Gating system designs of a pedestal frame for pumps basedon numerical simulation and experimental study

• Main Authors: Zhong, Qi, 鍾齊
• Other Authors: Huang, Pei-Hsing
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/hgsv6k

碩士 === 國立屏東科技大學 === 機械工程系所 === 105 === Investment casting technology shown increasing maturity and stability in recent years. The products present high precision and excellent mechanical properties, and as a result, investment casting is widely applied to the mass production of metal components with complex structures. This study examined the fixed base of a water pump. The long-term operations of pump motors create various vibrations that can lead to resonance and fatigue failure in the structure, which shortens product lifespan and reduces overall system efficiency. This study employed computer-aided moldflow analysis technology based on finite-difference methods (FDM) to remedy the macroscopic shrinkage cavities, microscopic porosity, and porosity defects that are common in investment casting and optimize the design of the gating system for an SUS304 stainless steel pump base product. To shorten the development process of the product and reduce development costs, we incorporated moldflow analysis into the initial casting scheme and experiment verification to observe the filling and solidification of the molten metal and the distribution of gas pressure. Porosity defection prediction and the assessment of formation probability were performed based on the retained melt modulus and the Niyama criterion. By changing the gate design, adjusting the position and dimensions of the runner and inlets, adding top risers and exhaust ducts, and altering parameters such as casting speed and temperature, we optimized the casting scheme and input the results into the pump base production process. Following the optimization, the flow rate through the gate decreased significantly about 6.6~10 cm/s, which effectively reduced the turbulent flow within the mold cavity. Moreover, the solidification of the molten metal in the fed portion was also delayed by 36.5 sec, which reduced the probability of isolated residual melt and shrinkage defects. According to the non-destructive test results, the optimized casting scheme eliminated the porosity defects in the original scheme and further enhanced the quality and mechanical properties of the product.