Research On The Quotation Method For Small Stamping Dies

Moulds and dies are vital technical equipments in the field of manufacturing industry. The forming method using moulds and dies is applied to industry parts producing widely because of its characteristics of high quality, high efficiency, low cost, low energy consumption, etc. With the development of the modern industry and the sharp shortening of the period of products updating, the demand of moulds and dies expands increasingly, which makes the roles more and more important in the development of all the national economy. The rationality of moulds and dies quotation is related to not only users' benefits but also the payoff levels, formulating the market competitive strategies, realizing preconcerted aims, and so on. So determining the prices of moulds and dies is one of the important contents of managerial decision-making for moulds and dies manufactural enterprises. The conventional quotation methods of moulds and dies, such as quotation by experience, decomposing and collecting, already can't meet the requirement of moulds and dies industry in the new environment because of the shortage of data collecting, difficulty in standardization and normalization. Therefore, it becomes more important that how to compute moulds and dies price scientifically and rationally and evaluate moulds and dies accurately to reflect their actual price.The development of the modern science and technology provides new methods and ideas to resolve these problems, such as fuzzy theory, forecasting technique, computer science, network technique, information technique, database technique, etc. This dissertation puts forward a fuzzy-similarity-comparison method complemented by man-hour method. It simulates human's behavior in the process of conventional experiential quotation, and quantifies the useful information of a new die part and a series of correlative die samples accumulated in the foregone quotation experience by fuzzy membership, and then compares the similarity between the new part and the samples after computing their fuzzy level of approximation to find three of the most similar samples, based on which the producing cost of the new part is estimated by exponential-smoothing-method. Man-hour method is an effectual approach to extend the sample database, and is applied when the number of the correlative samples is insufficient or a new sample is to be added.Based on above, the following main problems are discussed in the dissertation:1. Analysis of the theory, formula composing, the meanings and values of parameters of man-hour quotation. To implement the man-hour quotation method by means of computer and information technologies to release people from long and tedious works of manually computing and collecting material, and to make the quotation more accurate and fast.2. Study the principle and formula derivation of fuzzy-similarity-comparison quotation method, some critical technique such as elemental composition and elemental weights in the parts feature set, normalizing data, selecting similar samples, and so on. The dissertation builds the original feature set, fuzzy memberships and weights of small stamping die, which provides basic principle and method to resolve the practical problem.3. Organizing and establishing the databases of man-hour quotation method and the sample databases of fuzzy-similarity-comparison quotation method. The dissertationconsiders and designs in detail the structure of the sample databases, the selection and addition of the samples, which not only makes the quotation system good in versatility and expandability but also provides a good tool and platform for abstracting the experts' experience later. Well-constructed quotation databases provides ways to extend the sample databases, makes it simpler to maintain the data system and easier to share the information with other systems.According to the quotation method above, a prototype system is developed on the WINDOWS NT platform by POWERBUILD & SQLANYWHERE of SYBASE corporation.