According to the aboveprocess and operation points, after the brand of the four-way elbow valve box was changed to silicon brass ZCuZn16Si4, a total of more than 30 sand castings were produced with good quality, which can basically meet the technical requirements of 4.5 MPa hydraulic test for the four-way elbow valve box, and the leakage rate during the hydraulic test is less than 3%.
(1) For sand casting four-way elbow valve box, we should focus on solving several problems: first, it is difficult to demould; Second, it is more difficult to supplement; Third, oxidation inclusions are difficult to surface; Fourth, it is difficult to support and locate the sand core; Fifth, the gas in the sand core should be discharged smoothly.
(2) For sand casting four-way elbow valve box, mold lifting is the primary consideration. The outer mold is divided horizontally and the upper and lower round flanges are deactivated. In addition, it is also necessary to set up a sand core head to facilitate the core lowering of the main sand core. For the sand core, it is necessary to consider the support function and easy positioning, as well as the exhaust problem.
(3) For sand casting quadruple elbow valve box, the top round flange is generally supplemented by its own riser; One side of the middle flange is fed with a dark riser, and the other side is quenched with graphite chill; The round flange under the elbow and some parts of the valve box inner cavity are quenched with graphite chill iron.