CA2411207A1

CA2411207A1 - Palette container

Info

Publication number: CA2411207A1
Application number: CA002411207A
Authority: CA
Inventors: Dietmar Przytulla
Original assignee: Individual
Current assignee: Mauser Werke GmbH
Priority date: 2000-05-25
Filing date: 2001-05-21
Publication date: 2002-11-22
Also published as: HUP0302022A3; CN1444536A; NO20025648D0; MXPA02011546A; BR0111277B1; MXPA02011521A; HUP0302064A3; EP1289853A2; EP1289852B1; HUP0302022A2; AU2001269033B2; NO20025649D0; CA2409852C; NO20025648L; ATE326399T1; HU227866B1; DK1289852T3; CN1221448C; KR20030015252A; CZ20024238A3

Abstract

The invention relates to a palette container (10) comprising a thin-walled rigid inner container (12) made of thermoplastic synthetic material for storing and transporting liquid or flowable filling products. The inventive palette container also comprises a grid tube frame (14) which, as a support casing, closely surrounds the plastic container (12), and comprises a base palette (16) on which the plastic container (12) rests and to which the support casing is firmly attached. The grid tube frame (14) consists of vertical and horizontal tubular rods (30, 32) that are welded to one another at points of intersection (36). Several prior art palette containers exhibit substantial shortcomings (grid tube fatigue fracture) when subjected to prolonged dynamic vibrational stress that occurs, for example, during persistent stresses caused by the transport on roads of poor quality. The aim of the invention is to achieve an adapted optimal vibrational elasticity in order to improve the stability of the grid frame while providing a sufficient degree of flexural strength. To this end, the tubular rods (30, 32) have a closed profile (18) with a particular trapezoidal cross-section.

Description

PALLET CONTAINER
The invention relates to a pallet container having a thin-walled inner receptacle made from thermoplastic material for the storage and transport of fluid or free-flowing goods, wherein the plastic container is closely surrounded by an outer cage jacket as a supporting casing of crossed pipe bars and a bottom pallet on which the thermoplastic receptacle is supported and which is firmly connected to the supporting casing.
Such pallet containers with welded pipe bar support jackets are generally known, as for example in EP 0 734 987 A (Sch). The pipe bar support jacket of the pallet container disclosed there consists of pipe bars having a circular profile, that are highly compressed at the welded intersection points. From DE 297 19 830 U1 (vL) another pallet container is known having pipe bars with a different cross sectional configuration, but which is intended to possess specifically a uniformly shaped cross section throughout the entire length of the bar without any dimples respectively any cross section reducing dents. A further pallet container with a cage that has open profile pipe bars is known from the DE 196 42 242. There, straight surfaces laterally flanged outwards, are welded together in the area where the cage bars intersect. The open profiled cage bars possess a slight torsional stiffness and make it difficult to manually handle the pallet container due to their thinness and the relatively sharp-edged outer flange. Furthermore, various pallet containers with cage bars having a square shaped cross section are known in the prior art.
The attachment of the cage jacket at the bottom pallet may be configured as flat a pallet from plastic or wood or as a steel tube frame and is usually realized by attachment means as for example, screws, brackets, clamps or grips that engage with the lower horizontal and circumferentially extending cage bars.
These attachment means are either nailed, riveted, screwed or welded to the upper plate or the upper outer edge of the pallet.
For industrial use or when the pallet containers are utilized in the chemical industry, they have to pass a governmental approval inspection and fulfill various quality controls. For example, the filled pallet containers have to undergo interior pressure tests and drop tests from specific heights. Pallet containers or combination -IBCs (IBC=Intermediate Bulk Container) of the type discussed here -with a filling volume of usually 1000 liters-, are preferably used in the transport of liquids. Particularly when transporting filled combination-IBCs by truck, considerable gushing motions of the fluid container load occur that are due to transport shocks and the movement of the transport vehicle- particularly, on bumpy roads, thereby exerting constantly changing pressure forces on the interior receptacle walls which in turn lead to radial vibrational motion in square shaped pallet container (dynamic continueous vibrational stress). Depending on the configuration of the cage jacket during long transports over bad roads, stress is building up so that the cage bars get fatigued and break. Consequently, such pallet containers are not suitable, for example for export to the USA , or for multiple usage.
The drawbacks of the embodiment in the afore-described EP 0 734 967 A
are that the circular pipe profile of the horizontal and vertical cage pipe bars, specifically in the area of the intersecting points, are prone to considerable deformation specifically at the welding locations and thus exhibits a markedly reduced section modulus as compared to the other areas. Additionally, the pipe bar profile is still deeper dimpled next to the dimples for the welding points thus, further weakening the bar, and whereby through welding, the area of the dimpled pipe bar profile the material becomes brittle.
It is an object of the present invention to obviate the afore-described drawbacks and to propose a pallet container with improved transport strength that provides with simple constructional means a cage jacket with improved resistance against transport stress respectively, against the long-term vibrational motion stress. On the one hand, the pallet container should be suitable for transporting dangerous fluids or free-flowing loading goods up to the highest standard of allowable levels; and on the other hand, while fulfillimg normal transport needs, it should be possible to configure the cage jacket with fewer vertical andlor horizontal cage bars without loss in its mechanical stability.

SOIUtIOn In accordance with the invention, this object is attained by providing a pallett container with a cage jacket of vertical and horizontal steel pipe bars wherein the cage bars have a trapezoid shaped cross section with a closed profile and having longer and shorter parallel extending side walls and two straight side walls which extend obliquely relative to each other, and which, starting from the longer of the parallel side walls that are extending obliquely towards each other, connect to the shorter wall, and wherein the two straight side walls that are extending obliquely relative to each other form a crown angle of approximately 20°
to 45°, preferably about 36°. The trapezoid shaped closed profile of the pipe bar possesses a high bending section modulus and and a high torsion-section modulus due to the profile sidewalls being positioned in a slightly oblique manner relative to each other. This is realized particularly when the height to width (HIB) ratio of the trapezoid shaped tube profile is in the range of 0.8 to 1.0, preferably about 0.86. With the pallet container according to the invention, a cage jacket can be realized which sustains forseeable normal transport stress and which is configured having a total of only 5 instead of 6 of the horizontal cage bars but without noticable loss of mechanical load carrying capacity.
In one embodiment of the invention, partially in the area the intersection of two cage bars, the longer parallel side wail of the cage bar with the trapezoid shaped profile is dimpled inwardly along a length of approximately twice the width of a cage bar in such a manner, that the two outer longtitudinal edges form a convexity so that four points are formed at each intersection of the vertically and horizontally extending cage bars that are firmly joined after welding, whereby in each of the cage bar intersections the (longer) parallel walls facing each other are not contacting each other even after being welded.
In a preferred embodiment, the longer of the parallel walls of the cage bar with a trapezoid shaped profile is dimpled inwardly along its entire length (_ continuous longitudinal indenting or profiling) in such a way, that the two outer longitudinal edges are formed with an outwardly extending convexity (bulging), wherein at each intersection of the horizontally and vertically extending cage bars four contact point are formed which are firmly connected after being welded, so that the (longer) opposing parallel walls are at a distance from each other even after being welded and without contacting each other. In prototypes, the trapezoid shaped cage bars which are dimpled along their entire length have proven especially outstanding in their use.
In a variation of the embodiment, it may be provided that the longer parallel wall of the trapezoid profiled pipe bar is dimpled inwardly only partially in the area of an intersection and the longer parallel wall of the other trapezoid shaped pipe bar is inwardly dimpled along the entire length. This may prove to be already entirely sufficient for the average stress load. The depth of the profiling dimple of the longer parallel wall amounts to about once to twice that of the wall thickness of the profiled pipe bar (about 1 mm to 2mm); in an actual pallet container, where the profiled pipe bar wall thickness is 1 mm and the depth A of the dimple is also 1 mm, so that after welding - whereby the contact points of the crossed cage bars melt into each other by about 1 mm - at each intersection, the long parallel walls facing each other are spaced apart from each other by about 1 mm and are not in contact with each other even after welding. This is particularly important because oftentimes pallet containers are stored outdoors and are thus exposed to the elements of weather. By providing a distance between the cage bars at the points of welding, accumulating rain water can easily dry off and formation of rust is thereby substantially prevented. If the welding surfaces were in contact, the formation of rust would be unavoidable leading to extensive rusting of the cage bars within a short time.
In a further and special configuration of the invention, at least a dimple is provided at the side of the longer parallel wall of the trapezoid shaped pipe bar laterally at a distance to each of the welding points. This dimple reduces the height of the pipe bar H thereby relieving ,the dynamic vibrational stress and the critical peaks of the various bending stresses that bear on the sensitive welding points. In accordance with the invention, it is further provided that at each side of the trapezoid shaped pipe bars, next to the welding point, a dimple is provided, which is spaced at a distance of at least one tenth of the width B of the pipe bar.
Thus, during occurrence of the dynamic vibrational stress, the critical tension peaks are shifted away from the welding points to adjacent areas at a distance thereto.
By means of this special configuration, a substantial reduction in static or dynamic stress on the welding connections is realized when providing the pipe bars with dimples laterally at a distance to the welding points by which reduction of the peak-stress is realized, whereby the welding points are provided not in a deformation zone and thus retain their high flexural strength. The following particulars for the fore-going invention apply: In contrast to the known pipe bar profiles and according to the invention, the pipe bars are not partially dimpled at the welding points, but the respective dents or dimples are provided at a distance from the welding points at the same side andlor the opposite side of profile in order to reduce the bending section modulus relative to the intersecting points and to relieve the welding points of the cage bars of static and/or dynamic stress. The trapezoid shaped profile is configured so it can be dimpled easily and without extensive material displacement. Dimpling (= denting, respectively indenting, as desired formation of "vibration elements") of the pipe bars is provided at only specific regions of the pipe bars whereby relief against vibrational stress and the fluctuating flexural tension peaks on the welded intersection or the four welding points is realized. When welding one pipe bar together with a second pipe bar, stiffening of the pipe with an attending material brittleness occurs at that loaction making the pipe bar particulaly sensitive at this point against vibrational stress.
Considerable vibrational stress, which is present, for example, during transport by truck can lead in the shortest time to breaking of the welding points or the pipe bars itself at the welding points. In accordance with the invention, the cage bar-support jacket is configured such that the "wanted vibration points" are not exactly at the intersecting points or in the proximate zone thereof but at least a short distance from the welding points of the intersection. The desired vibration points which are established by forming the dimples are in any event less than 50% of the cross section of the pipe bar. They are arranged in the range of 10 % to 45%
of the height of the pipe bar cross section, preferably at about 113 (33%).
The flexural strength of the dimpled pipe bars is thereby somewhat reduced, but the susceptability to fracturing due to fatigue is considerably reduced.
The invention is explained and described in greater detail hereinafter with reference to embodiments, which are illustrated in the drawings. It is shown in:
FIG. 1 a front view of a pallet container according to the invention;
FIG. 2 a side view of a testing-pallet container;
FIG. 3 an sectional illustration on an enlarged scale of the trapezoid shaped pipe bar profile according to the invention at a pipe bar intersecting point;
FIG.4 a further sectional illustration on an enlarged scale of a preferred trapezoid shaped pipe profile at a pipe bar intersecting point;
FIG. 5 a schematic sectional illustration of a hydrodynamic pressure effect of a fluid load on the container side- wall;

FIG. 6 a horizontal partial sectional illustration of a point of greatest outward deflection of the cage;
FIG.7 an enlarged illustration of an intersection of pipe bars with dimples;
FIG. 8 a trapezoid shaped cross section of a pipe bar according to view D of FIG. 7;
FIG. 9 a trapezoid shaped cross section of a pipe bar along line C-C
of FIG. 7;
FIG. 10 a square shaped profile of a cross section of a pipe bar -unstressed;
FIG. 11 the square shaped profile of a cross section of a pipe bar according to FIG. 10- over-stressed;
FIG. 12 a profile of a pipe bar according to the invention - unstressed;
FIG. 13 the profile of a pipe bar according to the invention according to FIG. 12 - stressed;

FiG. 14 another pipe bar profile according to the invention;
FIG. 15 a further pipe bar profile according to the invention; and FIG. 16 a partial top view of a corner arc of the pipe profile according to the invention.
Shown in FIG. 1, referenced with numeral 10, is a pallet container according to the invention which shows a thin-walled blow-molded rigid inner receptacle 12 made of thermoplastic material (HD-PE) with an upper input opening and a cage of intersected pipe bars 14 closely enveloping the inner receptacle, and which is firmly - but detachably or interchangeably connected to the bottom pallet 16. The front view as depicted exhibits the narrow side of the pallet container 10 with an exit valve disposed at the plastic receptacle 12 near the bottom. The lower front edge of bottom pallet 16, here shown in configuration as a wooden pallet (US Runner), with the exit valve 18 situated above, represents the most vulnerable point of the pallet container, which is exposed to the greatest stress during approval testing, especially during the diagonal drop test. The special configuration of the cage bars with dimples (cf. Fig. 7) are shown in the circles.
Prior to the development of the pallet container according to the invention, five different pallet containers known and available on the market were submitted to the precise comparative stress tests (intertior pressure test, drop tests, vibration tests, test for pressure capacity upset, resepctively testing stacking capacity). In serial vibration tests during simulation of long haul truck transport on bad roads, certain especially frequently occurring weak points in various cage jackets could be isolated.
The test pallet container 10 (here shown without the elasticity promoting dimples) shown in FIG. 2, which for testing purposes was also deliberately submitted to continueous overload testing, is shown with circles drawn to illustrate those points marked at the horizontal and vertical cage bars, which fail and begin to break first according to the comparative testing results during dynamic vibration stress, (cf. FIG. 10, 11 ).
FIG. 3 shows an area of intersection of a closed pipe bar profile 18 in accordance with the invention, a trapezoid shaped cross section, a longer wall and a shorter wall extending parallel to each other 20, 22 and the two straight walls 24 extending obliquely relative to each other, and beginning from the longer parallel wall 22 that extend obliquely connect to the shorter wall 20, whereby the two straight side walls of profile 18 which extend obliquely relative to each other form a crown angle 26 in the range of 20° to 45°, preferably about 36°. The ratio of height to width of the trapezoid shaped profile of the pipe bar is in the range from 0.8 to 1.0, - preferably about 0.86. Due to the relatively great height of the trapezoid shaped profile (without a bend in the oblique side walls) a correspondingly high flexural stiffness is realized, and due to the closed and compact configuration of the trapezoid shaped profile, the pipe bars exhibit an improved torsional stiffness as compared to pipe bar profiles that are configured with a circular profile or those having an open profile. The distance of the intersection of the extended horizontal axis of the walls 24 extending obliquely relative to each other at crown angle 26 is about the height H of the profile or, measured beginning from the longer parallel wall 20 is about 2H. The distance can be in the range of 0.75 to 2.5 H.
The trapezoid shaped profile 18, preferably utilized is depicted in FIG. 4. In a simple manner, the longer parallel wall 22 is only partially inwardly dimpled in the area of the intersection of two pipe bars in such a manner that at each of the two outer longitudinal edges a convexity 28 is formed that bulges outwardly, so that at each intersection of the horizontally and vertically extending pipe bars, four contact points are formed, which after being welded, are firmly connected to each other, whereby the (longer) parallel walls 22 opposite each other in each pipe bar intersection are still spaced from each other even after welding.
In an especially preferrred embodiment, the longer parallel wall 22 is dimpled inwardly along the entire length of the ripe bars, whereby the two outer longitudinal edges are provided with an outwardly bulging convexity 28. The pipe bar having the continuously dimpled trapezoid shaped profile 18 has proven outstanding and is being manufactured from a pipe template having a diameter of 18mm (56.55mm in circumferential length). The depth of dimple of the longitudinal profile should be about once or twice that of the wall thickness of the pipe bar (about 1 mm to 2mm); in a fully formed pallet container the wall thickness of the pipe bar is 1 mm and the depth of the dimple 1 mm. The welding at each of the four contact points at each intersection of the pipe bars is carried out by means of electrical resistance pressure welding. When carrying out the four-point welding, the crossing cage bars are being pressed together about 1 mm, so that the opposing parallel walls 22 in each intersection are still distanced from each other by about 0.5 mm to 2mm, preferably, about 1 mm and are not in contact with each other even after being welded. (distance A= 1 mm). This is a partcularly important aspect, since pallet containers oftentimes are stored outdoors and are exposed to the weather. By distancing the cage bars from each other at the welding points, rain water which might accumulate there dries off by exposure to air and thus, rusting is substantially prevented. Welding surfaces that are abutting each other are inevitably prone to formation of rust, which can lead to heavy rusting of the entire cage in the shortest time. Illustration of the cross section also clearly shows that the width of the (longer) parallel wall 22 that remains between the outwardly bulging edges 28 is approximately the same as the width B1 of the opposite (shorter) parallel wall 20.
The schematic representation of FIG. 5. illustrates the changing deforming deflection of the cage jacket due to dynamic vibrational stress: The hydrostatic interior pressure of the fluid goods load - illustrated in the right hand side in FIG. 5 causes the maximal cage deflection Da, D; occurring approximately at the level of the center of gravity S of the loaded goods, which means at about 33% of the cage height, and at that level the vibration amplitude toward the outside is approximatly two times that of the inside, which is the reason the greatest danger of crack formation in the cage pipe bars during vibrational stress is in the area of the lower half of the cage.
The schematic representation of a partial sectional view in FIG. 6 illustrates the horizontal cross section at the location of the maximal deformation effect Da and D;. There is no interference of vibrational deflection directed towards the outside, while inside the fluid column encounters the opposite side wall. The lower circumferential horizontal cage bars 30 are thus submitted to great bending stresses particularly, in the vicinity of the corner bends 38.
FIG. 7 shows - in an interior view of the cage - the intersection 36 of a horizontal pipe bar 30 with that of a vertical pipe bar 32. In the intersection 36, the four welding points are indicated. The trapezoid shaped pipe profile of horizontal bar 30 and that of the vertical bar 32 is provided each with one dimple 34 at each side exactly next to the intersection 36, respectively the four welding points, whereby the dimples 34 are distanced to the point of intersection 36 by at least one tenth of the pipe bar width B. View D of the non-deformed trapezoid shaped profile 18 is shown in FIG. 8 and an illustration of the dimple 34 along the line C-C
is shown in FIG. 9. The dimples 34 in the pipe bar can be made on the side of the ("longer") parallel wall 22 or/and on the side of the opposing ("shorter") parallel wall 20. Thus, numerous variations may thereby be realized, so that between two cage bar intersections at least two dimples may be provided at the outer side of the trapezoid shaped profile or/and two dimples may also be provided at the inner side. Significant with these embodiments is however, that the pipe bars are not dimpled or deformed directly at the point of intersection or respectively at the welding points, but only at a distance to them. When reducing the height H of the profile, the depth T of one dimple 34 should be kept low if possible, i. e. in the range of 15°l° to 50%; in a preferred embodiment, the depth T of the dimple is about 33% of the height H of the profile. The longitudinal extension of dimple along the bar should be in the range of about one and one half to three times the width B of the profile, in a preferred embodiment, the longitudinal extension of an dimple 34 is about twice that of the profile width B.
FIG. 10 shows an unstressed pipe profile of the known type having a square shaped profile along the entire length of the bar. After already a relatively short period of dynamic vibrational stress, formation of a crack is seen on the horizontal bar 30' directly at the intersection, respectively at the welding points, as is illustrated in FIG. 11.
The formation of cracks or respectively, the tearing of the cage bars always occurs in the area of highest pull tensions, or at the location where the greatest bulging of the cage jacket occurs. The vertical pipe bars are arranged at the inside of the cage jacket and the horizontal pipe bars are arranged at the outside.
Cracks and fracture points always occur in the area of the intersection directly next to the welding points (cf. circled views in FIG. 2). Cracks start forming at the vertical pipe bars - and relative to the jacket- always travel from the outside to the inside and always start on the inside of the horizontal bars travelling to the outside.
In comparative tests, it has been found that the cage jackets made from cage bars with an open profile and provided with flat outwardly angled edges exhibit good stacking capacity because the welding points are relativley far part from each other within the intersection, but they react most unfavorable to vibrational stress.
As compared to the square shaped pipe profile, in FIG. 12, a closed trapezoid shaped pipe profile 18 in accordance with the invention is shown with two dimples 34 in a horizontal bar 30. As illustrated in exaggerated manner in FIG.
13, crack formation does not occur even after prolonged exposure to vibrational stress. On the one hand, this is due to the welding points in the intersecting area being free of weakness-inducing dimples and therefore very stable, while on the other hand, the dimples 34 reduce the bending section modules and function as a kind of "bending hinge" when located at least at a small distance from the intersection thereby acting to prevent the peak tensions impacting upon the sensitive welding points and deflecting them towards more distant flexible areas.
The special problems in constructing a particular embodiment of a cage jacket is that the vertical and horizontal cage bars should be as stable and rigid as possible in order to prevent excessive bulging of the pallet container which is, for example, exerted by interior pressure; and on the other hand, a high bending section modulus should be provided to counteract constant dynamic vibrational stress, whereby the two afore-mentioned criteria operate in opposite directions.
While considering favorable, i.e. low production costs, an optimal solution must be found. According to the latest trends according to the invention, the known pallet containers having cage bars with an even profile along the length of bar, as for example according to DE 297 19 830 U1 may be suited as storage containers but are not suitable as containers for carrying dangerous fluid loads submitted to dynamic vibrational stress.
The afore-cited patent publication is based on the prior art insofar as the known pallet container has a cage jacket made from pipes with a circular cross section that are provided with dimples at least at the welded pipe intersections. A
statement on page 2 of that patent disclosure which states "....by using a profiled pipe (there) according the invention (without any localized dimples) local tension accumulation is avoided...." does not correctly state the latest trends in the present invention and simply shows that the effect of the opposite connection between flexural strength and vibration elasticity have not been taken into account when such cage jackets of pallet containers are submitted to transport stress.
The depth T of the dimples 34 in the trapezoid shaped profile according to the invention are approximately between 25% and 50%, preferably approximately 33% of the height H of the pipe bar profile. An dimple by 5mm (=33%) is generally sufficient at a pipe having a height of 15mm whereby the vibrational stress at the welding points is either kept low or is elimintated while retaining a sufficiently high rigidity in the pipe. This rigidity is important in order to keep the vibration amplitude of the lateral bulging of the vibrating cage at a low level.
FIG. 14 illustrates an embodiment having two dimples 34 at the side of the pipe bar profile facing away from the welding points with the short parallel wall 20, and which - as is shown in Fig. 15 - illustrates a modified and particularly useful variation of that embodiment. The trapezoid shaped pipe profile 18 is provided wiith dimples 34, each at the side of the shorter parallel wall 20 and on the side of the longer parallel wall 22 laterally next to a intersectiing point 36 in such a manner so that the dimples are exactly opposite each other. The dimples are spaced here at a distance of approximately one tenth of the width B of the pipe bar profile from the intersecting point 36. Placing the dimples 34 in each of the parallel extending side walls 20, 22, particulalry enhances the "hinge effect" or the elasticity of the pipe profile.
According to the technical teaching of the present invention, the configuration of the dimples 34 in the horizontal and vertical pipe bars 30, 32 can be of different depth depending on the intensity of the dynamic stress expected to bear on the cage jacket 14. Thus, in accordance with specific demand or need, while retaining sufficient flexural strength, the optimal vibrational elasticity in the horizontal and vertical pipe bars can be controlled in various areas of the cage jacket, for example in the longer side walls, or the shorter front and rear walls of the pallet container.
FIG. 16 illustrates a further important embodiment for reducing the bad effects of the dynamic vibrational stress of the horizontal pipe bars. In the region of the 90° bent corner areas and parallel to the vertical, the horizontal pipe bars 30 of the cage jacket 14 are flattened such that they also act as a hinge-type "bending joint". fn the comer areas, the horizontal pipes need not possess a high bending resistance, of greater importance here is a higher elasticity. Particularly favorable test results were realized with pallet containers that have horizontal pipe bars 30 which are flattened in the corner areas 38 of support jacket 14 from the inside and/or from the outside by at least one fourth of the height H of the diameter of the profile 18. In one of the embodiments actually built, the horizontal pipes in the lower region of the cage jacket are flattened from the inside by about 20 %
and form the outer comer arch by about 35%, while of flattenings in the upper region of the cage jacket are configured so they are incrementally reduced.
At this point it should be pointed out, that the essential features of the invention are rendered schematically and in an exaggerated way in the patent drawings, which should not be interpreted as limiting but merely for purposes of illustration and better understanding by the viewer.

It is understood that the variations as shown can be combined in various ways and that other combinations are also within the spirit of the invention.
The above-presented possible variations, particularly the lower region of the cage jacket can be provided with different means for realizing sufficient flexural strength with an optimal suitable pipe bar elasticity.

REFERENCE NUMERAL LIST
pallet container A distance (22-22) 12 inner receptacle HD-PE B width profile pipe 5 14 cage jacket B~ reduced width (22) 16 bottom pallet H height profiled pipe 18 trapezoid profile S load-point of gravity short parallel wall T depth dimple (34) 22 long parallel wall Da outer deformation 10 24 straight slanted wall D, inner deformation 26 crown angle 28 convexity (bulging) horizontal bar 32 vertical bar 15 34 dimple (30, 32) 36 intersection (30, 32) 38 corner arc (30) flattening (38)

Claims

1. Pallet container (10) having a thin-walled rigid inner receptacle (12) from thermoplastic plastic material for storage and transport of fluid or free-flowing goods, and closely surrounded by an outer cage jacket (14) acting as a support casing and a bottom pallet (16) on which the thermoplastic receptacle is supported and which is firmly connected to the support casing;
wherein the cage jacket (14) consists of vertical and horizontal hollow bars (30, 32) welded together at intersecting points (36), characterized, in that the hollow bars (30, 32) exhibit a closed profile (18) with a trapezoid shaped cross section and with a longer and a shorter wall extending parallel to each other and two straight walls (24) extending at an oblique angle relative to each other, and, beginning from the longer parallel wall (22) extend and connect to the shorter wall (20), whereby the two straight and obliquely angled side walls of the hollow bar profile (18) form a crown angle (26) in the range of 20° and 45°, preferably about 36°; and wherein the trapezoid-shaped hollow bar profile (18) is provided adjacent to a welding point laterally at each side thereof with a dimple (34) each at least at a distance to the welding point of about a tenth of the width of the hollow bar (B).

2. Pallet container according to claim 1, characterized, in that the height/width-ratio (H/B) of the trapezoid hollow bar profile (18) is in the range of 0.8 and 1.0 -preferably about 0.86.

3. Pallet container according to claim 1 or 2, characterized, in that the longer parallel wall (22) of the trapezoid hollow bar profile (18) in the area of the intersection (36) of two hollow bars (30, 32) are dented inwardly in such a manner that a convexity (28) (bulging) is formed at the two outer longitudinal edges so that at each intersection (36) of the horizontally and vertically extending hollow bars (30, 32), four contact points are formed, which are firmly connected to each other after welding, wherein the longer walls facing each other in each hollow bar intersection (36) are still spaced apart from each other after welding and are not in contact with each other.

4. Pallet container acording to claim 1 or 2, characterized, in that the longer parallel wall (22) of the trapezoid profile (18) is dented inwardely along the entire length of the pipe, such that at each of the two outer longitudinal edges a convexity (28) (bulging) is formed and that at each intersection (36) of the horizontally and vertically extending hollow bars (30, 32) four contact points are formed, which are firmly connected to each other after welding, wherein at each intersection of the hollow bars the longer parallel walls (22) facing each other are still spaced apart after welding and are not in contact with each other.

5. Pallet container according to claim 3 or 4, characterized, in that the longer parallel wall (22) of the trapezoid shaped profile of a hollow bar (18) is indented inwardly in the area of the intersection, and in the other hollow bar (32, 30) the longer parallel wall (22) of the trapezoid shaped profile (18) is indented inwardly extending along the entire length of the hollow bar.

6. Pallet container according to claim 1 through 5, characterized, in that the distance (A) between the two longer parallel walls (22) of the intersecting hollow bars (30, 32) after welding is about 0.5mm to 2mm, preferably about 1 mm.

7. Pallet container according to one of the preceding claims 1 through 6, characterized, in that the (longer) parallel wall (22) remaining between the outwardly extending convexities (28) (bulgings), when seen in cross section of the trapezoid profile (18) exhibits the same width (B1) as the opposite (shorter) parallel wall (20).

8. Pallet container according to one of the preceding claims 1 through 7, characterized, in that the trapezoid hollow profile (18) has at least one dimple (34) at the side of the longer parallel wall (22) which is at a distance and laterally next to a welding point.

9. Pallet container according to one of the preceding claims 1 through 8, characterized, in that at least two dimples (34) are provided between the two intersecting points (36) at the shorter of the parallel walls (20), that is, at the reverse side of the welding point, or/and at least two dimples (34) are provided at the side of the longer parallel walls (22), that is at the side of the welding points.

10. Pallet container according to one of the preceding claims 1 through 9, characterized, in that the depth (T) of dimple (34) which reduces the height of the profile (H) is kept rather small, that is about between 15% and 50%, preferably about 33% of the height of the profile (H).

11. Pallet container according to one of the preceding claims 1 to 10, characterized, in that the longitudinal extension of a dimple (34) - in longitudinal direction of the hollow bar - is about between one and one half and three times the width of the profile (B), preferably, about twice that of the profile width (B).

12. Pallet container according to one of the preceding claims 1 through 11, characterized, in that at the side of the shorter parallel wall (20) and at the side of the longer parallel wall (22), each trapezoid hollow bar profile (18) is provided with a dimple (34) each laterally next to an intersection (36), so that the dimples (34) are exactly opposite each other, wherein the dimples (34) are at least at a distance of about one tenth of the width of the hollow bar profile (B) from the intersection (36).

13. Pallet container according to one of the preceding claims 1 through 12, characterized, in that the dimples of the pipe bars (30,32) have a different depth in dependence on the intensity of the dynamic vibrational stress in various areas of the cage jacket (14) or/and in the horizontal and vertical hollow bars (30,32)

14. Pallet container according to one of the preceding claims 1 through 13 characterized, in that the horizontal hollow bars (30) are flattened in parallel- respectively in vertical direction in the corner areas (38) that are bent at a 90°
angle.

15. Pallet container according claim 14 characterized, in that in the corner areas (38) that are bent at a 90° angle, the horizontal hollow bars (30) have a flattened configuration from the inner side or/and from the outer side by at least one forth of the height (H) of the cross section of the profile (18).