Sand casting method for closed impeller of centrifugal pump with low specific speed

Abstract

The invention relates to a sand casting method for a closed impeller of a centrifugal pump with a low specific speed. An adopted sand casting mold comprises a lower mold, a lower sand box, an upper mold, a middle sand box, an upper sand box, a runner, a sprue, a sprue hole, ingates, a positioning pin sleeve, a positioning pin and an impeller cavity, and after the sand casting mold is adopted for casting, molding is carried out and a loam core is placed, during casting, molten iron vertically flows in from the sprue (7), passes through a transverse runner and a vertical sprue on the upper mold, and then flows into two cavities from ingates which are transversely separated on the two sides respectively. Compared with the prior art, due to the fact that the sprue and the runner are additionally arranged, after the flowing-in path of molten iron is increased, the flowing-in speed of the molten iron can be slowed down, and meanwhile the flowing-in time of the molten iron is prolonged, gas in an impeller cavity can be exhausted in time, the molten iron flows into a gas exhausting cavity, the casting foaming phenomenon can be effectively avoided, and the quality stability is good.

Description

technical field [0001] The invention relates to a sand casting method for a centrifugal pump impeller, in particular to a sand casting method for a closed impeller of a low specific speed centrifugal pump. Background technique [0002] With the improvement of energy saving, environmental protection and safety requirements, more and more centrifugal pumps with small flow rate and high head and low specific speed are used. The impellers of this type of centrifugal pump are generally made of cast iron, with a closed structure and an upper cover and a lower cover. The middle is the water outlet channel, and the modeling adopts clay sand technology, aluminum alloy mould, two boxes of wooden sand boxes, and the lower resin sand or coated sand mud core. Due to the upper cover plate and the lower cover plate, the resin sand or coated sand mud core forming the blade should be placed during molding. In this way, the air in the cavity is not discharged smoothly during pouring, and it ...

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Problems solved by technology

[0004] The present invention aims at the situation that the molten iron inflow path is relatively close due to the molding of the two boxes, the inflow speed is relatively fast, the time for inflow into the cavity is short, and the gas in the cavity cannot be discharged in time and effectively during the pouring after the above molding, and provides a The low specific speed centrifugal pump closed impeller sand casting method abandons the traditional thinking of finding how to exhaust air as soon as possible, and creatively proposes to extend the path of molten iron inflow, so that the gas in the cavity has time to discharge

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