Bucket teeth are the main vulnerable parts on shovels in open pit mines. The casting weight is 130kg, the material is ZGMnl3, and the outline size is 944mm * 300mm * 150mm. This kind of castings are usually produced by traditional sand casting process. Because there are many sand cores, complex working procedures, time-consuming and high requirements for the technical operation level of workers, it is difficult to clean up the burrs produced by the bucket teeth, and the waste rate is high. EPC has many advantages in technology and economy:
(1) Without core, core-making process and related equipment can be omitted.
(2) There is no parting surface and no clearance between cores, so there is no flash and burr on the casting.
(3) The dimension accuracy of the castings can be improved by reducing or even eliminating the inclination of the starting die, without taking into account the negative number of parting and the negative number of sand cores.
(4) Foaming die is easy to bond and assemble.
(5) Good working environment and low production cost.
In order to give full play to the advantages of EPC and improve the yield of the process, the method of group casting can be used to cast bucket teeth. Using bottom-pumped negative pressure sand box, 10 pieces are placed in one box, the cusp of bucket teeth is downward, parallel to each other in the inside of the sand box, and 5 pieces are placed on both sides of the runner. As shown in Figure 8-9, closed gating system is adopted without risers.
When pouring, first point straight runner, then pour smoothly and quickly, so that the molten steel is always filled with the gate cup until the end of pouring. In this way, EPS in the direct runner is rapidly vaporized and filled with molten steel in a short time, which can effectively prevent negative pressure suction gas from entering the mould cavity, and at the same time, a certain static pressure can be established in the pouring system, so that the molten steel is not easily involved in gas and residue in the filling process, which can effectively avoid defects such as blowhole, residue and so on, and at the same time, it can prevent waste caused by partial collapse of castings. Product.
The castings obtained by EPC have good shape and fully meet the requirements of geometrical size; the surface quality of the castings is good, without burrs, shrinkage and porosity, and no risers; the workload of cleaning and cutting is reduced by 50%; the yield of the castings is increased by more than 40% compared with the traditional sand casting.