EP0823531A2 - Method and device for applying a spacer of plastic material onto a glass panel - Google Patents

Abstract

The method involves using and applicator with a nozzle (17) which is moved around the edge of the glass pane (33) to apply the strand of plastics so that the beginning and the end of the strand join together. A film (45) is applied over a length (l) of the glass pane and the thickness of the strand (35) by discharging from the nozzle over a line with a predetermined length (L), rising from the thickness of the film to a set thickness (D). At the end of the strand the surface (36) thickness tapers from this set thickness down to zero. The applicator comprises a nozzle, the mouth (24) of which has a virtually rectangular cross-section and is closable by a slide (26). A first drive is provided for operating the slide and a second drive moves the nozzle in one plane.

Description

The invention is based on a method for applying a strand a plastic substance on a glass sheet to form a spacer with a predetermined target thickness for an insulating glass pane using a nozzle, which is moved around the edge of the glass sheet around it and thereby deposits the strand emerging from the nozzle on the glass sheet so that the beginning and collide the end of the strand by the thickness of the strand as it exits from the nozzle at the beginning on a route of a predetermined length of Increased zero to the target thickness and complementary to it at the end of the strand is reduced from the target thickness to zero on the same route. Such a process is known from WO 96/09456. According to the known method the plastic strand is extruded and placed on the glass panel in such a way that the beginning and do not collide bluntly at the end of the strand, but over one Inclined surface, which is at an angle other than 90 ° to the plane of the Glass panel runs. The process is carried out using a nozzle, the Exit cross section is changeable by a slide and completely closed and that while moving along the glass panel is, can also be lifted from this. Between the beginning and end of the Strangs creates a joint in the known way of working, which during assembly and then pressing the insulating glass pane under pressure is set. This will make the two at the beginning and end of the strand formed inclined surfaces pressed against each other and stick together tightly. However, there is a problem area at the top of the at the beginning of the Strand formed inclined surface: The angle between the glass plate and the The tip of the sloping surface at the beginning of the strand must be made of the plastic substance be filled in completely at the end of the strand. If that doesn't work then remains in the area of the joint between the glass sheet and the extruded Spacer a - albeit extremely fine channel, which through the subsequent sealing of the edge joint of the insulating glass pane is covered, nevertheless, it facilitates the diffusion of water vapor The weak point of the seal is and shorten the life of the insulating glass pane can.

The invention has for its object to provide a measure with which the emergence of such a weak point in the seal of insulating glass panes, the plastic spacer of which is formed according to the method mentioned above, can be counteracted.

This object is achieved by a method with those specified in claim 1 Features and by a device with the in claim 8 specified features. Advantageous developments of the invention are the subject of the dependent claims.

To the angle between the glass sheet and the top of the sloping surface of the plastic To be able to fill the strand with the plastic substance, if the nozzle at the end of its orbit around the glass top of the tip already on it deposited strand again, the substance would have to be sufficiently high Pressure can be injected into this angle. However, this is difficult because the mouth of the nozzle lies in a plane perpendicular to the plane of the glass sheet, to with the nozzle, which is perpendicular to the glass sheet lying in this plane Axis is rotatable, uninterruptedly extrude a perfectly shaped corner to be able to. The consequence of this is that the strand is parallel or at most emerges at an acute angle to the glass panel and only with slight pressure on the Glass panel meets. It is therefore difficult to wedge-shaped at the top of the initial Section of the plastic strand in the flow shadow of out of the nozzle emerging material lying angle between the tip and the glass sheet fill completely with the plastic material when the nozzle at the end of its Circulation around the glass panel returns to the beginning of the strand. Remains there is a gap, even if it is only a narrow capillary, then unfortunately you can do not expect that during the subsequent pressing of the insulating glass pane, in which the plastic spacer is compressed, in each Case disappears. The cohesion prevailing in the spacer causes that despite the pressing, the plastic material in the border area to the Glass sheet on which it was extruded, no longer or hardly flows, especially since if it is hot after application (as with thermoplastic Polyisobutylene is common) cooled in contact with the cold glass sheet and solidified.

According to the invention, these problems are countered by using the nozzle first apply a film of plastic substance with a certain length and only then proceed as described in the WO 96/09456 was disclosed by following the application of the film the thickness of the strand as it exits the nozzle along a predetermined path Length L from the thickness of the film based on the target thickness D of Strand increased and complementary to it at the end of the strand on the same Distance L is reduced from the target thickness D to zero, which is due to progressive Closing the nozzle is achievable.

At the beginning of the strand, the tip continues in a film. Of the Transition from this film to the bevel at the beginning of the strand takes place by the progressive opening of those moving along the glass panel No abrupt, but flowing nozzle and can when extruding the end of the Strands covered by the pasty substance much more easily and completely are called the transition from the bevel at the top of the strand to the Glass sheet in the prior art according to WO 96/09456. At the top of the Films are the geometric conditions for an absolutely tight connection the end of the strand with the glass sheet much cheaper than in the prior art at the tip of the strand delimited by an inclined surface, namely around the cheaper the thinner the film that is applied to the glass sheet. Advantageously, the film is preferably not more than 0.3 mm thick applied in a thickness of only 0.1mm to 0.2mm. The minimum thickness The film should be sized so that the film is uninterrupted can be applied.

The length of the film is not particularly critical. With a film, which some is a few centimeters long, you will reach your goal. A length of the Films from 0.5cm to 1cm.

When the bevel is formed at the end of the strand and at the beginning of the strand formed beveled at the beginning and end of the To connect the strands tightly together, then it is not necessary to end up of the strand formed inclined surface to continue in a film the strand already lying on the glass panel would be laid. On this from the The glass panel facing away from the connection of the beginning and end of the strand is the probability that between the strand and the second one to be added Glass panel remains a channel facilitating water vapor diffusion, extraordinarily low because the pressing of the second glass sheet is immediate affects the adjacent surface of the strand and becomes a uninterrupted connection with the second glass panel leads, in contrast to the adhesive surface between the opposite first glass sheet and the strand, which can no longer be influenced to the extent by pressing the second glass sheet is like the adhesive surface between the strand and the second glass sheet. But it is quite possible, even when closing the nozzle, a thin, short one Form film, which is placed on the strand already formed and with is pressed against him.

From WO 96/09456 it is already known that it is advantageous to use the top of the strand, which is glued to the second glass sheet, slightly convex to train. This allows air pockets in the adhesive surface when Avoid pressing with the second glass sheet.

Instead, an opposite measure is preferred on the underside of the strand, by designing the contour of the mouth of the nozzle so that the Strand with a slightly concave underside applied to the first glass sheet becomes. Unexpectedly, it has been shown that this results in an optimal Adhesion of the strand can be achieved on the first glass sheet. This is because that in the plastic material, especially if it is a polyisobutylene acts, there are internal tensions that tend to be convex sprayed surface to bend more or a surface that has just been sprayed to bend. The internal tensions in the plastic material tend to to reduce the curvature of a slightly concavely sprayed surface, so that by relieving the internal stresses to a flat surface can be what is optimal for the adhesion on the first glass sheet and - if how it is preferred to work with approximately vertically arranged glass panels - a tilting of the strand from the glass sheet due to gravity countered effectively.

The nozzle known from WO 96/09456 is used to carry out the method suitable. To a film from the plastic substance on the glass panel to apply, the nozzle is first opened only a narrow gap in order to afterwards, if a film of about 5 mm to a maximum of a few cm in length on the Glass panel has been applied by pressing the slider steadily up to to open the desired cross-section of the mouth.

It is more advantageous to use a nozzle that compared to that from WO 96/09456 known nozzle is modified in that it is not only the Direction of movement of the second drive is oriented opposite, but additionally with a smaller part of its mouth that level the glass sheet on which the strand is to be applied is facing. A such a nozzle has the advantage that the one that forms when opening Gap facing the glass sheet, so that the plastic emerging from the gap Material with much higher pressure hits the glass sheet than with an im flow direction of the tangential to the glass sheet surface Substance. With the new nozzle it is therefore achieved that the initially formed one Film connects perfectly to the glass sheet surface, without air connections and capillaries through which water vapor could otherwise diffuse later. The new nozzle has proven itself not only when applying the film, but also when applying the strand over its entire length, because even if the slider opens further to the strand in its desired cross-section to be applied to the glass sheet has the direction of flow of the substance from the Mouth of the nozzle out a stronger component towards the glass sheet than in the case of the nozzle known from WO 96/09456, so that the quality the overall adhesion of the strand to the glass sheet is improved.

Measured in the direction of movement of the second drive of the nozzle section of the mouth directed against the glass panel expediently via no more than 3mm in length, preferably no more than 2mm in length. With such a limitation of what is directed against the glass sheet Part of the cross-section of the mouth is still excellent corner formation achieve if you move the nozzle around the corners of the glass sheet pivoted to this vertical axis, which in the flat, larger part the mouth should lie, which is the direction of movement of the second drive the nozzle is oriented in the opposite direction.

The side walls delimiting the mouth of the nozzle expediently extend perpendicular to the plane in which the glass sheet is located up to Bottom of the nozzle so that the thickness of the film is not towards its two edges increases. Preferably the thickness of the film tends towards both of its edges from.

In order to achieve a film that is as thin and closed as possible, the Part of the mouth of the nozzle facing the glass plate is parallel to the glass plate Have edge, however, the bottom of the nozzle with the rest of the glass panel one acute angle should include the application of the end portion of the Strand towards the inclined surface of the beginning section of the strand facilitate.

The wall at the tip of the slide, which when closing the nozzle in the the part of the mouth facing the glass panel dips, closes with the glass panel preferably one in the direction of movement of the second drive of the nozzle opening acute angle. The advantage of this measure is that this wall at the top of the slider when applying the film like one Spatula acts, which presses the film onto the glass panel. A convenient angle for this task is 4 °.

The smaller part of the mouth, which faces the glass sheet to be coated is through a recess in the bottom of the nozzle, but also through a Recess be formed at the tip of the slide, which only then takes effect when the slide is pulled back a little. The two Measures can also be combined with one another. The recess is located in the bottom of the nozzle, this has the advantage that you can Extrude the strand over its entire length to a higher pressure the glass panel brings. If you provide the recess in the slider, then it has the advantage that the course of the strand when forming corners by turning the nozzle around an axis perpendicular to the glass sheet and lying in the mouth is cheaper.

Instead of moving the nozzle along a stationary glass sheet, you can also use the Let the nozzle rest and instead move the glass plate along the nozzle. These two types of movement can also be combined with each other

Figur 1

zeigt einen Längsschnitt durch eine Düse zum Auftragen eines plastischen Strangs auf eine Glastafel,

Figur 2

zeigt die Ansicht II der Düse aus Figur 1,

Figur 3

zeigt als vergrößertes Detail einen Schnitt durch die Spitze der Düse aus Figur 1,

Figur 4

zeigt die Ansicht auf die Unterseite der Düse gemäß Figur 3,

Figur 5

zeigt die Ansicht V der Düse gemäß Figur 3, die

Figuren 6 - 9

zeigen in vereinfachtem Längsschnitt die Düse in verschiedenen Arbeitsphasen, die

Figuren 10-12

zeigen eine zweite Ausführungsform der Düse in Darstellungen entsprechend den Figuren 3 bis 5,

Figur 13

zeigt eine dritte Ausführungsform der Düse in einer Darstellung entsprechend der Figur 3,

Figur 14

zeigt den Querschnitt XIV - XIV durch die Düse in Figur 13, die

Figuren 15-18

zeigen in einem vereinfachten Längsschnitt die Düse aus den Figuren 13 und 14 in unterschiedlichen Arbeitsphasen entsprechend den Figuren 6 bis 9,

Figur 19

zeigt eine erfindungsgemäße Vorrichtung mit einer der vorstehend dargestellten Düsen in der Vorderansicht,

Figur 20

zeigt dieselbe Vorrichtung in einer teilweise geschnittenen Seitenansicht,

Figur 21

zeigt einen Längsschnitt durch eine Düse gemäß dem Stand der Technik,

Figur 22

zeigt die Verbindungsstelle zwischen Anfang und Ende des Strangs in einem plastischen Abstandhalter für Isolierglas, und

Figur 23

zeigt als Detail aus Figur 22 die für die Dichtheit einer Isolierglasscheibe kritische Stelle in einem plastischen Abstandhalter.

Embodiments of the invention are shown schematically in the accompanying drawings. Identical or corresponding parts are identified in the various examples with the same reference numbers.

Figure 1

shows a longitudinal section through a nozzle for applying a plastic strand on a glass sheet,

Figure 2

shows the view II of the nozzle from Figure 1,

Figure 3

shows an enlarged detail a section through the tip of the nozzle from Figure 1,

Figure 4

shows the view of the underside of the nozzle according to Figure 3,

Figure 5

shows the view V of the nozzle of Figure 3, the

Figures 6 - 9

show in simplified longitudinal section the nozzle in different working phases, the

Figures 10-12

show a second embodiment of the nozzle in representations corresponding to Figures 3 to 5,

Figure 13

shows a third embodiment of the nozzle in a representation corresponding to Figure 3,

Figure 14

shows the cross section XIV - XIV through the nozzle in Figure 13, the

Figures 15-18

show in a simplified longitudinal section the nozzle from FIGS. 13 and 14 in different working phases corresponding to FIGS. 6 to 9,

Figure 19

shows a device according to the invention with one of the nozzles shown above in front view,

Figure 20

shows the same device in a partially sectioned side view,

Figure 21

shows a longitudinal section through a nozzle according to the prior art,

Figure 22

shows the connection between the beginning and end of the strand in a plastic spacer for insulating glass, and

Figure 23

shows as a detail from FIG. 22 the point critical for the tightness of an insulating glass pane in a plastic spacer.

The device shown in FIGS. 19 to 21 is from WO 96/09456 known and can in its basic structure also for the purposes of the present Invention can be used.

The device has a carrier 1, which extends along a traverse 2 by a Drive 3 is displaceable perpendicular to the plane of Figure 20. The traverse itself is parallel to a plane 4, in which the surface during machining a glass panel lies, displaceable at right angles to the longitudinal extent of the cross member 2. On the carrier 1, a block 5 is also attached, which of a Rotating cylinder 6 around a plane parallel to plane 4 in the drawing plane of FIG. 20 lying axis 7 displaceable and by an electric motor 8 and a spindle 9 existing drive is displaceable perpendicular to level 4. Around this movement to a controllable extent and at a controllable speed To be able to perform, the motor 8 with a rotor position and speed sensor 10 connected.

The block 5 carries two alternately operated refillable piston-cylinder units 11 and 12 for the intermediate storage and delivery of the plastic substance, from which spacers are to be formed. The piston-cylinder units 11 and 12 are each with a level indicator 13, 14 with limit switch equipped. The two piston-cylinder units 11 and 12 are based a common valve block 15, in which a heated pressure hose 16 flows through which the cylinders are supplied with the plastic substance. In the valve block 15 there is a rotary valve which alternately one piston-cylinder unit 11 or 12 with the pressure hose 16 and the other Piston-cylinder unit 12 or 11 connects to a nozzle 17.

The nozzle 17 is located at the tip of a hollow nozzle shaft 18, which is rotatably mounted in a holder 19 in which a known per se Rotary coupling that is pressed out by one of the piston-cylinder units 11, 12 plastic material gets into the hollow nozzle shaft 18.

For rotating the nozzle shaft 18 in its holder 19, a rotary drive is on the block 5 20 with slip ring transmitter 21 and rotor position and tachometer encoder 22 appropriate.

The nozzle 17 has a bottom 23 which is inclined to the plane 4 and which is pointed approaches and immediately a mouth 24 oriented perpendicular to the plane 4 Nozzle limited. The mouth 24 has a substantially rectangular Cross-section. The axis of rotation 25 of the nozzle shaft 18 runs in the middle of the mouth perpendicular to level 4.

To close the mouth 24, a slide 26 is provided, which can be replaced between a wall 27 of the nozzle shaft running parallel to the axis 25 and a removable counter-holder 28 is arranged. Between the Wall 27 and the counter-holder 28, the slide 26 can be moved parallel to the axis 25 guided. In order to be able to move it, it is toothed 29 provided, which meshes with a pinion 30, which by a on the nozzle shaft 18 attached, small electric motor 31 can be driven in a controlled manner. The Slider position can be influenced by a potentiometer 32.

The electric motor 31 and the motor 8 are electronic with each other synchronized.

To describe the operation of the device, reference is made to FIG taken:

A glass sheet 33 on which a plastic strand 35 is applied as a spacer is to be located in level 4. The nozzle 17 is passed through the glass sheet Actuation of the motor 8 is delivered, the slide 26 initially in its Closed position. The nozzle is then moved along the crosshead 2 and / or by moving the cross member 2 parallel to the glass sheet 33 in the direction of the arrow 34 moves in a direction opposite to the mouth 24. In The start phase of the movement is the slider over a distance of length L. 26 open continuously until it reaches a predetermined position in which the off the strand 35 emerging from the nozzle 17 has reached its target thickness D. Because of the steady Opening the slide 26 receives the strand 35 in the start phase on the Distance L a steadily increasing thickness, so that the top of the strand there is formed by an inclined surface 36.

The nozzle 17 is now guided parallel to the glass sheet 33 along its edge around it and lay a strand of constant cross section and constant thickness D from the glass sheet 33. Finally the nozzle approaches 17 back to their starting position. She continues unchanged until she is with her Bottom edge 37 reaches the tip 38 of the start portion of the strand 35. Because of the oblique course of the bottom 23 of the nozzle, the angle of which is somewhat larger is chosen as the angle of the inclined surface 36 with the glass sheet 33, it comes not to a flat contact of the bottom 23 with the inclined surface 36. Im further course of the movement of the nozzle 17 in the direction of arrow 34 is the Nozzle now controlled by operating the motor 8 so that their Lower edge 37 moved along the inclined surface 36. Simultaneously and in sync with it the slider 26 is continuously advanced; he closes the mouth when the Lower edge 37 of the nozzle has reached the upper edge 39 of the inclined surface 36 (Figure 22). In this way, a wedge-shaped end portion 40 of the strand formed, which is complementary to the initial portion of the strand is and lies on it.

A critical point for the tightness of the insulating glass pane lies at the tip 38 the inclined surface 36, where a difficult to close capillary between the tip 38, the opposite end section 40 and the glass sheet 33 occur can. The occurrence of such a capillary can be prevented according to the invention trained nozzle can be effectively countered.

In the case of the nozzle 17 shown in FIGS. 1 and 2, in which the channel 41, through which the plastic material flows to the mouth 24 to form a end portion 42 directed obliquely against the glass sheet 33 in contrast to 21 is angled, at the tip of the slide 26 is a small, but important recess 43 is provided, which is clearer in the figures 3 and 4 is shown. The recess 43 is very narrow and so in height small that when the slide 26 is closed - shown in broken lines in FIG. 3 - is completely covered by the bottom 23 of the nozzle, so that in the closed position of the slide also through the recess 43 no material can leak. However, if the slide 26 is raised slightly from the floor 23, then there is a connection with a columnar cross section from End portion 42 of the channel into the recess 43 so that through the recess 43 a thin film of the plastic material against the plane 4 directed, in which the glass sheet 33 is located, can emerge. The cross-sectional shape The recess 43 can be seen in FIG. 4: The recess 43 is in the Cross-section a circular section of low height, so that the thickness of the formed Film decreases from the center of the film to both of its edges.

At a short distance from the mouth 24, the bottom 23 is curved 44 provided, which is effective when the slider 26 is raised so far is that not only a film is formed through the recess 43 becomes. The curvature 44 has the effect that the strand 35 on its the glass sheet 33 facing side emerges slightly concave and then under the effect internal material tensions fully and fully connects with the glass sheet 33.

The operation of the nozzle according to the invention is shown in Figures 6 to 9. FIG. 6 shows the nozzle 17 delivered to a glass sheet 33 before the start of the Applying the plastic substance; the slide 26 holds the nozzle 17 completely closed. With the start of the movement of the nozzle 17 along the glass sheet 33 in Direction of arrow 34 (or in the case of a stationary nozzle 17 when moving the Glass plate 33 in a direction opposite the arrow direction 34) Slider 26 initially only opened so little that the plastic material only can emerge through the recess 43. This position of the slide is for a distance of the nozzle 17, which is preferably only 0.5 cm to at most a few cm is maintained. The direction of flow of the material is perpendicular against the glass plate directed and causes good adhesion of the film 45 on the Glass panel 33 (Figure 7). If the film 45 has reached the desired length, the Slider progressively removed from the bottom 23, causing a wedge-shaped rising Initial portion of the strand 35 is formed with an inclined surface 36 will (Figure 8). If the desired height D of the strand 35 has been reached (FIG. 9), the slide 26 remains in its position and the strand 35 is along the Edge of the glass sheet 33 applied to this until the nozzle 17 the beginning section with the inclined surface 36 approaches. Before the sloping surface reaches 36 the strand 35 is placed on the film 45, with which it is sealed connects. The beginning and end of the line are then connected lengthways the inclined surface 36, as previously described with reference to FIG 22. Different than in the prior art, where the danger at the tip 38 of the inclined surface 36 there was a leak, such a danger is eliminated by the invention, because the tip of the inclined surface 36 continues into the thin film 45. At the The tip of the thin film 45 are the prerequisites for a seamless connection with the strand 35 lying thereon much better than in the state of Technology.

The exemplary embodiment of the invention shown in FIGS. 10 to 12 differs differs from the embodiment shown in Figures 3 to 5 in that the recess 43 is not provided in the slider 26 but in the bottom 23 is. In this case, the recess 43 can be closed by one on the Inside the slide formed step 46, the inclination with the inclination of the bottom 23 matches and in the closed position of the slide 26 the recess 43 covered. The operation of this nozzle corresponds to the operation the nozzle from Figures 3 to 5; refer to FIGS. 6 to 9 referred.

The third embodiment of the invention shown in FIGS. 13 and 14 differs from the second embodiment in that the recess 43 in the bottom 23 of the nozzle has larger dimensions than in the exemplary embodiment 10 to 12: The recess 43 extends in the direction of movement 34 of the nozzle 17 over a length of 2mm to 3mm. To close them to be able to, the slide 26 has an inward extension 47 with a stage 46, which on the floor 23 with the slide 26 closed Edge of the recess 43 sits. At the tip of the slider 26 is an inclined surface 48 formed, which is inclined weaker relative to the glass sheet 33 than the bottom 23, preferably an angle of 4 ° with respect to the glass sheet 33 and when applying the film 45 acts as a spatula, the film additionally presses on the glass panel 33.

A further inclined surface 49 is provided in the bottom 23 at the edge of the recess 43, which has a smooth transition from the bottom 23 into the recess 43 allows. The sloping surface 49 lies opposite the slide 26 with its Extension 47 and forces the material flowing to the mouth 24 to change the flow direction in the direction of the recess 43. The plastic material therefore occurs not only when applying the film 45, but also when applying of the strand 35 with a movement component directed against the glass sheet 33 out of the nozzle 17 and thus adheres better to the Glass board 33.

FIGS. 15 to 18 show the working phases for the nozzle from FIGS. 13 and 14 corresponding to FIGS. 6 to 9.

In all exemplary embodiments, the axis of rotation 25 of the nozzle is perpendicular runs to the glass panel 33, in the plane of the main part 24 of the mouth, which, as in the prior art, opposes the direction of movement 34 is so that a spacer with perfectly contoured corners is uninterrupted can be extruded. The side walls 50 of the nozzle, which limit their mouth laterally, initially run vertically with their edge 51 to the glass panel 33 and then parallel to the glass panel 33. The invention provided additional mouth cross-section formed by the recess 43 is directed exclusively against the glass panel 33.

Claims (17)

Method for applying a strand (35) made of a plastic substance onto a glass sheet (33) to form a spacer with a predetermined target thickness D for an insulating glass pane with the aid of a nozzle (17) which is moved around the edge of the glass sheet (33) and thereby places the strand emerging from the nozzle (17) on the glass sheet (33) such that the beginning and end of the strand (35) collide, by first using the nozzle (17) to apply a film (45) of the plastic substance over a length (l) to the glass sheet (33) and then the thickness of the strand (35) as it emerges from the nozzle (17) over a distance with a predetermined length L increased from the thickness of the film (45) to the target thickness D and complementary to it at the end of the strand (35) over the inclined surface (36) formed at the beginning of the strand from the target thickness D back to zero. Method according to claim 1, characterized in that the film (45) is not made thicker than 0.3 mm. Method according to Claim 2, characterized in that the film (45) is made 0.1 mm to 0.2 mm thick. Method according to one of the preceding claims, characterized in that the film (45) is no more than a few cm long. A method according to claim 4, characterized in that the film (45) is 0.5cm to 1cm long. Method according to one of the preceding claims, characterized in that the strand (35) is shaped by the nozzle (17) in such a way that when it emerges from the nozzle (17) its surface, which faces the glass sheet (33), onto which the Strand (35) is placed, is slightly concave. A method according to claim 6, characterized in that the opposite surface of the strand (35) is shaped slightly convex. Device for carrying out the method according to one of the preceding claims, with a nozzle (17), the mouth (24) of which has an approximately rectangular cross section and can be closed by a slide (26), with a first drive (31) for actuating the slide (26), with a second drive (3) for moving the nozzle (17) in one plane (4), and with a third drive (8) for moving the nozzle (17) transversely to that plane (4), the mouth (24) of the nozzle (17) being oriented essentially opposite to the direction of movement (34) of the second drive (3),
characterized in that the mouth (24) of the nozzle (17) at its end closest to that plane (4), hereinafter referred to as the bottom (23) of the nozzle, additionally with a smaller part (43) of its cross-section of that plane ( 4) is facing. Apparatus according to claim 8, characterized in that the mouth (24) of the nozzle (17) is delimited by side walls (50), the edges (51) of which extend at right angles to that plane (4) to the bottom (23). Apparatus according to claim 8 or 9, characterized in that the bottom (23) with that plane (4) includes a first acute angle which opens in the direction of movement (34) of the second drive (3), but that of the plane (4th ) facing part (43) of the mouth (24) has an edge parallel to the plane (4). Device according to one of claims 8 to 10, characterized in that the wall (48) at the tip of the slide (26) which, when the nozzle (17) closes, into the part (43) of the mouth (43) facing the plane (4) 24) plunges, with the plane (4) enclosing a second acute angle that opens in the direction of movement (34) of the second drive (3). Device according to claim 11, characterized in that the second acute angle is 4 °. Device according to one of claims 8 to 12, characterized in that the side walls (50) delimiting the main part (24) of the mouth of the nozzle (17) form a flat edge (51) of the main part (24) of the mouth and that the nozzle ( 17) can be rotated about an axis (25) running perpendicular to that plane (4) and lying in the flat main part (24) of the mouth. Device according to one of claims 8 to 13, characterized in that the base (23) of the nozzle (17) is convex inward in the vicinity of its mouth (24). Device according to one of claims 8 to 14, characterized in that the smaller part (43) of the mouth facing that plane (4) of the mouth extends in the direction of movement (34) of the second drive (3) by no more than 3 mm, preferably 2 mm. Device according to one of claims 8 to 15, characterized in that the part (43) of the mouth of the nozzle (17) facing that plane (4) is formed by a recess provided in the base (23) of the nozzle (17). Device according to one of Claims 8 to 16, characterized in that that part (43) of the mouth of the nozzle (17) which faces that plane (4) is formed by a recess provided at the tip of the slide (26).

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