The average wall thickness of the heat dissipation fins on the radiator in the automotive steering system is relatively thick, and there are many thin-walled and slender structures, which require high dimensional accuracy and overall quality. The heat dissipation effect of sand casting heat sinks is poor, the production method is outdated, the cycle is long, the cost is high, and the efficiency is low, making it difficult to meet the increasingly expanding market demand and technological updates of heat sinks. Aluminum alloy has excellent thermal conductivity, and die-casting parts have the characteristics of dense organization, high surface quality, and high dimensional accuracy. Die cast aluminum alloy heat sinks have broad application prospects. Computer simulation software can simulate the occurrence of gas inclusions and temperature fields during the die-casting process, predict the possible locations of defects in the entire mold cavity, and improve the process more accurately and efficiently, reducing production costs and increasing efficiency. This project designs the die-casting process for aluminum alloy heat sinks, using Flow-3D software for simulation analysis. By adding overflow grooves and improving the size of the sprue, the process is optimized to obtain a reasonable die-casting process plan. And further validate the rationality of the die-casting process through trial production.
Based on the structure of the heat sink, design the die-casting process scheme for aluminum alloy heat sink, and then use Flow-3D software to numerically simulate the die-casting process scheme. The simulation results show that there are air entrapment defects at the four corners of the lower part of the heat sink. Trial production was carried out on the process plan, and the produced samples were subjected to non-destructive testing and sectioning observation. It was found that the results were consistent with the simulation, with a large number of pores and pinholes appearing at the corners.
Graphic and textual results
The external dimensions of the heat sink are 99mm × 89mm × 41.7mm, with a mass of approximately 375g. The maximum wall thickness is 33mm and the minimum wall thickness is 2.5mm, making it a small to medium-sized casting. The main body of the heat sink is a rectangular prism with a thickness of 13mm. There is a 20mm high protrusion in the middle of the heat sink, which is the thicker part of the casting; At each of the four corners of the casting, there is a 28mm long extension leg, and on the side of the extension leg, there are inclined ribs with a thickness of 2.5mm and a height of 26mm, which are the thin-walled areas of the casting. The aluminum alloy is made of ADC12 aluminum alloy. DM180 horizontal cold chamber die-casting machine is selected and produced in the way of the first mock examination and two pieces. See Figure 1 for the three-dimensional structure of aluminum alloy radiator.
Firstly, set the die-casting process parameters in Flow-3D software, with a pouring temperature of 680 ℃, a mold preheating temperature of 200 ℃, and a filling speed of 20m/s. Convert the initial 3D solid model of the process design into STL format and import it into Flow-3D software for mesh generation.
y analyzing the structure of the heat sink, a reasonable die-casting process was designed, and the initial process was numerically simulated to predict the location and severity of defects and analyze the causes of defects. By adjusting the size of the sprue for process optimization, the simulation results showed that the defects were effectively eliminated. Trial production was conducted on the optimized plan, and the produced samples were subjected to non-destructive testing and sectioning observation. The results showed that pores and pinholes were effectively eliminated, meeting the requirements for use while reducing the scrap rate. By improving the size of the sprue and other measures to optimize the process, and verifying the improved process, the defects that occurred in the initial process were basically solved.
Author of this article:
Song Zhengcong 1 meter national development 1 Zhou Zhijie 2 Li Changyun 1 Xu Lei 1
1. School of Materials Science and Engineering, Henan University of Technology; 2. Henan Pingyuan Optoelectronic Technology Co., Ltd
This article is reprinted from the magazine "Special Casting and Nonferrous Alloys"
