Automatic centring with moving die for cold small clearance punching of die-quenched steel sheets

Jaafar, H.; Mori, Ken-ichiro; Abe, Yohei; Nakanishi, Kenji

doi:10.1016/j.jmatprotec.2015.08.010

Cited by 15 publications

(4 citation statements)

References 18 publications

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“…The quantity and severity of micro-cracks developed in the vicinity of pierced holes with the distribution of die clearance were investigated in [15]. Jaafar et al [16,17] developed a model to provide the eccentricity in the cutting of ultra-high strength steel sheets. In their model, a moving die provided the eccentricity between die and punch.…”

Section: H Gürün M Göktaş a Güldaş Experimental Examination Of Ementioning

confidence: 99%

Experimental Examination of Effects of Punch Angle and Clearance on Shearing Force and Estimation of Shearing Force Using Fuzzy Logic

2016

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SummaryA significant challenge faced when using blanking/piercing to machine sheet metal is the handling of the shearing force required for high strength and thick stock. Increased shearing forces lead to the requirement of higher performance expected from the pressing machine and result in increased wear on the punch tool and die. Clearance, employed to increase precision and quality in blanking/piercing operations, affects the shearing force as well. One of the techniques used to reduce the force required is the employment of a punch shear angle. In this study, the effects of punch shear angle and clearance on the forces required for blanking/piercing were examined on a grade of steel broadly used in the manufacturing industry, DC01. Experiments were carried out using five different punch shear angles, namely 0°, 2°, 4°, 8°, and 16°. Six matrices with varying clearance rates (0.4%t, 0.5%t, 0.6%t, 0.7%t, 0.8%t, and 0.9%t) were used in this study, and these clearances were altered by modular matrices on the die. This study shows that shearing forces can be reduced by 80 % when 16° punch angle is used. The results of the experiments were transferred to a fuzzy logic model to obtain extrapolated results for intermediate values which had not been obtained from the experiments. The results obtained from the experiments and the output from the fuzzy logic model were compared and found to be highly similar. These results have showed that the model developed using fuzzy logic can be used to determine different shear angles and clearance values.

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Section: H Gürün M Göktaş a Güldaş Experimental Examination Of Ementioning

confidence: 99%

Experimental Examination of Effects of Punch Angle and Clearance on Shearing Force and Estimation of Shearing Force Using Fuzzy Logic

2016

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“…In this process, not only the burnished surface of the sheared edge increases, but also the residual stress becomes compressive. Jaafar et al [29] introduced automatic centering with a moving die into the slight clearance punching process in order to simplify setting of the punch having a small round corner and prevented the occurrence of delayed cracking for punched 1.5 GPa sheets by the compressive residual stress. On the other hand, Mori et al [30] ironed a hole of a punched ultra-high strength steel sheet with a taper punch in order to smooth the sheared edge, and Kadarno et al [31] developed a punching process including thickening around a hole with a taper punch and step die.…”

Section: Introductionmentioning

confidence: 99%

Prevention of delayed cracking of punched 1.5 GPa ultra-high strength steel sheets by ironing with punched slug

Mori

Abe

Murai

2020

Int J Adv Manuf Technol

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Hydrogen-induced delayed cracking of punched 1.5 GPa ultra-high strength steel sheets was prevented by ironing with a slug ejected from punching, because the risk of delayed cracking for sheared 1.5 GPa sheets is very high due to high tensile residual stress and large plastic deformation. To prevent the occurrence of delayed cracking, the sheet was punched, and then, the punched hole was ironed by passing the punched slug. Although the residual stress around the punched edge of the 1.5 GPa sheet was tensile, the stress was turned to compressive stress by slug ironing. In addition, the fracture surface of the sheared edge was changed to a smooth ironed surface. A cathode hydrogen charging test of the punched edge for delayed cracking was performed. Although delayed cracks were caused at the punched hole by hydrogen charging, no cracks occurred at the ironed hole for charging. It was found that slug ironing of the punched hole is effective in preventing delayed cracking.

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“…Existing centering methods mainly involve either contact or non-contact approaches. Contact methods include the dial-indicator method, the three-point method, 6 and the orthogonal-point electrical contact method. 7 Non-contact methods involve things like laser alignment 8 and image centering.…”

Section: Introductionmentioning

confidence: 99%

A nested circle-fitting method for micro-hole centering and its application in electrochemical deburring

Kong

Liu

Fan

et al. 2019

Proceedings of the Institution of Mechanical Engineers, Part B:

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To solve these problems (i.e. the accuracy rate and stability of the centering) of enabling secondary machining of micro-holes with a size of 0.1 to 1 mm in high-performance metal alloy parts, a non-standard nested circle-fitting least-square method, with a linear constraint passing through the center (least square method with linear constraint [LSLC]), is proposed in this article. The experimental results show that the center of the circle is fitted with a maximum deviation of ±1.5 µm and good fitting precision, compared to other existing approaches. At the same time, the accuracy rate is increased by at least 20%, delivering a result of more than 99%, so the accuracy of the fitting and the stability of the centering are significantly improved. Finally, the new method is applied in actual micro-hole electrochemical deburring study. With the overall goal of ensuring centering, a rough-and-fine deburring process has been explored. On the premise that the hole is not expanded, the burrs have been quickly and completely removed, and machined surface roughness, Ra, has also reduced from 1.2 to 0.52 µm. The experiment has provided concrete validation of the feasibility of the nested circle-fitting method we have proposed.

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Automatic centring with moving die for cold small clearance punching of die-quenched steel sheets

Cited by 15 publications

References 18 publications

Experimental Examination of Effects of Punch Angle and Clearance on Shearing Force and Estimation of Shearing Force Using Fuzzy Logic

Experimental Examination of Effects of Punch Angle and Clearance on Shearing Force and Estimation of Shearing Force Using Fuzzy Logic

Prevention of delayed cracking of punched 1.5 GPa ultra-high strength steel sheets by ironing with punched slug

A nested circle-fitting method for micro-hole centering and its application in electrochemical deburring

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