2022-04-11
The process discipline and casting process as well as operation process shall be seriously followed during the pipe mould in service. The lower limit of the casting temperature shall be taken in order to ensure the quality of the pipe mould. The pipe mould shall not be stopped rotating until the mould cooling to near room temperature in order to prevent the uneven heating of the mould; The pulling-out pipe number shall be controlled per circle and check regularly for maintenance. The following parts shall be noticed：
1. Usage of pipe mould powder
The role of mould powder is to prevent mould instant burning and to reduce the temperature of hot metal, and pull-out lubrication as well as inoculating degassing and so on. The theoretical addition amount is 25-35g/m2, and the amount can be increased by 1-2 items when the mould powder should be limited to ≥30g/m2 as shown in the following table.
2. Selection of pouring temperature
The aim of reducing the hot metal temperature is to reduce the heat storage and alternating thermal stress so as to prolong the service life of the pipe mould.
Pouring temperature control principle: On the premise of satisfying casting quality, the temperature of hot metal and the heat storage of pipe mould should be reduced as for as possible.
The pipe mould pouring should have scientific and reasonable pouring technology and management system. The operation process must be strictly executed, and the production record should be made in detail.
Process temperature of spheroidizing and sector ladle
The temperature of sectoer ladle is the pouring temperature. The temperature of DN 80—DN100 sector ladle can be controlled from 1390℃ to 1440℃. The larger the size , the lower the pouring temperature.
The hot metal temperature in the early stage of production is controlled by the lower limit, and by the middle limit in the middle and later stage. The hot metal temperature of the small diameter pipe mould shall be controlled by the upper limit, and the large diameter pipe mould is controlled by the lower limit. In practice, the pouring temperature of ductile iron is between 1320℃ (Large diameter) and 1380℃(small diameter).
The hot metal temperature shall be monitored in the production. The cooling measures (such as adding chilling blocks) must be taken if the temperature is too high, and over-temperature pouring is not allowed.
