Sand casting of dredge pump body

China’s dredging industry has a long history. As early as the spring and Autumn period and the Warring States period, the huge project of digging artificial canals began, and some still play an important role, such as Dujiangyan, Beijing Hangzhou Grand Canal, Lingqu in Guangxi, etc. Traditional dredging operations mainly include port construction and maintenance, dredging of drainage system, dredging of channel, etc. However, with the continuous development of economy and technology, dredging projects expand to the ocean, and the demand for marine dredging projects continues to increase, such as marine infrastructure, hydraulic reclamation, offshore mining, marine environmental protection projects, etc. With the diversification of dredging projects, the requirements for dredging equipment are becoming higher and higher.

As the most important dredging equipment, dredger directly affects the benefits of dredging engineering. After long-term development and evolution, dredgers have formed two categories: mechanical type and hydraulic type. The mechanical type mainly includes grab type, bucket type and chain bucket type. The main feature of their operation is to use excavation machines and tools for dredging, conveying and unloading. The hydraulic type mainly includes rake suction type, bucket wheel type, suction type and winch suction type, During operation, they can carry out long-distance transportation of excavation media with the help of ship self navigation or hydraulic power, and can continuously carry out dredging, transportation and discharge at the same time, which can better meet the needs of the development of large-scale dredging engineering. At the same time, in order to meet the diversified needs of dredging projects, in recent years, water jet dredgers, pneumatic dredgers and environmental protection dredgers have been developed according to the specific media and construction conditions during dredging.

Cutter suction dredger accounts for the largest proportion of all kinds of dredgers. It is a combination of mechanical and hydraulic. It uses cutter to cut soil layer and mud pump to transport mud. It originated from the United States and has a development history of more than 100 years. Due to its large excavation depth and low requirements for soil quality, it can carry out dredging, transportation, discharge and mud treatment at the same time for a long time and high efficiency, Therefore, it has been widely used in engineering. Its working principle is relatively simple. It mainly relies on the centrifugal pump to provide energy, sucks the mud through the mud suction pipe, and finally transports the sucked mud to the destination through the mud discharge pipe. The mud pump is composed of pump body, impeller and other components. It is the most critical part of the mud conveying system. Its operation stability can directly affect the efficiency and operation cost of dredging construction. Dredgers often operate in very complex and harsh environment. Sediment and other particles will cause serious wear to the dredge pump, reduce the quality and performance of each part of the dredge pump and affect the stability of the operation of the dredge pump. The sand casting dredge pump body studied is the core flow passage part of the dredge pump. The quality of sand casting directly affects the service life of the dredge pump and the overall working efficiency of the dredger.

At present, there is still a huge gap between China and the world’s advanced countries in the research and manufacturing of large pump casing, and there is still a lack of systematic research on the wear mechanism and design method of sludge pump. Compared with the imported pump casing, the domestic pump casing has many shortcomings, its wear resistance is poor, resulting in fast wear and short service life; Cavitation is obvious, and it is easy to cause serious uneven wear during continuous operation, resulting in cavitation pits, increase overflow resistance, reduce the working efficiency of pump casing, and even perforation of pump casing in serious cases, resulting in sudden accidents; The backward maintenance technology results in the significant reduction of the dimensional accuracy of the pump casing channel and large deformation after maintenance, which seriously affects the working efficiency of the pump casing. How to significantly improve the manufacturing quality of the dredge pump body and increase its service life has become one of the core technical problems urgently to be solved in the domestic dredging industry.

Recently, the rapid development of sand mold casting CAE technology has greatly changed the sand mold casting technology which depends heavily on experience to modern and scientific. Numerical simulation can effectively analyze various physical and chemical phenomena in the process of sand casting, and make us deeply understand the details of fluid flow, heat transfer and metal solidification in the process of sand casting. The simulation results can characterize the transient flow characteristics (such as temperature and velocity) and the quality of sand castings (such as shrinkage porosity and grain structure), and accurately predict the changes of fields (such as temperature field, flow field and stress field) in each stage of sand casting process, So that engineers can observe and quantify those parameters that are invisible or unmeasurable in the actual sand casting process in advance in the process design stage, accelerate the design process, optimize the sand casting process parameters, significantly improve the quality of sand castings, and realize green sand casting with low investment and low energy consumption.

Therefore, in the sand mold casting process design stage of the mud pump body, using the simulation software to calculate the sand mold casting process can not only significantly reduce the possibility of sand mold casting defects and improve the sand mold casting quality of the mud pump body, but also shorten the development cycle of the mud pump body and save the R & D cost.

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