Note: Descriptions are shown in the official language in which they were submitted.
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Plant for Producing Blocks and Panels with a Honeycomb Structure
from Thermoplastic Plastics
Because of their low weight, great strength and rigidity, and because the
manufacturing
technologies used to produce them are economical, honeycomb materials that are
of
plastic and have an hexagonal cells structure are being used to an increasing
degree in
various areas of technology, for example in machine construction, as
insulating material
in refrigeration technology, in road vehicles and in railway rolling stock,
for example, in
the bodies used for load-carrying vehicles, in scaffolding, in the aerospace
industry, for
high-performance sports equipment, as well as for building racing vehicles and
ocean-
going racing sailboats. Honeycomb materials impart the required safety and
functionality to hi-tech machinery, and aircraft and spacecraft fuselages.
They impart
the desired amount of elasticity to wings and rotor blades, impart the
necessary stiffness
to oceangoing sailboats, and because of their particularly low weight they
make racing
vehicles faster. Honeycomb materials that are of plastic are considerably more
elastic
when under pressure than is the case with honeycomb materials that are of
aluminum.
This is one of the reasons why increasing use is made of such materials for
aircraft
floors.
The present invention relates to a plant for manufacturing block and panel
elements
having an hexagonal honeycomb structure, from thermoplastic plastics, with a
welding
machine for the cyclical welding of strip material so as to form an expandable
skein, a
heater to raise the skein to a working temperature, a device for stretching
the skein, as
well as a cutter for separating blocks or panels that lie one above another
from the skein,
the welder incorporating a holding device for the sections of strip that are
to be welded
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to each other and a heater that incorporates heating elements that can be
moved back and
forth so as to heat the incoming strip sections strip by strip to the welding
temperature of
the strip material; weld strips that are offset by a specific amount are
generated after a
welding cycle by an opposite shift of the heating device in each strip section
that is
conveyed into a magazine. In addition, the welding machine also has a press
device for
welding the strip sections together to form a skein.
DE 198 30 380 A1 describes a plant of this type for manufacturing honeycomb
materials; this plant comprises a section magazine for the strip sections that
are used to
make up the skein, a rotor with a plurality of processing tables, a finishing
table with a
throughfeed magazine, infrared heaters for heating the skein, a pair of
expansion rollers
for stretching the skein, and a cutter for cutting the skein into individual
blocks. The
incrementally driven rotor has six stations spaced at regular intervals around
its
periphery, through each of which a strip section is moved, provided with weld
strips, and
pressed against the skein ahead of the throughfeed magazine. Each of the
rotor's
processing stations has a radially displaceable girder-like beam for a strip
section, a strip
heater that is displaceable ahead of the section carrier, and a roller-like
press device.
The strip heaters are moved axially back and forth, from one processing
station to the
next, so that the strip sections that follow one another in the skein are
provided with
appropriately offset strip welds. During the production of a skein, the strip
heater is
extended during the cyclical rotation of the rotor, so that the strip section
that is taken
from the section magazine lies between the section carrier and the heating
elements of
the comb-like heating device, the section Garner being in a position in which
it is
retracted from the heater. As soon as the processing station is in front of
the throughfeed
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magazine (after three cycles), the strip carrier with the strip section that
is to be welded
on, and the finishing table that can be displaced back and forth, are moved
towards each
other to the point that they contact the comb-like strip heater. Then, the
strip heater is
retracted between the strip section on the strip section carrier and the skein
so that there
is contact between the welding strips on the opposing surfaces of the strip
section and
the skein. Finally, the strip section carrier with the strip section that is
to be welded on
and the throughfeed magazine with the skein are moved further towards each
other until
the strip welds are positioned one above the other. Then, the section carrier
and the
throughfeed magazine are moved apart again, and the rotor is rotated
incrementally.
When this is done, the roller of the press device moves the processing station
that is
being shifted away from the throughfeed magazine over the welded strip
section, so that
the strip section is once again pressed against the skein and the block is
advance by the
thickness of the strip section. These cycles are repeated as soon as the next
processing
station of the rotor is in front of the skein.
The welder that is used in this known plant for manufacturing honeycomb
materials has
the following disadvantages:
The design of the welder with its incrementally driven rotor upon which a
number of
processing stations for the strip sections that are to be welded to the skein
are arranged is
costly from the technical standpoint. When it is operated, there is a risk
that residues of
the material that is used can remain on the pressure rollers of the processing
stations, so
that the operation of the machine is disrupted and it is automatically shut
down. Finally,
the machine has a tendency such that when the pressure roller passes over the
strip
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section that is to be welded on, this will be displaced on the skein and this
will degrade
the quality of the finished honeycomb material.
It is the objective of the present invention to further develop the welding
machine for a
plant of this kind, which is used to manufacture honeycomb materials, in that
it is to be
technically simplified, ensure a greater level of operating safety, and
provide improved
quality of the finished honeycomb materials.
According to the present invention, this objective has been achieved by the
welding
machine described in Patent Claim I, which operates on the principle of
external
welding, and the welding machine described in Patent Claim 2, which is based
on the
principle of internal welding. The secondary claims set out advantageous and
useful
1 S developments of the present invention.
The welders according to the present invention makes it possible to
manufacture
honeycomb materials that are of excellent quality and ensure a high level of
operating
safety.
The present invention will be described in greater detail below on the basis
of the
embodiment shown in the drawings appended hereto. These drawings show the
following:
Figure 1: the layout of a plant for manufacturing block and panel elements
with an
hexagonal honeycomb structure;
Figure 2: a plan view of a welding machine that operates on the principle of
external
welding;
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Figure 3: The area III indicated in Figure 2, at an enlarged scale;
Figure 4a and Figure 4b: plan views of the welding machine with the
alternating
operating positions of the structural elements during two sequential welding
cycles;
Figures Sa to Sd: the sequence of movements of the structural elements of the
welding
machine during a welding cycle;
Figure 6: a plan view of a longitudinal cutting device for cutting the carrier
strips that
are to be processed into individual strips;
Figure 7: a side view of the longitudinal cutting device at an enlarged scale;
Figure 8: a plan view of a welding machine that operates on the principle of
internal
welding;
Figure 9: the area IX indicated in Figure 8 at enlarged scale;
Figure I Oa and 1 Ob: plan views of the welding machine with the alternating
operating
positions of the structural elements during two sequential welding cycles;
Figures 11 a to 11 d: the sequence of movements of the structural elements of
the welding
machine during one welding cycle.
In the following description of the two embodiments of the welding machine for
a plant
for manufacturing honeycomb material, identical or similar components bear
identical
reference numbers.
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The plant for manufacturing block and panel elements with an hexagonal
honeycomb
structure from thermoplastic plastics, as shown in Figure l, comprises a
welding
machine 1 for welding sections of plastic strip to form an expandable a skein
2, a heating
device 3 for heating the skein to the working temperature, a device 4 for
stretching the
skein 2, as well as a cutting device 56 for separating blocks 5 or panels Sa,
Sb, 5 c that
lie one above another from the skein 2.
The welding machine 1 that is shown in Figures 2 to 5, which operates on the
principle
of external welding, is fitted with two strip feed devices 8, 9 that are
arranged on both
face ends 6a and 6b of a magazine 6 that holds strip sections 7. Each of the
strip feed
devices 8, 9 includes a supply roll 10 for a carrier strip 11 that is wound up
to form a
bundle 12, a guide roller 13 that is used to deflect the carrier strip 1 I
that moves in a
vertical plane from the supply roll 10 through 90° into a horizontal
plane, a driven
transport roller 14 with a pressure roller 15 for the carrier strip 11, a
carrier strip store I6
and another guide roller 17 with a pressure roller 18 or, in place of the
guide roller 17, a
longitudinal cutting device 19 for the carrier strip I 1.
The longitudinal cutting device 19 shown in Figure 6 and Figure 7, which is
used to cut
the carrier strip I 1 into three (for example) individual strips 11 a, 11 b,
and 11 c that lie
one above another consists of a receiving roller 22 for two keyway cutters 21
and a
receiving shaft 22 for two top cutter wheels 23that work in conjunction with
the keyway
cutters 21. Use of the longitudinal cutting device I 9 makes it possible to
manufacture a
skein that is divided into layers that lie one above another and which can be
stretched to
form panel-like structural material with a honeycomb structure.
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In order that alternating strip sections 7 can be drawn in, a conveyor 24 of
the welding
machine 1, which is in the form of a gripper 25, can be moved by way of a
strip holder
27 that is attached to a cross rail 26 transversely to the direction of
movement a of a
skein or block skein that is continuously being fabricated on a supporting
table 28 of the
magazine 6, parallel to the strip holder 27 between the two strip feed devices
8, 9.
Cutting devices 29, 30 that are used to separate a strip section 7 from the
carrier strip 11
that is drawn into the welding machine 1, and which can be pivoted in and out,
are
arranged on the two face ends 6a, 6b of the magazine 6.
The strip holder 27 that is secured to the cross rail 26 is in the form of a
longitudinal
beam 31 that incorporates a vacuum chamber 32, the longitudinal beam 31 having
holding bars 33 that incarporates suction bores 34 for the strip sections 7,
which are
connected to the vacuum chambers 32.
In addition to the strip holders 27, a row of heater rails is also arranged on
a cross rail
26; each of these consists of a heating element receptacle 35, including a
cooling
chamber, and a heating element 37 for cyclically welding the strip sections 7-
which are
drawn in alternation from the two strip feed devices 8 and 9-to the last strip
section 7
of the skein 2.
In order to press a strip section 7 that is to be welded to the skein 2 into
place between
the holding bars 33 on the beam 31 of the strip holder 27 there are pneumatic
pressure
cylinders 38 with adjusting pistons 39 for a cross head 40 that is positioned
between
every two holding bars 33, to which the heater rails are articulated
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The welding machine 1 is also equipped with adjusting drives for moving the
cross beam
26 with the strip holder 27, the heating elements 37, and the heating elements
receptacles
3 S after each welding cycle from a front operating position, transversely to
the intake
plane 41-41 of the strip sections 7 in the direction b indicated by the arrow,
into a rear
holding position in order to draw in a new strip section 7 and then move the
cross rail 26
with the strip holder 27, heating elements 37, and the heating element
receptacles 35 in a
direction d, e, which alternates with each welding cycle, by a specific
distance 42,
parallel to the intake plane 41-41 of the strip that is to be welded. The
cross rail 26 with
strip holder 27, heating elements 37, and heating element receptacles 35 is
then moved
in the direction c indicated by the arrow, into the operating position against
the strip
section that is to be welded on to the last strip section 7 of the skein 2,
for strip heating
the strip sections 7 to welding temperature, the strip sections 7 being welded
to each
other by way of the strip welds made by the heating elements 37.
In addition, the welding machine 1 has two comb-like parts 44, 45 that are
arranged so
as to be perpendicular to the plane 43-43 of the supporting table 28 of the
magazine 6 for
the strip sections 7; these can be raised and lowered and moved parallel to
the plane of
the table 43-43 in and against the feed direction 8 of the skein 2. These
parts 44, 45
incorporate catch teeth that provide support for the strip sections 7 that of
the welded to
one another in the area of the strip welds 36, and separate the strip sections
7 between
the strip wells 36, the supporting and separating functions of the two comb-
like parts 44,
45 alternating after each welding cycle.
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Figure 4a and Figure 4b shows the alternating operating positions of the cross
rail 26
with the strip holder 27, the heating elements 37, and the heating element
receptacles 35,
as well as of the comb-like parts 44, 45 during two sequential welding cycles.
In order to generate the hexagonal honeycomb structure, the cross rail 26 with
the heater
bars is moved laterally by a specific distance 42 in opposing directions d, a
from welding
cycle to welding cycle, so that the strip welds 36 or welded seams of two
sequential strip
sections of the continuously developing skein 2 are offset relative to each
other by an
amount that corresponds to the lateral shift 42 of the heater bars, and when
the skein 2 is
stretched this automatically results in the hexagonal honeycomb structure
because of the
offset of the strip welds 36.
During the sequential welding cycles, the comb-like parts 44, 45 with the
catch teeth 46
are shifted in such a way that, for example in the case of the welding cycle
that the
shown in Figure 4a, the part 44 performs the supporting function and the part
45
performs the separating functions for the two strip sections 7 that are to be
welded to
each other and, in the following welding cycle as is shown in Figure 4b, the
parts 44
performs the separating function and the part 45 assumes the supporting
function.
As can be seen in Figure Sa to Figure Sb, during a welding cycle position that
is shown
in Figure Sa, the cross rail 26 together with the heating elements 37 and the
heating
element receptacles 35 that are integrated into these is first moved laterally
and then
forward, in the direction c indicated by the arrow, into the operating
position 26b. When
this occurs, the strip sections 7 that is drawn into the welding machine 1 by
the strip
holder 27 is picked up by its suction bores 34 and moved against the last
strip section 7
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of the skein 2 (Figure Sb). Then, the last strip section 7 of the skein 2 and
the strip
section 7 that is to welded on to this are strip heated by the heating
elements 7 that are
positioned in the heating position 37a by means of a heating current that
pulses through
these so as to bring them to welding temperature, and the two strip sections 7
are welded
together by the strip welds 36 made in these under a constant contact pressure
that is
transferred from the pneumatic pressure cylinders 38 by way of the heating
element
receptacles 35 (Figure Sc). Subsequently, the cross rail 26, together with the
strip holder
27 and the heating elements 37 with the heating element receptacles 35, is
moved back
into the holding position 26a (Figure Sd).
The width 47 of the cells that make up the hexagonal honeycomb structure of
the
finished block or panel material 5; Sa, Sb, Sc is determined by the spacing 48
of the strip
welds 46 of the skein, which is welded together from the individuals strip
sections 27,
and then stretched so as to form the block or panel material.
The welding machine 1 can be modified to manufacture honeycomb materials
having the
desired cell width by incorporating a strip holder 27 with the heating
elements 37 spaced
apart by the distance required for a specific cell, or honeycomb width, as
well as comb-
like parts 44, 45 which alternately function as supporting or separating
elements, which
are spaced apart by a distance 49 between the catch teeth 46 that corresponds
to the
spacing 48 between the heating elements 37.
The welding machines that have been described heretofore are provided with
water
cooling for the heating elements because of the high temperatures that are
involved and
which are caused by using a pulse welding method.
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The welding machine 50, which is shown in Figure 8 to Figure 11, differs from
the
above described external welding machines by the design configuration of the
heating
device for strip heating the strip sections that are welded together to form a
skein, as well
as by the pressure rails that used to weld the strip sections together.
On the cross rail 26 of the internal welding machine 50, apart from the strip
holder 27,
there is a comb-like heating device 51 with tooth-like heating elements 52
that are
arranged in a row and the used for incrementally welding the strip sections 7
that are
drawn into the machine 50 in alternation from the two strip feed devices 8, 9
to the last
strip section 7 of the skein 2, and an adjusting drive for shifting the
heating elements 52
during a welding cycle from below, in the direction f indicated by the arrow,
between the
skein 2 and the strip sections 7 that are to be welded to this and for
withdrawing the
heating elements 52 in the direction g indicated by the arrow, from the gap 53
between
the skein 2 and the strip-like strip sections 7 that have been heated to
welding
temperature and pressed into position.
In order to press each strip section 7 that is to welded to the skein 2 into
position,
between the holding bars 33 on the longitudinal real 31 of the strip holder 27
there are
pneumatic pressure cylinders 38 with adjusting pistons 39 for a crosshead 40
to which
two pressure rails 54 with inserts bars 55 that are of special rubber are
articulated.
As can be seen in Figure 11 a to Figure 11 d, during a welding cycle, after a
strip section
7 has been drawn into the welding machine 50 from one of the two strip feed
devices 8,
9 by means of the gripper 25, the heating device 51 that is in a lower holding
position
51 a is raised, in the direction f indicated by the arrow, into an upper
intermediate
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position Slb so that the heating elements 52 slide between the skein 2 and the
strip
section 7 that is to be welded on (Figure 11 a and Figure I 1 b). Next, the
cross rail 26 that
is in the holding position 26a shown in Figure 11 a, 11 b together with the
heating device
51 and the pressure rail 54 is shifted first laterally and then forward, in
the direction c
indicated by the arrow, into the operating position 26b, 51 c. When this is
done, the strip
section that has been drawn into the welding machine 50 from the strip holder
27 is
picked up by the suction bores 34 and moved against the last strip section 7
of the skein
(Figure 11 c). Then, the last strip of the skein 2 and the strip section that
is to be welded
to it are heated to welding temperature by the heating device 52 that is in
the heating
position by a heating current, and then the heating elements 52 are retracted
by the
heating device 51 being moved downward in the direction g indicated by the
arrow into
the holding position 52b, out of the gap 53 between the skein 2 and the strip
section 7,
and the two strip sections 7 are welded together (Figure 11 d) by the strip
welds 36made
in them under constant contact pressure that is transmitted from the pneumatic
pressure
cylinders 38 by way of the pressure rails 54. Finally, the crosshead 26,
together with the
strip holder 27, the heating elements 52, and the pressure rails 54, is moved
back into the
holding position 26a (Figure 11 a).
The use of a welding machines that operates on the external welding principle
or on the
internal welding principle will depend on the material that is being
processed. For
example, non-woven fabrics can only be processed by using a machine that
operates on
the internal welding principle.
Both types of welding machines make it possible to process expandable
composite
materials that are coated on both sides and are of a thermoplastic plastic.
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