Power lithium battery aluminum shell packaging process -Lithium - Ion Battery Equipment
The aluminum shell of the automotive power lithium battery is made of aluminum 3003, because this material is easy to process and form, high temperature corrosion resistance, good heat transfer and electrical conductivity. The power lithium battery aluminum shell (except the shell cover) of 3003 aluminum alloy can be drawn and formed at one time, and the welding process of the bottom of the box can be omitted for the stainless steel shell.
3003 is mainly aluminum-manganese alloy, and the important alloying element is manganese. The boiling point temperature of aluminum and manganese is not much different, and there will be no problems such as the deterioration of weld quality due to the burning of metal elements during welding.
The 3003 aluminum alloy material has the advantages of low density and soft material, and has the advantages of easy overall drawing and forming of the aluminum shell of the power lithium battery. It has been used by many companies for battery packaging. Aluminum alloys are much less dense than traditional stainless steel encapsulation materials.
In order to increase the cruising range, new energy electric vehicles require a large number of lithium-ion battery combination modules, each of which is composed of several battery boxes. In this way, the mass of each battery box has a great impact on the quality of the entire battery module. In order to reduce the quality of the battery, it is an inevitable choice to use 3003 aluminum alloy material to make the battery case.
1) Mold structure and process optimization technology
Due to the characteristics of high temperature and high pressure in die casting of aluminum alloys, the filling form of molten metal during die casting is closely related to quality factors such as casting density, porosity, and surface roughness. And the filling process is carried out in a closed cavity, which is difficult to visualize. It is difficult to obtain process data such as whether the filling process can be carried out smoothly, whether the pouring and discharging system is reasonable, and whether the die-casting process is covered with air. Based on the actual die-casting process, after obtaining the thermal and physical properties of the material, the finite element method is used to establish a die-casting model to analyze the flow field, temperature field and alloy solidification of the die-casting part, study its filling law, and optimize the casting system. According to the calculation results, defects such as pores, cold insulation and shrinkage holes of die castings should be predicted.(Lithium - Ion Battery Equipment)
In addition, the finite element method can also dynamically display the filling process of the mold and the change of the mold temperature field. Using the temperature field simulation results, the temperature field change curve of the important nodes on the surface of the mold cavity is extracted, the node temperature is analyzed, the thermal stress of the node is calculated, the thermal shock of the mold is judged, and finally the thermal crack on the surface of the die-casting mold cavity is judged. .
Therefore, it is necessary to use finite element software to simulate and optimize the die-casting process of the transmission housing for new energy vehicles, and to determine the best opening gate and final forming part of the transmission housing die-casting mold with internal gear structure. A large exhaust is set up at the molding place to solve the problem of cold insulation and air holes. In addition, mold flow analysis is performed on the die casting process to determine liquid metal flow, solidification, and thermal stress in the mold.
2) Temperature control technology
The temperature control of the die-casting process of the aluminum alloy transmission housing for new energy is mainly about the control of the casting temperature and the mold temperature. During the die-casting process of aluminum alloy transmission casing, temperature control has an important influence on the thermal state and processing efficiency of the filling process, and is an important factor for obtaining high-quality castings. Generally speaking, the casting temperature should not be too high or too low. If the casting temperature is too high, the liquid alloy is prone to turbulent flow, eddy current, and vadose in high-speed applications, which will affect the filling quality. However, if the casting temperature is too low, there will be uneven composition and poor fluidity, which will affect the filling conditions and cause defects in the casting.