Patent Description:
It is known that spires of welding wire (coils), from <NUM> to <NUM>, are packaged and transported in cardboard (kraft) drums, see e.g. <CIT> and <CIT>. The drums are cylindrical or parallelepipeds and closed by a lid.

The big problem with these drums is the transport and storage in the warehouse. Given their low weight-to-volume ratio, transport costs are very high and the storage complicated. Furthermore, the drums are not very resistant mechanically, and therefore hardly reusable, they cannot tolerate water and humidity, and are not airtight.

<CIT> discloses a drum for containing a coil of welding wire on which the preamble of claim <NUM> is based.

The main object of the invention is to make a drum that mitigates or completely eliminates the above drawbacks.

A drum is then proposed for containing a coil of welding wire, comprising.

Thanks to the tapered or truncated cone or truncated pyramid shape various containers can be stack one on top of the other by inserting the bottom of one into the cavity of another. Therefore the transport volume is utilized much better.

A possible problem of a tapered drum is the instability of the coil contained in it and the unwinding of the wire. When the wire unwinds inside a tapered container it may happen some spires get stuck or twisted together, compromising the unwinding of the wire. An optimal unwinding of a coil should envisage that the internal diameter of the container remains constant. By a geometric factor, the residual space between the coil and the internal walls of the container, and therefore the internal diameter of the container in which the wire is wound, decreases from the top to the base. To solve this problem, the drum comprises a filling element shaped to extend into the space between the internal surface of the container and the lateral surface of an imaginary cylinder having a base substantially equal to the (greater) one of the container (or of said truncated cone or pyramid). In this way the coil "sees" a cylindrical drum.

The filling element may be rigid (i.e. capable of maintaining a constant shape) or flexible, to transport it folded or unfolded.

The filler element may completely fill said space, or partially to save material and make it lighter.

The filling element may have various embodiments.

The filling element in a variant comprises a cylindrical surface from which projecting portions, configured to occupy the distance between the inner surface of the container and the lateral surface of the imaginary cylinder, radially extend, wherein the maximum projection of the protruding portions (i.e. the radial length between a base of the protruding portion on the cylindrical surface and the point of the portion farthest away from the cylindrical surface) decreases - e.g. linearly - along the axis of the cylindrical surface.

The protruding portions are e.g. configured as pins, fingers, wings, bubbles, points, curls, spirals, or any other volume.

It is very convenient to be able to produce the filling element in an economical and fast way.

A preferred embodiment then envisages that the filling element comprises or consists of a (e.g. plastic) sheet having corrugations or said protruding portions spread over a surface, so that by folding the sheet to form a cylinder said cylindrical surface is obtained from which said protruding portions radially extend.

In particular, in the sheet the corrugations or said protruding portions comprise or are constituted of folds of the sheet. Preferably the folds of the sheet form a plurality of raised (e.g. fretted) ribs all extending parallel to each other from one edge of the sheet to an opposite edge all having height linearly decreasing in the same direction.

In the sheet folded like a cylinder, the ribs become a three-dimensional circular array to occupy said space.

Preferably, the plurality of ribs is made on a plastic sheet by means of thermoforming, which allows high production volumes and low cost.

The filling element in another variant comprises a wedge-shaped and/or tapered element placed inside the container, wherein the filling element has two ends and one end has smaller cross-section than the other end. The filling element is placed inside the container so that its smaller cross-section end is the one closest to the base of the container.

In particular, the drum may comprise a plurality of wedge-shaped and/or tapered filling elements as defined above, preferably arranged with polar symmetry around the center or axis of the container.

To stabilize a or each filling element inside the container, in particular the wedge-shaped and/or tapered one, preferably the drum and/or a or each filling element comprises fastening means or fastening elements for fixing the filling element to the container.

In particular, the means or elements for fastening to the container comprise a part on the filling element and a part on the internal surface of the container, the two parts being able to be fixed and/or fitted on each other through shape- or joint-coupling or interposition.

In a preferred embodiment, the fastening means or elements comprise an element, e.g. a hook or a hanger or a pin, which is protruding from the filling element and configured to cooperate by interlocking with a seat, e.g. a seat complementary to the protruding element, present on the inner surface of the container. The position of the protruding element and that of the seat may be swapped.

In another preferred embodiment, the fastening means or elements comprise a cavity obtained in the base of the container, the cavity being complementary to the end of the filling element which has smaller cross-section, the latter end being inserted into the cavity. Or the fastening means or elements comprise a cavity obtained in one (e.g. lower) end of the filling element and the inner surface of the container comprises a projection complementary to the cavity, so that the projection can be inserted into the cavity.

In another preferred embodiment, the fastening means or elements comprise adhesives or Velcro®.

The advantages of the invention will be further clarified by preferred embodiments described below with reference to the attached drawings, in which:.

In the figures, like references indicate identical or similar parts, and described as in use.

To avoid crowding the drawings, some elements are not indicated repeatedly.

A drum MC serves to contain a coil of welding wire (not shown).

The drum MC comprises a container <NUM> having a bottom <NUM> and side walls <NUM> for delimit a cavity <NUM> to house the coil. The cavity <NUM> is closable by a lid <NUM>.

The container <NUM> is a shell in the shape of a truncated cone, with Y axis, which in use is tapered downwards. Hence the ease of being able to stack one drum MC inside another.

Preferably the container <NUM> is made of plastic material, and at the center of the bottom <NUM> it integrally comprises a raised ring or disc <NUM>, useful for centering the spires or coil and/or for abutting against an optional cylinder <NUM> placed in the center of the container <NUM> to center the coil. The ring or disc <NUM> has a preferred height of <NUM> to <NUM>, preferably about <NUM>.

The bottom of the container <NUM> comprises (<FIG>) a diametrical groove <NUM> which runs outside the base of the truncated cone, useful for receiving a lifting strap <NUM> for the drum MC.

Preferably the container <NUM> has an edge <NUM> (<FIG>) which delimits the opening closable by the lid <NUM>, and the edge <NUM> comprises an eyelet <NUM> for the passage of the belt <NUM>.

In particular, in the eyelet <NUM> there is a, e.g. flexible, tooth <NUM> to clamp the strap <NUM> on the edge <NUM> and keep it in place.

Preferably, the lid <NUM> comprises (<FIG>) an eyelet <NUM> for the passage of the belt <NUM>, so as to exploit the belt <NUM> also to keep the lid <NUM> fixed on the container <NUM>.

To compensate for the truncated-cone shape of the drum and bring the interior thereof back to a cylindrical surface, the drum MC preferably comprises a filling element <NUM> (see <FIG>, <FIG>). The filling element <NUM> ensures that the unwinding of the coil wire takes place with uniformity and is not affected by the fact that the distance between the coil and the inner surface of the container <NUM> varies with height.

The filling element <NUM> is shaped to extend into the space S between the inner surface of the container <NUM> and the lateral surface of an imaginary cylinder <NUM> having base substantially equal to the (greater) one of said truncated cone, see <FIG>.

The filling element <NUM> preferably comprises a cylindrical surface <NUM> from which projecting portions <NUM>, configured to occupy the distance between the inner surface of the container <NUM> and the lateral surface of the imaginary cylinder <NUM>, extend radially (orthogonally to Y), see <FIG>.

The maximum projection of the projecting portions <NUM> decreases linearly along the Y axis of the cylindrical surface <NUM>.

The projecting portions <NUM> may have different embodiments, e.g. configured as rigid pins or fingers as in <FIG>.

Another preferred embodiment envisages that the filling element <NUM>, see <FIG>, comprises or consists of a (e.g. plastic) sheet <NUM> folded into a cylinder such as shown in <FIG>.

Corrugations <NUM> are formed on the sheet <NUM> which function as the aforesaid projecting portions <NUM>. Thus folding the sheet <NUM> to form a cylinder gives a cylinder from which the corrugations <NUM> extend radially, e.g. in all directions.

In particular, the corrugations <NUM> consist of folds of the sheet <NUM> which form a plurality of raised ribs (e.g. fretted ribs) which all extend parallel to each other from a margin <NUM> of sheet <NUM> to an opposite margin <NUM>.

Each rib has a height that decreases linearly along Y, to adapt to the tapering of the space S towards the bottom <NUM>.

<FIG> shows in an exaggerated way the variation in projection for a rib <NUM>.

Before starting the unwinding of a coil, the cylinder-folded sheet <NUM> is inserted inside the container <NUM>. The coiled wire is fenced by the sheet <NUM>, which does not bend and stays in position thanks to the reaction of the corrugations <NUM> against the inner wall of the container <NUM>.

Another variant of filling element <NUM> is shown in conjunction with a drum MC2, see <FIG>. The drum MC2 comprises a container <NUM> having a bottom <NUM> and side walls <NUM> to delimit a cavity <NUM> for housing the coil. The cavity <NUM> is closable by a lid <NUM>.

The container <NUM> is a tapered-shaped shell, e.g. as a truncated pyramid or cone, with Y axis, which tapers - in use - downwards.

To compensate for the tapered shape of the container <NUM> and bring the inside thereof back to a cylindrical surface, the drum MC2 comprises one or more filling elements <NUM> (see <FIG>), with the same effect as element <NUM>.

The filling element <NUM> is shaped like a wedge and so as to extend into the space between the inner surface of the container <NUM> and the side surface of an imaginary cylinder <NUM> having a base substantially equal to the (greater) one of the container <NUM>. The filling element <NUM> has a shorter base <NUM> and a longer base <NUM>, and is preferably a hollow shell, to limit the total weight of the drum.

Each illustrated filling element <NUM>, <NUM><NUM> preferably comprises a protruding hook <NUM> that can be inserted into a pocket or edge <NUM> obtained on the internal surface of the respective container <NUM>, <NUM>, see e.g. <FIG>. In this way the filling element <NUM>, <NUM>, <NUM> is stabilized inside the container <NUM>, <NUM>, preventing it from falling or moving.

Preferably to stabilize the filling element <NUM>, <NUM>, <NUM> inside the container, the inner surface of the base of the respective container <NUM>, <NUM> comprises a cavity <NUM> complementary to the smaller base <NUM> of the filling element <NUM>, <NUM>, <NUM>. - see <FIG> - the shorter base <NUM> is placed inside a cavity <NUM> so that this joint makes one end of the filling element <NUM> immovable.

In the illustrated example, various filling elements <NUM> are arranged inside the container <NUM> with polar symmetry, e.g. according to the vertices of a regular polygon, such as a square or a triangle.

Claim 1:
Drum (MC1; MC2) for containing a coil of welding wire, comprising:
• a container (<NUM>; <NUM>) having a bottom (<NUM>; <NUM>) and side walls (<NUM>; <NUM>) for delimiting a cavity (<NUM>; <NUM>) in which the coil can be housed, and
• a lid (<NUM>; <NUM>) to close the container (<NUM>; <NUM>),
wherein the container (<NUM>; <NUM>) has a tapered shape and the smaller base of the container (<NUM>; <NUM>) corresponds to the bottom (<NUM>; <NUM>) of the container (<NUM>; <NUM>),
the container (<NUM>; <NUM>) having the shape of a truncated cone or truncated pyramid,
characterized by comprising
a filling element (<NUM>; <NUM>) shaped to extend into the space (S) comprised between the inner surface of the container (<NUM>; <NUM>) and the lateral surface of an imaginary cylinder having a base substantially equal to that of the container (<NUM>; <NUM>).