EP1328447B1 - Pallet container - Google Patents

Abstract

The palletized tank comprises a thin-walled plastic tank supported by a close-fitting grid of metal bars (18, 20). These have constrictions (22) which allow the grid to deform without fracturing individual bars.

Description

The invention relates to a pallet container with a thin-walled inner container, preferably made of thermoplastic material, for storage and transport of liquid or flowable contents, with a plastic container as Support jacket tightly enclosing (grid) tube frame made of metal rods and with a Floor pallet on which the plastic container rests and with which the support shell is firmly connected.

State of the art:

Such pallet container z. B. with upper fill opening and lower drain valve in the plastic inner container and with a support jacket made of stable vertical tubes or with a welded from vertical and horizontal tube bars mesh tube frame are well known.
The document EP 0 695 694 A, for example, discloses in FIG. 2 a pallet container with a supporting jacket of stable vertical tubes with a round or oval cross-section. The vertical tubes are bordered at the top and bottom in a horizontal circumferential tube, the lower horizontal tube is attached by means of overlapping brackets on the bottom pallet.
A generic pallet container is known from US 5,678,688 A, in which the support grid for the plastic inner container consists of intersecting metal tubes with a round cross section. These round tube rods are provided at each intersection with an elongated indentation and welded together at the four points of contact (projection welding). These dents are pressed in even deeper than at the intersection points or the weld points themselves directly next to the intersections. This is intended to increase the elasticity of the support grid and to relieve the weld points of excessive stress peaks, in particular dynamic vibration loads. According to the task there, the static and dynamic loading capacity of the handling (stack load capacity and transport loads) of such pallet containers should be improved.
Furthermore, from DE 297 19 830 U another pallet container is known in which the support grid also consists of intersecting metal tubes which have a deviating from the circular cross-section tubular profile and are profiled so that an annular cross-section results with two projections, between which a flattened part is located. In each intersection of the profile tubes so four points of contact, which are welded together. The profile tubes are expressly designed to have a uniform cross-section over the entire length, and any lateral indentations or cross-sectional depressions should be expressly avoided as disadvantageous. The proposal should also focus on improving static and dynamic resilience. Furthermore, EP 0 755 863 A discloses a pallet container with a lattice tubular frame made of square tubular profiles. In this pallet container, the square tubes are only partially compressed in the region of the tube intersections to allow quadruple point contact and welding between the opposing planar side walls of the tubes by about 1 mm such that the flat sidewalls of the tubes recover after welding touch.
Finally, from DE 196 42 242 A a pallet container with a welded grid frame is known, the bars consist of an open bar profile, which is provided on the outer sides with flat, right angles angled outward flange edges, which welded against each other at the intersection of the bars are.
In the known pallet containers, the attachment of the lattice mantle on the bottom pallet, this can be formed as a flat pallet made of plastic, wood or steel tube frame, by means of or over the lower horizontal peripheral frame tube cross fasteners such. As screws, clips, brackets or claws. The attachment means are usually on the top plate or the top

Outside edge of the pallet nailed, donated, screwed or welded.
For an industrial application of the pallet containers, they must pass through an official approval sampling and fulfill certain quality criteria. So z. B. internal pressure tests and drop tests performed with filled pallet containers from certain heights, including at extremely low temperatures.
In this case, the worst case is a diagonal case on the lower pallet end face on which the bottom-side outlet valve of the inner plastic container is arranged. In such drop tests, it has been found that the inner container strives for ground impact to move relative to the bottom pallet. As a result of the kinetic impact energy, the grid bars are severely deformed, in particular at the impact front side and in the adjacent lateral peripheral areas, and individual attachment points of the grid jacket are torn off the floor pallet. The attachment of the lower edge of the tubular grid support jacket on the pallet so this is an essential problem area. Since the fixation of the lattice mantle is given only at a few punctual points, the grating casing is deformed and distorted very unevenly; The thin-walled plastic container may be damaged by torn pipe ends or torn fasteners.

Problem: Pallet containers or combination IBCs (IBC = intermediate bulk container) of the type mentioned here are used for the transport of liquids. They preferably have a filling volume of 1000 liters and consist of a pallet, a stable outer metal tube support jacket which is mounted on the pallet, and a resting on the pallet and inside the support shell tight-fitting inner container made of PE-HD, the upper feed opening and lower outlet fitting is provided. When transporting the pallet container from the manufacturer to the bottling plant, from the bottling plant to the customer, from the customer to the reconditioner, etc., the large-volume containers are often reloaded from trucks or large containers on conveyor belts and must be picked up by means of a forklift truck and dropped off again. This accident can not be ruled out with crash of the filled pallet container. And the transport vehicles can also crash. Also in the case tests for the approval tests, the containers are exposed to high loads, if they z. B. be dropped from a height of 1.9 m on a steel plate. In this case, no filling material may escape and the grating casing must still be connected to the pallet after the impact. The same applies to "Flexible IBCs" with a flexible inner container (eg fabric bag) for granular products.

As a starting point for the findings of the present invention were in extensive Screening of five known pallet containers available on the market the different types of comparative experiments described above employed, which sometimes found serious deficiencies, especially in the case tests were.

It is an object of the present invention to provide a pallet container with an improved falling strength in the design by simple means a better deformability of the grid cage at higher crash stress is ensured that for a single overuse. In particular, the lower outlet fitting of the inner container should be better protected as the most sensitive point of the container. A crashed pallet container must remain completely liquid-tight and easily picked up and handled by a forklift truck. In this case, the suitability of the pallet container for dangerous liquid or flowable products to the highest approval quality is to be made possible.
Solution : This object is achieved in the pallet container according to the invention with supporting jacket made of tubular steel bars by the kenzeichnende part of claim 1
For a container crash on the pallet end edge with the outlet valve, it is sufficient if the measures for a plastic deformation of the support jacket are provided only in the vertical tube rods.
In an embodiment of the invention, it is provided that the measure for a plastic deformation of the support jacket is designed as a bending point with reduction of the pipe cross-section. In this case, the reduction of the pipe cross-section at the bending point may be formed by asymmetrical molding of the pipe rod from one side; In a preferred embodiment, the reduction of the pipe cross-section at the bending point is formed by symmetrical recesses of the pipe rod from two opposite sides.
To protect the bottom-side outlet fitting is provided according to the invention that the indentations are formed to produce the bending points in the vertical tubes of the two longer side walls in a direction parallel to these side walls, while the indentations for generating the bends in the vertical tubes of the shorter Front wall (at the outlet valve) and the rear wall are formed in a direction perpendicular to the front / rear wall extending direction.
A particularly favorable deformation behavior in the event of a container crash is achieved if the indentations for producing the bending points are arranged directly above and / or below a crossing point with a horizontally extending tube rod.
In a preferred embodiment, the indentations for generating the bending points are formed differently deep. In this case, the depth of the recesses above the lowest horizontal circumferential tube rod, which is mounted on the bottom pallet, the largest and decreases towards the top of the other horizontally extending tubular rods (seen from below) gradually.
Finally, it may be provided in a simpler embodiment that the recesses are formed only in the vicinity of the intersections with the bottom three horizontal circumferential tubular rods.
As a special feature of the present invention is to emphasize that the tube profile is not pressed at the weld itself. The tube profile is in the vicinity next to the Verschweißstellen, ie at a distance from the welds in the long side walls in parallel and in the shorter side walls (with outlet fitting) at right angles partially pressed to a relation to the welds reduced bending resistance to relieve the welds in the intersection of the bars to cause shock.
The length of the indentations for producing the bending points is between 15 mm and 45 mm, preferably about 30 mm, and the depth of the indentations at the bending points should be between 15% to 50% of the pipe cross-section, preferably about 33%. Thus, the bending stiffness of the molded pipe cross-sections is only moderately reduced, but the susceptibility to cracking significantly reduced.

Figur 1

einen erfindungsgemäßen Palettencontainer in Seitenansicht,

Figur 2

den Palettencontainer gem. Fig. 1 beim Falltest,

Figur 3

den Palettencontainer gem. Fig. 2 im Moment des Bodenaufpralles,

Figur 4

den Palettencontainer gem. Fig. 3 nach Bodenaufprall,

Figur 5

einen vergrößerten Ausschnitt des seitlichen Gitterrahmens,

Figur 6

eine schematische Darstellung von deformierten Gitterrohr-Teilstücken,

Figur 7

eine schematische Darstellung von erfindungsgemäßer Gitterrohrausbildung,

Figur 8

eine schematische Darstellung der erfindungsgemäßen Gitterrohr-Teilstücke gem. Fig. 7 nach Falltest des Palettencontainers und

Figur 9

verschiedene Rohrstab-Profile unverformt - verformt,

The invention will be explained in more detail below with reference to further features and advantages with reference to embodiments schematically illustrated in the drawings and described. Show it :

FIG. 1

a pallet container according to the invention in side view,

FIG. 2

the pallet container acc. 1 during the drop test,

FIG. 3

the pallet container acc. 2 at the moment of the ground impact,

FIG. 4

the pallet container acc. 3 after ground impact,

FIG. 5

an enlarged section of the lateral grid frame,

FIG. 6

a schematic representation of deformed lattice tube sections,

FIG. 7

a schematic representation of inventive lattice tube formation,

FIG. 8

a schematic representation of the grid pipe sections according to the invention gem. Fig. 7 after drop test of the pallet container and

FIG. 9

various tube bar profiles undeformed - deformed,

In Figure 1 , the reference numeral 10 denotes an inventive pallet container having a thin-walled, blow-molded inner container 12 made of thermoplastic material (HD-PE) with upper filling opening and a tightly enclosing the inner container 12 lattice tube frame 14, the fixed - but detachable or interchangeable - Is connected to the bottom pallet 16. The dimensions of the bottom pallet 16, or the pallet container 10, be 1000 X 1200 mm. The illustrated side view shows the longitudinal side of the pallet container 10 with the bottom outlet valve in the plastic container 12. The (left) lower front edge of the bottom pallet 16 with the overlying outlet valve is the most sensitive point of the pallet container, which is exposed in approval tests greatest loads, especially in diagonal case , In the drawn circles, three grid crossing points are indicated by X, Y and Z, where the crossing point X in the plane A of the lowest horizontal lattice, the intersection Y in the plane B of the second horizontal lower lattice and the intersection Z in the plane C. of the third horizontal lattice bar seen from below - is arranged. These intersections will be considered in more detail below.

The test pallet container 10 shown in FIG. 2 is currently being subjected to a diagonal drop test for experimental purposes; Here, too, with the drawn circles X, Y and Z marked only in the excerpt (excerpts) places in the vertical and horizontal bars are marked, which are subject to great stress according to the drop test results, so that there is a cracking and in places a rod break. Of course, deformation occurs more or less in the entire lower grid frame area.
FIG. 3 shows the test pallet container 10 in accordance with FIG. Fig. 2 at the moment of the ground impact. The kinetic energy of the liquid filling material causes very considerable elastic and plastic deformation in the components inner container 12, grid frame 14 and bottom pallet 16. 4 shows the test pallet container 10 with permanent deformations after the drop test (according to FIG. In particular, the vertical profile bars 20 remain bent or kinked. The lattice frame 14 has already moved in the second lower lattice frame plane B 'over the lowest, mounted on the bottom pallet horizontal frame tube - by about 150 mm and a total (above) by about 200 mm from the impact edge of the bottom pallet 16.
It is clear from FIG. 5 that the marked crossing points Y and Z (as well as the respectively adjacent ones) have shifted laterally downwards according to a parallelogram kinematics; wherein in the horizontal tube bars 18 almost no and in the vertical tube bars 20 a very strong plastic deformation can be seen. This pronounced deformation in the region of the individual marked intersection points X, Y and Z is again emphasized schematically in FIG . It turns out that a vertical pipe rod 20 above an intersection always to the one side (in the drawing to the left) and below a crossing point always to the other side (in the drawing to the right) is bent. The occurring bending and shear stresses are low at the intersection Z, higher at the intersection Y and highest at the intersection X in the lowest lattice frame plane A. By attaching the lowest horizontal pipe bar 18 to the pallet 16 additional shear loads must be added in this area (intersection X).
The intersection point X is a particular weak point in the described case test, the vertical rod often tears or at higher heights it tears off completely. The cracking always takes place from the side of the greatest tensile stress. A sharp-edged crack in the lower tube rods can lead to damage to the inner container and leakage of the contents. Another vulnerability can exist in the Y area. There, the inner container by the horizontal bar B and the vertical rod, which is moved in the fall to 45 °, clamped and damaged.
Prior to development of the pallet container according to the invention five different available on the market known pallet container of the known types described above were subjected to the most accurate comparative stress tests (internal pressure tests, drop tests, vibration tests, compression pressure test or stack load capacity). In the screening tests, particularly frequent weak spots in individual grid frame areas have emerged for the drop test. The extreme deformations of the vertical bars always arose immediately at the welding points. In practice, it has been shown that the welds usually survive the stresses of the drop tests, but - due to material embrittlement and additional shear loads in the bending area - often occur directly adjacent to the welds on or tears of the vertical bars.

The measures according to the invention for improving the deformation behavior of a crashed pallet container are shown schematically in FIG . The vertical profile bar 20 is provided near the weld points in the intersections with indentations 22, wherein between two grid intersection points always at least one indentation 22 is provided. In this case, the vertical profile bar 20 is reduced in its width, that is pressed or constricted (in grid shell deformation level of the drop test).
Mode of action: By indenting the vertical bars next to the welding points, a predefinable weak point arises at the desired location with a certain distance from the welds, absorbs the bending stress that occurs and relieves the welding areas of bending stresses. The pipe profile is pressed in at a small distance next to the welding points (about 3 to 5 mm remain undeformed), that is, the bending takes place in an area that is not brittle from welding. Due to the design of the vertical bars with the described recesses (reduction in cross section), the described disadvantages of the prior art only occur at considerably higher loads or fall heights.
The depth of the formed by forming desired bending points can amount to a maximum of about 50% of the pipe cross-section. The Einformungstiefe should total (even with bilateral indentation) in the range of 15% to 50% of the width of the tube cross section, preferably about one third (33%). Thus, the bending stiffness of the molded pipe sections is only moderately reduced, but the susceptibility to cracking or even complete Rohrabriß lowered considerably.
The indentations are formed on the side of the welding points comparatively steep and flattening on the other side. An indentation of 5 mm (= approx. 33%) is usually sufficient for a tube with a height or width of 15 mm; As a result, the maximum of the bending load is kept away from the weld and it remains overall a sufficiently high pipe stiffness is maintained. This is important to the lateral deflection of the grid frame z. B. at Innendruckbeaufschlagung to minimize.

Figure 8 shows schematically the intersections A, B 'and C' acc. Fig. 7 after drop test of a pallet container according to the invention. The bends of the vertical grid bars 20 are here in the region of the indentations 22. Due to the reduced bending stiffness in the indentations 22, the deformation of the vulnerable crossing point or the welding points is shifted away in the desired bending point and at the weld points itself occurs no more cracking.
As shown schematically at the bottom left in FIG. 8 on a vertical pipe section 20, a indentation 22 may be formed only on one side of the rod. In a preferred embodiment, however, a desired bending point is realized by symmetrical bilateral indentation 22 (necking).

Finally, in an exemplary embodiment, six different tube profiles with corresponding indentations are shown schematically in FIG. 9 next to each other. The technical teaching according to the present invention is not limited to a specific pipe profile.
The undeformed "normal" bar profile is drawn in these partial representations in each case - in dashed representation - and the point of the invention essential indentation in continuous lines.
FIG. 9a shows a preferred closed trapezoidal tube profile 24 (M) (height / width = 18/15 mm) with high performance values in the individual approval tests carried out. A possible embodiment of the lateral indentation is designated by 24 '.
FIG. 9b shows a known open section trapezoidal bar profile 26 (R) with a possible indentation 26 '.
FIG. 9c shows a known round-tube profile 28 (S) (diameter 18 mm) with a possible indentation 28 ', the cross-section being reduced from both sides and additionally from above and below.
Figure 9d shows another known round tube profile 30 (VL) (diameter 20 mm) with a possible indentation 30 '; Here, the cross-sectional reduction is formed only from the sides.
Figure 9e shows a square tube profile 32 (F) (height / width 18 mm) with a possible cross-sectional reduction 32 'by indentation from all four sides.
FIG. 9f shows a square tube profile 34 with another possible indentation 34 ', which is formed in a symmetrical shape like a four-leaf clover.

Of course, the invention can also be applied to flexible IBCs with metal tube support jacket and Z. B. tissue inner container realized for granular products become.

References list

10

pallet container

12

Inner container HD-PE

14

Trellis-supporting shell

16

bottom pallet

18

Horizontal Bar

20

Vertical Bar

22

indentation

24

Trapezoidal profile

26

Open profile

28

Round tube section

30

Round tube section

32

Square tube profile

34

Square tube profile

A

1st lower lattice plane

B

2nd lower lattice plane

C

3rd lower lattice plane

X

Crossing point (A)

Y

Crossing point (B)

Z

Crossing point (C)

Claims (11)

1. Pallet container (10) having a thin-walled inner container (12) made of thermoplastic material for the storage and transportation of liquid or free-flowing contents, having a tubular frame which is made of metal bars and tightly encloses the inner container (12) as a supporting casing (14), and having a base pallet (16), on which the inner container (12) rests and to which the supporting casing (14) is fixed, characterized in that, for the case where a container is dropped, special measures in the form of a bending location, with reduction in the tube cross section at certain predeterminable locations, are taken only in the vertical tubular bars (20) of the supporting casing (14), these allowing plastic deformation of the supporting casing (14) without individual tubular bars (20) rupturing or breaking off, in which case, in order to produce the bending locations in the vertical tubular bars (20) of the two longer side walls, shaped recesses (22) are formed in a direction running parallel to the longer side walls.
2. Pallet container according to Claim 1, characterized in that the reduction in the tube cross section at the bending location is formed by shaped recessing (22) of the tubular bar (20) from one side (non-symmetrically).
3. Pallet container according to Claim 1, characterized in that the reduction in the tube cross section at the bending location is formed by shaped recessing (22) of the tubular bar (20) from two opposite sides (symmetrically).
4. Pallet container according to Claim 1, 2 or 3, characterized in that the shaped recesses (22) for producing the bending locations in the vertical tubular bars (20) of the shorter front wall (at the discharge valve) and rear wall are formed in a direction running perpendicularly to the front/rear wall.
5. Pallet container according to Claim 1, 2, 3 or 4, characterized in that the shaped recesses (22) for the bending locations in the vertical tubular bars (20) are arranged between two crossover locations with the horizontal tubular bars (18).
6. Pallet container according to one of the preceding claims, Claims 1 to 5, characterized in that the shaped recesses (22) for producing the bending locations are arranged directly above and/or beneath a crossover location with a horizontally running tubular bar (18).
7. Pallet container according to one of the preceding claims, Claims 1 to 6, characterized in that the shaped recesses (22) for producing the bending locations are formed with different depths.
8. Pallet container according to one of the preceding claims, Claims 1 to 7, characterized in that the depth of the shaped recesses (22) is greatest above the lowermost horizontally encircling tubular bar (18), which is fastened on the base pallet (16), and decreases in a stepwise manner in the upward direction (as seen from beneath) to the further horizontally encircling tubular bars (18).
9. Pallet container according to one of the preceding claims, Claims 1 to 8, characterized in that the shaped recesses (22) are only formed in the vicinity of the crossover locations with the three lowermost horizontally encircling tubular bars (18).
10. Pallet container according to one of the preceding claims, Claims 1 to 9, characterized in that the length of the shaped recesses (22) for producing the bending locations is between 15 mm and 45 mm, preferably approximately 30 mm.
11. Pallet container according to one of the preceding claims, Claims 1 to 10, characterized in that the depth of the shaped recesses (22) at the bending locations is between 15% and 50% of the tube cross section, preferably approximately 33%.

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