder head.
The solution to the cracks in the cylinder of the excavator accessories
The engine is powerful and fast. At high speed, the inertial force is large, the stress on the bottom plate is large, and cracks are prone to appear.
The cylinder block has complex structure and uneven wall thickness. Due to its low stiffness, it is prone to cracks in some weak parts.
At high speeds, the crankshaft vibrates, which increases the load on the cylinder block and causes cracks in weak parts.
Stress concentrations will occur at the transition between machined parts and unmachined parts of different wall thicknesses. When the stress concentration is superimposed on the residual internal stress in casting, cracks are prone to occur.
If the engine runs under overload for a long time, the stress in the cylinder block will be too large, and the proportion of cracks in the cylinder block will be too large.
Sudden addition of cold water to the engine at high temperatures causes excessive thermal stress on the cylinder block, causing the cylinder block to deform and crack.
Excessive thickness of water dirt in the water jacket will reduce the passage of cooling water. At the same time, due to the poor heat transfer of water and sewage, the heat dissipation performance of the engine is reduced, especially after the water channel between the cylinder and the valve is blocked, it seriously affects its heat dissipation, and the temperature rises when the local work is running, and the thermal stress is too large . It is easy to appear in the severe winter season, and it will erupt due to the sudden increase of high temperature hot water.
The technical requirements of the repair work are not strictly implemented, such as the cylinder head bolts and torques are not tightened in the specified order, and the tightening force is uneven, resulting in deformation of the cylinder and cracks near the bolt holes.