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Fig. 1. Data points from 3-ram tests indicated compactibility began fluctuating more than normal in July 2014.


cal issues in the system, after which the system went back into control. Te chart plotted from the automatic tester over the same period confirmed the variation trend indicated by the 3-ram tests (Fig. 2). Sand system tests and results can be used in the same way. Te


histogram from a test in Fig. 3 shows how many tests ran in an eight-hour time period. In this case, 197 tests ran in eight hours, 94 of which were +/-2 points from the target and 192 of which were +/-3 points from the target. Tests on compactibility should be performed daily to quantify and identify variation within the system. Compactibility can be improved by reducing the variation of


return sand conductivity or moisture. Figure 4 shows the conduc- tivity fluctuations from muller batch to muller batch on one of Grede-St. Cloud’s molding lines. Te wide fluctuations occurred through October 2012 and then became much tighter in the following months. Te improvement stemmed from the purchase of a new piece of equipment to replace a cooler moisture addition system that was not adding the right amount of water. Te data shows the new equipment made a positive impact on return sand


图1. 从3锤制样机检测的数据看出从2014年7月开始可紧实性的 波动超过正常值。


数据所表示的变化趋势(图2)。


测试及其结果可以以相同的方式使用。图3是由试验 得到的柱状图,表明8小时周期内得出多少测试结果。 在这个示例中,8小时共测得197个数值,其中94个数 值与目标值偏差+/- 2个点,192个数值与目标值偏差 +/-3个点。可紧实性的测试应每天进行,以便量化和识 别系统内参数的变化。


可紧实性可以通过降低回用砂电导率或含水量加以提 升。图4是Grede-St. Cloud公司的一条造型线每次混砂 的型砂导电率的波动情况。2012年10月发生过大幅波 动,然后在接下来的几个月变化的幅度小的多。这种改 善是由于购买了新的设备以替换原来的不能准确补水的 设备。数据显示新设备对回收砂电导率有明显的影响, 这通常会改善造型线上的可紧实性。


检查粘土含量 影响湿型砂质量第二个关键的独立变量是型砂中活性


Fig. 2. Data points from the automatic tester at the muller confirmed the fluctuation revealed by the 3-ram tests.


图2. 混砂机自动测试仪的数据波动证实了3锤制样机检测 的数据。


June 2015 FOUNDRY-PLANET.COM | MODERN CASTING | CHINA FOUNDRY ASSOCIATION | 63


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