Numerical Simulation Method Of Glass Blowing Forming Process

Blowing forming is one of the most versatile and widely used manufacturing processes of glass container, which is characterized by accurate, efficient and stable forming action. However, the mold designs, machine timings, and equipment cooling techniques are still based on the experience and trial in industrial production, which cause long die testing cycle and make it difficult to produce light weight and structuring glass container. Some key phenomena such as the compacting blowing circle defect and uneven thickness distribution are lack of quantitative controlling tools. In the background that low-carbon and green manufacturing are highly concerned in the world, the above problems seriously restrict the transformation, upgrading and energy saving for high energy consuming glass industy, and have become the main development obstacles.It is an inevitable trend to solve the above problems by the numerical simulation method. Quite a few researchers have attempted various approaches in this area. However, the current research on the blowing forming theory and algorithm is not systematic and comprehensive. Because of the strict secrecy system in glass indrusty, it is difficult to direct the production by using numerical simulation technique due to lack of the basic data of practical production. Up to the date, there still is not any specialized commercial CAE software in the world to deal with glass blowing forming.Following the route of numerical simulation, experiment verification and guiding production, the dissertation systematically carries out the theory and algorithm research of blowing forming simulation. The objective is to develop the blowing forming simulation software that can guide production practice. The main results are as follow:1. Based on the features of blowing forming, the flow behavior of glass melt is described by Lagrange method. The governing equations of melt flow and heat transfer of blowing forming process are built using the dimensional analysis method. The viscosity is calculated using the modified Vogel-Fulcher model, and the response of viscosity to shear rate is also considered.2. The finite element formulas about velocity and pressure are derived by means of Galerkin method. The solving area is divided into rectangular and triangular elements. To increase computing efficiency, different remeshing strategy is used in order to minimize the impact of remeshing.3. There is a rapid and drastic heat exchange between the melt and mold during the blowing forming, so a coupling simulation of melt and mold heat transfer is crucial. The solving formulas are constructured by means of developing the interface element to deal with heat transfer between glass and mold. To rapidly reconstruct temperature field, a special technique is employed in which the melt area is divided into the fan-shaped region. The coefficients of heat transfer between the mold and glass melt and the mold and air are obtained by the comprehensive utilization of experiment and numerical calculation. The predicted mold temperature is consistent with that of experiment measure.4. Based on the above theory and algorithm, the blowing forming simulation software GlassCAE is developed with Visual C++. The simulation results show that the temperature in most parts of mold keeps stable during the continuous production except the area close to the melt-contact surfaces where the temperature has high periodic changes. By using the numerical simulation, it is easily found that there is the huge variation of the parison temperature near the compacting blowing circle which stems from the different contact time of glass melt and mold. This is the inherent defect of blowing forming. The simulation also reveals the key reason of the defects.5. The dissertation carries out the thickness simulation verification by measuring thickness of green, brown and white material product. The average accuracy is respectively84.52%,83.95%and85.48%. The verification result shows that the research work on theoretical model construction, algorithm and software development is reasonable, feasible and reliable, and has important guiding significance for real production. 6. Using GlassCAE, the light weight and structuring problem of the normal weight glass container is studied. Through the simulation optimization, the thickness of glass container is more uniform, and achieves light weight standard. The light weight index drops from1.52to1.34. The structure performance test proves that the light weight product meets the mandatory requirement of GB4544-1996. It proves that the simulation software has important significance for guiding light weight and structuring design.The dissertation systematically constructs the governing equations of melt flow and heat transfer of blowing forming process, which develops the theory of glass forming. The simulation software GlassCAE has been verified by comparison with the real practice, and has important application value.