Technical field:

The present invention relates to a method for affixing elements using a polymer and a device for carrying out the method.

Gluing, using a polymer, is employed to a certain extent for industrial affixing of elements to a surface. This method is particularly important for fixation to surfaces to which it is difficult to attach something using methods which require the formation of, for example, holes or slots in the material, or which require welding or soldering. An example of such is the affixing of attachments to panes of glass which are difficult and expensive to work with and which furthermore simply cannot be joined with elements of different material via welding or soldering. An important area is thus the joining of vehicle windows to other elements where gluing using a polymer is widely applied. Accordingly, the invention is applicable to fixation in connection with panes of glass, such as vehicle glass.

Background art: With the evolution of polymers, the possibilities to achieve reliable glued joints between glass and another material have risen. In contrast to adhesives of conven¬ tional nature, polymers can generally also be used in thick layers, whereby large play can be padded out and, more importantly, an elastic fixation can be achieved if a polymer with suitable properties is chosen. Here poly- urethanes have proved to be particularly advantageous.

Polymer adhesive can be made to cure by means of a catalyst which is supplied to the adhesive when the adhesive is prepared for use, or which exists in the surroundings in which the adhesive is used. In the latter case, the catalyst can be the humidity or metal ions in the air which come into contact with the adhesive at its contact region. However, such polymerization takes a certain time during which the glued objects must be protected against low temperatures and force effects. Polymerization can also occur by exposing the adhesive and the objects to be glued to a relatively high tempera¬ ture, in the order of 100°C. This can lead to a shorter polymerization time, but the heating itself can take a considerable time, particularly if the parts to be adhered are large. Heating to this temperature can also involve risks of deformation of the parts or crack- formation, the latter being a particularly large risk with glass.

Thermal setting is used in the present solution to avoid said disadvantages when using a catalyst. Microwaves are used for the heating. This gives a quick heating which can, more or less, be restricted to the adhesive itself, whilst the said parts do not need to be heated. This is particularly important for methods involving gluing of glass since glass can be sensitive to temperature changes and, in any case, requires a uniform heating. Since in the present case gluing with an adhesive which forms an elastomer is desired, polyurethane is proposed and is used in a layer which is one or a few millimetres thick. Thus, it is important that the layer of adhesive fully cures, and this can be attained using microwaves which, if the adhesive has suitable characteristics, causes simultaneous heating of the whole mass. A thick, elastic layer between an attachment and the pane of glass

provides a favourable fixing of the latter and, at the same time, with winding windows for example, changes in position between the pane of glass when it moves in its guides and the lifting mechanism can be compensated for by the resiliency of the attachment with the window pane.

Object of the invention:

Previously, such gluing has been performed through heating a polymer with the aid of microwaves, which thereby effect curing. The customary method thus employed for heating with microwaves consists of placing the parts which are held together with the tacky polymer in a chamber in which microwaves are generated, i.e. a micro¬ wave oven. However, this has not proved to give a satisfactory result with such attachments which to some extent include the polymer, and particularly if the attachment is made from metal which screens the microwaves. The method can also not be used with large objects since an even distribution of the waves cannot be achieved in large chambers.

Solution:

The method for affixing elements to eachother using a polymer during heating thereof by means of microwaves to achieve polymerization is performed such that the elements are brought into communication with the orifice of a microwave guide which is arranged for generation of a stream of directed microwaves, which wave guide is arranged in such a position and at such an angle with respect to an opening in a first one of the elements which is arranged to partially surround a second one of the elements, with the latter element projecting through the opening in the first element, that the microwaves are directed towards the polymer positioned in a space within the opening between the two elements and which polymer is to be heated. The device according to the invention is

provided with a microwave guide in the above-mentioned position and at such an angle with respect to the elements that the microwaves are directed in said manner.

Advantages:

By means of the invention, a method is proved which permits affixing of elements by heating of a polymer with the aid of microwaves even in the case where the element is of the type which screens microwaves. The invention further relates to the provision of a device for carrying out such a method.

Description of the drawings: Two embodiments of the invention will be described in the following, whereby one has two versions, as shown in the attached drawings.

Fig. 1 shows a section through an attachment forming part of the first embodiment according to the invention and seen along line II-II of Fig. 3;

Fig. 2 shows the attachment in the same direction as Fig. 1 together with a pane of glass which is used in the performing of the method;

Fig. 3 shows a part of the device, the attachment and the pane of glass seen from above;

Fig. 4 shows on a smaller scale than the above figures the device in its entirety in a partially sectioned side view of a first version in a direction of view corresponding to Figures 1 and 2;

Fig. 5 shows in the same manner as Fig. 4 the device in its other version, and

Fig. 6 shows in a corresponding way to Fig. 2 the other embodiment.

Description of preferred embodiments:

A pane of glass seen in section in Fig. 2 is denoted by reference numeral 1. Reference numeral 2 denotes an attachment which is to be affixed to an edge of the pane. The attachment, which is shown in Figures 1 and 2 from the side and in section, whilst shown in a front view in Fig. 3, is made from aluminium and presents an attachment part 3 and a connection part 4. The connection part 4 is intended to be fixed to a fastening member for locating the pane of glass in a window frame. The attachment shown in the figures is particularly intended to hold a pane of glass to a window-winding mechanism of a vehicle. The pane of glass is thus arranged to run in guides and can be moved between various open positions by means of a window-winding mechanism which acts on the pane of glass via the attachment 2. The part 4 which is connected to the window-winding mechanism is of no interest to the present invention and thus shall not be further described. The attachment part 3 is U-shaped with two shanks 5 and 6 and a channel 7 therebetween. The channel is provided with a plurality of ribs 8 on its sidewalls. The channel's opening is funnel-shaped.

From Figures 1 and 2 it can be seen that the sides of the channel, i.e. shanks 5 and 6, are provided with guide projections 9 and 10. These guide projections are formed by pushing in regions of the shanks so that recesses are formed on the outer side as shown in Fig. 3. The distance between the insides of the guide projections is somewhat less than the thickness of the pane of glass 1.

From Fig. 3 it can be seen that the attachment is formed from a length of an extruded section which is sawn off so that ends 12 and 13 are formed.

In Fig. 2 it can be seen how a plastic material 14 is placed in the channel 7 in the region which is formed between the walls of the channel and the pane of glass, which is centred in the channel by means of the projections 9 and 10. The plastic material consists of a paste-like starting material for a polymer. This is cured during the affixing operation through heating. A suitable material in this connection is polyurethane. With certain additives, the polyurethane can be made to thermally set. These additives are of such a type that they are agitated by microwaves and give a heating effect to the polymer when subjected to microwave irradiation.

In order to receive radiation, an opening to a wave guide 16 is positioned opposite the opening to the channel 7. The wave guide is formed in this case by a passage in a body 17 with said opening directed towards the open end of the attachment. The wave guide is inclined to the pane of glass at an acute angle α. Angle α should be less than 45° though it is heavily dependent on the shape of the attachment and the wave guide's position in relation to the opening of the attachment. A support 18 is provided on the body 17 for the pane of glass l.

The microwave system is shown in Fig. 4 in its entirety. The same figure reference numerals as those used in the earlier figures will be used here even though the embodi¬ ment may differ slightly. Accordingly, the pane of glass 1 shown in Fig. 4 is curved, which nowadays is common for vehicle glass. The attachment 2 has the same shape as shown earlier. The support 18 is also present again, and

is complimented with further supports 19 and 20. Likewise, the body 17 and the wave guide 16 are also present, the wave guide being formed by the passage through the body 17 forming an extension of a conduit 21 which is connected to a microwave generator 22 arranged to generate microwaves in the wave guide.

As shown in Fig. 4, the side 24 of the body 17 facing the glass is adapted to the shape of glass so that a gap of say 30 millimetres is formed between the body and the surface of the glass. The body 17 is placed in a housing 25. Both the housing and the body are made from conduct¬ ing material, for example the housing from sheet metal and the body from cast aluminium.

The housing 25 can be closed with a lid 26, also of a conducting material. The lid 26 has an inner surface 27 which, like the surface 24, follows the surface of the glass with a gap therebetween. A propeller-like wave reflector 28 is accommodated in the surface 27 of the lid 26 above the attachment 2 when the lid is closed, which wave reflector can be rotated by an electric motor 29 recessed in the lid.

Besides the wave guide's passage, a passage 30 is formed in the body 17 which opens towards the attachment 2 and which is connected to a fan 31 for supplying warm air which can be blown towards the attachment. From the space between the surfaces 24 and 27 which is intended to contain the glass 1, there is an outlet in the form of a tube 34 connected to an electron filter. Tube 34 is arranged to be able to evacuate hot air and gases from the space. The filter 33 hereby prevents the distribution of microwaves outside of the microwave system.

The version of the device shown in Fig. 5 is more or less provided with the same equipment as the device according to Fig. 4. The previously described equipment, like the elements which are to be treated in the device, will thus not be described, except for the differences.

It can be seen from Fig. 5 that the device is not made as a lower housing and an upper lid, but instead as a lower bed 50 and an upper hood 51. The bed consists of a lower board 52 and an upper board 53 with both preferably being of metal or a compound material which is capable of shielding microwaves. The lower board 52 is provided with a passage 54 through which the wave guide extends (compare 21 in Fig. 4) and a second passage 55 through which the heating fan operates (compare 31 in Fig. 4) .

The intention is that the thicker, lower board 54 shall be a part of a microwave arrangement which is intended to be used for treatment of elements of various sizes and design, though with the common factor that an attachment or another element partially surrounds another element as described earlier. Both passages 54 and 55 are thus adapted to be able to facilitate the treatment of such elements within a large range of sizes. The board 52 is accordingly not intended to be exchanged when changing from one type or size of element tc? another.

The board 53 is thus individually manufactured for each type of element. It is provided with the previously described supports, which are adapted to the product which is to be manufactured. Furthermore, other adaptations can be necessary, as is evident from the following.

The hood 51 consists partially of a lid-like section 56 of sheet metal and partially of an insert 57. The lid-

like section 56 is primarily intended to be made in a certain size within the range of sizes for which the device is to be used. This is, however, not essential and the section can be made with various sizes though it is of course desirable from a manufacturing and storage view point that standardization is employed. What is adapted to the specific product is, however, the insert 57. As described previously, a lower surface 58 of the insert follows the product with a restricted gap and additionally supports the previously mentioned wave reflector with its motor.

The insert 57 is made so as to be inserted in and supported by the part 56. What is important for the function is that the said lower surface 58 and the insert can be made in the most appropriate manner. Here it is shown in the form of a solid body, though it is also possible that it be made as a hollow body. The material for the body is of course affected by microwaves. A suitable design is to make the main part of the body from an easily workable plastic. This can then be provided with a metal layer on the surface 58 acting as a reflector and a screen for the microwaves.

As previously stated, it is desirable that the space in which polymerization occurs is as small as possible so that the poisonous vapours, which can be produced, can be most effectively handled. As previously described in connection with Fig. 4, this can be achieved by positioning the product with a relatively small gap between the surrounding surfaces. With the version according to Fig. 5, this gap is greater on the lower side of an non-planer object since this slopes with respect to a plane surface, i.e. the board 53, since it is desirable to limit production of curved surfaces during manufacture. It can thus be appropriate to further

enclose the product and this is done using partition strips, a strip 59 in the board 53 and a strip 60 fixed to the insert 57. Each of the strips supports an elastic packing 61,62 respectively. The lower edge of the hood 51 is similarly provided with a circumferentially extending packing 63 for contact with the board 53. The packing 61 and 62 extends across the entire width of the product and up to the sidewalls of the hood so that the space in which polymerization occurs (to the left of the described seal) is completely separated from the remainder of the space in the hood.

An outlet is provided from the space in which polymeriza¬ tion occurs for the withdrawal of the produced gases (compare 34 in Fig. 4) . This outlet is not shown but can for example be positioned to the side of the passage 55.

The said elastic packing 61,62 and 63 is preferably made from silicon rubber containing carbon. With the correct proportion of this compound, the material will shield microwaves whilst at the same time having elasticity so that good sealing properties are attained. Other materials comprising an elastomer with the addition of a conductor can also be used. Another possibility could be an elastic packing with a thin, enclosing shielding sock of metal weave. An embodiment which provides very good sealing is one with two elastic packings, whose material is chosen purely on the basis of its sealing properties and not its wave-shielding properties. Between these two seals a cavity is formed which, after closure of the device, is subjected to a vacuum. In this way, the parts are pushed towards each other due to the outer air pressure and any gas which may leak pass the inner seal will be evacuated via the suction arrangement necessary for the vacuum. This gas seal is complemented by one or more strips of the said type with shielding effect

against microwave irradiation. Thus, for these strips, no regard has to be taken to the sealing against gas leakage.

An advantageous development of the device according to Fig. 5 which, however, is not shown here for reasons of space, is to allow the whole device to be inclined so that the surface of the board 53 slopes. In addition, it is assured that the board has no open holes. This is done by closing the wave guide 54 with a plate of material which is transparent to microwave irradiation. The passage 55 can be provided with a grill or may be located outside of the area where the elements 1 and 2, and particularly the element 1, are positioned. Alternative- ly, the passage 55 can be provided in the upper surface 58 and thus need not be covered.

This arrangement is suitable for when the device is being used for what it is principally intended for, namely the affixing of attachments to panes of glass. Since the glass is susceptible to crack formation during heating, it is possible that, if non-uniform stress conditions occur, the glass breaks. If this should occur with vehicle glass made from toughened glass, then a large quantity of fragments will result. Thus, if the board slopes and is substantially flat and without openings, the broken glass will slide from the board when the hood is raised and the device is then ready for further operation with new elements without requiring any cleaning. Naturally, the supports for the pane of glass must be so formed that the glass can be held during the curing operation inspite of the slope as already described.

An attachment 36 intended for joining two panes of glass 37 and 38 is shown in Fig. 6 as the second embodiment of

the microwave system. The intention is that the attachment 36 consists of four strips with the cross- section shown in Fig. 5, which are itered together to form a frame which surrounds the panes of glass 37,38. Since the attachment is adapted to maintain the panes at a certain distance from each other, so called insula¬ tion glass is created, i.e. a pane with better insulation properties than a single glass pane since both of the panes are separated by an air or gas-filled gap.

For this purpose, the attachment is provided with two channels 39 and 40, one channel for each pane. As for the attachment 2, the channels are ribbed. In the fastened condition, the edges of the panes are surrounded by polymer adhesive, as denoted by 41 and 42 respectively. The attachment is so placed with respect to the panes that they are centrered in their respective channels. This can be achieved using spacing elements, such as the guide projections 9 and 10 in the first embodiment, or by locating the attachment and the panes during joining, using supports in certain positions with respect to each other.

In this instance, the panes are surrounded during polymerization by conducting bodies 44 and 45. Each body comprises a passage which forms a wave guide, denoted by 46 and 47. The surfaces 48 and 49 of the bodies follow the outer surfaces of the panes with a gap therebetween, as described previously. The wave guides again form an acute angle to the surfaces of the panes and are accordingly directed towards the open ends of both channels 39 and 40 of the attachment 36.

The device according to the second embodiment is made in mostly the same way as that shown in Figures 4 and 5.

However, double wave guide passages must be provided for

supplying microwaves from the generator and, in the second embodiment, it is preferable for each wave guide to have its own generator. It is foreseen that apparatus for supplying hot air, for distributing microwaves and exhausting hot air and gases are arranged along the lines as described in connection with Fig. 4.

In the above, just one wave guide, or in the second embodiment two wave guides, have been described. This is because the devices have been shown in certain cross- section. In the transverse direction, the wave guide or wave guides can be divided into many. Accordingly, if several attachments are to be affixed according to the method of the first embodiment, the arrangement must of course be repeated for each attachment if they are not so close together that they can be covered by a single wave guide. If the attachment is long, then a division of the wave guide into several passages may be necessary so as to ensure correct guiding of the microwaves in order for them to agitate the adhesive along the whole attachment. As can be appreciated, in the second embodiment the attachment is used to form an insulation pane of considerable length since the attachment extends along all the sides of the pane. Thus, the attachment forms a square or a rectangle with the parts positioned at angles with respect to each other. Thus, the wave guide system must be adapted for such an attachment, generally with four wave guides for the four principal directions. These wave guides can, in turn, be divided along respective edges for suitable distribution of the microwaves.

When carrying out the method of fixation with the apparatus according to the first embodiment. Figures 1-3, the attachment is affixed to the edge of the glass, as shown in Fig. 2. This is achieved since the attachment simply projects over the pane and the distance between

the guide projections 9 and 10 is such that the attach¬ ment is tightly pinched round the pane due to its own resilience. The attachment is assumed to be made from aluminium or a hard plastic. The adhesive 14 can be applied either in a sufficient quantity before mounting the attachment so that the pane forces the adhesive to fill the gap around the side of the pane, or via injection after mounting the attachment to the pane.

When using the apparatus in Fig. 4, the pane is placed in the open housing 25 on the supports 18,19 and 20. The attachment 2 is placed such that the opening to the channel 7 is directed towards the wave guide 16 and with the attachment approximately centrally above the passage 30. The lid 26 can now be closed and the polymerization process can begin. Thus, the fan 31 is energized to direct warm air via the passage 30 to the attachment so that it receives a certain preheating. This is particularly necessary if the attachment is metallic, for example aluminium, since the molecules in a metal are not agitated by microwaves. If no separate heating of the attachment is carried out, then it can occur that the attachment draws heat from the adhesive, which is the component which is to be heated, and thereby the polymerization process could be disturbed. After a suitable preheating time, and when the attachment has reached a suitable temperature, the microwave generator 22 is activated and the wave reflector 28 must also be rotated simultaneously. Any fans connected to the outlet pipe 34 are also turned on.

The microwaves are directed along the wave guide 16 and, via its shallow angle, into the channel 7 of the attach¬ ment. The pane of glass does not prevent the spreading of the waves to any great extent and thus they can spread along the channel, since the channel is ribbed, a wide

reflection in the material of the attachment is achieved, which distributes the microwaves in the adhesive. At the same time, the wave reflector 28 helps to prevent standing waves and creates a uniform heating. During the process, at least during heating and curing of isocyanate for the polymerization to polyurethene plastic, harmful gases are produced which are removed via the outlet pipe 34. These gases can then be treated in a device connected to the outlet. The filter 33 prevents the spreading of microwaves to the surroundings.

Since the space in which the pane of glass is positioned is made as a relatively small gap in a conducting material, a highly effective utilization of the microwave effect is achieved. At the same time, the spreading of said gases are restricted to a small space and can thus be dealt with more easily than if they had mixed with a larger volume of air.

When using the device according to Fig. 5, polymerization occurs in the following way. As was described in connec¬ tion with the lid 26, the hood 50 is lowered over the product supported by the lower part of the device. As already described, the region which is to be treated is enclosed within the seals 61 and 62 together with the edge seal 63.

With the second embodiment according to Fig. 6, the method is carried out in an analogous way. The difference is solely that the microwaves must be supplied from two holes since the attachment 36 has two channels, and the microwaves from just one wave guide would be shielded by the shape of the attachment from spreading to more than one channel.

The invention has been described in connection with the affixing of metal attachments, such as aluminium, or plastic attachments to panes of glass. The attachment has been described particularly as having a channel surround- ing the edge of the pane of glass. This does not exclude the invention from being suitable for other applications in which the element which is to be affixed does not have such a shape, so long as it can be termed "an attach¬ ment". Materials other than metal or plastic can also be used for the attachment/element. It is also not necessary for the carrying out of the invention that the element to which an attachment is affixed is a pane of glass. A pre¬ requisite for the invention to be suitable is, however, that parts, two or more, need to be joined and which for their joining require heating but which are not suitable to be heated by anything other than microwaves to perform the joining process and thus of course glass is of great importance since it should not be heated to high temperatures and particularly not unevenly.