Thermomechanical Processing for Creating Bi-Metal Bearing ... · Die forging ! Impact extrusion ! Cross wedge rolling Use of combined semi-finished workpieces and thermo-mechanical

Spartanburg, South Carolina, June 5-7, 2018

Thermomechanical Processing for Creating Bi-Metal Bearing Bushings

Thermal Processing in Motion

Robert C. Goldstein Bernd-Arno Behrens Anna Chugreeva

© Leibniz Universität Hannover, IFUM, Prof. Dr.-Ing. Bernd-Arno Behrens Seite 2 | Thermal Processing in Motion 2018

!  Introduction and Motivation

!  SFB 1153 Tailored Forming

!  Forming Process Design

!  Results

!  Summary and Outlook

Outline


Introduction and Motivation

Automobile Engines

Otto engine (non-charger)

Otto engine (turbocharger)

Diesel engine

Year

Spe

cific

Out

put,

kW/d

m3

Source: Golloch, 2005 Source: Audi AG 1.8 TFSI Engine

!  Rising output density

!  Locally varying loads

!  Conservation of resources

!  Energy efficiency

!  Integrate different materials into one single bi-material component

!  Take advantage of specific characteristics of different materials

Current Trends Solution approaches


Introduction and Motivation

Turbine Blade

Dental Implant Generator Shaft

mechanical loading

biocompatible surface roughness little weight

mechanical/tribological loading

mechanical loading

thermal loading

Energy Technology

Piston

thermal/mechanical loading

little weight

Automative Engineering Aerospace Engineering

Drive Shaft Yoke

tribological loading

mechanical loading

Automative Engineering Medical Engineering

Appropriate Material at the Appropriate Location

!  Extended functionality of components

!  Lightweight construction


Outline




!  Results



!  Die forging !  Impact extrusion !  Cross wedge rolling

Use of combined semi-finished workpieces and thermo-mechanical manufacturing processes to produce hybrid components with locally-adapted properties

Joining Forming Finishing High-performance components with locally-adapted properties

SFB 1153 Tailored Forming

!  Profile extrusion !  Deposition welding !  Friction welding

!  Machining !  Heat treatment !  Finishing

General Process Chain within the Collaborative Research Centre SFB 1153

!  Service life evaluation !  Geometrical inspection !  Damage prediction !  Multiscale modelling



Stepped Shaft 1 Coaxial Arrangement

of Materials

Bearing Bushing Bevel Gear

Bi-Material Automotive Parts

Stepped Shaft 2 Sequential Arrangement

of Materials



Stepped Shaft 1 Coaxial Arrangement

of Materials

Bearing Bushing Bevel Gear

Bi-Material Automotive Parts

Stepped Shaft 2 Sequential Arrangement

of Materials


Outline




!  Results



Initial and Final Geometry

Ø 63 mm

Aluminum AA-6082

Steel 20MnCr5 84

mm

Ø 64 mm

Ø 32 mm

71 m

m

Ø 30 mm

Ø 62 mm Ø 44 mm

Ø 86 mm

The bi-metal bearing bushing represents a lightweight concept:

!  Combination of steel 20MnCr5 and aluminum 6082

!  Coaxially arranged workpieces were designed in accordance with the final geometry

!  High performance and wear resistant material on the high loaded bearing surface

!  Light aluminum in the structure areas

!  Low weight while maintaining high durability and performance

Bi-Material Workpiece Bearing Bushing

Forming Process Design



Punch

Disc Springs

Closure Plate

Punch Guide

Ejector Stress Ring

Heating Sleeve

Forging Die

Insulation Plate

Forming Tool System

!  Precise positioning of the workpiece by an integrated punch guide

!  Near-net-shape forging

!  Automatic detaching of the forged parts with disc springs’ force

!  Inhomogeneous forming temperature (Steel/Aluminium)



Heating Concept – Induction Coil

!  Dissimilar thermal, physical and mechanical properties of steel and aluminum

!  Reaching of material specific forming temperatures for both material is required

!  Targeted presetting of temperature gradients by induction heating in order to increase the formability

!  Maximum temperature of steel is limited due to the melting temperature of aluminum

!  Improvement of the heating efficiency by magnetic flux controller

42 m

m 6 m

m 10

mm

1 2 Steel-Aluminum Workpiece

Magnetic Flux Controller

Induction Coil

Position of Thermocouples: 1 - TAluminum 2 - TSteel

Steel-Aluminum Workpiece

Induction Coil

Workpiece Table

Ceramic Tube Around Coil



Heating Concept – Effect of Magnetic Flux Controller

Steel

Aluminum

Without Alphaform®

With Alphaform®

Heating Parameter Without Alphaform®

With Alphaform®

Output Voltage, V 600 300 Set Voltage, % 60 100 Heating Time, s 60 10

Aluminum R26,5

R19 Steel

0

100

200

300

400

500

600

0 10 20 30 40 50 60 70 80

Temperature Curves

Time, s

Tem

pera

ture

, °C

Measurement Points

Dimensions mm

Outer Diameter Aluminum 62 Outer Diameter Steel 44 Inner Diameter Steel 32

!  Using of magnetic flux controller lead to shorter heating time with less power


Outline




!  Results



Results

Numerical Modelling of the Heating Process

Simulation

Experiment

0

100

200

300

400

500

600

700

800

900

0 20 40 60 80 100

TSteel

TAluminum

Time, s

Tem

pera

ture

, °C

Comparison between Experiment and Simulation with ideal contact

!  Both curves equalize at the same temperature

!  The total energy input was the same for both cases

!  The shrink-fitted workpieces have not perfect contact " higher temperature gradients possible


Results


150

200

250

300

350

400

450

500

550

600

4 6 8 10 12 0

100

200

300

400

500

600

700

800

900

0 5 10 15 20

TSteel

TAluminum

13 s

14 s

12 s

11 s

10 s

Heating time:

Time, s

Tem

pera

ture

, °C

Tem

pera

ture

, °C

Time, s

Line 1: y = 52,56x – 0,5202 Line 2: y = 60,157x – 427,22

Line 1

Line 2

A: Point of contact conditions change A

TSteel

TAluminum

!  The aluminum has a higher thermal expansion coefficient compared with steel

!  The gap between steel and aluminum grows with increasing temperature

!  The heat exchange decreases due to less contact

Experimentally measured temperature curves


Results


!  Integration of a thin layer with temperature dependent conduction properties between steel and aluminum in simulation model

!  Slight deviations at the beginning and the end of the heating process are caused by thermal lag of the thermocouples

Comparison between Experiment and Simulation with variable power and conductivity of the gap

0

100

200

300

400

500

600

700

800

900

0 5 10 15 20 25 30 Time, s

Tem

pera

ture

, °C

Simulation

Experiment

TSteel

TAluminum

Rad

ius,

mm

0 2 4 6 8 10 12 14 16 18 20 22 24

16

18

20

22

24

26

28

30

32

Time, s

Temperature, °C 850 800

50

750 700 750 600 550 500 450 400 350 300 250 200

100 150

Radial temperature distribution dependent on heating time

Ste

el

Alu

min

um

Heating


Results


300

450

600

750

900

15 20 25 30

Tem

pera

ture

, °C

Radius, mm

a) Heating time 11 s

After heating

After transportation (6s)

300

450

600

750

900

15 20 25 30

Tem

pera

ture

, °C

300

450

600

750

900

15 20 25 30 Te

mpe

ratu

re, °

C

Radius, mm Radius, mm

b) Heating time 13 s c) Heating time 14 s

Steel Aluminum Steel Aluminum Steel Aluminum

R

Radial temperature distribution in bi-metal workpieces

Used for the Forming Tests


Results

Experimental Forming Tests


Results

Experimental Forming Tests

Heating strategy 1

EN AW-6082

20MnCr5

EN AW-6082

20MnCr5

Intermetallic Phase

Heating time 13 seconds

Transportation time 6 seconds

TSteel Approx. 717 °C

TAluminum Approx. 458 °C

Bonding quality Form-/ Force-closed joint

Heating strategy 2

Heating time 14 seconds

Transportation time 6 seconds

TSteel Approx. 719 °C

TAluminum Approx. 492 °C

Bonding quality Partially

metallurgical bonding


Outline




!  Results



Outlook

Summary

Summary and outlook

!  Forming of dissimilar materials is challenging due to their different material-specific properties

!  By using of tailored heating, high forming strains can be achieved in steel-aluminum workpieces

!  The forming temperature have the most influence on the resulting bonding quality

Mechanical characterization of the bonding quality by push-out test

For further improving of bonding quality, an optimization of the heating process is required:

!  Targeted cooling of aluminum surface during the induction heating (water spray field, water-cooled robot gripper)

!  Reduction of the transportation time

!  Application of the induction generator with higher power

Pusher Plug

Steel Aluminum

F

Base Plate

Cross section of push-out test arrangement


Thank you for your attention!

The presented results were obtained within the Collaborative Research Centre 1153 ‘‘Process chain to produce hybrid high performance components by Tailored Forming’’. The speaker would like to thank German Research Foundation (DFG) for the financial and organisational support of this project.

www.sfb1153.uni-hannover.de

Contact us!

Robert C. Goldstein [email protected]

Anna Chugreeva [email protected]

Documents

Thermomechanical Processing for Creating Bi-Metal Bearing ... · Die forging ! Impact extrusion ! Cross wedge rolling Use of combined semi-finished workpieces and thermo-mechanical