Analysis and design of crankshaft shell casting process

Through research and production practice, the following key problems must be solved in order to produce high-quality and mass qualified castings by crankshaft shell iron shot casting:

(1) liquid shrinkage, solidification shrinkage, graphitization expansion and mold expansion during solidification of nodular iron, resulting in shrinkage porosity and shrinkage cavity casting defects in the casting; For the crankshaft, especially the main journal, connecting rod journal and the joint between the main journal and connecting rod journal and the fan plate, it is strictly prohibited to produce casting defects such as shrinkage porosity and shrinkage cavity in the casting. Therefore, in order to solve the casting defects of shrinkage porosity and shrinkage cavity, there must be a reasonable pouring system, riser feeding system and chilling at the hot joint, which are conducive to the simultaneous solidification of molten iron according to the design requirements. At the same time, the strength and thickness of the mold shell, the exhaust system during pouring, and Casting blank design, etc.

(2) fully filled and compacted iron shot is the key to ensure the quenching of the casting, avoid the size out of tolerance caused by mold expansion, prevent the internal shrinkage porosity, shrinkage cavity casting defects and molten iron leakage during pouring. Therefore, the iron shot filling and compaction process are also very important.

(3) due to the shape of the crankshaft, especially the crank part, in the vertical shell making and vertical pouring process, the qualified mold shell and iron shot filling shall ensure the large-scale shell making, iron shot filling and compaction. Therefore, the reasonable shell shape design shall ensure the smooth shell making and iron shot filling and compaction.

(4) high quality coated sand is the premise and foundation to ensure that the shell mold has high tensile strength, bending strength and low gas generation.

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