In the process of die casting production, where will stress occur?

In the process of die casting production, where will stress occur?

1. Opening: In the process of core pulling and opening, mechanical stress will also occur when some components are deformed.

2. Mould temperature: Mould should be preheated to a certain temperature before production. Otherwise, when high temperature liquid metal fills the mould, chilling will occur, which will increase the temperature gradient of the inner and outer layers of the mould, form thermal stress, and make the surface of the mould crack or even crack. In the process of production, the temperature of the die keeps rising. When the temperature of the die is overheated, it is easy to stick the die. The failure of the moving parts results in the surface damage of the die. The cooling temperature control system should be set up to keep the working temperature of the die within a certain range.

3. Filling: Mold filling with high pressure and high speed will inevitably produce intense impact and scour on the die, resulting in mechanical stress and thermal stress. In the impact process, the metal liquid, impurities and gases will also have complex chemical interaction with the surface of the die, and accelerate the corrosion and crack generation. When the liquid metal is wrapped with gas, it will expand in the low pressure area of the cavity first. When the gas pressure rises, it will produce inward blasting, pull out the metal particles on the surface of the cavity and cause damage, resulting in cracks due to cavitation.

4. Production process: In each die casting production process, due to the heat exchange between the die and liquid metal, periodic temperature changes occur on the surface of the die, resulting in periodic thermal expansion and contraction, and periodic thermal stress. For example, when casting, the die surface is subjected to compressive stress due to temperature rise, and when the die is ejected from the casting, the die surface is subjected to tensile stress due to temperature drop. When the alternating stress is repeated, the accumulated stress in the die becomes larger and larger. When the stress exceeds the fatigue limit of the material, the surface of the die will crack.