EP1974900A1

EP1974900A1 - Device and method for a point-to-point joining of web products and product obtained thereby

Info

Publication number: EP1974900A1
Application number: EP07425179A
Authority: EP
Inventors: Gianni Gelati
Original assignee: Euroincis Srl
Current assignee: Euroincis Srl
Priority date: 2007-03-26
Filing date: 2007-03-26
Publication date: 2008-10-01

Abstract

The invention consists in a device, adapted to a point-to-point joining of web products (1, 1'), which comprises at least one pair of embossing rollers (3, 3'), a pair of pressure rollers and a gluing unit (4).

On the skirt of the embossing rollers (3, 3') is engraved a plurality of slanting spiral lines (6), perfectly congruent and disposed with the same orientation on both rollers (3,3 '), which create on the web products (1,1') impressions (8, 8') slanting in opposite directions, which cause, at their crossing points, the creation of rhomboid shaped joining points (9) when the web products (1, 1') are assembled together and brought into contact with each other by the embossing rollers (3, 3').

The present invention further comprises a method for a point-to-point joining of web products (1, 1') by means of said device and the product obtained thereby.

Description

The present invention relates to a device and to a method for a point-to-point joining of web products and to the product obtained thereby.
Devices for "tip-to-tip" joining of two or more web products, in particular of two or more webs of paper, are widely known and used.
A typical application of such devices is the production of paper products with two or more plies such as, for example, rolls of kitchen towels, rolls of toilet paper, paper handkerchiefs, etc.
Said devices comprise a pair of embossing rollers, a pair of pressure rollers coupled with the embossing rollers and at least one gluing unit, which applies to one of the webs of paper an adhesive material which makes the paper webs adhere to each other when they are pressed one against the other, or in any case brought into contact with each other, on passing between the embossing rollers.
If webs of non-woven fabric are used, the embossing rollers must be thermostated.
Devices for "tip-to-tip" joining and the operation thereof will not be further described because they are per se known.
Joining is called "tip-to-tip" because a plurality of pointed protuberances is formed on the skirt of the embossing rollers, which form protruding "tips" on the webs of paper: when the two webs of paper, on passing between the embossing cylinders, are brought into contact with each other, the "tips" of the two webs are made to adhere to each other by the adhesive material applied to the "tips" of one of the webs.
Devices of the prior art for "tip-to-tip" joining have a serious drawback in that, to make the paper webs to adhere correctly, it is necessary for the embossing rollers to be "in phase" with each other so that, at the time of joining of the webs, the "tips" of one of the webs coincide perfectly with the "tips" of the other web: this makes (relatively) frequent interventions by the operators necessary to put the two embossing rollers back "in phase", with a resulting increase in the running costs of the device and a decrease in the productivity thereof.
Object of the invention is to overcome the above-mentioned drawbacks presented by the devices for "tip-to-tip" joining of the prior art.
In particular, an object of the invention is to produce a device that does not require (frequent) interventions by the operators to put the embossing rollers back "in phase".
Another object of the invention is to give the finished product greater softness and pliability.
These objects are achieved by means of a device for a point-to-point joining having at least the characterising features indicated in the independent claim 1 and operating according to a method comprising at least the functional steps indicated in the independent claim 9.
Further advantageous characteristics of the invention form the subject matter of the dependent claims.
In particular, a device according to the invention for a point-to-point joining of web products comprises a pair of embossing rollers, on the skirts of which is engraved a plurality of slanting spiral lines, perfectly congruent and disposed with the same orientation on both embossing rollers.
In the present description, the term "perfectly congruent" is used to indicate that the slanting lines engraved on the skirts of the two embossing rollers are perfectly identical to each other.
Further characteristics and advantages of the invention will be made clearer by the detailed description that follows, referring to a purely exemplifying and therefore non-limiting embodiment thereof, illustrated in the appended drawings, in which:

Figure 1 shows diagrammatically a device for joining together two web products;
Figure 2 shows a front view of a pair of embossing rollers belonging to the device of Figure 1 and realised according to the invention;
Figure 3 shows a diagrammatic enlarged view of the detail of one of the embossing rollers highlighted by A in Figure 2;
Figure 4 shows a front view of the detail A shown in Figure 3;
Figure 5 shows a diagrammatic enlarged view of a portion of the final product, the impressions created on the web products by the embossing rollers of Figure 2 and the joining points of the web products at the crossing points of said impressions.

In the appended figures like elements will be designated by the same reference numerals.
In the appended figures 1 and 1' denote the web products to be joined; 2 and 2' denote the pressure rollers which press the web products (1, 1') against the embossing cylinders; 3 and 3' denote the embossing cylinders; 4 denotes a gluing unit that applies an adhesive material to one of the web products (1,1'); 5 denotes the product obtained by joining together the web products (1, 1'); 6 denotes the slanting spiral lines engraved on the skirt of the embossing cylinders (3, 3'); 7 denotes the ridges between the two adjacent engraved lines 6; 8 and 8' denote the slanting impressions created in the web products (1, 1') by the embossing cylinders (3, 3') and 9 denotes the joining points formed at the crossing points of the raised impressions 8 and 8'.
Figure 1 shows diagrammatically a device for joining together two web products, preferably two webs of paper of the type used to produce rolls of paper material and/or handkerchiefs.
As shown in Figure 1, each of the webs (1, 1') passes between a pressure roller (2, 2') and an embossing roller (3, 3') where it receives slanting impressions (8, 8'; Figure 5), one of the webs of paper (the web 1 in the embodiment of Figure 1) receives from a gluing unit 4 - on its impressions 8 - a layer of an adhesive material (not described because it is per se known) and lastly the webs (1, 1') pass between the embossing rollers (3, 3'), rotating in opposite directions, which bring them into contact with each other to form the end product 5.
The impressions (8, 8') are raised with respect to the plane of the respective web of paper (1, 1').
The device diagrammatically illustrated in Figure 1 differs from a device of the prior art for the "tip-to-tip" joining in that on the skirt of the embossing rollers (3, 3') is engraved a plurality of slanting spiral lines 6, disposed with the same orientation on both embossing rollers (3, 3') and perfectly congruent.
Said slanting spiral lines 6 can be seen clearly in Figure 2, which shows a front view of a pair of embossing rollers (3, 3') realised according to the invention; the arrows F and F' in Figure 2 indicate that the embossing rollers (3, 3') rotate in opposite directions.
The slanting lines 6 engraved on the skirt of the embossing rollers (3. 3') create on the webs (1, 1') raised impressions (8, 8'), slanting in opposite directions, which cause the creation, at their crossing points, of joining points 9 (Figure 5) of the webs (1, 1) when said webs are brought together by the embossing rollers (3, 3').
The lines 6 (and the impressions 8 and 8', respectively, created by the lines 6) are inclined with respect to the axis of the relative embossing roller (3, 3') by an angle preferably between 30° and 60° and, more preferably, of 45°.
Figure 3 shows a diagrammatic enlarged view of the detail of the embossing roller highlighted by A in Figure 2.
As shown in said figure, the spiral lines 6 advantageously consist of grooves with a curved profile, parallel to each other, separated by ridges 7 which create on the webs (1, 1') the slanting raised impressions (8, 8') but, without departing from the scope of the invention, the spiral lines 6 can consist of rectangular, trapezoid or triangular (V-) shaped grooves (not shown in the appended figures for the sake of simplicity of the graphic representation) separated by the ridges 7.
Purely by way of a non-limiting example, the spiral lines 6 have a pitch of about 1.77 mm, the grooves with a curved profile have a depth of about 0.5 mm and the ridges 7 are about 0.3 mm wide at the top.
Figure 4 shows a front view of the detail A shown in Figure 3; visible in Figure 4 are the grooves with a curved profile, parallel to each other, which form the spiral lines 6 and the ridges 7, which separate two adjacent spiral lines 6.
The spiral lines 6 formed on the embossing roller 3' are identical to those formed on the embossing roller 3 and shown in Figures 3 and 4.
Figure 5 shows diagrammatically a portion of the end product 5, enlarged to show the slanting impressions (8, 8') created on the webs (1, 1') by the embossing rollers (3, 3') of Figure 2 and the joining points 9, situated at the crossing points of said impressions 8 ad 8'.
The joining points 9 are rhomboid shaped and their sides are inclined, with respect to the longitudinal axes of the embossing rollers (3, 3'), like the impressions (8, 8') created by the ridges 7 which separate two adjacent spiral lines 6.
Purely by way of a non-limiting example, if the spiral lines 6 have a pitch of about 1.77 mm, the distance between two adjacent rows of joining points 9 is about 2.5 mm.
As is made clear by Figure 5 (and as has been verified experimentally by the Applicant), a small difference in phase of the embossing rollers (3, 3') causes only a small shift of the impressions 8 with respect to the impressions 8' and, consequently, only a small shift of the joining points 9.
Therefore, (frequent) interventions by the operators to put the embossing rollers back "in phase" are not necessary.
It should be noted that, in the device of the prior art for a "tip-to-tip" joining, a small difference in phase of the embossing rollers involves that the "tips" of one of the webs no longer coincide with the "tips" of the other web, making it impossible (or at least very difficult) to join the two webs correctly.
Therefore, (frequent) interventions by the operators to put the embossing rollers back "in phase" are necessary.
If the end product were formed by joining together three webs of paper, similarly to what occurs in the devices of the prior art for the "tip-to-tip" joining, the third web of paper would be placed between the webs (1, 1') before they pass between the embossing rollers (3, 3') and the device would comprise a further gluing unit that applies a layer of an adhesive material at the impressions 8' of the other web (the web 1' in the embodiment of Figure 1).
The third web of paper and the further gluing unit are omitted in Figure 1 for the sake of simplicity of the graphic representation.
Experimental tests carried out by the applicant have further shown that the diagonal embossing of the webs 1 and 1' disposes the fibres of said webs so as to give the end product 5 a greater softness and pliability.
The method for a point-to-point joining of two webs by means of the joining device previously described comprises at least the steps of:

passing the webs (1 and 1', respectively) between an embossing roller (3 and 3', respectively) and the relative pressure roller (2 and 2', respectively) to create a plurality of raised impressions (8 and 8', respectively), the impressions (8, 8') created on the webs (1, 1') slanting in opposite directions;
passing one of the two webs (1, 1') in a gluing unit 4;
assembling together the two webs (1, 1') and bringing them into contact with one another by means of the embossing rollers (3, 3'), causing the formation of a plurality of joining points (9) at the crossing points of the impressions 8 and 8'.

In the embodiment described herein the web products point-to-point joined by means of the device and of the method of the present invention are paper webs but, without departing from the scope of the invention, it is possible to join point-to-point by means of the device and of the method of the present invention web products of any type, provided they lend themselves to being point-to-point joined by means of the above described device.
The product 5 obtained by point-to-point joining of at least two web products (1, 1'), according to the above method and by means of the device shown in the appended figures, also forms the subject matter of the present invention.
A person skilled in the art can make to the above described device and method all the changes suggested by the personal experience and by the natural evolution of the art, without thereby departing from the scope of the invention, as set forth in the appended claims.

Claims

A device for a point-to-point joining of web products (1, 1'), comprising a pair of embossing rollers (3, 3') rotating on opposite directions, a pair of pressure rollers (2, 2') coupled with said embossing rollers (3, 3') and at least one gluing unit (4) associated with one of the embossing rollers (3, 3'), characterised in that on the skirts of the embossing rollers (3, 3') is engraved a plurality of slanting spiral lines (6), alternating with ridges (7), disposed with the same orientation on both embossing rollers (3, 3').
A device as in claim 1, characterised in that said ridges (7) on the skirts of the embossing rollers (3, 3') create on the web products (1, 1') raised impressions (8, 8') slanting in opposite directions, which cause, at their crossing points, the creation of joining points (9) of the web products (1, 1') when said web products (1, 1') are put together and brought into contact with each other by the embossing rollers (3, 3').
A device as in claim 1, characterised in that the lines (6) engraved on the skirts of the embossing rollers (3, 3') consist of curved, rectangular, trapezoid or triangular (V-) shaped grooves, parallel to each other, separated by ridges (7) which create on the web products (1, 1') the slanting, raised impressions (8, 8').
A device as in claim 2, characterised in that the joining points (9) are rhomboid shaped and their sides are inclined, with respect to the longitudinal axes of the embossing rollers (3, 3'), like the impressions (8, 8').
A device as in claim 1, characterised in that the lines (6) engraved on the skirt of each of the embossing rollers (3, 3') are inclined with respect to the axis of said embossing roller (3, 3') by an angle between 30° and 60°.
A device as in claim 5, characterised in that the lines (6) engraved on the skirt of each of the embossing rollers (3, 3') are inclined with respect to the axis of said embossing rollers (3 and 3', respectively) by an angle of 45°.
A device as in claim 3, characterised in that said spiral lines (6) have a pitch of about 1.77 mm, consist of grooves with a curved profile about 0.5 mm deep and are separated by ridges (7) about 0.3 mm wide at the top.
A device as in claims 2 and 7, characterised in that the distance between two adjacent rows of joining points (9) is about 2.5 mm.
A method for a point-to-point joining of web products by means of a point-to-point joining device according to at least one of the preceding claims, characterised in that it comprises at least the steps of:
- passing the web products (1 and 1', respectively) between an embossing roller (3 and 3', respectively) and the relative pressure roller (2 and 2', respectively) to create thereon a plurality of raised impressions (8 and 8', respectively), the impressions (8, 8') created on the web products (1, 1') slanting in opposite directions;

- passing one of the two web products (1, 1') in a gluing unit (4);

- assembling together the two web products (1, 1') and bringing them into contact with one another by means of the embossing rollers (3, 3'), causing the formation of a plurality of joining points (9) at the crossing points of the impressions (8, 8').
A product (5) obtained by a point-to-point joining of web products (1, 1') by means of a device according to at least one of claims 1-8 operating according the method as in claim 9.