[机械模具数控自动化专业毕业设计外文文献及翻译]【期刊】大型数控机床的系列设计-外文文献

Jun. 2007 Journal of China University of Mining & Technology Vol.17 No.2 J China Univ Mining & Technol 2007, 17(2): 0272& 0276 Series Design of Large-Scale NC Machine Tool TANG Zhi Engineering and Mechanical Institute, Donghua University, Shanghai 201620, China Abstract: Product system design is a mature concept in western developed countries. It has been applied in war industry during the last century. However, up until now, functional combination is still the main method for product system de-sign in China. Therefore, in terms of a concept of product generation and product interaction we are in a weak position compared with the requirements of global markets. Today, the idea of serial product design has attracted much attention in the design field and the definition of product generation as well as its parameters has already become the standard in serial product designs. Although the design of a large-scale NC machine tool is complicated, it can be further optimized by the precise exercise of object design by placing the concept of platform establishment firmly into serial product de-sign. The essence of a serial product design has been demonstrated by the design process of a large-scale NC machine tool. Key words: large-scale NC machine tool; series product design; optimized design CLC number: TH 12 1 Introduction Large-scale machine tool designs are management programs requiring participation of different disci-plines including engineering, behavioral studies, color research, ergonomics and corporate identity1. At present, functional designs are emphasized in China, while in western countries the multi-color identity system and series product definitions have entered the field of industrial design. It is quite com-mon in China to imitate products from Taiwan and other similar territories, resulting in the phenomenon where many products in the market are of the same quality. There are almost no differences among large-scale numerical controlled (NC) machine tools made by different factories. It is vital to introduce series product designs into the Chinese production processes. Back in the 1930s, the designers in GM adopted a new design mode, i.e. planned obsolescence2. Ac-cording to this plan, the style of cars at least should have small changes every two years and dramatic changes every 34 years, which provide regularly a new style of cars. The aim of the plan was to con-vince customers to give up their old cars and to pur-sue the new style. Theoretically, planned obsoles-cence established serial product designs, elevated planned product design to the level of management decisions inside the company and increased sales be-cause of the introduction of serial product designs. From the 1930s to the 1960s, system designs did not improve much due to the financial crisis and the Second World War. However, the requirement of the war had stimulated mass production of consumer products, after generating a large number of cheap industrial products, a spinoff from the war. After the Second World War, system designs and serial product designs developed by GM and a number of other car manufacturers emerged in Italy, the UK and Germany. This was especially true for the ULM Design Institute whose system of industrial designs became the stan-dard for scientific application of industrial designs. This developed to an advanced level and much atten-tion was directed to cooperation among firms. It is clear that the effect of such changes on, for example, BRAUN , was very significant3. From 1960 to 1970, Japan started product development on a multi-na-tional company level, while at the same time the Japanese government established industrial product export norms. During the last 20 years, a number of institutions and organizations have been engaged in research of design processes, design methods, and design management4. At present, in terms of the serial design of a Received 12 October 2006 accepted 15 November2006 Corresponding author. Tel: E-mail address: TANG Zhi Series Design of Large-Scale NC Machine Tool 273large-scale NC machine tool, it is important to main-tain the inner characteristics of the firm, which is the core of the serial design system. Fig. 1 is the proto-type of a large-scale NC machine tool from a particu-lar company in China. Fig. 1 Original prototype of machine tool The style of the original prototype of the machine tool in Fig. 1 is actually consistent with design sys-tems of the middle of the 20thcentury. It has some problems: 1) bare engine; 2) sharp angle style of the corner; 3) accessories do not match the main machine; 4) line arrangement is not orderly; 5) open style of the door is out of date; 6) single color, lack of the inden-tification and 7) entire style is dated, falls short of advanced product identity system. Therefore this style is too direct in expressing the function and form of the product. It is important therefore, that its essen-tial functional features are consistent with the design of a serial product. 2 Product Identity System Generally, the product identity factor determines the behavior of a particular company, which is the very essence of the product identity system, i.e.,to identify clearly with a particular product. Therefore, the identity system should 1) be able to attract maxi-mum social attention, 2) agree with the visual con-ceptual standards of the company, 3) be provided with a characteristic logo, 4) be able to impress others, 5) meet the needs of different types of products, 6) conform to aesthetic taste and 7) does not signifi-cantly increase production costs caused by the devel-opment of the new design. From the point of view of product identity, these are the requirements in order to raise the price of the product and meet market competition. Similar to the “sense and simplicity” of the Philips label, the em-bodiment of its core value is the key for a company to obtain the enthusiastic acceptance from the public. Its platform establishment, optimized design and modu-lar management should be introduced as the main factor of serial products to support the product iden-tity system at the company level5. Fig. 2 is the diagram of design platform. Before establishing the identity system, a common platform for a large-scale serial NC machine tool needs to be provided and then optimized in order to determine which platform suits the design of a par-ticular product. Therefore, the platform is the key for the future serial product. Fig. 2 Introduction of design platform 3 Establishing Platform for Product 3.1 Process of platform establishment For different structures of product integration, the platform is usually the most effective way to deter-mine the cost. The time for design can be reduced and productivity can be raised because of anamorphic products from the repeated platform. Especially, for a large-scale NC machine tool, it is important that the customized products for specific regions are easily and effectively adopted on the established product platform6. The purpose for establishing a platform is not for the product function but for concentrating on the de-sign of the serial product and on other systems relat-ing to product technology. In terms of the platform, the engineering team should build a model of the product system which involves the system framework for describing the product precisely and then report-ing to the designer as a reference for establishing the platform (Fig. 3). 3.2 Evaluation of the platform establishment Following are four basic evaluation criteria7: 1) Material cost and production cost (which will influence the final price of the product). 2) The cost of inventory. 3) Visual requirement. 4) Ergonomics. Enumeration of these criteria is the basis for serial product differentiation. Fig. 4 shows a list of the se-rial products for four alternative projects. The prod-ucts are listed on the top of the chart and are pre-sented as columns. The serial products are divided into parts for analytical convenience. Four different series are presented at four different platforms in which series A involves a power supply, series B in-volves a power supply, an oil slot and wiring, series C involves a power supply, a base and a line controller and series D involves a power supply, an oil filter and Journal of China University of Mining & Technology Vol.17 No.2 274an electrical source. Their scores are recorded ac-cording to the following rule: 1) the base design, “0”; 2) better than base design, “+”; 3) worse than base design, o ”. Fig. 3 Platform of design process for machine tool Sort of product Sort 1 Sort 2 Sort 3 Sort 4 Chose platform A B C C A B C C A B C C A B C C Materials cost 0 0 0 0 0 0 0 0 Development cost 0 0 Requirement of vision 0 0 0 0 0 0 0 0 EvaluationcriteriaErgonomics 0 0 0 0 Summary 0 1 2 2 2 2 2 2 2 2 2 2 1 1 0 0 Fig. 4 Selection chart of product platform and serial products After the evaluation, we obtain an aggregate score, which is the basic optimized platform project. For a project such as the large-scale NC machine tool, however, it is vital to build a partly optimized design for product parts. 4 Optimized Design of Product The optimized product design is usually not aimed at the platform but at a particular product and in the structural design, it should follow the function, such as the improvement of the door style of our machine tool. The platform and single optimized product de-signs are usually adopted in large-scale equipment. By taking advantage of the basic platform, new, ab-normal products can be easily be developed. Modular development, armature plate techniques and quickly formed skills come quite easily and are sufficient to meet the needs of the market. However, there are some disadvantages to a basic platform. Generally speaking, in a series only one product is compara-tively successful in material and development costs, visual requirements and human factors. This is the so-called flagship product with respect to other lower level serial products. Assume product i was a singular design, not based on a platform, so it can be expressed as an optimiza-tion problem. Now let us try to optimize an obj ctive function in terms of the structural variableief xG, re-stricted by the function g, cost and other constraints8, then we have ()minpixf xGGrestriction function , () 0igxGbudget restriction ( )ii icost x BG , where g stands for a restriction function, cost for se-rial products and B for budget. The planned work based on the platform can construct an optimized model. Before selecting the product platform, we must first determine what are the common parts and what can be isolated as an anamorphous part. When the cost of every anamorphous part is decreased to its lowest level, the cost of the whole series is also re-duced to the lowest level. So, the optimization should be operated at two layers, namely the platform and anamorphous part. The product function based on the platform is decided by the variable, the part shared with the same platform could be described by the variable set. As well, the formula can also be used in the design of a single product i . On the platform and for the variable concerned, different optimization TANG Zhi Series Design of Large-Scale NC Machine Tool 275processes can be made flexible. The optimized issue is described by minpxG ()min ,iyipyxifxx GGGFunction limit (),0iipygxxG G , Budget limit ( ),iipyicost x x BGG , where B is the budget of the serial product. This mathematical expression is a simple descrip-tion for the optimization process. Actually we still adopt a small scale modular design for the details. For these large-scale NC machine tools, the modular de-sign is very good for it can deal with the details of the inner parts of the product, resulting in a low cost of R&D and inventory. Moreover, the optimized design can be applied in the function modular combination, just like the big difference would appear on different sized machine tools in the structure and quantity of the doors. However, the optimized design needs some adjustment for the installment of the console and wiring set to fit the size and the application. 5 Module Design of Product Standardization of accessories and a quick forming of the shape are the two main advantages of the modular design. Based on these two characteristics, a modular product generally can be divided into several layers in one system9. However, because of the un-derstanding from the different angles, the standard and the result of the module are not unique; the final relationships of sub-functions are probably a holistic or modular construction. There are two product modules: one based on a functional module and the other based on a produc-tion module. The first one is set from the general product function and is expressed by its sub-function. For the second, the production takes into considera-tion the combination of some accessories in the manufacturing process, forming the assembled mod-ule (Fig. 5). The module mentioned here is at a con-ceptual level; its function has the characteristics of production and assembly. Fig. 5 Design module of product system structure 6 Parameter Set of Serial Product 6.1 Size parameter In terms of complicated products like our large- scale NC machine tool, the determination of parame-ters is quite important. Its functionalism is always the first thing to be considered when we regulate the rela-tive size. These days, undoubtedly, the products that are subjected to global competition, increasingly are ergonomic designs of classical products and become the preferred products on a worldwide level. In the design of a flagship product, one from a se-rial product, the redundant, complicated and de-humanizing details have been eliminated from the design according to certain standards. In the design process, the aesthetic, structure and interaction must be taken into consideration. Clearly, the base of the machine tool and the power supply can be a 3D iden-tity standard (Fig. 6), i.e., the symbolized design of the new product. So the size and proportional pa-rameters are regulated. For different kinds of propor-tional parameters, seen in Fig. 7, the proportion of the doors, moveable doors and power supply have been presented. All of the parameters are determined based on ergonomics, especially given the body scale of Asiatic people 10. Fig. 6 New machine tool concepts 6.2 Parameter set up by the chart As Fig. 4 shows, there are four sorts of products, each has four platforms named A, B, C and D. Engi-neers are asked to choose which platform is appropri-ate for each sort of product. They are also asked to rate the remaining four factors: material cost, devel-opment cost, visual requirement and ergonomics, corresponding to each sort of product11. Journal of China University of Mining & Technology Vol.17 No.2 276Fig. 7 Engineering chart design standard 7 Conclusion The inevitable result from a serial product design is a real product. It is necessary to adjust the parameter set in the process of final assembly. Any single product which can occupy the target market will become well known in the