Case study: variable adjustment of inner diameter (1)

Established within the GROWTH project GRD1-1999-10748 "Improvement of Service Life and Reliability of Cold Forging Tools with respect to Fatigue Damage due to Cyclic Plasticity (COLT)", funded by the European Community.

COLT Design Manual for Cold Forging Dies

Case study: net-shape forging in close tolerancesCase study: net-shape forging in close tolerancesby STRECONby STRECON®® VARI-FIT VARI-FIT

Example for net-shape forgedspline on hollow steering shaft

Model of a STRECON® VARI-FIT

Case study: variable adjustment of inner diameter (2)

Established within the GROWTH project GRD1-1999-10748 "Improvement of Service Life and Reliability of Cold Forging Tools with respect to Fatigue Damage due to Cyclic Plasticity (COLT)", funded by the European Community.

COLT Design Manual for Cold Forging Dies

Principle design of a STRECONPrinciple design of a STRECON®® VARI-FIT VARI-FIT

die insert

carbidewinding core

stripwinding

intermediaterings

axial prestressing

• Strip-wound container withcarbide winding core

• Combined radial and axial prestressing

• Change of the inner diameter of the die by controlled axial displacement of the die

• Intermediate rings define the axial position of the die

• Quick disassembly and assembly for rearrangement of the intermediate rings

lowest position maximum diameter

highest position minimum diameter

Case study: variable adjustment of inner diameter (3)

Established within the GROWTH project GRD1-1999-10748 "Improvement of Service Life and Reliability of Cold Forging Tools with respect to Fatigue Damage due to Cyclic Plasticity (COLT)", funded by the European Community.

COLT Design Manual for Cold Forging Dies

Example:

Inner diameter of the die insert: Ø28mm

Die insert material: WC or HSS

prestressed by STRECON® VARI-FIT

die made of high-speed steel:circa 3 µm diameter change per 0.1 mm axial displacement

die made of carbide:circa 2 µm diameter change per 0.1 mm axial displacement

Variable adjustment of the inner diameter of the dieVariable adjustment of the inner diameter of the die

Case study: variable adjustment of inner diameter (4)

Established within the GROWTH project GRD1-1999-10748 "Improvement of Service Life and Reliability of Cold Forging Tools with respect to Fatigue Damage due to Cyclic Plasticity (COLT)", funded by the European Community.

COLT Design Manual for Cold Forging Dies

Turning

Heat Treatment

Grinding

EDM

Polishing

Coating

Serial productionand on-going inspection

no

in case of conventional prestressing

systems

nono

no

in case of STRECON®

VARI-FIT

Shortening the Shortening the process chain of process chain of manufacturing andmanufacturing andset-up of dies byset-up of dies bySTRECONSTRECON®® VARI-FIT VARI-FIT

OK?

Prestress-Assembly

Tool set-up in the press

Forging and inspection ofsamples

OK?