EP0515389B1 - Stackable drum - Google Patents

Abstract

The invention concerns a large-capacity stackable drum with a substantially cylindrical side wall (3) and top and bottom ends (32, 34). To improve the stackability in particular the long-term stackability an internal hydrostatic pressure which supports the side wall is initially produced, when stacking several drums one on top of the other, in the gas space above the content and in the contents, of the drums stacked underneath, by virtue of the elastic flexibility of the top (32) and/or the bottom (34) of the drum, until a reduced stacking load acting through the top rim or grip ring (38) of the drum into the drumwall (30) is produced or support provided through the bottom rim or grip ring (40).

Description

The invention relates to a stackable drum, preferably a large-volume drum made of thermoplastic, e.g. PE (polyethylene), or steel, with an essentially cylindrical barrel wall and top and bottom barrel bottoms, in which a circumferential gripping ring (handling ring) is provided in the vicinity of at least the top barrel bottom and at least one of the two disc-shaped flat barrel bottoms above a cross-sectionally almost conical or curved in the axial direction outwardly projecting over the barrel gripping ring piece is connected to the barrel wall.

Plastic sheet drums are generally known, the top and bottom flat barrel bottoms of which are connected to the cylindrical barrel wall via an obliquely conical or rounded ring part, e.g. from the German utility model DE-U-87 05 916. Since in such barrels the circumferential gripping rings mostly also take on the function of roller tires, they extend essentially in the radial direction from the outer barrel wall; furthermore there is a comparatively large axial projection of the barrel bottoms in the axial direction outwards or a considerable spacing of the barrel bottoms over the obliquely conical ring part from the gripping rings projecting outwards. An axial force load on these gripping rings is only possible to a very limited extent, if at all, since this would lead to the bending of the L-shaped rings protruding radially from the barrel wall and to buckling of the barrel walls. The hand rims have no influence on the stackability of such drums. Another such plastic barrel with upper and lower gripping ring and projecting conical ring parts adjoining the top and bottom of the barrel is known from FR-A-2 585 330. When such drums are stacked, the stack load is taken up only after deformation of the conical or arched ring pieces of the flat drum bottoms via a hydrostatic internal pressure build-up; the barrel jacket is not loaded in the axial direction directly or only after the handling ring has been deformed (cf. FIGS. 1 and 2).

Since barrels are generally transported and stacked on pallets and these pallets usually do not have a flat support surface on the underside, but two or three parallel, spaced-apart floor boards, there is normally no uniform support force on the top floor of the stacked barrel when stacked.

Such a one-sided or uneven loading can easily lead to one-sided yielding of the lower barrel and thus increases the risk of the stacked barrels falling over to the side.

Furthermore, other large-volume sheet drums are generally known, in which the gripping rings are formed by an axial extension of the barrel wall or by retracted, recessed barrel bottoms. With such barrels, e.g. Even with a conventional steel drum, the stack load is only taken up by the rigid, rigid drum jacket. These barrels therefore have a relatively thick barrel jacket, provided they are made of plastic, which allow little or no elastic axial deformation; A hydrostatic internal pressure is generally not built up in such a drum. If an internal pressure nevertheless develops, the flat barrel bottoms bulge outward without being able to take over the function of partial stacking load support. In principle, it does not matter whether the barrel is empty or full, and whether the bung is tightly closed or open. Another disadvantage of such a barrel is therefore a correspondingly high empty or operating weight.

It is therefore an object of the present invention to improve the stackability of large-volume drums, and here in particular the long-term stacking method, while at the same time making possible a saving in drum material and a reduction in empty drum weight.

This object is achieved in that the height of the protrusion of at least one barrel bottom outwards via the associated barrel gripping ring is one to five times the wall thickness of the barrel wall.

This configuration ensures that when barrels are stacked one on top of the other in the stacked barrel, which is filled with a filler (eg liquid) and sealed tightly, in the upper residual gas space under the top shelf and in the filler first by elastic compliance of the top shelf projecting outwards or / and sub-floor, an internal hydrostatic pressure between 0.1 and 0.3 bar, preferably about 0.16 bar, is built up in a defined, reproducible manner before there is a reduced introduction of stacking loads into the outer barrel edge or handling ring.

Due to the inventive design of the barrel with near the barrel end face from the barrel jacket integrally molded upper barrel ring and / or lower barrel ring, which essentially represent an axial extension of the barrel jacket, and with a flat top and a flat underbody opposite the axial End faces of the carrying and transport rings protrude outward in the axial direction, and they are connected to the barrel jacket via conical, annular outer regions, which is very advantageous holds a stack load in the vertical barrel gripping rings, which are formed essentially axially to the barrel wall, with the flange edge projecting radially outwards only after a pronounced defined internal pressure build-up inside the barrel. First of all, a defined hydrostatic internal pressure is built up and only after a radial prestressing does the axial loading into the barrel jacket take place via the gripping rings, whereby the stack load acting upon the axial loading of the gripping rings is distributed over a wider circumferential part of the barrel wall. Due to the prevailing internal pressure, the risk of denting the barrel casing is also shifted towards a higher axial load. This means that such drums can absorb a significantly higher stacking load and at the same time the risk of overturning is significantly reduced. Furthermore, it is possible in this way, for example with a predetermined, assessable load for the stacked drum with about 900 kg in a triple drum stack of, for example, 220 1 drums, that the wall thickness of the drum wall and thus the empty drum weight can be reduced accordingly. In the case of a steel barrel, this makes it possible to use a steel sheet of, for example, 0.9 mm compared to a previous steel sheet with a wall thickness of 1.0 mm.

For example, the wall thickness of a plastic drum can be reduced from 3.8 mm to 3.3 mm to 3.2 mm. This advantageously results in a reduction in the operating weight of an empty barrel, e.g. 9.0 kg to approx. 8.5 kg and a material saving of the plastic raw material.

Due to the additional stabilizing internal pressure they use, the barrels according to the invention have a much more favorable long-term stacking behavior than other known plastic barrels. Due to the axial pressurization of the barrel bottoms and their support on the respective pallet bottoms, the barrel jacket only has to bear a reduced stacking load.

The invention is explained and described in more detail below on the basis of exemplary embodiments schematically illustrated in the drawings.

• Figur 1 ein bekanntes Kunststoff-Faß mit hoch über den äußeren Greifring hinausstehendem Oberboden,
• Figur 2 das in Fig. 1 dargestellte bekannte Kunststoff-Faß im untergestapelten Belastungsfalle,
• Figur 3 ein anderes bekanntes Faß mit weit über den Oberboden überstehenden oberem Greifring,
• Figur 4 das in Fig. 3 dargestellte bekannte Faß im untergestapelten Belastungsfalle,
• Figur 5 ein erfindungsgemäßes Kunststoff-Spundfaß,
• Figur 6 das in Fig. 5 dargestellte Kunststoff-Faß im untergestapelten Belastungsfalle,
• Figur 7 einen Ausschnitt eines erfindungsgemäßen Fasses im Zustand steigender Belastung,
• Figur 8 das in Fig. 7 dargestellte Faß im Endzustand einer untergestapelten Belastung,
• Figur 9 ein weiteres erfindungsgemäßes Deckelfaß und
• Figur 10 das in Fig. 9 dargestellte Deckelfaß im untergestapelten Belastungsfalle.

Show it:

• FIG. 1 shows a known plastic drum with an upper floor protruding high above the outer gripping ring,
• FIG. 2 the known plastic drum shown in FIG. 1 in the stacked load case,
• FIG. 3 another known drum with an upper gripping ring protruding far beyond the top surface,
• FIG. 4 the known drum shown in FIG. 3 in the stacked load case,
• FIG. 5 shows a plastic sheet drum according to the invention,
• FIG. 6 the plastic drum shown in FIG. 5 in the case of a stacked load,
• FIG. 7 shows a section of a barrel according to the invention in the state of increasing load,
• FIG. 8 the drum shown in FIG. 7 in the final state of a stacked load,
• Figure 9 shows another lid barrel according to the invention and
• Figure 10 shows the lid barrel shown in Fig. 9 in the stacked load case.

In FIG. 1, the reference number 10 denotes the barrel jacket of a generally known, comparatively thin-walled plastic barrel, in which the top bottom 12 of the barrel is connected to the barrel jacket 10 via an obliquely conical ring piece 14. In the transition area from the conical ring bag 14 into the barrel jacket 10, a circumferential, upper L-shaped grip ring 16 is arranged. The barrel is filled with a liquid (filling material) 18 approximately up to the height of the gripping ring 16, a gas space 20 remaining free below the upper floor 12, which projects high above the outer gripping ring 16.

In the case of the load shown in FIG. 2 for this known barrel, an internal pressure build-up takes place in the gas space 20 and the filled-in liquid 18 by lowering the top plate 12. An axial load on the gripping ring 16 is normally not provided. However, as soon as there is an axial load on the gripping ring with increasing load or deformation of the top surface - this usually does not take place evenly in the practice, but e.g. due to a narrow pallet underbody, mostly partially or one-sided - this cannot absorb axial forces or transfer them into the barrel wall, but bends outwards or downwards and leads to premature dents 22 of the barrel jacket in this area and thus to an increased risk of overturning of the corresponding barrel stack. After relief, this handling ring is no longer safe and manageable.

Another already known drum made of comparatively thick-walled plastic is shown in FIG. Here, the upper gripping ring 24 extends far in the axial direction in extension of the barrel wall 28 beyond the barrel top 26.

As can be seen from FIG. 4, in this drum an axial stacking load can only be introduced via the upper end face of the gripping ring and can be absorbed by the drum wall 28. If the load is excessive, elastic deformation of the gripping ring 24 and compression of the barrel body can occur due to elastic deformation. As a result, when an internal pressure is built up, the barrel top 26 (and barrel bottom) bulges outwards without external resistance (no stack load being applied). Such drums made of thick-walled plastic are expensive because of the material involved and have a high operating weight.

A bung barrel according to the invention with a comparatively thin-walled, essentially cylindrical plastic barrel wall 30, top floor 32 and bottom floor 34 is shown in FIG. In the edge region of the flat, flat top floor 32, a molded-in filling / emptying bung 36 is arranged. An upper gripping ring 38 and a lower gripping ring 40 are provided in the vicinity of the barrel wall 30. Barrel top 32 and barrel bottom 34 are connected to the barrel jacket via a conical ring piece 42, 44. This results in a circumferential free space 46 behind the gripping rings 38, 40 for engaging the claws of a corresponding drum gripper or a crane hook. Characteristic of the invention here is that in the barrel according to the invention the upper and / or lower barrel bottom 32, 34 protrude beyond the end face 48, 50 of the respective gripping ring 38, 40. 5, the protrusion 52 of the upper drum base 32 over the upper gripping ring 38 and the protrusion 54 of the lower drum bottom 34 over the lower gripping ring 40 is approximately twice as much as the wall thickness of the drum wall 30.

In Figure 6, the case of loading of the barrel according to the invention is shown schematically by a pallet 56 placed on it, which exerts a compressive force on the barrel with a stacking load P _s . Due to the protruding barrel bottom design, a defined reproducible internal pressure P _i of approximately 0.16 bar is built up inside the filled and tightly closed barrel, so that the axial loading of the barrel jacket 30 takes place only after a radial prestress. This advantageously gives a superposition of partially compensating axial and tangential tensile stresses and axial compressive forces.

Another positive effect is illustrated in FIGS. 7 and 8. When loading begins (Fig. 7) - e.g. through a stacked barrel - and compression of the top surface 32 with the beginning of elastic deformation of the conical lid-ring piece 42, an additional stabilizing compressive force acts in the radial surface direction - illustrated by arrow 58 - from the inside onto the barrel jacket 30 in the connection area 60 between the barrel jacket 30 and the upper gripping ring 38 and the cover ring piece 42. With a larger load, e.g. two stacked barrels (Fig. 8), a substantial part of the compression force is introduced into the barrel wall in the axial direction via the front edge 48 of the upper gripping ring 38.

Due to the prevailing internal pressure P _i and the additionally stabilizing pressure force from the cover ring piece 42 - both of which counteract a buckling or buckling of the barrel jacket inwards - the stacking property and in particular the long-term stacking behavior of the barrel according to the invention is considerably improved. Due to the internal pressure acting on the barrel bottoms and their support on the pallet bottoms, the barrel jacket only has to bear a significantly reduced stacking load, as a result of which material fatigue, aging or decreasing long-term stiffness with loss of strength like with conventional plastic barrels does not occur at all or only very much much later.

Another embodiment of a barrel according to the invention is shown in the form of a lid barrel (wide-necked container) in FIG. 9 and FIG. 10. Here, the upper gripping ring 38 is arranged in the peripheral region of the barrel cover 62. The drum cover 62 is supported with its lower peripheral flange 64 on a jacket flange 66 projecting from the outer drum wall 30. The upper edge of the barrel casing 30 engages in a U-shaped recess in the barrel cover 62, in which a sealing ring 68 is arranged. By means of a clamping ring 70 which simultaneously overlaps the cover flange 64 and the casing flange 66, the cover 62 can be prestressed in a gastight and liquid-tight manner on the barrel opening or barrel wall and can be securely closed.

In the unloaded case (FIG. 9), the surface of the barrel cover 62 has a protrusion 52 of approximately three times the wall thickness of the cover or the barrel casing over the end edge 48 of the upper gripping ring 38. In the event of a load (FIG. 10), the lid 62 is pressed inwards by the height of the protrusion, so that the internal pressure P _i has built up in the barrel and axial compressive forces from the upper gripping ring 38 via the cover flange 64 and the jacket flange 66 in the axial direction in the barrel jacket 30 can be initiated. In the area 72 close to the flat cover surface, the conical ring part 42 has a defined crumple zone, for example formed by a circumferential groove profile, which improves the elasticity or resilience of the drum cover in this area.

Here too, due to the internal overpressure, the barrel casing is stiffened, so that this lid barrel also has better stacking properties and improved long-term stacking behavior due to its special design.

Because of the large contact diameter (equal to the diameter of the gripping ring 38), there is a better distribution of the compressive force in the barrel wall, less overall deformation and greater lateral stability.

In a modification of the invention, the barrel gripping rings could, for example, also be attached, shrunk, glued or / and welded onto the outer barrel jacket as separate prefabricated ring pieces.

Furthermore, the barrel design according to the invention could also be implemented in a bung barrel in that the entire upper floor and / or lower floor with the respective gripping ring as a separate one prefabricated part (eg injection molded part) and then welded to the cylindrical barrel jacket. The increase in the stackability, in particular the long-term stackability, of large-volume drums with at least one circumferential drum gripping ring arranged on the outer drum wall in the vicinity of the corresponding drum bottom and at least one drum bottom projecting outward over the drum gripping ring in the axial direction is achieved functionally by stacking one above the other of barrels in the lower gas-tight barrels in the remaining residual gas space and in the filler or the liquid, initially by means of elastic compliance of the top plate and / or the bottom plate, an internal hydrostatic pressure between 0.1 and 0.3 bar, preferably about 0.16 bar, is built up before a vertical stacking load is introduced into the barrel wall via the outer barrel edge or gripping ring and thus an improved stacking behavior, in particular long-term stacking behavior, can be achieved. If the circumferential gripping ring, which is formed in the axial direction in the extension of the barrel wall, is subjected to punctual loading, the stacking load which occurs is advantageously distributed over a larger peripheral region of the barrel wall.

Claims (9)

1. A large-volume, stackable barrel having a substantially cylindrical barrel wall (30) and upper and lower barrel heads (32, 34), wherein in the vicinity of at least the upper barrel head (32) there is an encircling grab ring (38) (handling ring) provided on the outer barrel wall (30) and wherein at least one of the two disc-shaped barrel heads (32, 34) is connected to the barrel wall (30) via an annular portion (42, 44) which - when viewed in cross-section - projects outwards in the axial direction in a substantially conical or convex manner, the height of the projecting portion (52, 54) of at least one barrel head (32, 34) above the grab ring (38,40) being one to five times the wall thickness of the barrel wall (30) or the barrel head (32, 34), characterised in that when the barrel is loaded by a stack at least one of the conically outwardly projecting annular portions (42, 44) of the upper head (32) and/or of the barrel lower head (34) is resiliently deformable to such an extent that a supporting hydrostatic pressure between 0.1 and 0.3 bar, preferably approximately 0.16 bar, can firstly be builtup in the barrel interior before the stack load can be transmitted into the outer barrel wall (30) via the outer grab ring (38, 40) or barrel edge.

2. A barrel in accordance with Claim 1, characterised in that a resiliently deformable annular portion (42) is solely provided on the upper barrel head (2) and an upper barrel grab ring (38) is solely provided in the extension of the substantially cylindrical barrel wall (30), and the lower head (34) is constructed flush with the lower barrel grab ring (40) or becomes the barrel wall (30) in a substantially direct manner.

3. A barrel in accordance with Claim 1 or 2, characterised in that the height of the projecting portion (52) of the upper barrel head (32) above the upper barrel grab ring (18) is approximately three to four times the wall thickness of the barrel wall (30) or the barrel upper head (32).

4. A barrel in accordance with Claim 1, characterised in that the height of the projecting portion (52) of the upper head (32) above the upper barrel grab ring (38) is approximately three times the barrel wall thickness (30) and the height of the projecting portion of the lower head (34) above the lower barrel grab ring (40) is approximately one to two times the barrel wall thickness (30).

5. A barrel in accordance with Claim 1, 2, 3 or 4, characterised in that the substantially conical annular portion (42, 44) which determines the height of the projecting portion (52, 54) of the barrel head (32, 34) above the barrel grab ring (38, 40) is in the form of a resiliently deformable crumple zone, e.g. with encircling annular groove profiles.

6. A barrel in accordance with Claim 1, 2, 3, 4 or 5, characterised in that the grab ring (38) is formed by an annular portion (75) extending substantially in the axial direction, in the extension of the barrel wall (30) and having a flange edge (74) directed radially outwards, a free space (46) - wedge-shaped when viewed in cross-section - being formed between the inner surface of the annular portion (75) of the grab ring (38) and the conical annular portion (42, 44) of the barrel head (32, 34).

7. A barrel in accordance with any one of the preceding Claims 1 to 6, characterised in that the upper edge of the plug (36) is level with or flush with the outer surface of the upper barrel head (32) or is sunk in slightly lower.

8. A method of increasing the stackability, in particular the long-term stackability, of large-volume barrels with at least one encircling barrel grab ring arranged on the outer barrel wall in the vicinity of the appropriate barrel head and with at least one barrel head projecting outwards above the barrel grab ring in the axial direction, characterised in that when stacking barrels of this type on top of one another

- in the lower barrels, closed in a gas-tight manner, in the remaining residual-gas-space (76) and in the filling material or the fluid (18) there is firstly built up an inner hydrostatic pressure between 0.1 and 0.3 bar, preferably approximately 0.16 bar, through resilient flexibility of the upper head (32) and/or of the lower head (34), before

- a vertical stack load is transmitted into the vessel wall (30) via the outer barrel edge or grab ring (38) and consequently improved stack behaviour, in particular long-term stack behaviour, can be obtained.

9. A method in accordance with Claim 8, characterised in that with localised loading of the encircling grab ring (38,40) which is formed in the axial direction in the extension of the barrel wall (30), the arising stack load is distributed over a larger circumferential region of the barrel wall (10).

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