In the production of plastic cast aluminum parts, the thermal balance design of plastic molds is crucial. The mold temperature directly affects the fluidity of the aluminum liquid, the solidification speed and the quality of the final casting. If the mold temperature is uneven or unstable, it may lead to insufficient filling of the aluminum liquid, resulting in defects such as pores and shrinkage holes, and will also affect the dimensional accuracy and surface quality of the casting. For example, local overheating of the mold will cause the aluminum liquid to solidify too quickly, hindering the subsequent inflow of aluminum liquid and causing internal defects in the casting.
Selecting the right mold material is the basis of thermal balance design. The mold material should have good thermal conductivity so that heat can be transferred quickly and evenly. At the same time, it must have a high specific heat capacity, be able to absorb heat when the aluminum liquid is injected without excessive heating, and effectively release heat during the cooling stage. For example, some high-performance mold steels can optimize thermal performance while ensuring strength after special treatment, meeting the thermal balance requirements of plastic cast aluminum parts production.
The cooling system is the key link in achieving mold thermal balance. Reasonable cooling water channel layout can effectively take away the heat of the mold. The water channel should be as close to the cavity surface as possible, but it should not affect the structural strength of the mold. A variety of water channel designs such as spiral and circular shapes are used to ensure uniform heat dissipation. For example, independent cooling water channels are set around the core and cavity of the mold, and the diameter, spacing and water flow rate of the water channels are adjusted according to the heat distribution to achieve precise temperature control.
In addition to the cooling system, a heating system is also required in some cases to maintain the thermal balance of the mold. In the early stage of production or intermittent production, the heating system can quickly heat the mold to a suitable working temperature. By embedding heating rods, heating plates or using hot oil circulation heating inside the mold, the temperature of the mold can be flexibly adjusted to compensate for the heat loss caused by changes in ambient temperature or repeated injection of aluminum liquid.
In order to grasp the temperature changes of the mold in real time, it is essential to install temperature sensors at key parts of the mold. These sensors feed back temperature data to the control system, and the control system automatically adjusts the operating parameters of the cooling system and heating system according to the preset temperature range. For example, when the temperature in a certain area of the mold is too high, the cooling water volume is increased or the water flow rate is accelerated; when the temperature is too low, the heating system is started for compensation, thereby ensuring that the mold is always in a stable thermal balance state.
With the help of computer simulation technology, thermal balance is simulated, analyzed and optimized during the mold design stage. By simulating the heat transfer during the filling and solidification of aluminum liquid, the uneven temperature distribution problem that may occur in the mold is predicted, and the design of the cooling system and heating system is adjusted. In this way, potential thermal balance problems can be discovered and solved before actual production, improving production efficiency and product quality, and reducing the number of mold trials and costs.
The molding process parameters of plastic cast aluminum parts, such as the pouring temperature and pouring speed of aluminum liquid, are interrelated with the thermal balance of the mold. During the production process, these process parameters and the thermal balance design of the mold need to be adjusted in coordination. For example, when the pouring temperature of aluminum liquid is increased, the cooling system parameters of the mold should be optimized accordingly to ensure that the mold temperature is stable, so that the entire molding process is in the best state and high-quality plastic cast aluminum parts are produced.
