Application of the hottest rapid prototyping techn

  • Detail

Abstract: This paper introduces the application and cases of rapid prototyping technology in product design evaluation and audit, product function test, communication with customers and orderers, and rapid tooling. In the rapid development of new products, this technology is one of the key enabling technologies to accelerate the product development cycle and improve the market competitiveness of enterprises

key words: rapid prototyping, product development, manufacturing system

1 preface

in the past 20 years, the manufacturing market environment has undergone great changes: on the one hand, the short timeliness of consumer interest and the increasingly subjective, personalized and diversified consumer demand; On the other hand, the regional and international market barriers have been weakened or broken, which makes manufacturers have to focus on the fierce competition in the global market in order to effectively reduce the collision of profiles in the process of manufacturing and operation. Quickly bringing diversified products to the market is an important guarantee for manufacturers to seize the market opportunity and survive. This has led to the reorientation of manufacturing values from product-oriented to customer-oriented, and the shift of manufacturing strategic focus from cost and quality to time and response. This can be regarded as an important background for countries to devote themselves to the research and practice of modern manufacturing modes such as CIMS, concurrent engineering and agile manufacturing. The strategy of traditional manufacturing industry is "scale benefit first". In the 1980s, it put forward "price first" and "quality first". Since the 1990s, it has developed into "market response first". Rapid response manufacturing has become an international research hotspot. Automated manufacturing systems are focused on responding to market orders. Nowadays, the market opportunities depend on enterprises to grasp and create. Therefore, the rapid development of products is the leader of rapid response manufacturing, and will become the key to win the international market competition in the 21st century

Since the 1980s, due to the development of optical, mechanical, electrical and material science, a rapid prototyping manufacturing technology (RP) based on the principle of material accumulation has been born. Within a few years, this technology has been widely accepted by the manufacturing industry. With this technology, CAD digital model can be quickly changed into physical model of parts under the control of computer. Therefore, CAD → RP prototype → evaluation → CAD modification has gradually become a new design mode to ensure the success of a design. In the home appliance and automobile manufacturing industry, mold forming parts account for 50% ~ 70% of the manufacturing hours. RT technology based on RP, which has been developed in recent years, can quickly copy RP prototypes into samples of various engineering materials or small batch of functional parts, so as to achieve trial production and trial sales of products, so as to win orders or occupy the market. RT technology can also quickly obtain electrodes to manufacture steel molds. This method can be used to manufacture injection mold, die-casting mold, stamping mold and other precision and complex molds. At present, rapid prototyping technology has been widely used in the fields of automobile, aerospace, shipbuilding, home appliances, industrial design, medical treatment, architecture, handicraft production and children's toys. With the continuous development and improvement of this technology itself, its application range will continue to expand

2 application and cases of rapid prototyping technology in rapid product development

2.1 design evaluation and review of products

in modern product design, design means are becoming more and more advanced, and CAD makes product design quick and intuitive. However, due to the limitations of software and hardware, designers still cannot intuitively evaluate the effect, structural rationality and feasibility of production process of the designed products. In order to improve the design quality and shorten the trial production cycle. The rapid prototyping system can convert the designer's drawings or CAD models into realistic models and samples in a few hours or days. In this way, the pressure test site can be monitored by the camera in real time, the unmanned pressure test site design evaluation can be realized, and the user's feedback on the design can be quickly obtained. At the same time, it is also helpful for product manufacturers to deepen their understanding of products and reasonably determine the production mode and process flow. Compared with the traditional model system, which drives the T-shaped screw pair to drive the load sensor to rise and fall after the deceleration of the variable speed mechanical mechanism, the rapid prototyping method is fast, and can be modified and verified by CAD at any time, making the design perfect

Figure 1 shows a typical case of Northwest rapid prototyping productivity promotion center providing rapid product development services for the medical instrument products of Northwest International Telecom Co., Ltd. This product is a medical electrical product developed by Northwest International Telecom Co., Ltd. for human auxiliary treatment. It is required to have a beautiful appearance, conform to ergonomics, and can be trial assembled at the design stage. (a) in the figure shows the rubber and aluminum manual models made by the user using the traditional method. The production cycle is 15 days, which can not meet the user's design evaluation needs; (b) the figure shows the resin model made by rapid prototyping, which takes 6 hours, which fully meets the user's design evaluation needs. Through trial assembly and shape evaluation, the product shape and functional structure have been modified to meet the ideal requirements. This design verification process makes the design more perfect, greatly shortens the development cycle, and avoids the waste caused by blind production. See Table 1 for the comparison between traditional manual model making and rapid prototyping in product design and evaluation. Table 1 Comparison of traditional manual model making and rapid prototyping in product design and evaluation

from the comparison in the above table, it can be seen that although the cost of rapid prototyping is higher, rapid prototyping has become a necessary link in the development of new products in the market environment where the rapid development of new products has become a bottleneck for the survival and development of enterprises

2.2 product function test

the prototype made by rapid prototyping has certain strength, which can be used for heat transfer, hydrodynamics tests and experimental analysis of product stress and strain under load. For example, in the development of a certain vehicle model to be launched in 1997, GM of the United States directly used the model made by rapid prototyping to conduct the heat transfer tests of the air conditioning system, cooling circulation system and winter heating system in the vehicle, saving more than 40% of the cost compared with the previous similar tests. The traditional process of the development of the missile fuze impeller of the state-run Xi'an Dongfang Machinery Factory is: Design - production of steel mold - Nylon 66 forming - function experiment - design modification. The development cycle is 3-5 months, and the cost is 20000-40000 yuan. Later, the resin model of the impeller is made by rapid prototyping process (Fig. 2a), which is directly used in the ballistic test. The critical speed of the fuze impeller is as high as 50000rpm, the production time is 1.5 hours, and the cost is only 400 yuan, This has greatly accelerated the development of missile fuzes in China. Figure 2B shows the moving and static impellers of automobile air conditioners developed by Jiangyin automobile air conditioner factory. The model made by rapid prototyping is directly used for aerodynamic experiments. After the modification design, the ideal requirements are met, which greatly shortens the development cycle and saves the development cost

2.3 communication means with customers or orderers

at home and abroad, making RP prototypes has become a means for some manufacturers to compete for orders. For example, Xi'an Aoxing Energy Technology Research Institute, using the lps600 rapid prototyping machine of Xi'an Jiaotong University and the rapid tooling manufacturing technology based on it, designed and produced the first functional sample (Figure 3) only within 6 working days after receiving the bid from Xi'an Volvo company, and won the supply contract of oil tank parts with an annual total output value of 10million US dollars among many competitors. On the other hand, customers are always more willing to "dictate" the physical prototype and put forward suggestions on product modification. Therefore, the rapid prototyping model has become the basic condition for communication between the design manufacturer and customers

2.4 rapid tooling

the solid model made by rapid prototyping, combined with precision casting, metal spraying, electroplating, electrode grinding and other technologies, can quickly manufacture the mold. Its manufacturing cycle is generally 1/5 ~ 1/10 of the traditional NC cutting method, but the cost is only 1/3 ~ 1/5. A variety of process methods have been developed according to mold materials, production costs, RP prototype materials, production batches and mold accuracy requirements. This paper only introduces the common process methods and cases of rapid product development

1) use rapid prototyping parts as master mold and make silicone rubber mold

when the number of parts manufactured is small (batch number is 20 ~ 50), RP prototype is generally used as master mold and room temperature vulcanized silicone rubber is used to make silicone rubber mold. Due to the good flexibility and elasticity of silicone rubber, parts with complex structure, fine patterns, no draft angle (even a certain reverse draft angle) and deep grooves can be taken out directly after pouring. This process can produce various plastic parts and paraffin wax models quickly, easily and cheaply. It is widely used in aerospace, sporting goods, toys and decorative equipment. The production cycle is about 1 week. The cost is 1/15~1/20 of the steel formwork

Figure 4 shows the manufacturing case of rapid tooling for telescope shell developed by Yunnan optical instrument factory. By making RP model and reproducing ABS plastic sample with silicon rubber model, Yunnan optical instrument factory has quickly realized new product development, including RP prototype, and the production cycle is 6 days

2) metal spraying method

when the required service life of the mold is less than 3000 pieces, the RP prototype is generally used as the master mold, and the molten metal with low melting point (such as zinc aluminum alloy) is fully atomized and sprayed onto the surface of the master mold at a certain speed to form the cavity surface of the mold, fill the backing composite, and make the zinc aluminum alloy soft mold. The process method is simple, the cycle is short, and the cavity surface and its fine patterns are formed at the same time. The manufacturing cycle is 1 ~ 2 weeks, and the cost is 1/3 ~ 1/5 of the steel mold processed by numerical control method

Figure 5 shows the manufacturing case of the rapid die for drip irrigation developed by the national water saving irrigation center. By making emitter RP model, adopting metal spray molding method to make zinc aluminum alloy soft mold, and injection molding 1000 emitter products for agricultural water-saving irrigation test, the national water-saving irrigation center has quickly realized the trial production of new products, including RP prototype, and the production cycle is 2 weeks

3) use rapid prototyping parts as master mold and make steel mold

when the required service life of the mold is more than 3000 pieces, RP prototype can be used as master mold, and the integral grinding wheel (3D grinding wheel) composed of epoxy resin and silicon carbide mixture can be reproduced to grind the integral graphite electrode on the graphite electrode forming machine, Or Li Hai Zheng polylactic acid project: "corn into plastic" fills the gap in China. Copper is deposited on the surface of RP prototype about 2 ~ 3mm thick by electroforming based on the electrochemical principle. The RP prototype is removed to obtain the electrode shell, filled with backing materials, and made into an integral copper electrode. Using the above integral graphite electrode or integral copper electrode to manufacture a steel die by EDM. The die manufacturing process avoids CNC processing, saves CNC programming and processing time, and has high replica accuracy. The manufacturing cycle of the die is 3 ~ 4 weeks, and the cost is 1/2 ~ 1/3 of the steel die processed by numerical control method

Figure 6 shows the manufacturing case of connecting rod rapid tooling for engine developed by YITUO Group. By making RP model of connecting rod, the graphite electrode of connecting rod is made by integral forming technology of graphite electrode, and the steel die of connecting rod is made by EDM. The production cycle is 3 weeks

3 conclusion

from the above discussion, it can be seen that rapid prototyping technology and rapid tooling technology based on it play an important role in the rapid development of new products in enterprises, which can greatly shorten the development of new products

Copyright © 2011 JIN SHI