EP0453429B1 - Barrel with bulges - Google Patents

Description

The invention relates to a barrel intended, in particular for transporting liquid, viscous or pulverulent materials, as well as to a process for the manufacture of this barrel. According to the invention, the barrel is particularly suitable for hot filling, a method which is increasingly used in the packaging sector; the barrel according to the invention also meets standards of increased severity in terms of safety, environmental protection and size.

The barrel according to the invention is used in all cases where increased resistance to mechanical stress is required, and more particularly when the barrel is brought to undergo an internal depression.

With new production methods, the bulk packaging and transport sectors are placing increasingly stringent quality requirements on barrel manufacturers.

Thus, a practice which has become common, is hot filling, either to accelerate the rates and cut the loss of time, or to obtain sufficient fluidity of a viscous product to be packaged, such as oil. The barrel being hermetically closed, there occurs inside, during the cooling of its contents, a depression tending to crush it on itself.

However, most of the current barrels, calculated to support rather an internal pressure, resist the depression very poorly, which generates abnormal stresses on their walls.

To the effect of depression, are added the effects due to the superposition for storage, which causes instability and even the collapse of stacks of drums in warehouses.

Another weak point of the barrel is its bottom. When transporting over long distances by rail or road, the vibrations generated by the vehicle cause stresses on the bottom in the vertical (axial) direction due to the movements of the load. This results in risks of fracture at the periphery of the bottom.

To remedy this, it is obviously possible to increase the thickness of the sheets used, but this increases the cost price all the more and there is a risk of losing market shares.

From an environmental point of view, traditional barrels, the top of which is curved outwards, have the drawback of not being able to empty completely when placed vertically upside down "open bungs". In this case, there may remain in the convex part a large quantity of liquid possibly dangerous for man and / or for the environment. This liquid, whatever it is, will be left in the barrel and taken to an undetermined destination such as a garbage dump, scrap metal collector, etc., where its presence can cause irreparable damage.

The barrel manufacturer is limited in its research by the need to respect dimensions and standardized capacities; the drums must in particular have a maximum overall diameter compatible with the width of maritime containers standardized by ISO so that a whole number of drums per row can be placed in the width of such a container.

Several known solutions make it possible to reinforce the rigidity of the barrels. Application DE-A-2 738 946 describes a method of forming by rolling outward moldings and rods on the shell of a barrel. The moldings reinforce the barrels thus formed in the radial direction. However, there remain on the side wall of the barrels, cylindrical sections which poorly support a depressurization of these barrels.

Document DE-C-611 440 describes a method of manufacturing metal drums from a cylindrical blank threaded on an expansion mandrel; the metal of the blank is shaped without work hardening, the gain in diameter being taken up over the length of the blank. The bulging shape of the barrel thus formed causes a significant loss of space. This document serves as a preamble to claim 13.

In patent FR-1 349 042, a barrel is described, the shell of which is integrally molded and which therefore has increased resistance to radial stresses. However, users of barrels according to FR-1 349 042 pose an identification problem, since these barrels are devoid of any smooth lateral surface allowing the affixing of useful information on the nature of the content, its origin, etc.

Such a barrel also has less good rigidity in the axial direction.

The patent FR-A-15 68019 which corresponds to the preamble of claim 1, describes a barrel whose cylindrical body has two sets of moldings and two ends in the trunk of a cylinder. The barrel described in FR-A-1568019 is not designed to withstand internal depression; it has a retractable conical cover.

The object of the invention is to make available to users a barrel resistant to internal depression, without appreciable increase in manufacturing costs.

The object of the invention is also the placing on the market of drums suitable for hot filling and supporting the constraints imposed by high production rates and the vertical constraints due to stacking.

Another object of the invention is to preserve a smooth range (called "decoration range") without altering the resistance of the barrel.

Another object of the invention is also to be able to produce in particular a 216 liter barrel suitable for ISO transport containers, and which can be aligned, in particular in rows of four, over the width of a container, according to a square mesh and without wasting space.

The subject of the invention is a barrel, for the transport of liquids and pulverulent materials according to the preamble of claim 1, comprising annular sections being in the form of plump barrels, said annular sections and rods being made of steel hardened by expanding their circumference so that the drum offers increased resistance to internal depression.

One and even two ends in the trunk of the cylinder of the ferrule are advantageously made of cold-worked steel by expansion of their circumference.

In a preferred form, the barrel cover is a bung cover crimped to the ferrule; in another preferred form, the cover is a full opening cover held in place by a ring.

In an advantageous embodiment, the internal diameter of the cover is larger than the external diameter of the bottom, so that identical drums can be stacked on top of each other with embedding.

Preferably, the bottom of the barrel is crimped to the ferrule.

Preferably, also the bottom comprises a circular central part which is connected to an interlocking ring attached to the shell by a frustoconical crown, a circular groove being formed at the periphery of this crown, the circular central part extending substantially in the same plane as the end of the crimping of the ferrule.

The barrel advantageously has three sections and two rods; it comprises, according to a preferred embodiment, a cover which has a conformation favoring the complete flow of the contents when the barrel is turned upside down, cover down.

According to an advantageous embodiment, the shell of the barrel has a side strip capable of receiving a decorative coating.

According to another advantageous form, the rods have a diameter smaller or equal to that of the bulged part of the barrels.

The invention also relates to a process for the manufacture of a metal barrel according to the preamble of claim 13.

In this process, the metal of the ferrule, in the distended parts, is hardened and formed so that the whole of the ferrule is made up of sections in the form of bell-shaped barrels, the successive barrels being connected to each other via a rod pushed outwards, the largest diameter of which is less than or equal to the largest diameter of the barrels, the lower and upper parts of the shell each consisting of a cylinder trunk;
the cover and the bottom are secured to the ends of the ferrule.

According to a preferred embodiment, one proceeds to the cold expansion of one of the ends in the trunk of the cylinder of the ferrule, which is thus also made of cold-worked steel.

According to another embodiment, one proceeds to the cold expansion of the two ends in the trunk of the cylinder, so that they are both made of work hardened steel.

• insertion dans l'ébauche cylindrique d'un mandrin à expansion comportant des segments aptes à se déplacer radialement vers l'extérieur;
• déplacement radial des segments du mandrin de façon à obtenir un étirage de l'ébauche jusqu'à ce qu'elle ait atteint la forme désirée.

According to an advantageous embodiment of the method according to the invention, the expansion of the shell is carried out as follows:

• insertion into the cylindrical blank of an expansion mandrel comprising segments capable of moving radially outward;
• radial displacement of the mandrel segments so as to obtain a stretching of the blank until it has reached the desired shape.

One can cite in particular, among the advantages of the invention, the fact that starting from a reduced initial diameter, one can leave the border intended for crimping, set back with respect to the end of the ferrule, from where a limitation of the risks of collisions on this sensitive part of the barrel.

Another advantage is that the shaping method is quick.

Another advantage is that, since the distortion of the metal is relatively limited in the decoration range, it is possible to pre-print the strip metal, the final pattern being hardly affected by the shaping of the ferrule, or even to a decoration. with the stencil after forming, the stencil being able, by its flexibility, to marry the slight curvature of the metal.

Another advantage is that the barrel is self-supporting, devoid of prominent bearing rods sensitive to knocks.

• la Fig. 1 est une vue schématique en perspective d'un fût suivant l'invention;
• la Fig. 2 est une vue partielle en coupe, suivant le plan II-II, de la paroi latérale d'un fût suivant la Fig. 1;
• la Fig. 3 est une vue partielle en coupe, suivant le plan III-III, de l'angle inférieur du fût de la Fig. 1, et
• la Fig. 4 est une vue schématique d'un fût sectionné par un plan axial.

Other features and advantages of the invention will emerge from the description below of a particular embodiment of the invention given by way of example, reference being made to the appended drawings, in which:

• Fig. 1 is a schematic perspective view of a barrel according to the invention;
• Fig. 2 is a partial sectional view, along the plane II-II, of the side wall of a barrel according to FIG. 1;
• Fig. 3 is a partial sectional view, along the plane III-III, of the lower angle of the barrel of FIG. 1, and
• Fig. 4 is a schematic view of a barrel sectioned by an axial plane.

Fig. 1 schematically shows a barrel according to the invention, as a whole. The shell 1 of the barrel is formed of three sections, each of these sections 2 being separated from the adjacent section 2 by a rod 3. These rods 3 do not exceed a plane tangent to the wall and therefore serve essentially as stiffeners and not as rolling rods.

Each of the sections 2 is barrel-shaped. This barrel shape allows them to take up, without significant deformation, both the axial and radial stresses. Particularly sought-after advantage, this shape takes up both the radial stresses due, for example, to the overpressure as well as those caused by the depression of the barrel. The barrel, as a whole, has no prominent part and allows, for example, to produce barrels of 216 liters while respecting a maximum lateral dimensions of 585 mm; one can place four drums of 216 liters to ISO standards thus conformed side by side over the width of a standard ISO maritime container, which results in a substantial space saving compared to other drums of conventional manufacture.

Fig. 2 schematically shows a sectional view of a side wall segment.

The line in dotted lines 4 indicates the initial position of the wall of the blank, before it is shaped by expansion. As shown in Fig. 2, the side wall in its central part does not intersect at any point with the line in the axis 4; the wall of the blank has therefore been stretched at all points from the part shown here, so that the ferrule 1 is formed over almost its entire length, after its shaping, of cold-worked metal, more resistant and more elastic than the starting metal. This mechanical treatment contributes to reinforcing the advantage already conferred by the "barrel" shape of each section 2. The barrel shape shown in FIG. 2 is accentuated for the purposes of good understanding. Indeed, in practice, the difference in length of the radius of a barrel, between its central part (the widest) and its terminal parts, may not exceed 2% (or about 5 mm), which is barely detectable at the eye. The more swollen central part 5 is extended on both sides by a connection curve 6 and is connected to a rod 3 which forms a transition with the adjacent section and stiffens the barrel in the radial direction.

The barrels 5 of the two sections 2 arranged in on either side of the central section 2 have a substantially identical shape to the barrels 5 of the central section 2, these barrels 5 are connected by a connection curve 6 to the rod 3, on the one hand, and at the end cylindrical of the ferrule, on the other hand.

Due to the double curvature of the barrel shape 5, each section 2, and even the central section 2 which is normally the most stressed, can optimally resist vertical, radial mechanical stresses as well as over- or under pressure.

The increase in the diameter of the blank goes hand in hand with a reduction in the thickness of the metal used. This reduction in thickness is largely offset by the advantageous mechanical effect due to the work hardening of the metal and the shape of the shell.

As can be seen in Fig. 3, the barrel shape of a section 2 is connected, at the lower end of the barrel, to a part in the trunk of a cylinder 7 of diameter which may be equal to or slightly greater than that of the initial blank. The diameter of this part in the trunk of a cylinder 7 remains, however, several sheet thicknesses smaller than the maximum diameter of the barrels, so that if the ferrule 1 is joined to the bottom 8 by crimping, the outside diameter of the crimping bead 9 remains below or equal to the maximum diameter of the barrel as a whole.

An advantage of this arrangement is that the crimping bead 9 will be protected from impacts during handling.

As mentioned above, the angle 10 formed by the bottom 8 and its rim is, in a manner known to those skilled in the art, a weak point, which undergoes significant fatigue due to the vibrations of the bottom 8 during transport. This effect is greatly attenuated in the barrel according to the invention by the mounting of a so-called "anti-vibration" bottom which has a flexible peripheral groove 11, which attenuates vibrations, and by the presence of a conical crown 12 by which the bottom 8 is brought back in the same plane 13 as the crimping bead 9, so that, when the barrel is filled and arranged vertically, it effectively rests on its bottom 8.

The area of the angle 10 is therefore practically no longer affected by the tremors due to transport.

The way of making barrels by expansion applies equally to bung barrels, as shown in FIG. 1, only to fully open drums, as shown diagrammatically in FIG. 4.

To make an expanded barrel according to the invention, one starts with a blank formed from a metal cylinder whose diameter is slightly smaller than the nominal diameter of the barrel.

A mandrel is inserted into this blank, the segments of which can be moved radially outward, causing both the shaping and the drawing of the metal of the blank.

While adjusting to the dimensions of the ferrule, the metal is hardened, which improves its mechanical properties.

Depending on the characteristics of the barrel, it is not necessary to stretch the blank over its entire length. Some parts, like the ends or one end, can be left at their original diameter.

The expansion mandrel makes it possible to give the shell, in a single operation, a complex shape. According to the present invention, the different sections are given a barrel shape, which gives the barrel excellent mechanical qualities. These combine with the enhanced qualities of the ferrule steel to give a high quality barrel.

Fig. 4 illustrates the dimensional relationships between the different parts of the barrel 1. The ends have been left at a diameter R1, R2 close to that of the blank and are therefore practically not hardened. If we want the barrels to stack with interlocking, we choose R3 (outside diameter at the base) smaller or equal to R2 (inside diameter of the cover 14).

Furthermore, R5 (maximum radius of the rods) and R6 (maximum radius of the barrels) are chosen to be substantially equal, so that the barrel does not have projecting joints.

Depending on the constraints of use or handling, it is however possible to easily and without departing from the scope of the invention a barrel where R5 is larger than R6 or even the reverse.

It is obvious that the shape of the barrel shown here is in no way limiting and that, depending on the requirements of solidity, it may have a number of sections 2 more or less high, rods 3 of various shapes and more or less salient.

Finally, the 216 liter barrel described here as an embodiment, is of course only an example, and the method of embodiment according to the invention also applies to containers of all sizes intended for transport.

Claims (16)

1. Barrel for transporting liquids and pulverulent substances, comprising a lid (14), a bottom (8) and a ring wall (1), the ring wall (1) comprising annular sections (2) separated by rings (3) and two cylindrical ends (7), characterised in that : the said sections (2) are in the shape of bulging casks, the said sections (2) and the said rings (3) being made of steel work-hardened by expansion of their circumference, in such a way that the barrel offers an increased resistance to an internal reduced pressure.
2. Barrel according to Claim 1, characterised in that one of the cylindrical ends (7) of the ring wall (1) is also made of steel work-hardened by expansion of its circumference.
3. Barrel according to Claim 1, characterised in that the two cylindrical ends (7) of the ring wall (1) are made of steel work-hardened by expansion of its circumference.
4. Barrel according to any one of the preceding claims, characterised in that the lid (14) is a lid with a stopper and in that it is crimped to the ring wall (1).
5. Barrel according to any one of the preceding claims, characterised in that the lid (14) is a lid which can open totally and which is held in place by a hoop.
6. Barrel according to Claim 5, characterised in that the internal diameter of the lid (14) is greater than the external diameter of the bottom (8) so that identical barrels can be stacked on top of each other with interfitting.
7. Barrel according to any one of the preceding claims, characterised in that the bottom (8) is crimped to the ring wall (1).
8. Barrel according to Claim 7, characterised in that the bottom comprises a circular central part (8) which is connected to a fitting hoop located next to the ring wall (1) by means of a frustoconical crown (12), a circular groove (11) being formed at the periphery of this crown (12), the circular central part (8) extending substantially in the same plane as the crimping end (9) of the ring wall.
9. Barrel according to any one of the preceding claims, characterised in that it comprises three sections (2) and two rings (3).
10. Barrel according to Claim 4, characterised in that the lid (14) has a configuration which helps the contents to flow out completely when the barrel is turned upside-down, with the lid (14) facing downwards.
11. Barrel according to any one of the preceding claims, characterised in that the ring wall (1) comprises a lateral band which is capable of receiving a decorative coating.
12. Barrel according to any one of the preceding claims, characterised in that the rings (3) have a diameter which is less than or equal to that of the bulged part (5) of the casks.
13. Method for producing a metal barrel comprising a ring wall (1), as well as a lid (14) and a bottom (8) which are fixed, respectively, to the upper and lower end of the ring wall (1), in which

    - a cylindrical preform is produced, the diameter of which is less than or equal to the diameter of the ring wall of the finished barrel, in its most restricted part;

    - the cold expansion of this preform is carried out on an expansion device, characterised in that : the metal of the ring wall is work-hardened in the slack parts and formed in such a way that the whole ring wall is made up of sections (2) in the shape of bulging casks (5), the successive casks (5) being connected together by means of a ring (3) which is pushed outwards, but whose largest diameter is less than or equal to the largest diameter of the casks (5), the ends of the ring wall each consisting of a cylindrical section having a diameter which is greater than or equal to that of the preform;

    - the lid and the bottom are secured to the ends of the ring wall.
14. Method according to Claim 13, characterised in that the cold expansion of one of the cylindrical ends (7) of the ring wall (1) is carried out, in such a way that it is made of work-hardened steel.
15. Method according to Claim 13, characterised in that the cold expansion of the two cylindrical ends (7) of the ring wall (1) is carried out, in such a way that they are also made of work-hardened steel.
16. Method according to any one of Claims 13 to 15, characterised in that the expansion of the ring wall (1) includes the following operations :

    - insertion into the cylindrical preform of an expansion chuck comprising segments which are capable of moving radially outwards :

    - radial displacement of the segments of the chuck, so as to bring about the stretch-forming of the preform until this preform has reached the desired shape.

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