Vol.3 No.1 2010

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Research paper : Acquisition of skills on the shop-floor (N. Matsuki)−81−Synthesiology - English edition Vol.3 No.1 (2010) By fusing the theoretical model where the processing pressure is expressed as a product of the restraint coefficient and deformation resistance, and the model for simplifying the product shape based on experience, we created a computer system that serves as an alternative to the decision values that relied on the decision-making by an expert skilled worker. The measurement values of pressure used in actual processing can be entered and stored in this computer system. By doing so, the values dependent on the factory environment or the processing machine can be estimated.This computer system is one type of simulation for cold forging. In skill transfer, this cold forging simulation can play the following role. First, it can be used as an alternative to the expert skilled worker. If the simulation is perfect, it will be finished there, but the materials and lubricants change with time. Good results may no longer be obtained using the same process if the situation changes. Therefore, the successor must understand the derived model and algorithm that are the basis of this simulation. By understanding the procedure and the principle of the computation, the successor will be able to respond to new situations. In the manufacturing industry that faces severe competition, the ability to do the same work constantly is not sufficient, and the ability to respond to new issues is demanded. In this sense, the simulation in which the principle and the processing procedure are clear can be considered one of the most effective ways to support skill transfer.4.3 Derivation by experimental formulaIn casting, the hardening process of metal plays an important role. The casting technology is a method where precise shapes are created by finely controlling the process of metal solidification. It is possible to an extent to conduct theoretical derivation by entering vast amounts of parameters such as detailed shape of the part, production condition and temperature environment, humidity and temperature of the mold, various properties of the molten metal, and others. However, measuring these figures on site, and entering them to conduct the simulation are very difficult. Also, in casting, the number of parts to be produced with one pour greatly influences the production efficiency and the resultant cost. Company cannot be managed by looking only at the product quality.Considering the various conditions, we thought a mechanism for collecting and storing data that included the algorithm for experimental production based on estimates to some degree was more effective than the simulation format. The material deforms during the heat treatment. It is important to estimate the degree of this deformation. For this purpose, we conducted preliminary experiments at research institutes or companies, selected the degree of deformity and the main parameters that govern the process, and then created the experimental formula. We employed the derived model based on the experimental formula as an alternative to the expert skill of estimating the deformation in heat treatment (Fig. 5).To handle new situations, successors have to employ new experimental formulas as derived models. Therefore, they need to learn the knowledge of physics pertaining to metal materials and to understand engineering to see how the simplification is done. We believe this is the skill turned into technology that the successor should inherit.Contact stress distributionFig. 4 Example of a system for decision-making skills.

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