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1

Effect of sheet thickness on deep drawing of metal foils

Marumo Y., Saiki H., Ruan L.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 20, nr 1-2

479-482

EN

Purpose: The objective of the present work is to study the influence of sheet thickness on blank holding force and limiting drawing ratio. Design/methodology/approach: Variation in blankholding force and limiting drawing ratio in deep drawing of metal foils were evaluated by calculation. Findings: The paper shows variation in the blankholding force required for the elimination of wrinkling and the limiting drawing ratio with sheet thickness. The blankholding force required for the elimination of wrinkling increased rapidly as the sheet thickness decreased. When the sheet thickness was very thin, the blankholding force was strongly influenced by the coefficient of friction. The limiting drawing ratio decreased as sheet thickness decreased and it decreased rapidly below 0.04 mm thickness. When the sheet thickness was very thin, the limiting drawing ratio was strongly influenced by the coefficient of friction. Research limitations/implications: The control of the loading path of blankholding force will be an effective way to prevent the formation of defects including fractures and wrinkles in deep drawing of metal foils. Practical implications: When deep drawing of metal foils is carried out, the control of loading path of blankholding force during deep drawing operation can be very effective for improving the limiting drawing ratio. Originality/value: The contribution of the conducted reseach is observed in a possible view of improvement of deep drawability of metal foils.

2

Influence of micro asperity-valley on the surface of forging tools on tribological conditions

Saiki H., Marumo Y., Ruan L.

Computer Methods in Materials Science

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2007

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Vol. 7, No. 1

101-105

PL

Zależności pomiędzy współczynnikiem tarcia, chropowatością powierzchni i granicą plastyczności środka poślizgowego w formie stałej są badane w niniejszej pracy z wykorzystaniem sztywno plastycznego modelu elementów skończonych. W pracy przeprowadzono szczegółową dyskusję zależności pomiędzy wymienionymi czynnikami, określając zoptymalizowane parametry trybologiczne prowadzenia procesu.

3

Examination of conditions in contact interface using ultrasonic measurement

Saiki H., Marumo Y., Ruan L., Matsukawa T., Zhan Z. H., Sakata Y.

Archives of Materials Science and Engineering

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2007

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Vol. 28, nr 2

113-118

EN

Purpose: In metal forming, the conditions of contact interface have a great effect on the characteristics of interface friction and heat transfer between tool and workpiece. Estimation of contact conditions in the toolworkpiece interface is required in order to optimize process conditions. Ultrasonic examination is an effective method to estimate the contact conditions. In this study, we investigated the effects of ultrasonic frequencies and intermediate air/lubricant films in the contact interface on the properties of penetration and reflection of incident ultrasonic waves. Design/methodology/approach: We have presented a method by which the contact conditions are evaluated from the relative intensity of reflected ultrasonic waves at the interface. Using this evaluation method, the relative intensity was measured continuously during processes. Findings: The effects of ultrasonic frequencies and intermediate films on the properties of penetration and reflection of incident ultrasonic waves were revealed. The presented method was effective for evaluating the variation of contact interface conditions. Research limitations/implications: Thickness of intermediate films can be measured using this ultrasonic examination. The performance of lubricants can be estimated. Practical implications: The optimization of forming processes will be achieved based on the evaluation results of contact conditions. Originality/value: Tribological conditions including intermediate air/lubricants were evaluated by ultrasonic examination. This shows the possibility that the lubricant behaviour in the contact interface is examined during processes.