The section shape of gating system runner mainly refers to the section shape of ingate and cross runner. The cross-section shape of runner is dome trapezoid, accounting for 97%; the cross-section shape of ingate is flat rectangle, accounting for more than 90%. As shown in Figure 1.
The cross-section area of the trapezoidal runner with dome is large, with good skimming property and good fluidity of liquid metal, which can overcome the undesirable phenomena such as sand rising and box lifting during the pouring process; the flat rectangular runner can not only realize effective heat dissipation, but also reduce the heat loss of molten metal along the filling process, so as to ensure the smooth filling of liquid metal in the mold cavity.
The design of runner in gating system should fully consider the structure of cylinder body iron castings and evenly distribute in all parts of the casting. The relationship between the thickness (unit: mm) and quantity of runner and the mass (unit: kg) of cast iron.
The thickness of ingate is related to the wall thickness of adjacent cast iron castings, which is generally 0.5-0.8 times of the adjacent wall thickness, and the width is 3-6 times of the thickness. The width thickness ratio of the thick wall part is small, and the width thickness ratio of the thin wall part is large. The length of ingate is closely related to the quality of castings. Generally, the length of ingate in small castings is 10 ~ 20 mm, that of medium castings is 20 ~ 40 mm, that of large castings is 30 ~ 60 mm, and the distance between them is 20 ~ 30 mm.
In the process of changing the gate area from a single gate to a single gate, only the gate area can be changed from a single gate to a steady one.