Casting method of high-quality ship medium-speed series diesel front end box body

Abstract

The invention relates to a mechanical casting process, relates to a casting method of a high-quality ship medium-speed series diesel front end box body, and is characterized in that the casting method comprises the following specific steps: (1) molding and preparing a core; (2) smelting original molten iron: adopting 65% of pig iron, 35% of scrap steel, an alloy and a recarburizing agent as raw materials, overheating for 5 min at a melting temperature of above 1500 DEG C, carrying out pure purification of the molten iron, and controlling the original molten iron chemical composition to have the following content by the weight percentage: 3.0-3.1% of C, 1.1-1.2% of Si, 0.9-1.1% of Mn, not more than 0.10% of P, not more than 0.10% of S, 0.6-0.8% of Cu, 0.2-0.3% of Cr, and the balance being Fe; (3) carrying out first inoculation treatment; (4) carrying out secondary inoculation; and (5) pouring: carrying out pouring and the secondary inoculation simultaneously with the pouring speed of 35-40 kg / s, controlling the pouring time of 90-100 s, adding the pouring time of not less than 3 min after iron appears at a riser, and designing a pouring system as a double-layer ladder type. The casting method solves the problems that a conventional ship diesel front end box body casting method has many product defects and low finished product rate, and is especially suitable for the casting of the medium-speed series diesel front end box body.

Description

technical field [0001] The invention relates to the improvement of a mechanical casting process, in particular to a casting method for a high-quality marine medium-speed series diesel engine front end box body. Background technique [0002] The front end case is the most complex casting in the medium speed series diesel engine. Due to its large outline size (length*width*height: 2150mm*1550mm*900mm), thin wall of the main body (15mm), great difference in wall thickness (up to 150mm in the thickest part), and complex inner cavity structure (from the upper, middle and lower three There are more than 30 sand cores in total to form more than 10 oil chambers and water chambers), and the test pressure of each chamber is 1.0MPa, which is very difficult to cast. The problems existing in the existing casting method are: Good ventilation measures are not adopted in molding core making. The chemical composition of the original molten iron is C: 3.2 ~ 3.5%, Si: 1.6 ~ 1.8%, Mn: 0.8 ~ 1....

AI Technical Summary

Problems solved by technology

[0003] The purpose of the present invention is to solve the problems of casting the front-end box body of medium-speed marine diesel engine in the traditional method, with many product defects, poor quality and low qualified rate, and to provide a casting method for the front-end box body of high-quality marine medium-speed series diesel engine

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