In order to facilitate statistics, the location of crack casting defects is numbered and marked according to figure 1. Table statistics of crack and casting defect location of V-type engine block in four months of production.
It can be seen from the statistical data that the probability of hot crack casting defects on the right side is much higher than that on the left side, with a ratio of 2.4:1; In addition, hot cracks and casting defects appeared on the left and right sides of one machine body. According to the time analysis, the probability of hot crack casting defects is not balanced, but four and six hot crack casting defects were found on August 13 and September 11, respectively, which are relatively concentrated, and the crack casting defect rate is 50%.
According to the statistics of the relative position of crack casting defects (as shown in Figure 2), hot crack casting defects are mainly concentrated in the middle two gears, accounting for 72.2%, especially 15 pieces in the third gear, with an incidence of 41.7%.
Through the comparative investigation and analysis of molten iron chemical composition, furnace pretreatment and pouring, the influence of molten iron composition fluctuation on hot crack casting defects is eliminated.