Failure in the process of using coated sand production equipment
Coated sand is covered with a solid resin film or core sand before the surface of the molding sand is formed. Coated sand equipment is accompanied by the development of coated sand technology. At present, the domestic coated sand production line is divided into automatic and semi-automatic. With the development of my country''''''''s foundry technology, the application of coated sand production lines has become more and more extensive, and the production technology of coated sand has also been greatly improved. The amount of resin added at the end of the month is also low, and the volume of coated sand is small, which greatly reduces the production cost.
Qingdao Sanzhu Machinery Equipment Manufacturing Co., Ltd. relies on years of casting experience to summarize the faults and improvement measures in the process of using coated sand production equipment: 1. Poor venting of casting pore cores; resin sand has a large amount of gas or gas Inappropriate speed; incomplete curing of sand core. Improve the exhaust system and improve the exhaust effect; use high-concentration or coarser raw sand; use low-gassing coated sand. 2. The core surface is loose: the core shooting pressure is too high or too low; the mold exhaust is not smooth; the mold runs out of sand due to the large gap of the box surface; the coated sand has poor fluidity or poor air permeability. Use reasonable sand injection pressure to improve the exhaust system to prevent holding of breath; use small deformation materials as the core box. 3. The core deformation, fracture, uneven heating of the mold, or the large difference in core wall thickness, resulting in inconsistent shrinkage during cooling; deformation of the core fork or uneven storage of the sand core; poor high-temperature performance of coated sand; excessive pouring pressure to improve mold structure , To make the temperature distribution uniform; use forming trays to store sand cores; use resins with low curing shrinkage; use high-temperature resistant and low-expansion coated sand; improve the pouring system to use pressureless. 4. The bright carbon generated by the poor phenolic resin on the surface of the casting floats on the surface of the molten iron at high temperatures, and wrinkles appear on the surface of the casting when solidified. Add about 2% iron oxide powder, use raw sand with high thermal conductivity; paint the surface of the shell core; add special auxiliary materials to the coated sand. 5. The resin in the shrinkage porosity coated sand inside the casting burns to generate heat at high temperatures, which slows down the solidification rate of molten iron and causes shrinkage porosity. Use chilled coated sand; put inner cooling iron in the shell core. 6. Shelling: The mold design is unreasonable and the temperature of the core box is uneven, which makes the low-temperature parts have low strength and shelling; the coated sand has low melting point, slow curing speed, and low thermal strength. Improve the mold structure to make the temperature distribution uniform; select resins with high melting point, fast curing speed and high thermal strength.