At present, there are two main structures at the push rod hole of diesel engine cylinder head. One is that the push rod hole is formed by machining; The other structure is formed by direct casting of the push rod hole. The two structures have great influence on the casting process, and each has its own advantages and disadvantages. The specific analysis is as follows.
1. Forming of push rod hole
The structure formed by processing the push rod hole is common in the cylinder head of our high-speed diesel engine. The rough hole or solid with machining allowance is cast in the push rod hole. The push rod hole is formed by processing. Press the push rod bushing first, and then assemble the push rod, as shown in Figure 1.
The advantage of the structure formed by the processing of the push rod hole is that the casting structure is simple and easy to cast, and generally there is no interference in the assembly of the push rod hole. The disadvantage of the structure formed by the processing of the push rod hole is that if the casting here is a solid structure, it is easy to form hot joints. If the casting material requirements are high, it is easy to produce shrinkage defects.
2. Push rod hole casting structure
The push rod hole casting structure is common in the cylinder head of our large cylinder diameter diesel engine. The push rod hole is directly cast without processing, and the push rod is directly assembled in the later stage, as shown in Figure 2.
The advantage of the push rod hole casting structure is that the wall thickness of the casting is uniform, and it is not easy to produce casting defects. The push rod hole does not need to be processed and the bushing is pressed, which can save the cost.
The drawback of the cast-out structure of the push rod hole is that if the push rod hole is large and complex in shape, especially for large cylinder head, it is necessary to produce the push rod hole core separately and then assemble the core. Compared with the structure formed by the processing of the push rod hole, the position of the cast hole will be deviated due to various factors such as core assembly accuracy and casting shrinkage, which is easy to interfere in the later assembly.
3. Analysis and suggestions
According to the product requirements, corresponding process design shall be adopted for different forming methods of push rod hole.