Fraunhofer Institute for Machine Tools and Forming Technology
Fraunhofer Institute for Machine Tools and Forming Technology

Hydroforming of tubes and profiles

The hydroforming process (HF) uses internal pressure acting in all directions to force closed profiles against a die cavity, thus forming them in a controlled manner. The forming dies usually consist of an upper part and a bottom part with a corresponding parting plane. The active medium is introduced via axial sealing punches, which use axial pressure to reliably seal off the component from the environment. Depending on the component shape and sealing concept, additional material can also be forced into the forming zone in order to extend the range of component shapes that can be geometrically realized. This process makes it possible to produce unique component geometries that are impossible or extremely complex to produce using other production processes.

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HF at room temperature

In spite of the increasing relevance of tempered forming processes, conventional hydroforming at room temperature still makes up the main field of industrial activity where the predominant range of components is established.  The following research projects demonstrate that technological limits can be tested using this conventional method.

  • Metal blades for vertical-axis wind turbines
  • Crash-activated headrest frame
  • Designer goods /bionic structures: chair “hydra”
  • Lightweight camshaft
  • Process combination: sheet forming or tube forming combined with plastic injection molding
  • Concept for car B-pillars
  • Hydroformed distribution beam

Tempered HF

Complex HF components are often produced in several forming stages with intermediate annealing processes. However, these multi-stage process chains are very cost-intensive and error-prone.  Tempered forming is a possible approach for shortening the process chain. Depending on the material used, the forming properties can be significantly improved at increased temperatures. Gaseous active media such as nitrogen are used due to forming temperatures of up to 1,100°C. Tempered hydroforming is also called hot metal gas forming (HMGF).

  • Forming of multi-chamber profiles
  • Manufacturing of very small and very large components
  • Integration of various additional processes (e.g. punching, flange forming, manufacturing of notches in headrest frame)
  • Realization of super high strength components by HF press hardening
  • Manufacturing of metal-plastic hybrid components by using the process combinations of HF injection molding as well as deep drawing, injection molding and forming with the melt
  • Isothermal tempered forming of light metals (aluminum, magnesium and titanium)

Development of process chains

  • Market analysis
  • Investigation of process chains
  • Process optimization
  • Cost-benefit calculation        
  • Development and realization of manufacturing concepts
  • Planning and technological dimensioning of processes, tools and machines

Development and evaluation of forming strategies

  • Market analysis
  • Feasibility studies
  • Technology development
  • Development of characteristic process values and optimal forming strategies
  • Benchmarking
  • Numerical simulation
  • Manufacturing of prototypes

Quality assurance

  • Process monitoring and control

Machine technology

  • HF press DUNKES HS3-1500 (max. closing force: 15,000 kN; max. active media pressure: 120 MPa (gas) or 700 MPa (HFA fluid))
  • HF press Schuler SHP 50000 (max. closing force: 50,000 kN; max. active media pressure: 120 MPa (gas) or 400 MPa (HFA fluid))
  • Peripherals (system for induction heating, chamber furnaces, robots, 10 kW cooling unit and electrical die heating)

Software

  • CAD: Catia V5, PTC Creo, Inventor
  • FEM simulation: Autoform, PamStamp, LS Dyna, Abaqus, Deform, Ansys

Testing technology

  • Coordinate measuring instrument PRISMO7S-ACC (ZEISS)
  • Various optical and contact measuring devices for roughness and profiles
  • White light interferometer, ITO Stuttgart University
  • Confocal microscope, ITO Stuttgart University
  • Scanning electron microscope, LEO Oberkochen; stereomicroscope
  • EDX system, Oxford Instruments
  • Optical measuring station UBM
  • Form measuring instrument F2002, HOMMEL
  • Ultrasonic wall thickness gauges
  • Profile projector PJ300