WO1998045100A1

WO1998045100A1 - An apparatus and a method for impressing a relief pattern in a surface

Info

Publication number: WO1998045100A1
Application number: PCT/NO1998/000103
Authority: WO
Inventors: John Cheetham; Raymond Cheetham
Original assignee: John Cheetham; Raymond Cheetham
Priority date: 1997-04-04
Filing date: 1998-04-01
Publication date: 1998-10-15
Also published as: NO971572L; NO309417B1; NO971572D0

Abstract

An apparatus (1) and a method for embossing a relief shaped 3-dimensional pattern (2) on a formable surface (3) which is sucked towards and/or pressed against a non-resilient, hard surface (4) provided with a relief pattern (5) in the shape of protuberances and/or indentations, so that a corresponding but complementary pattern (2) is produced in the formable surface. The relief pattern (5) in the hard surface (4) consists wholly or partly of protuberances (5) which are constructed so that they can be fastened to and/or removed from the surface (4) according to requirements, and thus may be removed from or moved to other places on the surface (4); so that the pattern can easily be changed.

Description

AN APPARATUS AND A METHOD FOR IMPRESSING A RELIEF PATTERN IN AN SURFACE . ^{~~ ■ ■}

The present invention relates to an apparatus and to a method for embossing a 3 -dimensional pattern on a formable surface . The invention is intended mainly but not exclusively to be applied for producing plastic foils or sheets with a patterned surface. Foils or sheets with a formed surface of this kind either in plastic or other materials have found wide use in many different areas, for example in packaging, in market gardening, and in the building and construction industry as watertight membranes.

The invention can however also be used for other types of material, for example thicker sheet materials where the pattern in relief is found only on one side of the material whilst the other side can be flat.

In the forming of surfaces as described above it is today usual to use presses or rollers. The surface to be shaped or formed can be drawn to and/or pressed against a tool having a relatively hard surface with indentations or protuberances complementary to the pattern wished to be formed in the formable surface. Hereafter forming by tooling with indentations will be described as "negative" forming whilst forming by tooling with protuberances will be described as "positive" forming. Previously known equipment for producing such patterned surfaces has been of several types but common to all has been a one-piece, forming tool of a single and unchangeable construction. This means high tool costs and that the tooling must be changed when surfaces with different patterns are required. Tooling costs are very high for manufacturers wishing to produce foil materials with different surface patterns since new tooling is required for each new product . The time required to change the tooling also is considerable when a unchanged tool is used, causing an expen- sive stop in production whilst the manufacturer must have separate tooling available for each pattern it is intended to produce .

The cost of a single forming tool or roller for the production of a drainage sheet or foil for the building industry in a width of 2 metres can be as much as £ 80.000 at today's prices.

The present invention aims to provide a new method and a new equipment for producing such 3 -dimensional relief patterns on formable surfaces in such a way as to give much greater flexibility in production. Pattern changes are easier and cheaper since the pattern may be modified without changing or replacing the whole forming tool or roller.

A further objective with the invention is to provide tooling which can be modified easily for the production of different patterns, e.g. desired in connection with small production volumes.

This is achieved by using a method or providing an equipment in accordance with the patent claims stated below. In order to give a clearer understanding of the present invention reference is made to the detailed description below together with the accompanying drawings where: Fig. 1 is a section through a roller type forming apparatus showing the principle of forming a pattern in a continuous length of material, fig. 2 shows part of the surface of an apparatus for forming a relief shaped pattern according to the present invention, fig. 3 shows a protuberance forming part of the apparatus shown in fig. 2, fig. 4 shows another type of protuberance similar to that shown in fig. 3, fig. 5 shows a cross section through a protuberance according to fig. 3 or 4, fig. 6 shows a detail of an apparatus according to fig.

2, fig. 7 shows a detail of an apparatus for forming having another construction but nevertheless within the scope of the present invention, and fig. 8 shows an alternative embossing apparatus.

When appropriate the reference numbers used in the individual figures are the same. The figures are drawings showing the principles involved and in sufficient detail to make clear how the invention functions. It should also be noted that neither the different figures nor the details in one and the same figure are necessarily to the same scale.

In fig. 1 a cross section is shown through an apparatus 1 according to the present invention for forming a relief shaped 3 -dimensional pattern 2 on a formable surface 3 which is drawn to and/or pressed against a hard surface 4 provided with a relief pattern 5 in the shape of protuberances and/or indentations.

The forming or embossing apparatus 1 shown in fig. 1 has a cylinder with protuberances 5 which rotates during the process of production. Which way the cylinder rotates is in principle unimportant as the arrows indicate but, as the foil is shown here the cylinder rotates anti-clockwise. During rotation a continuous length of formable material 3 is drawn over the surface 4 of the cylinder or roller. In that the material 3 is pressed against the surface 4 of the cylinder the protuberance 5 will form the material 3 so that corresponding studs 2 are formed in this and remain permanently formed after the material 3 has left the cylinder. It should be noted that the pressure between the cylinder 4 and the continuos material 3 can be obtained in different ways. For example, the tension in the material 3 can be adjusted so that the material is pressed in against the roller or cylinder. Alternatively a vacuum can be applied within the cylinder 4 which, providing there are small holes in this, will draw or suck the material 3 into the surface of the cylinder so that forming takes place. A further way in which forming can be achieved is by using at least one extra roller indicated in the diagram in a broken line as 4 ' . This roller can have a surface which is complementary to the surface 4 on the first cylinder or it can, quite simply, be deformable in an elastic fashion so that the continuous material 3 is pressed in against the surface 4. The foil is preferably a plastic foil with a thickness from 0,2 mm up to approx. 5 mm or more. The surface of the cylinder or roller 4 can be of a chosen length and its axis is vertical to the surface of the paper. The number of protuberances 5 on the surface 4 and their positioning is determined by the desired appearance of the finished product. The protuberances or studs 5 can be alike or different but when the production tool is cylindrical as in this case, the pattern must repeat for each revolution.

Previously, prefabricated rollers had to be used with integral or fixed protuberances or studs whilst some rol- lers have had press fit studs or protuberances . In neither case has it been possible to move or remove these without damaging the studs or the roller or both. The roller is normally of steel and the production costs of such rollers with a fixed pattern can be £80,000 or more depending on size. It is therefore very expensive for a manufacturer to produce foils with different designs since separate and individual forming rollers are required for each design. Additionally it is time consuming to change such rollers in the production equipment where the whole process is normal- ly based on forming the desired pattern immediately after a foil has been extruded and whilst it is easy to form.

It is in this connection that the present invention has its application in that the protuberances or studs 5 are not an integral part of the surface 4 but are produced as loose and separate studs 5 which can be moved about the roller to the desired position or removed entirely from its surface. A combination can of course be used where the roller is equipped partly with integral or permanent protuberances or studs and/or indentations whilst other pro- tuberances or studs are produced in accordance with the invention so that they are movable and/or removable and can be fastened to indentations in the surface 4, to the surface 4 where this is smooth or to the surface 4 where this already contains smaller protuberances or studs. Both the height, the shape and the extent of the individual studs can be varied as required.

The invention is therefore also related to the application and design of individual protuberances or studs 5 which can be positioned or removed easily and to means and equipment for making an exact location of the studs possible with a minimum of preparation by the producer.

With a forming or embossing apparatus according to this invention it is possible for a manufacturer to completely redefine the forming roller in a short time and with untrained personnel and yet achieve a high degree of precision.

The method of fastening the protuberances or studs to a surface, for example the surface of a cylinder, can be varied since different techniques can be used either singly or in combination. The present invention intends primarily to use magnetism in order to hold the loose protuberances or studs in place, probably in combination with a previously machined pattern, for example a basic pattern of channels or indentations on the roller surface enabling an exact positioning of the individual protuberances or studs to be made. Other fastening methods such as glueing, screwing or suction using vacuum can be used either individually or in combination. The following example describes how magnetism, surface indentations and to a lesser degree vacuum are used to fasten such studs. This does not mean, however that the methods described cannot be used individually, either alone or in other combinations.

Fig. 2 shows a section of a cylinder surface 4 with a basic pattern in the shape of machined channels 9 as inden- tations travelling along and across the surface of the cylinder 4. At specific places at the bottom of such indentations, for example at the intersection of two such indentations 9, small holes 8 can be made to transfer a vacuum produced inside the cylinder, in other words on the under- side of surface 4 as shown in fig.2. It should be pointed out that such holes 8 can be placed between and/or directly under the protuberances or studs 5. The protuberances 5 , shown in fig.2 are separate metallic studs which can take several forms . Figs . 3,4,5, and 7 explain in more detail how such studs 5 can be constructed.

The stud 5 may, in one embodiment, comprise an external metallic cap 14 with an axial hole of limited depth 15. The dimensions of hole 15 are such that a relatively thin- walled cylinder 7 of non-magnetic material can be press or force fitted into the hole. The internal diameter of this non-magnetic cylinder is such that it can receive and hold a permanent magnet of suitable diameter and length 6. The permanent magnet 6, the non-magnetic lining 7 and the housing 14 shall be assembled to one moveable unit and the con- nection between the separate components can be made by any method as long as these fit together securely. A simple method which has proved itself in practice is to assemble the components by press fitting them. The non-magnetic lining 7 gives the magnet greater effect in holding the stud in place.

As can be seen from the figures, the housing has small legs 10 which are so shaped as to fit into the indentations or channels 9 which make up the basic pattern in the surface 4 of the roller. This construction makes it simple to position the studs correctly where they are required on the surface of the roller and so that they cannot slide out of the chosen position in relation to the prefabricated basic pattern of channels 9 in the surface 4. It should also already here be mentioned that if a vacuum is applied from the inside of the roller or cylinder it will contribute to holding the studs 5 in position in that they will be drawn to the surface 4 by suction through hole 8, if any of these are covered by the studs and, more importantly, the foil 3, which is stretched round the roller, will be drawn towards the surface of the roller 4 and well into the corners which occur between the studs and surface of the roller 4. This is particularly the case since the vacuum is effective in the zone between the stud 5 and the roller surface 4 and draws the foil tightly into these changeover zones. It should also be mentioned that the protuberances or studs 5 can be fastened in other ways for example with one or more screws 11 as indicated in fig. 4 or with the help of adhesive applied to the underside of the studs. If adhesive is used it may preferably be of a type which hardens on cooling and softens on reheating. There are many such adhesives on the market and it is possible to use these together with other fastening methods or alone. If screws are employed screw holes not in use can be plugged or sealed with short screws . Fig. 6 shows a detail of the roller surface 4 particularly suitable for the production of a foldable bathroom membrane in accordance with the Norwegian registered design No. 70.541 when the roller is used without the applied protuberances or studs 5 and for the production of a foldable bathroom membrane with studs in accordance with the

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Claims

C l a i m s

1. An apparatus (1) for embossing a relief shaped 3- dimensional pattern (2) on a formable continuous surface (3), which is led over a firm, hard cylinder/roller surface (4) equipped with a relief pattern (5) in the shape of protuberances and/or indentations and in close contact with this so that a complementary pattern (2) is produced in the formable surface (3) c h a r a c t e r i z e d by the relief pattern (5) on the roller surface (4) partly or wholly consists of protuberances (5) which are arranged to be fastened and/or loosened from the surface (4) as desired, so that these protuberances can be removed or fastened in other positions on the surface (4) ; so that the pattern (2) can easily be changed in that the protuberances are equipped with a permanently magnetic material whilst the surface (4) is of magnetic material so that fastening of the protuberances (5) takes place with the help of permanent magnetism.

2. Apparatus (1) according to claim 1, c h a r a c t e r i z e d by that there is at least one permanent magnet (6) fixed with in each protuberance (5) .

3. An apparatus according to claims 1-2, c h a r a c t e r i z e d by that the permanent magnet (s) (6) is (are) fastened by press fitting preferably in a sleeve (7) of non-magnetic material such as brass which, in its turn is press fitted into the protuberance (5) and/or into the hard surface (4) .

4. An apparatus according to claims 1-3 and where the hard surface (4) comprises holes (8) at least where the protrusions (5) are attached, c h a r a c t e r i z e d by there being a vacuum source connected to the underside of the hard surface (4) so that a vacuum can help to hold the protuberance (5) in the desired position.

5. An apparatus according to claims 1-4, c h a r a c t e r i z e d by that the hard surface (4) and the protuberances (5) are supplied with complementary surface irregularities (9,10) which together contribute to hold the protuberances (5) in their desired positions.

6. An apparatus according to claims 1-5, c h a r a c t e r i z e d by that the protuberances (5) at least at some places, have a certain play to the hard surface (4) and that the apparatus (1) is so equipped that a vacuum active on the underside of surface (4) will contribute to holding the protuberances (5) firmly against the surface (4) , and that the formable material (3) is drawn well into the corners between the protuberances (5) and the hard surface (4) during the embossing process.

7. An apparatus according to claims 1-6, c h a r a c t e r i z e d by that the hard surface (4) is cylindrical and that the formable material (3) is a foil fed continuously over part of the cylinder's angular circumference (╬▒) whilst the cylinder rotates, in such a way that a continuous length of material with a formed surface (13) is produced.

8. An apparatus according to claims 6 or 7, c h a r a c t e r i z e d by that the length of the pattern's repeat (12) is equivalent to or a whole fraction of the cylinder's circumference.

9. A method for embossing a relief shaped 3 -dimensional pattern in a formable surface (3) by passing a hard surface

(4) with a complementary shaped pattern (5) in against a formable surface (3) so that it is deformed by the pattern, c h a r a c t e r i z e d by that separate prefabricated pattern forming protuberances (5) constructed to be fastened to and/or removed from and/or moved within the hard surface (4) , are removed from and/or placed on and/or moved within the hard surface (4) before the formable surface (3) and the hard surface (4) are forced together for in this way to modify the 3 -dimensional pattern to be produced; since the protuberances are held in contact with the surface (4) by magnetism alone while the correct positioning is ensured by co-operation with the irregularities in the surface whilst the removal of the protuberances can take place by manual operations.