製鋼作業における品質管理實施の一例 : 下注鋼塊單重の變動要因と管理について

概要

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It is easily recognized that improved and stable yield in rolling shop and guarantee of billets quality depend on the controlled ingots weights. The variation of weights of bottom-cast ingots were statistically investigated through several experiments and the following application of statistical quality control was carried out to the sources of variations 1. Principal source of weight variations between stools was the height of castings. Therefore the heights of castings were controlled by the improvement of casting operation and the control charts of average weight of respective stools. 2. It was found that the factor of weight variation between stools depended on the inner valume of mould, and the dimensional tolerance was decided to specify ±3 mm which was severer than the former tolerance ±5 mm. Most of ingot moulds now purshased are within the tolerance of ±3 mm. 3. Training of works and operation in accordance with standard directions were practiced in order to control the casting conditions. As a result of these controls, the standard deviation of ingot weight was improved from the former σ=20kg to σ=16kg. Consequently the standard ingot weight was reduced to the yield in a rolling shop increased by 0.5%, and billets quality was more guaranteed.
社団法人日本鉄鋼協会の論文
1954-04-25