Note: Descriptions are shown in the official language in which they were submitted.
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Pallet container
The invention relates to a pallet container having a
thin-walled rigid inner container made of thermoplastic
material for the storage and transportation of liquid
or free-flowing contents, having a lattice frame,
which, as supporting casing, closely encloses the inner
container, and having a base pallet, on which the inner
container rests and to which the lattice frame is
fixed, wherein the lattice frame comprises vertical and
horizontal profile bars which are fixed to one another
at the crossover points.
Prior art
Pallet containers are used for the transportation and
storage of liquid or free-flowing, in some cases
hazardous, contents. During the transportation of
filled pallet containers - in particular in the case of
contents with a high relative density and of the pallet
containers being stacked - on poor roads - using trucks
with stiff suspension, or during transportation by rail
or sea, the lattice frames are subjected to
considerable loading. This transportation-induced
loading, on account of the stack load in the case of
pallet containers being stacked, subjects the lattice
frame to compressive loading in the axial direction
and, as a result of sustained dynamic surge movements
emanating from the liquid contents, additionally
subject the usually welded lattice frame to reversed
bending loading in the radial direction. The weld
connections or the weld regions of the crossover points
of the vertical and horizontal lattice bars or lattice
tubes are the points subject to the highest stressing.
Such stressing, following a certain period of time, can
result in the weld connections or the lattice tubes
rupturing, and this therefore means the necessary level
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of reliability for stacking and transporting such
pallet containers is no longer assured.
All the known pallet containers with tubular lattice
frames have weld connections at the crossover points of
the tubular bars; in the case of some pallet
containers, for the purpose of releasing the weld
regions of loading, bending points which are elastic to
a limited extend are formed in the tubular bars
alongside the weld spots.
Pallet containers with a welded tubular lattice frame
are known in general, for example from
EP 0 734 967 A (Sch). The tubular lattice frame of the
pallet container known from this document comprises a
round-tube profile which, at the welded crossover
points, is indented to a pronounced extent in the form
a hollow and therefore, with the tubes crossed over,
forms four points of contact for the mutual welding.
The bending points which are elastic to a limited
extent are produced by way of additional depressions of
the weld-hollow end regions.
EP 0 755 863 Al (Fust) discloses another pallet
container, of which the lattice bars have a square-tube
profile which is pushed in partially to a slight
extent, merely in the crossover region, for better
welding and thus forms the four points of contact for
the welding. The tube profile otherwise, over its
entire length between the crossover points, has a
constant cross section without any concavities.
DE 196 42 242 Al (Rot) discloses a further pallet
container, having a lattice frame made of open
trapezoidal profile bars and a profile which is
constant over the length of each bar. The four weld
spots at the crossover points are achieved here by the
outwardly flattened planar surfaces of the profile
bars.
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Another pallet container having a continuous tube
profile throughout is known from US 6,244,453 Bl (Mam).
The four weld spots at the crossover points of the bars
are achieved here by the continuous two-sided or four-
sided square-profile depressions with longitudinal ribs
on the outside.
EP 1 289 852 (Mau) discloses a further pallet
container, of which the lattice bars have a trapezoidal
tube profile and four weld spots in the crossover
region. Concavities, which act as predetermined bending
points, are made, in the region alongside the crossover
points of the tubular bars, on that side of the tubes
which is located opposite the weld region.
Another pallet container having four weld spots in the
crossover region of the tubular bars is known from
EP 1 618 047 B1 (Mau). The elasticity behavior of the
tubular lattice frame is achieved here by a reduction
in the cross-sectional height of the tubes between or
outside the welded crossover points.
DE A 10 2010 033 738 1 (R. Bu) describes a special
pallet container, of which the metal cage is
characterized in that the Fixation of the profile bars
of the metal cage is effected by punch riveting, TOX
clinching or straightforward clinching, in the form of
a force-fitting and form-fitting joining connection.
Another pallet container with spot-weld connections and
clinched connections between the ends of the vertical
profile bars of the lattice-profile supporting casing
and the upper horizontal profile bar is also known from
DE A 10 2005 031 940 (Sch).
Finally, a pallet container is known from EP 0 916 592
A 1 (vL), whose vertical and horizontal tubular bars
have differing diameters and are connected in such a
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way that the tubular bars with the larger diameter are
hole punched and the tubular bars with the smaller
diameter are passed through the holes in the tubular
bars with the larger diameter, wherein the tubular bars
may additionally welded at the crossover points.
Disadvantages of the prior art
The hitherto known tubular lattice frames having a
uniform lattice-tube profile throughout and two or four
weld spots at the crossover points all have the
disadvantage that the horizontal and vertical tubular
lattice bars become flexurally and torsionally too
rigid overall in the face of reversed bending stress
occurring during transportation of the filled pallet
containers . Even after a comparatively short period of
stressing, this results in fatigue cracks and rupturing
of the bars, in particular in the vicinity of the
welded crossover points of the lattice bars, or the
weld spots of the crossover points rupture and break
off.
In the case of double stacking of pallet containers, in
particular the attachment between the upper horizontal
profile bar and the vertical profile bars is a weak
point.
Those tubular lattice frames having welded round tubes
with four weld spots, e.g. known from
EP 0 734 967 A2 (Sch), and having a considerably
reduced cross-sectional height of the tubes in the
region of the crossover points (no continuous tube
profile, indentations of the same depth overall and/or
a reduced cross-sectional height of the tubes at the
crossover points of the bars) have the disadvantage
that considerable loading peaks occur in these regions
of reduced tube cross section and, as a result,
predetermined breaking or buckling points are, as it
were, pre-programmed e.g. in the case of drop tests, in
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the case of hydraulic internal pressure tests and in
the case of reversed bending stress due to
transportation-induced loading.
5 Those known tubular lattice frames having four weld
spots in the crossover region of the tubular bars and
adjacent problematic predetermined bending points or
predetermined bending regions - known from EP 1 289 852
and EP 1 618 047 - have the disadvantage that the
tubular-bar regions are not subjected to uniform
loading and it is only the regions of reduced tubular-
bar cross section which have to absorb the reversed
bending stress due to transportation-induced loading.
It is necessary, in principle, for all the tubular bars
of the tubular lattice frames with predetermined
bending points in the starting profile to be over-
dimensioned, because it is only the reduced tubular-bar
cross-sectional height of the predetermined bending
points which absorbs the reversed bending stress, but
this reduces the static loading capability of the
tubular lattice frame as a whole.
Ail the known pallet containers having welded tubular
lattice frames or having welded wire lattices as a
supporting casing have the following disadvantages:
The welding method used is resistance welding, a
straightforward welding method with a high level of
energy consumption; not all materials can be welded by
resistance welding and, during long periods of
transportation, the bending surge loading which occurs
can result in the weld seams rupturing.
Those tubular lattice frames having spot-weld
connections and a further clinch connection between the
ends of the vertical profile bars of the lattice-
profile supporting casing and the uppermost horizontal
profile bar - known for example from DE 10 2005 031 940
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- quite apart from involving disadvantageous spot-
welding, do not have any additional mechanical form-
fitting connections at the other crossover points of
the vertical and horizontal profile bars of the tubular
lattice frame.
Those known tubular lattice frames made of cage-forming
bar profiles which form so-called joining connections
by punch riveting, TOX clinching or straightforward
clinching have the following disadvantages:
If the profiles used for the tubular lattice frame are
conventional ones with a bar width of 15 to 25 mm, the
size or dimensions of the joining connection means that
it possible to realize only one joining connection, or
a maximum of two joining connections, at each crossover
point of the tubular lattice frame, and these joining
connections have to absorb the same forces as in the
case of a pallet container having a tubular lattice
frame with a continuous lattice-tube profile and four
weld spots at the crossover points. If use is made of a
lattice-tube profile made of a non-metallic material,
then the mechanical load-bearing capability of the
joining connection is reduced further on account of the
poor physical characteristics of the non-metallic
material.
Where fixation of the profile bars of the metal cage is
effected solely by punch riveting, TOX clinching or
straightforward clinching in the form of a force-
fitting and form-fitting joining connection, as in
DE A 10 2010 033 738 1 (R. Bu), it is disadvantageous
that the joining connections alone have to absorb all
reversed bending stress and shearing forces (stack
load). Such stressing, following a certain period of
time, can easily result in excessive load.
If the lattice cage is composed of tubular bars and if
the connection of the tubular bars is effected in such
a way that one of the tubular bars is hole punched and
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the other one is passed through the hole
(EP 0 916 592 A 1, vL), flexurally rigid tubes with a
large diameter are weakened severely in a
disadvantageous manner by introducing drill holes or
rather by removing material from the tube wall.
Furthermore, assembly by inserting the different
tubular bars into one another causes unduly high
production costs.
Object
It is an object of the present invention to specify a
pallet container of the type in question which has a
lattice-profile supporting casing made of fixed profile
bars and no longer has the disadvantages of the prior
art - account being taken of the stack load caused by a
filled pallet container stacked on top (double
stacking) in addition to the conventional surge loading
caused by the liquid content during transportation.
The present invention provides a pallet container
having a thin-walled inner container made of
thermoplastic material for the storage and
transportation of liquid or free-flowing contents,
having a lattice-profile supporting casing, which, as
supporting casing, closely encloses the inner
container, and having a base pallet, on which the inner
container rests and to which the lattice-profile
supporting casing is fixed, wherein the lattice-profile
supporting casing comprises crossing-over vertical and
horizontal profile bars, wherein the vertical and the
horizontal profile bars are connected at their
crossover points by mechanical joining operations such
as clinching or punch riveting,
characterized in that
the profile bars at their points of connection,
additionally have a mechanical form fit or a form-fit-
forming bearing region and are fixed in a rotationally
secure manner as a result.
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The profile bars of the lattice-profile supporting
casing can be provided with the additional mechanical
form fit at their crossover points by virtue of the
vertical profile bars being placed in accommodating
grooves of the horizontal profile bars.
The profile bars of the lattice-profile supporting
casing can be provided with the additional mechanical
form fit at their crossover points by virtue of the
vertical profile bars being placed in punched-out
centering means of the horizontal profile bars.
The upper horizontal profile bar of the lattice-profile
supporting casing can bear on the vertical profile bars
at the lattice-profile crossover joint at the top via
the shoulders or the punched-out lower centering means
of the vertical profile bars.
The upper horizontal profile bar of the lattice-profile
supporting casing can bear on the vertical profile bars
at the lattice-profile crossover joint at the top via a
shoulder of the horizontal profile bar.
The vertical profile bars of the lattice-profile
supporting casing can bear on the bearing limb of the
lower horizontal profile bar at the lattice-profile
crossover joint at the bottom.
The vertical profile bars of the lattice-profile
supporting casing can bear on the lower horizontal
profile bar at the lattice-profile crossover joint at
the bottom by way of their punched-out shoulders.
The profile bars of the lattice-profile supporting
casing can consist of different materials and/or can
comprise different cross-sectional profiles.
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The mechanical joining connections can be produced
without any separate preliminary perforations.
The vertical and/or horizontal profile bars of the
lattice-profile supporting casing can have a largely
continuous profile.
The lattice-profile supporting casing can have a rigid
configuration.
The lattice-profile supporting casing can have a
collapsible or foldable configuration.
The vertical and horizontal profile bars can be
connected by mechanical joining only at some lattice-
profile crossover points.
According to an aspect of the present invention, there
is provided a pallet container comprising:
a thin-walled inner container made of thermoplastic
material for storage and transportation of liquid or
free-flowing contents;
a lattice-profile supporting casing, which, as
supporting casing, closely encloses the inner
container; and
a base pallet, on which the inner container rests and
to which the lattice-profile supporting casing is
fixed,
wherein the lattice-profile supporting casing comprises
crossing-over vertical and horizontal profile bars,
which are connected at their crossover-joint locations
by mechanical joining without any preliminary
perforation of the profile bars,
wherein the crossing-over vertical and horizontal
profile bars are fixed to one another in a form-fitting
manner at their crossover points by means of a
mechanical form fit and thus are fixed in a
rotationally secure manner by mechanical locking,
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9a
wherein the vertical profile bars on a side of the
vertical bars which is directed towards the horizontal
profile bars each have, at their crossover points, a
bearing region which is deformed for the mechanical
form fit and the vertical profile bars, in respect of
their respective positioning in the lattice-profile
supporting casing, on their side which is directed
towards the horizontal profile bars, or the horizontal
profile bars on a side of the horizontal bars which is
directed towards the vertical profile bars, each have a
respective bearing region which is deformed for
relieving joint connections of loading in the region of
the crossover-joint locations and, in addition, the
profile bars are connected in their crossover points by
the mechanical joining without any preliminary
perforation of the profile bars.
The pallet container for liquids according to the
invention having a lattice-profile supporting casing,
which, as supporting casing, closely encloses the inner
container, and having a base pallet, on which the inner
container rests and to which the lattice-profile
supporting casing is fixed, wherein the lattice-profile
supporting casing, which may be rigid or collapsible,
comprises vertical and horizontal profile bars which
are fixed to one another at the crossover points, is
distinguished by the following advantages:
There is no welding at all the connecting locations of
the lattice-profile supporting casing, connection takes
place by mechanical joining, it is also possible to
connect profiles consisting of materials which cannot
be subjected to resistance welding, it is possible for
example for profile bars made of steel, aluminum,
composite materials and plastic to be connected to one
another, the connecting zone is not influenced
thermally in any way and mechanical joining, by having
a lower level of energy consumption, is more cost-
effective. The profile bars may have different wall
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thicknesses and be configured in the form of a bar
profile, shaped profile or hollow profile. The
mechanical joining connections can also be produced
without any preliminary perforations, with
accessibility on one side. Mechanical joining
connections have high dynamic load-
bearing
capabilities.
In addition, the profile bars are locked in relation to
one another at their crossover points by a mechanical
form fit, and are supported mechanically at the
lattice-profile crossover joints of the upper and lower
horizontal profile bar, in order to relieve the clinch
or punch riveting joining connections of loading. In
the case of a mechanical joining connection per
lattice-profile crossover joint, in particular in the
case of foldable or collapsible lattice-profile
supporting casings comprising separate side parts, this
mechanical form fit also reinforces the design strength
thereof.
In the case of double stacking of the pallet
containers, the stack load caused by the pallet
container stacked on top has to be absorbed by the
upper horizontal profile bar of the lattice-profile
supporting casing and transferred to the base pallet
via the vertical profile bars and the lower horizontal
profile bar. The punch rivet, clinch rivet or clinch-
joining connections are effectively relieved of the
stack loading here by additional bearing surfaces on
the upper and lower lattice-profile crossover joints.
In one embodiment of the invention, the lattice-profile
supporting casing of a pallet container may be of
collapsible or foldable configuration. With the same
surface area at the base, the pallet-container height
here is reduced to approximately 1/3 of the original
height. The advantage with this configuration is that
the reduced volume of the collapsed pallet container
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makes it possible for the transportation costs and the
costs for storing the pallet container without an inner
container inserted therein to be reduced to a
considerable extent.
The invention will be described and explained in more
detail hereinbelow with reference to exemplary
embodiments which are illustrated schematically in the
drawings, in which:
figure 1 shows a front view of a pallet container
according to the invention,
figure 2 shows a side view of a pallet container
according to the invention,
figure 3 shows a view of a double-stacked pallet
container according to the invention,
figure 4 shows a view of a lattice-profile crossover
point according to the invention (18 in
figure 2),
figure 5 shows a section A-B through a vertical
profile bar from figure 4,
figure 6 shows a section C-D through a lattice-profile
crossover point in figure 4 with a mechanical
joining connection produced by clinching,
figure 7 shows a section C-D through a further
lattice-profile crossover point from figure 4
with a mechanical joining connection produced
by punch riveting using a semi-tubular rivet,
figure 8 shows a section C-D through a further
lattice-profile crossover point from figure 4
with a mechanical joining connection produced
by punch riveting using a solid rivet,
figure 9 shows a section E-F through a horizontal
profile-bar bearing means from figure 4,
figure 10 shows a section E-F through a horizontal
profile-bar mount from figure 4,
figure 11 shows a section E-F through a further
horizontal profile-bar mount from figure 4,
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figure 12 shows a view of an upper lattice-profile
crossover joint (24 in figure 2),
figure 13 shows a standard profile-bar connection,
upper horizontal/vertical profile bar, in
accordance with section G-H in figure 12,
figure 14 shows a profile-bar connection according to
the invention, upper horizontal/vertical
profile bar, in accordance with section G-H
from figure 12,
figure 15 shows a further profile-bar connection
according to the invention, upper
horizontal/vertical profile bar, in
accordance with section G-H from figure 12,
figure 16 shows a further profile-bar
connection
according to the invention, upper
horizontal/vertical profile bar, in
accordance with section G-H from figure 12,
figure 17 shows a view of lattice-profile crossover
joint according to the invention at the
bottom (26 in figure 2),
figure 18 shows a standard profile-bar connection,
lower horizontal/vertical profile bar, in
accordance with section I-J from figure 17,
figure 19 shows a profile-bar connection according to
the invention, lower horizontal/vertical
profile bar in accordance with section I-J
from figure 17,
figure 20 shows a further profile-bar
connection
according to the invention, lower
horizontal/vertical profile bar, in
accordance with section I-J in figure 17, and
figure 21 shows a further profile-bar
connection
according to the invention, lower
horizontal/vertical profile bar, in
accordance with section I-J from figure 17.
Figure 1 illustrates a front view of a pallet container
10 according to the invention having a thin-walled
rigid inner container 12 made of thermoplastic
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material, having a lattice-profile supporting casing 14
and having a base pallet 16 (pallet width 1000 mm).
Figure 2 shows a side view of the pallet container 10
(pallet length 1200 mm).
Figure 3 shows a double-stacked pallet container 10
according to the invention. This type of stacking is
conventional during transportation for example by truck
or in sea-going freight containers in accordance with
ISO 668. In the case of double stacking, the lattice-
profile supporting casing 14 of the pallet container 10
stacked underneath is subjected to loading during
transportation not just by the surge forces caused by
its contents (radial loading), but also by the weight
of the pallet container 10 stacked on top (axial
loading).
Figure 4 shows a lattice-profile crossover point 18 of
the lattice-profile supporting casing 14 according to
the invention formed by two U-shaped bar profiles 28
according to Figure 5. Sections C-D from figures 4, 12
and 17 show the horizontal 22 and vertical 20 profile
bars with their mechanically joined connection. The
sections C-D in figures 4, 12 and 17 are the same; the
mechanical joining connections can be made in
accordance with figures 6, 7 and 8.
Figure 6 shows a mechanical joining connection between
the U-shaped vertical 20 and horizontal 22 profile bars
produced by means of clinching. The mechanical clinch
connection is achieved by material being pushed in and
displaced from the clinch cavity region 30 of the
horizontal profile bar 22 and by subsequent insertion
and pressing operations in the clinch-joining region 32
of the vertical profile bar 20. It is advantageous with
this mechanical joining connection that there is only a
low level of energy consumption and the joining zone is
not influenced thermally in any way.
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Figure 7 shows a further mechanical joining connection
according to the invention between the U-shaped
vertical 20 and horizontal 22 profile bars. The
mechanical joining connection is made by the semi-
tubular rivet 34, which forms the semi-tubular-rivet
joining region 36 by punch riveting and thus
permanently connects the vertical 20 and horizontal 22
profile bars.
A further mechanical joining connection according to
the invention is the punch riveting method using a
solid rivet 38, that has been illustrated in figure 8.
The mechanical joining connection between the profile
bars 20 and 22 is produced by the solid punch rivet 38
and by the displacement of material into the joining
region 40 of the solid punch rivet 38. Punch riveting
using a solid rivet 38 takes place, as with punch
riveting using the semi-tubular rivet 34, without
preliminary drilling and is therefore straightforward
to automate.
Figures 9, 10 and 11 show the horizontal profile bar 22
bearing on the vertical profile bar 20 at a lattice-
profile crossover point 18 of the lattice-profile
supporting casing 14 according to the invention,
wherein the horizontal profile bar 22 is additionally
fixed in a form-fitting manner in the vertical profile
bar 20 via the accommodating groove 42 in figure 10 or
via the punched-out centering means 43 in figure 11.
The view of a lattice-profile crossover joint according
to the invention at the top 24 of the lattice-profile
supporting casing 14 is illustrated in figure 12,
wherein the mechanical clinch or punch riveting joining
connection between the upper horizontal profile bar 22
and the vertical profile bar 20 can be made as
illustrated in figures 6, 7 and 8 in section C-D.
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Figures 13, 14, 15 and 16 show the upper horizontal
profile bar 22 butting against/bearing on the vertical
profile bar 20, wherein the horizontal profile bar 22
is supported via the shoulder 44 in figure 15 or via
the punched-out lower centering means 43 in figure 14.
Figure 16 shows a modified U-shaped upper horizontal
profile bar 22 with a bearing limb 45, which performs
the task of providing support on the vertical profile
bar 20. Figure 13 illustrates the horizontal profile
bar 22 bearing on the vertical profile bar 20 without
any vertical support.
The view of a lattice-profile crossover joint according
to the invention at the bottom 26 is illustrated in
figure 17, wherein the mechanical clinch or punch
riveting joining connection between the horizontal
profile bar 22 and the vertical profile bar 20 can take
place as illustrated in figures 6, 7, and 8 in section
C-D.
Figures 18, 19, 20 and 21 show the vertical profile bar
20 butting against/bearing on the lower horizontal
profile bar 22, wherein the vertical profile bar 20
additionally bears, in figure 20, on a T-shaped lower
horizontal profile bar 22 with a bearing limb 47 or, in
figure 19, on a punched-out shoulder 46. Figure 21
shows an L-shaped lower horizontal profile bar 22 with
two bearing regions 48, which perform the function of
supporting the vertical profile bar 20. Figure 18 shows
the horizontal profile bar 22 butting against the
vertical profile bar 20 without any additional vertical
support for the vertical profile bar 20.
List of designations
10 Pallet container
12 Inner container
14 Lattice-profile supporting casing
16 Base pallet
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18 Lattice-profile crossover point
20 Vertical profile bar
22 Horizontal profile bar
24 Lattice-profile crossover joint at the top
26 Lattice-profile crossover joint at the bottom
28 U-shaped bar profile
30 Clinch cavity
32 Clinch joining region
34 Semi-tubular rivet
36 Semi-tubular-rivet joining region
38 Solid punch rivet
40 Solid-punch-rivet joining region
42 Accommodating groove for horizontal profile bar
43 Punched-out centering means
44 Bearing region for horizontal profile bar
45 Bearing limb
46 Punched-out shoulder of vertical profile bar
47 Bearing limb
48 Bearing region for vertical profile bar
