U.S. patent application number 14/246604 was filed with the patent office on 2014-10-09 for method and device for producing a composite sheet-metal part with a metal edge region.
This patent application is currently assigned to ThyssenKrupp Steel Europe AG. The applicant listed for this patent is Azeddine Chergui. Invention is credited to Azeddine Chergui.
Application Number | 20140298875 14/246604 |
Document ID | / |
Family ID | 47002891 |
Filed Date | 2014-10-09 |
United States Patent
Application |
20140298875 |
Kind Code |
A1 |
Chergui; Azeddine |
October 9, 2014 |
Method and Device for Producing a Composite Sheet-Metal Part with a
Metal Edge Region
Abstract
The invention relates to a method for producing a composite
sheet metal part with a metal edge region comprising two outer
covering sheets of metal and at least one layer consisting of a
plastic arranged between the covering sheets. The method is
characterised in that a selected edge region of the composite sheet
metal part is heated in such a way that the plastic layer arranged
between the outer covering sheets softens, by applying a force to
at least one outer covering sheet in the edge region the covering
sheets are pressed against one another at some points or regions,
so that the plastic layer in the edge region subjected to the force
is expelled, and subsequently or at the same time as the
application of the force both covering sheets in the compressed
edge region are joined to one another at least over some regions or
points.
Inventors: |
Chergui; Azeddine;
(Dortmund, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Chergui; Azeddine |
Dortmund |
|
DE |
|
|
Assignee: |
ThyssenKrupp Steel Europe
AG
Duisburg
DE
|
Family ID: |
47002891 |
Appl. No.: |
14/246604 |
Filed: |
April 7, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/EP2012/070041 |
Oct 10, 2012 |
|
|
|
14246604 |
|
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|
Current U.S.
Class: |
72/46 |
Current CPC
Class: |
B23K 11/061 20130101;
B23K 11/34 20130101; B21C 37/02 20130101; B23K 2103/172
20180801 |
Class at
Publication: |
72/46 |
International
Class: |
B21C 37/02 20060101
B21C037/02 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 10, 2011 |
DE |
102011054362.7 |
Claims
1. Method for producing a composite sheet metal part with a metal
edge region, which comprises two outer covering sheets of metal and
at least one layer arranged between the covering sheets consisting
of a plastic, the method comprising the steps of: heating a
selected edge region of the composite sheet metal part in such a
way that the plastic layer arranged between the outer covering
sheets softens, applying a force to at least one outer covering
sheet in the edge region such that the covering sheets are pressed
against one another at some points or regions so that the plastic
layer in the edge region subjected to a force is expelled, and
joining, subsequently or at the same time as the application of the
force, both covering sheets in the compressed edge region to one
another at least over some regions or points.
2. Method according to claim 1, wherein the plastic expelled in the
edge region is at least partially removed mechanically and/or by
means of a suction device.
3. Method according to claim 1, wherein the heating of the edge
region of the composite sheet metal part takes place by at least
one of convectively, conductively, inductively, by friction or by
using electromagnetic radiation.
4. Method according to claim 1, wherein the application of the
force takes place using at least one or more rollers.
5. Method according to claim 1, wherein the edge region is welded
over some points or regions using one or more rollers.
6. Method according to claim 1, wherein the compressed edge region
of the composite sheet metal part sheets for thickness compensation
are arranged at least over some regions on one or both sides.
7. Method according to claim 1, wherein the force exerted during
the heating and expulsion of the plastic layer is greater than
during the joining of the two covering sheets.
8. Method according to claim 1, wherein the composite sheet metal
part is joined at the same time to a further metal part.
9. Method according to claim 8, wherein the composite sheet metal
part comprises only one outer covering sheet of metal and a plastic
layer arranged on the covering sheet, and a second metal covering
sheet is provided by the metal part to which the composite sheet
metal part is to be joined.
10. Device for carrying out a method according to claim 1
comprising: means for positioning a composite sheet metal part,
means for warming an edge region of the composite sheet metal part
over some points or regions of an edge region of the composite
sheet metal part, means for applying a force by means of at least
one covering sheet of the composite sheet metal part in the heated
edge region in order to press this covering sheet against a further
metal sheet so that the heated and soft plastic layer arranged on
the covering sheet is expelled from the edge region, and means for
joining the covering sheet at least over some regions or points to
the metal sheet in the compressed edge region of the composite
sheet metal part.
11. Device according to claim 10, wherein there are provided one or
more rollers for applying a force and/or for heating and/or for
joining the edge region of the composite sheet metal part and also
means for effecting a relative movement between the composite sheet
metal part and rollers.
12. Device according to claim 10, wherein an abrasive device and/or
a suction device is provided to remove the expelled plastic.
13. Device according to claim 10, wherein a first and a second pair
of rollers are provided wherein the first and the second pair of
rollers are arranged behind one another viewed in the longitudinal
direction of the edge region of the composite sheet metal part,
wherein the first pair of rollers is used for heating and
compressing the edge region of the composite sheet metal part and
the second pair of rollers is used for joining, over some points or
regions, the edge region of the composite sheet metal part.
14. Device according to claim 10 wherein a multi-axis arm robot
and/or a handling system is/are provided.
Description
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS
[0001] This patent application is a continuation of
PCT/EP2012/070041, filed Oct. 10, 2012, which claims priority to
German Application No. 102011054362.7, filed Oct. 10, 2011, the
entire teachings and disclosure of which are incorporated herein by
reference thereto.
FIELD OF THE INVENTION
[0002] The invention relates to a method for producing a composite
sheet metal part with a metal edge region, which comprises two
outer covering sheets of metal and at least one layer consisting of
a plastic arranged between the covering sheets. In addition, the
invention relates to a device for carrying out the method according
to the invention.
BACKGROUND OF THE INVENTION
[0003] Composite sheet metal parts are often used in the form of a
sandwich sheet, which comprises two outer covering sheets and a
non-metallic sheet, normally consisting of a plastic that is
arranged between the covering sheets. One reason for the increasing
use of composite sheet metal parts is the fact that composite sheet
metal parts can have properties that are often mutually excluded in
a sheet of solid material. A composite sheet metal part provides
for example, despite its low weight, locally extremely good
stiffness properties and can at the same time exhibit very good
sound-damping properties. Many applications mean, however, that
these composite sheet metal parts have to be joined to other sheet
metal parts or metal parts. The joining methods commonly used with
sheets, such as fusion welding and soldering, cause problems,
however, on account of their high energy input. With the high
energy input, the composite sheet metal part may be damaged due to
the fact that the non-metallic layer or plastic layer arranged
between the covering sheets is damaged by the heat input, and as a
result a sufficiently good connection between a composite sheet
metal part and a metal part can be achieved only with difficulty.
Hitherto various approaches have been attempted in order to solve
this problem. From Japanese patent application JP 06-087079 A it is
known to prepare the edge region, often used for the joining to
further parts, of a composite sheet metal part for a weld joint by
first of all heating the edge region of the composite sheet metal
part, bending the two outer covering sheets over in the edge
region, and removing the plastic layer arranged between the
covering sheets by employing abrasive means. The covering sheets of
the edge region are then welded to one another, so that a composite
sheet metal part with a purely metal edge region is made available,
which can then be used for conventional joining methods. This
method is, however, very complicated and can be automated only with
difficulty.
[0004] Starting from this prior art the object of the present
invention is accordingly to provide a method for producing a
composite sheet metal part with a metal edge region that enables a
corresponding sheet metal part to be produced economically and with
a high degree of automation. In addition, the object of the
invention is to propose a device to be used for carrying out the
said method.
SUMMARY OF THE INVENTION
[0005] According to a first teaching of the present invention the
afore described object is achieved by a generic method, in which
[0006] a selected edge region of the composite sheet metal part is
heated so that the plastic layer arranged between the outer
covering sheets softens, [0007] by applying a force to at least one
outer covering sheet in the edge region the covering sheets are
pressed against one another at some points or regions, so that the
plastic layer in the edge region subjected to a force is expelled,
and [0008] subsequently or at the same time as the application of
the force both covering sheets in the compressed edge region are
joined to one another at least over some regions or points.
[0009] In contrast to the method known from the prior art the
covering sheets are not bent over and the plastic layer is not
removed via abrasive means, but due to the application of a force
to at least one outer covering sheet the plastic layer is expelled
from the edge region. The edge region of a composite sheet metal
part is understood to be a region of the composite sheet metal part
that is a distance of 10 mm to 100 mm from the edge of the
composite sheet metal part. Due to the joining of the two outer
covering sheets over some regions or points in the these edge
regions, in which the plastic has been removed, a composite sheet
metal part is obtained in a simple manner having a purely metal
edge region, which to this extent is therefore also suitable for
the conventionally employed joining methods, such as for example
fusion welding or soldering. Due to the fact that the bending of
the outer covering sheets and the removal of the plastic layer by
using abrasive means can be dispensed with, it is found that the
production of a composite sheet metal part with a purely metal edge
region can be implemented significantly more economically. The
method can also be automated extremely easily and as a result
provides composite sheet metal parts that can be joined very
easily.
[0010] Particularly preferably composite sheet metal parts whose
plastic layer has a greater wall thickness than the associated
metallic covering sheets are joined using the method according to
the invention. For example, the metallic covering sheets can have a
wall thickness of 0.1 mm to 0.3 mm, whereas the plastic sheet has a
wall thickness of 0.35 mm to 0.8 mm. Corresponding composite parts
have considerable weight advantages compared to solid materials,
and can be joined particularly well using the method according to
the invention
[0011] According to a first arrangement of the method according to
the invention the plastic expelled in the edge region is at least
partly removed mechanically and/or via a suction device. A
mechanical removal of the displaced plastic can, for example, be
performed by abrasion using an abrasive device. The combination of
a suction device that sucks out the exiting, soft plastic, and an
abrasive device is also conceivable, so that a finishing operation
of the outer edge region of the composite sheet metal part after
the fabrication of the metal edge region is no longer necessary.
The abrasive device can also at the same time be used for further
tasks, for example electrode cleaning, for example if roller
electrodes are used for heating the edge region or for joining the
edge regions.
[0012] If the heating of the edge region of the composite sheet
metal part is carried out convectively, conductively, inductively,
by friction and/or using electromagnetic radiation, a heated shape
of the edge region of the composite sheet metal part that matches
the intended use can be ensured. With convective warming the heat
transfer takes place for example by hot gases via convection. Use
is made of the fact that the covering sheets can transfer the heat
locally extremely efficiently to the plastic layer arranged between
them. In the case of conductive heating the heating zone can be
limited locally to strictly defined regions, namely the contact
points, through which the current is to flow. In addition, the
means for conductive heating can also be used for the application
of a force. In those cases in which a contact-free, locally
strictly limited heating is desired, this can also take place via
induction, i. e., by inducing eddy currents. A further possibility
of heating the edge region of the composite sheet metal part from
which the plastic layer is to be removed is by friction, for
example in which a sonotrode transmits ultrasound vibrations to the
composite sheet metal part. This heating of the covering sheets of
the composite sheet metal part is also very localised and ensures
that the plastic layer in the remaining regions of the composite
sheet metal part is not adversely affected. At the same time an
ultrasound sonotrode, for example, can be used not only to transmit
a force but also to weld the outer covering sheets in the edge
region. Finally, the use, for example, of electromagnetic
radiation, for example laser radiation in the near infra-red region
or also near infra-red (NIR) radiators, provides a particularly
convenient and effective heating of specific edge regions of the
composite sheet metal part. The use of electromagnetic radiation
enables the heating region to be widened or limited in a
particularly targeted manner.
[0013] According to a further advantageous embodiment of the method
according to the invention the application of the force takes place
using at least one or more rollers. When using rollers, the
contours of edge regions that had previously or simultaneously been
heated can be followed by the rollers, and in this way for example
longitudinal edges of a composite sheet metal part can be provided
in a simple manner with a non-metallic edge region. In this
connection it is not important whether one roller is used, which
exerts a force on an outer covering sheet, the second outer
covering sheet being pressed against a dolly bar or counter holder,
or whether two rollers, respectively arranged opposite one another,
press against the outer covering sheets. In both cases with
conductive heating, for example, the roller can also serve as a
contact roller, which is suitable for conducting the current and
thus allows a punctiform heating of the edge region.
[0014] Preferably, by using one or more rollers the edge region of
the composite sheet metal part is welded over some points or
regions after or during the application of the force. Owing to the
use of the rollers a particularly effective production of a
composite sheet metal part with a purely metal edge region is
ensured. For example, an arrangement of two pairs of rollers viewed
in the longitudinal direction of the edge region can be used to
conductively heat the selected edge region first of all via the
first pair of rollers and to apply a force, and then using the
second pair of rollers to weld the compressed edge region of the
composite sheet metal part over some points or regions.
[0015] In the edge regions of the composite sheet metal part the
overall thickness of the composite sheet metal part is reduced as a
result of the plastic that has been expelled. According to a
further advantageous arrangement of the method according to the
invention, in the compressed edge region of the composite sheet
metal part at least some regions on one or both sides are provided
to compensate the thickness, so that the overall composite sheet
metal part has an almost uniform thickness.
[0016] According to a next advantageous variant of the method
according to the invention, during the heating and expulsion of the
plastic layer between the two outer covering sheets of the
composite sheet metal part, a force is exerted on at least one
outer covering sheet that is greater than that exerted during the
joining of the two covering sheets. In this way the heating
temperatures in the edge region to be prepared can be kept low at
least during the expulsion of the plastic, so that the damage to
the plastic layer that adjoins the metal edge region of the
composite sheet metal part is small. In addition, a particularly
comprehensive expulsion of the plastic between the two outer
covering sheets is thereby achieved, so that the subsequent welding
of the two outer covering sheets is accomplished particularly
easily. The currents employed in a conductive heating and a
subsequent conductive joining can, for example, behave exactly
inversely. In the expulsion of the plastic the currents are lower,
in order simply to soften the plastic layer. With the joining over
at least some regions or points of the outer covering sheets a
higher current can be chosen, so as to enable a joint to be
produced.
[0017] According to a further embodiment of the method according to
the invention the composite sheet metal part is joined at the same
time, i. e. during the fabrication of the metal edge region, to a
further metal part. The fabrication of the metal edge region and
the joining to a further metal part can thereby be accomplished in
a single process step.
[0018] If the composite sheet metal part simply comprises one outer
covering sheet of metal and a plastic layer arranged on the
covering sheet, the second metal covering sheet can be provided by
the metal part to which the composite sheet metal part is to be
joined, so that the composite sheet metal part in the edge region
can be joined without any problem to the metal part by welding. In
this way composite sheet metal parts with an outer covering sheet
and a plastic layer arranged thereon can easily become an integral
component of appliances or devices, for example dishwashers or
railway lines, and their sound-damping properties can be
utilised.
[0019] According to a second teaching of the present invention the
object described above is achieved by a device for carrying out the
method, which comprises [0020] means for positioning a composite
sheet metal part, [0021] means for warming an edge region of the
composite sheet metal part over some points or regions, [0022]
means for applying a force by means of a covering sheet of the
composite sheet metal part in the heated edge region, in order to
press this covering sheet against a further metal sheet, so that
the heated and soft plastic layer arranged on the covering sheet is
expelled from the edge region, and [0023] means for joining the
covering sheet at least over some regions or points to a further
metal sheet in the compressed edge region of the composite sheet
metal part.
[0024] The second outer covering sheet of a composite sheet metal
part with two outer covering sheets and a plastic layer arranged
there between can obviously also be used as a metal sheet. The
device enables the method according to the invention to be carried
out, so that an economic production of the composite sheet metal
parts with two outer covering sheets and a plastic layer arranged
there between, and also comprising a metal edge region, is ensured.
In addition, the device according to the invention also enables a
composite sheet metal outer part with a single outer covering sheet
and a plastic layer arranged thereon to be joined economically to a
further metal part.
[0025] In a simple way longitudinally extending edge regions of a
composite sheet metal part can in one arrangement of the device
according to the invention be produced with a metal edge region,
wherein the arrangement of the device according to the invention is
provided with one or more rollers for applying a force and/or for
heating and/or for joining the edge region of the composite sheet
metal part, as well as with means for effecting a relative movement
between the composite sheet metal part and rollers. The relative
movement between the composite sheet metal part and rollers enables
the contours of an edge region to be followed, and at the same time
the application of force, a heating, and simultaneously a welding
over some points or regions of the two outer covering sheets of a
composite sheet metal part or of the outer covering sheet to a
further metal part, becomes possible.
[0026] A further arrangement of the device according to the
invention enables the edge regions to be machined, for example to
remove excess plastic, is not necessary by providing an abrasive
device and/or a suction device to remove the expelled plastic. On
the one hand, as already explained, a further machining of the
composite sheet metal part is avoided, and on the other hand it can
be ensured via the suction device, which is preferably arranged in
the region of the heating and compression of the edge region, that
excess plastic does not interfere with the joining process of the
two outer covering sheets or of the outer covering sheet to a
further metal part.
[0027] In addition, the device according to the invention can
furthermore be configured so that a first and a second pair of
rollers are provided, wherein the first and the second pair of
rollers are arranged behind one another seen in the longitudinal
direction of the edge region of the composite sheet metal part,
wherein the first pair of rollers is used for the heating and
compression of the edge region of the composite sheet metal part
and the second pair of rollers is used for the joining over some
points or regions of the edge region of the composite sheet metal
part. The processing speeds for the production of the composite
sheet metal parts with a metal edge region can be increased by
allocating the processes of heating and expelling the plastic to
the first pair of rollers, and allocating the joining over some
points or regions of the edge region to the second pair of
rollers.
[0028] Finally, if a multi-axis arm robot and/or a handling system
is provided according to a further arrangement of the device
according to the invention, the automation of the production of
composite sheet metal parts with a metal edge region can be
significantly enhanced. If, for example, the means for the
positioning, the means for the heating over some points or regions
of an edge region of the composite sheet metal part, the means for
the application of a force to the edge region and the means for the
joining of the composite sheet metal part over some points or
regions are controlled via a multi-axis arm robot or a handling
system, a highly automated fabrication of composite sheet metal
parts with a metal edge region can be achieved.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] The invention will be described in more detail hereinafter
with the aid of exemplary embodiments and in conjunction with the
drawings, in which:
[0030] FIGS. 1 and 2 show in a schematic sectional representation a
first embodiment of the method for producing a composite sheet
metal part with a metal edge region, which employs a roller,
[0031] FIG. 3 shows in a schematic sectional view a second
embodiment of the method according to the invention, which employs
two oppositely facing rollers,
[0032] FIGS. 4 and 5 show a third embodiment of the method
according to the invention in a schematic sectional view, in which
an abrasive and suction device is used,
[0033] FIG. 6 shows in a schematic sectional view the
implementation of a fourth embodiment of the method according to
the invention with pairs of rollers arranged behind one
another,
[0034] FIG. 7 shows a force/current/time diagram of one embodiment
of the method according to the invention,
[0035] FIGS. 8 and 9 show in schematic sectional views two further
embodiments of the method according to the invention with different
methods for heating the edge region of the composite sheet metal
part,
[0036] FIGS. 10 and 11 show a device for carrying out an embodiment
of the method according to the invention with conductive heating of
the edge region of the composite sheet metal part,
[0037] FIG. 12 shows in a schematic, partially perspective
representation, the implementation of the method according to the
invention on a flat composite sheet metal part,
[0038] FIGS. 13A-13D show in a schematic sectional view four
embodiments of a composite sheet metal part with a metal edge
region, produced by the method according to the invention,
[0039] FIGS. 14A-14B and 15A-15C show the use of a composite sheet
metal part produced by the method according to the invention in a
dishwasher, and
[0040] FIGS. 16A-16B and 17 show in schematic sectional
representations the use of a composite sheet metal part produced
according to the invention in a railway track.
DETAILED DESCRIPTION OF THE INVENTION
[0041] A first embodiment of the method according to the invention
is first of all illustrated in FIG. 1 in which a composite sheet
metal part 1 consisting of two outer covering sheets 2, 3 and a
plastic layer 4 arranged between the covering sheets 2, 3, is
heated in its edge region 5 in such a way that the plastic layer 4
in this edge region 5 softens. The heating of the edge region 5 can
take place in various ways and means. In the present exemplary
embodiment a current is fed to the composite sheet metal part 1 via
the roller 6 and the current conducting clamp 7 and via the dolly
bar 8, wherein especially in the contact region of the roller 6,
namely in the edge region 5, a powerful heating of the upper and
optionally of the lower covering sheet 2, 3 takes place so that the
plastic layer 4 provided in the edge region 5 appreciably softens.
As a result of the force transmitted to the roller 6 in the
direction of the composite sheet metal part 1 the upper covering
sheet 2 in the edge region 5 is pressed onto the lower covering
sheet. At the same time the plastic 4 in the edge region is
expelled, so that the edge region 5 becomes purely metallic. This
is illustrated in FIG. 2. As can furthermore be seen from FIG. 2, a
device 9 is provided for removing the expelled plastic 4. In the
case where the two covering sheets 2 and 3 are in contact, the
current now flows from the roller 6 via the edge region 5 of the
composite sheet metal part to the dolly bar 8 and can thereby heat
the covering sheets so that these are welded together, for example.
In the compressed edge region both covering sheets are thereby
joined to one another at least over some regions or points.
[0042] In the figures the thickness relationships of the covering
sheets and of the plastic layers are not shown strictly to scale.
The wall thickness of the plastic layer is preferably larger than
that of the covering sheets. For example, the metal covering sheets
can have a wall thickness of 0.1 mm to 0.3 mm, whereas the plastic
layer has a wall thickness of 0.35 mm to 0.8 mm. Composite sheet
metal parts with covering sheets of 0.25 mm wall thickness and a
plastic layer of 0.4 mm wall thickness are particularly preferred.
Corresponding composite parts have significant weight advantages
compared to solid materials and can be joined particularly
efficiently using the method according to the invention.
[0043] A similar exemplary embodiment of the method according to
the invention is illustrated in FIG. 3 and in FIG. 4. Here two
rollers 6a, 6b are used in order to exert a force on the edge
region 5 which is illustrated by the arrows F. The edge region 5
can as already described hereinbefore be conductively heated by
supplying current via the rollers 6a and 6b and the current
conducting clamp 7. It is, however, also possible to heat the edge
region 5 beforehand by other ways and means, so that the plastic
layer becomes soft and can then be expelled from the edge region 5
by application of the force F. In FIG. 4 it can be seen that in
this embodiment of the method according to the invention two
roller-type electrodes 11a and 11b are additionally used in order
to guide the current flow from one outer covering sheet 2 to the
outer covering sheet 3. The roller-type electrodes 11a and 11b are
connected to one another in an electrically conducting manner. By
means of the roller-type electrodes 11a and 11b and also by means
of the roller-type electrodes 6a and 6b it becomes possible for the
contours of the edge region of a composite sheet metal part to be
followed in the longitudinal direction and in this way the method
according to the invention is in each case carried out so that
heating can take place continuously. With the aid of the contact
and sealing rollers 25 a negative pressure in the housing of the
suction device 9 can basically be produced and the abraded plastic
can be completely removed from the roller-type electrodes 6a, 6b.
Furthermore, it is shown in FIG. 4 that, apart from the device 9
for removing the expelled plastic which is illustrated in the form
of a suction device, an abrasive device 10 is also provided which
is arranged in an abrading manner on the front surface of the
composite part. In addition, two contact or sealing rollers 25 are
arranged which are mounted in a freely co-rotating manner on the
housing of the suction device 9, whereby a negative pressure can be
produced in the housing that has a positive effect on the removal
of the plastic.
[0044] An embodiment of the method according to the invention is
now illustrated in FIG. 5 in which the roller-type electrodes 6a,
6b are cleaned to remove exiting plastic, so that these can be used
satisfactorily for the welding over some regions or points of the
edge region 5 of the composite sheet metal part 1. The abrasive
device 10 can furthermore also be used to remove expelled plastic
at the edge of the composite sheet metal part.
[0045] FIG. 6 shows a further embodiment in a schematic sectional
view. The two pairs of rollers 6a, 6b and 12a, 12b are used in
order on the one hand to heat and compress the composite sheet
metal part 1 in the edge region so that the plastic 4 is expelled
from the composite sheet metal part 1 and can be removed by the
suction device 9. The composite sheet metal part 1 then passes
through the pair of rollers 12a and 12b which for the welding over
some points or regions are arranged, viewed behind the first pair
of rollers 6a and 6b, in the processing direction and in the
longitudinal direction of the composite sheet metal part. The
procedure involving the compression and expulsion of the plastic as
well as the welding of the upper and lower covering layers is
thereby divided, so that both procedures can be controlled more
precisely. Furthermore, owing to this arrangement the processing
speed can also be increased. For example, a roller seam can be
produced in a simple way in the edge region of the composite sheet
metal part at a relatively high rate via the roller electrodes
regardless of the expulsion of the plastic in the edge region.
[0046] The force/time diagram and current/time diagram illustrated
in FIG. 7 describes an embodiment of a method according to the
invention with conductive heating and joining of the edge region of
the composite sheet metal parts. The production procedure is
divided into two sections: in the first section the heating and
expulsion of the plastic layer lasting from t0 to t1, and a welding
phase lasting from t1 to t2. In the heating and expulsion phase of
the method according to the invention a relatively small current I
and a relatively high force F are exerted via the rollers on the
edge region of the plastic part. The relatively small current in
relation to the welding phase allows an adjusted heating of the
plastic layer between the two outer covering sheets 2, 3 so that on
account of the great force this plastic layer can be expelled from
the gap between the two outer covering sheets in the edge region 5
until the two covering sheets 2, 3 contact one another at time t1
and there is virtually no longer any plastic between them. The
welding phase lasting from t1 to t2 can then start, in which the
force F can be reduced, though the current I is increased further
so that the metal covering sheets weld to one another.
[0047] FIG. 8 shows a further exemplary embodiment of the method
according to the invention, in which the edge region of the
composite sheet metal part is heated and compressed by friction, in
particular using ultrasound sonotrodes 13a and 13b. In addition,
the suction device 9 is again shown in FIG. 8. A further
possibility of heating the edge region is shown schematically in
FIG. 9. In FIG. 9 means 14a, 14b are provided for the inductive
heating and a pair of rollers 15a, 15b is arranged behind them with
the aid of which the soft plastic is expelled so that the two outer
covering sheets of the composite sheet metal part 1 can then be
welded to one another. Instead of the means for the inductive
heating 14a and 14b there can furthermore obviously be used means
for heating the edge region using electromagnetic radiation for
example laser radiation or near infra-red radiation which also lead
to an effective, contact-free heating of the edge region of the
composite sheet metal part.
[0048] Resistance welding of the edge region of the composite sheet
metal part is preferred, however. FIG. 10 shows the current
conduction paths that are necessary for this purpose. Thus, on the
one hand, a current bridge 16 is provided between the roller-type
electrodes 11a and 11b. In addition, the roller-type electrodes are
connected to one another via a further current bridge 17 in which
the current is conducted via sliding contacts, as illustrated on an
enlarged scale in FIG. 11, through the roller-type electrodes 6a
and 6b to the current bridge 17. The power source 18 is connected
via the roller axes of the roller-type electrodes 6a and 6b. FIG.
12 now shows schematically one view of the production of the
composite sheet metal part with a metal edge region. In the process
step A the starting point is a composite sheet metal part 1
comprising two outer covering sheets 2, 3 and a plastic layer 4
arranged between the covering sheets. The flat composite sheet
metal part or composite sheet thereby produced is passed in the
process step B to a handling system 19. The handling system 19a has
a device 19b according to the invention for producing a composite
sheet metal part with a metal edge region. Alternatively, the
device 19b can also be arranged on a multi-axis arm robot 19. The
multi-axis arm robot 19 or the handling system 19a now follows the
contours of the edge regions 5 of the composite sheet metal part 1
and produces a purely metallic edge region there. The edge regions
have a width of approximately 10 to 100 mm. Alternatively, the
composite sheet metal part 1 can also first of all undergo a
forming process and then be fed in the formed state as process step
B' to the handling system 19a, which then moves round the edge
region 5 of the composite sheet metal part 1a and thus produces a
purely metallic edge region 5. In the process step C the thus
produced composite sheet metal part 1 which is flat or possibly
pre-formed with a metal edge region can be passed to a further
forming step or processing step. The section C' now shows on an
enlarged scale once again the edge region 5 of the composite sheet
metal part 1. The purely metallic edge region 5 comprising no
plastic layer can clearly be recognised. After the forming to
produce the specific composite sheet metal part in the process step
D the said composite sheet metal part can be joined to further
sheet parts as illustrated in the process step E via a seam
formation 20 or by welding to a further structural part as
illustrated in E'. The composite sheet metal part with a metal edge
produced according to the invention can, as illustrated in E and
E', be joined in a simple manner to further structural parts by
using conventional joining techniques.
[0049] FIGS. 13a), b), c) and d) show in a schematic sectional view
the edge regions 5 of composite sheet metal parts 1 that have been
produced with exemplary embodiments of methods according to the
invention. In FIG. 13A both outer covering sheets 2, 3 are pressed
against one another, so that the composite sheet metal part 1
tapers on both sides in the edge region 5. In FIG. 13B on the other
hand only the upper covering sheet 2 has been deformed so that a
thickness compensation, as illustrated in FIG. 13D, is achieved by
unilateral arrangement of a further sheet 2a. FIG. 13c shows the
thickness compensation in the case of an edge region 5 tapering on
both sides of a composite sheet metal part 1. Here both sides are
to be covered with sheets 2a and 3a. Common to all four illustrated
exemplary embodiments is that they comprise a welding 5a in the
edge region, which joins the sheets 2a, 3a provided in the edge
region 5 or covering sheets 2, 3 of the composite sheet metal part
to one another.
[0050] Further application possibilities of the method according to
the invention are illustrated in FIGS. 14A and 14B and also 15A,
15B, and 15C. In FIG. 14A a composite sheet metal part 1'
comprising an outer covering sheet 2' and a plastic layer 4' is
joined to a stainless steel sheet 22 of a dishwasher. In this
connection the edge region of the composite sheet metal part 1'' is
heated by a roller-type electrode 6a, the plastic layer 4' is
expelled and the edge region is then welded to the stainless steel
sheet 22. FIG. 14B shows the finished produced composite sheet
metal part 1' installed on a dishwasher 23. The method is
illustrated in its individual steps once again in FIG. 15A and 15B
as well as 15C. First of all a contact electrode 6a is positioned
in the edge region of the composite sheet metal part 1' as
illustrated in FIG. 15A and the plastic in the edge region 5 is
heated and removed from the gap between the sheets 2' and 22. Then
in a second process step using a resistance welding procedure the
outer covering sheet 2' is welded to the stainless steel sheet 22.
In this case an additional roller-type welding electrode is used so
that the steps 15A and 15B can follow one another in succession.
The finished produced composite sheet metal part 1' is then
fastened to a dishwasher 23. The composite sheet metal parts 1'
lead to a significant sound-damping effect and can be fastened in a
simple manner using the method according to the invention, for
example to a dishwasher.
[0051] Finally, FIGS. 16A, 16B, and 17 show a further use of a
composite sheet metal part 1 with a metal edge region 5 produced
according to the invention. The composite sheet metal part 1'
comprises, as in FIGS. 14 and 15, simply one outer covering sheet
2' and a plastic layer 4'. In the first process step the plastic
layer 4' in the edge region 5 of the composite sheet metal part 1'
is heated via a roller-type electrode 6a and expelled from the gap
between the outer covering sheet 2' and the rail 24, which in this
case forms the metal part. The outer covering sheet is then welded
to the rail 24 using a welding electrode 25 which can also be
formed as a roller-type electrode. FIG. 17 shows a sectional view
of the sound-damped rail 24, which respectively comprises two
composite sheet metal parts 1' on both sides. As is evident from
the applications discussed hereinbefore, a composite sheet metal
part 1' with an outer covering sheet 2' and a plastic layer 4'
arranged thereon can be joined in a simple manner by the method
according to the invention to a further metal part, for example to
the rear wall of a dishwasher 22 or a rail 24. The method according
to the invention in this way significantly broadens the possible
applications of composite sheet metal parts.
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