Vol.5 No.2 2012

35/66

Research paper : Toward the integrated optimization of steel plate production process (K. Nishioka et al.)−109−Synthesiology - English edition Vol.5 No.2 (2012) pattern of finishing processes (rows of 01 indicating yes or no of completion (a pass) ) based on the manufacturing specification, (2) a system to estimate a lead time distribution by each product type is introduced by defining as one group a character string that has added to this completion pattern a category code representing product types grouped in a major category. The category code was added because even though it concerns the same completion pattern, the completion frequency (occurrence rate) of the occurrence process differs and there are cases where the lead time distribution differs. Even though the completion pattern and the completion frequency are the same, depending of the product type, there are cases where the set value of the delivery success rate differs.For plate manufacturing, for which it is unknown at the time of deciding the order specification which processes for the intermediate goods to pass, such as surface grinding or gas cutting and flattening, and where there are occurrence processes determined regarding their completion after rolling, it is therefore not possible to calculate the completion pattern of finishing processes with a simple logic based on the manufacturing specification of the order. Therefore, using the decision tree that is a methodology used generally for data mining, we developed a completion pattern estimation model.When seeking the lead time distribution of each product type to be manufactured, the simple method is to collect plates of the same manufacturing product type from the existing data, and use the histogram of their actual lead time data to draw the lead time distribution. However, there are also product types that are manufactured rarely, and the lead time distribution of such product types with a small number of data tends to be low in reliability. Therefore, we adopted a method to obtain the lead time distribution for every production type to be manufactured by obtaining the lead time distribution for each completion pattern and by dividing it proportionally by the component percentage of the completion pattern for each type of product to be manufactured.Note 4) The technical group in addition assumes the roles of transmitting information to the works' top management (accountability on behalf of the line division, or representing the technical division), coordination with the relevant staff department involved with short-term issues relating to line management (production technology, production scheduling, general affairs, personal affairs, labor, equipment), planning of middle and long-term plans, development of R & D strategies with the R & D department, and the role of overall coordination for various problems that occur mainly with the line division, including areas for which the job description is not necessarily clear such as the coordination with staff department based in the head office. TerminologyTerm 1.Manufacturing lead time: A term used in the steel industry, signifying the duration of time required for manufacturing. Its definition is varied including the duration of time from receiving an order to the delivery of a product and from the start of manufacturing to its completion, but in this paper, it is defined as the time required from the start of rolling a plate to the completion of its manufacturing.Term 2.Manufacturing processes in a steelworks: A steelworks manufacturing steel products in an integrated manner from iron ore is called an integrated iron and steelmaking works and its processes are generally classified into three processes of ironmaking, steelmaking and rolling, the first consisting of ironmaking by reducing iron ore in a blast furnace; the second in steelmaking by removing carbon from pig iron and adding necessary alloy elements in a converter; and the third in manufacturing various products by rolling semi-products manufactured in the steelmaking process. A steel plate mill is one of the rolling processes and it rolls and produces steel plates.Term 3.Rolling efficiency: Efficiency indicates the ratio of work accomplished in a given amount of time. Because the rolling process has a series of equipment for heating, rolling, cooling, etc. that are arranged continuously in tandem and are directly connected, the efficiency of continuously making such series of equipment function is called rolling efficiency.Term 4.Correction (flattening) process: The process where a defect in flatness detected after the rolling process of plates is corrected by a roller leveler or a press.Term 5.Habitus: As a concept similar to habitus, there is tacit knowledge [Polanyi, M.: The Tacit Dimension, Doubleday Anchor, N.Y. (1967)]. Habitus can be considered as tacit knowledge in scientific activities and is the expertise in the broad sense of the term related to the method of conducting research.References[1]J.P. Womack and D.T. Jones: Lean thinking, Nikkei BP, Tokyo (2008) (in Japanese).[2]T. Enkawa, M. Kuroda and Y. Fukuda: Seisankanri No Jiten (Dictionary of production control), Asakura Shoten, Tokyo (1999) (in Japanese).[3]A. Yoshie: Atsuita-2 (Steel Plate-2), Nippon Steel Monthly, 6 (169), 7-10 (2007) (in Japanese).[4]T. Ohno: Toyota Seisan Hoshiki (Toyota Production System), Diamond Inc., Tokyo (1978) (in Japanese).[5]J.P. Womack, D.T. Jones and D. Roos: The Machine That

※このページを正しく表示するにはFlashPlayer9以上が必要です