As a material processing technology that has been used for thousands of years, sand casting is the most direct way from liquid metal to product molding. At the same time, this most direct material molding technology also contains great difficulties. Because in this manufacturing process, multiple links need to be controlled at the same time, including metal melting, alloying, mold design and manufacturing, modeling, liquid metal filling and solidification, post-processing and so on. In order to obtain high-quality sand castings, each link must be accurately controlled. Any problem in any link may lead to the scrapping of sand castings. Through examples, CAD, CAE and CAM technologies are penetrated into the sand mold casting process design to realize the overall control of sand mold casting process design as far as possible. The theoretical design of sand casting process, three-dimensional modeling design of tooling, computer simulation of mold filling and solidification process, analysis of simulation results and process optimization, template design and NC machining of template are completed. In addition, the finite element analysis of parts is introduced into the sand casting process design, and their own views and conclusions are interspersed in many links. Finally, a set of ideas and methods of comprehensively using CAD, CAE and CAM technology to assist the sand casting process design are fully displayed.
The main conclusions are as follows:
(1) By studying the influence of specific process measures on the local quality of finished sand casting, the necessity of introducing part mechanical analysis into sand casting process design is expounded. In order to meet the requirements of producing high-quality sand castings, the finite element analysis of the parts before the sand casting process design is helpful to clarify the actual situation of the performance requirements of the parts for each part, and plays a guiding role in the selection and use of specific process measures.
(2) Using the modeling module of UG NX and combined with the theoretical knowledge and experience of sand mold casting process design, the three-dimensional modeling of the gating and riser system is completed. According to each process optimization, the gating and riser system is adjusted and improved accordingly, and finally the tooling manufacturing model of the gating and riser system is determined. Based on the advantages of UG NX full parametric design, on the premise of repeatedly adjusting the process, compared with the traditional drawing method, the drawing efficiency can be greatly improved.
(3) Sand casting CAE technology can enable sand casting engineers to more intuitively understand the changes of temperature field, velocity field and pressure field in the mold cavity during liquid metal filling and solidification. It is the best “experiment” to determine the sand casting process when the parameters are set reasonably. In this paper, AnyCasting software is used to repeatedly simulate the filling and solidification process of liquid metal, so as to ensure that the modification and optimization of sand casting process are reasonable.
(4) Using the principle of sand mold casting flexibly, combined with the analysis of the CAE simulation results of sand mold casting, the reasons and effects of each modification and optimization of sand mold casting process are described in detail, and the sand mold casting process is finally determined. This method is very beneficial to improve the success rate of one-time trial production of sand mold casting process.
(5) According to the determined sand casting process, the three-dimensional design of the formwork is carried out by using the modeling module of UG NX. The NC machining process of the template is designed and simulated, and finally the NC code is generated, which realizes the overall control of sand mold casting process design and mold machining design.
Innovations include the following:
(1) The mechanical analysis of parts is introduced into the process design of sand casting. Through the finite element analysis of parts, the weak area of sand casting is intuitively displayed. The subsequent process design is applied on the premise of ensuring the liquid metal forming quality in this area, which is of great significance for the output of high-quality sand casting.
(2) Through examples, with the help of large-scale general CAD / CAE / CAM integrated software UG NX and sand casting CAE software AnyCasting, a set of new ideas of applying CAD, CAE and CAM technology to assist the research and development of sand casting process are fully and in detail demonstrated.