EP0955157A2 - Stamping tool and method for chemically and/or physically binding or stamping one or more layers of web-shaped materials - Google Patents

Abstract

The embossment surfaces (34,35,36,37), at least partly with different spacing, run at specific angles to a reference line (38,39) or to a reference surface of the embossment mould. The embossment moulds are cylinders, which in operation run opposed to each other, and the reference line is the actual rotary axis of the cylinders.

Description

The invention relates to an embossing tool for chemical and / or physical connection or embossing of one or more layers of sheet-like materials, with two embossing dies that are at least opposite one another on a contact line, on which embossing points and / or embossing surfaces are arranged, which are at least along the contact line of the embossing dies partially overlap. The invention further relates to a method for producing an embossing mold for such an embossing tool and the use of an embossing mold as a master mold for a counter mold. A method for producing chemically and / or physically bonded or embossed layers of sheet-like materials is also described.

A web-like material consisting of several layers is conventionally bonded by placing the layers between two rollers, at least one of which introduces the impressions into the web-shaped material, these impressions generally being provided by positive locking, but also by chemical-physical measures. Connection points are established. The resulting web-like material can then optionally be further processed, for example cut to the known hygiene tissue.

In the embossing process, a distinction is made between game embossing, in which an embossing roller runs against a smooth counter-roller, which may have an elastic coating. With the Union embossing, a die roller and a male roller run against each other and create a connection of the web-shaped materials through the resulting embossing. In both wild and union embossing, the fine embossments on one side of the web-shaped material are concave inwards and protrude convexly on the other side. These convex raised areas give the embossed material a rough character and should therefore be avoided.

FIG. 7 shows a sectional view through a cellulose cloth which consists of four webs 14, 15, 16 and 17, which are formed between an embossing roller and a counter-roller on embossments 19, 19 'by the wild embossing process get connected. The axes of rotation of the embossing roller and the counter roller are designated by the reference numbers 25 and 26, respectively. The web intake, which is caused by the different flow path of the webs 14, 15, 16 and 17, is shown with the dimension arrow 18 or 18 '. The different web feed results from a longer path of the web from web 17 to web 14. The points 19 and 19 'connected by the embossing lie deeper than the raised surface 20 and higher than the surface 20' of the cellulose cloth. The raised embossing surfaces 21 and 22 or the opposing surfaces 23 and 24 each lie in a plane parallel to the axes 25 and 26 of the rollers.

The problem of the concave raised embossing points is solved in the head-to-head embossing process disclosed in DE 94 06 026 U1 in that raised embossing knobs are formed on the opposing embossing rollers, which are arranged on the layers of a cellulose cloth, for example, as shown in FIG , form concavely inwardly curved connection points 7 and 7 'which are aligned with one another transversely to the position direction. In the bottom areas of these embossing points 7 and 7 ', the layers 1, 2, 3, 4 of the web-like material are connected to one another by the embossing effect. This process gives the sheet material a smooth appearance on both sides. However, the problem of the different flow paths between the individual layers still persists, as indicated by the dimensional arrows 5 and 5 'for the webs 1 and 2 in the cellulose cloth shown in FIG. 8, for example. The points 7 and 7 'connected by the embossing lie deeper than the raised surface of the cellulose cloth 6 and 6'. The raised embossing points 8 and 9 and 10 respectively and 11 each lie in a plane parallel to the embossing mold axes 12 and 13.

In all of the methods listed, the embossing surfaces of the individual embossing molds lie in a plane parallel to the axis of rotation when working with cylindrical embossing tools, since only for such designs can machining be carried out on commercially available cylindrical grinding machines, in which the cutting tools move past a rotating embossing cylinder. As a result, the optical design of the surface structure of the web-like material is severely restricted.

It is the object of the present invention to provide an embossing tool for connecting and / or embossing layers of sheet-like material, with which a diverse design of the surfaces of the material should be possible while the layers are held together securely.

This object is achieved by the stamping tool according to claim 1. Advantageous refinements are the subject of the dependent claims. A method for producing an embossing mold in such an embossing tool is specified in claim 8. Claim 11 describes the use of an embossing mold as the original form, and a method for producing chemically and / or physically bonded layers of web-shaped materials with an embossing tool according to the invention is presented in Claim 12.

According to the invention, it is provided in an embossing tool that the embossing surfaces are at least partially at different distances and / or at certain angles to a reference line or a reference surface of the embossing molds are arranged progressively. The individual embossing surfaces are therefore not necessarily in a surface symmetrical to the embossing mold axis, since there is no need for machining on commercially available cylindrical grinding machines. Embossing surfaces that are not in one plane at an equidistant distance from the embossing mold axis have different circumferential speeds with the same angular velocity of the embossing surfaces, which can offer advantages if the different friction between the embossing surface and the material to be embossed and the opposing embossing surface is to be used. This result corresponds approximately to that of cold welding.

According to an advantageous embodiment, it is provided that the size, shape, position and distance of the embossing points or embossing surfaces is selected so that the load on each contact line is essentially constant. This procedure can make processes such as counter-bending, creating a bomb, etc. superfluous.

Embossing molds can further advantageously consist of a combination of different materials; in particular, in at least one of the embossing molds, a coating of the thermoplastic material containing the embossing surfaces and having an adhesion promoter layer made of an elastomer can be applied to a steel core. The flow behavior of the materials to be embossed between the embossing dies can be influenced by adding fillers to the elastomeric, thermoplastic or thermosetting materials. In the case of web-shaped materials that are to be embossed, but show a very elastic behavior and are therefore basically difficult to emboss, a filler can be used in the embossing mold in the elastomer plastic of the embossing surface be added, which is expandable and, for example, changes the geometric structure after a master molding process. This includes blowing agents that are stimulated by heat during or after crosslinking. This means that the material to be embossed can only flow in certain areas and thus experiences a permanent, high plastic deformation. The same effect can be achieved by appropriate shaping of the embossing molds, in that pinch edges are provided which partially allow the flow process or partially prevent it.

• a) Bereitstellen eines Rohlings für die Prägeform;
• b) Aufbringen einer ätzfesten Beschichtung auf den Rohling und Abätzen der Beschichtung entsprechend einem Prägeflächenmuster in einer ersten Ebene symmetrisch um eine Referenzlinie oder parallel zu einer Referenzfläche des Rohlings;
• c) volumenmäßiges Abtragen des Rohlings bis in eine zweite Ebene;
• d) zumindest teilweises Entfernen der ätzfesten Beschichtung und gegebenenfalls Neuauftragen einer ätzfesten Schicht entsprechend einem Prägeflächenmuster in der zweiten Ebene;
• e) gegebenenfalls Wiederholen der Schritte c) und d) für eine dritte bis n-te Ebene.

A method for producing an embossing mold for an embossing tool according to the present invention has the following steps:

• a) providing a blank for the embossing mold;
• b) applying an etch-resistant coating to the blank and etching off the coating according to an embossing surface pattern in a first plane symmetrically about a reference line or parallel to a reference surface of the blank;
• c) volume removal of the blank to a second level;
• d) at least partially removing the etch-resistant coating and optionally reapplying an etch-resistant layer in accordance with an embossed surface pattern in the second plane;
• e) optionally repeating steps c) and d) for a third to nth level.

In step c), a laser is used for direct structuring, by etching in a liquid bath or by removal from the ionized state.

In order to utilize the full variability of the method according to the invention, it is provided to treat the surface of the blank in a subsequent step f) by direct structuring in order to produce the embossing surfaces running at certain angles to the reference line or reference surface. In this case, direct structuring should be understood to mean direct structuring using lasers or also direct structuring using cutting tools.

An embossing mold produced according to the above-described method can be used as a master mold for a counter mold, the counter mold having a master mold surface, for example made of a non-hardened polymer or thermoplastic made thermoplastic, which is molded according to the surface structure of the stamp mold, whereby if necessary, the consolidated surface of the counterform is processed further.

With an embossing tool that is constructed in accordance with the present invention, a three-dimensionally shaped embossing is possible for the first time in the area of the opposing embossing surfaces, since the embossing surfaces do not have to be present on the embossing molds in one plane parallel to the embossing tool axis.

In a method for producing chemically and / or physically bound layers of sheet-like materials, layers of the same or different materials can be used. For example, thermoplastic foils, metal foils, etc. can be stamped together.

It is advantageous if, in an embossing tool equipped with counter-rotating embossing rollers, the cylinders are rotated at the same angular velocity. This results in different peripheral speeds at the same angular speed with respect to the axes of rotation, so that friction welding is possible.

A single layer, for example of a thermoplastic material, can also be embossed.

Combinations of different manufacturing processes can be used for producing the embossing tools for an embossing mold and a counter mold, such as direct structuring-direct structuring; Direct structuring primary molding process, removal from the ionized state primary molding process. Different materials are also possible for the embossing mold and for the counter-mold, for example molds can be opposed to one another, both of which are made of metal or both of a suitable plastic, or one is made of metal and the other is made of plastic.

All known methods can be used to apply the various surfaces or layers to a blank for producing an embossing mold. The preferred processes include, in particular, spraying processes, thermal spraying, fluidized bed sintering, vulcanization of rubber, pouring or the application of Heat shrink tubing etc.

All known methods can also be used for structuring the embossing mold or the sleeve. These include, in particular, the area and / or depth-variable laser direct structuring, removal from the ionized state or mechanical engraving.

All methods for applying surfaces or layers and for structuring can be selected as desired depending on the application and can also be used in combination.

Figur 1

eine schematische Schnitt-Teildarstellung von vier Lagen für Hygiene-Zellstofftücher während der Prägung in einem Prägewerkzeug gemäß der vorliegenden Erfindung;

Figur 2a

ein Prägewerkzeug, bei dem ein elastomerer Werkstoff eingesetzt ist, welcher einen expandierbaren Füllstoff enthält;

Figur 2b

ein Prägewerkzeug, bei dem ein elastomerer Werkstoff eingesetzt wird, der Quetschkanten aufweist;

Figur 3

die Abfolge bei einem Verfahren zum Herstellen einer Prägeform für ein Prägewerkzeug gemäß der vorliegenden Erfindung;

Figur 4a, Figur 4b und Figur 4c

ein Verfahren zum Herstellen einer Prägeform im Urformverfahren mit anschließender Laserung;

Figur 5

einen Schichtaufbau für die Prägeform;

Figur 6

einen Schnitt durch eine Prägeform für ein Prägewerkzeug gemäß der vorliegenden Erfindung, bei der der spätere Biegeverlauf schon bei der Herstellung der Prägeform berücksichtigt ist;

Figur 7

vier Lagen für Hygiene-Zellstofftücher zwischen Prägewalzen für die Wildprägung eines Zellstofftuchs; und

Figur 8

vier Lagen von Bahnen zwischen Prägewalzen zum Herstellen von Hygiene-Zellstofftüchern mittels der Kopf-auf-Kopf-Prägung.

The invention will be described in more detail below with reference to the drawings. It shows:

Figure 1

is a partial schematic sectional view of four layers for hygienic cellulose wipes during embossing in an embossing tool according to the present invention;

Figure 2a

an embossing tool in which an elastomeric material is used which contains an expandable filler;

Figure 2b

an embossing tool, in which an elastomeric material is used which has pinch edges;

Figure 3

the sequence in a method of manufacturing an embossing die for an embossing tool according to the present invention;

Figure 4a, Figure 4b and Figure 4c

a method for producing an embossing mold in the master molding process with subsequent lasering;

Figure 5

a layer structure for the embossing mold;

Figure 6

a section through an embossing mold for an embossing tool according to the present invention, in which the later course of bending is already taken into account in the manufacture of the embossing mold;

Figure 7

four layers for hygiene tissue between embossing rollers for the wild embossing of a tissue; and

Figure 8

four layers of webs between embossing rollers for the production of hygiene tissue by means of the head-to-head embossing.

FIG. 1 shows in a partial sectional view how hygiene cellulose wipes are produced from four layers 27, 28, 29 and 30 by means of an embossing tool according to the present invention. The web intake, which is caused by the different flow path of the individual webs, is marked with the dimension arrow 31 or 31 '. The different web feed originates from a longer flow path of webs 30 and 27. The point 32 connected by embossing lies deeper than the raised surfaces 27 or 30 of the cellulose cloth. The point 33 connected by the embossing lies deeper than the surfaces 27 or 30 of the cellulose cloth. The raised embossing surfaces 34 and 35 or 36 and 37 do not necessarily lie in one plane and parallel to the embossing mold axes 38 and 39.

FIG. 2a shows an embossing mold with an elastic coating 40, in which an expandable filler 41 is embedded, which can be expanded after the shape has been produced, for example by means of an original molding process or sublimation. The subsequent expansion causes a jamming at position 42 for the layer 43 to be embossed and thus enables the web-shaped material to flow without the layers being able to flow outwards. This results in a lower web feed 44 and 44 '. There is also a permanent, plastic deformation, which is difficult to achieve with known measures, particularly in the case of very elastic sheet-like materials. Expanding powders are known, for example, from the production of thermoplastic injection molded parts.

FIG. 2b shows an embossing mold with an elastic coating 45, which is provided with pinch edges 46. The crimped edges 46 cause jamming at the point 47 of the layer 48 to be embossed, so that the material can flow without the layer flowing outwards during the embossing. Since the material flows only between the crimped edges 46, this leads to a smaller web feed 49 or 49 '. This results in a permanent, plastic deformation, even for very elastic layer materials.

FIG. 3 shows an example of possible steps in a method for producing an embossing mold for an embossing tool according to the present invention. An embossing die blank 50 first receives an etch-resistant coating 51, which is then at the locations to be etched through in terms of volume 52 is removed, for example, by means of a laser. After the first etching process, a relief is created, as shown for example in partial image 3b). The etch-resistant layer at point 53 is now removed, and volume is removed again, so that a first step formation occurs, as shown in FIG. 3c). If the etch-resistant layer 54 is now removed and then removed in terms of volume, a further step is obtained, as shown in FIG. 3d). Analogously to this, different step configurations can also be achieved in the depressions by re-coating the embossing die blank, FIG. 3e), the etching protection is partially removed and the volume removed again. The step formation can be seen in FIG. 3f) at position 55. Layers that represent a passivating surface can also be removed with the aid of a laser, so that deeper structures can be produced than in conventional etching processes. This is especially true for high-alloy and hardened steels, since the passivation layer is formed during the etching, whereby mainly alloying elements are deposited on the surface to be etched.

FIG. 4 shows, in a partial sectional view, an embossing roller 56, with the aid of which a counterform 57 is produced in the master molding process. For this purpose, the counter mold 57 has a surface which is archable and consists, for example, of uncured polymer or thermoplastics which have been thermoformed. The embossing roller 56 already has the structure to be molded, which has been produced, for example, by direct structuring using a laser or removal from the ionized state. The structure of the embossing roller 56 is shaped by the countermold 57 by means of a counter-rotating movement of the individual embossing molds uni their axes 58 and 59. After the molding and curing or consolidation of the embossing surface 60, the surface of the counter mold 57 can be processed further by removing disruptive material 61 from the surface, so that the finished embossing surface 62 is formed.

FIG. 5 shows an embossing mold in which several materials are combined. For example, an elastomer can be used as an adhesion promoter layer 71 between a thermoplastic 72 and a core 70 made of steel. With the aid of the elastomeric phase, shrinkage stresses which arise due to different coefficients of thermal expansion during the structuring of the layer 72 can also be compensated for. Shrinkage stresses also occur during operation and can also be compensated for. This avoids mechanical damage during operation.

FIG. 6 shows how the subsequent bending curve is already taken into account when the embossing surfaces are at a distance from the embossing die axis when the embossing dies are being produced. The distances 73, 74, 75 of the embossing surfaces to the respective embossing mold axis are adapted, as can also be seen in FIG. 5, such that the surface pressure can be the same in the embossing between all opposing embossing surfaces which act on the sheet-like materials . This procedure can make processes such as counter-bending, creating a bomb, etc. superfluous. Furthermore, a wide variety of motifs can be applied to the cylinder as desired, for example by turning, without problems with different surface pressures along the line of contact of the two embossing dies, between which the layers of web-shaped material lie. surrender.

The features of the invention disclosed in the above description, in the drawing and in the claims can be essential for realizing the invention both individually and in any combination.

Claims (17)

Embossing tool for the chemical and / or physical connection or embossing of one or more layers of sheet-like materials, with two embossing dies facing each other at least on one contact line, on which embossing points and / or embossing surfaces are arranged, which at least partially overlap at least along the contact line of the embossing dies,
characterized in that the embossing surfaces (34, 35, 36, 37) are arranged at least partially at different distances and / or at certain angles to a reference line (38, 39) or a reference surface of the embossing mold. Embossing tool train according to Claim 1, characterized in that the embossing dies are cylinders which rotate in opposite directions during operation, and in that the reference line is the respective axis of rotation of the cylinders. Embossing tool according to Claim 1 or 2, characterized in that the size, shape and position of the embossing points or embossing surfaces and their distance from the reference line or reference surface are selected such that the load on each contact line is essentially constant. Embossing tool according to one of Claims 1 to 3, characterized in that at least one of the embossing dies consists of a combination of different materials (70, 71, 72). Embossing tool according to Claim 4, characterized in that in at least one of the embossing molds, a coating (72) made of a thermoplastic material and having an adhesion promoter layer (71) made of an elastomer is applied to a steel core (70). Embossing tool according to one of Claims 1 to 5, characterized in that pinch edges (46) are provided on the embossing dies for the targeted, partial admission or prevention of the flow of the sheet-like materials. Embossing tool according to one of Claims 1 to 6, characterized in that at least one of the embossing dies is provided with an elastic coating (40) which contains an expandable filler (41). Method for producing an embossing mold for an embossing tool according to one of claims 1 to 7, comprising the steps: a) providing a blank (50) for the embossing die; b) applying an etch-resistant coating (51) to the blank (50) and removing the coating according to an embossing surface pattern (52) in a first plane symmetrically about a reference line or parallel to a reference surface of the blank (50); c) volume removal of the blank (50) up to a second level; d) at least partially removing the etch-resistant coating (53) and optionally reapplying an etch-resistant layer according to an embossed surface pattern in the second plane; e) optionally repeating steps c) and d) for a third to nth level. A method according to claim 8, characterized in that at least one additional coating is subsequently applied to the embossing tool. A method according to claim 8 or 9, characterized in that the coatings (51, 53) are applied by spraying, thermal spraying, fluidized bed sintering, vulcanization of rubber, pouring or by attaching shrink sleeves. Method according to one of Claims 8 to 10, characterized in that the removal in step c) is carried out by means of a laser for direct structuring which is variable in area and / or depth, by etching in a liquid bath, by removal from the ionized state or by means of mechanical engraving. Method according to one of claims 8 to 11, characterized in that f) the surface of the blank (50) is treated by direct structuring to produce the embossing surfaces which run at certain angles to the reference line or retrial surface. A method according to claim 12, characterized in that the direct structuring is carried out variable in area and / or depth by means of a laser or by mechanical engraving. Use of an embossing mold produced, for example, according to one of claims 8 to 13 as a master mold for a counter mold, the counter mold (57) having a master mold surface, e.g. made of uncured polymer or thermoplastic made thermoformable, which is molded according to the surface structure of the embossing mold (56), the consolidated surface of the counter mold (57) being further processed if necessary. Method for producing chemically and / or physically bonded or embossed layers of sheet-like materials with an embossing tool according to one of claims 1 to 7, in which layers of the same or different Materials are used. Method according to claim 15, with an embossing tool according to claim 2, in which the cylinders are rotated at the same angular velocity. The method of claim 15 or 16, wherein a layer of thermoplastic material is embossed.

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