GB2555634A

GB2555634A - A method for manufacturing a high precision protrusion roll

Info

Publication number: GB2555634A
Application number: GB1618732.0A
Authority: GB
Inventors: Schmitz Christoph
Original assignee: Concepts for Success C4S
Current assignee: Concepts for Success C4S
Priority date: 2016-11-07
Filing date: 2016-11-07
Publication date: 2018-05-09
Also published as: WO2018083321A1

Abstract

A method for manufacturing a high precision treatment roll, the method comprising the steps of providing a cylindrical roll (1000, fig.2A) and a plurality of arch shaped protrusions 1100 and an auxiliary sheet material (1400, fig.3B), forming apertures (1420, fig.3B) in said auxiliary sheet, positioning said protrusions in said apertures, connecting said protrusions to said auxiliary sheet in said apertures, positioning said auxiliary sheet with said arch shaped protrusions on the surface of said cylindrical roll such that the arch apex points 1219 are orientated inwardly towards a roll axis 1005 and portions of arch bend flanks 1220 extend outwardly, machining said outwardly extending portions of said arch bend flanks 1220, re-positioning and fixing said auxiliary sheet on the cylindrical roll such that the arch apex points 1219 are orientated outwardly and said machined arch bend flanks 1220 are orientated inwardly towards the roll axis 1005, wherein arch apex points 1219 of the protrusions exhibit a variation of a distance to said roll axis which is less than 20µm. The protrusions may be helical spring coils or wire meshes of rounded wires connected to the auxiliary sheet by welding or soldering.

Description

(54) Title ofthe Invention: A method for manufacturing a high precision protrusion roll Abstract Title: A method for manufacturing a high precision protrusion roll (57) A method for manufacturing a high precision treatment roll, the method comprising the steps of providing a cylindrical roll (1000, fig.2A) and a plurality of arch shaped protrusions 1100 and an auxiliary sheet material (1400, fig.3B), forming apertures (1420, fig.3B) in said auxiliary sheet, positioning said protrusions in said apertures, connecting said protrusions to said auxiliary sheet in said apertures, positioning said auxiliary sheet with said arch shaped protrusions on the surface of said cylindrical roll such that the arch apex points 1219 are orientated inwardly towards a roll axis 1005 and portions of arch bend flanks 1220 extend outwardly, machining said outwardly extending portions of said arch bend flanks 1220, re-positioning and fixing said auxiliary sheet on the cylindrical roll such that the arch apex points 1219 are orientated outwardly and said machined arch bend flanks 1220 are orientated inwardly towards the roll axis 1005, wherein arch apex points 1219 ofthe protrusions exhibit a variation of a distance to said roll axis which is less than 20pm. The protrusions may be helical spring coils or wire meshes of rounded wires connected to the auxiliary sheet by welding or soldering.

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-1 A METHOD FOR MANUFACTURING A

HIGH PRECISION PROTRUSION ROLL

Field of the invention

The present invention is a method for the manufacture of a roll that comprises protrusions on its outer surface, that exhibit a low variation of their height, respectively of the distance of the protrusion tip to the axis of the roll. Such high precision protrusions rolls may be used to treat materials such as web materials, such as by embossing or printing these web materials. In a particular application, such rolls may interact with a ultrasonic sonotrode

Background

It is well known in the art to use rolls with protrusions on their outer surface, for example for treating web materials in embossing, bonding or printing processes. It is also known that protrusions exhibiting a rounded tip may be advantageous as an anvil acting against a heated or otherwise energy providing roll for certain applications, see e.g. EPI 144187A1. However, the solution as described therein is difficult to manufacture, as it requires very laborious and hence expensive machining.

For certain applications, in particular in combination with ultrasonic bonding applications, it has been found to be advantageous to use protrusions with a rounded tip, that create an elongated imprint, see PCT/EP2016/058524 (unpublished), or see W02012042055A1 in the context of a flexible, preferably helical anvil.

However, for certain applications in particular in the context of ultrasonic bonding, it has been found, that sometimes a high accuracy may be required and/or that the deformation mechanism of flexible anvil member, in particular helical anvil member like helical coil springs, may result in insufficiently even treatment.

Henceforth there exists the challenge to overcome the described problems and to provide a way for easy manufacturing of rolls with precisely defined protrusion heights.

Summary

To this end, the present invention is a method for manufacturing a high precision treatment roll, which exhibits in cylindrical coordinates a treatment roll width 1, a radius r, and an angular component phi, and which comprises a center axis, aligned with the roll width, around which the roll is rotatably mounted, and a plurality of protrusions extending generally radially

-2outwardly from the roll. Each of the protrusions exhibits an arch-like shape with a bend portion comprising an arch apex point and two arch bend flanks tapering away from the arch apex point and optionally two support portions connected by the bend portion. Thereby, the arch apex point is positioned radially further away from the center axis relative to the bend portions of the arch or to the support portions, if present.

The method comprises the steps of

a) providing a cylindrical roll as a treatment roll blank, optionally a cylindrical auxiliary roll, a plurality of arch shaped protrusions, preferably of metal material, and an auxiliary sheet material;

b) forming apertures in a sheet of the auxiliary sheet material adapted to receive a plurality of the protrusions;

c) positioning portions of the protrusions in the apertures such that a first portion of a protrusion comprising the arch apex point is positioned on a first side of the auxiliary sheet, and portions of the arch bend flanks or arch supports extend through the apertures towards the opposite side of the auxiliary sheet;

d) connecting the protrusions to the auxiliary sheet in the apertures;

e) positioning the auxiliary sheet with the arch shaped protrusions on the surface of the treatment roll blank or the auxiliary roll, if present, such that the arch apex points are oriented inwardly towards the roll axis, and portions of the arch bend flanks or arch supports extend outwardly;

f) machining the outwardly extending portions of the arch bend flanks or the arch supports to a predetermined precision with regard to the distance to the axis;

g) re-positioning the auxiliary sheet on the treatment roll blank such that the arch apex points are oriented outwardly and the machined arch bend flanks or arch supports inwardly towards the axis;

h) fixing the repositioned auxiliary sheet on the treatment roll blank, wherein the arch apex points of the plurality of protrusions exhibit a variation of the distance to the roll axis which is less than 20pm, preferably less than 10 pm, more preferably less than 5 pm.

Optionally, step a) may further comprise the step of providing an auxiliary stripe material, preferably a metal material stripe, and the protrusions may be provided in the form of helical coil springs in step a). In step b), the apertures may be formed in an elongated shape, such that

-3through each aperture a wire of a turn of the helical coil springs can be positioned. Step c) may further comprise the sub-step of introducing the auxiliary stripe essentially parallel to the axis of the helical coil spring through the arch bend portions formed by the wire of the helical spring coil on the first side of the auxiliary sheet. In step d) the protrusions, the auxiliary sheet and the auxiliary stripe may be connected, and in step f) the machining of the outwardly oriented portions may be executed such that the helical coil spring is separated into individualized protrusions.

In another option, the protrusions in step a) may be provided in the form of helical coil springs and in step b), the apertures may be formed at a size adapted to allow the wire of the helical coils spring to pass through. Step c) may then be executed such that each one turn of the wire of the helical coil spring is passed through each one aperture of the auxiliary sheet, preferably by introducing the helical coil spring in a rotating movement consecutively though two rows of apertures. In step f) the machining of the outwardly oriented portions is executed such that the helical coil spring is separated into individualized protrusions.

Optionally, the auxiliary sheet and the auxiliary stripe, if present, is a metal sheet, and preferably the step d) of connecting the protrusions to the auxiliary sheet in the apertures and the auxiliary stripe, if present, is executed by welding or soldering.

In another option, the protrusions are provided in step a) in the form of wire meshes of rounded wires, preferably a set of inter-engaged spiral coil wires, forming a net-like structure adapted to be positioned on the surface of a cylindrical roll. Also in step a) the providing the auxiliary sheet material may be by providing the auxiliary sheet material in a formable form, preferably a liquid or semi-liquid form adapted to solidify into a semi-rigid of flexible sheet. Further, in step a) of at least the providing of the auxiliary sheet and steps b), c), and d) are executed simultaneously, by forming the auxiliary sheet in-situ on the roll blank or the auxiliary roll whilst the wire mesh of the protrusion is positioned thereon, such that the auxiliary sheet material encloses portions of the wire mesh or the full wire mesh, and such that the connecting of the protrusions to the auxiliary sheet material is executed by forming the auxiliary sheet from the auxiliary sheet material and form-locking or adhesive connecting. Optionally in step f) of machining the outwardly extending portions of the arch bend flanks or the arch supports to a predetermined precision with regard to the distance to the axis, a portion of the auxiliary sheet material is machined away.

Brief description of the Figures

Fig. 1 A to H show schematically a roll as may be made according to the present invention and outwardly positioned protrusions.

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Fig. 2A and 2B show further details of the roll and the protrusions.

Fig. 3A to 3D show schematically protrusions as inserted and combined with an auxiliary sheet according to a first execution of the process according to the present invention.

Fig. 4 A to I depict protrusions as part of a helical coil spring and the combination with an auxiliary sheet according to a further execution of the present invention.

Fig. 5 A to D depict a further execution for providing protrusions at high precision.

Fig. 6 A to E depict further executions for providing protrusions at a high precision.

Fig. 7 schematically represents the manufacturing process according to the present invention. Same numerals refer to same elements or features. The figures a schematic and not necessarily to scale.

Detailed description

In referring to Fig. 1, the present invention is the manufacturing of a treatment roll 1000 that comprises a plurality of arch-like protrusions 1100 that extend radially away from the rotational axis 1010 of said roll, whereby the distances of the tips of the protrusion from the axis of the roll exhibit only very little variation, thereby allowing very precise treatment of web materials. Such a roll may be used for bonding or embossing or otherwise treating flat or web materials.

In a cylindrical coordinate system 1005, a bonding roll is adapted to rotate around the axis 1010 along the width direction 1 of the system with the angular direction phi, and a radial direction r.

The bonding roll 1000 comprises a plurality of protrusions 1100, preferably in a protrusion pattern, extending generally radially away from the axis 1010 and from a primary surface 1050 of the roll, that may be the outer, preferably high precision surface of a treatment roll blank. The protrusions are adapted to contact a web material and interact therewith, e.g. by the application of a counter pressure, like a surface of a static support or a counter-rotating roll, such that the protrusions penetrate at a predetermined depth into the web material.

Protrusions may be made from a wide choice of materials. The protrusion materials are adapted to withstand the mechanical stress that is created by the interaction of the treatment roll with a web and/or a counteracting surface or roll. Henceforth, protrusions are preferably made of metal, more preferably steel, though other metals or even polymeric material may be employed if they satisfy the strength or temperature requirements of the process for which they are intended to be used. Most preferably, protrusions are made from a wire material, that is separated into individual protrusion material pieces.

Within the present context, protrusions are executed in an arch-like shape. An “arch” or related

-5expressions relate to a rounded structure that spans a certain width and exhibits a certain height.

Thus, an arch 1200 comprises an upper or bend portion 1210 that is rounded in a side view as shown in Fig. IB to ID. The bend portion comprises two bend flanks 1212 and 1218, between which the arch apex point 1219 is positioned.

An arch may comprise support portions 1220’ and 1220”, though segmented arches as shown in Fig. 1C are included, too. An arch may be executed as a horseshoe arch (see Fig. ID) or as any rounded arch like parabolic, elliptic, or catenoidal arch. Preferably, the bend portion exhibits a circular shape.

Within the context of an arch, the terms “upper” and “lower” portions or an arch or protrusion refer to the reference system of the arch, wherein an arch can be generally described by an inverted U with the opening oriented towards the axis of the finished treatment roll opposite of the arch apex point. Even if an arch “is turned upside down” (i.e. like a “normal” U), e.g. during the manufacturing of the treatment roll, the arching or bend portion with the arch apex point will remain the “upper” or tip portion. The “lower” portion of the arch comprises the support portions or - in case of no support portions - the portions of the bend flanks oriented away from the arch apex point.

An arch 1200 may exhibit a length direction, that spans from a first support portion, if present, through the first bend flank to the arch apex point, and further through the second bend flank and the second support portion, if present.

Along this length direction, an arch exhibits a cross-section 1215 that preferably, though not necessarily, is of the same shape throughout this length. It is important that the cross-sectional shape of the arch at least at the arch apex point 1219 is rounded, i.e. tapers down towards the axis of the roll in all three coordinate directions 1, r, and phi. Preferably, the cross-section is circular, Fig. IE, elliptical, Fig. IF, half-circular, Fig. 1G, or-elliptical, bi-tri-, or polygonal, with at least the outermost edge being rounded, Fig 1H. Most preferably the cross-section is circular.

In Fig. 2A and B, further particulars of a treatment roll 1000 and protrusions are explained, with a treatment roll axis 1005, a primary roll surface 1050 and a protrusion 1100 in the shape of an arch 1200 here shown with two support portions 1220, a bend portionl210 and an arch apex point 1219. The protrusion extends at a first height 1120 from a primary surface of the bonding roll which is significantly smaller than the radius 1055 from the axis to the primary surface 1050. The arch apex point 1019 is distanced away from the primary surface at an arch height corresponding to the protrusion height 1120. In the particular, non-limiting execution shown, the protrusion rests on the primary surface, i.e. a protrusion support structure, that may

-6be part of the bonding roll structure, that can be machined to a high precision, i.e. with a very small variation of the radius 1055 along the circumference of the roll.

During use, the present invention aims at providing a treatment roll for which the variation of the distance of the individual apex points of a plurality of protrusions is minimized.

Ideally, all apex point are positioned on a cylindrical surface, but in reality they exhibit certain height variations such that all points are positioned inwardly of a (thought) cylindrical envelope 1020 at a distance 1208 of the outermost arch apex point of the treatment roll to the axis at an envelope radius 1025. With conventional technologies, it has been found difficult to create rounded protrusions, in particular as arches, to a precision as desired for particular treatment steps at a height variation of the protrusions less of than 50 pm, preferably less than 20 pm, more preferably less than 10 pm. and most preferably less than 5 pm, relative to the envelope 1020.

The reason for the imprecision may be variations in the material of which the arches of the protrusions are manufactured, such that material thickness variation, especially at the arch apex point, may contribute to the variations or length variations of the arch support structures as indicated in Fig.2B, where first arch support 1220’ and a second arch support structure 1220” exhibit an arch support structure height difference 1225. If the arch does not comprise support portions, the bend flanks of the bend portions may not have exactly the same dimensions. As a consequence, the arch may be tilted, i.e. the arch axis is not perpendicular to the primary' surface. The variations may be randomly or may exhibit a particular pattern, such as a circumferential bias.

If the arches with their arch apex points positioned outwardly were machined such as on a precision lathe, the variations can be reduced, but at the same time, the arch apex point regions lose their rounded, in all directions tapering shape that is very desirable for certain applications.

Henceforth, the present invention applies precision machining, but not to the arch apex point, but to the arch support, or the lower portion of the arch bend flanks, if no arch support is present.

Thus, the principle of the present invention is to combine a plurality of arch shaped protrusions with an auxiliary sheet with appropriate apertures for receiving parts of the protrusions. The auxiliary sheet provides stability along its x-y-direction, but is flexible in its z- or thickness direction. For certain executions, the auxiliary' sheet is preferably a thin metal sheet, e.g. a steel plate of 1 mm thickness.

In order to further explain this principle, several executions of the present invention are now described in more detail, which should, however, not be seen to limit the present invention to

-7the features described therein, and which may be combined in various options.

A first execution is schematically depicted in Fig. 3A to D, wherein a plurality of arches 1200 are put into apertures 1420 of an auxiliary sheet 1400 such that the arch supports 1220 penetrate through the sheet. If the arch structure has no support structure, the flanks of the bend portion can be put through the apertures. The arches are connected to the auxiliary sheet by a suitable connection 1450, such as welding, soldering, gluing or the like. The support portions of one arch as well as of different arches, or bend flanks in case of the absence of support portions, will now exhibit certain height differences 1208 (see Fig. 2B).

As a next step, the sheet is positioned onto the primary surface of a precisely machined roll, such that the arch apex points are directed “inwardly” towards the axis and the arch supports or flanks of the arch bends are positioned outwardly, see Fig. 3D. Sufficiently high force may be applied in the x-direction of the sheet to ensure that all apex points are in contact with the surface of the roll. The roll may be the treatment roll blank, i.e. same roll to which the protrusions will be applied in a later step to form the treatment roll. Alternatively, the roll in this process step may be an auxiliary precision roll as may be used for machining more than one auxiliary sheets, each of which may be combined with a separate treatment roll blank.

As a next step, the outwardly oriented arch portions are machined to the desired precision, i.e. the distance of each of the end points to the axis is within less than 50 pm, preferably less than 20 pm, more preferably less than 10 pm. and most preferably less than 5 pm. Subsequently, the sheet with the machined arches may be turned “right” such that the machined support portions or bend flanks rest on the primary surface, as shown in Fig. 2A. As a consequence, the auxiliary sheet may deform slightly in its z-direction, but maintain essentially the x-ypositioning of the arches, and the arch apex points are now protruding from the primary surface with the appropriate precision.

Another execution is now described by referring to Fig. 4 A to I, wherein the arches are formed from a helical coil spring.

To this end, as shown in Fig. 4A and the cross-sectional view along BB in Fig. 4B, the support sheet 1400 comprises elongated apertures 1420 through each of which the wire of one turn of the helical coil spring 1250 is put so as to form the arch bend portion 1210 with the arch apex point 1219, as indicated in Fig. 4C and the cross-sectional view Fig. 4D. The lower portions of the spring positioned opposite of the apex point in relation to the auxiliary sheet may be considered support portions, albeit not in a columnar shape but also as bend flanks 1229’ and 1229”, initially spanning from one aperture 1420’ to a neighboring one 1420” (indicated as dashed line in Fig. 4C and in Fig. 4D; the dashed region 1255 indicates the cut-off in the view of two neighboring flights of the spring coil).

-8An auxiliary strip 1500 can now be positioned along the longitudinal axis of the helical coil spring between the auxiliary sheet and the upper arch bend portion as indicated by the arrows in Fig. 4E, thereby closing a portion of the elongated apertures and forming an aperture for each of the arch bend flanks, as further indicated in cross-sectional view Fig. 4F and an enlarged view thereof in Fig.4G.

The wires of the spring may then be connected to the auxiliary sheet and strips such as by soldering, welding, gluing or the like as described in the above at connections 1450, as shown in Fig. 4H.

Subsequently, the auxiliary sheet with the spring is positioned onto the primary surface of a treatment or auxiliary roll, as described in the above, and the now outwardly positioned lower portion of the helical spring is machined away, such that each turn of the spring now forms a separated arch - with bend flanks outwardly of the auxiliary sheet and arch apex points inwardly, see Fig. 41.

Subsequently, the sheet with the machined arches may be turned “right” such that the machined arch bend flanks rest on the primary surface of a treatment roll. As a consequence, the auxiliary sheet may deform slightly in its z-direction, but maintains essentially the x-ypositioning of the arches, and the arch apex points are now protruding from the primary surface with the appropriate precision.

Once positioned on the treatment roll blank, the auxiliary sheet with the precision machined protrusions may be fixed on the roll by conventional means, such as threaded bolts or clamps. A variant of this execution is further explained by referring to Fig. 5A to D. Therein, as shown in Fig. 5A and the cross-sectional view Fig. 5B, the apertures 1420 for receiving the helical coil spring 1250 are formed at a size that is adapted to allow the spring wire to penetrate through. Then this wire of a helical coil spring may be introduced into two parallel rows of apertures 1420’ and 1420”, respectively, of the auxiliary sheet by starting at an end section of the auxiliary sheet and inserting the wire consecutively though the series of apertures. The machining will be performed as described hereinbefore along the machining line as indicated in the cross-sectional view Fig. 5D.

Yet a further execution is described by referring to Fig. 6 A to E. In this execution, the protrusions are provided in the form of wire meshes of rounded wires. In a first variant such wire meshes may be formed from helical coil springs 1250’, 1250”, and 1250’” in Fig. 6A and a cross-sectional view 6B, respectively, as suitable for the previously described executions, which may form the mesh structure by being inter-engagingly combined, wherein the dashed region 1255 indicates the cut-off in the view of two neighboring flights of the spring coil. Alternatively, wire meshes as commercially available e.g. from Schulz Drahttechnik GmbH,

-9Neuhausel, Germany, can be used, that typically exhibit dimensional variations which make them unsuitable as such for the present application. Further, for the present execution, the auxiliary sheet 1400 is not a preformed sheet like a metal sheet but rather is formed in-situ from a formable material, such as a liquid or semi-liquid material adapted to solidify into a semi-rigid or a flexible sheet. A typical material may be a silicone or acrylic rubber material, that can be applied the surface of a cylindrical roll, such as an auxiliary roll, which is adapted so as to allow removal of the flexible sheet such as by surface treatment or a release layer. As indicated in Fig. 6C, the wire mesh is now embedded into the auxiliary sheet material 1400 such that the wires form effectively their own apertures wherein they are connected to the auxiliary sheet material by form locking or adhesion. In one embodiment the wire mesh is not fully immersed, but that at least the arch apex 1219 and neighboring bend flanks 1212 and 1218, respectively, are not embedded. In another embodiment as shown in Fig. 6E, the wire mesh may be fully immersed, such that also the arch apex is embedded, though for various applications it may be advantageous to have the arch apex point free of auxiliary sheet material. After allowing the auxiliary sheet to solidify to provide sufficient structural integrity, the combined auxiliary sheet with the wire mesh may be turned around and machined along a machining line 1270 as described in the above, whereby the individualized, high precision protrusions are made.

Such high precision protrusions rolls may now be used to treat materials such as web materials, such as by embossing or printing these web materials. In a particular application, such rolls may interact with an ultrasonic sonotrode, be this of the stationary or of the rotary type. In an even more particular application, the web treated between the roll and the sonotrode comprises fibers and particulate material positioned in its interstices. Upon rotating and application of the ultrasonic energy and the interaction with the protrusions of the roll, the particles may be slightly dislocated so as to allow ultrasonic bond points which are particle free.

Process lay-out

Referring now to Fig. 7, the process 9000 according to the present invention is depicted in a flow chart.

Protrusion materials are provided (9010) as well as an auxiliary sheet material (9020) into which optionally apertures may be pre-formed (9025). Protrusions are combined with the auxiliary sheet material (9050) either by being fitted into the apertures or by forming the auxiliary sheet in-situ around the protrusion material. Optionally a further auxiliary stripe is provided (9030) and added to the auxiliary sheet with the protrusions. Further, the protrusions are connected to the auxiliary sheet, and - if present - to the auxiliary stripe (9060), e.g. by

-10soldering, welding, gluing or solidifying of the in-situ formed auxiliary sheet material.

The auxiliary sheet with the protrusions and - if present - auxiliary stripe may now be combined with a roll.

The roll is selected (9130) from an auxiliary roll (9120), that may be for the purpose of 5 machining the lower parts of the protrusions only, and a treatment blank roll (9110), that when finished in the present process - may be used to treat web materials. The cylindrical surface of such rolls exhibit preferably a low variation, e.g. by being machined to a high precision of +/- 5 pm or even less than +/- 2 pm.

The combining (9200) is executed such that the upper portion with the apex points of the 10 protrusions are oriented inwardly towards the axis of the roll and contact its surface. The opposite portions may now be machined (9300) to the predetermined precision, such as by lathing, grinding etc.

As the last step of this process 9400, the auxiliary sheet with the protrusions is removed from the roll on which it has been machined, turned around and combined with the treatment roll such that the arches face outwardly. The auxiliary sheet may slightly deform z-directionally, and the arch apex points exhibit only small variations.

Claims

1. A method for manufacturing a high precision treatment roll, said treatment roll exhibiting in cylindrical coordinates a treatment roll width 1, a radius r, and an angular component phi, and comprising a center axis aligned with the roll width around which said roll is rotatably mounted, and a plurality of protrusions extending generally radially outwardly from said roll, each of said protrusions exhibiting an arch-like shape with a bend portion comprising an arch apex point and two arch bend flanks tapering away from said arch apex point and optionally two support portions connected by said bend portion, whereby the arch apex point is positioned radially further away from the center axis relative to the bend portions of the arch or to the support portions, if present, said method comprising the steps of

b) forming apertures in a sheet of said auxiliary sheet material adapted to receive a plurality of said protrusions;

c) positioning portions of said protrusions in said apertures such that a first portion of a protrusion comprising said arch apex point is positioned on a first side of said auxiliary sheet, and portions of said arch bend flanks or arch supports extend through said apertures towards tire opposite side of tire auxiliary sheet;

d) connecting said protrusions to said auxiliary sheet in said apertures;

e) positioning said auxiliary sheet with said arch shaped protrusions on the surface of said treatment roll blank or said auxiliary roll, if present, such that said arch apex points are oriented inwardly towards the roll axis, and portions of said arch bend flanks or arch supports extend

-12outwardly;

f) machining said outwardly extending portions of said arch bend flanks or said arch supports to a predetermined precision with regard to the distance to the axis;

g) re-positioning said auxiliary sheet on said treatment roll blank such that the arch apex points are oriented outwardly and said machined arch bend flanks or arch supports inwardly towards the axis;

h) fixing said repositioned auxiliary sheet on said treatment roll blank, wherein the arch apex points of the plurality of protrusions exhibit a variation of the distance to said roll axis which is less than 20pm, preferably less than 10 pm, more preferably less than 5 pm.

2. A method according to claim 1, wherein said step a) further comprises the step of providing an auxiliary stripe material, preferably a metal stripe material;

in step a) said protrusions are provided in the form of helical coil springs;

in step b) said apertures are being formed in an elongated shape such that through each aperture a wire of a turn of said helical coil springs can be positioned; said step c) further comprises the sub-step of introducing said auxiliary stripe material essentially parallel to the axis of said helical coil spring through said arch bend portions formed by said wire of said helical spring coil on the first side of said auxiliary sheet;

wherein in step d) said protrusions, said auxiliary sheet and said auxiliary stripe material are connected, and wherein step f) of machining the outwardly oriented portions is executed such that the helical coil spring is separated into individualized protrusions.

3. A method according to claim 1, wherein in step a) said protrusions are provided in the fonn of helical coil springs;

in step b) said apertures are being formed at a size adapted to allow the wire of said helical coils spring to pass through;

said step c) is executed such that each one turn of the wire of the helical coil spring is passed through each one aperture of said auxiliary sheet, preferably by introducing the helical coil

-13spring in a rotating movement consecutively though two rows of apertures; and wherein step f) of machining the outwardly oriented portions is executed such that the helical coil spring is separated into individualized protrusions.

4. A method according to any of claims 1 to 3, wherein said auxiliary sheet is a metal sheet, and wherein preferably said step d) of connecting said protrusions to said auxiliary sheet in said apertures is executed by welding or soldering.

5. A method according to claim 1, wherein in step a) said protrusions are provided in the form of wire meshes of rounded wires, preferably a set of inter-engaged spiral coil wires, forming a net-like structure adapted to be positioned on the surface of a cylindrical roll; and in step a) said providing said auxiliary sheet material is by providing said auxiliary sheet material in a formable form, preferably a liquid or semi-liquid form adapted to solidify into a semi-rigid of flexible sheet; and further in step a) at least the providing of the auxiliary sheet and steps b), c), and d) are executed simultaneously, by forming said auxiliary sheet in-situ on said roll blank or said auxiliary roll whilst said wire mesh of said protrusion is positioned thereon, such that said auxiliary sheet material encloses portions of said wire mesh or the full wire mesh, and such that said connecting of said protrusions to said auxiliary sheet material is executed by forming said auxiliary sheet from said auxiliary sheet material and form-locking or adhesive connecting, and that optionally in step f) of machining said outwardly extending portions of said arch bend flanks or said arch supports to a predetermined precision with regard to the distance to the axis, a portion of said auxiliary sheet material is machined away.

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Application No: Claims searched:

GB1618732.0

1-5