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Effect of use of protrusion punch on length of burnished surface in piercing after half punching
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Procedia Manufacturing 00 (2018) 000–000 Available online atatwww.sciencedirect.com Available www.sciencedirect.com Procedia online Manufacturing 00 (2018) 000–000
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Procedia Manufacturing 15 (2018) 653–659 Procedia Manufacturing 00 (2017) 000–000 www.elsevier.com/locate/procedia
17th International Conference on Metal Forming, Metal Forming 2018, 16-19 September 2018, 17th International Conference on MetalToyohashi, Forming, Metal Japan Forming 2018, 16-19 September 2018, Toyohashi, Japan
Effect of use of protrusion punch on length of burnished surface in Effect of useEngineering of protrusion punch onConference length of burnished surface in Manufacturing Society International 2017, MESIC 2017, 28-30 June piercing after half punching 2017, Vigo (Pontevedra), Spain piercing after half punching Masahiro Sasada*, Syuu Katou Costing models for capacity in Industry 4.0: Trade-off Masahirooptimization Sasada*, Syuu Katou Department of Mechanical Engineering, Kanagawa University, Rokkakubashi 3-27-1, Kanagawa-ku, Yokohama, Kanagawa,221-8686, Japan between used capacity and operational Department of Mechanical Engineering, Kanagawa University, Rokkakubashi 3-27-1, Kanagawa-ku, efficiency Yokohama, Kanagawa,221-8686, Japan
Abstract A. Santanaa, P. Afonsoa,*, A. Zaninb, R. Wernkeb Abstract a Shearing is a cutting method with high productivity. The cut4800-058 surfaceGuimarães, consists ofPortugal a shear droop, a burnished surface, a fractured University of Minho, Shearingand is aburr. cutting high productivity. The89809-000 cutfractured surface consists of a shear droop, obtained a burnished surface, atofractured surface Pressmethod shavingwith removes thebshear droop and surface the cut surface by shearing increase Unochapecó, Chapecó, SC,on Brazil surface andof burr. shaving removes shear droop the and trimming fractured surface on the cut to surface obtained shearing to of increase the length thePress burnished surface. In the press shaving, allowance is set a small value.by The amount chips the length of the burnished surface. In press shaving, the trimming allowance is set to a small value. The amount of chips obtained by press shaving is very small. The occurrence of small chips is a problem for press working. Therefore, it is desirable obtained byburnished press shaving is very small. The occurrence of smallof chips is chips. a problem forpiercing press working. Therefore, it isallowance desirable that a large surface is obtained without the occurrence small When with a small trimming Abstract that apreviously large burnished is obtained without the occurrence of small chips. piercing small However, trimming allowance was carriedsurface out after half punching, a chip was connected to the sheetWhen material underwith the apunch. the length was previously after half punching, chip was connected the sheet material underhalf the punching punch. However, the length of the burnishedcarried surfaceoutwas decreased. In thisastudy, piercing using to a protrusion punch after was carried out to of the burnished surface was decreased. In this study, piercing using a protrusion punch after half punching was carried out to Under the concept of "Industry 4.0", production processes will be pushed to be increasingly interconnected, increase the length of the burnished surface. The effect of the use of a protrusion punch on the length of the burnished surface increase the length burnished Thenecessarily, effect of the much use of more a protrusion punch on the length of the burnished surface information based ontheawas realinvestigated. time surface. basis and, efficient. In this context, capacity optimization and the shape of theof chip and the shape of chip was investigated. goes beyond thethe traditional aim of capacity maximization, contributing also for organization’s profitability and value. © 2018 The Authors. Publishedand by Elsevier B.V. improvement approaches suggest capacity optimization instead of Indeed, lean management continuous © 2018 2018 The The Authors. Authors. Published Published by by Elsevier Elsevier B.V. © B.V. Peer-review under responsibility of the scientific committee ofcosting the 17th 17thmodels International Conference on MetalForming. Forming. maximization. The study of capacity optimization andof is anConference importanton research topic that deserves Peer-review under responsibility of the scientific committee the International Metal Peer-review under responsibility of the scientific committee of the 17th International Conference on Metal Forming.
contributions from both the practical and theoretical perspectives. This paper presents and discusses a mathematical Keywords: Shaearing, Protrusin punch, Chip, Burnished surface, Half punching model for capacity management based on different costing models (ABC and TDABC). A generic model has been Keywords: Shaearing, Protrusin punch, Chip, Burnished surface, Half punching developed and it was used to analyze idle capacity and to design strategies towards the maximization of organization’s value. The trade-off capacity maximization vs operational efficiency is highlighted and it is shown that capacity 1. Introduction optimization might hide operational inefficiency. 1. Introduction © 2017 The Authors. Published by Elsevier B.V. Shearing is a cutting method with high productivity. The cut surface consists of a shear droop, a burnished surface, Peer-review responsibility of with the scientific committee ofThe the Manufacturing Engineering Society International Conference Shearingunder is a cutting high productivity. cut surface consists of a shear droop, a burnished surface, a2017. fractured surface and method burr. Press shaving removes the droop and fractured surface on the cut surface obtained by a fractured Press shaving removes the droop fractured surface on the cut surface obtained shearing to surface increaseand theburr. length of the burnished surface. Pressand shaving consists of two stages. The first stage isbya shearing to increase the length of the burnished surface. Press shaving consists of two stages. The first stage is a Keywords: Cost Models; ABC; TDABC; Capacity Management; Idle Capacity; Operational Efficiency 1. Introduction
* Corresponding author. Present address: Doshisha University, Kyotanabe, Kyoto, 610-0394, JAPAN Tel.: +81-774-65-6556. * E-mail Corresponding Present address: Doshisha University, Kyotanabe, Kyoto, 610-0394, JAPAN Tel.: +81-774-65-6556. address:author. [email protected] The cost of idle capacity is a fundamental information for companies and their management of extreme importance E-mail address: [email protected]
in modern©production systems. In general, it isB.V. defined as unused capacity or production potential and can be measured 2351-9789 2018 The Authors. Published by Elsevier 2351-9789 2018 Authors. Published Elsevier B.V.hours of the Peer-review underThe responsibility of theby scientific committee 17th International on Metal Forming. in several©ways: tons of production, available manufacturing, etc.Conference The management of the idle capacity Peer-review under responsibility thefax: scientific committee * Paulo Afonso. Tel.: +351 253 510of 761; +351 253 604 741 of the 17th International Conference on Metal Forming. E-mail address: [email protected]
2351-9789 © 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the scientific committee of the Manufacturing Engineering Society International Conference 2017. 2351-9789 © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the scientific committee of the 17th International Conference on Metal Forming. 10.1016/j.promfg.2018.07.291
Masahiro Sasada et al. / Procedia Manufacturing 15 (2018) 653–659 Author name / Procedia Manufacturing 00 (2018) 000–000
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blanking or punching stage and the second stage is a shaving stage. The relationship between several press shaving characteristics and the shaving allowance has been investigated by an experiment and FEM [1]. Improving the cut edge by counter-shaving has been investigated [2]. The shaving of stacked sheet materials has been carried out to reduce the area of the fractured surface [3]. These useful researches have been reported. In the shaving stage, the trimming allowance is set to a small value. Therefore, the amount of chips obtained by press shaving is very small. The occurrence of small chips is a problem for press working. It is desirable that a large burnished surface is obtained without the occurrence of small chips. When piercing with a small trimming allowance was carried out after half punching, a chip was connected to the sheet material under the punch [4]. However, the length of the burnished surface was decreased. In this study, piercing using a protrusion punch after half punching was carried out to increase the length of the burnished surface. The effect of the use of a protrusion punch on the length of the burnished surface and the shape of chip was investigated. 2. Experimental method Experiments consisted of two stages. In the first stage, half punching with a negative clearance was carried out, and in the second stage, piercing using a protrusion punch was carried out. The experimental equipment is shown in Fig. 1(a). An aluminum (JIS A1100P-O) sheet with a length and width of 40 mm and a thickness of 2 mm was used. The blank holding force was set to 2370 N. A paraffin-type base oil (kinematic viscosity 90×10-6 m2/s) was applied to both surface of the sheet material before starting the punching. The punch displacement was measured using linear position sensors mounted on the dieset. The punching speed was set to 0.1 mm/s. In the first stage, half punching with a negative clearance was carried out, where the diameter of the punch was 5.8 mm and the clearance was set to -5% of the sheet material thickness. The punch penetration depth (Ps1) was set to 1.4 mm. In the second stage, piercing using a protrusion punch was carried out. An illustration of the protrusion punch is shown in Fig. 1(b). The diameter of the punch was 6 mm, the diameter of the protrusion (Dpr) was set to 5.0, 5.5 or 5.8 mm and the length of the protrusion (Lpr) was set to 0.3 or 1.0 mm. The clearance was set to 5% of the sheet thickness. Conventional punching was also carried out with the diameter set to 6.0 mm. In addition, conventional press shaving was carried out, where the clearance was 5.0% and the trimming allowance was 5%. The diameter of the punch was also set to 6.0 mm for the shaving stage. The experiment was conducted three times for each experimental condition. Then the lengths of shear droop, burnished surface, fractured surface and burr were measured from photographs of cross sectional view. (a)
(b) Load cell
Pilot pin
Displacement sensor Blank holder Lpr
Punch
Die Dpr
Fig. 1. (a) Experimental apparatus for first and second stages and (b) protrusion punch.
3. Experimental results 3.1. Holes and scraps for Lpr =1.0 mm The cross sectional views of the hole and scrap obtained by punching using the protrusion punch with Dpr = 5.0 mm and Lpr = 1.0 mm are shown in Fig. 2. The chip obtained in the second stage was not connected to the scrap
Masahiro Sasada et al. / Procedia Manufacturing 15 (2018) 653–659 Author name / Procedia Manufacturing 00 (2018) 000–000
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under the punch. Cross sectional view of the hole and scrap obtained by punching using the protrusion punch with Dpr = 5.5 mm are shown in Fig. 3. Cross sectional views of hole and scrap obtained by punching using the protrusion punch with Dpr = 5.8 mm are also shown in Fig. 4. The chip was not connected to the scrap regardless of Dpr. However, the length of the burnished surface increased with increasing Dpr. The length of the fractured surface on the hole is shown in Fig. 5. In the case of Dpr = 0.0 mm, piercing using the punch without the protrusion was carried out in the second stage. Cross sectional view of the hole and scrap obtained by piercing after half punching are shown in Fig. 6. When Dpr was 0.0 mm, the length of the fractured surface was larger than the length of the remaining thickness (0.6 mm) after the first stage. The length of the fractured surface was smaller than the length of the remaining thickness after the first stage in the cases of Dpr = 5.5 and 5.8 mm. (a)
(b)
(c)
Fig. 2. (a) Hole, (b) scrap and (c) chip for Dpr = 5.0 mm and Lpr = 1.0 mm. (a)
(b)
(c)
Fig. 3. (a) Hole, (b) scrap and (c) chip for Dpr = 5.5 mm and Lpr = 1.0 mm. (a)
(b)
Fig. 4. (a) Hole and chip and (b) scrap for Dpr = 5.8 mm and Lpr = 1.0 mm.
Masahiro Sasada et al. / Procedia Manufacturing 15 (2018) 653–659 Author name / Procedia Manufacturing 00 (2018) 000–000
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Length of fractured surface (mm)
1
0.8
0.6
0.4
0.2
0
0
1 2 3 4 5 Diameter of protrusion Dpr (mm)
6
Fig. 5. Relationship between length of fractured surface and diameter of protrusion for Lpr =1.0 mm. (a)
(b)
Fig. 6. (a) Hole and chip and (b) scrap for Dpr = 0.0 mm.
The deformation process in the second stage for Dpr = 5.0 mm is shown in Fig. 7. For Ps2 = 0.5 mm, a chip was formed by the punch edge and the scrap was pushed by the protrusion. When Ps2 was 1.0 mm, the scrap was separated from the sheet material on the die by the protrusion. When Ps2 was 1.5 mm, the piercing continued to the sheet material without a scrap. The deformation process in the second stage for Dpr = 5.8 mm is shown in Fig.8. When Ps2 was 0.5 mm, a chip was not formed because the diameter of the punch in the first stage was equal to the diameter of the protrusion in the second stage. The cutting edge of the die bit into the sheet material on the die. When Ps2 was 1.0 mm, the separation process between the die edge and protrusion was continued. From the above results, it is expected that a chip and scrap will be connected by shortening the length of the protrusion from 1.0 mm. (a)
(b)
(c)
Chip
Fig. 7. Deformation process in second stage for Dpr =5.0mm and Lpr=1.0 mm; (a) Ps2=0.5 mm; (b) Ps2=1.0 mm; (c) Ps2=1.5 mm. (a)
(b)
(c)
Fig. 8. Deformation process in the second stage for Dpr =5.8 mm and Lpr=1.0 mm; (a) Ps2=0.5 mm; (b) Ps2=1.0 mm; (c) Ps2=1.5 mm.
Masahiro Sasada et al. / Procedia Manufacturing 15 (2018) 653–659 Author name / Procedia Manufacturing 00 (2018) 000–000
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3.2. Effect of length of protrusion Piercing using the protrusion punch with Dpr = 5.8 mm and Lpr = 0.3 mm was carried out. The cross sectional view of the hole and scrap after the second stage are shown in Fig. 9. There is a crack in part of the joint between the chip and scrap, but the chip was connected to the scrap under the punch after the second stage. The relationship between the length of the fractured surface and Lpr is shown in Fig. 10. In the case of Lpr = 0.0 mm, piercing was carried out using the punch without the protrusion in the second stage. The length of the fractured surface for Lpr = 0.3 mm was smaller than that for Lpr = 0.0 mm, but longer than that for Lpr=1.0 mm, and the chip was not connected to the scrap when Lpr was 1.0 mm, as shown in Fig. 4. Therefore it is considered that the protrusion was effective in decreasing the length of the fractured surface. However, the length of the protrusion was decided so as not to separate the chip from the scrap. The deformation process in the second stage for Lpr = 0.3 mm is shown in Fig. 11. When Ps2 was 0.5 mm, the chip was formed by the protrusion tip, and the scrap was not pushed by the protrusion. When Ps2 was 1.0 mm, the scrap was pushed via the chip formed by the protrusion. The cutting edge of die bit into the sheet material on the die. When Ps2 was 1.5 mm, separation between the die edge and the protrusion did not occur. Thus, it is considered that separation between the punch edge and the die edge occurred. Fig. 9(b) indicates that separation between the punch edge and die edge occurred. (a)
(b)
Fig. 9. (a) Hole and chip and (b) scrap for Dpr = 5.8 mm and Lpr = 0.3 mm.
Length of fractured surface (mm)
1
0.8
0.6
0.4
0.2
0
0
0.2
0.4
0.6
0.8
1
1.2
Legth of protrusion Lpr (mm)
Fig. 10. Relationship between length of fractured surface and diameter of protrusion for Dpr = 5.8 mm. (a)
(b)
(c)
Fig. 11. Deformation process in second stage for Dpr =5.8 mm and Lpr=0.3 mm; (a) Ps2 = 0.5 mm; (b) Ps2 = 1.0 mm; (c) Ps2 = 1.5 mm.
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Masahiro Sasada et al. / Procedia Manufacturing 15 (2018) 653–659 Author name / Procedia Manufacturing 00 (2018) 000–000
3.3. Constitution of cut surface The constitution of the cut surface is shown in Fig. 12. In this figure, piercing refers to conventional piercing, shaving indicates press shaving and Lpr refers to piercing after half punching when the diameter of the protrusion was 5.8 mm. The length of burnished surface obtained by piercing with the protrusion punch for Lpr = 1.0 mm was the longest in these experimental conditions. But the chip was not connected to scrap under the punch as shown in Figure 4. When the chip was connected to the scrap, the length of burnished surface for Lpr = 0.3 mm was the longest in these experimental conditions. The length of the burnished surface for Lpr = 0.3 mm was longer than that for conventional piercing. When the diameter of the protrusion was 5.8 mm and its height was 0.3 mm, the burnished surface after the second stage had a length of about 1.66 mm. The length of the burnished surface reached 83% of the sheet thickness even though Ps1 was only 70% of the sheet thickness. In this case, the chip was connected to the sheet material under the punch after the second stage. The use of a protrusion punch was effective in increasing the length of the burnished surface with the chip connected to the scrap. The discussions about the optimum shape of protrusion and the shape of hole are considered necessary in the future. Shear droop Burnished surface Fractured surface Burr
Constitution of cut surface (mm)
2.5 2 1.5 1 0.5 0 -0.5 -1
Piercing Shaving Lpr 0.0 Lpr 0.3 Lpr 1.0
Fig. 12. Constitution of cut surface.
4. Conclusion To extend the burnished surface of a cutting surface with the chip connected to the scrap under the punch, piercing using a protrusion punch after half punching was carried out. The effect of the protrusion on the cutting surface and chip was investigated. The results obtained in this study were as follows: (1) When the length of the protrusion (Lpr) was 1.0 mm, the chip was not connected to the scrap regardless of the diameter of the protrusion (Dpr), which was 5.0, 5.5 or 5.8 mm. The length of the fractured surface decreased with increasing Dpr. (2) The length of the burnished surface for Dpr = 5.8 mm and Lpr = 0.3 mm was longer than that for conventional piercing. In this case, there was a crack in part of the joint between the chip and the sheet material under the punch, but the chip was connected to the sheet material under the punch after second stage. The use of a protrusion punch was effective in increasing the length of the burnished surface with the chip connected to the scrap. However, the length of the protrusion was decided so as not to separate the chip from the scrap. Acknowledgements The authors would like to thank Mr. K. Kitamura, Mr. S. Furugen, Mr. S. Nagano, Mr. K. Furuta and Mr. K. Ikeda for their help in this study.
Masahiro Sasada et al. / Procedia Manufacturing 15 (2018) 653–659 Author name / Procedia Manufacturing 00 (2018) 000–000
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References [1] M. Murakawa, S. Thipprakmas, M. Jin, Investigation of the relashionship between shaved surface and shaving allowance, Journal of the Japan society for technology of plasticity, 44-513 (2003) 1049–1053. [2] H. Hoffman, F. Hormann, Improving the cur edge by counter-shaving, Key Engineering Materials, 344 (2007) 217–224. [3] K. Nakamura, M. Yokai, A study of shaving press process, Journal of the Japan Society for Technology of Plasticity, 4-29 (1963) 387–395. [4] M. Sasada, Y. Kamiichi, T. Kikuchi, Influence of the punch penetration depth in half punching on the cut edge after shaving, Key Engineering Materials, 622-623 (2014) 1081–1086.
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Procedia Manufacturing 15 (2018) 653–659 Procedia Manufacturing 00 (2017) 000–000 www.elsevier.com/locate/procedia
17th International Conference on Metal Forming, Metal Forming 2018, 16-19 September 2018, 17th International Conference on MetalToyohashi, Forming, Metal Japan Forming 2018, 16-19 September 2018, Toyohashi, Japan
Effect of use of protrusion punch on length of burnished surface in Effect of useEngineering of protrusion punch onConference length of burnished surface in Manufacturing Society International 2017, MESIC 2017, 28-30 June piercing after half punching 2017, Vigo (Pontevedra), Spain piercing after half punching Masahiro Sasada*, Syuu Katou Costing models for capacity in Industry 4.0: Trade-off Masahirooptimization Sasada*, Syuu Katou Department of Mechanical Engineering, Kanagawa University, Rokkakubashi 3-27-1, Kanagawa-ku, Yokohama, Kanagawa,221-8686, Japan between used capacity and operational Department of Mechanical Engineering, Kanagawa University, Rokkakubashi 3-27-1, Kanagawa-ku, efficiency Yokohama, Kanagawa,221-8686, Japan
Abstract A. Santanaa, P. Afonsoa,*, A. Zaninb, R. Wernkeb Abstract a Shearing is a cutting method with high productivity. The cut4800-058 surfaceGuimarães, consists ofPortugal a shear droop, a burnished surface, a fractured University of Minho, Shearingand is aburr. cutting high productivity. The89809-000 cutfractured surface consists of a shear droop, obtained a burnished surface, atofractured surface Pressmethod shavingwith removes thebshear droop and surface the cut surface by shearing increase Unochapecó, Chapecó, SC,on Brazil surface andof burr. shaving removes shear droop the and trimming fractured surface on the cut to surface obtained shearing to of increase the length thePress burnished surface. In the press shaving, allowance is set a small value.by The amount chips the length of the burnished surface. In press shaving, the trimming allowance is set to a small value. The amount of chips obtained by press shaving is very small. The occurrence of small chips is a problem for press working. Therefore, it is desirable obtained byburnished press shaving is very small. The occurrence of smallof chips is chips. a problem forpiercing press working. Therefore, it isallowance desirable that a large surface is obtained without the occurrence small When with a small trimming Abstract that apreviously large burnished is obtained without the occurrence of small chips. piercing small However, trimming allowance was carriedsurface out after half punching, a chip was connected to the sheetWhen material underwith the apunch. the length was previously after half punching, chip was connected the sheet material underhalf the punching punch. However, the length of the burnishedcarried surfaceoutwas decreased. In thisastudy, piercing using to a protrusion punch after was carried out to of the burnished surface was decreased. In this study, piercing using a protrusion punch after half punching was carried out to Under the concept of "Industry 4.0", production processes will be pushed to be increasingly interconnected, increase the length of the burnished surface. The effect of the use of a protrusion punch on the length of the burnished surface increase the length burnished Thenecessarily, effect of the much use of more a protrusion punch on the length of the burnished surface information based ontheawas realinvestigated. time surface. basis and, efficient. In this context, capacity optimization and the shape of theof chip and the shape of chip was investigated. goes beyond thethe traditional aim of capacity maximization, contributing also for organization’s profitability and value. © 2018 The Authors. Publishedand by Elsevier B.V. improvement approaches suggest capacity optimization instead of Indeed, lean management continuous © 2018 2018 The The Authors. Authors. Published Published by by Elsevier Elsevier B.V. © B.V. Peer-review under responsibility of the scientific committee ofcosting the 17th 17thmodels International Conference on MetalForming. Forming. maximization. The study of capacity optimization andof is anConference importanton research topic that deserves Peer-review under responsibility of the scientific committee the International Metal Peer-review under responsibility of the scientific committee of the 17th International Conference on Metal Forming.
contributions from both the practical and theoretical perspectives. This paper presents and discusses a mathematical Keywords: Shaearing, Protrusin punch, Chip, Burnished surface, Half punching model for capacity management based on different costing models (ABC and TDABC). A generic model has been Keywords: Shaearing, Protrusin punch, Chip, Burnished surface, Half punching developed and it was used to analyze idle capacity and to design strategies towards the maximization of organization’s value. The trade-off capacity maximization vs operational efficiency is highlighted and it is shown that capacity 1. Introduction optimization might hide operational inefficiency. 1. Introduction © 2017 The Authors. Published by Elsevier B.V. Shearing is a cutting method with high productivity. The cut surface consists of a shear droop, a burnished surface, Peer-review responsibility of with the scientific committee ofThe the Manufacturing Engineering Society International Conference Shearingunder is a cutting high productivity. cut surface consists of a shear droop, a burnished surface, a2017. fractured surface and method burr. Press shaving removes the droop and fractured surface on the cut surface obtained by a fractured Press shaving removes the droop fractured surface on the cut surface obtained shearing to surface increaseand theburr. length of the burnished surface. Pressand shaving consists of two stages. The first stage isbya shearing to increase the length of the burnished surface. Press shaving consists of two stages. The first stage is a Keywords: Cost Models; ABC; TDABC; Capacity Management; Idle Capacity; Operational Efficiency 1. Introduction
* Corresponding author. Present address: Doshisha University, Kyotanabe, Kyoto, 610-0394, JAPAN Tel.: +81-774-65-6556. * E-mail Corresponding Present address: Doshisha University, Kyotanabe, Kyoto, 610-0394, JAPAN Tel.: +81-774-65-6556. address:author. [email protected] The cost of idle capacity is a fundamental information for companies and their management of extreme importance E-mail address: [email protected]
in modern©production systems. In general, it isB.V. defined as unused capacity or production potential and can be measured 2351-9789 2018 The Authors. Published by Elsevier 2351-9789 2018 Authors. Published Elsevier B.V.hours of the Peer-review underThe responsibility of theby scientific committee 17th International on Metal Forming. in several©ways: tons of production, available manufacturing, etc.Conference The management of the idle capacity Peer-review under responsibility thefax: scientific committee * Paulo Afonso. Tel.: +351 253 510of 761; +351 253 604 741 of the 17th International Conference on Metal Forming. E-mail address: [email protected]
2351-9789 © 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the scientific committee of the Manufacturing Engineering Society International Conference 2017. 2351-9789 © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the scientific committee of the 17th International Conference on Metal Forming. 10.1016/j.promfg.2018.07.291
Masahiro Sasada et al. / Procedia Manufacturing 15 (2018) 653–659 Author name / Procedia Manufacturing 00 (2018) 000–000
654 2
blanking or punching stage and the second stage is a shaving stage. The relationship between several press shaving characteristics and the shaving allowance has been investigated by an experiment and FEM [1]. Improving the cut edge by counter-shaving has been investigated [2]. The shaving of stacked sheet materials has been carried out to reduce the area of the fractured surface [3]. These useful researches have been reported. In the shaving stage, the trimming allowance is set to a small value. Therefore, the amount of chips obtained by press shaving is very small. The occurrence of small chips is a problem for press working. It is desirable that a large burnished surface is obtained without the occurrence of small chips. When piercing with a small trimming allowance was carried out after half punching, a chip was connected to the sheet material under the punch [4]. However, the length of the burnished surface was decreased. In this study, piercing using a protrusion punch after half punching was carried out to increase the length of the burnished surface. The effect of the use of a protrusion punch on the length of the burnished surface and the shape of chip was investigated. 2. Experimental method Experiments consisted of two stages. In the first stage, half punching with a negative clearance was carried out, and in the second stage, piercing using a protrusion punch was carried out. The experimental equipment is shown in Fig. 1(a). An aluminum (JIS A1100P-O) sheet with a length and width of 40 mm and a thickness of 2 mm was used. The blank holding force was set to 2370 N. A paraffin-type base oil (kinematic viscosity 90×10-6 m2/s) was applied to both surface of the sheet material before starting the punching. The punch displacement was measured using linear position sensors mounted on the dieset. The punching speed was set to 0.1 mm/s. In the first stage, half punching with a negative clearance was carried out, where the diameter of the punch was 5.8 mm and the clearance was set to -5% of the sheet material thickness. The punch penetration depth (Ps1) was set to 1.4 mm. In the second stage, piercing using a protrusion punch was carried out. An illustration of the protrusion punch is shown in Fig. 1(b). The diameter of the punch was 6 mm, the diameter of the protrusion (Dpr) was set to 5.0, 5.5 or 5.8 mm and the length of the protrusion (Lpr) was set to 0.3 or 1.0 mm. The clearance was set to 5% of the sheet thickness. Conventional punching was also carried out with the diameter set to 6.0 mm. In addition, conventional press shaving was carried out, where the clearance was 5.0% and the trimming allowance was 5%. The diameter of the punch was also set to 6.0 mm for the shaving stage. The experiment was conducted three times for each experimental condition. Then the lengths of shear droop, burnished surface, fractured surface and burr were measured from photographs of cross sectional view. (a)
(b) Load cell
Pilot pin
Displacement sensor Blank holder Lpr
Punch
Die Dpr
Fig. 1. (a) Experimental apparatus for first and second stages and (b) protrusion punch.
3. Experimental results 3.1. Holes and scraps for Lpr =1.0 mm The cross sectional views of the hole and scrap obtained by punching using the protrusion punch with Dpr = 5.0 mm and Lpr = 1.0 mm are shown in Fig. 2. The chip obtained in the second stage was not connected to the scrap
Masahiro Sasada et al. / Procedia Manufacturing 15 (2018) 653–659 Author name / Procedia Manufacturing 00 (2018) 000–000
655 3
under the punch. Cross sectional view of the hole and scrap obtained by punching using the protrusion punch with Dpr = 5.5 mm are shown in Fig. 3. Cross sectional views of hole and scrap obtained by punching using the protrusion punch with Dpr = 5.8 mm are also shown in Fig. 4. The chip was not connected to the scrap regardless of Dpr. However, the length of the burnished surface increased with increasing Dpr. The length of the fractured surface on the hole is shown in Fig. 5. In the case of Dpr = 0.0 mm, piercing using the punch without the protrusion was carried out in the second stage. Cross sectional view of the hole and scrap obtained by piercing after half punching are shown in Fig. 6. When Dpr was 0.0 mm, the length of the fractured surface was larger than the length of the remaining thickness (0.6 mm) after the first stage. The length of the fractured surface was smaller than the length of the remaining thickness after the first stage in the cases of Dpr = 5.5 and 5.8 mm. (a)
(b)
(c)
Fig. 2. (a) Hole, (b) scrap and (c) chip for Dpr = 5.0 mm and Lpr = 1.0 mm. (a)
(b)
(c)
Fig. 3. (a) Hole, (b) scrap and (c) chip for Dpr = 5.5 mm and Lpr = 1.0 mm. (a)
(b)
Fig. 4. (a) Hole and chip and (b) scrap for Dpr = 5.8 mm and Lpr = 1.0 mm.
Masahiro Sasada et al. / Procedia Manufacturing 15 (2018) 653–659 Author name / Procedia Manufacturing 00 (2018) 000–000
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Length of fractured surface (mm)
1
0.8
0.6
0.4
0.2
0
0
1 2 3 4 5 Diameter of protrusion Dpr (mm)
6
Fig. 5. Relationship between length of fractured surface and diameter of protrusion for Lpr =1.0 mm. (a)
(b)
Fig. 6. (a) Hole and chip and (b) scrap for Dpr = 0.0 mm.
The deformation process in the second stage for Dpr = 5.0 mm is shown in Fig. 7. For Ps2 = 0.5 mm, a chip was formed by the punch edge and the scrap was pushed by the protrusion. When Ps2 was 1.0 mm, the scrap was separated from the sheet material on the die by the protrusion. When Ps2 was 1.5 mm, the piercing continued to the sheet material without a scrap. The deformation process in the second stage for Dpr = 5.8 mm is shown in Fig.8. When Ps2 was 0.5 mm, a chip was not formed because the diameter of the punch in the first stage was equal to the diameter of the protrusion in the second stage. The cutting edge of the die bit into the sheet material on the die. When Ps2 was 1.0 mm, the separation process between the die edge and protrusion was continued. From the above results, it is expected that a chip and scrap will be connected by shortening the length of the protrusion from 1.0 mm. (a)
(b)
(c)
Chip
Fig. 7. Deformation process in second stage for Dpr =5.0mm and Lpr=1.0 mm; (a) Ps2=0.5 mm; (b) Ps2=1.0 mm; (c) Ps2=1.5 mm. (a)
(b)
(c)
Fig. 8. Deformation process in the second stage for Dpr =5.8 mm and Lpr=1.0 mm; (a) Ps2=0.5 mm; (b) Ps2=1.0 mm; (c) Ps2=1.5 mm.
Masahiro Sasada et al. / Procedia Manufacturing 15 (2018) 653–659 Author name / Procedia Manufacturing 00 (2018) 000–000
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3.2. Effect of length of protrusion Piercing using the protrusion punch with Dpr = 5.8 mm and Lpr = 0.3 mm was carried out. The cross sectional view of the hole and scrap after the second stage are shown in Fig. 9. There is a crack in part of the joint between the chip and scrap, but the chip was connected to the scrap under the punch after the second stage. The relationship between the length of the fractured surface and Lpr is shown in Fig. 10. In the case of Lpr = 0.0 mm, piercing was carried out using the punch without the protrusion in the second stage. The length of the fractured surface for Lpr = 0.3 mm was smaller than that for Lpr = 0.0 mm, but longer than that for Lpr=1.0 mm, and the chip was not connected to the scrap when Lpr was 1.0 mm, as shown in Fig. 4. Therefore it is considered that the protrusion was effective in decreasing the length of the fractured surface. However, the length of the protrusion was decided so as not to separate the chip from the scrap. The deformation process in the second stage for Lpr = 0.3 mm is shown in Fig. 11. When Ps2 was 0.5 mm, the chip was formed by the protrusion tip, and the scrap was not pushed by the protrusion. When Ps2 was 1.0 mm, the scrap was pushed via the chip formed by the protrusion. The cutting edge of die bit into the sheet material on the die. When Ps2 was 1.5 mm, separation between the die edge and the protrusion did not occur. Thus, it is considered that separation between the punch edge and the die edge occurred. Fig. 9(b) indicates that separation between the punch edge and die edge occurred. (a)
(b)
Fig. 9. (a) Hole and chip and (b) scrap for Dpr = 5.8 mm and Lpr = 0.3 mm.
Length of fractured surface (mm)
1
0.8
0.6
0.4
0.2
0
0
0.2
0.4
0.6
0.8
1
1.2
Legth of protrusion Lpr (mm)
Fig. 10. Relationship between length of fractured surface and diameter of protrusion for Dpr = 5.8 mm. (a)
(b)
(c)
Fig. 11. Deformation process in second stage for Dpr =5.8 mm and Lpr=0.3 mm; (a) Ps2 = 0.5 mm; (b) Ps2 = 1.0 mm; (c) Ps2 = 1.5 mm.
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Masahiro Sasada et al. / Procedia Manufacturing 15 (2018) 653–659 Author name / Procedia Manufacturing 00 (2018) 000–000
3.3. Constitution of cut surface The constitution of the cut surface is shown in Fig. 12. In this figure, piercing refers to conventional piercing, shaving indicates press shaving and Lpr refers to piercing after half punching when the diameter of the protrusion was 5.8 mm. The length of burnished surface obtained by piercing with the protrusion punch for Lpr = 1.0 mm was the longest in these experimental conditions. But the chip was not connected to scrap under the punch as shown in Figure 4. When the chip was connected to the scrap, the length of burnished surface for Lpr = 0.3 mm was the longest in these experimental conditions. The length of the burnished surface for Lpr = 0.3 mm was longer than that for conventional piercing. When the diameter of the protrusion was 5.8 mm and its height was 0.3 mm, the burnished surface after the second stage had a length of about 1.66 mm. The length of the burnished surface reached 83% of the sheet thickness even though Ps1 was only 70% of the sheet thickness. In this case, the chip was connected to the sheet material under the punch after the second stage. The use of a protrusion punch was effective in increasing the length of the burnished surface with the chip connected to the scrap. The discussions about the optimum shape of protrusion and the shape of hole are considered necessary in the future. Shear droop Burnished surface Fractured surface Burr
Constitution of cut surface (mm)
2.5 2 1.5 1 0.5 0 -0.5 -1
Piercing Shaving Lpr 0.0 Lpr 0.3 Lpr 1.0
Fig. 12. Constitution of cut surface.
4. Conclusion To extend the burnished surface of a cutting surface with the chip connected to the scrap under the punch, piercing using a protrusion punch after half punching was carried out. The effect of the protrusion on the cutting surface and chip was investigated. The results obtained in this study were as follows: (1) When the length of the protrusion (Lpr) was 1.0 mm, the chip was not connected to the scrap regardless of the diameter of the protrusion (Dpr), which was 5.0, 5.5 or 5.8 mm. The length of the fractured surface decreased with increasing Dpr. (2) The length of the burnished surface for Dpr = 5.8 mm and Lpr = 0.3 mm was longer than that for conventional piercing. In this case, there was a crack in part of the joint between the chip and the sheet material under the punch, but the chip was connected to the sheet material under the punch after second stage. The use of a protrusion punch was effective in increasing the length of the burnished surface with the chip connected to the scrap. However, the length of the protrusion was decided so as not to separate the chip from the scrap. Acknowledgements The authors would like to thank Mr. K. Kitamura, Mr. S. Furugen, Mr. S. Nagano, Mr. K. Furuta and Mr. K. Ikeda for their help in this study.
Masahiro Sasada et al. / Procedia Manufacturing 15 (2018) 653–659 Author name / Procedia Manufacturing 00 (2018) 000–000
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References [1] M. Murakawa, S. Thipprakmas, M. Jin, Investigation of the relashionship between shaved surface and shaving allowance, Journal of the Japan society for technology of plasticity, 44-513 (2003) 1049–1053. [2] H. Hoffman, F. Hormann, Improving the cur edge by counter-shaving, Key Engineering Materials, 344 (2007) 217–224. [3] K. Nakamura, M. Yokai, A study of shaving press process, Journal of the Japan Society for Technology of Plasticity, 4-29 (1963) 387–395. [4] M. Sasada, Y. Kamiichi, T. Kikuchi, Influence of the punch penetration depth in half punching on the cut edge after shaving, Key Engineering Materials, 622-623 (2014) 1081–1086.