EP1533112B1

EP1533112B1 - Apparatus for manufacturing multiple-ply paper products by knurling

Info

Publication number: EP1533112B1
Application number: EP04025879A
Authority: EP
Inventors: Massimo Nofori
Original assignee: Industrie Cartarie Tronchetti SpA
Current assignee: Industrie Cartarie Tronchetti SpA
Priority date: 2003-11-24
Filing date: 2004-11-02
Publication date: 2012-09-19
Anticipated expiration: 2024-11-02
Also published as: ITMI20032279A1; PL1533112T3; ES2395271T3; EP1533112A1

Description

The present invention relates to an apparatus for manufacturing multiple-ply paper products by knurling.
The invention relates in particular to so-called "tissue" products, such as toilet paper, paper handkerchiefs, rolls of absorbent paper, et cetera, constituted by at least two plies.
As is known, joining the plies of tissue paper by means of paste causes a reduction in the softness of the finished product.
In order to obviate that drawback, many tissue products in which softness is required are not pasted but are instead knurled.
Unfortunately, the knurling systems known in the art have a drawback in that the part of ply that is deformed by the knurling tools has the appearance of a line that is generally not arranged symmetrically with respect to the product.
This has always been considered as an aesthetic drawback, because it gives the product a "defective" appearance.
US-5622734 discloses an apparatus for producing crimp-bonded fibrous cellulosic laminate comprising a plurality of crimp elements configured in a discontinuous pattern aligned on an axis that is parallel to the cross machine direction. The crimp elements are arranged on one side of an anvil rod, opposite to a drive roll.
The aim of the present invention is to provide an apparatus for manufacturing multiple-ply paper products by knurling that overcomes the drawbacks of the cited prior art.
A particular object of the invention is to provide an apparatus that is capable of maintaining high softness characteristics of the product without using paste and at the same time of solving the discontinuities of conventional knurling.
A further object of the invention is to provide an apparatus that allows to produce the knurling wheels by laser engraving and etching and therefore with reduced costs.
This aim and these and other objects that will become better apparent hereinafter are achieved by an apparatus for manufacturing multiple-ply paper products as claimed in the accompanying claims.
Further characteristics and advantages of the present invention will become better apparent from the following detailed description of preferred but not exclusive embodiments thereof, illustrated by way of non-limiting example in the accompanying drawings, wherein:

Figure 1 is a partial front view of the apparatus according to the prior art ;
Figure 2 is a front view of the apparatus according to the prior art ;
Figure 3 is a partial side view of an arrangement of a contrast roller and of knurling wheels;
Figure 4 is a view, similar to Figure 2, of an apparatus according to the invention, provided with two knurling wheel holders;
Figure 5 is a partial side view of the arrangement of the contrast roller and of the knurling wheels of the apparatus of Figure 4;
Figure 6 is a partial perspective view, illustrating in detail the knurling wheel holders for individual knurling wheels;
Figure 7 is a view, similar to Figure 2, of an apparatus according to a further aspect of the invention, provided with intermediate supports;
Figure 8 is a partial perspective view of the arrangement of the contrast roller and of the knurling wheels of the apparatus of Figure 7;
Figure 9 is a flat projection view of an example of a design, illustrating an example of embodiment of decorative patterns;
Figure 10 is a flat projection view of an example of a design;
Figure 11 is a flat projection view of the protrusions suitable to form the design of Figure 10;
Figure 12 is a flat projection view of a further example of design;
Figure 13 is a flat projection view of the protrusions suitable to form the design of Figure 12;
Figure 14 is a flat projection view of a further example of design;
Figure 15 is a flat projection view of the protrusions suitable to form the design of Figure 14;
Figure 16 is a flat projection view of a further example of design;
Figure 17 is a flat projection view of the protrusions suitable to form the design of Figure 16;
Figure 18 is a flat projection view of a further example of design;
Figure 19 is a flat projection view of the protrusions suitable to form the design of Figure 18.

With reference to the cited figures, an apparatus according to the prior art, generally designated by the reference numeral 1, comprises a knurling wheel holder 2 which is substantially constituted by a shaft 3 that supports a plurality of knurling wheels 4, which act in contrast with a contrast roller 5 in order to join two plies of paper into a single ribbon 6.
The knurling wheels 4 have dimensions that are six to thirtysix times larger than those of conventional knurling wheels. By way of example, while conventional knurling wheels have a width comprised between 5 and 30 mm, the knurling wheel according to the present invention is 181 mm wide.
The knurling wheel has an operating principle that is similar to that of a conventional knurling wheel but, by having a larger surface available, it allows to create decorations in relief which are then transferred to the paper.
It is evident from the drawings that the decorative patterns, which in the illustrated example are wavy, are arranged so that, despite appearing to be separate, they allow the knurling wheel to have a continuous contact with the paper and the contrast roller, preventing vibrations that would be harmful for the paper and the knurling wheel.
The spacing A between each pattern allows to decorate with continuity in a transverse direction despite using a plurality of knurling rollers 4 rather than a single roller. All this is clearly beneficial to the dimensions of the knurling wheels, which in the specific case have a diameter of 150 mm and despite the intense pressures involved do not flex, because their transverse dimension is 181 mm, and therefore is short with respect to the diameter.
The distance between the knurling wheels, designated by the reference letter B in Figure 1, is such as to keep the patterns 7 with a minimal variation from knurling wheel to knurling wheel, which is reflected on the paper 6 as a design continuity effect.
The knurling wheel is provided by using a material that is suitable to undergo laser engraving and etching and therefore has a low cost.
With an appropriate arrangement of the decorative patterns 7, one always has a decoration of the roll that is capable of hiding the asymmetries. Continuity of contact between the contrast roller and the knurling wheel is maintained also by virtue of the width of the knurling wheel.
Figure 9 illustrates a particular embodiment of the decorative patterns, designated by the reference numeral 17, which are characterized by the insertion, between one design and the next, of a series of protrusions 18 that allow contact between the knurling wheel and the contrast roller but do not change the final effect of the decoration, because they blend with the embossing of the paper.
By using a system with a contrarotating cylindrical brush, effective cleaning of the knurling wheels is ensured.
Moreover, the apparatus allows to provide a decoration on an existing embossed base by using a knurling wheel in which the protrusions are higher than the protrusions of the base.
Figures 4 and 5 illustrate an embodiment of the apparatus, designated by the reference numeral 101, according to the invention.
Due to the intense forces generated by the thrust of the knurling wheels 4 against the contrast roller 5, the contrast roller 5 may flex during rotation, reducing the cohesion of the paper plies.
In order to obviate this drawback, it is possible to increase the diameter of the contrast roller 5 in order to increase its flexural strength, but this leads to high costs.
In order to avoid generating these costs and avoid further increases in the complexity of the machine, the knurling wheels 4 can be made to operate in mutually opposite directions on the same contrast roller 5, so as to cancel out the bending. With such arrangement one is free to vary the distance B at will.
In the illustrated example, by way of indication, the distance between the knurling wheels 4 on the same shaft is approximately 210 mm.
The knurling wheels 4 can be supported by a single supporting shaft, as described above, or individually by a holder for each knurling wheel, as shown schematically in Figure 6, which illustrates individual knurling wheels 4, each of which is supported by a holder 44 applied to a supporting beam 14.
An inflatable pad 8 is preferably interposed between the knurling wheels 4 and the supporting beam 14.
Figures 7 and 8 illustrate a further embodiment of the single-shaft knurling wheel holder system, in which the knurling wheels 4 are associated with the shaft 3, which is pushed at its two ends by power arms 10.
The power arms 10 act on a beam 11, which includes a series of intermediate supports 9 for the shaft 3, which avoid the flexing of the shaft.
In practice it has been found that the invention achieves the intended aim and objects, providing an apparatus that is capable of maintaining high characteristics of softness of the product without using adhesive and at the same time of solving the aesthetic problem of conventional knurling.
The apparatus according to the invention joins two or more plies of tissue paper and simultaneously decorates them by means of the impression left by the knurling tool.
The apparatus allows the plies to pass between the contrast roller and a series of knurling wheels, which are appropriately decorated in relief and are suitable, by means of the pressure applied to the contrast roller, to join the plies that are interposed between the contrast roller and the knurling wheel unit.
The apparatus according to the invention allows to join the paper plies and at the same time decorate them by using the technique of permanent deformation of the paper, which by virtue of the deformation also assumes a different coloring and impression and allows to recognize the decorative pattern.
Another characteristic of the invention consists in the particular arrangement of the decorative pattern along the circumference and in the transverse direction of the decorated wheel.
The apparatus according to the invention is susceptible of numerous modifications and variations, within the scope of the appended claims. All the details may be replaced with technically equivalent elements.
The materials used, as well as the dimensions, may of course be any according to requirements and to the state of the art.

Claims

An apparatus for manufacturing multiple-ply paper products by knurling, comprising a knurling wheel unit (2, 3, 4, 14, 44) constituted by a plurality of knurling wheels (4), each of which cooperates with at least one contrast roller (5) in order to decorate, by knurling, at least one paper ply and in order to decorate and join at least two paper plies, each of said knurling wheels (4) being provided with relief patterns (7) arranged to provide a continuity of contact with the paper and the contrast roller (5); said apparatus being characterized in that it comprises two knurling wheel holders (2), which are arranged mutually opposite with respect to said contrast roller (5).
The apparatus according to claim 1, characterized in that each knurling wheel (4) is relatively long in an axial direction and has a large number of relief patterns (7).
The apparatus according to one or more of the preceding claims, characterized in that said patterns (7) are spaced with respect to each other by a distance that is comparable to the distance between the knurling wheels (4), so as to maintain the patterns (7) with a minimal variation among the knurling wheels (4), which produces an effect of design continuity on the knurled paper.
The apparatus according to one or more of the preceding claims, characterized in that said spacing between the patterns (7) allows to decorate with continuity in a transverse direction by using a plurality of knurling wheels (4).
The apparatus according to one or more of the preceding claims, characterized in that the axial dimension of each knurling wheel (4) is comparable with its diameter.
The apparatus according to one or more of the preceding claims, characterized in that said knurling wheels (4) are made of a material that is suitable to undergo laser engraving and etching.
The apparatus according to one or more of the preceding claims, characterized in that said knurling wheel (4) is provided with protrusions that are higher than the protrusions of an already embossed paper ply, in order to provide a decoration on said already embossed paper ply.
The apparatus according to one or more of the preceding claims, characterized in that said knurling wheels (4) are supported by a single supporting shaft (2).
The apparatus according to one or more of the preceding claims, characterized in that said single shaft (2) is pushed at its two ends by power arms (10).
The apparatus according to one or more of the preceding claims, characterized in that said power arms (10) act on a beam (11), which comprises a series of intermediate supports (9) for said single shaft (2) and prevent said shaft (2) from flexing.
The apparatus according to one or more of the preceding claims, characterized in that protrusions are interposed between said decorative patterns and allow contact between the knurling wheel (4) and the contrast roller (5) but do not vary the final effect of the decoration because they are blended with the embossing of the paper.
The apparatus according to claim 1, characterized in that said knurling wheels (4) are supported individually by a knurling wheel holder (44) applied to a supporting beam (14).
The apparatus according to claim 12, characterized in that an inflatable pad (8) is interposed between said knurling wheels (4) and said supporting beam (14).