Hot Forming Introduction
2014.6.16
New features
Thermal thick shells for the tools (TSHELL=1)
Thermal gravity loading simulation
Thermal press hardening simulation
Default friction coefficient for hot forming (0.46)
Initial temperatures for both blanks and tools
Support of *DEFINE_TABLE_3D for *MAT_106/
*MAT_244
Thermal time step for hot forming
Unit system
Basic unit system
Mass
Length
Time
Force
Pressure
Work
or
Energy
Density
Elas:c
modulus
ton
mm
MPa
N
mm
ton/mm^3
MPa
All the units will be converted to basic unit [ton, mm , s, N] in the input deck.
Unit in the GUI
Commonly used unit is provided in the GUI, user does not need to convert
them to the basic unit system manually in the hot forming setup.
Hot forming process
Full processes of hot forming in eta/Dynaform 5.9.2
The stages of gravity loading and press hardening are optional.
Gravity
loading
Hot
forming
Press
hardening
Thermal thick shells
Thermal thick shells for the tools
The heat transfer from blank to the tools is proportional to the temperature
gradient of the contact partners.
The thermal thick shells give us higher accuracy for longer contact times.
This is necessary for the gravity phase and slow tool velocity.
*CONTROL_SHELL
TSHELL=1
*CONTROL_CONTACT
ITHOFF=1
Thermal thick shells
Thermal thick shells for the tools
The artificial thickness can be calculated from the thermal effusivity
Thermal gravity loading
Thermal gravity loading simulation
Since the blank material is very soft at high temperatures, the bending
of the blank during the insertion might be significant. This could affect
the initial blank position before the press hardening process.
The material properties change significantly with the temperature.
During the insertion of the hot blank into the press, some areas of the
blank get in contact with the tools, some do not. In those areas where
contact occurs, the temperature of the blank decreases significantly due
to the cooling of the tools. Thus, the initial temperature distribution in the
blank before the forming stage is NOT uniform.
Thermal friction
Friction
Since there is no lubricant in hot forming, the friction is very high, the
default friction coefficient is 0.46. The user can change this if necessary.
Support of *DEFINE_TABLE_3D
Supports *DEFINE_TABLE_3D for stress/strain
Temperature
Strain rate
Thermal time step
Thermal time step
Thermal time step is higher than the mechanical time step with dynamic
explicit time integration:
TMAX = 1/tool velocity
GUI of hot forming
Hot Forming is a separate module.
GUI of hot forming
The tools of gravity/hardening are
referred to as the tools of forming.
Blank sheet material definition
Blank material definition:
Structural
Thermal
Blank sheet material definition
Select the material type and
define the parameters of the
material.
Structural material
MAT106
*MAT_ELASTIC_VISCOPLASTIC_THERMAL
MAT244
*MAT_UHS_STEEL
Thermal material
1. *MAT_THERMAL_ISOTROPIC
2. *MAT_THERMAL_ORTHOTROPIC
3. *MAT_THERMAL_ISOTROPIC_TD
4. *MAT_THERMAL_ORTHOTROPIC_TD
5. *MAT_THERMAL_ISOTROPIC_PHASE
_CHANGE
6. *MAT_THERMAL_ISOTROPIC_TD_LC
Tool material definition
Select the material type and
define the parameters of the
material.
Structural material
MAT20 *MAT_RIGID
Tool structural material is defined
automatically.
Thermal material
1. *MAT_THERMAL_ISOTROPIC
2. *MAT_THERMAL_ORTHOTROPIC
3. *MAT_THERMAL_ISOTROPIC_TD
4. *MAT_THERMAL_ORTHOTROPIC_TD
5. *MAT_THERMAL_ISOTROPIC_PHASE
_CHANGE
6. *MAT_THERMAL_ISOTROPIC_TD_LC
Contact parameters
Setup the contact parameters for
each tool.
Initial temperature for tools
Setup the initial temperature for
each tool.
Used for all tools All tools have
the same initial temperature.
Boundary condition
The initial temperature of the
blank is defined in the boundary
of the 1st stage.
The temperature information file
*.new_temp_ic.inc will be
included.
User can select Celsius (C) or
Kelvin (K) as the unit of
temperature.
Configuration for hot forming
User can modify the default parameters for hot forming in default config.
