Patent Description:
This invention also relates to pieces of a multilayer, cylindrical tubular rod suitable for making substantially cylindrical smokers' articles.

As described in patent application <CIT> machines are known in the prior art which are used to make smokers' articles where cylindrical components of smokers' products of any kind are wrapped in a multilayer web comprising strips suitable for imparting desired properties. The strips are made, for example, of a metallic material or a plastic material. Thus, the machine described in <CIT> is suitable for directly making the pieces of smokers' articles by wrapping the multilayer web around the cylindrical components.

Document <CIT> discloses a tube maker, particularly for making tubes for papirosi, has a mandrel around which the tube is formed and which has air passages for supplying an air bearing for the tube. Document <CIT> provides a method of making filter plugs for cigarettes including the steps of feeding simultaneously to a garniture filter material in the form of a sliver or a rod, a strip of relatively stout paper having a width such that it is formed in the garniture into an inner tube surrounding the sliver or rod and having a longitudinal butt joint, and a strip of thinner paper having a width such that it is formed in the garniture into an outer tube surrounding the butt-jointed tube and having a longitudinal lapped joint, an adhesive being applied over the whole or the greater part of the external surface of the butt-jointed inner tube or over the whole or the greater part of the internal surface of the lap-jointed outer tube or over the whole or the greater part of both said surfaces. Document <CIT> provides a method of forming paper or like tubes and comprising feeding a strip of material lengthwise to provide a cover member, folding a further strip of material into a tube with its longitudinal edges juxtaposed without overlapping about the cover member whilst both strips of material are being moved lengthwise, applying adhesive to that surface of one strip which is to engage with -the other strip and pressing the cover member into engagement with the inside of the tube formed from said second strip to complete the butt joint.

At present, therefore, no machine or method is available to provide pieces of a multilayer, cylindrical tubular rod suitable to be subsequently filled axially with the cylindrical components necessary to make the smokers' article. In effect, in this case, it would be necessary to have pieces of a multilayer, cylindrical tubular rod which comply with stringent dimensional and shape tolerances, with reference in particular to the internal diameter which has to receive the aforementioned components.

At present, prior art machines and methods are not capable of complying with specified tolerances because they are subject to errors in the positioning and/or alignment of individual layers of the multilayer web and to phase displacements between the process stations due, for example, to tension variations in the feeding of the continuous webs.

This invention therefore has for an aim to provide a method and a machine for making pieces of a multilayer, cylindrical tubular rod to overcome the disadvantages described above with reference to the prior art.

More specifically, the aim of this invention is to provide a method and a machine for making pieces of a multilayer, cylindrical tubular rod and capable of providing pieces of rod which comply with stringent dimensional and shape tolerances, with reference in particular to the internal diameter.

Another aim of this invention is to provide a method and a machine for making pieces of a multilayer, cylindrical tubular rod and capable of adapting to different types of products to be made and of making a reliable product which, in particular, guarantees complete closure along the circumferential direction and correct circumferential and longitudinal positioning of the different layers.

A further aim of this invention is to provide a piece of a multilayer, cylindrical tubular rod which is suitable for making substantially cylindrical smokers' articles and which allows the cylindrical components to be easily inserted at a later stage, guaranteeing the seal between the piece and the component for example in such a way that air can pass through the component.

These aims are achieved by a method and a machine for making pieces of a multilayer, cylindrical tubular rod having the features set out in one or more of the appended claims.

These aims are also achieved by a piece of a multilayer, cylindrical tubular rod suitable for making substantially cylindrical smokers' articles and having the features set out in one or more of the appended claims. Advantageously, carrying out the steps of the method in a single machine makes it possible to avoid phase displacements along the feed direction. Also, by wrapping the continuous, multilayer web around the feed direction to form a multilayer, cylindrical tubular rod and making at least one end-to-end splice, it is possible to reduce the shape and size irregularities of the piece, thereby complying with specified shape and size tolerances.

The piece of rod obtained comprises a first layer comprising a first splice, a second continuous layer comprising a second splice and a third continuous layer comprising a third splice,
where at least one between the first and the second splice is made as an end-to-end splice.

Preferably, a first material is used which comprises one or more of the following: a metallic material, a plastic material, a paper material.

Preferably, a first, a second and a third layer are used, where the second and third layers have the same thickness. For example, the layers with the same thickness are obtained by feeding a single continuous web and dividing it longitudinally into two continuous web portions defining a second continuous web and a third continuous web. Alternatively, the second layer and the third layer have different thicknesses.

Preferably, both the first splice and the second splice are end-to-end splices. The third splice may be an end-to-end splice, offset relative to the first or the second splice, or it may be an overlapping splice, preferably offset relative to the first or the second splice.

Further features and advantages of the invention are more apparent from the following exemplary and therefore non-limiting description of a preferred and hence non-exclusive embodiment of a piece of a multilayer, cylindrical tubular rod suitable for making substantially cylindrical smokers' articles, and a method and machine for making pieces of a multilayer, cylindrical tubular rod suitable for making substantially cylindrical smokers' articles.

The invention is described below with reference to the accompanying drawings, which illustrate a non-limiting embodiment of it and in which:.

With reference to the accompanying drawings, the numeral <NUM> denotes a multilayer, cylindrical tubular rod from which pieces suitable for making substantially cylindrical smokers' articles are obtained.

The rod <NUM>, and thus a piece of it not illustrated, comprises a first layer <NUM> of a first material. The first layer <NUM> is spliced longitudinally to form a first splice <NUM> of respective lateral edges <NUM> of the first layer <NUM>.

The rod <NUM>, and thus a piece of it not illustrated, comprises a second layer <NUM> of a second material. The second layer <NUM> is spliced longitudinally to form a second splice <NUM> of respective lateral edges <NUM> of the second layer <NUM>.

The first layer <NUM> occupies a radially inner position relative to the second layer <NUM> in both the piece and the rod <NUM>.

The second layer <NUM> is continuous along a main direction of extension "X" of the rod <NUM>, coinciding with the feed direction of the rod during production of the pieces.

At least one between the first splice <NUM> and the second splice <NUM> is made as an end-to-end splice, that is, a splice made without overlapping the two respective lateral edges.

The first material and the second material are different. For example, the first material may be a metallic material and the second material may be a paper material.

<FIG> illustrate a rod <NUM> where the first layer <NUM> is also continuous along the main direction of extension "X" of the rod <NUM>. Further, both the first splice <NUM> and the second splice <NUM> are end-to-end splices and are offset from each other, that is, they are disposed at different angular positions around the direction "X". <FIG> illustrates a step in the production of the rod <NUM> from a continuous multilayer web "M" comprising the first layer <NUM> and the second layer <NUM>, both laid out flat. Also illustrated is an intermediate layer <NUM> of adhesive material interposed between the first layer <NUM> and the second layer <NUM>.

<FIG> illustrate a rod <NUM> comprising a third layer <NUM> occupying a radially outer position relative to the first layer <NUM> and second layer <NUM>. The third layer <NUM> is spliced longitudinally to form a third splice <NUM> of respective lateral edges <NUM> of the third layer <NUM>. Both the first splice <NUM> and the second splice <NUM> are end-to-end splices and preferably are disposed at the same angular position around the direction "X". The third splice <NUM> is an end-to-end splice and is offset relative to the first and second splices, that is, disposed at a different angular position around the direction "X".

Again with reference to <FIG>, the first layer <NUM> is discontinuous and comprises, along the feed direction, a sequence of strips <NUM> alternated with empty spaces <NUM>. In this case, complete closure of the rod <NUM> is guaranteed by the third layer <NUM> and the third splice <NUM> offset from the other splices.

<FIG> illustrates a step in the production of the rod <NUM> from a continuous multilayer web "M" comprising the first layer <NUM>, the second layer <NUM> and the third layer <NUM>, all laid out flat. Also illustrated is the intermediate layer <NUM> of adhesive material interposed between the first layer <NUM> and the second layer <NUM> and a further intermediate adhesive layer <NUM> interposed between the second layer <NUM> and the third layer <NUM>. The third layer is offset along a direction perpendicular to the direction "X" relative to the first and second layers, so as to offset the respective third splice <NUM> relative to the first splice <NUM> and second splice <NUM>.

The second layer <NUM> and the third layer <NUM> have the same thickness and are preferably obtained by dividing a single continuous web longitudinally, as described hereinafter.

<FIG> illustrate a rod <NUM> comprising the third layer <NUM> occupying a radially outer position relative to the first layer <NUM> and second layer <NUM>. The third layer <NUM> is spliced longitudinally to form the third splice <NUM> of respective lateral edges <NUM> of the third layer <NUM>. Unlike the rod of <FIG>, the second layer <NUM> and the third layer <NUM> have different thicknesses: in particular, the second layer <NUM> is smaller in thickness than the third layer <NUM>. In this case, the function of the second layer <NUM> is that of transporting the first layer <NUM>. Thanks to the reduced thickness, it is easier to wrap it around itself and it may be made in such a way as to better absorb the adhesive material of the intermediate layer <NUM>. The third layer <NUM> acts mainly as a supporting layer and gives the rod <NUM> and the related pieces the stiffness necessary to keep their shape.

Again with reference to <FIG>, the first layer <NUM> is discontinuous and comprises, along the feed direction, the sequence of strips <NUM> alternated with empty spaces <NUM>. In this case, complete closure of the rod <NUM> is guaranteed by the third layer <NUM> and the third splice <NUM> offset from the other splices. <FIG> is similar to <FIG>.

<FIG> illustrate a rod <NUM> comprising the third layer <NUM> occupying a radially outer position relative to the first layer <NUM> and second layer <NUM>. The third layer <NUM> is spliced longitudinally to form the third splice <NUM> of respective lateral edges <NUM> of the third layer <NUM>. Unlike the rod of <FIG>, the second layer <NUM> and the third layer <NUM> have different thicknesses: in particular, the second layer <NUM> is larger in thickness than the third layer <NUM>. In this case, the second layer <NUM> acts both as a layer for transporting the first layer <NUM> and as a supporting layer giving the rod <NUM> and the related pieces the stiffness necessary to keep their shape. The functions of the third layer <NUM> are mainly to improve aesthetic appearance and to help keep the second layer <NUM> closed.

<FIG> illustrate a rod <NUM> comprising the third layer <NUM> occupying a radially outer position relative to the first and second layers. The third layer <NUM> is spliced longitudinally to form the third splice <NUM> of respective lateral edges <NUM> of the third layer <NUM>. Unlike the rod of <FIG>, the third splice <NUM> is an overlapping splice and is preferably offset from the first splice <NUM> or the second splice <NUM>, that is, is disposed at a different angular position around the direction "X".

Again with reference to <FIG>, the first layer <NUM> is discontinuous and comprises, along the feed direction, a sequence of strips <NUM> alternated with empty spaces <NUM>. In this case, the complete closure of the rod <NUM> is guaranteed by the third layer <NUM> and the third splice <NUM> which is offset from the other splices and is an overlapping splice.

<FIG> illustrates a step in the production of the rod <NUM> from a continuous multilayer web "M" comprising the first layer <NUM>, the second layer <NUM> and the third layer <NUM>, all laid out flat. Also illustrated is the intermediate layer <NUM> of adhesive material interposed between the first layer <NUM> and the second layer <NUM> and the further intermediate adhesive layer <NUM> interposed between the second layer <NUM> and the third layer <NUM>. The third layer <NUM> is aligned at least at one of the lateral edges of the first layer <NUM> and second layer <NUM>.

<FIG> illustrate a rod <NUM> comprising the third layer <NUM> occupying a radially outer position relative to the first and second layers. The third layer <NUM> is spliced longitudinally to form the third splice <NUM> of respective lateral edges <NUM> of the third layer <NUM>. Unlike the rod of <FIG>, the first splice <NUM> is an overlapping splice, the second splice <NUM> is an end-to-end splice and the third splice <NUM> is an overlapping splice and is preferably offset from the first splice <NUM> or the second splice <NUM>. The second layer <NUM> and the third layer <NUM> have different thicknesses: in particular, the second layer <NUM> is larger in thickness than the third layer <NUM>.

Again with reference to <FIG>, the first layer <NUM> is discontinuous and comprises, along the feed direction, a sequence of strips <NUM> alternated with empty spaces <NUM>. In this case, complete closure of the rod <NUM> is guaranteed by the third layer <NUM> and the third splice <NUM> offset from the other splices. The continuity of the first layer <NUM> along a circumferential direction is guaranteed by the first splice <NUM>, which is an overlapping splice.

<FIG> illustrates a step in the production of the rod <NUM> from a continuous multilayer web "M" comprising the first layer <NUM> and the second layer <NUM>, which are laid out flat and which, when subsequently wrapped on themselves, form an intermediate rod <NUM>. Also illustrated is the intermediate layer <NUM> of adhesive material interposed between the first layer <NUM> and the second layer <NUM>. <FIG> illustrates a further step in the production of the rod <NUM> from the intermediate rod <NUM> and the third layer <NUM>. The third layer <NUM> will be wrapped around the intermediate rod <NUM> to form the rod <NUM>. Also shown is the further intermediate adhesive layer <NUM> interposed between the second layer <NUM> and the third layer <NUM>.

In all the examples illustrated and/or described above, the first material may comprise one or more of the following: a metallic material, a plastic material, a paper material.

<FIG> and <FIG> illustrate two possible embodiments of a machine <NUM> for making pieces of a multilayer, cylindrical tubular rod <NUM> suitable for making substantially cylindrical smokers' articles. More specifically, the machine <NUM> is adapted to make a piece of a rod <NUM> according to one or more of the examples illustrated and/or described above.

The machine <NUM> comprises first means <NUM> for feeding at least a first continuous web <NUM> of a first material suitable for making the first layer <NUM> of a continuous, multilayer web "M" and of the rod <NUM>.

The machine <NUM> comprises second means <NUM> for feeding a second continuous web <NUM> of the second material suitable for making a second continuous layer <NUM> of the continuous, multilayer web "M" and of the rod <NUM>. The first continuous web <NUM> and/or the second continuous web <NUM> are preferably provided on rolls "B" unwound by respective means <NUM>, <NUM> for feeding the continuous webs.

Located along the feed path of the second continuous web <NUM> there is a gluing device <NUM> configured to apply a layer of adhesive material on the second continuous web <NUM> to define the intermediate layer <NUM> of adhesive material of the rod <NUM>. The intermediate layer <NUM> is preferably continuous. The gluing device <NUM> may be embodied, for example by rollers, sprayers or in other ways.

Located along the feed path of the first continuous web <NUM> there may be a cutting device <NUM> configured to cut the first continuous web <NUM> into strips <NUM>. The cutting device <NUM> is provided when the first layer <NUM> is discontinuous, that is to say, when it comprises a sequence of strips <NUM> alternated with empty spaces <NUM>. The cutting device <NUM> may be a cutter of the impact or scissor type or it may be embodied in other ways.

The numeral <NUM> denotes means for forming the continuous, multilayer web "M" by superposing at least the first layer <NUM> and the second layer <NUM>. These means may, for example, comprise a bed 107a embodied by a conveyor <NUM> adapted to receive the second continuous web <NUM> defining the second layer <NUM> and the strips <NUM> of the first continuous web <NUM> defining the first, discontinuous layer <NUM> (alternatively, the conveyor receives the first continuous web <NUM> defining the first continuous layer <NUM>). The conveyor <NUM> is also adapted to feed the continuous, multilayer web "M" along the feed direction "X" and thus also embodies means for feeding the continuous, multilayer web "M" along the feed direction "X". Preferably, the conveyor <NUM> receives the second continuous web <NUM> with the intermediate layer <NUM> which is applied thereon and on which the strips <NUM> of the first continuous web <NUM> are placed by a drum <NUM> associated with the cutting device <NUM>.

Downstream of the drum <NUM>, therefore, the continuous, multilayer web "M" obtained is such that the first layer <NUM> in the rod <NUM> occupies a radially inner position relative to the second layer <NUM>.

Downstream of the conveyor <NUM>, means <NUM> are provided for forming the rod <NUM> around the feed direction "X" making the splices of the layers making up the rod itself;
The means <NUM> may comprise a forming beam 110a having a groove whose cross section is variable along the feed direction "X" in such a way as to wrap the continuous, multilayer web "M" around the feed direction "X" to make the rod <NUM>.

Downstream of the means <NUM> for forming the rod <NUM> there are means <NUM> for cutting the rod <NUM> into pieces.

Advantageously, the machine <NUM> is configured to dispose the lateral edges of at least one between the first layer <NUM> and the second layer <NUM> in such a way as to make at least one between the first splice <NUM> and the second splice <NUM> as an end-to-end splice.

As illustrated in <FIG> and <FIG>, third means <NUM> may be provided for feeding a third continuous web <NUM> of a third material suitable for making the third layer <NUM> of the rod <NUM>. The third continuous web <NUM>, hence the third layer <NUM>, is disposed in such a way as to occupy, in the rod <NUM>, a radially outer position relative to the first layer <NUM> and second layer <NUM>. Along the feed path of the third continuous web <NUM> there is a gluing device 105a configured to apply the further intermediate adhesive layer <NUM> interposed between the second layer <NUM> and the third layer <NUM>. The gluing device <NUM> may be embodied, for example by rollers, sprayers or in other ways.

In the example shown in <FIG>, the third means <NUM> feed the third web <NUM> downstream of the conveyor <NUM> and upstream of the means <NUM> to form the third layer <NUM>. Thus, the first layer <NUM>, the second layer <NUM> and the third layer <NUM> form the continuous, multilayer web "M" and are wrapped together on themselves along the forming beam 110a.

If necessary, the machine <NUM> may comprise two blades <NUM> located on opposite sides of the continuous, multilayer web "M" and configured to trim the edges thereof. In the case of <FIG>, the blades <NUM> are circular blades which use as their anvil element a flat surface <NUM> on which at least one active portion of the conveyor <NUM> slides. The blades are located downstream of the drum <NUM> and thus trim the continuous, multilayer web "M" comprising the first layer <NUM> and the second layer <NUM>.

If necessary, the machine <NUM> may comprise a forming device <NUM> configured to preform the continuous, multilayer web "M" before it is wrapped on itself to form the rod <NUM>. <FIG> illustrate a possible example of the forming device <NUM>, which can be used in any machine for forming a rod <NUM> and which comprises a moulded groove <NUM>, adapted to receive the continuous, multilayer web "M", and a forming element - for example a wheel <NUM> - which fits at least partly in the moulded groove <NUM> to make in the continuous, multilayer web a grooved shape extending along the middle of it in the feed direction "X". The forming device <NUM> may act on a continuous, multilayer web "M" comprising only the first layer <NUM> and the second layer <NUM> or, as illustrated in <FIG>, on a continuous, multilayer web "M" comprising the first layer <NUM>, the second layer <NUM> and the third layer <NUM>.

The machine <NUM> illustrated in <FIG> differs from the machine illustrated in <FIG> in that it comprises two forming beams. The first forming beam 110a is similar to the one illustrated in <FIG> and is configured to make the rod <NUM>. A further forming beam <NUM> is located at the conveyor <NUM> to wrap the continuous, multilayer web "M", comprising the first layer <NUM> and the second layer <NUM>, on itself to form the intermediate rod <NUM>. The third continuous web <NUM> is fed between the further forming beam <NUM> and the forming beam 110a to wrap the third continuous web <NUM> around the intermediate rod <NUM> to form the rod <NUM>.

In use, the machine <NUM> is adapted to function according to a method for making pieces of a multilayer, cylindrical tubular rod suitable for making substantially cylindrical smokers' articles.

The above mentioned method comprises a step a) of feeding at least a first continuous web <NUM> of a first material suitable for making a first layer <NUM> of a continuous, multilayer web "M". This step is carried out, for example, by the first feed means <NUM>.

The above mentioned method comprises a step b) of feeding a second continuous web <NUM> of a second material suitable for making a second continuous layer <NUM> of the continuous, multilayer web "M". This step is carried out, for example, by the second feed means <NUM>.

According to the invention, there is a step f) of feeding a third continuous web <NUM> of a third material suitable for making a third layer <NUM> of the rod <NUM>. The third layer <NUM> is disposed in such a way as to occupy, in the rod <NUM>, a radially outer position relative to the first layer <NUM> and second layer <NUM>.

The above mentioned method comprises a step c) of forming the continuous, multilayer web "M" by superposing at least the first layer <NUM> and the second layer <NUM>, where the first layer <NUM> is positioned in such a way as to occupy, in the rod <NUM>, a radially inner position relative to the second layer <NUM>, and feeding the continuous, multilayer web "M" along a feed direction "X". This step is carried out, for example, at the means <NUM> and at the conveyor <NUM>.

The above mentioned method comprises a step d) of wrapping the continuous, multilayer web "M" around the feed direction "X", making at least a first splice <NUM> of the lateral edges of the first layer <NUM> and a second splice <NUM> of the lateral edges of the second layer <NUM>, to form the rod <NUM>. This step may be carried out in the forming beam 110a to form a continuous, multilayer web "M" comprising the first layer <NUM>, the second layer <NUM> and possibly also the third layer <NUM>, or in the forming beam <NUM> to form a continuous, multilayer web "M" comprising the first layer <NUM> and the second layer <NUM>. In the latter case, the forming of the rod <NUM> may, if necessary, be completed by wrapping the third layer <NUM> around the intermediate rod <NUM>. The above mentioned method comprises a step e) of cutting the rod <NUM> into pieces.

Steps a) to e) are carried out in a single machine <NUM> to make a multilayer, cylindrical tubular rod <NUM>. Also, step d) is carried out by disposing the lateral edges of at least one between the first layer <NUM> and the second layer <NUM> in such a way as to make at least one between the first splice <NUM> and the second splice <NUM> as an end-to-end splice.

Preferably, there is a step of making strips <NUM> of the first continuous web <NUM> and making a first, discontinuous layer <NUM> along the feed direction "X" where the first, layer <NUM> comprises, along the feed direction, a sequence of strips <NUM> alternated with empty spaces <NUM>. This step is carried out, for example, by the cutting device <NUM>.

If necessary, there may be a step of feeding a single continuous web suitable for making the second layer <NUM> and the third layer <NUM> and a step of dividing the single continuous web longitudinally into two continuous web portions respectively defining the second continuous web <NUM> and the third continuous web <NUM>. In this case, the second continuous web <NUM> and the third continuous web <NUM> have the same thickness. Alternatively, the second continuous web <NUM> and the third continuous web <NUM> have different thicknesses.

As illustrated in <FIG>, step c) comprises first forming the continuous, multilayer web "M" by superposing the first layer <NUM> and the second layer <NUM> and then adding the third layer <NUM>. The continuous, multilayer web "M" thus obtained (that is to say, comprising the first layer <NUM>, the second layer <NUM> and the third layer <NUM>) is wrapped on itself around the feed direction "X" to form the rod <NUM>.

In a possible embodiment, step d) may be carried out by disposing the lateral edges of the first layer <NUM> in such a way as to make a first end-to-end splice <NUM> and disposing the lateral edges of the second layer <NUM> in such a way as to make a second end-to-end splice <NUM>.

In this case, step c) might comprise the step of offsetting the third layer <NUM> relative to at least one between the first and the second layer along a direction perpendicular to the feed direction "X" and step d) might be carried out by disposing the lateral edges of the third layer in such a way as to make a third end-to-end splice <NUM> (<FIG>). Alternatively, step d) might be carried out by disposing the lateral edges of the third layer <NUM> in such a way as to make the third splice an overlapping splice (<FIG>).

As illustrated in <FIG>, step c) comprises forming the continuous, multilayer web "M" by superposing the first layer <NUM> and the second layer <NUM>. Next, the continuous, multilayer web "M" is wrapped on itself to form an intermediate rod <NUM> and juxtaposed with the third continuous web <NUM>, that is, with the third layer <NUM>, to wrap the third continuous web <NUM> around the intermediate rod <NUM> to form the rod <NUM>. In other words. , there is a step g) of wrapping the third layer <NUM> around the intermediate rod <NUM> already formed by wrapping the first and second layers around themselves. Preferably, step d) may be carried out by disposing the lateral edges <NUM> of the first layer <NUM> in such a way as to make at least a first, overlapping splice <NUM> and disposing the lateral edges <NUM> of the second layer <NUM> in such a way as to make a second, end-to-end splice <NUM>. Preferably, step g) is carried out by disposing the lateral edges <NUM> of the third layer <NUM> in such a way as to make a third, overlapping splice <NUM> (<FIG>).

If necessary, the edges of the continuous, multilayer web "M" might be trimmed before the web is wrapped on itself to form a multilayer, cylindrical tubular rod. More specifically, the edges of the continuous, multilayer web "M" formed by the first layer <NUM> and second layer <NUM> might be trimmed.

If necessary, before the continuous, multilayer web "M" is wrapped on itself to form the rod <NUM>, it might be preformed by making in the continuous, multilayer web a grooved shape extending along the feed direction "X".

In an alternative not illustrated, the machine <NUM> is adapted to make rods <NUM> which comprise only the first layer <NUM> and the second layer <NUM> with a first and a second end-to-end splice. In this case, the first layer <NUM> is continuous along the feed direction "X" and the first layer <NUM> and second layer <NUM> are offset in a direction perpendicular to the feed direction "X".

Claim 1:
A method for making empty pieces of a multilayer, cylindrical tubular rod (<NUM>) suitable for making substantially cylindrical smokers' articles, comprising the steps of:
a) feeding at least a first continuous web (<NUM>) of a first material suitable for making a first layer (<NUM>) of a continuous, multilayer web (M);
b) feeding a second continuous web (<NUM>) of a second material suitable for making a second continuous layer (<NUM>) of the continuous, multilayer web (M);
c) forming the continuous, multilayer web (M) by superposing at least the first layer (<NUM>) and the second layer (<NUM>), wherein the first layer (<NUM>) is positioned in such a way as to occupy, in the rod (<NUM>), a radially inner position relative to the second layer (<NUM>), and feeding the continuous, multilayer web (M) along a feed direction (X);
d) wrapping the continuous, multilayer web (M) around the feed direction (X), making at least a first splice (<NUM>) of the lateral edges (<NUM>) of the first layer (<NUM>) and a second splice (<NUM>) of the lateral edges (<NUM>) of the second layer (<NUM>), to obtain an empty rod (<NUM>) having a round internal transverse cross section along the feed direction;
e) cutting the empty rod (<NUM>) into empty pieces;
the steps a)-e) being performed on a single machine (<NUM>) for making a multilayer, cylindrical tubular rod (<NUM>) wherein the step d) is accomplished by disposing the lateral edges (<NUM>, <NUM>) of at least one between the first and the second layer (<NUM>, <NUM>) in such a way as to make at least one between the first and the second splice (<NUM>, <NUM>) as an end-to-end splice;
characterized in that the method comprises a step f) of feeding a third continuous web (<NUM>) of a third material suitable for making a third layer (<NUM>) of the rod (<NUM>), wherein the third layer (<NUM>) is positioned in such a way as to occupy, in the rod (<NUM>), a radially outer position relative to the first and second layers (<NUM>, <NUM>).