WO2009101254A1

WO2009101254A1 - Method for shaping a film-like/sheet-like material

Info

Publication number: WO2009101254A1
Application number: PCT/FI2009/050106
Authority: WO
Inventors: Timo Valkas
Original assignee: Innoplan Oy
Priority date: 2008-02-13
Filing date: 2009-02-11
Publication date: 2009-08-20
Also published as: EP2247430A4; EP2247430B1; FI20080105A0; EP2247430A1

Abstract

Method for shaping a film/sheet, particularly for making three-dimensional shapes in it, in which case the contours of the shape to be formed are warmed/heated and the film/sheet is stretched along the heated contour, in order to cause the part of the film/sheet inside it to deviate from the plane of the surface. The heated contours are created by, for example, directing a focussed, moving beam of thermal radiation onto it.

Description

Method for shaping a film-like/sheet-like material

The present invention relates to a method for shaping a film-like/sheet-like material. In particular, it relates to a method for changing the shape of a membrane or sheet, especially to create various three-dimensional shapes in a film or sheet.

Many different methods are used to shape plastic sheets. One example is the creation of Braille printing intended for the blind to read. Because plastic is a very common material in many applications, various articles made with the aid of heating and then shaping are made for very many different purposes.

In order to shape plastic, for example, into the shape of a cup, a mould can be used, into which plastic material, softened with the aid of heat, is pulled with the aid of a vacuum. A typical example of this kind of procedure is disclosed in the German application publication 10349156. As a source of heat, a laser source, for example, can be used, by means of which specific areas of a generally flat sheet- like material are heated, after which shaping takes place by suction against a mould.

A method is known from US patent application 2002/0062161 , in which a wall deformation is created in a piece with a closed volume, or in a sheet, by heating the wall with a laser light and causing a pressure difference in the wall/film, which causes the wall to bulge outwards, in such a way that the most heated parts bulge more than the less heated parts. Thus, the shape is created by the differential stretching of parts heated to different degrees.

The present invention is intended to create a method, the use of which is in no way restricted, for example, to the use of a mould, or to mutual differences in areas heated to different degrees. According to the invention, the intention is to create three-dimensional patterns in a very versatile and simple manner. In brief, the elastic state of especially thermoplastic materials is exploited according to the invention, in such a way that the contours of a free-form image to be formed on a film/sheet are heated, for example, by rapidly moving or scanning a focussed bundle of thermal radiation, to a sufficiently homeothermal desired temperature and pressurizing the other side of the film. The pressure seeks to press the film, which stretches from the heated contours of the image, so that the image is transferred from the surface of the film to a raised position. The unheated area remaining within the contours does not alter its shape in any way in response to the pressure, but retains its original shape.

The aforementioned and other advantages and benefits of the present invention are achieved in the manner described as characteristic in the accompanying claims.

One embodiment of the invention is described with reference to the accompanying patent drawings.

Thus:

Figure 1 shows the initial situation, stage 1 ;

Figure 2, for its part, shows the event of stage 2;

Figure 3 shows the intermediate product of stage 3; and

Figure 4 shows the final product.

Thus, Figure 1 shows an essentially sheet-like initial product 1 , on which a shape to be made is outlined by dotted lines 2. The shape 2 is bordered by its edge line, following a line marked by broken lines 3, along which the area is heated to a temperature that permits a pressure-pulse stage, which takes place next. The line in question is line 3, which depicts the contours of the next stage. The source of the heating radiation 4 is marked with the reference number 5. The source can be, for example, a laser-light source. No more detailed reference is made here to laser technology, which is one possible heat source, because this area of technology will be conventional technology to one skilled in the art.

In any event, the intention is to heat the contours of the image in the material to such a temperature that, in the following stage, they will be sufficiently elastic for the shaping to be performed by vacuum and/or excess pressure, so that the heated parts of the material sheet or film heated along the desired contours will stretch, and thus the unheated area remaining inside the heated lines will rise from the level of the material, in the direction of the lower pressure.

Figure 2 is intended to show the vacuum and/or excess pressure treatment described above. In this case, a lower pressure prevails above the sheet 1 than below it, so that image heated along the contours rises upwards from the level of the rest of the sheet/film. The rise thus takes place essentially from a linear area.

Figures 3 and 4 will be self-explanatory. By performing consecutive heating/stretching operations sufficiently many times, the shape 2 can be created. As can be easily concluded, the shape, as such, is of no significance in terms of the final result, any shape whatever can be manufactured according to the invention by performing heating along the contours of the desired shape and performing vacuum and/or excess-pressure treatment.

In the above figures, the shape is shown as a very rough result, for reasons of clarity. In practice, the final shape is achieved by slicing the final 3D shape into very thin 2D slices, from which the shaping of one slice at a time in the desired direction is performed as consecutive operations. Even a relatively simple final shape contains a numerous group of stages.

Negative shapes can also be made in a shape according to the invention. This refers to the fact that the desired shape is created with the aid of heating and excess or vacuum pressurization, which excess or vacuum pressurization is performed in the opposite direction to the general direction of the overall shape. In this case, it is also possible, if necessary, to exploit the memory property of the material, when the re-heating of the contours will return it to its former shape.

It is obvious, that, according to the invention, very many different types of material can be used. The material that most readily comes to mind is a plastic material. However, other materials that become plastic at a certain temperature are also suitable for use according to the invention. For example, nearly all metals soften to become malleable at a certain temperature specific to them. One interesting area is also composite-structure films/sheets. Thus, whether the use of a specific material will succeed or not depends only on variables such as the dimensioning of the heating power source, the duration of its operation, and similar.

It is also obvious that reference to a sheet or film includes a large variation in material thicknesses.

The temperature is controlled in some suitable manner. A large range of various types of alternative ways for this purpose can be found from different fields of technology, so there is no need to go into them in greater detail here. However, it can be mentioned that temperature can be measured and control performed with its aid, for example, with the aid of a heat camera based on infrared technology monitoring the laser beam. Temperature monitoring is, for its part, used in the general control of the process.

In this connection, it should be noted that, according to the aforementioned procedures, the heating can take place in such a way that a continuously heating radiation beam is moved along the contours of the image to be formed, when the material will heat at the contours.

Another way is one, in which the thermal radiation moves along a specific, usually backwards and forwards path, and heating occurs locally only at points located on the contours of the image being formed. The movement of the thermal radiation can be achieved by moving a component creating thermal radiation, but more probably it will take place in such a way that the control of the thermal radiation takes place with the aid of mirrors, lenses, or corresponding optical elements. As a third alternative, a solution can be presented, in which the heated area is created in such a way that a pattern shaped to correspond to the area to be heated by a thermal radiation beam is created in the heating head, which is, as such, aimed at the material to be heated, when a heated area, corresponding to the contours of the shape, arises in a single operation. There are several ways of forming a thermal radiation beam of a desired shaped, of which certain optical methods are the most likely.

A manner of this kind can be envisaged as being very advantage when a relatively simple product is being made in a large series.

A common feature in all of the ways referred to is that the warming/heating is performed only along the contour of the area to be raised.

According to the method according to the invention, the heating/pressurization cycles can be repeated for the desired number of new co-ordinates, which means that three-dimensional surfaces can be formed from a film/sheet in the same manner as in vacuum moulding, but in the present method the geometry of the piece is created directly by numerical control, without moulds.

It should also be noted, that shapes can also be formed, for example, in such a way that, in one stage, a three-dimensional shape is made in one way or another, as already stated, as a 'negative' shape relative to the previous stage. This refers, for example, to a situation, in which the product is shaped originally, by means of vacuum forming, for example, with the aid of a mould. For vacuum forming to be possible, the product must not have protrusions extending in opposite directions, which would prevent it from being detached from the mould.

By means of the method according to the invention, the shaping of a vacuum- moulded piece can be advantageously continued by making protrusions from it in any direction whatever. As such, the method is suitable for very many different purposes. If desired, in addition or solely temperature and/or distance measurement can be used as variables controlling algorithms. Return and reshaping according to the prior art can also be used in this method.

Experiments have shown that liquid too, as well as atmospheric pressure (gas) can be used for shaping, in which case the control of the shaping becomes specified as a mathematically calculable change in volume of each free-form change in shape.

In practice, an application can be based on a computer-based system, in which the desired three-dimensional model is loaded into the system, which slices the model into parts and which controls the heating and operating unit according to the model produced, the unit performing the shaping in stages of the film or sheet by heating specific contours, performing the stretching of the material at the contours with the aid of pressure, and thus manufacturing the final product.

Any known system whatever, with the aid of which a targeted heating effect can be created, can be used for heating. Such systems are particularly based on the use of laser or infrared-range light and on possible optical concentration or reflection of the light.

Because the return/returning of the film is not necessary in all cases, this extends the range of materials available for use.

The invention can be varied in many ways without nevertheless deviating from the scope of protection of the basic idea of the invention and the accompanying Claims.

Claims

1. Method for shaping a material film/sheet, particularly for making three- dimensional shapes in it, in such a way that the film/sheet is warmed/heated and a pulse of excess pressure/vacuum is induced in a medium on the other side of the film/sheet, characterized in that the warming/heating is performed along a contour of the three-dimensional shape to be formed, to a temperature which will permit a change in the shape of the film/sheet in the area of the heated contour and will create stretching along the heated contour, in order to cause the unheated part of the film/sheet inside the contour to deviate from the plane of the surface.

2. Method according to claim 1 , characterized in that the heated contours are formed in the film/sheet by directing a focussed, moving beam of thermal-radiation onto it.

3. Method according to claim 1 , characterized in that the final 3D shape that is the subject is divided into a group of 2D slices, the contours of each one of which act as the areas to be warmed/heated.

4. Method according to claim 1 , characterized in that the three-dimensional shape is created in the film/sheet by repeating several times the heating and stretching stage directed to different locations.

5. Method according to any of the above claims, characterized in that the film/sheet is of plastic, particularly of thermoplastic.

6. Method according to any of the above claims, characterized in that the film/sheet has a composite structure.

7. Method according to any of the above claims, characterized in that the film/sheet is of metal or a metal alloy.

8. Method according to claim 1 , characterized in that pulses of the pressurized medium are used to shape the film/sheet in different directions in different stages, if necessary.

9. Method according to claim 1 , characterized in that the warming/heating is performed by using a focussed source of infrared or laser light.

10. Method according to any of the above claims, characterized in that, in the shaping, a computer-based system is used, into which the three-dimensional model to be formed is loaded.