Forming - · PDF fileDifferentiation of blanking and perforating blanking piercing waste...

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Forming - Blanking

Manufacturing Technology II

Lecture 6

Laboratory for Machine Tools and Production Engineering

Chair of Manufacturing Technology

Prof. Dr.-Ing. Dr.-Ing. E.h. F. Klocke

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Content

Introduction

Demands on blanking parts

Shearing

Fine blanking

Laser cutting

Water-jet cutting

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Deep DrawingIroningSpinningHydroformingWire DrawingPipe DrawingCollar Forming

Casting Forming Cutting Joining Coating Changing of Material Properties

CompressiveForming

Tenso-Compressive

Forming

TensileForming Bend Forming Shear

Forming Severing

TranslateTwistIntersperse

Manufacturing Processesaccording to DIN 8580ff

Open DieForgingClosed Die ForgingCold Extrusion Rod ExtrusionRollingUpsettingHobbingThread Rolling

Stretch FormingExtendingExpandingEmbossing

With linear Tool MovementWithrotating Tool Movement

ShearingFine BlankingCutting with a single BladeCutting withtwo approachingBladesSplittingTearing

IntroductionSheet Forming Process

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IntroductionWhat is blanking?

Definition:

Mechanical separation of workpieces without appearance of shapeless material, therefore without chips … if necessary, including additional forming-operations.

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Content

Introduction


Shearing

Fine blanking

Laser cutting

Water-jet cutting

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Demands on blanking partsRequired quality of blanking parts

surface evenness

smooth sheared zone

cutting burr

rupture zone

draw-in

achievableroughness

angular deviation

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Content

Introduction


Shearing– Introduction– Characterisation of the process– Achievable accuracy– Forces in shearing– Wear– Tool design– Examples of sheared parts

Fine blanking

Laser cutting

Water-jet cutting

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Shearing - IntroductionShearing – Introduction

application IT-classification costs output

Shearing

high

rough (IT 11) low high

lowfine (IT 7)

shearedsurface

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Shearing - Characterisation of the processOpen and closed cut in shearing

open cut closed cut

tool flank open flank

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Shearing - Characterisation of the processDifferentiation of blanking and perforating

blanking piercing

waste

waste

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Shearing - Characterisation of the processTool design of shearing

punch

sheet metal

blanking die

u – die clearenceapp. 0,05 x sheet thicknesswith:u = ½ · (a – a1)

a – dimension of cutting die

a1 – punch dimension

α – relief angle of cutting die

Ublank holder


Shearing - Characterisation of the processProcess sequences of shearing

1 2

3 4

charging of the punch

elastic& plasticdeformation

shearing& cracking

break through

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Shearing - Characterisation of the process

Stresses in shearing

cuttingdie

punch

F

F

τ

τσ σ

shearing and tensile stresses cause cracking


Shearing – Achievable accuracyErrors on sheared workpieces

burr height hG

draw-in height hE

draw-in

shearing zone

rupture zone

ttRR

hhGG

hhEE

crack depth tR

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Shearing – Achievable accuracyInfluence of die clearance on the sheared surfaces

smallclearance

bigclearance

By a small die clearance, distortion wedges are generated by squeezing of a the material between two cracks.

no formation of distortion wedge

formation of distortion wedge


Shearing – Achievable accuracyQuality of sheared surface depending on specific die clearance

spec

ific

die

clea

ranc

e:

die

clea

ranc

eu S

/ she

etth

ickn

ess

s

9


Shearing – Achievable accuracyInfluence of specific die clearance on crack depth

blanking

specific die clearance us / %

Cra

ck d

epth

t Rsh

eett

hick

ness

s


Shearing – Achievable accuracyRelation between burr height and number of cuts

ductilesheet

brittlesheet

burr height

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Shearing - Forces in shearingReduction of cutting force by modification of tools

Contact between punch and sheet

slopedcut

planecut

s h

total punch stroke

forc

e F

0 s 2s 3s

0,3 Fmax

0,6 Fmax

0,9 Fmax

Fmaxh = 0 (plane cut)

h = 1/3 s (sloped cut)

h = s (sloped cut)

h = 2s(sloped cut)

=

work s(h=0) = work s(h=2s)

Due to workpiece-bending, sloped cut is only suited for piercing.


Shearing - Forces in shearingReduction of cutting force by modification of tools

conical punchgrooved punchplane cut sloped cut

conical die grooved die punch offset

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Shearing - Forces in shearingDependence of quality on shearing strength of carbon steel

carbon concentration tensile strenght breaking elongation sheet thickness

die clearance part diameter aspect ratio draw-in

Cutting resistance is defined as the cutting force (Fs) referring to the cutting surface (As= ls*s)


Shearing – WearWear on the punch

wear on shaft area

wear on front facefatigue wear on front face

fatigue wear and wear on front face espacially appear for lowersheet thickness (s < 2 mm)

wear on shaft area is caused byfriction between punch and sheetin direction of punch movement. Appears during cutting of thickersheets (s ≥ 2 mm)

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open cut

Workpiece

Shearing – wearInfluences on wear

Source: reiner, Müller Weingarten, Feintool

Tool Machine

Type of process

tool wear

materialhardnesssurfaceguidancedie clearance

stiffnesskinematics

alloystiffnesshardnessdimensionshape

open cutclosed cut

closed cut


Shearing – Tool design

Multi-stage blanking tool

4 stageMulti-stage blanking toolfor shearing of rotor- and stator-sheets

stator rotor

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Shearing - Examples of sheared partsMulti-stage cut including assembly of an electronic connector

Gesamtlaufzeit1:49 min


Content

Introduction


Shearing

Fine blanking– Introduction– Characterisation of the process– Process details and degree of difficulty– Achievable accuracy– Field of application– Tool design– Production examples

Laser cutting

Water-jet cutting

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Fine blanking - IntroductionFine blanking - Introduction

application IT-classification costs output

shearing

fine blanking

high

rough (IT 11) low high

lowfine (IT 7)

shearedsurface


Fine blanking – Characterisation of the processAnimation of fine blanking

clamping

plastic deformation

cutting

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Fine blanking – Characterisation of the processStresses in fine blanking

cutting die

punch

F

F

τ

τσ σ

counterpunch

blankholderwith veering

F

F

σ

σ

σ

σ

σ

σ

σ

σ

σ

σ

superposed compression prevents cracking


fine fine blankingblankingshearingshearing

1 – cutting die(2 – guiding plate)3 – punch

FS – punch force

1 – cutting die2 – vee ring and

blank holder3 – punch4 – counter punch

FS – punch forceFR – vee ring and blank

holder forceFG – counter punch

force

Fine blanking – Characterisation of the processDifferences between shearing and fine blanking

die clearance5% 0,5%

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Fine blanking – DetailsGeometry of vee rings

thin sheets

thick sheets

sheet thickness s5 – 15 mm

sheet thickness s3 – 5 mm

blank holderwith vee ring

cutting die

• create compression stresses• prevent horizontal movement of the

sheet / material flow

vee ringcutting line

toothed

inward notch

outward notch

vee ring cutting line

intention:


Fine blanking - DetailsDependence of workpiece quality on influencing quantities

counter punch force draw-in width draw-in height

smooth shearingzone deflexion

Process parameters affect workpiece quality:example:

draw-in height die clearance sheet thickness

blank holder force counter punchforce

Workpiece quality can be influenced by process parameters:example:

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Fine blanking – obtainable precisionDefinition of degree of difficulty in fine blanking

slot

a, s

tick

b / m

m

sheet thickness s / mm

edge

radi

usr i

, ra

/ mm


degree of difficultyS1 – easyS2 – mediumS3 – difficultedge angle a


Fine blanking – comparison of techniquesComparison of sheared surface in shearing and fine blanking

shearing

fine blanking

In fine blanking, the smooth sheared zone can take a share of 100%

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Fine blanking –applicationApplication examples

fine blanking

shearing

In fine blanking, the sheared surface can be used as a functional surface


Fine blanking – Field of applicationApplication examples in automotive industry

valve plate

gear shifting gate door lock window lift

synchronising disc

belt pretensioner

ABS-pulse generator

cooling systemseat belt componentsseat adjustment

brakes

gear

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Fine blanking – Tool designExample for a compound press tool

In fine blanking, several cuts can be done at the same time.


Fine blanking – Tool designCompound press tool – disc brake

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Fine blanking – Tool designExample for a multi-stage tools

fine blanking of a disc using multi-stage tool fine blanking of a clutch disc

stage 1: fine blankingstage 2: burr stamping

stage 1

stage 2

Feeddirection


Fine blanking – Tool design

follow-on composite tool3 stages in a Follow-on composite tool

forming –thread forming –fine blanking

connecting strap of a car door

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Gesamtlaufzeit2:13 min

Fine blanking – Production examplesProduction of a clutch disc


combined fine blanking / forming

Fine blanking – Production examplesPlanet carrier: Starting point

A combination of fine blanking and forming realises the production of complex parts

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example „planet carrier“

alternative A- inappropriate contur for forming- requires machining

alternative B- No mashining required

Fine blanking – Production examples

Example planet carrier: Approach

properly for manufacturing through Redesign


Fine blanking – Production examples

Planet carrier: Implementation in an 8-stage follow-on composite tool

pre-blanking, pin stop hole

bending tabs 45°chamfering of hole

fine blankingof slots and holes

step coiningpiercing Ø39 H9

shape coining of tabs bend tab 90° burr stampingat slots final cut

1

2

3

4

5

6

7

8

Development of forming and blanking sequence

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Fine blanking – Production examplesPlanet carrier: Follow-on composite tool in modular design

bottom tool upper tool


Fine blanking – Production examplesPlanet carrier: Follow-on composite tool in modular design

1 2 3 4 5 6 7 8

stages / module

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Content

Introdution


Shearing

Fine blanking

Laser cutting

Water-jet cutting


Laser cutting – Characterisation of the processPrinciple of laser cutting

Cutting by local melting and exhausting of material

power power distributiondistributionacrossacross laserlaser--profileprofile

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Laser cutting – process variablesCutting speed for several materials

CO2-laser, PL max = 2,6 kW

12

8

4

0 84 12 16 20

feed

spee

dv f

/ m min


structural steel (O2 0,5 – 4 bar)CrNi - steel (O2 0,5 – 4 bar)Al. - alloy (O2 10 – 18 bar)

Top feed speed depends on material and sheet thickness


15

10

5

0 84 12 16 20

feed

spee

dv f

/ m min

sheet thickness structural steel s / mm24

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Laser cutting – process variablesComparison of cutting speeds

shearinglaser cutting (1500 W)water-jet cutting

Top feed speed depends on material and sheet thicknessQuelle: TrumpfQuelle: Trumpf

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special process:rotational cutting

St37465mm x 5400mm x 2mm

contourA

B

C

shearing(rotational)

30 sec

4 sec

3 sec

laser cut

17 sec

16 sec

12 sec

nibbling

40 sec

-

15 sec

flexibility

speed

Laser cutting – Process comparisonComparision shearing - nibbling - laser beam cutting


Laser cutting – process variablesComparison of machinable sheet thicknesses

structural steelhigh-grade steelaluminium

shearing

laser-jetcutting(1500 W)

laser-jetcutting(2600 W)

water-jetcutting

0 20 40 60 80sheet thickness / mm

Quelle: TrumpfQuelle: Trumpf

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Laser cutting – Field of applicationExamples of series production

electronic connector (low lot sizes)

climbing clamp

synchronising disc

stator sheet for special enginesQuelle: tecnologix


Content

Introdution


Shearing

Fine blanking

Laser cutting

Water-jet cutting

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principle

water supply

abrasive medium

mixing pipeguard

Water-jet cutting – Characterisation of the processSystem design


Verrundung derSt rahleintrit t skante

Konizität der Schnit t fuge

Abplatzungen amStrahlaust rit t

Riefen, Auswaschungen,Risse auf Schnit t f lächen

Quellenangabe: XYZ

Water-jet cuttingProperties of the jet groove

rounding off at the jet entry

beveled hole

chipping at the exit

scoring, erosion and cracks on thesurface

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Water-jet cuttingcutted surfaces and gaps

1

2

1

2

vf = 20 mm/min

Rz,1 = 25 µm

Rz,2 = 30 µm

vf = 200 mm/min

Rz,1 = 25 µm

Rz,2 = 140 µm

surface gap

material : AlMgSiO.5 abrasive medium : Granat 80 Meshsheet thickness : 25 mm mass flow : 400 g/min

pressure : 300 MPa

feed speed

The surface quality is heavily dependent on the feed speed


Water-jet cutting – process parametersCharacteristic of the surface

α : angle of shoulderbG : burr widthb0 : width of „jet influenced zone“bSO : notch width on workpiece topbSu : notch width on workpiece bottom

hG : burr heightR0 : edge radiusu : rectangular and inclination toleranceM : measuring range of u s : sheet thickness

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Water-jet cutting – influencing parametersInfluences on notch width

0,5

1

1,5

2

2,5

3

3,5

0 2 4 6 8 10 12 0 2 4 6 8 10 12

0,5

1

1,5

2

2,5no

tch

wid

thb S

O/ m

m

notc

hw

idth

b SU

/ mm

treatment distance aD / mm treatment distance aD / mm

pressure : 300 MPa focussing pipe diameternozzle diameter : 0,3 mm d = 1,8 mmlenght of focussing pipe : 50 mmfeed speed : 50 mm / min d = 1,5 mmabrasive medium : Granat 80 Meshmass flow : 250 g / min d = 1,2 mmmaterial : AlMgSi0.5sheet thickness : 5 mm d = 0,8 mm


Water-jet cutting – DependencesDependence of surface quality on particle size

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nozzle diameter : 0,3 mm materiallenght of focussing pipe : 50 mm : AlMgSi0.5abrasive medium : Granat 80 Mesh : TiAl6V4mass flow : 250 g / min : 1.4375

Water-jet cutting – Performance characteristicPerformance characteristics of different materials

00 150 200 250 300

20

40

60

80

00 150 200 250 300

20

40

60

80

feed speed / mm/minpressure / MPa

dept

hof

not

chh K

/ mm

dept

hof

not

chh K

/ mm

Forming - · PDF fileDifferentiation of blanking and perforating blanking piercing waste...

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Transcript of Forming - · PDF fileDifferentiation of blanking and perforating blanking piercing waste...