U.S. patent application number 13/901828 was filed with the patent office on 2013-11-28 for furnace and method of operating the furnace.
This patent application is currently assigned to Benteler Automobiltechnik GmbH. The applicant listed for this patent is Benteler Automobiltechnik GmbH. Invention is credited to Jochem Grewe.
Application Number | 20130313763 13/901828 |
Document ID | / |
Family ID | 48366212 |
Filed Date | 2013-11-28 |
United States Patent
Application |
20130313763 |
Kind Code |
A1 |
Grewe; Jochem |
November 28, 2013 |
FURNACE AND METHOD OF OPERATING THE FURNACE
Abstract
Light metal components and/or plates are transported through a
furnace in a clocked or continuous transport process and heated and
optionally cooled inside the furnace by an air or gas flow. For
this purpose, a continuous air-/gas circulation is generated,
wherein circulating air-/gas flow flows across the light metal
components and/or plates, heating and cooling them as necessary.
The light metal components and/or plates entering into or exiting
from the furnace perform a sealing function and prevent the
air-/gas flow circulating in the furnace from escaping from the
furnace.
Inventors: |
Grewe; Jochem; (Salzkotten,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Benteler Automobiltechnik GmbH |
Paderborn |
|
DE |
|
|
Assignee: |
Benteler Automobiltechnik
GmbH
Paderborn
DE
|
Family ID: |
48366212 |
Appl. No.: |
13/901828 |
Filed: |
May 24, 2013 |
Current U.S.
Class: |
266/44 ;
266/252 |
Current CPC
Class: |
F27D 99/0073 20130101;
F27D 99/007 20130101; C21D 9/0006 20130101; F27B 9/3005 20130101;
F27B 9/20 20130101; F27B 9/24 20130101 |
Class at
Publication: |
266/44 ;
266/252 |
International
Class: |
C21D 9/00 20060101
C21D009/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 25, 2012 |
DE |
10 2012 104 537.2 |
Claims
1. A furnace for thermal treatment of light metal components which
are continuously transported through the furnace, the furnace
comprising: a heat source, a conveyor transporting the light metal
components through the furnace in a transport direction, and a
blower producing an airflow circulating inside the furnace, wherein
the airflow heats the light metal components inside the furnace by
convection, and a light metal component entering the furnace and a
light metal component exiting from the furnace are constructed as a
barrier so as to hinder the airflow from escaping from the
furnace.
2. The furnace of claim 1, wherein the heat source is constructed
as at least one of an electric heater and a fuel-fired heater.
3. The furnace of claim 1, wherein the blower is arranged inside
the furnace.
4. The furnace of claim 1, wherein the furnace comprises sealing
elements arranged at an entrance or exit of the furnace proving a
thermal seal.
5. The furnace of claim 4, wherein the sealing elements are
constructed as exchangeable shaped baffles.
6. The furnace of claim 1, wherein the furnace comprises at least
two temperature zones, with the light metal components providing a
barrier between the at least two temperature zones.
7. The furnace of claim 6, wherein exchangeable shaped baffles are
disposed at a respective transition between the at least two
temperature zones.
8. The furnace of claim 7, wherein the shaped baffles have an
opening that corresponds substantially to a transverse
cross-sectional frame area of the light metal components orthogonal
to the transport direction.
9. The furnace of claim 1, wherein the furnace comprises a drying
zone disposed in a region of an entrance of the furnace.
10. The furnace of claim 1, wherein the furnace comprises a cooling
zone disposed in a region of an exit of the furnace.
11. The furnace of claim 1, wherein the circulating airflow flows
across a surface of the light metal components when passing through
the furnace.
12. The furnace of claim 6, wherein the circulating airflow flows
across a surface of the light metal components in the at least two
temperature zones with at least one of mutually different air
temperatures and mutually different flow velocities.
13. The furnace of claim 1, wherein the conveyor belt is a chain
conveyor.
14. The furnace of claim 1, wherein the light metal components are
heated to a temperature between 200.degree. C. and 450.degree.
C.
15. A method for thermal treatment of light metal components in a
furnace, wherein the light metal components are continuously
transported through the furnace, the method comprising: placing a
plurality of consecutively arranged light metal components on a
conveyor belt, transporting the light-metal components through the
furnace, wherein an entrance opening at an entrance region of the
furnace is sealed by a light-metal component passing through the
entrance opening, generating a continuously circulating warm
airflow and overflowing the light metal components in at least one
temperature zone inside the furnace with the airflow to thermally
treat the light-metal components, while the light metal components
are continuously transported through the furnace, and discharging
the heat-treated light metal components from the furnace at an exit
of the furnace, wherein an exit opening at an exit region of the
furnace is sealed by light metal component passing through the exit
opening.
16. The method of claim 15, further comprising selecting at least
one of a flow rate of the airflow and an air temperature in the at
least one temperature zone for heating the light metal
components.
17. The method of claim 15, further comprising transferring the
light metal components to an additional treatment process in a
cycle time of less than 15 seconds.
18. The method of claim 15, wherein the light metal components are
dried in the drying zone to remove a lubricant.
19. The method of claim 15, wherein the light metal components are
cooled in a cooling zone to an age-hardening temperature.
20. The method of claim 15, wherein shaped baffles are exchanged in
dependence of the light metal components to be treated.
21. A furnace for thermal treatment of light metal components which
are continuously transported through the furnace, the furnace
comprising: a heat source, a conveyor transporting the light metal
components through the furnace in a transport direction, a blower
producing an airflow circulating inside the furnace, wherein the
airflow heats the light metal components inside the furnace by
convection, and partition walls arranged on the conveyor at mutual
distances between the partition walls, wherein at least one light
metal component is arranged between two partition walls.
22. The furnace of claim 22, wherein at least two temperature zones
having mutually different temperatures are formed inside the
furnace.
23. The furnace of claim 22, wherein the partition walls are
constructed as a barrier to prevent the airflow from escaping from
the furnace when a partition wall passes at least one of an
entrance, an exit and a transition between the at least two
temperature zones.
24. The furnace of claim 23, wherein two successive partition walls
produce a continuous seal at at least one of the entrance, the exit
and the transition.
25. The furnace of claim 21, wherein two or more light metal
components are arranged between two partition walls.
26. The furnace of claim 21, wherein the partition walls on the
conveyor are exchangeable.
27. The furnace of claim 21, wherein the conveyor is a chain
conveyor or a conveyor belt.
28. The furnace of claim 27, wherein the partition walls are
configured for placement on the chain conveyor before an entrance
of the furnace and for removal from the chain conveyor after an
exit of the furnace.
29. The furnace of claim 21, wherein the airflow is guided by the
partition walls and flows across a surface of the light metal
components.
30. The furnace of claim 22, wherein a partition wall separates two
different air flows in two different temperature zones.
31. The furnace of claim 21, wherein the partition walls are
arranged on the conveyor at an angle between 10 degrees and 80
degrees.
32. The furnace of claim 21, wherein the partition walls are
arranged on the conveyor at an angle between 20 and 70 degrees.
33. The furnace of claim 21, wherein the partition walls are
arranged on the conveyor at an angle between 30 and 60 degrees.
34. The furnace of claim 21, wherein the partition walls are
arranged on the conveyor at an angle between 40 and 50 degrees.
35. A method of operating a furnace for thermal treatment of light
metal components, wherein the light metal components are
continuously transported through the furnace on a conveyor belt,
the method comprising: arranging on the conveyor belt partition
walls separating mutually different temperature zones, placing at
least one light-metal component on the conveyor belt between two
partition walls, and transporting the at least one light-metal
component through the furnace.
36. The method of claim 35, wherein two consecutively arranged
partition walls seal at least one of an entrance region, an exit
region and a transition region separating the different temperature
zones, thereby hindering an airflow circulating in the furnace from
escaping from the furnace or crossing over between the different
temperature zones.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application claims the priority of German Patent
Application, Serial No. 10 2012 104 537.2, filed May 25, 2012,
pursuant to 35 U.S.C. 119(a)-(d), the content of which is
incorporated herein by reference in its entirety as if fully set
forth herein.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to a furnace for the thermal
treatment of light metal component, and to a method for the thermal
treatment of light metal components.
[0003] The following discussion of related art is provided to
assist the reader in understanding the advantages of the invention,
and is not to be construed as an admission that this related art is
prior art to this invention.
[0004] The use of sheet metal components for the production of
automotive components has been known for many decades. The sheet
metal components are first formed and then combined to single
modules or to an entire body. Motor vehicle bodies are nowadays
mostly formed as self-supporting bodies, so that the sheet metal
components not only perform aesthetic or shaping tasks, but must
also have stiffness properties to impart to the vehicle body
sufficient rigidity during use.
[0005] Demands on the crash behavior are also placed on the
structural vehicle components, which must dissipate impact energy
into deformation energy through targeted deformation in the event
of a collision.
[0006] Steel represents a preferred material due to its
advantageous manufacturability accompanied by high rigidity. In
particular, the hot-forming and press hardening technology gives
the steel high-strength or even ultra-high-strength properties, so
that the specific weight of the components could be further
reduced, while simultaneously increasing the strength values.
[0007] Today, however, not only aesthetic and safety expectations
are imposed on motor vehicles, but also ecological and economic
aspects for operating the motor vehicle have become rather
important. So it is especially important that the vehicle has low
fuel consumption with simultaneously low CO.sub.2 emissions. For
this purpose, there are various approaches, for example the use of
new drive techniques such as the hybrid drive, or a particular
shape giving the motor vehicle a low air resistance.
[0008] Another approach is the use of light metal components to
reduce the specific weight of the vehicle body and thus of the
entire vehicle. In particular, light metal components made from
aluminum alloys are used.
[0009] For certain applications, for example with high degrees of
deformation or when setting specific strength values in aluminum
components, the plates must be thermally treated prior to forming
and/or at intermediate steps during forming and/or after
forming.
[0010] Continuous furnaces known in the art include a transport
system on which sheet metal components or sheet metal plates are
continuously transported through a furnace and heated inside the
furnace. Several approaches exist, for example infrared heating or
induction heating of the component or the plate inside the
furnace.
[0011] However, when such furnaces are used for light metal alloys,
some methods are inefficient because the aluminum reflects, for
example, the heat radiation or the methods are technically
impractical, since e.g. the shaped plates or components can only be
heated unevenly and thus severely distort; more often, however, the
methods are inefficient, because a large part of the input energy
is not used. Another disadvantage is the high space requirements of
most facilities.
[0012] The furnaces can thus only be operated inefficiently, which
further increases the production costs of the alloy material which
is anyway more expensive compared with steel.
[0013] It would therefore be desirable and advantageous to obviate
prior art shortcomings and to provide an improved furnace for
thermal treatment of light metal components, and an improved method
of operating the furnace capable of cost-effective and efficient
mass production of light metal components.
SUMMARY OF THE INVENTION
[0014] According to one aspect of the present invention, a furnace
for thermal treatment of light metal components which are
continuously transported through the furnace, includes a heat
source, a conveyor transporting the light metal components through
the furnace in a transport direction, and a blower producing an
airflow circulating inside the furnace. The airflow heats the light
metal components inside the furnace by convection, and a light
metal component entering the furnace and a light metal component
exiting from the furnace are constructed as a barrier so as to
hinder the airflow from escaping from the furnace.
[0015] According to another aspect of the invention, a furnace for
thermal treatment of light metal components which are continuously
transported through the furnace, includes a heat source, a conveyor
transporting the light metal components through the furnace in a
transport direction, a blower producing an airflow circulating
inside the furnace, wherein the airflow heats the light metal
components inside the furnace by convection, and partition walls
arranged on the conveyor at mutual distances between the partition
walls. At least one light metal component is arranged between two
partition walls.
[0016] According to another aspect of the present invention, a
method for thermal treatment of light metal components in a
furnace, wherein the light metal components are continuously
transported through the furnace, includes placing a plurality of
consecutively arranged light metal components on a conveyor belt,
transporting the light-metal components through the furnace,
wherein an entrance opening at an entrance region of the furnace is
sealed by a light-metal component passing through the entrance
opening, generating a continuously circulating warm airflow and
overflowing the light metal components in at least one temperature
zone inside the furnace with the airflow to thermally treat the
light-metal components, while the light metal components are
continuously transported through the furnace, and discharging the
heat-treated light metal components from the furnace at an exit of
the furnace, wherein an exit opening at an exit region of the
furnace is sealed by light metal component passing through the exit
opening.
[0017] According to yet another aspect of the present invention, a
method of operating a furnace for thermal treatment of light metal
components, wherein the light metal components are continuously
transported through the furnace on a conveyor belt, includes
arranging on the conveyor belt partition walls separating mutually
different temperature zones, placing at least one light-metal
component on the conveyor belt between two partition walls, and
transporting the at least one light-metal component through the
furnace.
[0018] With the airflow circulating in the furnace, only the energy
dissipated on the plate or the component or energy occurring as
lost flows needs to be replenished, wherein the alloy components
can be heated in the furnace by convection by the airflow and a
respective light metal component entering the furnace and a
respective light metal component exiting the furnace can act as a
barrier and prevent the airflow from escaping from the furnace.
[0019] The furnace according to the invention uses convection for
the thermal treatment, especially for heating the light metal alloy
components. A light metal component within the context of the
invention may be an already formed component, but also a component
and an intermediate stage, or even a plate, which is transformed
subsequent to the thermal treatment.
[0020] Advantageously, light metal components made of an aluminum
alloy, in particular made of a wrought aluminum alloy, may be
treated with the furnace according to the invention. The respective
components may be placed on a clocked or continuously operating
conveyor, and may then enter the furnace evenly spaced in single
file, and preferably at regular intervals separated by additional
pressure-seal baffles. The furnace is thus constructed at an
entrance so that a light metal component entering the furnace and a
light metal component exiting the furnace operate as a barrier, so
that the airflow circulating within the furnace does not escape
from the furnace. At each transition from a component located in
the entrance region to the next component entering the entrance
region, and likewise at the exit of the furnace, losses occur due
to the separation between the individual components. In addition,
overflow losses also occur at a gap between the component or
barrier and the adjacent terminations. Because a number of
components can be transported over a short distance through the
furnace either in a clocked or continuous fashion, particularly
short cycle times of a few seconds can be realized so that the
furnace can effectively handle large quantities of light metal
alloys for thermal treatment.
[0021] According to an advantageous feature of the present
invention, the components to be heated may be transported
continuously, without any interruption. Accordingly, components may
be continuously placed onto the conveyor belt at the entrance of
the furnace, transported through the furnace and again removed from
the transporters at the exit of the furnace.
[0022] According to another advantageous feature of the present
invention, the continuous transport may also cooperate with
upstream and downstream production systems commensurate with the
production cycle. For example, the conveyor belt may be briefly
stopped each time a new component is added and then possibly also
when at the same time a heated component is removed at the exit of
the furnace and then restarted, until the next component.
[0023] According to another advantageous feature of the present
invention, the transport speed of the components through the
furnace may not only be selected as a function of the residence
time of the components inside the furnace itself, but may also be
adapted to the production process such that a sufficient quantity
of heat-treated components is always provided for further
processing.
[0024] Inside the furnace according to the invention, one or more
heat sources may be arranged to generate at least a predetermined
temperature. This temperature is advantageously a temperature
between 100.degree. C. and 600.degree. C., which then produces with
a circulation system, in particular an air circulation system
arranged inside the furnace, in conjunction with a duct system
formed in the furnace, an airflow passing over the light metal
components transported through the furnace. The heated airflow then
exchanges heat with the surface of the light metal components due
to the forced convection, thus causing heat transfer from the
airflow to light metal component. The furnace according to the
invention uses hereby the high thermal conductivity of aluminum in
conjunction with the large surface area relative to the mass of the
light metal component, so that the lightweight metal component can
be thermally treated, in particular heated, within a very short
time.
[0025] An exit region is then formed at the exit of the furnace,
wherein the light metal components exiting the furnace prevent the
airflow from escaping from the furnace.
[0026] Both externally heated air as well as hot gas flows may be
used for convection heating. Within the context of the present
invention, the airflow may be any type of gas flow, for example
also the flow of a reaction gas.
[0027] Overall, the furnace according to the invention offers the
advantage that the entire system need not initially be heated at
the startup of production, but only the air circulated in the
furnace must be tempered accordingly. The furnace according to the
invention can thus operate with an effective efficiency and with
significantly lower energy costs compared to a heating system
operating using radiation or induction. In particular, by
circulating the airflow and by preventing the airflow from
escaping, it is possible in conjunction with a thermal
encapsulation of the furnace, to only slightly reheat the heated
airflow with the heat source during circulation, thus significantly
reducing the energy cost during the operation of the furnace
according to the invention.
[0028] According to another advantageous feature of the present
invention, the heat source may be designed as an electric heater
and/or as a fuel-fired heater. The heat source may be arranged
inside the furnace after and/or before the circulation system. The
heated airflow or gas flow advantageously passes directly to the
light metal components, so that no flow losses occur between the
airflow heated directly by the heat source and a long duct system.
After the airflow has passed over the light metal components, it
may enter a duct system and be once more supplied to the
circulating system, wherein it may then be reheated again to the
desired temperature shortly before or after the circulating system
by a heat source disposed therein.
[0029] The choice of heat source, i.e. whether electric heater or
fuel-fired heater, depends in particular on the availability of
energy, the energy costs and the size of the furnace according to
the invention. For smaller lot sizes, it may be beneficial to use
an electric heater. Within the context of the present invention,
however, both types of heating systems may also be combined so that
the furnace is modular and can be used for various purposes.
[0030] According to another advantageous feature of the present
invention, the circulation systems may be arranged as a blower
inside the furnace. Depending on the temperature to be generated,
the blower may be arranged, for example, inside the duct system, or
after the airflow has passed over the light metal components, so
that the airflow or gas flow having an initial temperature reaching
occasionally 600.degree. C. has cooled down on the alloy components
before passing the blowers. The blowers are thus not exposed to the
maximum temperature of more than 400.degree. C. or even of more
than 500.degree. C., but can be operated in a flow of warm air at
about 100.degree. C. to 400 C.
[0031] According to another advantageous feature of the present
invention, the blowers may be used with different air blower
settings, so that the airflow velocity or gas flow velocity, with
which the air flows over the light metal components, is adjustable.
This allows two adjustment parameters in conjunction with a
temperature control, so that heating of the light metal components
can be adjusted via the flow rate and/or the temperature of the air
flow.
[0032] According to another advantageous feature of the present
invention, the furnace may be thermally encapsulated, wherein
sealing elements may advantageously be arranged at the entrance
and/or exit of the furnace; the sealing elements may advantageously
be formed as replaceable baffles. The thermal encapsulation is, for
example, constructed as a thermally insulated jacket of the
furnace, so that residual heat does not escape after passing the
light metal components, or when passing through the duct system of
the furnace.
[0033] Furthermore, particularly in the pulsed or continuous bulk
transport of light metal components into the furnace and out of the
furnace, the entrance and the exit region, i.e. the entrance and
the exit, are therefore critical, since heat, but also the air
flow, may be able to escape due to the convection principle of the
furnace according to the invention. For this purpose, the entrance
and the exit may each be formed such that successive light metal
components which continuously enter and exit the furnace seal the
entrance and/or exit such that a negligible quantity of the airflow
circulating within the furnace escapes. Inevitably, hot air/gas
exiting to the outside through gaps at the entrance and exit can be
collected by way of overlapping hoods and returned to the
circulation, thereby further increasing the efficiency.
[0034] By using the geometry of the components for the purpose of
sealing to enhance the leak-tightness, sealing elements are formed
on the entrance and/or the exit, wherein the sealing elements may
advantageously be formed as a shaped baffle. When using different
light metal components, especially different sized plates, the
shaped baffles may be exchanged so that the cross-sectional area or
the cross-frame area of the light metal components perpendicular to
the transport direction spanning the shaped baffles may be
constructed such that only a small gap is formed in a peripheral
edge region. The furnace according to the invention can thus be
optionally used for light metal components with different geometric
dimensions.
[0035] According to another advantageous feature of the present
invention, the furnace may advantageously have at least two
temperature zones, wherein the light metal components may be used
as a barrier between the zones, and more particularly,
interchangeable shaped baffles may be located at a transition
between the zones. According to another advantageous feature of the
present invention, a first temperature zone and second temperature
zone may thus be formed in a furnace having two different
temperature zones, so that the light metal component crossing from
one zone into another zone operates as a barrier of a transition,
similar as at the entrance or the exit of the furnace. Again,
changeable shaped baffles may be arranged here, so that an
efficient air seal is formed between the zones even when the light
metal components have different geometrical dimensions.
[0036] A mutually different thermal heat treatment may also be
performed in the respective temperature zones by selecting the
airflow speed and/or the air temperature. According to another
advantageous feature of the present invention, two blowers may be
arranged which generate, for example, mutually different flow
velocities in the respective zone. Moreover, two heat sources for
generating different temperatures may also be arranged inside the
furnace. Within the context of the invention, the flow velocity
within a respective zone may also be individually adjusted on the
air nozzles associated with the zones via nozzles having an
adjustable cross-section, so that only one blower is used. In the
context of the invention, a temperature zone may also be configured
as a cooling zone, so that in this case an airflow which is cold
compared with the airflow into heat treatment zone having a
temperature of, for example, 50.degree. C. or even only 10.degree.
C. may flow around the light metal components.
[0037] Advantageously, the shaped baffles may have an opening
corresponding substantially to a transverse frame area of the light
metal components orthogonal to the transport direction. This
ensures that even when a light metal plate is slightly slanted only
small gaps are present when the plate passes through the shaped
baffle, thereby preventing leakage of the air flow.
[0038] According to another advantageous feature of the present
invention, the furnace may have a drying zone in the region of the
entrance and/or a cooling zone in the region of the exit. In this
way, a lubricant or other coating disposed on the light metal
components can first dry in the drying zone or be removed from the
light metal components. The light metal components may thereafter
be thermally treated in the at least one temperature zone and then
optionally cooled down again in a cooling option located at the
exit of the furnace. The components may be cooled down to a
component temperature of 100.degree. C. or even 50.degree. C., or
also to room temperature. In this way, for example, thermal
treatment, solution annealing, aging, or reverse annealing may be
completed in a controlled manner.
[0039] According to another advantageous feature of the present
invention, the circulating airflow inside the furnace may be passed
across a surface of the light metal components, so that the airflow
flows over the entire surface area of the light metal components.
When the air flows over the components, heat is exchanged between
the heated/cold air or hot gas and the comparatively colder or
warmer light metal component. Advantageously, the airflow may pass
continuously across the front side, but also across the rear side
of the light metal component, so that both sides are evenly heated.
The respective temperature set in the light metal component can
then in turn be adjusted by selecting mutually different air
temperatures or mutually different flow rates. For example, the
parameters temperature and flow rate may be adjusted in only one
temperature zone, so that different components can be thermally
treated in the same furnace. When two or more temperature zones are
present, the flow velocity and the temperature may also be adjusted
individually in each zone.
[0040] Advantageously, the light metal components may be
transported through the furnace on a conveyor belt, in particular a
chain conveyor. In the context of the invention, the conveyor belt,
in particular the chain conveyor, includes receptacles or seats
with attachments in which the light metal components, which may be
shaped as plates, can be stored with a substantial vertical
orientation. In addition, the system then becomes more compact, so
that the airflow passes across the components essentially in the
vertical direction from the bottom to the top or from the top to
the bottom. The transport direction then corresponds to a
substantially horizontal direction, so that the vertically oriented
components assume the respective flow guiding and sealing function
between the zones and at the entrance and at the exit. The
components may be arranged at an angle.
[0041] Advantageously, the light metal components themselves may be
heated inside the furnace to a temperature between 200.degree. C.
and 450.degree. C. Metallurgical processes then occur in the
aluminum alloy used in each case, in particular wrought aluminum,
which later produces good formability or a corresponding
homogeneous microstructure with the desired strength
properties.
[0042] The present invention also relates to a method for the
thermal treatment of light metal components in a furnace, wherein
the furnace has at least one of the aforementioned features and the
method includes the following steps: [0043] supplying a conveyor
belt with a plurality of consecutively arranged light metal
components, in particular light metal plates, [0044] transporting
the light metal components through the furnace, wherein the
entrance opening at an entrance of the furnace is sealed by the
respective light metal component passing through the entrance
opening, [0045] producing a continuously circulating warm airflow
and passing the warm airflow across the light metal components in
at least one temperature zone inside the furnace, while the light
metal component is transported through the furnace in either a
clocked or a continuous fashion, [0046] removing the heat-treated
light metal components from the furnace, wherein an exit opening in
an exit region of the furnace is sealed by the respective light
metal component passing through the exit opening.
[0047] With the method according to the invention, consecutively
arranged light metal components, such as also light metal plates,
may be provided on a conveyor belt and continuously moved through a
furnace. A hot air or gas flow may then be generated inside the
furnace using a heat source and circulated with a blower, so that
the hot air or gas flow flows across the light metal components.
The light metal component itself is then heated by the forced
convection on the surface of the light metal component, in
particular on an upper surface as well as a lower surface of the
light metal component, whereby the light metal component, in
particular when using an aluminum alloy, can be heated in a very
short time of sometimes only a few seconds due to its excellent
thermal conductivity.
[0048] According to an advantageous feature of the present
invention, the respective entrance or exit opening may be sealed by
the respective light metal component passing through when the light
metal component enters or exits the furnace, so that the air or gas
flow generated inside the furnace barely escapes to the air
surrounding the furnace. According to another advantageous feature
of the present invention, two or three light metal components
successively passing through the entrance opening may also assume a
sealing function. The same applies to the exit opening.
[0049] Inside the furnace itself, the heating of the light metal
component may be adjusted by selecting the flow rate of the air or
gas flow and/or the air or gas temperature of the air or gas flow.
Two, three or more temperature zones may be separated inside the
furnace, wherein different heating effects can be performed on the
light metal component via the parameters flow rate of the airflow
or temperature of the air flow.
[0050] The heat-treated light metal components may be supplied
within the context of the present invention to further processing,
most advantageously with a cycle time of less than 15 seconds for
each component.
[0051] According to another advantageous feature of the present
invention, the furnace may include a drying zone and a cooling
zone, wherein the light metal components passing the drying zone
are dried in the drying zone; in particular a lubricant present on
the light metal components is dried. Moreover, the light metal
component may be cooled in a cooling zone to a cold-hardening
temperature. Advantageously, a cooling zone may be arranged at the
end of the furnace; however, one or more cooling zones may also be
arranged between the individual temperature zones, allowing a
heated component to be cooled and then reheated.
[0052] According to another advantageous feature of the present
invention, the shaped baffles arranged in the furnace, in
particular at the entrance and in the exit, but also at a
transition between the zones, may be exchanged in a multi-zone
furnace depending on the light metal components to be treated. The
shaped baffles may advantageously be selected such that a
cross-sectional frame area disposed transversely to the transport
direction, in conjunction with the respective light metal component
passing the shaped baffle or also with two or three passing light
metal components, seals in an optimal manner, so that the airflow
cannot escape.
[0053] The above-mentioned features may be combined with one
another within the context of the invention in any manner with the
associated features, without departing from the scope of the
invention. The afore-described parameters can also be applied in
any way to the embodiments described below.
[0054] In another embodiment, in a furnace for the thermal
treatment of light metal components, wherein the light metal
components can be transported continuously through the furnace and
the furnace includes a heat source, an airflow may be circulated
inside the furnace, wherein the light metal components can be
heated inside the furnace by the airflow through convection and
light metal components can be transported on a conveyor through the
furnace, wherein spaced-apart partition walls are arranged on the
conveyor and at least one light metal component may be arranged
between two partition walls.
[0055] The aforementioned features relating, for example, to
different temperature zones, the heat source itself, the flow
velocity or the airflow temperature, but also the sealing elements
in the form of shaped baffles can be combined with this embodiment
without departing from the scope of the invention. A hybrid
structure, wherein the light metal components are themselves
arranged as a barrier in combination with partition walls placed on
the conveyor, may be constructed, whereby the partition walls
representing the larger light metal component are each heated in
the furnace, while smaller light metal components or even complex
shaped light metal components may be arranged between the partition
walls, i.e. between the larger light metal components.
[0056] With this approach, light metal components having different
dimensions may be placed between the two partition walls, wherein
the outer geometry of the light metal components must be smaller
than the outer dimensions of the partition walls, so that the
partition walls assume a sealing function in a continuous transport
process and the light metal components do not protrude over the
partition walls.
[0057] Furthermore, two, three or four or more light metal
components may be simultaneously arranged between two partition
walls and heat-treated at the same time, wherein the light metal
components may also have complex three-dimensional shapes.
[0058] When employing partition walls and placing at least one
light metal component between two respective partition walls, the
furnace may be used for different production runs, without
requiring retrofitting. For example, light metal components having
mutually different outside dimensions, particularly light metal
plates, may be transported in direct succession through the furnace
according to the invention, wherein in the sealing function is
assumed by the partition walls and the plates can be simply
inserted in receptacles arranged between the partition walls. In
this way, the furnace according to the invention can be flexibly
utilized, without requiring set-up times for the conversion of the
furnace for a new production run. This saves acquisition and
maintenance costs of the furnace according to the invention.
[0059] Furthermore, the furnace with partition walls has optionally
at least two mutually different temperature zones, in which the
components are heated to mutually different temperatures. For
example, the component may initially be heated step-wise and/or
cooled step-wise.
[0060] According to another advantageous feature of the present
invention, the partition walls may be constructed to serve as a
barrier, wherein a sealing function is achieved upon passing a
partition wall of an entrance and/or an exit and/or a transition,
so that the airflow is prevented from escaping from the furnace; in
particular, two successive partition walls may form a continuous
seal at the entrance and/or exit and/or the transition. Within the
context of the invention, the transition is located between two
temperature zones, so that the component transitions from one
temperature zone to the other temperature zone.
[0061] Advantageously, a seal may be formed by two consecutive
partition walls which are arranged substantially at an angle
between preferably 10.degree. and 85.degree. with respect to the
transport direction. The partition walls may advantageously be
arranged such that, due to their angular position, the entrance
and/or exit and/or the transition are substantially sealed by two
partition walls, so that a respective airflow is prevented from
escaping from the furnace, or from passing from one temperature
zone into the other temperature zone.
[0062] According to another advantageous feature of the present
invention, the partition walls may be arranged on the conveyor so
that they can be exchanged. Within the context of the present
invention, large partition walls of mutually different sizes may be
arranged on the conveyer itself, or the distance between two
partition walls may be varied. For example, the partition walls may
be arranged on the conveyor with a greater spacing when heating
two, three, four or more light metal components simultaneously,
whereas when heating only a single light-metal component disposed
between the two partition walls, the partition walls may be
arranged with a mutual spacing that leaves only a small gap between
the partition wall, the component and the next partition wall, thus
allowing the airflow to flow across the light-metal component.
[0063] Within the context of the invention, the conveyor may be
designed in particular as a chain conveyor or a conveyor belt. The
conveyor can then be operated continuously, wherein in another
preferred embodiment, the partition walls may be arranged on the
chain conveyor before the entrance and be removed after the exit of
the chain conveyor. In this way, a return of the chain conveyor
requires only a small footprint, which would otherwise be
significantly larger due to the partition walls protruding from the
chain conveyor. Accordingly, a much smaller return cross-sectional
area is required in relation to the cross-sectional area of the
conveyor through the furnace, wherein respective partition walls
are placed on the conveyor.
[0064] Furthermore, the airflow in the furnace may advantageously
be guided by the partition walls themselves and, more particularly,
two mutually different air flows in two mutually different
temperature zones may be separated by a partition wall, wherein the
air flows across the surface of the light metal components. Within
the context of the invention, a respective airflow may thus be
selectively utilized in a separate temperature zone due to the
excellent thermal properties of the aluminum material, so that that
the desired temperature of the light metal component can be
specifically adjusted in the temperature zone by the airflow
flowing across a light metal component.
[0065] Different temperature zones may be separated from one
another by the partition walls, wherein the individual air flows
are guided by the partition walls such that they substantially do
not cross over into a different temperature zone. Within the
context of the invention, the partition walls may advantageously be
insulated, so that heat conduction from one temperature zone into
the second temperature zone by the partition wall itself is
minimized. Furthermore, within the context of the invention, the
partition walls may advantageously be coated, so that the partition
walls dissipate only a small amount of thermal energy from the air
flowing across the partition walls. Advantageously, a thermally
insulating coating may be employed.
[0066] According to another advantageous feature of the present
invention, the partition walls may be arranged at an angle to the
transport direction, for example at an angle between 10.degree. and
80.degree., or between 20.degree. and 70.degree., or at an angle
between 30.degree. and 60.degree. and advantageously at an angle
between 40.degree. and 50.degree.. Arranging two successive
partition walls at an angle at an entrance and/or exit and/or, a
transition advantageously ensures a continuous seal. As a second
advantage, the angular arrangement also separates the air flows of
mutually different temperature zones from each other.
[0067] Another aspect of the invention relates to a method of
operating a furnace, wherein the furnace has a continuous conveyor
for light metal components and at least two partition walls are
arranged on the conveyor, wherein a respective light-metal
component is positioned between the two partition walls and
thereafter passes through the furnace, wherein furthermore mutually
different temperature zones are separated by the partition walls.
Within the context of the present invention, the interior of the
furnace is thus sealed by the partition walls that continuously
travel on the conveyor, wherein the light metal components arranged
between the partition walls are thermally treated by an airflow
circulating within the furnace.
[0068] For this purpose, two consecutively arranged partition walls
seal the entrance region and/or the exit region and/or a transition
region, wherein the airflow circulating in the furnace, in
particular the airflow circulating in the respective temperature
zone of the furnace, is hindered from escaping from the furnace or
from crossing into a different temperature zone.
[0069] According to another aspect of the present invention, the
light metal components can be transported continuously through the
furnace and the furnace includes a heat source, is characterized in
that an airflow can be circulated in the furnace, wherein the light
metal components in the furnace can be heated by the airflow
through convection and the light metal components can be
transported through the furnace on a conveyor, wherein an entrance
and/or an exit of the furnace is sealed by relatively movable
barriers.
[0070] The relatively movable barriers are designed in particular
as fast-opening and fast-closing barriers, wherein a relative
movement of the barriers is preferably a translational movement.
Consequently, a light metal component placed on the conveyor is
transported toward the furnace, with the barrier opening just
before the light metal component enters the furnace, whereafter the
light metal component enters the furnace and the barrier closes
again immediately after the light metal component has entered the
furnace. With this embodiment, light metal components of different
sizes can be transported through the furnace, regardless of their
external dimensions.
[0071] The aforementioned features regarding the heat source, the
blower and the adjustable temperatures and the mutually different
temperature zones also apply to the third embodiment.
[0072] According to another advantageous feature of the present
invention, a relatively movable barrier may be arranged between two
different temperature zones. It is then conceivable within the
context of the invention that three relatively movable barriers may
be arranged at an entrance, in at least one transition between two
different temperature zones and at an exit of the furnace according
to the present invention, which briefly open and immediately close
each time a light metal component passes. The barriers within the
context of the present invention can be simultaneously controlled,
wherein this embodiment is particularly advantageous for light
metal components which are arranged on the conveyor at continuous
intervals. All barriers then open simultaneously, so that in the
embodiment with three barriers, three light metal components then
enter a respective next space of the furnace, whereafter the
barriers close again. This embodiment is advantageous, in
particular, when the circulating airflow is turned off or
decreased. Within the context of the invention, however, each
barrier can also be operated individually, i.e. separately opened
and closed. Separately opening and closing each barrier is
particularly advantageous when light metal components are arranged
discontinuously on the conveyor.
[0073] In the present invention, a relatively movable, in
particular fast-opening barrier is advantageously formed as a
sliding gate, wherein the barrier may be moved up or to one side in
relation to the transport direction of the light metal components,
wherein the barrier is moreover preferable constructed in two
parts, so that each part of the barrier can be displaced to one
side of the furnace. In particular, a long excursion when opening
the barrier is eliminated with a two-part embodiment of the
relatively movable barrier compared to a one-part barrier.
[0074] Even with aperture sizes of 1 m or more, by constructing the
barrier in two parts, each barrier needs to be opened and then
closed again in this case by only 0.5 m. This shortens the opening
and closing times of the barrier especially with the two-part
design.
[0075] Advantageously, an actuator is connected to the barrier for
opening and closing the barrier wherein the actuator preferably
performs a linear movement and can be driven pneumatically,
hydraulically or electrically. An electromechanical actuator is
also contemplated in the present invention. The actuator itself
should be mechanically robust and have a simple design so as to be
unaffected by thermal expansion caused by the thermal loads of the
furnace, and an electronic control unit may optionally be arranged
if possible in the marginal region or outside the furnace itself,
so as to prevent defects due to the thermal loads.
[0076] According to another advantageous feature of the present
invention, the furnace may be surrounded by a shell, wherein the
barriers themselves are positioned in particular inside the shell
or the barriers penetrate the shell and are movable in a slot
extending through the shell for opening and closing. In the first
embodiment, thermal energy is hindered from escaping through the
slots for opening and closing the barrier in particular with
barriers arranged in a transition region from one temperature zone
into a second temperature zone located within the shell. However,
this is only practical for smaller opening widths of the barriers
in order to keep the outer dimensions of the shell also small.
However, when an opening of the barrier of 1 m or more is
necessary, it is advantageous within the context of the present
invention, when the barriers can be moved through a respective slot
of the shell. The barriers then leave at least partially the
interior of the furnace upon opening and return into the furnace
upon closing.
[0077] According to another advantageous feature of the present
invention, heat loss through the slot may be reduced by providing
thermal insulation measures in the slot region. For example, this
may be a thermal seal. In another advantageous embodiment, the
partition walls may themselves be coated and/or thermally
insulated. In this way, the barrier itself can, on one hand, keep
the heat input caused by the airflow flowing across the barrier
small and, on the other hand, prevent the heat from exiting through
the barrier by way of heat conduction at the entrance and/or exit,
as well as prevent--by way of a thermally insulated barrier--heat
transfer by thermal conduction from one temperature zone to the
next temperature zone having a different temperature.
[0078] The invention also relates to a method for operating the
furnace with relatively movable barriers, wherein a light metal
component is placed on the conveyor and the light metal component
is transported into the furnace, wherein the barrier is opened at
the entrance of the furnace just before the light metal component
enters the furnace and is closed again immediately after the
lightweight metal component has entered the furnace and/or wherein
the barrier at the exit of the furnace is opened just before the
light metal component exits from the furnace and is closed again
immediately after the light metal component has exited from the
furnace.
[0079] Airflow recirculated within the furnace may advantageous be
stopped or reduced when a barrier is opened, and may be restarted
or increased after the barrier is closed. This ensures that the
amount of heat escaping the furnace or the heat transfer between
the mutually different temperature zones is reduced to a minimum
when the barrier is opened or closed. The energy costs of operating
the system are thereby reduced.
[0080] Moreover, within the context of the present invention two or
more light metal components may pass the barrier when a barrier is
opened, and when the barrier is closed again after the light metal
components have passed the barrier. In this way, the furnace
according to the invention and the method of operating the furnace
can be flexibly used so that different production lines of metal
components to be heated can be thermally treated with the furnace
without long setup times. For example, light metal components
having different external geometric dimensions, in the form of
plates or even complex-shaped three-dimensional metal components
may be simultaneously thermally treated in the same furnace without
requiring a reconfiguration or modification of the furnace.
[0081] Within the context of the invention, the relatively movable
barriers may advantageously be opened by a control system only as
wide as necessary to create a sufficiently large unobstructed
opening sufficiently for passage of the component according to its
external geometric dimensions. The barrier(s) is/are then closed
again after the component has passed. Thus, for example, an opening
slightly larger than that 1 m.sup.2 may be provided for a large
plate of 1 m.sup.2. For a plate having an area of only 1/4 m.sup.2,
the barrier may be opened only so far as to provide an opening
slightly larger than 1/4 m.sup.2, so that the plate can pass
through the opening, whereafter the barrier is again closed.
[0082] Within the context of the invention, a barrier that opens in
three directions may be selected, wherein the barrier is formed by
two barriers moving toward each side of the conveyor and a barrier
that is movable vertically upward relative to the conveyor, so that
the respective unobstructed areas can be individually adjusted.
This minimizes the energy exiting via the slots when the components
pass into the furnace.
[0083] According to another advantageous feature of the present
invention, the light metal components may be arranged an angle to
the transport direction, in particular at an angle between
30.degree. and 90.degree., allowing many components are to be
transported successively and continuously through the furnace,
wherein the furnace has longitudinal outside dimensions of
maximally several meters, instead of several dozen or even several
hundred meters which would otherwise be required when plates are
placed on the conveyor horizontally, i.e. plates or light metal
components having a lengthwise extension in the transport
direction. The airflow can then be circulated within the furnace
according to the invention from the bottom to the top or from the
top to the bottom and flows across the plates arranged on the
conveyor at an angle to the transport direction and optionally
across the partition walls arranged in between. In summary, a
universally usable furnace having compact overall dimensions for
the heat treatment of light metal components with various
geometrical dimensions can hereby be provided.
BRIEF DESCRIPTION OF THE DRAWING
[0084] Other features and advantages of the present invention will
be more readily apparent upon reading the following description of
currently preferred exemplified embodiments of the invention with
reference to the accompanying drawing, in which:
[0085] FIG. 1 shows the furnace according to the present invention
in a side view;
[0086] FIG. 2 shows a shaped baffle according to the invention in a
plan view;
[0087] FIG. 3 shows an end view of the entrance region of a
furnace;
[0088] FIG. 4 shows an end view with different sized plates;
[0089] FIG. 5 shows a cross-sectional view through the furnace
system with chain conveyor and heat source;
[0090] FIG. 6 shows a furnace according to the invention in a side
view with revolving partition walls;
[0091] FIG. 7 shows a furnace according to the invention with
revolving partition walls;
[0092] FIG. 8 shows a furnace according to the invention with
relatively movable barriers;
[0093] FIG. 9 shows a furnace according to the invention in a plan
view with relatively movable barriers, and
[0094] FIGS. 10a and b shows relatively movable barriers in a
furnace according to the invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0095] Throughout all the figures, same or corresponding elements
may generally be indicated by same reference numerals. These
depicted embodiments are to be understood as illustrative of the
invention and not as limiting in any way. It should also be
understood that the figures are not necessarily to scale and that
the embodiments are sometimes illustrated by graphic symbols,
phantom lines, diagrammatic representations and fragmentary views.
In certain instances, details which are not necessary for an
understanding of the present invention or which render other
details difficult to perceive may have been omitted.
[0096] Turning now to the drawing, and in particular to FIG. 1,
there is shown a furnace 1 according to the invention for thermal
treatment of light metal components 2 in the form of plates. Light
metal components 2 are placed on a conveyor belt 3 and transported
in the transport direction 4 into the furnace 1. For this purpose,
the furnace 1 has an entrance E, through which the light metal
components 2 enter the furnace 1. The same applies for the exit A,
wherein the furnace 1 has an exit A.
[0097] Within the furnace 1, the light metal component 2 first
comes into contact with a drying zone T in which the light metal
component 2 is dried to remove a possible lubricant. An airflow L
circulates within the drying zone T, which flows around both a
front side 5 and a back side 6 of the light metal component 2. The
light metal component 2 transitions from the drying zone T into a
first temperature zone Z1, in which again an airflow L1 flows
around the front side 5 and the back side 6 of the light metal
component 2. The airflow L1 flowing around the light metal
component 2 in the first temperature zone Z1 has hereby a flow
velocity v1 and a temperature T1, thus subjecting the light metal
component 2 to a predetermined component temperature within the
temperature zone Z1.
[0098] Subsequently, the light-metal component 2 enters a second
temperature zone Z2, in which again an airflow L2 flows across a
front side 5 and a back side 6, wherein the airflow L2 of the
second temperature zone Z2 has a second flow velocity v2 and a
second temperature T2. In this way, a component temperature of the
light metal component 2 is adjusted when passing through the second
temperature zone T2.
[0099] After the second temperature zone T2, the light metal
component 2 enters a cooling zone Z3, wherein in the cooling zone
Z3 an airflow L3 again flows across the front side 5 and the rear
side 6 of the light-metal component 2, which has a third flow
velocity v3 and a third temperature T3, wherein in particular the
temperature T3 is lower than the temperature T1 and T2, and the
flow velocity v3 is higher than the flow velocities v1 and v2. The
component is thereby cooled in the illustrated embodiment in the
cooling zone Z3 to a cooling temperature. The component then exits
from the furnace 1 at an exit A and is removed, and then supplied
as heat-treated component 7 to additional unillustrated treatment
processes.
[0100] The individual air flows L can be produced with an
unillustrated blower, and the flow speed v1, v2, v3 can then be
adapted to the respective zone by varying a cross-section or by
using a valve. Within the context of the present invention,
however, each zone may have a separate blower. The same applies to
the temperature. The air may be heated by one or more heat sources,
for example, a separate heat source may be associated with each
temperature zone Z1, Z2.
[0101] In the embodiment shown in FIG. 1, the light metal
components 2 in the form of plates are arranged between insertion
devices 8 so that they are transported through the furnace 1 in the
transport direction 4 with an essentially vertical orientation.
However, within the context of the invention, as shown in FIG. 2,
the plates may also be transported through the furnace
substantially at an angle .alpha.. Shaped baffles 9 are arranged at
both the entrance E and the exit A, as well as between the
individual zones, wherein the shaped baffles 9 are illustrated in
more detail in FIG. 3.
[0102] FIG. 3 shows a shaped baffle 9 according to the invention in
a plan view. The light metal component 2 passes the shaped baffle 9
in the transport direction 4, i.e. towards the image plane, wherein
a gap 12 remains between the outer edge 10 of the light metal
component 2 and the opening 11; this gap 12 needs to be minimized,
so as to minimize the airflow L that can escape through the gap 12
from the temperature zones Z1, Z2, or from the entrance A or exit E
of the furnace 1.
[0103] The light metal component 2 according to FIG. 3 has an
asymmetric configuration; however, large and small rectangular
plates can also be guided through the furnace 1 by exchanging the
shaped baffles 9. This is illustrated in FIG. 4, in which a small
light metal component 2 is captured by the shaped baffle 9 and, as
indicated by the dotted line, a light metal component 2 with larger
geometric dimensions can be transported through the furnace 1 by
exchanging the shaped baffle 9, wherein a small gap 12 remains
between the light metal component 2 and the shaped baffle 9.
[0104] Furthermore, FIG. 5 shows a cross-sectional view through the
furnace 1 according to the invention, wherein the light metal
component 2 is transported through the furnace 1 in the transport
direction 4, wherein the cross-sectional view shows a plan view on
the shaped baffle 9. An cross section through the temperature zone
Z1 is shown as an example. A blower 13 generating the air
circulation within the temperature zone Z1 is located in the lower
part of the furnace 1. The airflow L circulated by the blower 13
passes through a heat register 14 where it is heated and then flows
across the light metal component 2. The airflow L is collected in
an upper region and return to the blower 13. Also illustrated here
are additional heating devices 15, with which the airflow L can be
additionally or exclusively heated, so that the heat source is
located upstream, and not like the heat register 14 downstream of
the blower 13.
[0105] FIG. 6 shows a second embodiment of a furnace 1 according to
the invention, wherein the furnace 1 has once more a conveyor 4 in
the form of a conveyor belt 3, which transports light metal
components 2 in the form of plates 2, 2a, 2b, 2c in the transport
direction 4 through the furnace 1. For this purpose, the light
metal components 2 are placed on the conveyor belt 3 and enter the
furnace 1 through an entrance E in the transport direction 4.
Partition walls 16 are arranged on the conveyor belt 3 at regular
intervals a, wherein two light metal components 2 are each arranged
here between two respective partition walls 16. The furnace 1 shown
in FIG. 6 includes a drying zone T and a first temperature zone Z1
and a second temperature zone Z2, wherein through each of the
drying zone and the temperature zones Z1, Z2 respectively,
corresponding airflow L, L1, L2 flows across the front side 5 and
the back side 6 of the light metal components 2.
[0106] A significant advantage of the present second embodiment
according to FIG. 6 is that even light metal components 2 having
geometries different from the plates 2, 2a, 2b, 2c can be
transported through the furnace 1. For example, plates 2a longer
than the light metal components 2 can be transported through the
furnace 1. Moreover, corrugated or grooved plates 2b as well as
three-dimensionally shaped components 2c can be transported through
the furnace. The partition walls 16 each provide a seal at an
entrance E and exit A, as well as between the temperature zones T,
Z1, Z2.
[0107] FIG. 7 shows a similar embodiment as FIG. 6, wherein only
one light metal component 2, 2b, 2c is located here between the
partition walls 16. Within the context of the invention, the
distances a, a1, a2 between the individual partition walls 16 may
be varied, with a.noteq.a1.noteq.a2. The partition walls 16 shown
in FIG. 6 and FIG. 7 can preferably be placed on the conveyor belt
3 before the entrance E into the furnace 1 and removed from the
conveyor belt 3 after the exit A of the furnace 1. The return 17 of
the conveyor belt 3 then needs to have only a small installation
height h.
[0108] FIG. 8 shows a third embodiment of the furnace 1 according
to the invention, wherein relatively movable barrier 18 are placed
at the entrance E and at the exit A and also at the transitions U
between the individual temperature zones T, Z1, Z2. The barriers 18
can then perform a relative movement R in order to enable the light
metal components 2 positioned on the conveyor belt 3 to be
transported in a transport direction 4. The relatively movable
barriers 18 of the present invention also allow thermal treatment
of components or plates 2, 2a, 2b having different lengths, for
example longer plates 2a as well as corrugated components 2b, in a
the same furnace 1.
[0109] In the embodiment shown in FIG. 8, the plates 2a, 2b are
disposed on respective insertion devices 8 substantially at a
90.degree. angle relative to the transport direction 4 on the
conveyor belt 3. However, the plates 2a, 2b, may also be arranged
at an angle .alpha. on the conveyor belt 3, as shown in FIG. 2, 6
or 7. For this purpose, unillustrated insertion devices 8 or any
other positioning means for insertion on the conveyor belt 3, for
example a chain conveyor, are arranged on the conveyor belt 3 or on
the components or plates themselves. The respective relatively
movable barriers 18 are, as shown in FIG. 8, constructed for upward
or relative movement with respect to the transport direction 4 and
the furnace 1.
[0110] FIG. 9 shows another embodiment of relatively movable
barriers 19a, 19b, wherein the barriers 19a, 19b are here
constructed in two parts and also arranged relatively movable
relative in the furnace 1. The two-part barrier 19a, 19b thereby
performs with one part 19a a relative movement R to one side and
with the second part 19b a relative movement R to the opposite
side. The view shown in FIG. 9 on an inventive furnace 1 from above
thus allows the light metal components 2 to pass in the transport
direction 4 by opening the barriers 19a, 19b. The furnace 1 has
here also two different temperature zones Z1, Z2, wherein an
unillustrated airflow can be circulated in each of the zones Z1, Z2
and the light metal components 2 transported through the furnace 1
can be thermally treated by convection. Furthermore, the furnace 1
shown in FIG. 9 includes a shell 20 surrounding the entire furnace
1, wherein the barriers 19a, 19b are relatively movable inside the
shell 20. The end face of the split barrier 19a, 19b is shown in
the detailed view of FIG. 9, wherein different types of sealing
labyrinths 21 can be formed which prevent the circulated airflow
L1, L2, L3 and/or the heat from crossing over between the two
different temperature zones Z1, Z2, Z3 or prevent heat from
escaping from the entrance E or exit A. For example, the labyrinth
seals may have a U-shaped or C-shaped cross-section.
[0111] FIGS. 10a and 10b show another embodiment of the relatively
movable barriers 18, wherein the barriers 18 perform hereby the
relative movement R by way of a slot 22 disposed in the shell 20.
FIG. 10b shows the barrier 18 coupled with an actuator 23 which
performs the relative movement R as a linear movement, wherein only
a single coupling rod 24 is guided through the slot 22 in the shell
20, thereby preventing possible leakage of airflow L1, L2, L3
and/or heat from the interior of the furnace space.
[0112] While the invention has been illustrated and described in
connection with currently preferred embodiments shown and described
in detail, it is not intended to be limited to the details shown
since various modifications and structural changes may be made
without departing in any way from the spirit and scope of the
present invention. The embodiments were chosen and described in
order to explain the principles of the invention and practical
application to thereby enable a person skilled in the art to best
utilize the invention and various embodiments with various
modifications as are suited to the particular use contemplated.
* * * * *