Sand casting technology of motor shell steel casting

The weight of the steel casting of the motor shell is 381kg, which is similar to the barrel structure. The wall thickness is uneven. The minimum thickness is 19mm and the maximum thickness is 110mm. There are multiple bosses on the outer cylinder and multiple stiffeners and connecting ribs on the inner cylinder. There are many sand casting hot spots and large crack tendency. The product structure and the names of various parts are shown in the figure:

① Chemical composition and physical and chemical properties of the product

The chemical composition is shown in the table. The content of chemical composition must ensure that the carbon equivalent CE ≤ 0.76%. [CE = C + 1 / 3 (Mn + CR) + 1 / 6 (Si + Ni) + 1 / 2Mo], the upper limit of Mn can be increased by 0.04% for every 0.01% reduction of carbon, but the total can not exceed 1%.

The main indexes of physical and chemical properties are: tensile strength RM ≥ 448 n / mm2, yield strength rel ≥ 241n / mm2, elongation a ≥ 24%, reduction of area Z ≥ 35%.

② Unmarked tolerance and surface quality requirements for sand casting dimensions

Unmarked tolerance of sand casting dimension: sfsa grade T-4; sand Casting surface quality requirements: ASTM 802 Ⅱ.

③ NDT requirements

The sand casting surface shall be subject to full fluorescent magnetic particle flaw detection according to ASTM 709, and the key areas of the sand casting shall be subject to ultrasonic flaw detection according to astm609.

④ Other requirements

Sand castings are not allowed to have cracks and sand inclusion defects.

B10 motor shell steel castings are an important product developed by ZHY Casting in cooperation with a foreign company. They are used on diesel locomotive motors operated in Europe and America. Each locomotive uses 12 pieces, with an annual demand of about 10000 pieces.

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