- Email: [email protected]
Shearing process of copper alloy wire for metal zipper
Available online at www.sciencedirect.com Available online at www.sciencedirect.com
ScienceDirect ScienceDirect
Procedia Manufacturing 00 (2018) 000–000 Available online atatwww.sciencedirect.com Available www.sciencedirect.com Procedia online Manufacturing 00 (2018) 000–000
ScienceDirect ScienceDirect
www.elsevier.com/locate/procedia www.elsevier.com/locate/procedia
Procedia Manufacturing 15 (2018) 639–646 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
Shearing process of copper alloy wire for metal zipper
Shearing process of International copper alloy wire 2017, for metal Manufacturing Engineering Society Conference MESIC zipper 2017, 28-30 June a, a a 2017, Vigo (Pontevedra), Spain Chikako Hiromi *, Shigeru Tsuchida , Futoshi Kozato , Hiroko Mikadoa,
a, a a ChikakoShingo HiromiKawamura *, Shigerua, Tsuchida ,Kita Futoshi KozatoYoneyama , Hiroko bMikadoa, a Kazuhiko , Takeshi a b Shingo Kawamura , Kazuhiko Kitaa, Takeshi Yoneyama Costing models for capacity optimization in Industry 4.0: Trade-off a YKK CORPORATION, 200, Yoshida, Kurobe, Toyama, 938-8601, Japan a YKK CORPORATION, 200, Yoshida, Kurobe, Toyama,Kanazawa, 938-8601, Ishikawa Japan 920-1192, Japan School of Mechanical Engineering, Kanazawa University, Kakuma-machi, b School of Mechanical Engineering, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan b
between used capacity and operational efficiency A. Santanaa, P. Afonsoa,*, A. Zaninb, R. Wernkeb
Abstract a University of Minho, 4800-058 Guimarães, Portugal Abstract b Unochapecó, 89809-000 Chapecó, SC,preformed Brazil Metal zipper elements are formed by shearing, forging, and bending from wires. These plastic deformations are Metal zipper elements are formed by shearing, forging, and bending from preformed wires. mechanisms These plasticin deformations carried out repeatedly and continuously at high speeds. This study investigated the deformation the shearing ofarea carried out repeatedly and continuously at high speeds. This study investigated the deformation mechanisms in the shearing of a round wire and a preformed wire. From the observation of the cross section of the wire during the shearing, it has been round wire that and shearing a preformed wire. From the wire observation of theofcross section of the wire during shearing,specimen it has been understood process of the round is composed simple shearing, compression of the sheared and Abstract understood that shearing the preformed round wirewire is composed of simple shearing, compression of the sheared specimen and Shearing process process of of the has been also investigated through the observation of sheared specimen. final separation. final separation. Shearing process of the preformed wire has been also investigated through the observation of sheared specimen. Under the concept of "Industry 4.0", production processes will be pushed to be increasingly interconnected, © 2018 The Authors. Published by Elsevier B.V. © 2018 2018 The The Authors. Published by Elsevier B.V. information basedresponsibility on a real time basis and, much more efficient.Conference In this context, capacity optimization © Authors. Published by B.V. necessarily, Peer-review under of Elsevier the scientific scientific committeeof ofthe the17th 17thInternational InternationalConference onMetal MetalForming. Forming. Peer-review under responsibility of the committee on goes beyond the traditional aim of capacity maximization, contributing also for organization’s profitability Peer-review under responsibility of the scientific committee of the 17th International Conference on Metal Forming. and value.
Indeed, management improvement approaches suggest capacity optimization instead of Keywords:lean Shearing process; Roundand wire;continuous Preformed wire; Shearing strain rate Keywords: Shearing process; wire; Preformed wire; Shearing rate models is an important research topic that deserves maximization. The studyRound of capacity optimization and strain costing contributions from both the practical and theoretical perspectives. This paper presents and discusses a mathematical model for capacity management based on different costing models (ABC and TDABC). A generic model has been 1. Introduction 1. Introduction developed and it was used to analyze idle capacity and to design strategies towards the maximization of organization’s Metal elements used in items such as pants, bags, and shoes are manufactured throughthat thecapacity plastic value. Thezipper trade-off capacity maximization vs operational efficiency is highlighted and it is shown Metal zipper elements used in inefficiency. items suchofascopper pants,zinc bags, andusing shoes are manufactured the plastic deformation of Y-shaped preformed wire made alloy a chain machine. First,through the preformed wire optimization might hide operational deformation of Y-shaped made of copper zinc alloy using machine. First,two the legs preformed is sheared a small chip.preformed Then the wire chip is forged to make a concave anda achain protrusion. Finally in the wire chip © 2017 The to Authors. Published by Elsevier B.V. is a small chip.for Then thescientific chip 1). is committee forged to of make aisconcave andEngineering a protrusion. Finally two legsdeformation in the chip Peer-review under responsibility of the the Manufacturing Society International Conference aresheared bent toto cramp a tape zipper (Fig. A zipper chain manufactured by repeating these plastic are to cramp aattape forspeeds. zipper However, (Fig. 1). Ainzipper chain manufactured repeating these plastic deformation 2017. stepsbent continuously high the case of isnewly designed by zippers, deformation for the designed steps continuously at high speeds. However, in the case of newly designed zippers, deformation for the designed form is so difficult that it takes a certain amount of trial and error to form the target shape. Therefore, accelerating Keywords: Cost Models; that ABC;itTDABC; Capacity; Operational Efficiency form is so difficult takes aCapacity certainManagement; amount ofIdle trial and error to form the target shape. Therefore, accelerating 1. Introduction
* Corresponding author. Tel.: +81-765-8704; fax: +81-765-54-8775. * E-mail Corresponding Tel.: +81-765-8704; fax: +81-765-54-8775. 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.2018.07.289
Chikako Hiromi et al. / Procedia Manufacturing 15 (2018) 639–646 Author name / Procedia Manufacturing 00 (2018) 000–000
640 2
the development of these processes is a high priority. In this report, we focused on the first step, namely the shearing process, aiming to clarify the deformation mechanism in the shearing of the preformed wire. Many studies have been performed on the shearing process [1-4]; for instance, the influence of clearance on shear surface characteristics was investigated by an experiment using carbon steel wires. However, few studies have been conducted on copper alloys. And there have been no report on the shearing mechanism of a preformed wire for metal zipper. Therefore we planned the two steps to investigate the shearing of metal zipper wire. As the first step, shearing of a round wire of copper-zinc alloy was investigated to elucidate basic mechanism. As the second step, the shearing of preformed wire was observed and inspected.
Preformed wire
Plastic deformation by chain machine
Fastener chain
Processing direction
Shearing
Forging
Attaching(Bending)
Fig. 1. Plastic deformation of metal zipper elements.
2. Materials and methods 2.1. Materials Test materials included round and preformed wires made of copper-zinc alloy equivalent to H01 C23000. The round wire was 1.5 mm in diameter with an area of 1.77 mm2. The preformed wire was 2.8 mm in height, 3.3 mm in width, and 3.84 mm2 in area. Table 1 shows the mechanical properties of the test materials; the tensile strength of the wire was carried out under 0.8×10-2 s-1, and the average hardness on the cross section was obtained. Table 1. Mechanical properties of wire. Round wire
Preformed wire
Height 2.8 mm
Wire shape φ 1.5 mm Area 1.77 mm2
Tensile strength / MPa
680
Area 3.84 mm2 Width 3.3 mm
600
Elongation / %
2
3
Hardness / HV
188
184
Chikako Hiromi et al. / Procedia Manufacturing 15 (2018) 639–646 Author name / Procedia Manufacturing 00 (2018) 000–000
641 3
2.2. Experimental device A schematic illustration of the experimental device used in this study is shown in Fig. 2. The test conditions are shown in Table 2. The top part (0.9 mm in length) of the wire is protruded above the top surface of the die. A punch pushes the protruded wire over the die hole to shear the wire. This process is repeated continuously automatically. The experimental device, the chain machine, is driven by a cam mechanism, and the shearing speed is followed in the cam stroke motion. The shearing speed was defined as the average speed provided from a cam curve. Definitions of the names of the sheared surfaces are shown in Fig. 3 as follows: the plane on the die side (upper shear surface), which is the die shear surface, and the plane cut off by the punch (lower shear surface), which is the punch shear surface.
Punch(Fix) Specimen
Die
A
Punch (Fix)
Clearance
Die
Load cell Cu-Zn alloy wire
Shearing speed
Fig. 2. Schematic drawing of shearing machine (chain machine).
Table 2. Test conditions. Wire feed / mm
0.9
Shearing speed / mm/s
1, 75, 740, 1490
Clearance / mm
0.04
Punch (Fix)
Sheared surface in die side
Die
Shearing direction
Sheared surface in punch side
Fig. 3. Definition of sheared surface.
642 4
Chikako Hiromi et al. / Procedia Manufacturing 15 (2018) 639–646 Author name / Procedia Manufacturing 00 (2018) 000–000
2.3. Evaluation methods The shearing load was measured using a small compression load cell placed on the rear side of the punch, as shown in Fig. 2. The sheared surfaces of the specimens were observed by a scanning electron microscope. The shape of the sheared specimens were evaluated by creating a 3D model with X-ray CT. Furthermore, cross-sections of the sheared specimen were etched with potassium dichromate and the metal structures were observed with a microscope. 2.4. Definitions of shearing strain rate and true shearing stress The shearing strain rate was obtained by dividing the shearing speed by the clearance between the punch and the die. The true shearing stress was obtained by dividing the measured load by the un-separated area (Fig. 4) at the theoretical punch position obtained from the cam curve.
Punch side (Fix)
Punch side (Fix) Un-separated area Die side
Die side
Fig. 4. Definition of un-separated area and true shearing stress.
3. Results of the shearing of round wire 3.1. Dimensions of sheared specimens of round wires Geometric features of the sheared round wire are defined as shown in Fig. 5. The broken lines in the figure show the target shape. Table 3 shows deformation ratios (TF/T0 and HF /H0) and tilt angles for the sheared specimens. The influence of shearing strain rate on the ratio of height (HF), thickness (TF), and tilt angle were small.
Fig. 5. Definition of sheared surface (round wire).
5 643
Author name / Procedia Manufacturing 00 (2018) 000–000 Chikako Hiromi et al. / Procedia Manufacturing 15 (2018) 639–646
Table 3. Deformation rate and tilt angle of sheared specimens (round wire) . Shearing strain rate
Thickness
Height
Tilt angle
[s-1]
TF / T0 [%]
HF / H0 [%]
[deg.]
3
114
95
97
1.9×104
116
94
98
3.7×10
112
95
98
1.9×10
4
3.2. Metal structure (round wire vertical cross section) Metal structure images are shown in Fig. 6. At punch position (i), shearing was observed on the boundary line between the punch and the die. At punch position (ii), tilting of the sheared specimen, compression at the contacting surface with the punch and compressive deformation from that surface to the extruded bottom edge and shearing deformation around the area of A over the boundary between the sheared specimen and the remaining wire are observed. The cutting distance of the punch side (a) was larger than extruded distance (b). At punch position (iii), a crack was observed on the punch side. Punch position (ii)
Overall
Punch position (i)
A 200 µm
b
Punch position (iii)
a 200 µm
Crack 200 µm
Fig. 6. Images of metal structure at several punch positions (round wire).
3.3. Evaluation of round wire shearing stresses and shearing process of round wire The true shearing stress was calculated from the shearing load divided by the un-separated area. The bending stress was obtained from the moment by the load at the estimated acting position and un-separated cross shape using material strength equation. Both results are shown in Fig.7. The shearing yield stress and the maximum tensile stress of the material are also displayed in this figure. At punch position (i), the true shearing stress satisfies the yield condition, and the punch causes shearing. This observation is consistent with the sheared specimens obtained in Fig. 6 (i). Therefore, Fig. 8 shows the shearing model predicted for the punch position (i); shearing on the boundary line proceeds as shown in (a). Next, from the punch position (ii) to punch position (iii), the shearing stress satisfies the yield conditions similar to as in punch position (i); thus, shearing owing to the shear stress continues. In addition, there is an increase in the bending stress, and this observation is consistent with the observed deformation of the sheared specimens in Fig. 6 (ii). Further, compressive deformation occurs owing to the difference in cutting distance on the punch side and the die side. Therefore, Fig. 8(b) represents the shearing model of punch position (ii). The bending stress at punch position (iii) is higher than that at punch position (ii); this indicates that stress in the vertical direction increases. Near punch position (iii), there is a possibility of crack formation because the stress is
Chikako Hiromi et al. / Procedia Manufacturing 15 (2018) 639–646 Author name / Procedia Manufacturing 00 (2018) 000–000
644 6
the same as the maximum tensile stress of the material. This is consistent with the observation of cracks in Fig. 6(iii). Therefore, the shearing model of the punch position (iii) is as shown in Fig. 8(c).
True shearing stress Bending stress Punch position i
Punch position ii
Punch position iii
800 Maximum tensile stress
Stress / MPa
600 Shearing yield stress
400 200 0
0
0.2
0.4 0.6 Punch position
0.8
1
Fig. 7. Relationship between stresses and punch position.
Punch side (Fix)
Punch side (Fix)
a>b
Compressive deformation zone
Punch side (Fix)
a b
Die side
Die side
Sheraring direction
Shearing direction
(a) Punch position (i)
Compressive deformation zone
Die side Shearing direction
(b) Punch position (ii) (C) Punch position (iii) Fig. 8. Schemes of shearing mechanism (round wire).
4. Results of the shearing of preformed wire 4.1. Dimensions of sheared specimen of preformed wire Definitions of geometric features in the sheared specimen of the preformed wire is shown in Fig. 9. The broken lines in the figure show the target shape. Geometric features obtained in the shearing strain rates from 1.9×103 to 3.7 ×104 s-1 are shown in Table 4. The influence of shearing strain rate on the deformation of sheared specimen was small. These results are similar to the round wire results (as shown in Table 3).
7
Author name / Procedia Manufacturing 00 (2018) 000–000
Chikako Hiromi et al. / Procedia Manufacturing 15 (2018) 639–646
645
Fig. 9. Definition of sheared surface (preformed wire). Table 4. Deformation rate and tilt angle of sheared specimens (preformed wire). Shearing strain rate
Thickness
Height_A
Height_B
Tilt angle
[s ]
TF / T0 [%]
HF / H0 [%]
HF / H0 [%]
[deg.]
1.9×103
110
98
95
96
1.9×10
4
108
97
94
97
3.7×10
4
110
98
95
96
-1
4.2. Metal structure (preformed wire vertical cross section) Metal structure images are shown in Fig. 10. At punch position I, shearing was observed by the punch and the die. At punch position II, deformation was confirmed in the boundary area of the sheared specimen. The distance of the punch insertion (a) was larger than the distance of protrusion of the specimen material (b); this result is similar to that found for round wire. Metal flow with plastic deformation was observed in the sheared border. At punch position III, a crack was observed on the die side; this result differs from the round wire result. The final separation mechanism of the preformed wire will be examined in subsequent studies.
Punch position I
Punch position II
Punch position III
Overall
a
200 µm
Crack b
200 µm
Fig. 10. Images of metal structure at several punch positions (preformed wire).
200 µm
646 8
Chikako Hiromi et al. / Procedia Manufacturing 15 (2018) 639–646 Author name / Procedia Manufacturing 00 (2018) 000–000
5. Summary In this study, shearing was performed on round and preformed wires, and the deformation mechanisms in the shearing processes were examined. The following major conclusions are drawn from the results. 1. For both round and preformed wires, shearing strain rates between 1.9 ×103 and 3.7×104 s-1 caused only minor effects on the height, thickness, and tilt angle of the sheared specimens. 2. From stress curves calculated based on the shearing load, the shearing process of the round wire is composed as follows: Step I: The true shearing stress satisfied the yield condition, and the punch caused shearing. Step II: The shearing and bending stresses satisfied the yield stress, and the sheared specimen displayed plastic deformation. The specimens deformed along the direction of thickness. Step III: A crack began to appear on the punch side and combine with previous deformations. 3. The shearing deformation of the preformed wire has been also observed and the shearing process is investigated based on the shearing process of round wire. References [1] H. Kudo, K. Tamura, Experimental investigation on steel bar cropping - part1. test with conventional cutting tools, Journal of Materials Processing Technology, 5-43 (1964) 527–535. [2] H. Kudo, K. Tamura, Experimental investigation on steel bar cropping - part2 observation of initiation and propagation of crack, Journal of Materials Processing Technology, 6-48 (1965) 27–36. [3] H. Kudo, K. Tamura, Experimental investigation on steel bar cropping - part 3. tests using travelling cutter with grooved side surface, Journal of Materials Processing Technology, 6-50 (1965) 165–172. [4] N. Koga, T. Kudoh, M. Murakawa, An application of visioplasticity to the analysis of shearing phenomenon, Journal of Materials Processing Technology, 33-383 (1992) 1362–1367.
ScienceDirect ScienceDirect
Procedia Manufacturing 00 (2018) 000–000 Available online atatwww.sciencedirect.com Available www.sciencedirect.com Procedia online Manufacturing 00 (2018) 000–000
ScienceDirect ScienceDirect
www.elsevier.com/locate/procedia www.elsevier.com/locate/procedia
Procedia Manufacturing 15 (2018) 639–646 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
Shearing process of copper alloy wire for metal zipper
Shearing process of International copper alloy wire 2017, for metal Manufacturing Engineering Society Conference MESIC zipper 2017, 28-30 June a, a a 2017, Vigo (Pontevedra), Spain Chikako Hiromi *, Shigeru Tsuchida , Futoshi Kozato , Hiroko Mikadoa,
a, a a ChikakoShingo HiromiKawamura *, Shigerua, Tsuchida ,Kita Futoshi KozatoYoneyama , Hiroko bMikadoa, a Kazuhiko , Takeshi a b Shingo Kawamura , Kazuhiko Kitaa, Takeshi Yoneyama Costing models for capacity optimization in Industry 4.0: Trade-off a YKK CORPORATION, 200, Yoshida, Kurobe, Toyama, 938-8601, Japan a YKK CORPORATION, 200, Yoshida, Kurobe, Toyama,Kanazawa, 938-8601, Ishikawa Japan 920-1192, Japan School of Mechanical Engineering, Kanazawa University, Kakuma-machi, b School of Mechanical Engineering, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan b
between used capacity and operational efficiency A. Santanaa, P. Afonsoa,*, A. Zaninb, R. Wernkeb
Abstract a University of Minho, 4800-058 Guimarães, Portugal Abstract b Unochapecó, 89809-000 Chapecó, SC,preformed Brazil Metal zipper elements are formed by shearing, forging, and bending from wires. These plastic deformations are Metal zipper elements are formed by shearing, forging, and bending from preformed wires. mechanisms These plasticin deformations carried out repeatedly and continuously at high speeds. This study investigated the deformation the shearing ofarea carried out repeatedly and continuously at high speeds. This study investigated the deformation mechanisms in the shearing of a round wire and a preformed wire. From the observation of the cross section of the wire during the shearing, it has been round wire that and shearing a preformed wire. From the wire observation of theofcross section of the wire during shearing,specimen it has been understood process of the round is composed simple shearing, compression of the sheared and Abstract understood that shearing the preformed round wirewire is composed of simple shearing, compression of the sheared specimen and Shearing process process of of the has been also investigated through the observation of sheared specimen. final separation. final separation. Shearing process of the preformed wire has been also investigated through the observation of sheared specimen. Under the concept of "Industry 4.0", production processes will be pushed to be increasingly interconnected, © 2018 The Authors. Published by Elsevier B.V. © 2018 2018 The The Authors. Published by Elsevier B.V. information basedresponsibility on a real time basis and, much more efficient.Conference In this context, capacity optimization © Authors. Published by B.V. necessarily, Peer-review under of Elsevier the scientific scientific committeeof ofthe the17th 17thInternational InternationalConference onMetal MetalForming. Forming. Peer-review under responsibility of the committee on goes beyond the traditional aim of capacity maximization, contributing also for organization’s profitability Peer-review under responsibility of the scientific committee of the 17th International Conference on Metal Forming. and value.
Indeed, management improvement approaches suggest capacity optimization instead of Keywords:lean Shearing process; Roundand wire;continuous Preformed wire; Shearing strain rate Keywords: Shearing process; wire; Preformed wire; Shearing rate models is an important research topic that deserves maximization. The studyRound of capacity optimization and strain costing contributions from both the practical and theoretical perspectives. This paper presents and discusses a mathematical model for capacity management based on different costing models (ABC and TDABC). A generic model has been 1. Introduction 1. Introduction developed and it was used to analyze idle capacity and to design strategies towards the maximization of organization’s Metal elements used in items such as pants, bags, and shoes are manufactured throughthat thecapacity plastic value. Thezipper trade-off capacity maximization vs operational efficiency is highlighted and it is shown Metal zipper elements used in inefficiency. items suchofascopper pants,zinc bags, andusing shoes are manufactured the plastic deformation of Y-shaped preformed wire made alloy a chain machine. First,through the preformed wire optimization might hide operational deformation of Y-shaped made of copper zinc alloy using machine. First,two the legs preformed is sheared a small chip.preformed Then the wire chip is forged to make a concave anda achain protrusion. Finally in the wire chip © 2017 The to Authors. Published by Elsevier B.V. is a small chip.for Then thescientific chip 1). is committee forged to of make aisconcave andEngineering a protrusion. Finally two legsdeformation in the chip Peer-review under responsibility of the the Manufacturing Society International Conference aresheared bent toto cramp a tape zipper (Fig. A zipper chain manufactured by repeating these plastic are to cramp aattape forspeeds. zipper However, (Fig. 1). Ainzipper chain manufactured repeating these plastic deformation 2017. stepsbent continuously high the case of isnewly designed by zippers, deformation for the designed steps continuously at high speeds. However, in the case of newly designed zippers, deformation for the designed form is so difficult that it takes a certain amount of trial and error to form the target shape. Therefore, accelerating Keywords: Cost Models; that ABC;itTDABC; Capacity; Operational Efficiency form is so difficult takes aCapacity certainManagement; amount ofIdle trial and error to form the target shape. Therefore, accelerating 1. Introduction
* Corresponding author. Tel.: +81-765-8704; fax: +81-765-54-8775. * E-mail Corresponding Tel.: +81-765-8704; fax: +81-765-54-8775. 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.2018.07.289
Chikako Hiromi et al. / Procedia Manufacturing 15 (2018) 639–646 Author name / Procedia Manufacturing 00 (2018) 000–000
640 2
the development of these processes is a high priority. In this report, we focused on the first step, namely the shearing process, aiming to clarify the deformation mechanism in the shearing of the preformed wire. Many studies have been performed on the shearing process [1-4]; for instance, the influence of clearance on shear surface characteristics was investigated by an experiment using carbon steel wires. However, few studies have been conducted on copper alloys. And there have been no report on the shearing mechanism of a preformed wire for metal zipper. Therefore we planned the two steps to investigate the shearing of metal zipper wire. As the first step, shearing of a round wire of copper-zinc alloy was investigated to elucidate basic mechanism. As the second step, the shearing of preformed wire was observed and inspected.
Preformed wire
Plastic deformation by chain machine
Fastener chain
Processing direction
Shearing
Forging
Attaching(Bending)
Fig. 1. Plastic deformation of metal zipper elements.
2. Materials and methods 2.1. Materials Test materials included round and preformed wires made of copper-zinc alloy equivalent to H01 C23000. The round wire was 1.5 mm in diameter with an area of 1.77 mm2. The preformed wire was 2.8 mm in height, 3.3 mm in width, and 3.84 mm2 in area. Table 1 shows the mechanical properties of the test materials; the tensile strength of the wire was carried out under 0.8×10-2 s-1, and the average hardness on the cross section was obtained. Table 1. Mechanical properties of wire. Round wire
Preformed wire
Height 2.8 mm
Wire shape φ 1.5 mm Area 1.77 mm2
Tensile strength / MPa
680
Area 3.84 mm2 Width 3.3 mm
600
Elongation / %
2
3
Hardness / HV
188
184
Chikako Hiromi et al. / Procedia Manufacturing 15 (2018) 639–646 Author name / Procedia Manufacturing 00 (2018) 000–000
641 3
2.2. Experimental device A schematic illustration of the experimental device used in this study is shown in Fig. 2. The test conditions are shown in Table 2. The top part (0.9 mm in length) of the wire is protruded above the top surface of the die. A punch pushes the protruded wire over the die hole to shear the wire. This process is repeated continuously automatically. The experimental device, the chain machine, is driven by a cam mechanism, and the shearing speed is followed in the cam stroke motion. The shearing speed was defined as the average speed provided from a cam curve. Definitions of the names of the sheared surfaces are shown in Fig. 3 as follows: the plane on the die side (upper shear surface), which is the die shear surface, and the plane cut off by the punch (lower shear surface), which is the punch shear surface.
Punch(Fix) Specimen
Die
A
Punch (Fix)
Clearance
Die
Load cell Cu-Zn alloy wire
Shearing speed
Fig. 2. Schematic drawing of shearing machine (chain machine).
Table 2. Test conditions. Wire feed / mm
0.9
Shearing speed / mm/s
1, 75, 740, 1490
Clearance / mm
0.04
Punch (Fix)
Sheared surface in die side
Die
Shearing direction
Sheared surface in punch side
Fig. 3. Definition of sheared surface.
642 4
Chikako Hiromi et al. / Procedia Manufacturing 15 (2018) 639–646 Author name / Procedia Manufacturing 00 (2018) 000–000
2.3. Evaluation methods The shearing load was measured using a small compression load cell placed on the rear side of the punch, as shown in Fig. 2. The sheared surfaces of the specimens were observed by a scanning electron microscope. The shape of the sheared specimens were evaluated by creating a 3D model with X-ray CT. Furthermore, cross-sections of the sheared specimen were etched with potassium dichromate and the metal structures were observed with a microscope. 2.4. Definitions of shearing strain rate and true shearing stress The shearing strain rate was obtained by dividing the shearing speed by the clearance between the punch and the die. The true shearing stress was obtained by dividing the measured load by the un-separated area (Fig. 4) at the theoretical punch position obtained from the cam curve.
Punch side (Fix)
Punch side (Fix) Un-separated area Die side
Die side
Fig. 4. Definition of un-separated area and true shearing stress.
3. Results of the shearing of round wire 3.1. Dimensions of sheared specimens of round wires Geometric features of the sheared round wire are defined as shown in Fig. 5. The broken lines in the figure show the target shape. Table 3 shows deformation ratios (TF/T0 and HF /H0) and tilt angles for the sheared specimens. The influence of shearing strain rate on the ratio of height (HF), thickness (TF), and tilt angle were small.
Fig. 5. Definition of sheared surface (round wire).
5 643
Author name / Procedia Manufacturing 00 (2018) 000–000 Chikako Hiromi et al. / Procedia Manufacturing 15 (2018) 639–646
Table 3. Deformation rate and tilt angle of sheared specimens (round wire) . Shearing strain rate
Thickness
Height
Tilt angle
[s-1]
TF / T0 [%]
HF / H0 [%]
[deg.]
3
114
95
97
1.9×104
116
94
98
3.7×10
112
95
98
1.9×10
4
3.2. Metal structure (round wire vertical cross section) Metal structure images are shown in Fig. 6. At punch position (i), shearing was observed on the boundary line between the punch and the die. At punch position (ii), tilting of the sheared specimen, compression at the contacting surface with the punch and compressive deformation from that surface to the extruded bottom edge and shearing deformation around the area of A over the boundary between the sheared specimen and the remaining wire are observed. The cutting distance of the punch side (a) was larger than extruded distance (b). At punch position (iii), a crack was observed on the punch side. Punch position (ii)
Overall
Punch position (i)
A 200 µm
b
Punch position (iii)
a 200 µm
Crack 200 µm
Fig. 6. Images of metal structure at several punch positions (round wire).
3.3. Evaluation of round wire shearing stresses and shearing process of round wire The true shearing stress was calculated from the shearing load divided by the un-separated area. The bending stress was obtained from the moment by the load at the estimated acting position and un-separated cross shape using material strength equation. Both results are shown in Fig.7. The shearing yield stress and the maximum tensile stress of the material are also displayed in this figure. At punch position (i), the true shearing stress satisfies the yield condition, and the punch causes shearing. This observation is consistent with the sheared specimens obtained in Fig. 6 (i). Therefore, Fig. 8 shows the shearing model predicted for the punch position (i); shearing on the boundary line proceeds as shown in (a). Next, from the punch position (ii) to punch position (iii), the shearing stress satisfies the yield conditions similar to as in punch position (i); thus, shearing owing to the shear stress continues. In addition, there is an increase in the bending stress, and this observation is consistent with the observed deformation of the sheared specimens in Fig. 6 (ii). Further, compressive deformation occurs owing to the difference in cutting distance on the punch side and the die side. Therefore, Fig. 8(b) represents the shearing model of punch position (ii). The bending stress at punch position (iii) is higher than that at punch position (ii); this indicates that stress in the vertical direction increases. Near punch position (iii), there is a possibility of crack formation because the stress is
Chikako Hiromi et al. / Procedia Manufacturing 15 (2018) 639–646 Author name / Procedia Manufacturing 00 (2018) 000–000
644 6
the same as the maximum tensile stress of the material. This is consistent with the observation of cracks in Fig. 6(iii). Therefore, the shearing model of the punch position (iii) is as shown in Fig. 8(c).
True shearing stress Bending stress Punch position i
Punch position ii
Punch position iii
800 Maximum tensile stress
Stress / MPa
600 Shearing yield stress
400 200 0
0
0.2
0.4 0.6 Punch position
0.8
1
Fig. 7. Relationship between stresses and punch position.
Punch side (Fix)
Punch side (Fix)
a>b
Compressive deformation zone
Punch side (Fix)
a b
Die side
Die side
Sheraring direction
Shearing direction
(a) Punch position (i)
Compressive deformation zone
Die side Shearing direction
(b) Punch position (ii) (C) Punch position (iii) Fig. 8. Schemes of shearing mechanism (round wire).
4. Results of the shearing of preformed wire 4.1. Dimensions of sheared specimen of preformed wire Definitions of geometric features in the sheared specimen of the preformed wire is shown in Fig. 9. The broken lines in the figure show the target shape. Geometric features obtained in the shearing strain rates from 1.9×103 to 3.7 ×104 s-1 are shown in Table 4. The influence of shearing strain rate on the deformation of sheared specimen was small. These results are similar to the round wire results (as shown in Table 3).
7
Author name / Procedia Manufacturing 00 (2018) 000–000
Chikako Hiromi et al. / Procedia Manufacturing 15 (2018) 639–646
645
Fig. 9. Definition of sheared surface (preformed wire). Table 4. Deformation rate and tilt angle of sheared specimens (preformed wire). Shearing strain rate
Thickness
Height_A
Height_B
Tilt angle
[s ]
TF / T0 [%]
HF / H0 [%]
HF / H0 [%]
[deg.]
1.9×103
110
98
95
96
1.9×10
4
108
97
94
97
3.7×10
4
110
98
95
96
-1
4.2. Metal structure (preformed wire vertical cross section) Metal structure images are shown in Fig. 10. At punch position I, shearing was observed by the punch and the die. At punch position II, deformation was confirmed in the boundary area of the sheared specimen. The distance of the punch insertion (a) was larger than the distance of protrusion of the specimen material (b); this result is similar to that found for round wire. Metal flow with plastic deformation was observed in the sheared border. At punch position III, a crack was observed on the die side; this result differs from the round wire result. The final separation mechanism of the preformed wire will be examined in subsequent studies.
Punch position I
Punch position II
Punch position III
Overall
a
200 µm
Crack b
200 µm
Fig. 10. Images of metal structure at several punch positions (preformed wire).
200 µm
646 8
Chikako Hiromi et al. / Procedia Manufacturing 15 (2018) 639–646 Author name / Procedia Manufacturing 00 (2018) 000–000
5. Summary In this study, shearing was performed on round and preformed wires, and the deformation mechanisms in the shearing processes were examined. The following major conclusions are drawn from the results. 1. For both round and preformed wires, shearing strain rates between 1.9 ×103 and 3.7×104 s-1 caused only minor effects on the height, thickness, and tilt angle of the sheared specimens. 2. From stress curves calculated based on the shearing load, the shearing process of the round wire is composed as follows: Step I: The true shearing stress satisfied the yield condition, and the punch caused shearing. Step II: The shearing and bending stresses satisfied the yield stress, and the sheared specimen displayed plastic deformation. The specimens deformed along the direction of thickness. Step III: A crack began to appear on the punch side and combine with previous deformations. 3. The shearing deformation of the preformed wire has been also observed and the shearing process is investigated based on the shearing process of round wire. References [1] H. Kudo, K. Tamura, Experimental investigation on steel bar cropping - part1. test with conventional cutting tools, Journal of Materials Processing Technology, 5-43 (1964) 527–535. [2] H. Kudo, K. Tamura, Experimental investigation on steel bar cropping - part2 observation of initiation and propagation of crack, Journal of Materials Processing Technology, 6-48 (1965) 27–36. [3] H. Kudo, K. Tamura, Experimental investigation on steel bar cropping - part 3. tests using travelling cutter with grooved side surface, Journal of Materials Processing Technology, 6-50 (1965) 165–172. [4] N. Koga, T. Kudoh, M. Murakawa, An application of visioplasticity to the analysis of shearing phenomenon, Journal of Materials Processing Technology, 33-383 (1992) 1362–1367.