Research on virtual design technology of the hotte

Research on virtual design technology of packaging machinery China is a large country of packaging machinery, but there is still a big gap between the level of packaging machinery in China and the advanced level in foreign countries. To improve the technical level of packaging machinery in China, it is necessary to adopt advanced methods in product design, development and manufacturing. The rapid development of computer and network technology has provided a strong support for the realization of this goal. Many new concepts and ideas have emerged, and virtual design is one of them. Virtual design technology is based on computer simulation and product life cycle modeling. It integrates many technologies such as computer graphics, artificial intelligence, concurrent engineering, network technology, multimedia technology and virtual reality technology to conceive, design, manufacture, test and analyze products under virtual conditions. Its remarkable feature is to use the digital model - virtual product to replace the physical model for simulation analysis, so as to provide the decision-making level of the product in the multi-objective of time, quality, cost, service and environment, and achieve the goal of global optimization and one-time development [1]. User oriented product virtual design is an effective means to meet the diversified needs of products, which has been studied by scholars at home and abroad. For example, j.bernhard et al. Studied and implemented a virtual design service system based on Java3D technology [2]; Zhou Jun of Shandong University studied the design principle, basic features, architecture, design content and design process of the virtual design of the production line in detail, and combined with application examples, established the virtual model of the production line, visually simulated its running state, quickly diagnosed its bottleneck process, and effectively integrated the design, simulation, analysis, diagnosis, optimization, reorganization and other functions of the production line [3]; Gao Guangda of Tianjin University studied the macro planning, module creation design and interface design of modular virtual design system, as well as the rapid virtual creation technology and scheme evaluation technology of modular products, and developed the virtual modular design platform for CNC machine tools [4]. The virtual design technology is applied to the field of packaging machinery design to realize product design, manufacturing, prediction of product performance and machinability on the computer, so that the design, development and manufacturing technology of packaging machinery has developed from the traditional method to a new stage, enabling enterprises to make rapid and agile response to changes in market demand, and make reasonable adjustment and re planning for their own production in time, With the most economical cost and the shortest development cycle, develop suitable packaging machinery systems or products

1 development environment of packaging machinery virtual design the realization of packaging machinery virtual design needs a reasonable product development environment. It enables design, evaluation and product change to be carried out in parallel in the development team, and builds a bridge at different stages of product development by sharing virtual prototypes in the product database. The environment can be built with existing CAD, CAE, cam tools, engineering knowledge base and model base. The conceptual prototype of the product can be generated virtually by computer means. The virtual product can be evaluated by interactive simulation, and its key manufacturing processes and costs can be simulated and optimized. In concurrent engineering, product data flows dynamically in each design unit. Without a product data management system (all statistical data can also be remotely controlled through an app program installed on a mobile phone), multiple backups of geometric models, calculation results, input data and analysis data will be generated, and outdated data may be used, which will waste time and cost. Therefore, the virtual product development environment should have a PDM subsystem, as well as two subsystems: virtual design and simulation analysis. PDM subsystem is the core of virtual product development, which mainly manages 3D CAD model data and product development process; The virtual design subsystem can realize the definition and solution of design problems, and feed back the information generated in the prototyping, simulation and evaluation stages to the designer to assist the design decision-making; The simulation analysis subsystem directly generates design decisions by defining appropriate product, process and activity models, integrating prototype and manufacturing activities, and can simulate the entire assembly process. Moreover, the running time and cost of the machine can also be calculated using the enterprise's standards [5]. Figure 1 shows the development environment for virtual design of packaging machinery. In the process of product development, after the design concept is determined, the basic design model is represented as a three-dimensional solid model, that is, a virtual prototype, which can be realized by CAD software. The model and related information are stored in the PDM system. Using solid models, we can create analysis models, such as process models and activity models, to realize process design, assembly simulation and virtual testing, as well as structural, kinematic and dynamic analysis

2 modeling process of virtual design of packaging machinery establishing the three-dimensional model of packaging machinery is the largest part of the system. In order to maintain the correct geometric dimensions and constraints of all parts when the overall parameters change, the three-dimensional parameterization technology must be adopted. Pro/e parametric cad/cam design software is a widely used three-dimensional modeling tool at present. It is widely used in mechanical design, mold design, manufacturing and mechanism analysis in mechanical, automotive, home appliance and other industrial fields. It has the functions of part design, engineering drawing, product assembly and so on. The design modules of pro/e are all related. Any modification in the design process can be extended to the whole design, and all engineering documents, assembly and design drawings, manufacturing data, etc. can be automatically updated. Therefore, pro/e can be used as the main support software to establish the case library of all parts of the packaging machinery, and establish the parameter relationship according to the geometric shape of the parts and the constraints of the mutual relationship, so that the correct relative position and assembly relationship between the parts of the packaging machinery can always be maintained in the design process. In order to enable ordinary technicians to use pro/e, a powerful cad/cam design software, 352pro/toolkit technology can be used to call the functional modules of pro/e, realize the integration of application program and pro/e, and form a specific architecture and design menu for packaging machinery design, so that technicians can quickly master the use of the software. The basic parameter input, finite element analysis and three-dimensional parametric design modules of the packaging machinery are integrated into the pro/e operating environment. The design user can modify the parameters and dimensions of any structure of the packaging machinery at any time, and call the finite element analysis module to check the strength and stiffness. In addition to calling the pro/e application program, the design process, data input and output functions are implemented by VC programming

3 product prototype in the virtual development environment in order to check the assembly of parts in the virtual environment, find out the design errors in time and improve the design efficiency, we do not manufacture the real prototype, but use the virtual prototype technology to construct the virtual product prototype. Virtual prototype technology is a fully digital design method based on computer simulation model of products. Virtual prototype environment can combine the development models in different engineering fields, so that designers can carry out effective and verifiable design work before the physical prototype is produced, and improve the mutual communication in product development projects. Virtual prototyping enables developers to communicate with customers about products in a natural way as early as possible to meet customer requirements

the virtual prototype builds a visual digital model on the computer just like the real prototype. The virtual prototype adopts the "reference" method. It does not really send all the unconfirmed components to the assembly model, but only memorizes the position of the components in the model and loads the components when necessary, so as to greatly save the hard disk and memory space. Moreover, when the surface accuracy of the line material printed parts becomes poor, the assembly model will be automatically updated after the components are modified, which saves a lot of work. In addition, the components referenced by the assembly model can be stored in the computer of each user, the central server or anywhere connected through the network, which provides a technical basis for the development of concurrent engineering and makes it possible for the team to work together. There are two types of virtual assembly, top-down and bottom-up [6]. For machines with complex product structure and shape, the size and shape of internal parts largely depend on the product shape, and the top-down type can be adopted. In the environment of virtual assembly, the shape of the whole machine is designed first. After the shape is determined, the "control component" output is distributed to the relevant parts, and then the parts are designed in detail. For the design process from the detailed design of each component to the final assembly of components, the bottom-up method can be adopted. Fitting, alignment and orientation can be used to constrain the matched parts during component assembly. Even if a part is modified, this constraint relationship still exists. This assembly mode is applicable to products with complex transmission mechanism, compact structure, many changes in form, easy interference between parts, and high requirements for action reliability and accuracy

4 conclusion virtual design replaces the physical prototype with the product model. Through the product evaluation of the model simulation test, it can obtain higher design quality at a lower cost, and greatly improve the flexibility and agility in the process of new product development. The application of virtual design technology to packaging machinery design will help to improve the design ability of packaging machinery products and promote the development of packaging machinery industry in China

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