control systems with on-delay timer Experimental analysis of electro-pneumatic optimization of hot stampingmachine Technology Journal of Applied Researchand

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Availableonlineatwww.sciencedirect.com

Journal of Applied Research and Technology

www.jart.ccadet.unam.mx JournalofAppliedResearchandTechnology15(2017)356–364

Original

Experimental analysis of electro-pneumatic optimization of hot stamping machine control systems with on-delay timer

Bankole I. Oladapo

^∗

, Vincent A. Balogun, Adeyinka O.M. Adeoye, Ige E. Olubunmi, Samuel O. Afolabi

DepartmentofMechanicalandMechatronicsEngineering,AfeBabalolaUniversity,Ado-Ekiti,Nigeria Received31July2016;accepted6March2017

Availableonline24August2017

Abstract

Thesustainabilitycriterioninthemanufacturingindustriesisimperative,especiallyintheautomobileindustries.Currently,effortsarebeing madebytheindustriestomitigateCO2emissionbythetotalvehicleweightoptimization,machineutilizationandresourceefficiency.Inlieuofthis, itisimportanttounderstudythemanufacturingmachinesadoptedintheautomobileindustries.Oneofsuchmachineisthehotstampingmachine thatisusedforabout35%ofthemanufacturingoperationswithintheautomobileindustries.Therefore,thestandardizationandoptimizationof thehotstampingprocesscouldreducethecarbonfootprintwithintheautomobileindustries.Thisworkunderstudiedtheon-delaytimerfunctional valveofthehotstampingmachineinordertodeterminevariousprocessparametersaffectingit.Thedetailedphysicalmodelofthepneumatic andelectro-pneumaticcylindersystemsforthecontrolissimulatedandoptimizedforboththepneumaticandelectro-pneumaticcylindersystems.

ExperimentalandsimulationmodelwereestablishedattheFESTOworkstationandFESTOFluidSIM^®5.1respectivelytoevaluatetheeffective velocity,accelerations,displacement,andflowrateforthepneumaticandelectro-pneumaticactuatoronbothsystems.Comparisonsweremade betweenpneumaticandelectro-pneumaticcylindersystemsontheircharacteristiccurveinordertooptimizetheprocessvariables.Theresultfavours theelectro-pneumaticcylindersystemsinstabilityandindesigninghotstampingmachines.Theresultobtainedcouldelucidatetheunderstanding ofthepressingarmofahotstampingmachine.

Keywords: Electro-pneumatic;Pneumaticactuator;Hotstampingmachine;On-delaytimer;FluidSIM^®

1. Introduction

ItwasproposedthatCO2canbemitigatedwiththeproduc- tionoflighterweightvehiclestoreducefuelconsumption,and reduceCO2emissionstotheatmosphere(Hagenah,Merklein, Lechner, Schaub, & Lutz, 2015; Li, Chiang, Tseng, & Tsai, 2014a; Li et al., 2014b). Hot stamping technology is oneof thekeywaystooptimizeenergydemandwithintheautomobile manufacturingindustry(Oldenburg,Steinhoff,&Prakash,2008, 2009;Oldenburgetal.,2009;Karbasian&Tekkaya,2010).Hot stampingisamethodthatwasusedinapplyinggoldtoolingin bookprintinginthe19^thcentury(Cambras,2004).Hotstamping

∗Correspondingauthor.

E-mailaddress:[email protected](B.I.Oladapo).

PeerReviewundertheresponsibilityofUniversidadNacionalAutónomade México.

wasofficiallydocumentedinGermanybyErnst(Benedek,2005) in1892astheprintingmethodusedonleatherandpapermateri- als.Hotstampinghasalsobeenadoptedformakingplasticsand printing ofsecurity cardssince1950s(Karbasian&Tekkaya, 2010; Wang&Lee,2013).Hot stampingcanbe definedasa dryprintingprocessoflithographicmaterialinwhichfoilordry paintofdifferentcoloursarebeingsuperimposedonasurface athightemperatures(Benedek,2005).Thisiscommonlyappli- cablewithintheplastic,paperandsecurityindustries.Ithasa minimalpollutioneffectontheenvironment.Theexploitationof hotstampingmachine(HSM)inautomotivebodystructureman- ufacturingisgrowingyearly.Someautomobilecompaniesuse morethan35%hotstampedpartsfortheirmodelsintherecent years(Karbasian&Tekkaya,2010;Wang&Lee,2013).Glob- ally,therehasbeenanincreasingtrendandrapiddevelopment andtechnologicalinnovationintheproductionofpneumatically and electro-pneumatically operated machines (Gamal,Sadek,

http://dx.doi.org/10.1016/j.jart.2017.03.006

1665-6423/©2017UniversidadNacionalAutónomadeMéxico,CentrodeCienciasAplicadasyDesarrolloTecnológico.Thisisanopenaccessarticleunderthe CCBY-NC-NDlicense(http://creativecommons.org/licenses/by-nc-nd/4.0/).

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Rizk,&Abou-elSaoud,2016).Thisisalsovisible withinthe technologicaldevelopmentofHSMs.SomeHSMsmakesuse of compressed air to produce their stamping effect (Harper, 2005).As the compressedair is passedto their systems, the cylinderexpandstoinitiatethe machines’ operations.During hotstampingoperation,aheateddie ofhigher temperatureis mountedonthecylinderheadandtheproducttostampisplaced onatable vicebeneath the stampinghead (Sugimoto,Sakai, Umemoto,Shimizu,&Ozawa,2004).Theprintingisdoneby forcingthehotdieontheworkpiece.Thiscreatesanimpres- siononthesurfaceoftheproductbythedrypaintorfoildies (Benedek,2005).Diescanbemadeofsiliconerubberormetal tohaveahardsurfaceforaninscription;itcanbecastdirectly orbystamping;andit carrieshighlevelsofdetailsembossed onthesurfaceofboththeregularandirregularshapestoforma specificblueprint.Foilshasmultilayeredcoatingsthattransfer theblueprinttothesurfaceoftheproduct(Couchman, 1998).

Thereare metallic andnon-metallicfoils, whichconsist of a releaselayer,acolourlayerandanadhesivebase.Inmetallic foils,thecolourlayerisreplacedwithachromeoravacuum- metallic aluminium layer. Foil dies are available in different metal shades e.g. copper, bronze, silver and gold. Different HSMscanbe used for differentpurposes,butthe most com- mon HSMs are the simple up-and-down presses, which this researchworkisbasedon(Benedek,2005;Couchman,1998;

Gamaletal.,2016).

1.1. Hotstampingmachinesmodeladvantageandsystem description

Recently,Trajkovic,Milosavljevic,Tunestål,andJohansson (2006) investigated diverse types of valves and relays (i.e.

electromagnetic, electro-hydraulic, hydraulic, pneumatic, and electro-pneumatic actuators) for different machines. They reportedonthechallengesbetweenfastresponsevalves,relay andlowflowrate.Itwasparticularlyinterestingthatpneumatic operatedvalveismoreefficientandfitfortheinvestigatedHSM applications(Adeoye, Aderoba,& Oladapo,2017; Watson &

Wakeman,2005).Theelectro-pneumaticandelectro-hydraulic actuatorshavethesameworkingprinciplesexceptthedifference intheirresultantforcegenerationandworkingmedia(Abdel- Hamid,Sohair,&Ahmed,2015;Minh,Tjahjowidodo,Ramon,

&Van, 2009; Ruan, Burton, & Ukrainetz, 2002). The pneu- maticactuatorshavefasterresponsetimewhencomparedwith the hydraulic actuators.Thisis dueto the lowdensity of air adopted by the pneumatic actuators as its operating medium (Abdel-Hamidetal.,2015;Oladapo,Balogun,Afolabi,Azeez,

&Asanta,2015;Minhetal.,2009).Apparently,duetothecom- pressibilityofairanditsnonlinearbehaviour,thecontrolsystem of pneumaticactuators tendstobe difficultinterms of oper- ationability (Minh et al., 2009).The HSMs are operated on theprinciplesofhightemperature andhigh-pressureairasan energy source.The electro-pneumaticvalves(EPV) andtime relayvalves can be improvedoptions to electro-hydraulic or hydraulicsystemofoperation.Inordertodecreasetheincon- sistencybetweentheoutwardmovingforcepredictionandthe experimental measurement, investigations have been carried

out extensively on the precision of the proposed model that evaluatedpneumaticandautomatedelectro-pneumaticdesigns (Minhetal.,2009;Mohamed&Shima,2015;Oladapoetal., 2016).Stampingorpressingistheprocesswherebyflatmate- rialisinsertedintheformofacoilthatpassesthroughthedie into astampingpress toformthe desired shapeof the mate- rial (Davis &Caldwell, 2006; Kalpakjian & Schmid, 2001).

TheHSM hastemperaturerangesbetween40^◦Cand400^◦C, input voltage of 220V and a 600W heating capacity. The HSM heating capacity has a time delay control valve range of 0.1s–10s.Themaximumstroke of thehotplate is80mm from the reference pointand a maximum pressure of 60bar on a one horsepower air compressor. The HSM can contain a hot plate of 140mm×170mm at a time. The time delay valvecan bea normallycloseand/or anormally openvalve.

Anormallyclosetimedelayvalvehasalockadjustingscrew that serves as the valvetimer. The valveis designed tomeet the flow rate requirements. It is a combinational of a 3/2- way valve, an air reservoir and a throttle relief valve. The 3/2-way valve can be of normally open or normally close position.The typeadopted inthisworkisthenormally open timedelayvalve.Thenormallyopenandnormallyclosetime delayvalvesarenormallydesignedtobeactuatedforaperiod between 0 and 30s. This can be extended beyond 30s with additional reservoir. During the hot stamping operation, the pilot of the 3/2-way valveis actuated when the air reservoir pressure is about 12bar (Tokashiki, Fujita, Kagawa, & Pan, 1996).

1.2. Aimandobjectives

Theaim ofthisworkistounderstudythefunctionalvalve of theHSM andtodeterminetheparametersfor itsoptimum performance.Thespecifiedobjectivesareto:

1. Understudy the pneumatically and electro-pneumatically operatedHSMwithaviewtoproposingdefiniteconclusions foritsdesignandoperations.

2. Configure andsimulatethe HSM 3/2 wayvalve normally openspringreturn.Thespringreturnisdesignedwithathrot- tlevalvetoformatimedelayvalvewiththreeoutletsasshown inFigure1(a)and(c).

3. SimulatetheHSMtimedelayvalvewithtwooutletsasshown inFigure1(d)inordertoregulatethetimeoftheforwardand returnstroke.

4. SimulatetheHSM relaywithswitch-ondelayforthetime delayoftheelectro-pneumaticsystem.

1.3. Thestructureofelectro-pneumaticdriveforHSM The setupof theelectro-pneumatic drivewithFluidSIM^® systemis as shownin Figure2.Aschematic diagramof the electro-pneumaticcontrolsystem(EPCS)wasadoptedtocheck thestatusofthestampspeed,delaytimeandsmoothmovement ofthecylinder.

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A B

D

C ¹²

12 3

2

1

2

1 3

Fig.1.(a)Functionaltimedelayvalvewiththreeoutlets,(b)timedelayvalve withtwooutlets,(c)schematicrepresentationofatimedelayvalve,(d)symbol ofatimedelayvalve.

2. Mathematicalmodellingofpneumaticsystem

Inordertoevaluatetheperformanceoftheairinthecylinder andthepneumaticbehaviour,themathematicalanalysisofthe air,thecylinderandthepistonmustbeexamined.Airisknownto

beanincompressiblemulticomponentfluid,whichcomposedof dryairandwatervapourinthermalequilibrium.Thepressure, velocity, areaof thecylinder andpistonand the flow rate of thedouble-actingcylinderisshowninFigure3.Thefollowing assumptionsareconsiderintheequation:

• Theairflowissteadystateandlaminar.

• Thegravitationalforceontheairisnegligible.

• Areaoftheconnectingtubeisconstantinlinearity.

• Thetemperaionofthesystemiskeptconstant.

Thegeneralmodelforcontinuousflowofthesystemlinearity oftheflowrateofairisgivenbythefollowingequations:

q1+q2+2q³=c0

P·l+(a¹+a2)˙x, (1)

q1+q2=−kpPl (2)

q1+q2=k_iA_i−k_p0Pl (3) wherea1=P1A1/RTs;a2=P2A2/RTs;q1,q2 andq3 represent theflowratethrougheachofthevalves;xiscontrollingpiston position;V1andV2arevolumesofthedoubleactingcylinder;P1

andP2aretheinputandoutputpressuresappliedrespectivelyto thesystemandAiisthecross-sectionalareaofthedoubleacting cylindershowninFigure3.Thedynamicequationofmotionof thepiston-rodisdescribedas:

M_rd

dt˙x+β˙x+F_f +F_L=P1A1−P2A2−P_aA_r (4) where,MPisthemassofthepiston,xisthepistonpositionata particularpointintime,βisthecoefficientofviscousfriction,Ff

1 A 1 1B1

1B1

1 P 10.00 5.00 1 P 2 +24V

2 4

5 1

3

1M2

1 2 3 4 5

13

14 BU

BK

K1

14 14

11 11

K2

A1

A2 5 K2

1M1

1M2 S1

K1

0V 2

0 Z

3

4 5

A1

A2 BN

Fig.2.Theschematicdiagramoftheelectro-pneumaticcircuitintheHSM.

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Sensors Position (x)

A₁ V₁

A₂ V₂

q₁

A B

P1

q₂

p₂

V₃ F₃

Fig.3.Schematicrepresentationofthedouble-actingpneumaticactuatingcylinder.

istheCoulombfrictionforce,FListheexternalforcefromthe stamp,P1andP2aretheabsolutepressuresinthecylinder,PA istheabsolutepressure.A1andA2–thepistoneffectiveareas, Ar–therodcrosssectionalarea.

Few researchers for example (Beater, 2007; Ilyukhin &

Arfikyan,2011;Richer&Hurmuzlu,2000;Takosoglu&Laski, 2011;Tokashikietal.,1996)proposedthemathematicalmodel usedtoanalyzetheelectro-pneumaticcontrolsystemsactuating adoubleactingcylinder forHSMs.In their models,the time delay5/2pneumaticvalvewithdoubleairpilotwassimulated andcontrolledby the computer andworkstation for boththe forward andthe backward strokes.The modelsare basedon fourdifferentialequationswhichdescribethedynamicsofthe pneumaticcylinderpressuresandspecifytheprogressivemove- mentofthemechanicalcontrolsystem,showninEq.(4).The equationsconsiderthedirectionoftheflowthroughthethrottle valve.

dx

dt =v, (5)

dv dt = F

m, (6)

dP1

dt =n.R.T.G1−A1.P1.v

V02−A1.x (7)

dP2

dt =n.−R.T.G2−A2.P2.v

V02−A2.x (8)

wherevisthespeedofthepiston,Ristheuniversalgascon- stant,Tistheworkingtemperatureofthecompressedair;nis coefficient;Fistheforceontheoutputofthecylinderusedto calculatetheactingforceonthepiston.

2.1. Developedmodelequation

FromEq.(1)substitutingthevalueofa1anda2,andifthe temperatureiskeptconstant,thenthemodelequationisasshown inEq.(9).

q1+q2=c0Pi+

P1A1+P1A2

R

˙x (9)

Ifalltheparametersof thesystemaretakenintoconsider- ation.WhereA1=0.00031415m²,A2=0.0002638m²,x=0.1m and R is the specific dry air constant=287.05Jkg⁻¹K⁻¹. TheworkinginputpressuresareP1=5.05barandP2=0.0bar deducedfromtheresultinFigures7and8.Thus,whenthereis aninputpressurethereisnooutputpressureandvicevisa.

Thereforesubstitutingallparameters,thegeneralmodelfor continuousflowofthesystemisgivenbyEq.(10).

q1+q2=C0p_i+0.00553d

dt(x) (10)

3. Experimentalset-up

The component part of the HSM systemmechanism isas showninTables1and2 forthe EPCSandPCSrespectively.

Thisconsistsof:1)pneumaticdoubleactingcylinders,whichact asthemechanicalstampingpiston;2)5/2-waysolenoidimpulse valvepneumatically/electricallypilotedwithamanualoverride;

3)thesupplyingelementthatconsistsofthecompressedairsup- plyandairserviceunit;4)thepushbuttonswitchthatclosesat theactuationofthesystemandopensimmediatelyafterreleased;

5)therelay,whichimmediatelyswitchonwhencurrentispassed

Table1

DescriptionpartlistforEPCS.

Numberofitem Designation Description

1 1A1 Doubleactingcylinder

1 Compressedairsupply

1 0Z1 Airserviceunit,simplifiedrepresentation 3/2-wayvalve,manuallyoperated

1 1V1 5/2-waydoublesolenoidimpulsevalve

1 Electricalconnection24V

1 Electricalconnection0V

2 K2 Relaywithswitch-ondelay

1 K1 Relay

1 1M1 Valvesolenoid

1 1M2 Valvesolenoid

1 1S1 Pushbutton(make)

1 K1 Makeswitch

1 K2 Makeswitch

1 1B1 Inductiveproximityswitch

1 1B1 Distancerule

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Table2

DescriptionpartlistforPCS.

Numberofitem Designation Description

1 1A1 Doubleactingcylinder

1 Compressedairsupply

1 0Z1 Airserviceunit,simplifiedrepresentation

1 1V2 Timedelayvalve,normallyclosed

1 0V1 3/2-wayvalve,manuallyoperated

1 1V1 5/2-wayvalve,manuallyoperated

1 1S1 3/2-wayvalvewithpushbutton

1 1S2 3/2-wayrollerlevervalve

1 1B1 Distancerule

andswitchoffimmediatelycurrentisremovedfromthecircuit;

6) the magnetic proximityswitches whichserve as the work piecein the experimental setup;7) the relay,with switch-on delay that determinesthetimedelay of the pistonmovement and8)thevalvesolenoidthatswitchesonthe5/2-waysolenoid impulsevalve.

Thearrangementof thecomponent partsthat madeupthe HSMsystemmechanismthatiscreatedtobehaveliketheHSM fortheEPCSandPCSareasshowninFigures4and5respec- tively.From Figures4 and5,itcanbeseenthatthepartsare systematicallyarrangedtodepictthesequentialandlogicflow oftheHSMprocess.

24V CONNECTION

Air Service Unit

OV connection

Inductive proximity switch

Distance Rule Double Acting Cylinder

5/2-way solenoid impulse valve

Fig.4.ExperimentalsetupofEPCS.

Air Service Unit

Air Distribution

Distance Rule

Connecting Holes 5/2-way, Impulse

3/2-way valve, Pushbutton

Throttle valve

Configure pneumatic 3/2-way 3/2-way roller lever Double Acting Cylinder

Fig.5.PictureofexperimentalsetupforPCS.

1A1

1B1

0.00 5.05

1V1 4 2

12

3 1 5

1S1 2

3 2

12

1V2 2

3 1

1 3

2

3 1 0 Z

1B1 1

14

Fig.6.TheschematicdiagramofthepneumaticsimulationofcircuitinHSM.

V supply to theinductive sensorthat servesas the work piece forquick return.

The stamping control system was also designed with the pneumatic FluidSIM^® software as shown in Figure 6. From Figure 6, thecylinder headis actuatedwithaforward stroke by depressing the pushbutton 1B1 as shown in Figure 6 in the pneumaticcircuit.Itsendssignalstothe5/2-wayimpulse pneumaticallydoublepilotedvalvecontroller1V1andopenthe inflowofhigh-pressureaircomingdirectlyfromthecompres- sor.Thedoubleactingcylinderisbeingactuatedbyacombined signalsentfromthe3/2rollerlevervalve,normallycloseand the5/2-wayvalve.Theairflowsfromthecompressorthrough the3/2rollervalvetothetimedelaynormallyopenfunctional valve.Thiscausesthecylindertomoveforwardandbackward afteraspecifiedtime.

Thedescriptionandthedesignationofeachpartofthecom- ponentinFigures3and6areitemizedinTables1and2.The flow rate of the system that reachesthe doubleactingcylinder is determined bythe flow rate of the compressor,the air servicesystemsandtheopeninglevelofthetimedelayvalve.

The 5/2-wayimpulse doublepneumaticallypilotedvalveand the longitudinalslidevalvehavefiveportsandtwopositions.

Thisisusedasafinalcontrolelement thatlinksthevalvesto the doubleactingcylinderandtothe 3/2-wayvalvewithnor- mallyclosedpushbuttonwithaspringreturn.Thecontrolvalve hasthreeportandamanuallyoperatedswitchforactuation.A mechanicallypilotedspringreturn3/2-wayrollerlevervalveis used toactivatethe movement of the doubleactingcylinder.

Thenormallyclosedtimedelayvalveismadeupofapneumati- callyoperatedairpiloted3/2-wayvalve,aone-wayflowcontrol valve(throttlevalve)andanairaccumulatorthatregulatesthe

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timedelay oftheairinflow.TheFESTOFluidSIM^® software isadoptedtosimulatetheHSMcontrolsystem.Thedeveloped FESTO FluidSIM^® consistof: the normallyclose timedelay valveDSNU-20-100-PPV-A,the5/2singlepilotconfiguredto asinglepilotedspringreturnnormallyclosed3/2valveD:TP- BG-VL-S/2-Q4,athrottlevalveD:TP-PPV-GRLAforopening thecompressedair,thetimeadjustmentvalveD:TP-BG-PZVT- 3/2G-3OS-Q4usedtoacquiretheexperimentaldata,themetre rulefordistancemeasurement,anairservicewithanairfilterthat regulatestheairflowstatesdesignatedD:TP-PVV-LFR-MICFQ andthepistonadoptedwhichisdesignatedDSNU-20-100-PPV- AasshowninFigures4and5.Thepistonrod,pistondiameter andthestrokelengthoftherodcylinderwere8mm,20mm,and 100mmrespectively.Alinearscaleof200mmlong,measured thedisplacementofthecylinderbeforeandafterexcitation.The airpressureismeasuredwitha10barpressuregauge.Theexper- imentswerecarried outunderamaximumpressureof6.0bar forsafetyandinordernottoexceedtheoperatingpressureof theHSM(Fig.7).

4. Resultsanddiscussions

Different computer simulations and experimental process ware carried outby meansof the developedmodel shownin Figures8and9.Thefollowingresultswereobtainedtoascer- tain theworkabilityofthesystem.First,intheprocessof the HSM,speedmovementoftheFESTOFluidSIM^®platformswas observed.Thepositioningdistance,velocityandaccelerationof theactuator(theactuatoristhemainstampingarmsofthecylin- derwherethestamping,padisattachedtoaidtheprocesses)that isusedforthestampingarmofthemachinewerecontrolled.As theprocessprogressesandasthepressurelevelofthecompres- sorreaches6bar, itwasobservedthattherewasafluctuation onthemovementofthepressuredroppinglowerthanthe6bar beforeincreasingfurtheruptothe6barmarkafterabout0.06sof operation.Thisphenomenonwasnoticedonthepressuregauges forbothpneumaticandelectro-pneumaticexperimentalvalue.

Thesimulatedanalysisalsoexhibitedthedropandhigh-pressure differencesasshowninFigure8butnosignificantdifferencein

0 1

Quantity value

Position mm

Position mm Quantity vlaue

Velocity m/s

Switching position

Pressure bar

Pressure

bar Pressure

bar

100 80 60 40 20

2 0 1 2 2 4

100 80 60 40 20

0.80 0.60 0.40 0.20 0 -0.20 -0.40 -0.60

0.80 0.60 0.40 0.20 0

a -0.20 -0.40 -0.60 a

0 5 4 3 2 1

5 4 3 2 1

A B

Fig.7.(A)Thesimulationdiagramresultofdependenceofpositionandvelocityontimeofpneumaticsystem5%openingoftimedelayvalve.(B)Thesimulation diagramresultofdependenceofpositionandvelocityontimeofpneumaticsystem75%openingoftimedelayvalve.

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Quantity value

Position

mm Position

mm

0 100

80 60

40

20

100 80

60 40

20

5 4 3

2

1

5 4 3

2

1

5 4 3

2

1

5

4 3

2 1 1.50

1 0.50 0 -0.50 -1

1

1.50 1 0.50 0 -0.50 -1

1 1

0

1 2

2 3 4

Velocity

m/s Velocity

m/s

State

Pressure

bar Pressure

bar

Pressure bar

1Z1 1Z1

1Z2 1Z2

A B

Fig.8.(A)Simulationresultofelectro-pneumaticsystem2srelaywithswitchon-delay.(B)simulationresultofelectro-pneumaticsystem0.5srelaywithswitch on-delay.

Thetimedelayforalloymaterialshouldbedifferentfromnon-alloymaterial.FromFigs.7–9itcanbeseenthattherelayswitchwasonlyactivatedatthereturn strokeofthecylinderforallthetestcarryoutwhichmeansitisthepartofcomponentthatactivatethereturnstroke.Theinductiveproximityswitchshowsthe positionofthecylinderatapointintime.

theresultobtained.Fromtheanalysisoftheactuator.Themag- neticcushionof thedoubleactingcylinderhelptoreducethe suddeninitialkick-offofthesystemfromwithinthetimeframe of 0.4s.Thisaid theslowdownmovementofthe actuatorin ordertohavegoodandstableimpressionwithouttheapplica- tionofanimpulsiveforcewhichcouldcreateadentandadefault impressionontheworkpiece.Ithasbeenproposedintheliter- ature(Lietal.,2014a;Lietal.,2014b;Oldenburgetal.,2008, 2009)thataforceexertedbyapressureof 6barisenoughto createanimpressionontheworkpiecewhenheated.

Atthepointofactuationtherewasaflowofairfromthesup- plyunitthroughtheairservicestationtothecontrolvalvefor 5/2-way solenoidimpulse valve and5/2-wayimpulse double pneumatically piloted valve for electro-pneumatic and pneumatic system respectivelyas shown in Figure 7. Air is then suppliedwitha3/2rollerlevervalvewhichservedasthework- pieceinthesystemandtheon-delaytimervalvethatcontrols the time of movement of the piston. From Figure 5, on the electro-pneumatic system, the electric signal is passed from the22v.

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5 4.5 4 3.5 3 2.5 2 1.5 1 0.5 0

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

0

Time(s)

0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

0 0.5 1 1.5 2

Time(s)

Time(s) Time(s)

1Z1(bar) 1Z1(Mpa)

1Z1(Mpa) 1Z1(Mpa)

1Z2(Mpa)

1Z2(Mpa) 1Z2(Mpa)

Distance(mm)*20

Distance(mm)*20 Distance(mm)*20

1Z2(bar) Distance(mm)*20

2.5 3 3.5 4

0 0.5 1 1.5 2 2.5 3 3.5

A

C D

B

Fig.9.Theexperimentalresultofdependenceofpositionandvelocityontimeofpneumaticsystem5%openingoftimedelayvalve.(B)Experimentalresultof dependenceofpositionandvelocityontimeofpneumaticsystem75%openingoftimedelayvalve.(C)Experimentalresultofelectro-pneumaticsystem2srelay toswitchon-delay(D)Experimentalresultofelectro-pneumaticsystem0.5srelaytoswitchon-delay.

5. Conclusions

The electro-pneumatic and pneumatic system for the hot stampingmachineispresentedinthispaper.Theon-delaytimer valvewas designed,developedandconfiguredontheFESTO didacticworkbench inordertomimic andsimulatethe HSM pneumaticsystemforsustainableperformance.Thesimulated HSMwasbuiltusingthe mainHSM components.The experimental and simulation results show the characteristics and behaviourof theairmovementwithinthe system.Thisresult isalsoaproofthatthedelaytimeofthesystemcanbeobtained moreprecisely and accurately withthe on-delay timer valve incorporatedinthe assemblyas shownbythesimulation and experimentalanalysesconducted inthiswork.Thisishelpful toadvancetheperformanceandoptimizationoftheHSM.The followingconclusioncanfurtherbedrawnfromthiswork:

• Itcanbe observedthatthe possibilityof magneticcushion systematthe two ends of the adopted standardpneumatic cylinderspreventedthesuddenstampingoftheworkpiece.

Hence, to avoid increase in scrap and/or rework rate due

to sudden stampingin HSM, it is proposed that magnetic cushion systembeincorporatedintotheHSM.Thissystem canprovidetherequiredshocksabsorberduringtheHSM’s stampingoperations.

• Although,Itcanbededucedfromboththesimulationsand experimentalsetupthat thepneumaticoperatedsystemfor on-delaytimingisunpredictable,theHSMcanbeoperated withboththepneumaticandelectro-pneumaticsystemvari- ablesdependingonthe workpiecematerial.The workpiece materialdeterminestheamountofforcetobeexertedduring astampingoperation.

• Itisalsoclearthatthecycletimevariesdependingonthein- flowofairfromthesupplyelement.Henceforsustainability andprocessoptimization,itisproposedthattheHSMbecon- trolledwitha24Vinputelectricalenergyunderspecifiedtime durationforthedelaytimeontheworkpiecessincethe24V inputsupplyontheelectro-pneumaticoperatedHSMhelps to reducethe electricalenergy consumption when HSM is incorporatedwithelectro-pneumaticandpneumaticsystem.

Thiscouldfurthercreateanawarenessontheelectricalenergy consumptionoftheindustrialbasedHSMinordertoimprove

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theresourcewasteandincreasetheeconomicobjectivefor theHSMusage.

• The reductionintheconsumptionof electricalenergywith theproposed24VforPCSandEPCScouldfurtherreduce theemissionofCO2totheenvironmentwhichinturnreduces carbonfootprintoftheHotStampingMachineoperations.

Conﬂictofinterest

Theauthorshavenoconflictsofinteresttodeclare.

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