UNIT FOR PROCESSING A CONTINUOUS WEB

Technical field

This invention relates to a unit for processing a continuous web and, more specifically, a rotary operating unit for performing processes on a continuous web.

Background art

Typically, in machines for the production of articles or packages involving processes performed on continuous webs, there are operating units or wheels or processing units or wheels which allow performing operations such as welding, for example, on the continuous web while the web is being fed.

In a prior art embodiment, these operating units comprise a rotary means, which generally turns about a horizontal axis, and a plurality of working units or assemblies - for example, welders - mounted on the rotary means and angularly spaced from each other around the axis of rotation of the rotary means, along a working circumference.

The operating unit generally comprises parts for supporting the continuous web and disposed along the working circumference, between the working units, for example, to ensure that the portion of web being processed by the contiguous working units is suitably tensioned.

In use, the working units and the supporting parts rotate in synchrony with the web - that is to say, the web is stationary relative to the wheel, allowing the operating units to work on the web while the web is fed along the machine in which the wheel is mounted. For example, the rotary operating unit may be used to weld a continuous web to make absorbent articles or nappies, for example, to weld the side gathers of nappy pants.

Document US9993370 discloses an operating unit used for welding a continuous web to form nappies.

The operating unit described comprises a plurality of working units or tools, which are used for welding and which are angularly equispaced and supported by a rotary means, and web supporting plates, which extend from each working unit, upstream and downstream thereof.

In other examples, the rotary operating unit may be used to weld a continuous web for packaging food and confectionery products, be they solid, such as chocolates or sweets, or liquid or semi-solid; for making beverage bottles and brick packs; for making pouches and bags to contain products of the tobacco industry, products of the cosmetic industry, products of the pharmaceutical industry or products of the personal and home care industry. Generally speaking, the continuous web processable with the operating unit according to this disclosure may be used to make packages, pouches or bags to contain liquid or solid products. One drawback of prior art solutions is that when a web is present on the operating unit, at least partly wrapped thereon, it is very difficult to be able to turn the unit relative to the web, that is to say, letting the web remain stationary while the operating unit rotates under it.

In effect, the presence of the web on the wheel and also wrapped on the supporting plates between the working units makes it difficult or even impossible to rotate the wheel, for example, to perform maintenance on the working units or to check their conditions with the machine stopped.

That is because, usually, the wheel must be rotated so that the wheel devices that have to be checked or repaired can be brought to a maintenance zone allowing access to the unit itself.

At present, to be able to do this, it is necessary to cut the web, which might even be taut, in order to be able to turn the wheel freely.

When maintenance has been completed, it is then also necessary to join the previously separated ends together again or to pull segments of web from the machine in order to re-establish the continuity of the web so that the system can return to normal operating conditions. The need therefore remains for rotary operating units which are capable of processing continuous webs and which are manageable in maintenance, for example, on their working units, without necessarily also having to operate on the web.

In this context, this disclosure proposes a rotary operating unit capable of overcoming at least some of the disadvantages of the prior art described above and of meeting the above mentioned need.

Aim of the invention

More specifically, this invention has for an aim to provide a rotary operating unit or wheel for processing a continuous web and which allows maintenance on the components of the wheel to be carried out in a practical manner.

This aim is achieved by a rotary operating unit comprising the technical features set out in one or more of the appended claims. The dependent claims correspond to possible different embodiments of the invention. According to a first aspect of it, this invention relates to a unit or wheel for processing a continuous web, where the web being processed is wrapped on at least one portion of the processing unit.

The processing unit comprises a rotary means that rotates about an axis of rotation that substantially defines a hub of the unit.

The processing unit comprises a plurality of working units or assemblies, that is to say, units which are used to perform the required processes on the web, such as welding, for example, and which are supported by the rotary means.

Generally speaking, the working units are movable between a configuration where they are disengaged from the web, and a configuration where they are engaged with the web to perform the specific process they are designed for.

In practice, the web is processed, for example, welded, by the working units while the wheel rotates, with at least some of the units in the web engaged configuration where they operate along a stretch of a feed path.

In a preferred embodiment, the working units extend radially from the rotary means and are angularly spaced from each other around the axis of rotation; preferably, the working units are equispaced from each other.

The working units may be movable towards and away from the axis of rotation, for example, to vary the outer circumference of the wheel, for example, to adapt to the size of the web being processed.

According to an aspect of this disclosure, the processing unit comprises a system for supporting the continuous web, comprising a plurality of continuous web support units interposed between the working units. Advantageously, the support units each comprise at least one roller that rotates about its axis of rotation, which is parallel to the axis of rotation of the rotary means and of the processing unit so that the web is supported by the rollers.

That way, advantageously, by keeping the working units in the web disengaged configuration, the wheel can rotate under the web thanks to the presence of the rollers. The web remains stationary while the rollers and the wheel roll under the web.

The working units and the support units at least partly define a main feed path of the continuous web.

According to an aspect, the continuous web supporting system comprises at least one support belt which is at least partly wrapped around the rollers and on which the web being processed is disposed.

The continuous web is disposed on the support belt with at least one portion of its transverse section, that is to say, considering a transverse section of the continuous web, a part of that transverse section is disposed on the support belt for the full length of the continuous web.

In use, the support belt is positioned on the rollers and the continuous web being processed is positioned at least partly on the support belt.

Preferably, the support system comprises a portion of support belt along the entire portion of the wheel on which the continuous web is wrapped. That way, the portion of continuous web wrapped around the wheel is positioned, for its full length and at least part of its width, on the support belt. Advantageously, if the wheel needs to be rotated under the continuous web being processed, it is the support belt that moves relative to the rollers, thereby avoiding any possible damage to the web on account of the wheel rotating.

According to another aspect, the continuous web support system comprises a retaining belt for holding the continuous web on the support belt.

The retaining belt extends at least partly in parallel with the support belt and is coupled thereto to hold the continuous web on the support belt. Preferably, the support system comprises a portion of retaining belt along the entire portion of the wheel on which the continuous web is wrapped. That way, the portion of continuous web wrapped around the wheel is held, for its full length and at least part of its width, on the support belt by the retaining belt.

Advantageously, the continuous web being processed is sustained between the support belt and the retaining and can thus hold a well-defined position when the wheel rotates under the support belt.

According to an aspect of this disclosure, the rollers are disposed at the vertices of a polyline, that is to say, they themselves define the vertices of a polyline along which the continuous web is disposed.

Advantageously, the working units operate on one or more segments of the continuous web defined by the open polyline.

According to an aspect of it, this disclosure relates to a method for processing a continuous web comprising a step of supporting the continuous web at least partly on a processing unit.

The method advantageously comprises a step of rotating the processing unit about an axis of rotation while keeping the web stationary relative to that axis of rotation.

The processing unit rotates under the continuous web which, instead, remains stationary. This step of rotating may be part of a step of performing maintenance on the processing unit.

According to an aspect, the step of rotating comprises a step of transferring at least one working unit of the processing unit into a maintenance zone. According to an aspect of it, this disclosure relates to a product comprising a segment of a continuous web processed with a processing unit according to any of the aspects described herein and/or with a processing method according to any of the aspects described herein.

According to an aspect, the product is an absorbent product for sanitary use.

Further features and advantages of the invention are more apparent in the exemplary, hence non-limiting description which follows of a preferred but non-exclusive embodiment of a unit for processing a continuous web.

Brief description of the drawings

The description is set out below with reference to the accompanying drawings which are provided solely for purposes of illustration without restricting the scope of the invention and in which:

- Figure 1 shows a schematic front view of a possible embodiment of a processing unit;

- Figure 2 shows a schematic front view of a detail of the processing unit of Figure 1 .

Detailed description of preferred embodiments of the invention

With reference to Figure 1 , the numeral 1 denotes in its entirety a unit or wheel for processing a continuous web W, generally a multilayer web, where the web processed is wrapped on at least one portion 2 of the unit 1 . The unit 1 comprises a rotary means 3 that rotates about an axis of rotation R3 that substantially defines a hub of the unit 1 ; The unit 1 rotates about the axis R3. The processing unit 1 comprises a plurality of working units or assemblies 4, 5, that is to say, units which are used to perform the required processes on the web W, such as welding, for example, and which are supported by the rotary means 3.

Generally speaking, the working units 4, 5 are movable between a configuration where they are disengaged from the web W, and a configuration where they are engaged with the web to perform the specific process they are designed for. The numeral 5 in Figure 1 denotes, for example, a working unit in the configuration where it is disengaged from the web W.

Looking at Figure 1 , the working unit 5 is positioned, for example, in a maintenance zone ZM where it can, for example, be checked, cleaned or repaired.

In practice, the web W is processed, for example, welded, by the working units 4, 5 while the wheel 1 rotates, with at least some of the units 4 in the configuration where they are engaged with the web W to operate on the web, for example at the portion 2 of the wheel 1 on which the web W is wrapped.

In the preferred embodiment where processing comprises welding, the units 4, 5 may comprise, for example, a gripper mechanism that is movable between an open configuration, corresponding to the non-operating configuration, and a closed configuration, corresponding to the operating configuration.

The gripper mechanism comprises, for example, a sonotrode and an anvil which are movable between a spaced-apart position where they are disengaged from the web, and a close-together position where they are engaged with the web to weld the web by ultrasonic welding.

In a preferred embodiment illustrated by way of example, the units 4 extend radially from the rotary means 3 and are angularly spaced from each other around the axis of rotation R3; preferably, as illustrated, the units 4 are equidistant from each other. In a preferred embodiment, the units 4 are movable towards and away from the axis of rotation R3, for example, to vary the spacing between the corresponding processes performed on the web W.

The unit 1 comprises a system for supporting the continuous web W, generically denoted by the reference character S, to support the web W when it is wrapped on the wheel 1 .

The support system S helps to keep the web W suitably tensioned, for example as a function of the processes to be performed on it.

The system S comprises at least some of the working units 4 which, preferably at least in the configuration where they are engaged with the web W, support the web and/or define an opposing contact surface for it.

As illustrated, the system S comprises a plurality of support units 6 for supporting the web W and interposed between the working units 4.

The working units 4 and the support units 6 at least partly define a main feed path of the continuous web W.

The main feed path of the continuous web W extends preferably, at least partly, around an axis that coincides with the axis of rotation R3. Advantageously, the support units 6 each comprise at least one roller 7 - two in the example illustrated - which is rotatable about a respective axis of rotation R7, parallel to the axis of rotation R3 of the rotary means 3 and of the unit 1 .

In the embodiment illustrated by way of example, the support units 6 each comprise a load-bearing structure 8 on which the rollers 7 are mounted and which is connected to the rotary means 3.

The web W is therefore supported by the rollers 7 on which it lies; that way, advantageously, by keeping the working units in the web disengaged configuration, the wheel can rotate under the web thanks to the presence of the rollers. In practice, the unit 1 rotates under the web W about the axis R3 while the web remains stationary relative to that axis, thanks to the rollers 7 rolling under it.

The support system S comprises at least one flexible support element or belt 9 for supporting the web W, which is at least partly wrapped on the rollers 7.

The continuous web W is preferably disposed on the belt 9 with at least one portion of its transverse section; that is to say, considering a transverse section of the web W, a part of that transverse section is disposed on the support belt 9 for the full length of the web W.

As illustrated, the belt 9 is positioned on the rollers 7 and the continuous web W being processed is positioned at least partly on the belt 9. Preferably, the support system S comprises a portion of the belt 9 along the entire portion of the wheel on which the continuous web W is wrapped. That way, the portion of continuous web W wrapped around the wheel 1 is positioned, for its full length and at least part of its width, on the support belt 9.

Advantageously, when the wheel 1 needs to be rotated under the web W while keeping the web W stationary relative to the axis of rotation, it is the belt 9 that moves relative to the rollers 7, thereby avoiding any possible damage to the web W.

In the preferred embodiment illustrated, the support system S for supporting the continuous web W comprises a flexible retaining element or belt 10 for holding the continuous web W on the belt 9.

The belt 10 extends at least partly in parallel with the belt 9 and is coupled thereto to hold the web W.

Preferably, the transverse dimension of the belt 10, that is, the dimension measured parallel to the axis R3, is smaller than the transverse dimension of the belt 9, that is, the dimension measured parallel to the axis R3. Preferably, the system S comprises a portion of belt 10 along the entire portion of the wheel 1 on which the continuous web W is wrapped.

That way, the portion of web W wrapped around the wheel 1 is held, for its full length and at least part of its width, on the belt 9 by the retaining belt 10. Advantageously, the web W is sustained between the belt 9 and the belt 10 and can thus remain at a well-defined position when the wheel 1 rotates under the belt 9 while the latter remains stationary relative to the axis of rotation R3.

In other words, the support system S comprises retaining means for holding a portion of the continuous web W where, preferably, no processes need to be performed.

The retaining means comprises the first flexible element 9 and the second flexible element 10, which extend at least partly around the axis of rotation R3 of the rotary means 3 and between which a portion of web W is disposed. Looking at Figure 1 in particular, the rollers 7 define the vertices of an open polyline and determine a corresponding and similar positioning of the web W on the wheel 1 .

The aforementioned main feed path of the continuous web W on the wheel 1 follows the shape of the open polyline.

Advantageously, the working units 4 operate on one or more segments of the continuous web W defined by the open polyline along which the web W is disposed.

To optimize costs, there is a growing need to use the same operating unit 1 to make different product formats by varying the working spacing of the unit. As already mentioned, the angular distance between one working unit 4 and the working unit 4 adjacent to it determines the spacing of the work done on the continuous web W.

To vary the working spacing, it is necessary to vary the radial positioning of the working units relative to the axis of rotation of the rotary means 3. Varying the working spacing involves varying the distance between each working unit 4 and the working unit 4 adjacent to it.

Preferably, therefore, a radial movement of the working units 4 corresponds to a movement of the rollers 7 towards and away from the axis of rotation R3, that is to say, the rollers 7 are movable towards the axis of rotation R3 and away from it.

Preferably, the rollers 7 are movable towards and away from the axis of rotation R3 through corresponding movements of the respective load- bearing structures 8.

The unit 1 comprises a system for tensioning the continuous web W and/or the support belt 9 and/or the retaining belt 10.

The tensioning system may comprise suitably coordinated, distinct systems for the web and each of the belts or a common tensioning system for the support and retaining belts and a dedicated tensioning system for the continuous web or other, different combinations for adjusting the tension of the web and each of the belts.

The tensioning system, schematically represented as a block 11 for simplicity of illustration, allows adjusting the tension of the web and belts on the wheel 1 , for example, during a format changeover, or to slacken and release the wheel or to repair it in order to set the unit 1 in operation again. Advantageously, the presence of the rollers under the continuous web being processed and/or at least under the support belt, allows rotating the wheel even in the presence of the web and belts and keeping the web and belts stationary relative to the axis of rotation.

When operating on the working units, for example, the wheel may be rotated under the web or belts while keeping the web and belts stationary relative to the axis of rotation. Rotating the wheel may, for example, bring each working unit to the configuration where it is disengaged from the web, for example, down, with reference to Figure 1 , without cutting or damaging the continuous web being processed.

A method for processing the continuous web W comprises a step of supporting the continuous web W at least partly on the processing unit 1. The method comprises a step of rotating the processing unit 1 about the axis of rotation R3 under the continuous web W while keeping the web W stationary relative to the axis of rotation R3.

Advantageously, the step of rotating comprises a step of transferring at least one working unit 4, 5 of the processing unit into the maintenance zone ZM. The method comprises a step of performing maintenance on a working unit 4, 5 of the processing unit 1 , where this step comprises the step of rotating. Also an object of this disclosure is a product, preferably an absorbent product for sanitary use, comprising a segment of a continuous web W processed with the processing unit 1 and/or with the corresponding processing method.