BENTELER Mechanical Engineering

BENTELER Mechanical Engineering
Advanced Design of Continuous Furnace
for Hot Stamping Line
Agenda

Introduction BENTELER Group

Furnace design

Heating concept

Dew point regulation
 Contact
Agenda

Introduction BENTELER Group

Furnace design

Heating concept

Dew point regulation
 Contact
Global Engineering Expertise
WE TAKE CUSTOMER
ACCESSIBILITY SERIOUSLY
BENTELER is a globally
active enterprise, with 170
plants, branch offices, and
firms in 38 countries. For
us, in-depth communication
with our business partners
and quick decisions are two
things that go hand in hand.
This is why we are in close
proximity to our customers,
to support them as an
expert development partner
and a reliable supplier.
Our Employees
BENTELER AUTOMOTIVE
Product Groups and Business Areas
STRUCTURES
Structural components and
full-service partner for the
product development and
implementation
CHASSIS & MODULES
Multi-Material-Solutions
out of Steel, Aluminium
and fibre-reinforced
plastics
ENGINE & EXHAUST
SYSTEMS
Systems and components
for heat exchange, fuel
distribution as well as a
focus on the „hot end“ of
the exhaust system
BENTELER-SGL
Total solutions of fibercomposite components,
from the initial design to
series production
MECHANICAL ENGINEERING
Innovative machines and
systems as well as tools for
the automotive industry
DEFENSE
Complex protective
systems for vehicles
Overview of the Product Groups
•
•
•
•
Chassis
Modules
Structures
Engine and Exhaust
Systems
BENTELER MECHANICAL ENGINEERING
Our Structure
BENTELER International AG
BENTELER Deutschland GmbH
BENTELER
Automotive
BENTELER
Mechanical Engineering
BENTELER
Steel/Tube
BENTELER
Distribution
BENTELER
Engineering
BENTELER
Glass Processing
Equipment
Our Locations
Bielefeld, Germany
Production
Liberec, Czech Republik
Production
Fort Wayne, USA
Bangalore, India
Agenda

Introduction BENTELER Group

Furnace design

Heating concept

Dew point regulation
 Contact
Hot Forming Technology – Furnace Design
LOADING
HEATING
Z1
INPUT-CONVEYOR
Z2
Z3
Z4
Z5
STAMPING
Z6
Z7
Z8
FURNACE
General layout example for a Hot Forming Line
OUTPUT-CONVEYOR
Hot Forming Technology – Furnace Design
Homogenous furnace
Partial furnace
Hot Forming Technology – Furnace Design
Special features:
•
Modular Concept
•
Expandable
•
Easy installation
•
Easy maintenance
•
Easy usage
• Modular design
• Comfortable access
• Effective safety concept
• All process parameters in recordable prescriptions
(recipes)
Hot Forming Technology – Furnace Design
• Easy Installation
― Pre assembled and installed modular
design
― Insulation installed inclusive rollers
― Cable connections are provided with
connectors
― Transport by standard containers or
trucks
― Without welding during installation
― Installation / assembly to first heating
up: 30 days
― SOP: 10 days after first heating up
Agenda

Introduction BENTELER Group

Furnace design

Heating concept

Dew point regulation
 Contact
Hot Forming Technology – Heating Concept
Example of burner efficiency
Hot Forming Technology – Heating Concept
Radiation heat transfer – Basic equations
• Calculation of radiation energy flux using Stefan-Boltzmann law
• Equation if energy flux for non-black bodies
e(T)= 𝝈𝜺(𝑻𝟒 )
𝝈 = 5.6707e-8 (W∙m-2ˑK-4) - Stefan-Boltzmann constant
𝜺 - Emissivity
T(K) - thermodynamic temperature
• Total net heat flux between bodies (1) and (2) that are non-black (simplified)
𝑸𝟏−𝟐 = 𝑨𝟏 𝝈𝑭𝟏−𝟐 (𝑻𝟏𝟒 − 𝑻𝟐𝟒 )
𝑨 𝒎2 - Surface
𝑭𝟏−𝟐 - Transfer factor
Hot Forming Technology – Heating Concept
Stefan - Boltzmann equation
Blank
930°C
Simplified for gray object in a large
isothermal environment.
900°C
𝑸𝟏−𝟐 = 𝑨𝟏 𝝈𝜺𝟏 (𝑻𝟏𝟒 − 𝑻𝟐𝟒 )
600°C
Radiation
Radiation vs. Convection
Temperature of furnace [°C]
870
900
920
930,0
Temperature of blank [°C]
25
600
900
920,0
Emissivity
0,38
0,12
0,54
0,7
Convection coefficient[W/m2K]
9,0
9,0
9,0
9,0
Heat flux radiation [kW/m2]
36,6
8,9
4,1
2,7
Heat flux convection [kW/m2]
7,6
2,7
0,18
0,09
Ratio between
4,8
13,3
22,8
29,4
Conduction
Convection
0%
50%
50°C
100% Ratio
Temperature of 930°C inside the furnace
Hot Forming Technology – Heating Concept
Radiation heat transfer – FEM Analysis
Hot Forming Technology – Furnace Design
Radiation heat transfer into the blank
Hot Forming Technology – Furnace Design
Furnace Design – thermal simulation of furnace openings
(input and output)
Hot Forming Technology – Furnace Design
Temperature distribution inside the furnace input
Agenda

Introduction BENTELER Group

Furnace design

Heating concept

Dew point regulation
 Contact
Hot Forming Technology – Dew Point Regulation
• Hydrogen embrittlement
― Hydrogen embrittlement is the process by which various metals,
most importantly high-strength steel, become brittle and
fracture following exposure to hydrogen
― Basic chemical reactions during embrittlement process for
uncoated blanks are:
3Fe + 4H2 O → Fe3 O4 + 8H
Fe + H2 O → FeO + 2H (from 570°C)
― Elemental hydrogen diffuses along the grain boundaries inside
the steel structure.
― Formed molecular hydrogen and methane gas builds up
enormous pressures that initiate cracks.
― This is quite important in case of hot formed parts which have
martensitic structure and also contains rest strain from the
forming process.
Hot Forming Technology – Dew Point Regulation
• Hydrogen embrittlement
―
Situation is dangerous especially for coated materials (eg. AlSi) from two reasons.
―
First: the hydrogen can be easily locked under the coating.
―
Second: Al – Si coating also react with water by high
temperature.
―
Basic chemical reactions for Al – Si coated blanks are:
2Al+6H_2 O→2Al(OH)+6H
2Al+4H_2 O→2AlO (OH)+6H
2Al+3H_2 O→Al_2 O_3+6H
Si+〖2H〗_2 O→SiO_2+4H
―
Described processes are running above 200°C, but really
dangerous from 550°C – 650°C due to short d-well time
inside the furnace.
Hot Forming Technology – Dew Point Regulation
• Possible sources causing Hydrogen embrittlement inside the furnace
―
Endo – Exo gas protective atmosphere inside the furnace (H2, CO, N2, CO2, H2O)
―
Nitrogen + natural gas mixture inside the furnace (CH4, CO, N2, CO2, H2O)
―
Open flame inside the furnace (N2, CO2, H2O, CO)
―
Missing controlled atmosphere (N2, CO2, H2O)
• Nowadays, only the parts produced under the controlled atmosphere with
reduced dew point temperature to -10°C level and lower are accepted by
most of the OEM’s.
• BENTELER furnaces have the dew point regulation system in standard basic
configuration.
Hot Forming Technology – Dew Point Regulation
• Key features
― Avoiding the water vapor inside the furnace –
prevent hydrogen embrittlement on the parts
― Based on using of dried air or pure nitrogen
― Process automatically controlled via PLC
― Fits all CQI9 requirements
― Possible system operation with coated and also
uncoated blanks.
― Dew point after air dryer is approx. - 40°C
― Implementation of 2 - 6 measurement points, 2 –
4 regulation zones
― Using of high reliable polymer dew point sensors or
laser moisture analyzer like high end solution
Hot Forming Technology – Dew Point Regulation
BENTELER has developed and patented the Dew Point Regulation in 2011
Agenda

Introduction BENTELER Group

Furnace design

Heating concept

Dew point regulation
 Contact
CONTACT DETAILS
Jad John Tawk
Global Sales Manager
Dr.-Ing. Borek Dvorak
Engineering Manager
AT Design
BENTELER Maschinenbau GmbH
Frachtstrasse 10–16
33602 Bielefeld
Germany
Benteler Maschinenbau CZ s.r.o.
Hodkovicka 981/42
460 06 Liberec
Czech Republic
Phone: +49 521 542-170
Phone: +420.482 465 327
[email protected]
www.benteler-maschinenbau.de
[email protected]
www.benteler.cz