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Flexible Rolling of Tailor Rolled Blanks- innovative light weight design in steel -

Dr.-Ing. Michael RehseMuhr und Bender KG

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During the past 5 years, lightweight construction potential, feasibility, competitiveness and volume production capability of Flexible Rolling have been verified.

Tailor Rolled Blanks

- a light weight design opportunity -

• Flexible Rolling is a continuous rolling process with periodically varying thickness.

• Mubea developed the complete process chain for a steel component made of TRB

• The adoption of TRB in the automotive industry offers great potential for the optimization of weight, function, cost and complexity.

• Verification of competitiveness: supply orders with Audi, BMW, DCX, GM & Skoda ( 31 parts)

• Ongoing launches in Europe and North America

• Serial production of Tailor Rolled Tubes with an annual capacity of 1 million tubes

• Application studies for multiple car and truck bodies

• Verification of volume production capability: 16,500 to / 5.75 million blanks up to now

Side Member Reinforcement Rocker Cross Member Rear Axle

Heel Cross Member Side Member Rear Seat Cross Member

Front Seat Cross Member Cockpit Cross Member Connection Member

Bumper Reinforcement Safety Belt Side Member

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Mubea – as a lightweight design specialist – supplies automotive OEM‘s worldwide with steel based products. Using Mubea lightweight innovations, a weight reduction of 20 kg per vehicle can be achieved.

SuspensionComponents

System ComponentsSuspension

Stabilizer Bars

Suspension Coil Springs

Engine Components

Hose ClampsValve Springs CamshaftsBelt Tensioner systems Body &Interior

Head Rests

Tailor Rolled Tubes

Tailor Rolled BlanksTransmission Components

Transmission Disc Springs Drive and Transmission Shafts

Mubea Group

Product Range

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Mubea Group

Worldwide presence

Over 4,200 employees @ 15 production sites enable us to serve the customers worldwide.

Taubaté, Brazil

Taicang, China

Warnstedt, GermanyAttendorn, Germany

Production plant

Development Center

Florence, KY, USA Zebrák, Czech Republic

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Mubea Group

Sales development

Mubea strives for a continuous growth in the coming years.

2000 2002 2004 2006 2010

Sale

s in

M €

Target 2010:1 billion €

368445

547

689

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Mubea has a long experience in cold rolling.

Mubea Cold Rolling Mill

Many years of experience in the cold rolling area

Annual production of 30.000 t / year

Core competence in the following materials

- Spring steels- Mild and higher-tensile steels

Expansion of the cold rolling mill in two steps

Flexible rolling facility I: 10.000 t / yearFlexible rolling facility II: 60.000 t / yearMaterials:- Deep-draw grades- Micro-alloyed steels- Higher-tensile steels

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Mubea is convinced that lasting success can only be achieved in partnerships.

Principle of Flexible Rolling

• Defined sheet metal thickness contours

• Uniform thickness transition areas

• High efficiency as strip rolling process

• Can be applied to all rollable metals

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Flexible Rolling allows to produce components with almost all thinkable thickness changes.

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0 100 200 300 400 500 600 700Meßweg in mm

Ban

ddic

ke in

mm

gewalzte BandkonturSollprofil

0,00,20,40,60,81,01,21,41,6

0 200 400 600 800 1000Meßweg in mm

Ban

ddic

ke in

mm

gewalzte BandkonturSollprofil

strip length in mm

strip length in mm

Strip

thic

knes

s in

mm

Strip

thic

knes

s in

mm

Varying sheet metal thickness with smooth

transitions

50% max. thickness reduction

Slope between 1/3000 up to 1/100

Thickness tolerances 50µm

Optimized sheet thickness dependent upon

the load

The cost of the component does not

depend on number of thickness steps

Reduction of sheet and component weight

TRB Properties

Feasible Profile Shapes

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0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

0 100 200 300 400 500 600 700

Meßweg in mm

Ban

ddic

ke in

mm

gewalztes Bandprofil

Sollprofil

0,0

0,2

0,4

0,6

0,8

1,0

1,2

1,4

1,6

1,8

TRB PropertiesSt

rip th

ickn

ess

in m

m

strip length in mm

Varying sheet metal thickness with smooth

transitions

50% max. thickness reduction

Slope between 1/3000 up to 1/100

Thickness tolerances 50µm

Optimized sheet thickness dependent upon

the load

The cost of the component does not depend

on number of thickness steps

Reduction of sheet and component weight

0 200 400 600 800 1000strip length in mm

Strip

thic

knes

sin

mm

gewalzte BandkonturSollprofil

Flexible Rolling allows to produce components with almost all thinkable thickness changes.

Feasible Profile Shapes

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Mubea has developed the complete process chain for a steel componentmade of Flexibly Rolled Parts.

Flexible Rollingcoil to coil

hood-typeannealing furnace

stripgalvanizing

profile levellingand cutting

profile forminginto a part

part with differentSheet thicknesses

Process chain of Tailor Rolled Blanks

Principle and Status of TRB

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Cold Rolling Plant in Attendorn

Start of construction work: Ma `03Completion of building: Jan `04Start of equipment installation: Feb `04First Coil: Aug `04Capacity: 60.000 t/year

FlexWalze 1Prinzip und Status von TRB

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Process chain of Tailor Rolled Parts

Principle and Status of TRB

Mubea developed the complete process chain for a steel component made of Flexible Rolled Blanks.

Flexible Rollingcoil to coil

hood-typeannealing furnace

stripgalvanizing

Coil Component manufacturing part with differentSheet thicknesses

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Process Chain

Production Technology TRB Pressed Parts Mubea Press Shop Application Example: Steering Link

0,00

1,00

2,00

3,00

4,00

0 100 200 300 400 500 600

Platinenlänge in mmBlank Length in mm

Wal

l Thi

ckne

ssin

mm

Mechanical press,Press force: 1.100 tonnes

Max. length pressed parts: 1450mm Max. length developed blanks:

2500mm

Fully automated part / developed blank production from coil

Fully automated blank orientation(lengthwise or across the rollingdirection), independent of die

In-house processing of Tailor RolledBlanks

Decoiling Cutting Forming PartRotationTransport +

Short processing time: raw material coil to the finished, flexibly rolled component in one plant.

Cost reduction due to omittance of storing and one production step (stackling of blanks).

New Mubea Press Shop

Principle and Status of TRB

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The material and forming properties of Tailor Rolled Blanks are comparable to conventionally rolled metal.

Properties of TRB

• Continuous transition

• Harmonic tension distribution throughout the thickness transition area

• Homogeneous surface

• No disturbed fibre pattern

• No notch effect

• No detrimental effects on microstructure caused by welding

• Can be modelled for simulation

• Forming properties are comparable to conventionally rolled metal

TWB

Analysis of the deep drawing performance

TRB

Source: RWTH Aachen, Institut für Bildsame Formgebung

Tension distribution: Weld seam vs. continuous transition

Forming behaviour

w w w . a u t o s t e e l . o r gEasy contour optimization due to the flexibility of the process.

0,00

0,40

0,80

1,20

1,60

0 200 400 600 800 1000 12000,00

0,40

0,80

1,20

1,60

0 200 400 600 800 1000 1200

contour changes

length in mm

shee

t met

al th

ickn

ess

in m

m

Process flexibility

• The flexible rolling process enables

non tool-related production

• Simple software programming

allows contour changes from one

coil to

the other

• Cost efficient manufacturing of

derivates or product variants

– Without set-up costs

– No additional body shop costs

Features of TRB

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1,851,35

1,00

1,35 1,85

• Front crash demands local up-gauging at load exposed front and below x-member

• Improvement of crash performance

Functional improvement

Side memberCross member

With local sheet metal thickness adaptations to the load Tailor Rolled Blanks provide best performance at minimum weight.

• Part design requires increased thickness

• Optimized distribution of stiffness in outer areas by matching of sheet thickness (NVH)

0,40

0,80

1,20

1,60

0 200 400 600 800 1000 1200length in mm

shee

t met

al th

ickn

ess

in m

m

0,50

1,00

1,50

2,00

0 200 400 600 800 1000length in mm

shee

t met

al th

ickn

ess

in m

m

1,35

1,20

1,00

1,501,00

Features of TRB

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0,50

1,00

1,50

2,00

2,50

0 500 1000 1500 2000

length in mm

shee

t met

al

thic

knes

s in

mm

Integration of components

• Conventional design:1 component4 reinforcements 5 parts

• TRB – design: 1 part

Opportunities:– production costs– tool costs / investments– assembly process– logistic costs– floor space required

• Potential savings up to 1 US$/unit exclusive of weight-increasing

Reduction of assembly groups by Tailor Rolled Blanks.

conventional design

TRB – design

Features of TRB

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The technology offers high potentials for different components in the structure and chassis areas. Application criteria for optimum TRB applications have been identified.

Application Examples

connection member

tunnel reinforcementcross member

seat cross member

rear side member

strut tube

roof bow

front side memberrocker panel

Structure & chassis parts

• Load exposed parts with sufficient thickness for local reductions

• Sub-assemblies with reinforcements

• Weight reduction of 20% and above

• Straight parts with high material utilization from blank to part (below 40%)

• Integration of parts to reduce complexity

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Producing structure parts for the DC E-class and the BMW 5-series,we verified volume production capacity.

TRB Series Applications

• Increased torsional stiffness • Weight reduction of 1,2 kg

vs. conventional part

HSLA 300 / 350 TRB Z100flexible rolled 1,9 > 1,05 > 1,9 mm

1,93

1,93

1,050,8

1

1,2

1,4

1,6

1,8

2

0 200 400 600 800 1000

Platinenlänge in mmB

andd

icke

in m

mStrip length in mm

Stri

p th

ickn

ess

in m

m

Rear cross member

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Considering the technology advantages of TRB during the part development process results in maximal weight reduction and low costs.

TRT Series Applications

0,000,200,400,600,801,001,201,401,601,802,00

0 200 400 600 800 1000 1200 1400

Rohrlänge in mm

Wan

dstä

rke

in m

m

HSLA420 TRBflexible rolled

1.0 > 1.6 > 1.8 > 1.6 > 1.0 > 1.4 > 1.0

• 30% weight reduction• Narrowest part tolerances• Cost-effective light weight

construction

Tube length in mm

Strip

thic

knes

s in

mm

Cockpit cross member

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Mubea put the first production line for Tailor Rolled Tubes in stream.

Tailor Rolled Products

Tube Production Line

Layout tube production line • Discontinuous tube production

• High number of profile shapes by means of flexible forming techniques

• Connection by laser beam welding

• Integration of further process stepslike bending and forming

Tube with a constant outer diameter and invisible thickness transition run

Tube with constant inner diameter and visible thickness transition run

Tube with variable diameters and varying thicknesses

Profile shapes

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Tailor Rolled Tube with variable diameters

Development of Tailor Rolled Tubes (TRT)

Manufacturing tubes with variable diameters and sheet metal thicknesses features maximum flexibility in weight optimization and design.

Diameter variation: 52%Thickness variation: 43%Weight reduction: 33%

Diameter variation: 31%Thickness variation: 50%Weight reduction: 35%

• Different diameters along the whole tube

• Different thicknesses over the whole length

of the tube

• Maximum weight savings

• High degree of design flexibility

• Cost efficient manufacturing of complex tube

geometries (compared to hydro forming)

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Combination of Hot Forming and Flexible Rolling

The combination of matched sheet metal thickness and extremely high material strengths allows a maximal weight reduction.

Coil

Presswith

coolingOvenCoil rolling

levelling, profile cut

Hot fromed TRB

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PM49 B-Pillar

BTR 165 TRBflexible rolled 1.0 > 1.9 > 1.6 > 1.3

• 24% weight reduction• Improved crash performance as a

result of integration of componentsand adaptation of thickness

Weight optimized B-pillar design through load adapted thicknesses.

Rp0.2 [N/mm²] Rm [N/mm²] A5 [%]min. 950 min. 1300 min. 6

die hardened

Hot fromed TRB

0.00

0.50

1.00

1.50

2.00

2.50

0 200 400 600 800 1000 1200 1400 1600 1800

length in mm

shee

t met

al th

ickn

ess

in m

m

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Summary

• Flexible Rolling is designed as a continuous rolling process for metal sheets with periodically varying thickness.

• Mubea developed the complete process chain for a steel component made of Flexible Rolled Blanks.

• The adoption of Tailor Rolled Blanks in the automotive industry offers great potential for the optimization of weight, function, cost and complexity.

• The material and forming properties of Tailor Rolled Blanks are comparable to conventionally rolled metal.

• All conventional process steps for the production of metal parts are applicable for Tailor Rolled Blanks.

• The technology offers high potential for different components in the structure and chassis area.

• Mubea has put the first production line for Tailor Rolled Tubes in stream.

• World-wide, Mubea is leading in the production of Tailor Rolled Products.

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THANK YOU VERY MUCHFOR YOUR ATTENTION!!!!