WO1995018012A1

WO1995018012A1 - Embossing device

Info

Publication number: WO1995018012A1
Application number: PCT/DE1994/001555
Authority: WO
Inventors: Kai KÄHLER
Original assignee: Detroit Holding Limited
Priority date: 1993-12-30
Filing date: 1994-12-30
Publication date: 1995-07-06
Also published as: DE4345128A1; AU1381095A

Abstract

Described is a device for forming indentations and/or protuberances at given intervals in the plane of a continuous strip of low-rigidity material (1) running through the device, using embossing cylinders (2, 3) each having a rotating support tube (4, 5) and at least one embossing die (2a to 2e, 3d, 3e) with a diameter significantly greater than that of the support tube (4, 5). The embossing die has a core (21e, 31e), made of high-rigidity material, which is rigidly mounted on the support tube concentric with the support tube. Rigidly joined to the surface of the cylinder core is a structured layer (22e, 32e) with a rigidity lower than that of the core and with a thickness which is at least equal to the maximum embossing depth.

Description

Embossing device

Description

The invention relates to a device of the type specified in the preamble of claim 1 and a method for producing this device.

Devices for embossing web-shaped - in the sense of quasi-endless - material are available in a variety of designs. known from the printing and packaging industry, the processing of plastic films and other areas of technology.

Devices of this type usually have rollers with a profiled surface, between which the sheet-like material to be processed - paper, cardboard, plastic films etc. - runs and which press their surface profile into the material. Mostly steel rollers are used, especially with chrome plating.

From DE 32 02 914 AI a longitudinal cutting and creasing machine for the packaging industry is known, in which individual embossing and / or cutting tools are clamped in a row in the axial direction on a rotatable sliding tube, which creases and cuts in the packaging material to be processed produce.

The publication DE 41 25 996 Cl describes a heatable embossing roller with segments arranged next to one another for processing plastic films.

From DE 39 15 508 AI a machine for pressure treatment of webs is known, which has a roller with individual ceramic rings lying next to each other in the axial direction as embossing tools.

These known devices with embossing tools made of very hard material enable the processing of conventional, relatively strong packaging materials with little tool wear, and the tools, because of their considerable rotationally symmetrical shape can be produced with reasonable effort despite the hardness of the material.

If, however, recesses and / or elevations of relatively great height are to be formed in materials of low strength - such as non-woven material, filter paper or foam film webs - there is a risk of damage to the material, such as so-called embossments, when using devices of this type with very hard tools. If, in particular, embossing structures are to be produced which require the embossing tools to be shaped substantially differently from the rotationally symmetrical shape, their manufacture from the customary, highly wear-resistant materials also becomes very complex.

The invention is therefore based on the object of specifying a device of the type mentioned at the outset which is suitable and inexpensive to produce for processing low-strength materials, in particular filter nonwovens, and a method for producing this device.

This object is achieved by a device with the features of claim 1 and a method with the features of claim 10.

The invention includes the knowledge that, on the one hand, to produce depressions and / or elevations of greater height in sheet-like materials of low strength, to avoid damage to the material to be processed, and to guarantee acceptable tool costs (in the as is well known, production costs and life expectancy), on the other hand, tools with a well-defined radial strength profile are to be provided.

This radial strength profile should be selected so that the tool has a relatively low hardness or strength from the outer circumference to at least approximately the maximum embossing depth, but then this increases sharply radially inwards. The strength in the edge area must be selected in accordance with the material to be machined so that precisely shaped, permanent recesses or elevations are formed and tool wear is limited. The shape and strength of the tool in the inner area (the tool core) must be so high that the tool as a whole remains stable in the embossing process even after prolonged use.

A preferred embodiment is that the core has the shape of a hollow cylinder. By choosing a rotationally symmetrical core, good concentricity of the embossing roller is advantageously achieved. A rotationally symmetrical (cylindrical or hollow cylindrical) core can also be manufactured easily and inexpensively.

In an alternative embodiment to this, the circumferential surface of the core can be profiled, ie the shape of the depressions and / or elevations to be formed in the material to be machined can be predetermined entirely or partially in the shape of the core. In this case, the layer of lower strength can additionally have areas of different thickness and thus the profiling of the core - picking them up - reinforcing them. However, it can also be applied as a (damping) layer of constant thickness.

In the investigations carried out, it has been found to be advantageous if the average thickness of the profiled layer is at most 1/20 of the average diameter of the embossing tool.

An embodiment of considerable practical importance in the production of packaging material or filter inserts for fluid filters is one in which the profiled layer has cam-like elevations and / or depressions arranged non-rotationally symmetrically for impressing complementary depressions and / or elevations in has the sheet material.

In preferred embodiments of the device according to the invention, the core consists of metal, in particular aluminum, brass or steel, and the profiled layer of plastic, in particular a polyurethane material.

In a device for embossing a plurality of patterns parallel to one another in the longitudinal direction of the web into the web-shaped material, a plurality of embossing tools are advantageously arranged next to one another on the support tube, the cores having essentially the same diameter and the profiled layers essentially the same thickness to have.

The profiled layer can consist, for example, of a strip of the material of lower strength which is glued to the core. A preferred embodiment consists in that the profiled layer is cast or injection-molded onto the core in a casting or injection mold.

This method specified in claim 10 can be carried out particularly elegantly if a polyurethane material is used as the plastic to obtain the profiled jacket shape. Its strength can easily be adjusted to the conditions of the specific embossing process to be carried out with the tools produced by suitable selection and mixing of the monomers and, if appropriate, fillers.

Alternatively, an epoxy resin material can be used as the plastic to obtain the profiled shell shape.

The original mold used in the claimed process can preferably be produced from aluminum, which can be comparatively easily brought into the required, complicated shape.

The claimed device represents a stamping device that can be provided quickly and cost-effectively, in particular for forming stampings with the highest precision in relatively soft materials that cannot be produced by rotationally symmetrical roller profiles. Such embossings are required, for example, in filter manufacture.

The claimed method, which takes up and implements the construction principle of the device in terms of process technology, represents an efficient and inexpensive manufacturing process.

Advantageous developments of the invention are characterized in the subclaims or are shown in more detail below together with the description of the preferred embodiment of the invention with reference to the figures. Show it:

FIG. 1 shows a schematic perspective illustration of an embodiment of the device according to the invention,

2a and 2b are schematic cross-sectional representations of an embossing roller in two embodiments and

Figure 3 is a schematic diagram of the method for manufacturing the device.

1 schematically shows how a web 1 made of plastic foam material, which is to be provided with a number of different embossing patterns, passes between two embossing rollers 2 and 3, which are each fixed to a hollow shaft 4 or 5, and with this in the direction of rotation indicated by the curved arrows.

The embossing rollers are shown in the figure from various embossing rings or segments which are axially pushed onto the shaft 4 or 5 and are rotatably held on the latter by means of tongue and groove, with only the upper embossing shaft 2 being shown in FIG. 1 for the sake of clarity all five rings 2a to 2e, from the lower one, through the leaking material web largely covered, embossing shaft 3, however, only the rings 3d and 3e are shown. (In practice, the ratio of the width to the diameter of the rings can deviate considerably from the illustration given, and they do not have to be lined up in a row.)

All rings or segments are - what is shown in the figure with the reference numerals 21e and 22e or 31e and 32e only for the rings 2e and 3e - made of a hollow cylindrical aluminum core and one on its outer surface, surrounding it, cast-on polyurethane jacket.

In order to clarify the range of use, the figure shows a configuration in which all rings 2a to 2e produce different embossed patterns in the material web 1, which runs out of the device as an embossed web 1 '. (In practice, such an embossing roller is not used, but generally the same, periodically repeating pattern is provided over the entire width.) These are from left to right: a fine, irregularly corrugated groove, a raised one , continuous bead, a recessed, continuous bead, hemispherical impressions and prismatic impressions. The rings of the lower embossing shaft 3 each have an embossing contour complementary to the rings of the upper embossing shaft 2 in or on the PU jacket.

In a modified embodiment, in particular if the embossing pattern has only a small depth and should only be present on one surface of the web - the lower embossing shaft should also be smooth.

On the other hand, the contours of the segments can also be considerably higher in relation to the thickness of the material web to be processed, so that the embossed elevations and depressions are much more pronounced and have regular walls.

2a and 2b show two embossing rollers of the type shown in FIG. 1, each in a special embodiment of the core-shell composite, in cross section.

In the embossing shaft according to FIG. 2a, the ring 20a pushed onto a hollow cylindrical shaft or a displacement tube 40 and held there in a rotationally fixed manner with a tongue-and-groove connection 41 consists of a rotationally symmetrical steel disc 201a with a cast PU Jacket 202 with a non-rotationally symmetrical embossing contour 202a, which is formed in its entire height from the PU material.

2b shows an embossing shaft with a similar embossing contour, in which a ring 20b held on the shaft 40 by means of the tongue and groove connection 41 is made of a non-rotationally symmetrical brass disk 201b, into which the course of the embossing contour is incorporated, and one on the same Is circumferentially glued on plastic strips 202b of constant thickness.

FIG. 3 shows the method for producing a device using the structure shown in FIGS. 1 and 2a illustrated with a flow chart of the most important process steps.

First, the required embossing contour of the tool is calculated on the basis of the desired surface profile la of a material web 1 to be embossed with the aid of a computer R.

The calculated surface profile is converted into an aluminum master form U of the embossing tool by means of a numerically controlled machine tool NC.

On the basis of the smallest radial dimension of the original shape and taking into account the strength properties of the material to be processed on the one hand and the materials provided for the embossing tool on the other hand - again with the help of the computer R - the optimal diameter of the core 201a of the tool (embossing ring) 20a to be produced is determined , this is produced on a lathe D and provided with the groove for the tongue and groove connection.

With the help of an internal lathe ID, a permanent form frame FR with a cylindrical recess is produced in accordance with the greatest radial extent (with an addition calculated with the aid of the computer R) and the height of the original form u - again made of aluminum.

In these, the original form U is concentrically inserted with a release agent and the space between the frame FR and the original form U is poured out with plastic. After removal of the original form, the form F for producing the embossing rings is formed in this way. The core 210a is inserted into the mold F after it has been provided with a release agent, the intermediate space is filled with a urethane mixture and the latter is polymerized, the shell 202a which is firmly connected to the core and carrying the embossing contour and the embossing together with the core ¬ forms ring 2a, which is pushed onto the shaft 40 and fastened by means of the tongue and groove connection.

The embodiment of the invention is not limited to the preferred embodiment described above. Rather, a number of variants are conceivable which make use of the solution shown, even in the case of fundamentally different types.

In particular, materials other than those specified can be used to achieve the required strength profile; this also applies to the molding materials. The embossed profiles shown and the materials mentioned as goods to be processed are also to be understood as examples only.

* * * * *

Claims

Expectations

1. Device for embossing depressions and / or elevations arranged in the plane with a predetermined periodicity in sheet-like, continuous material (1) of low strength with an embossing roller (2, 3) with a rotatable support tube (4, 5 ; 40) and at least one embossing tool (2a to 2e, 3d, 3e; 20a, 20b) arranged thereon with a much larger diameter than the support tube (4, 5; 40), the embossing tool having a core ( 21e, 31e; 201a, 201b) made of a material of high strength,

d a d u r c h g e k e n n z e i c h n e t that

a profiled layer (22e, 32e; 202a, 202b) with a lower strength than the cylinder, the thickness of which is at least equal to the maximum embossing depth, is arranged on the outer surface of the core, connected to it in a rotationally fixed manner.

2. Device according to claim 1, d a d u r c h g e - k e n n z e i c h n e t that the core has the shape of a hollow cylinder (21e, 31e; 201a).

3. Device according to claim 1, dadurchge - indicates that the peripheral surface of the core (201b) is profiled.

4. Device according to one of the preceding claims, that the average thickness of the profiled layer (22e, 32e; 202a, 202b) is at most 1/20 of the average diameter of the embossing tool.

5. Device according to one of the preceding claims, that the profile layer (22e; 202a) has non-rotationally symmetrical, cam-like elevations and / or depressions for impressing corresponding depressions and / or elevations in the web-like material.

6. Device according to one of the preceding claims, characterized in that the core (21e, 31e; 201a, 201b) made of metal, in particular aluminum, brass or steel, and the profiled layer (22e, 32e; 202a, 202a) made of plastic, in particular a polyurethane material.

7. Device according to one of the preceding claims, d a d u r c h 'g e k e n n z e i c h n e t that on the support tube (4, 5) a plurality of embossing tools (2a to 2e, 3d, 3e) are arranged side by side, the cores of which have essentially the same diameter.

8. Device according to one of the preceding claims, characterized in that the profiled layer (202b) is glued to the core (201b).

9. Device according to one of the preceding claims, d a d u r c h g e k e n n z e i c h n e t that the profiled layer (202a) on the core (201a) is cast or injection molded.

10. A method for producing a device according to one of the preceding claims, comprising the steps:

- Production of a metal master form (U) of the embossing tool (20a) in accordance with a surface profile of the web-like material (1) to be generated,

- Manufacture of a circular cylinder (201a) with a minimal thickness of the profiled layer (202a) to be arranged on the circular cylinder compared to the smallest radial dimension of the metal master mold (U) and a central recess corresponding to the cross-sectional shape of the support tube (40) ,

Producing a metal permanent mold frame (FR) with the height of the circular cylinder (201a) corresponding to a height and a circular cylindrical interior with the largest radial extent of the original form (U) slightly exceeding diameter,

- concentric insertion of the master mold (U) as the primary mold core in the interior of the permanent mold frame (FR),

- Filling the space between the primary mold core (U) and permanent mold frame (FR) with plastic and curing it to obtain a profiled shell shape (F), Removal of the original shape (U) and insertion of the circular cylinder (201a) as a secondary mold core into the shell shape (F),

- Filling the space between the secondary mold core (201a) and the shell mold (F) with the material of the profiled layer (202a) to be formed and curing the material and

- Remove the finished embossing tool (20a) from the jacket shape (F) and push it onto the support tube (40).

11. The method according to claim 10, d a d u r c h g e ¬ k e n n z e i c h n e t that a polyurethane material is used as the plastic to form the inner shell region of the profiled shell shape (F).

12. The method of claim 10, d a d u r c h g e - k e n n z e i c h n e t that an epoxy resin material is used as the plastic to form the inner shell region of the profiled shell shape (F).

13. The method according to any one of claims 10 to 12, d a - d u r c h g e k e n n z e i c h n e t that aluminum is used as the metal for the production of the original form (U) and / or the Mantelformrah¬ frame (FR).

* * * * *