EP0633200B1 - Pallet container and method of making it - Google Patents

Abstract

The pallet container (1) for liquids has an exchangeable inner container (2) made of sheet metal, an outer casing (6) of latticework and a pallet (9) which is designed as a bottom tray (10) and receives the bottom (16), designed as a drainage bottom, of the inner container in a positive-locking manner. The inner container (2) of sheet metal, preferably of dual-walled design, is welded together from a casing (11), a bottom part (12) and a lid (13). To produce the inner container, a rectangular sheet-metal blank is bent to form a tubular body whose abutting edges are welded longitudinally. The tubular body is stretched to form a casing of rectangular cross-section. A circumferential bead with a V-shaped cross-section is then moulded in each case into the two end regions of the casing with spacing from its edges which are subsequently trimmed. The deep-drawn, tray-shaped bottom part is then fitted precisely with a bent edge onto or attached to the outer flank of the one bead of the casing, and the bottom part is fixed to the casing. The lid is mounted on the casing in the same manner. The bottom part and the lid are welded to the casing. To form a smooth transition between the casing and bottom part on the one hand and the casing and lid on the other hand, the transition regions between the casing and the bottom part and the casing and the lid are widened by applying pressure to the inner container inserted in a supporting mould. <IMAGE>

Description

The invention relates to a method for producing single and double-walled inner containers made of sheet steel or an inner plate made of corrosion-resistant stainless steel and an outer plate made of normal steel for pallet containers with an outer lattice jacket made of metal, a base tray made of sheet metal as a pallet for the positive reception of the inner container and a pallet frame Made of metal, wood or plastic to support the floor pan.

The need to save raw materials and the legal environmental protection regulations are forcing the relevant industry to fill liquids for transport and storage in large-volume pallet containers that are available on the market and are designed as reusable containers, instead of as previously in barrels with a significantly lower capacity.

So far, mainly pallet containers of the type described above with an inner container made of plastic have been used for the transport of liquids, such as those e.g. are known from DE 42 06 945 C1. Compared to single-walled sheet steel containers and double-walled sheet steel containers according to DE 92 15 689 U1, which are preferably used for the transport of dangerous liquids such as chlorinated hydrocarbon, the plastic containers have the following disadvantages:

The formation of barrier layers on the outside and inside of the plastic inner container caused by fluorination cannot allow liquids such as solvents and solvent-containing liquids to permeate into the plastic prevent so that the cleaning options for the pallet container are limited. According to legal regulations, flammable liquids must not be stored in pallet containers with a plastic inner container, and flammable liquids with a flash point below 0 ° C must not be transported with such containers. Finally, the inner container has a limited stability against external impact or shock loads.

The invention has for its object to develop a method for the economical and inexpensive manufacture of single and double-walled inner containers made of sheet steel for pallet containers with a grid jacket.

This object is achieved according to the invention by the manufacturing method according to the patent claim.

The pallet container with an inner container made of sheet steel can be used for the transport and storage of liquids that are required in industry for a wide variety of purposes. In particular, the container can be used for the transport and storage of flammable liquids. The container is suitable for use in the food industry due to the fact that it can be emptied completely and that it can be cleaned optimally due to the smooth formation of the inside of the jacket, bottom and lid and the transitions between jacket and bottom part and jacket and lid due to the liquid nests. The double-walled construction of the inner container with Inner sheets made of stainless steel as corrosion protection and outer sheets made of normal steel, which have the supporting function of the side walls and the bottom of the container, allow a reduction of the wall thickness prescribed for corrosion-resistant, single-walled sheet metal containers from 2.5 to 3 millimeters by up to 50% to 1.2 to 1.5 millimeters. The inner container made of sheet metal, in conjunction with the metal grid jacket, has great stability, which ensures the highest level of security for the pallet container against external impact and shock loads and multiple stackability of the container. The economical manufacturing process for the inner container made of sheet metal enables the production of inexpensive pallet containers with high quality.

Fig. 1

eine prespektivische Darstellung eines Palettenbehälters mit einem Innenbehälter aus Blech, einem Gittermantel und einer als Bodenwanne ausgebildeten Palette,

Fig. 2

einen Längsschnitt und

Fig. 3

einen Querschnitt durch den Bodenbereich des Palettenbehälters nach Linie III-III der Fig. 2 in vergrößerter Darstellung,

Fig. 4

eine abgeänderte Ausführungsform des Innenbehälters in perspektivischer Darstellung,

Fign. 5 bis 7

drei Verfahrensstufen bei der Herstellung des Mantels des Innenbehälters aus Blech,

FIg. 8

eine perspektivische Darstellung des mit Sicken zum Anschweißen des Bodenteils und des Deckels versehenen Blechmantels des Innenbehälters,

Fign. 9 und 10

die Verbindung des Blechmantels mit dem Bodenteil und dem Deckel aus Blech durch eine Rollennahtschweißung,

Fig. 11

die formschlüssige Verbindung des Mantels mit dem Bodenteil,

Fig. 12

das Glätten der Übergänge zwischen Mantel und Boden sowie Mantel und Deckel des Innenbehälters durch Aufweiten in einer Stützform und

Fig. 13

eine Einzelheit der Stützform im Bereich der Bodenschweißnaht des Innenbehälters nach dem Aufweitvorgang.

The invention is explained below with reference to drawings. It shows

Fig. 1

a perspective view of a pallet container with an inner container made of sheet metal, a lattice jacket and a pallet designed as a floor pan,

Fig. 2

a longitudinal section and

Fig. 3

3 shows a cross section through the bottom area of the pallet container according to line III-III of FIG. 2 in an enlarged view,

Fig. 4

a modified embodiment of the inner container in a perspective view,

Fig. 5 to 7

three process stages in the production of the jacket of the inner container from sheet metal,

FIg. 8th

a perspective view of the beads for welding the bottom part and the lid provided sheet metal jacket of the inner container,

Fig. 9 and 10

the connection of the sheet metal jacket to the base part and the sheet metal cover by means of roller seam welding,

Fig. 11

the positive connection of the jacket to the bottom part,

Fig. 12

smoothing the transitions between the jacket and the bottom and the jacket and lid of the inner container by widening in a support mold and

Fig. 13

a detail of the support form in the area of the bottom weld seam of the inner container after the expansion process.

The pallet container 1 used as a disposable and reusable container according to FIGS. 1 to 3 for the transport and storage of liquid goods of different types has as main components an exchangeable inner container 2 made of sheet metal with a rectangular outline and rounded corners, which has a filler neck 3 which can be closed by a lid 4 with a clamping ring and a further neck 5 in Bottom area is equipped for connection of a tap and flushing tap, an outer jacket 6 of intersecting vertical and horizontal bars 7, 8 made of metal and a flat base tray 10 made of sheet metal 9 with Euro-standard length and width dimensions for the positive reception of the inner container 2 .

The inner container 2 made of sheet metal is welded together from a jacket 11, a bottom part 12 and a cover 13. Jacket 11, bottom part 12 and lid 13 of the double-walled inner container 2 consist of a thin inner plate 14 made of corrosion-resistant stainless steel and an outer plate 15 made of mild steel, the thickness of which is greater than that of the inner plate 14 (FIG. 9).

In deviation from the described embodiment, the inner container 2 can also be designed as a single-walled container.

The bottom part 12 of the inner container 2 has a drain bottom 16 which runs with a slight slope from the rear edge 12a to the front edge 12b of the bottom part 12 and which also slopes slightly from the two side edges 12c, 12d of the bottom part 12 towards the center of the bottom. In this way, the bottom 16 of the bottom part 12 of the inner container 2 forms a flat drainage channel 17 which is slightly inclined to the connecting piece 5 in the front edge 12b for connecting a dispensing and flushing tap, preferably a ball or flap tap.

The inclined to the drain bottom 16 of the inner container 2, deep-drawn sheet metal material from the bottom tray 10 of the pallet 9 with a drain gutter 17 of the inner container 2 corresponding flat central groove 18 has a downwardly drawn outer support edge 19 and in the direction of and transverse to the central groove 18 Stiffening beads 20a, 20b, the reasons 21 of which lie in a common plane 22-22. The stiffening beads 20a, 20b and the central channel 18 form chambers 23 which are open at the bottom in the floor pan 10, and the outer support rim 19 forms a circumferential, hollow support collar 24 on the floor pan 10. The floor pan 10 of the pallet 9 designed in this way is characterized by good damping capacity and high rigidity both when subjected to vibrations caused by driving vibrations transmitted by the transport vehicle and surge vibrations emanating from the liquid transport goods and also when subjected to external impact or shock loads, so that the pallet container 1 meets the high requirements with regard to the required transport and accident safety fully sufficient.

An all-round outer edge strip 25 is angled from the outer support edge 19 of the floor pan 10 and forms a subframe with a stiffening strut 26 fastened centrally under the floor pan 10.

The grid jacket 6 fixed by the circumferential support collar 24 of the floor pan 10 of the pallet 9 is supported with the lower, horizontally circumferential grid bar 8 or a lower end profile on the edge strip 25 of the floor pan 10, and the grid jacket 6 is over the lower, horizontal grid bar 8 screwed together with the floor pan 10 and the center 27 and corner feet 28 onto the pallet frame 29 designed as a tubular steel frame.

The grid jacket 6 is stiffened by an upper frame 30 which is screwed to the grid jacket and protects the inner container 2 from above.

The modular design of the pallet container allows a simple and quick assembly of the container, a simple exchange of the inner container made of sheet metal for an inner container made of plastic and a space-saving and inexpensive storage as well as a correspondingly inexpensive transport of the components.

In the inner container 31 according to FIG. 4, the drain bottom 16 falls slightly from all edges 12a-12d of the bottom part 12 towards the center, and the bottom 16 has a central removal and rinsing opening 32 with a connection for a removal and rinsing device, wherein the removal opening 32 is assigned a corresponding opening in the bottom of the base trough, the shape of which is adapted to the drain base of the inner container.

To produce the double-walled sheet metal jacket 11 of the inner container 2, a rectangular sheet-metal cutout (not shown) made of stainless steel and normal steel sheet is bent into a tubular body 33, and its abutting edges 33a, 33b are then longitudinally welded, for example on a frame welding machine (FIG. 5).

The tubular body 33 is pulled onto a stretching press 34, the expansion jaws 35, 36 of which have the shape of the inner container 2 in the region of its narrow sides (FIG. 6). After the pipe body 33 has been drawn on, the expanding jaws 35, 36 of the stretching press 34 are moved apart by a pressure medium cylinder 37 (FIG. 7). The tubular body 33 assumes the shape of the sheet metal jacket 11. The tubular body 33 is drawn onto the stretching press 34 in such a way that the longitudinal weld seam 38 of the tubular body 33 comes to rest on one of the narrow sides 39 of the sheet metal jacket 11.

A circumferential bead 40, 41 with a V cross-section is formed in the two end regions of the jacket 11 at a distance from the jacket edges 11a, 11b, e.g. rolled up or pressed in (Fig. 8).

The two outer edge strips 11c, 11d of the jacket 11 adjoining the beads 40, 41 are cut to size.

Subsequently, the deep-drawn, trough-shaped bottom part 12 with a beveled edge 42 fits snugly onto or onto the outer flank 40a of the one bead 40 of the jacket 11, and the bottom part 12 is attached to the jacket 11.

In the same way, the deep-drawn or pressed cover 13 is then fitted with a bent edge 43 onto or onto the outer flank 41a of the other bead 41 of the casing 11, and the cover 13 is attached to the casing 11.

Bottom part 12 and cover 13 are welded to the jacket 11 in a liquid-tight manner, preferably welded by roller seams (FIGS. 9 and 10).

The edge strips 11c, 11d of the container casing 11 projecting over the folded edges 42, 43 of the base part 12 and the cover 13 are folded over the folded edge edge 42 and the cover edge 43, and those of the outer flanks 40a, 41a of the beads 40, 41 in Jacket 11 and the edge strips 11c, 11d formed column 44 for receiving the bottom 42 and the lid edge 43 are pressed together, as shown in Fig. 11 for the connection of the jacket 11 and bottom part 12.

In the last stage of the production process, the annular gaps 45 formed between the jacket 11 and the base part 12 or cover 13 of the inner container 2 are eliminated, which can form liquid pockets in which liquid accumulates during emptying, which form pathogenic germs when the pallet container is used in the food industry can.

To eliminate the annular gaps 45, the inner container 2 is introduced into a support form 46 which is designed such that the inner transition regions 47 between jacket 11 and base part 12 and jacket 11 and cover 13 can expand to a limited extent when the container 2 is subjected to hydraulic or pneumatic pressure , wherein the outwardly projecting outer flanks 40a, 41a of the two beads 40, 41 in the container casing 11 and the edges 42, 43 of the bottom part 12 and the lid 13 which abut against them are clamped from the outside in order to tear open the bottom 48 and to avoid the welded lid seam 49 (FIGS. 12 and 13).

The increased pressure prevailing in the inner container 2 is expediently used for the leak test of the container.

Claims (1)

1. A method of making single and double wall inner containers (2) of steel sheet or a sheet consisting of an inner sheet (14) of corrosion-resistant stainless steel and an outer sheet (15) of ordinary steel, for pallet containers (1) with an outer mesh jacket (6) of metal, a bottom tray (10) of sheet metal formed as a pallet (9) to receive the inner container (2) mating therein, and a pallet frame (29) of metal, wood or plastics material for supporting the bottom tray (10), characterized by the following method steps:

   a) bending a rectangular piece of sheet metal of the kind of sheet recited above into a tubular body (33);

   b) longitudinally welding the abutting edges (33a, 33b) of the tubular body (33);

   c) stretching the tubular body (33) into a jacket (11) with a rectangular or square cross-section;

   d) indenting a peripheral corrugation (40, 41) with a V-cross-section in each of the two end regions of the jacket (11), spaced from its edges (11a, 11b);

   e) cutting off to size the two outer edge strips (11c, 11d) of the jacket (11) adjoining the corrugations (40, 41);

   f) snugly fitting the deep-drawn, tray-shaped bottom part (12) with an out-turned edge (42) on to or against the outer flank (40a) of the one corrugation (40) of the jacket (11) and fastening the bottom part (12) to the jacket (11);

   g) snugly fitting the deep-drawn cover (13) with an out-turned edge (43) on to or against the outer flank (41a) of the other corrugation (41) of the jacket (11) and fastening the cover (13) to the jacket (11);

   h) welding the bottom part (12) and cover (13) liquid tight to the jacket (11);

   i) turning the edge strips (11c, 11d) of the container jacket (11) projecting beyond the turned out edges (42, 43) of the bottom part (12) and the cover (13) over the turned out bottom edge (42) and cover edge (43) and pressing together the gap (44) formed by the outer flanks (40a, 41a) of the corrugations (40, 41) in the jacket (11) and the edge strips (11c, 11d) for reception of the bottom and cover edges (42 and 43);

   j) widening out the inner transition regions (47) between the jacket (11) and the bottom part and between the jacket (11) and the cover (13) of the container (2) placed in a supporting mould (46) to remove the annular gaps (45) formed between the jacket (11) and bottom part (11) and between the jacket (11) and cover (13), by pressurising the container (2) and

   k) testing the tightness of the container (2) under internal pressure.

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