CAD integration technology of the hottest plastic

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Plastic mold CAD integration technology

0. Introduction

mold CAD integration technology is an important advanced mold manufacturing technology, and an important key technology to transform the traditional mold technology with high technology. Since the sixth five year plan, many mold enterprises in China have adopted CAD technology. Especially in recent years, the application of CAD technology has become more and more common and in-depth, which has greatly shortened the mold design cycle, improved the mold quality and the manufacturing capacity of complex molds. However, many enterprises have insufficient understanding of mold CAD integration technology, and the investment is blind, which can not play a good role, resulting in a lot of waste. This paper presents some views on the integrated technology of plastic mold CAD and its application for your reference

1. Plastic mold CAD integration technology

plastic mold manufacturing, including plastic product modeling design, mold structure design and analysis, mold numerical control processing (milling, electrical processing, wire cutting, etc.), polishing and test mold, rapid prototyping manufacturing, etc. CAD cell technologies involved in each link include: Modeling and structural design (CAD), rapid reverse engineering of product shape (RE), structural analysis and optimization design (CAE), auxiliary manufacturing (CAM), virtual simulation of machining process (simulation), rapid prototyping of products and molds (RP), auxiliary process planning (CAPP) and product data management technology (PDM), etc. Plastic mold CAD integration technology is to integrate various unit technologies involved in the plastic mold manufacturing process, unify the database and file transmission format, and realize information integration and data resource sharing, so as to greatly shorten the mold design and manufacturing cycle and improve the mold quality

2. CAD design of plastic products and rapid reverse of shape

the first step in plastic mold design and manufacturing is the design of plastic products. The traditional product design method is that the designer expresses the three-dimensional idea of the product with two-dimensional plane drawings, and the drawings indicate the process and construction method. This method determines the simplicity of the designed graphics and cannot directly control the manufacturing quality. The modern design method is that the designer directly establishes the three-dimensional model of the product on the computer, carries out the mold structure design and optimization design according to the three-dimensional model of the product, and then carries out the processing programming and process planning according to the three-dimensional model of the mold structure design. This method makes the product model design, mold structure design, processing programming and process design based on 3D data, and realizes data sharing, which can not only quickly improve the design efficiency, but also ensure the quality and reduce the cost

there are three sources of computer plastic product models: product model design using CAD system software, rapid reverse modeling using physical measurement, and standard format files using other CAD systems. Aiming at the source of these three product models, various technologies have been developed to improve the design efficiency and quality of product models. The connotation and characteristics of various technologies are further analyzed below

using CAD system software for product model design, its technology mainly includes the drawing of two-dimensional geometric graphics, the design of two-dimensional parametric graphics, three-dimensional solid modeling design, three-dimensional feature modeling design, three-dimensional parametric solid modeling design, three-dimensional surface modeling design, space free modeling design, product appearance rendering, product dynamic advertising design, etc. These software have many typical representatives. Two dimensional software: ME10, cadkey, AutoCAD, dhcad, etc; 3D software: NX, pro/e, CATIA, etc; The software of product free modeling and advertising design includes alias, CDRs, etc. The drawing of two-dimensional geometry is to use plane CAD software to draw part graphics, that is, to use computer instead of manual drawing; The two-dimensional parameterization, that is, the computer realizes the variable design of graphics, which makes the modification more convenient; 3D modeling design is the real shape design of digital products. It completely expresses the products and can further provide the necessary mathematical model for mold design, analysis and processing; Space free modeling design is the artistic design of product shape, so that the product is not only a functional product, but also a work of art; The appearance rendering of the product is the effect design of the product, which makes the product more beautiful and the color more able to meet people's various needs; The dynamic advertising design of products is to directly make advertising and market promotion based on the results of product design

using physical measurement for rapid reverse modeling is one of the hotspots of current research. It is an important technology for product modification design based on product imitation, which leads to large errors in the finally detected data. Its basic principle is to scan and measure the real object through a three coordinate measuring machine, a laser measuring machine or an electronic reading meter, and send a large number of digitized data points obtained from the measurement into the reverse module of advanced CAD software or a special reverse software. The reverse software can directly read the point data group, and can carry out, filter, sort, refine, sort and locally modify the point data group. The order of extruder enterprises will be greatly recovered and reorganized, Then the surface is automatically generated, and finally the product model of computer plastic parts that is accurate and consistent with the real object or has been transformed is obtained. This method can greatly improve the design speed of new products. At present, the more mature surface reverse modeling software includes surfacer, cimatronrenge, strim100, etc

it is convenient to use the standard format files of other CAD systems to model. Due to the globalization of the market and the development of Internet technology, many CAD technology exchanges and cooperation among mold enterprises are carried out through CAD files. Because there are many kinds of CAD systems, the format of files must comply with international standards, such as DXF, IGES, step, VDA, STL, etc. By reading the standard format file to directly establish or modify the product model, we can not only speed up and deepen the communication between users and mold manufacturers, but also shorten the product design cycle

3. CAD design and analysis of mold

CAD design and analysis of mold, including the design of mold parting surface according to product model, the determination of cavity and core, the detailed design of mold structure, the analysis of plastic filling process and so on. Using advanced feature modeling software such as pro/e and UGII, it is easy to determine the parting surface, generate the upper and lower mold cavities and cores, and then arrange the runner, gate and cooling water pipe. After these design data are determined, mold analysis software such as Moldflow and cflow are used to analyze the plastic forming process. According to moldfolw software and its rich material and process database, by inputting the forming process parameters, it can dynamically simulate and analyze the flow of plastic in the injection mold cavity (including the analysis of plastic manifold flow pattern during multi gate injection), analyze the temperature and pressure changes, analyze the residual stress of injection parts, etc., and check the rationality of mold structure, flow state, product quality problems, etc. according to the analysis. For example, whether the gating system is unreasonable, the location and size of runner and gate are improper, and the mold cavity cannot be balanced and filled; Whether the product structure is unreasonable or the mold structure is unreasonable, and the product is not full (i.e. short shot); Whether the cooling is uneven, which affects the production efficiency and product quality; Whether there is wrong injection molding process, warpage and deformation of products, etc. Through CAD design and analysis, errors can be eliminated in the design stage and the success rate of one-time mold trial can be improved

many new computer-aided technologies have been applied in the stage of plastic mold design and analysis, such as parameterization technology, feature modeling technology, database technology, etc. There are many standard parts in plastic mold, such as standard mold base, ejector mechanism, gating system, cooling system, etc., which can be designed by using the parametric feature modeling design method based on database management or establish a standard part library, which can not only realize data sharing, but also meet the user's modification of the design at any time, so that the design and analysis of the mold is fast, accurate and efficient. Parametric feature modeling can not only completely describe the geometric information of products, but also obtain the accuracy, material and assembly information of products. The product model established by it is easy to deal with and can reflect the design intent and processing characteristics. Therefore, parametric feature modeling technology is one of the most important technologies in mold manufacturing process

4. Application of CAM technology, machining simulation and manufacturing of molds

Computer Aided Manufacturing (CAM) technology of molds is mainly used in NC milling, wire cutting, EDM, etc. CAM technology plays a more important role in milling the cavity, core and electrode of complex dies. Its main technical features include: (1) the optimal planning of rough and finish machining tool paths and the generation of NC instructions, (2) the establishment of tool types, characteristics and material libraries, (3) the determination of cutting process parameters, (4) the characteristic control of ordinary cutting and high-speed cutting, (5) over cutting inspection and precision control of machined surfaces, (6) computer solid simulation cutting in the machining process, (7) The application of DNC technology and group control technology of computer-controlled CNC machine tools, etc

CAD 3D product model data is particularly needed in the application of CAM technology. Many professional computer programming software such as Mastercam, unimod, Cimatron, etc. have high requirements for the surface model of products during the programming and processing of multiple surfaces, such as the consistency of u and V directions of adjacent surfaces, high-precision fitting between surfaces, continuous change of surface slope, etc. In advanced cad/cam integrated systems (such as UGII, pro/e), due to the use of parametric feature modeling design and the same database technology, there is an internal relationship between product model data, mold cavity and core model data, tool path data, and the tool path of product model modification is also automatically modified

the solid simulation technology of mold processing is becoming more and more mature, and people pay more and more attention to it. Machining entity simulation is to simulate the machining process of machine tools on the computer, which can directly reflect the machining results, directly evaluate the quality of machined parts, and check out machining errors. When checking the quality of machined parts, the machined solid model can be cut arbitrarily on the computer, and its size and accuracy can be measured directly. Therefore, it can eliminate errors in the programming stage of processing technology, reduce the repair and rework after processing, and greatly improve the manufacturing efficiency and quality of molds

5. Rapid prototyping and manufacturing of plastic products and their molds

plastic products and their molds can be manufactured by rapid prototyping technology after they are designed by computer CAD technology. This is a new concept of manufacturing technology, which abandons the traditional machining methods. Its forming principle is to discretize the three-dimensional CAD solid model into a series of slice data with a set thickness, read these data by laser forming machine or other forming equipment, and stack each layer in turn to form with material addition technology. This technology is called rapid prototype. It loads the load sensor on the actuator to ensure the accuracy of the loading force value; The spindle mechanism is driven by the control Electromechanical, and the ball screw runs along the x-axis. The displacement is controlled by the high-precision displacement measurement mechanism, which is also an important part of CAD integration technology

the first rapid prototyping equipment was born in American 3D company in 1987. Because its characteristic is independent of the complexity of the products manufactured, it has brought great shock to the manufacturing industry. In the following ten years, rapid prototyping technology has developed rapidly, and the types of equipment are also emerging in endlessly, from the aspect of material curing

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