Study on the casting technology of nodular cast iron into cylinder

According to the analysis of the casting structure and key casting technology difficulties of the intake cylinder, this paper mainly focuses on the theoretical research, design and calculation of the core casting technology scheme and process of the intake cylinder, and determines the final optimization process technology scheme.

In the research on the formation mechanism of surface defects of the intake cylinder casting, the flow characteristics of the pouring process of nodular cast iron were fully analyzed. The causes of slag inclusion on the surface of the casting were qualitatively analyzed by means of scanning electron microscope, energy spectrum analysis and experimental verification, and the theoretical research on prevention and control measures was carried out. In the research of forming mechanism of shrinkage cavity and porosity in intake cylinder, combined with the proportional solidification characteristics of nodular cast iron, the causes of shrinkage cavity, shrinkage porosity and microstructure defects were analyzed by using magma simulation criterion, and the process measures conforming to the balanced solidification of inlet cylinder castings were proposed.

The composition of the casting is closely related to the alloy type, solidification characteristics and casting structure of the casting. The determination of chemical composition and melting process is one of the important casting technologies. The research and determination of chemical composition of intake cylinder casting is carried out according to fcd450 material, technical requirements, raw and auxiliary materials, smelting equipment, etc. The main procedures for the study of conventional casting composition and melting process parameters include: material performance characteristics research, solidification characteristics analysis, chemical composition setting, melting requirements and furnace pretreatment technology research, molten iron quality detection and control, selection and determination of relevant process parameters, etc. In the aspect of chemical composition research, the influence trend of composition on shrinkage porosity and metallographic structure defects was mainly investigated. The comparison test block with different element content was prepared to study the shrinkage porosity tendency By means of inspection, metallographic analysis and physical and chemical property test, the factors influencing the defects such as shrinkage cavity and porosity, graphite floating and abnormal graphite distortion are analyzed and studied to determine the optimal casting composition ratio and melting process parameters to meet the quality requirements of the intake cylinder casting.

The research and design of casting technology is carried out according to the casting production batch, technical requirements and equipment capacity. The final process directly affects the defect prevention and control, production efficiency and manufacturing cost of castings. The conventional casting process research and design program mainly includes: process scheme research and determination, important process parameters determination, sand core design, gating system design, riser and chill research and design, casting process simulation and optimization. In addition to the conventional design content, the casting technology research also carried out important research on the prevention and control of casting slag inclusion and shrinkage porosity

(1) The mechanism of the influence of gating system on the surface slag inclusion defect of the intake cylinder casting was studied. With the aid of magma simulation analysis, the scheme design and optimization of slag avoiding gating system were completed.

(2) The formation mechanism and influencing factors of shrinkage cavity and porosity were studied. Different feeding systems, chill quenching and other balanced solidification technology schemes were set up Finally, the process effectiveness analysis and optimization were completed through the practical production verification to ensure the dense structure of the casting body.

The casting technology of intake cylinder casting is studied step by step. The experiments and researches of these key technologies are carried out in combination with furan resin sand molding technology, complex and difficult casting molding operation technology, ductile iron material melting technology, ductile iron casting casting pouring operation technology, casting and material analysis and detection technology and other core engineering technologies. The important research results are based on the control scheme for systematic analysis and experimental research, in order to fully verify the scientificity and feasibility of the designed casting technology scheme, and ensure that the optimized final casting technology scheme can meet the requirements of manufacturing high-quality castings.

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