Dynaform Hot forming introduction

• 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 t

Hot Forming Introduction

2014.6.16

•  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

New features

•  Basic unit system

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

Unit system

modulus

Hot forming process Full processes of hot forming in eta/Dynaform 5.9.2

The stages of gravity loading and press hardening are optional

•  Thermal thick shells for the tools

Thermal thick shells

*CONTROL_SHELL

TSHELL=1

*CONTROL_CONTACT

ITHOFF=1

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

•  Thermal thick shells for the tools

Thermal thick shells

The artificial thickness can be calculated from the thermal effusivity

•  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 gravity loading

•  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

Thermal friction

•  Supports *DEFINE_TABLE_3D for stress/strain

Support of *DEFINE_TABLE_3D

Temperature

Strain rate

•  Thermal time step

Thermal time step is higher than the mechanical time step with dynamic

explicit time integration:

Thermal time step

TMAX = ​1/tool  velocity 

Hot Forming is a separate module

GUI of hot forming

•  The tools of gravity/hardening are referred to as the tools of forming GUI of hot forming

Blank material definition:

•  Structural

•  Thermal

Blank sheet material definition

Select the material type and define the parameters of the material

Structural material

*MAT_ELASTIC_VISCOPLASTIC_THERMAL

*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

Blank sheet 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

Tool material definition

Setup the contact parameters for each tool

Contact parameters

Setup the initial temperature for each tool

Used for all tools – All tools have the same initial temperature

Initial temperature for tools

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

Boundary condition

User can modify the default parameters for hot forming in default config

Configuration for hot forming