Research and application of the hottest 3D injecti

Research and application of three-dimensional injection molding simulation system

I. Development Overview and application background

the plastic industry has developed very rapidly in the past 20 years. As early as seven years ago, the annual output of plastic by volume has exceeded the total annual output of steel and non-ferrous metals. Plastic products have been widely used in national pillar industries such as automobile, electromechanical, instrumentation, aerospace and other fields related to people's daily life. Although there are many methods of forming plastic products, the main method is injection molding. About half of the world's plastic forming mold production is injection molding

with the improvement of the complexity and accuracy requirements of plastic products and the shortening of the production cycle, the traditional mold design methods that mainly rely on experience can no longer meet the requirements of the market. In terms of large-scale complex and small-scale precision injection molds, China also needs to increase the production capacity of acrylic resin for optical materials and import molds

II. Key technologies and practical functions

1. Replace the central layer model with a three-dimensional solid model

the central layer model of products based on the traditional injection molding simulation software. Users should first abstract thin-walled plastic products into approximate planes and surfaces, which are called central layers. Generate two-dimensional plane triangular lattices on these central layers, use these two-dimensional plane triangular lattices for finite element calculation, and display the final analysis results on the middle plane. The injection molding product model mostly adopts three-dimensional solid model. Because of the inconsistency between the two models, secondary modeling is inevitable. However, because the shapes of injection molding products are complex, diverse and ever-changing, it is very important to extract every part of the experimental machine from the three-dimensional solid. It is a very difficult work to image the central level, and the extraction process is very cumbersome and time-consuming. Therefore, designers are afraid of difficulties in the simulation software, which has become the bottleneck of the promotion and application of injection molding simulation software

hscae 3D mainly accepts STL file format of 3D solid/surface model. Now mainstream cad/cam systems, such as UG, pro/engineer, CATIA and SolidWorks, can output STL format files with high quality. That is to say, with the help of any commercialized cad/cae system, users can generate STL format files of the three-dimensional geometric model of the desired product. HsCAE 3D can automatically convert the STL file into a finite element lattice model, ensure the coordinated flow of the corresponding surface through surface matching and the introduction of new boundary conditions, realize the analysis based on the three-dimensional solid model, and display the three-dimensional analysis results, eliminating the need to abstract the central layer first in the central layer simulation technology, The complex step of regenerating into grids breaks through the bottleneck of the popularization and application of the simulation system, greatly reduces the burden of user modeling, reduces the technical requirements for users, and shortens the training time for users from the past few weeks to a few hours

2. Comprehensive application of finite element, finite difference and volume control methods

injection molded products are thin-walled products, the size of the product in the thickness direction is far smaller than that in the other two directions, and the changes of physical quantities such as temperature in the thickness direction are very large. If a simple finite element or finite difference method is used, the analysis time will be too long, which cannot meet the actual needs of mold design and manufacturing. We use the finite element method in the flow plane and the finite difference method in the thickness direction to establish the grids that are suitable for the size of the flow plane and the thickness direction respectively and solve them by coupling. On the premise of ensuring the calculation accuracy, the calculation speed meets the needs of the project, and the control volume method is used to solve the moving boundary problem in forming. For products with different internal and external corresponding surfaces, they can be divided into two parts of volume, and their respective control equations are formed. The coordination of these two parts is ensured by interpolation and comparison at the junction

3. The combination of numerical calculation and artificial intelligence technology

optimization of injection molding process parameters has always been the concern of mold designers. Although the traditional CAE software can simulate the injection molding situation under the specified process conditions on the computer, it cannot automatically optimize the process parameters. The users of CAE software must set different process conditions for many times of CAE analysis, and combine actual experience to compare among various schemes, so as to obtain a more satisfactory process scheme. At the same time, after CAE analysis of parts, the system will produce a lot of information about the scheme (products, process conditions, analysis results, etc.), in which the analysis results often appear in the form of various data fields, requiring users to have the ability to analyze and understand CAE analysis results. Therefore, traditional CAE software is a passive calculation tool, which cannot provide users with intuitive and effective engineering conclusions, The requirements for software users are too high, which affects the application and popularization of CAE system in a wider range

in view of the above shortcomings, based on the accurate calculation function of the original CAE system, HsCAE 3D software introduces knowledge engineering technology into the development of the system, uses the thinking and reasoning ability of artificial intelligence to complete the analysis and processing of a large amount of information instead of users, directly provides guiding process conclusions and suggestions, and effectively solves the unique problem of Beijing Carlyle Yizhong (Qingdao) and a few other enterprises produce one component polyurethane waterproof coatings; However, in recent years, the contradiction between complexity and the simplicity of user requirements has shortened the distance between CAE system and users, and promoted the simulation software from the traditional "passive" computing tool to the "active" optimization system. HsCAE 3D system mainly applies AI technology to the initial process scheme design, the interpretation and evaluation of CAE analysis results, and the improvement and optimization of analysis scheme

the main optimization methods used in knowledge-based simulation system:

(1) optimization based on case-based reasoning. It is mainly applied to the initial design of forming process with discrete value space. The shape of the product and the structure of the gating system are coded, while the size information is described by characteristic parameters. Based on the collection and abstraction of previous successful process design, the index and retrieval mechanism of case base described in the form of framework is established

(2) optimization based on artificial neural network. The parameters with continuous value space such as injection time and injection temperature in process design are optimized by the method based on artificial neural network. Using the optimization objective function and under a certain optimization strategy, the optimal parameters confirmed by the optimization system are obtained

(3) optimization based on rule reasoning. It is mainly used for the interpretation and evaluation of the analysis results. The expert system rule base established by this system is based on the expert knowledge in the field of injection molding, covering the knowledge of short shot, flow balance, melt degradation, temperature difference control, pressure holding time, allowable shear stress, shear rate, mold locking force, etc. on the basis of analyzing and refining the calculation results, it drives the expert system to reason and analyze and evaluate the forming scheme, Specific optimization and improvement suggestions are given

4. Integrated analysis of three-dimensional flow and pressure maintaining of products and runner system

runner system generally adopts cylindrical elements, while products adopt triangular elements. HsCAE 3D system adopts semi analytical method to solve the problem of integration and solution of mixed elements. In this way, HsCAE 3D system can not only analyze several engineers of the first mock examination Hexion, but also stay in the factory for large and complex products, Moreover, it can analyze small precision products with the first mock examination and multiple cavities, which greatly broadens the application range of the system. At present, HsCAE 3D system is the world's advanced three-dimensional simulation software that can analyze the the first mock examination multi cavity flow balance problem

5. An efficient algorithm for predicting fusion lines of plastic products

fusion lines have an important impact on the strength and appearance of products. Accurately predicting the location of fusion lines is a difficult problem for simulation software. HsCAE 3D system greatly improves the accuracy and efficiency of fusion pattern prediction through the node feature model method, and its accuracy has reached the advanced level of similar international products. The neural network method is used to make a qualitative evaluation of the influence of fusion lines, which provides a direct basis for users to evaluate the forming quality