Note: Descriptions are shown in the official language in which they were submitted.
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Method and Device for Manufacturing a Bonded Part
The invention relates to a method for manufacturing a bonded part
according to the preamble of Claim 1 as well as a device for
using the method as well as the use of a bonded part.
JP-OS 1-275831 A describes the manufacture of an aluminum bonded
part: thin aluminum foam disks are cut from an aluminum foam
block and glued over a large area of an aluminum sheet. The
known manufacturing method for a bonded part according to the
species is very costly: in a first step, an aluminum foam block
is produced, from which flat aluminum disks are cut in a second
step. In a third step, these disks are glued to the aluminum
sheet . Since the surfaces of the aluminum foam disks to be glued
have open pores because of the cutting process, considerable
amounts of adhesive are required and this also contributes to
increased weight of the bonded part. In addition, the method
described is only suitable for making flat bonded parts.
The goal of the invention therefore is to provide a method and
a device for simple, rapid, and economical manufacture of a
bonded part so that the disadvantages of the prior art can be
avoided.
This goal is achieved by the characterizing features of Claim 1.
Claims 8 to 10 relate to devices according to the invention for
using the method.
The basic idea of the invention is to produce the bond between
the metal plate and the metal foam in the manner of diffusion
adhesion in which a hot, not preformed metal foam is applied
directly to the metal plate. In this respect it is suggested to
combine the manufacture of the bonded part directly with the
manufacture of the metal foam. In this manner, a metal foam
block is not manufactured first which must be cut into metal foam
disks after it cools and then glued to the metal plate in a
separate work step, but the foam production and manufacture of
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the bonded part take place in direct sequence. This produces a
simple and economical method with which bonded parts according
to the species can be made without using an adhesive.
The metal foam according to the invention is in a state in which
it can still be molded, preferably in a molten state. Even
doughy metal foam ("semi-solid foam") can be processed.
The term "metal" is defined in conjunction with the invention as
a metal alloy with viscosity-increasing components that serve to
stabilize the molten foam structure.
The "metal plates" of the present invention are not necessarily
flat structures but can be shaped as desired within wide limits
as to their dimensions and shape, as is the case for example in
body parts produced by deep-drawing metal.
The improvement to the invention according to Claim 2 ensures a
safe and load-carrying bond between the metal foam and the metal
plate, in which, by preheating the metal plate, a cooling of the
metal foam that impedes diffusion adhesion is avoided at the
interface with the metal plate.
In addition, the embodiment of the invention according to Claim
3 creates the preconditions required for bonding the two bonded
components. The gelling agent used reduces surface tension and
can also result in etching of the surface of the metal plate.
As a result of the advantageous embodiment of the invention
according to Claim 4, a manufacturing method is made available
that can be used commercially that permits automated mass
production of bonded parts in an economical fashion. The metal
foam is supplied in a continuous process to one edge of the metal
plate, which can be made for example as an endless metal sheet,
so that insertion and removal of individual metal plates is
avoided.
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3
Foam can be manufactured for example by the method described in
U.S. Patent 4,973,358A.
The method described in Claim 5 makes it possible to adjust the
thickness of the metal foam layer individually in a simple
fashion, with the regulating device ensuring a constant thickness
and smooth surface.
Heating the regulating device (Claim 6) facilitates the
manufacture of a flat surface on the metal foam layer. Depending
on the temperature and shape
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of the regulating device it is possible to produce a closed metal
foam surface. Thus the finished bonded part can be cleaned even
on the metal foam side in simple fashion or provided with
additional elements.
To cool the metal foam it is possible for example to provide,
connected downstream from the regulating device, a cooling device
with air outlet openings facing the metal foam.
The improved manufacturing method according to Claim 7 is
particularly economical since the bonded parts do not have to be
removed from the device for embossing and placed in a separate
embossing device. In addition the embossing of the bonded parts,
depending on the material used and the requirements imposed, can
be performed individually at the correct temperature, with
heating or cooling being applied between the regulating and
embossing devices. By using an embossing/cutting tool, combined
embossing and cutting in one work step is possible so that
manufacturing costs and times are reduced and parts tolerances
can be minimized. The desired contour can be embossed on the
bonded part both on the metal plate side and on the metal foam
side.
The method according to Claim 8 uses a cast shape that is simple
to handle and works like a cake mold. The metal plate itself
forms the lower part of the mold and becomes part of the later
bonded part. The upper part of the mold is lowerable into the
lateral enclosing part of the mold. This principle ensures great
freedom as far as shaping the bonded part is concerned; wall
thicknesses and contours can be selected very freely. With the
method described, both simple and complicated
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bonded parts can be manufactured. The wall thickness of the
metal foam can be constant or can vary over the surface of the
metal plate. The metal plate can be flat or preshaped. The
upper part can be made congruent to the metal plate or shaped as
desired. By applying force to the upper part in the direction
of the metal plate, the metal foam can be slightly compressed at
least in its areas near the surface, producing a closed surface.
In addition, by heating the individual cast parts, a closed
surface can be produced on the metal foam layer. In particular,
the metal plate can be preheated to provide a firm bond.
The metal foam required for feeding the casting mold can be
produced for example by the method described in WO 91/01387 A1.
Alternatively, metal foam can be cropped from the melting
crucible as in US 4,973,358 A and placed in the casting mold.
Other manufacturing methods can be also used to make metal foam.
The device according to Claim 9 permits continuous automated
manufacturing processes in which for example sheet metal from a
coil can be coated with metal foam rapidly, economically, and
with constant quality. Eliminating the insertion tasks that
would be required for individual metal plates enables a higher
output.
The deflecting and transport devices can be combined for example
and can be in the form of a powered roller located in the
vicinity of the feed device. It is also possible to use a
deflecting roller in the vicinity of the feed device and to use
a conveyor belt with a large surface that also serves to guide
the metal sheet.
Although a device is known from US 4, 973,358 A that uses a
conveyor belt, this device however merely serves to produce the
metal foam: the metal foam that is placed on the heat-resistant
conveyor belt hardens to form an irregular surface with
increasing distance from the melting crucible and is removed in
a solid state from the conveyor belt for further processing. In
...
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contrast, the present invention comprises a device for making a
complete bonded part with the principle of preparation of the
metal foam according to the U.S. patent being completely usable.
In general, however, other methods can be used to produce the
metal foam.
According to the improvement on the invention in Claim 10 a
device is available in which, by arranging the two stations in
a line (coating, embossing) continuous manufacture of bonded
parts is possible in a continuous production process. By
eliminating the insertion and removal steps between the stations,
manufacturing time is shortened and high output and low
manufacturing costs can be achieved as well. Manufacturing can
largely be automated.
The embossing and cutting device must move in its lowered
position along with the conveyor device for the bonded part for
example by locking when placed upon lateral guides for the
conveyor device.
Claim 11 describes an especially advantageous use of a bonded
part: by combining the two components, the metal sheet is
available as a paintable outer body hull. The metal foam can
fulfill various tasks on the inside, for example for increase the
rigidity of the outer hull or for sound insulation. Thus for
example by using metal foam a stiffening inner body panel can be
eliminated which in many cases is expensive to manufacture and
is characterized by relatively high weight . At the same time the
stiffening metal foam can perform a sound insulating function.
Possible applications include for example bonded parts according
to the invention such as engine hoods, trunk lids, sliding roof
covers, etc. In the case of the engine hood it is also
advantageous if the metal foam is not flammable.
In addition to parts of the outer hull, bonded parts according
to the invention can also be used in the vehicle interior, for
example as a partition between the engine and the interior. In
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this case the metal foam is intended primarily to absorb sound.
Bonded parts in the area of the front and the rear of the vehicle
with correspondingly thick metal foam layers are especially
suitable for absorbing impact by plastic deformation of the metal
foam.
Coverings or components can be fastened especially simply to the
metal foam layer, for example with sheet metal screws. In
addition, molly-type mounting elements whose projections
correspond to the numerous sharp-edged thin partitions of the
bubblelike cavities in the metal foam are especially suitable.
One possible embodiment of the invention will now be described
in greater detail with reference to the drawing. The single
figure shows a device for making a bonded part, in a side view
and in a highly schematic representation.
A melting crucible 1 contains an aluminum alloy 2 in a molten
state. When a gas is supplied,
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a surface layer 3 of aluminum foam 4 filled with gas bubbles
forms on the surface of aluminum melt 2. By means of a conveyor
5, aluminum foam 4 is fed to a transport roller 6 that functions
as a deflecting and transport device. Transport roller 6
reverses an aluminum sheet 7 and feeds it to a horizontal sheet
guide 8. Aluminum foam 4 is brought to the top 9 of aluminum
sheet 7 by conveyor 5. A regulating device 10 located above
transport roller 6, with a doctor blade 11 facing conveyor 5,
adjusts the thickness of aluminum foam layer 12. Regulating
device 10 has openings 13a and 13b to supply cold or hot air.
An embossing and cutting device 14 abuts regulating device 10.
It consists of an embossing mold 15 located below aluminum sheet
7, an embossing punch 16 located above aluminum foam layer 12,
and a cutting tool 17.
Both the transport of aluminum sheet 7 and the transport of
aluminum foam 4 are continuous. Aluminum sheet 7 is heated by
devices not shown, both ahead of transport roller 6 and in sheet
guide 8. At the end of conveyor 5, aluminum foam 4 is brought
to aluminum sheet 7 moving away beneath conveyor 5. Regulating
device 10 limits the height of aluminum foam layer 12. It is
likewise heatable so that top 18 of aluminum foam layer 12 is as
smooth as possible. Through openings 13a of regulating device
10, either hot air for further support of surface smoothing or
cold air to accelerate the setting of aluminum foam layer 12 can
be introduced. The supply of gelling agent
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through openings 13b facilitates the formation of a smooth
surface 18.
By the shape of embossing mold 15 and embossing punch 16 the
contour of bonded part 19 is determined. Cutting tool 17
separates finished bonded parts 19 from continuous aluminum sheet
7.
