EP2084938B1 - Device for laying down a thin metal wire on a surface - Google Patents

Abstract

A device for laying a thin metal wire taken from a coil of wire stock onto a surface, in particular onto the surface of a sheet, using a presser. The device includes a mechanism exerting mechanical tension in a region of the wire that lies between the rotary coil of wire stock and the presser, and a wire-guiding device provided in the region. The wire-guiding device includes a tensioning device that acts directly on the wire taken off the coil of wire stock. That makes it possible effectively and appreciably to compensate for changes in relative speeds at which the wire and the sheet progress.

Description

The invention relates to a device for depositing a thin metal film on a surface and in particular on the surface of a sheet, which has the features of the preamble of claim 1. It relates in particular to the preparation of sheets of laminated glass heated by son.

Wire-meshed laminated glass panes are in particular window panes and the like which have a multilayer structure consisting of at least one rigid pane (glass or plastic) and a layer or sheet of synthetic material which adheres at its surface, several machine-deposited resistance wires being arranged in the boundary surface between the rigid pane and the layer or sheet of synthetic material. These wires are generally electrically connected in parallel and are supplied with heating voltage using at least two collectors. The collectors generally extend along each outer edge of the pane. In general, leaves equipped with wires are enclosed between two rigid panes.

The European patent EP 0 443 691 describes a device of this type, for depositing these son on sheets. It comprises a mobile laying device to which the son coming from a coil are brought via an eyelet guide and two toothed wheels which mesh with one another. The document DE 20 43 746 discloses such a wire laying device which has a wire guide tube disposed between the wire spool and the laying location.

The document DE 41 01 984 A1 discloses a similar device which has a simple guide between the wire spool and the gears. A Reducing transmission is provided between the gears and the driven roller steadily, which pushes the wires back onto the sheet. The gears rotate slightly slower than the push roller. This ensures that the corrugated wire always remains under a low tensile stress on the path that extends between the gears and the thrust roll. This prevents uncontrolled movement of the deposited wire.

In the document DE 42 01 620 A1 for such a device intended for laying wires in a straight line, which therefore does not have any means for waving the wires, an electric brake is provided on the wire reserve coil. The latter must maintain a constant tension in the unwound wire. On their path between the coil and the thrust roller, the son pass on rollers and guide rollers without braking function mounted on ball bearings.

Usually, the sheets to be provided with the wires in these known devices are attached to rotating drums which allow the sheet substrate to be fed more or less continuously beneath the wire laying devices. Depending on the local curve provided for the wires, the rotational movement of the drum can also be controlled at different speeds, so that braking or acceleration transitions are obtained.

When such a device is equipped with a braking system and waving mechanisms of the wire to be deposited, oscillations resulting from the deformation of the wire and the relative inertia of the wire reserve coil influence each other. and thus cause the formation of irregular ripples.

In addition, the ratio of the rotational speed of the wire spool and the rotational speed of the drum on which the PVB sheet to be provided with the threads is fixed is not constant. As a result, the pulling force under which the wire is pulled from the reel is not constant. There is therefore the need to keep the tension of the wire constant.

The problem underlying the invention is, for a device of the type indicated at the beginning, to further improve the guidance of the wire before laying on the sheet.

According to the invention, this problem is solved with the features of claim 1. The features of the dependent claims provide advantageous developments of the invention.

With the insertion of a clamping device or a clamping element into the path of the wire between the braided or non-braked wire stock coil, the desired improvement is achieved. The clamping element ensures a constant tension of the thread before the actual laying operation and possibly before it is corrugated. This greatly reduces the influence of a relatively slow rotation of the spool of stock, in any case when it is fully full, on the subsequent ripple and laying of the thread.

In other words, the yarn is passed into a "buffer zone" (for example with return rollers) to thereby compensate for the change in tensile force at the exit of the buffer zone by appropriate compensation of the force as well. only by compensation of the length of the wire inside the buffer zone.

This solution according to the invention has not been proposed so far by the state of the art, because basically, with the electric brake known, we could consider the problem of oscillations of the wire as resolved. The solution according to the document DE 20 43 746 mentioned above, which consists of passing the wire through a tube, could give no indication in this respect. The document does not disclose that it envisages that this guide tube has a braking effect. On the contrary, it assumes that the wire slides inside this tube with little friction.

Concrete possibilities of achieving the regulation of the tension of the yarn in the compensation part concerned include passive compensation by gravity-actuated mechanisms and active compensation by means of elastic elements, pneumatic cylinders or adjusting motors.

A yarn laying device thus equipped is equally suitable for conventionally laying yarns in a uniform manner, with or without corrugation, in regular courses, as well as for laying the yarn according to the paths recently proposed in any curves, in divergent courses. , in non-circular paths of variable radius, with local increases and / or decreases in wire laying density, etc. the clamping device according to the invention deploys its advantages particularly for the laying forms mentioned last, because in this case it is often necessary to order the sheet support at variable speeds. It is even possible (in a manner known per se) to make reversals of the direction of movement.

Other details and advantages of the object of the invention appear from the drawing of an exemplary embodiment of a wire laying device according to the present invention and its description given below.

• la figure 1 représente une vue globale du dispositif selon l'invention, avec un tambour de fixation du substrat en feuilles et un unique dispositif de pose de fil et
• la figure 2 représente une vue d'un dispositif de compensation de la tension du fil.

In simplified representations and not on scale:

• the figure 1 represents an overall view of the device according to the invention, with a fixing drum of the sheet substrate and a single wire laying device and
• the figure 2 represents a view of a device for compensating the tension of the thread.

The device according to the invention represented in the figure 1 comprises a drum 1 which forms, by means of a drive 2, a moving laying surface for thermoplastic sheets (in particular polyvinyl butyral). The sheets 3 with wires are generally placed between two rigid glass panes and / or synthetic material and connect them by adhesion over their entire surface, so that one thus obtains a laminated glazing which can be heated by means of sons.

The cylindrical drum 1 advantageously has a large diameter and a large circumference, so that one can put several sheets 3 on its cylindrical wall. We can see here two sheets 3 of the same size. They are fixed on the casing surface of the drum preferably by vacuum or pressure difference. For this purpose, the envelope surface is provided in known manner with a large number of bores through which the air is sucked. The atmospheric pressure pushes the leaves back onto the envelope surface.

Above the drum 1 is disposed a device 4 for laying the wire (also called the laying head). With a drive not shown in detail, this device can be moved back and forth parallel to the axis of rotation of the drum (and therefore parallel to the direction of examination of the figure) along a rectilinear guide 5. A wire 7 is extracted from a spare coil 6 of wire and is finally laid using a thrust roll 8 (preferably heatable) on the sheet 3 or incorporated in the surface thereof.

In the figure 1 it can be seen that the yarn is deposited continuously in successive loops, even on the edges of the sheet 3. It is obvious that these loops must be cut after laying the yarn and before the sheet 3 is removed from the drum 1 It is also obvious that on a drum 1, it is possible to use a plurality of wire laying devices located next to each other and synchronized.

The spool 6 of wire reserve can in known manner be equipped with a controllable brake, for example electric brake. The thrust roller 8 is preferably prestressed elastically against the casing surface of the drum 1 and rolls without proper drive on the sheet 3.

On the path between the wire reserve coil 6 and the thrust roller 8, the wire 7 passes through a guiding device generally indicated by 9 in the figure 1 . It serves firstly and in a known manner to impart a zigzag pattern or a waviness in the thread that passes through it. It is known that a zigzagging of the wires 7 minimizes their visibility in the finished laminated glazing (see in this connection the literature mentioned at the beginning).

In addition, the guiding device 9 has for the wire 7 which passes through it another clamping device whose figure 2 give more details.

For the sake of simplicity, this figure 2 represents in the same plane the entire guide device 9 and the path of the wire 7 between the wire reserve coil 6 and the thrust roller 8, because it is only to explain the operation and not to represent a real embodiment.

Similarly to the figure 1 , one can see a piece of a sheet 3 placed on the drum and the thread 7 which is unwound from the spool 6 of stock (being damped by the brake 6B known per se) and which is brought to the thrust roller 8 by the guide device 9, as indicated by several arrows in the course of the wire. On both sides of the thrust roll 9, the arrows show the instantaneous direction of advancement of the drum and the foil wrapping surface 3. When the thrust roll and the entire wire laying device are made of suitably, the direction of rotation of the drum can also be reversed to lay wires in more complicated paths and / or, when the drum is stopped, a wire can also be deposited by simple lateral movement of the laying device. thread.

Some lines of thread 7 'have already been placed on the sheet 3 by preceding rotation of the drum 1 and the thrust roll 8 must then be located so as to be able to put another line of thread 7' to its right. In an embodiment known per se, the thrust roller 8 has a flat and curved thrust surface. Thread 7 passes on the line of its summit. In this way, the thread 7 is pressed into the surface of the sheet 3 without the side edges of the thrust roll 8 penetrating the sheet 3.

The guiding device 9 comprises, in a manner known per se, two toothed wheels 10 which mesh with one another and which give the wire 7 guided between them the desired undulation immediately upstream of the thrust roll 8. To simplify the waviness of the wires laid on the sheet 3 has not been represented. With regard to the relative speed between the gears and the thrust roll, reference is made to in the state of the art described above.

According to the invention, starting from the wire reserve coil 6, and before entering between the gears 10, the wire 7 passes into a clamping device generally designated by 11. In its embodiment shown here, the latter comprises two fixed guide rollers 12 and between them, a clamping roll 13 movable and elastically prestressed. The latter is rotatably mounted in the clamping device 11 and / or in the guiding device 9 on an oscillating or pivoting lever 14 which itself is prestressed by means of a thrust spring 15. It is shown in broken lines. different possible positions of output of the pivoting lever 14 out of the central position shown in solid lines.

The guide rollers and the clamping roller can also be replaced by sliding guides if the wire can slide over them with negligible friction. They are not excluded, even if in the following we always talk about rollers.

Overall, the invention makes it possible to obtain a reaction as sensitive and as close as possible to the clamping device 11 to variations in the instantaneous tension of the thread. A particularly small mass of moving parts of the clamping device and low friction in all mounting locations and possibly slip can make a particularly interesting contribution in this regard.

It can be seen that between the two guide rollers 10, the wire 7 forms a U-shaped loop whose depth relative to the guide rollers 12 is defined by the effective position of the movable clamping roll 13 which is held under stress speak 15. This loop allows a fairly large compensation of the length, several centimeters, in the part of the wire which is at any time between the wire reserve coil 6 and the thrust roller 8.

If it is necessary to compensate for an even greater variation of the length, the clamping roller 13 (elastically prestressed) can also be guided in a straight line in an easily accessible sliding guide, in opposition to an elastic force or the like, instead of be by the pivoting lever shown, so as to extend over a greater length without angular offset.

On the whole, it is possible to compensate, in a very simple manner and with low inertia, variations in the speed of rotation of the drum 1 which result in an acceleration or slowing down of the rotation of the thrust roll 8 and consequently in general also an irregular consumption of thread. In particular, the mass of the wire reserve coil 6, which varies greatly depending on the reserve of wire still present, and the relative inertia of the brake 6B do not intervene in this compensation, which can therefore react very sensitive.

After the guide roller 12 located downstream in the direction of advancement of the wire, the wire 7 passes again between two guide rollers 16 which enter it exactly in the middle between the toothed wheels 10. These can obviously also be replaced by the sliding guide or even be completely removed if, starting from the second guide roller 12, the sufficiently accurate introduction of the wire 7 between the gears 10 is guaranteed.

It is obvious that any other embodiments of maintaining a voltage can be used. wire, even in these locations, provided that the conditions mentioned above (as well as the congestion data and the possibility of adjusting the wire tension) have the same effect. Thus, one could specifically provide a movable sliding rail instead of the clamping roller if it is expected that it will compensate for a difference in length too important. These sliding rails are known on chain or belt drives. They extend longitudinally in a curve whose radius of curvature changes as a function of the tension of the thread passing therethrough.

In addition, instead of the helical thrust spring 15 shown schematically here, it is also possible to use other adjustment means of the clamping roller 13, for example a pneumatic spring, a pneumatic adjustment drive, electrical or the like.

The clamping device may optionally also include a measuring unit (not shown here) which determines the effective tension of the thread which then imposes the necessary clamping force at all times on an associated setting drive. Such a measurement unit could for example detect the force exerted on its bearing by one of the return rollers 12, which force increases when the drum 1 accelerates and decreases when the drum 1 slows down. When the force on the wire is reduced, it will then be necessary to exert a complementary tightening, while in case of rise of the tensile force, the tension can be reduced.

Claims (14)

1. A device for laying onto a surface a thin metal wire (7) taken from a coil (6) of wire stock, in particular onto the surface of a sheet (3), using a presser (8), which device has means for exerting mechanical tension in that part of the wire (7) that lies between the coil (6) of wire stock and the presser, and a wire-guiding device (9) provided in this region, characterized in that the wire-guiding device (9) comprises a tensioning device (11) which acts directly on the wire (7) taken off the coil (6) of wire stock.
2. The device as claimed in claim 1, characterized in that the wire (7) is guided in the region of the tensioning device (11) over a portion of variable length.
3. The device as claimed in claim 2, characterized in that the variable length of the portion can be defined using at least one mobile tensioning roll (13) or a sliding part that has an equivalent function.
4. The device as claimed in one of the preceding claims, characterized in that the wire (7) is guided through the tensioning device (11) by, in turn, a first turn roll (12), a mobile tensioning roll (13) and another turn roll (12), or by corresponding sliding parts.
5. The device as claimed in one of the preceding claims, characterized in that the tensioning device (11) comprises a tensioning roll (13) or a sliding part that has an equivalent function and that is mounted on an elastically urged pivoting lever (14).
6. The device as claimed in one of the preceding claims, characterized in that the wire is guided through the tensioning device (11) by a mobile and preferably curved sliding rail.
7. The device as claimed in claim 3, characterized in that the tensioning roll (13) or the sliding part that has an equivalent function are mounted in a sliding guide.
8. The device as claimed in one of the preceding claims, characterized in that the tensioning device (11) comprises at least one spring (15) and/or a drive mechanism that is feedback controlled.
9. The device as claimed in one of the preceding claims, characterized in that the tensioning device (11) comprises a device for measuring the tension in the wire at any moment.
10. The device as claimed in one of the preceding claims, characterized in that a brake (6B), the braking force of which is preferably feedback controlled, is provided, so as to damp the rotational movement of the coil (6) of wire stock.
11. The device as claimed in one of the preceding claims, characterized in that means (10) are also provided for mechanically corrugating the wire (7) between the tensioning device (11) and the pusher (8).
12. The device as claimed in one of the preceding claims, characterized in that it comprises several laying devices as claimed in one of the preceding claims.
13. The device as claimed in one of the preceding claims, characterized in that the sheet (3) that is to be equipped with the wire (7) is fixed to a flat or curved laying surface, and in that the wire is laid down by relative movement of the pusher (8) and/or of the sheet (3), one relative to the other.
14. The device as claimed in one of the preceding claims, characterized in that a support element for supporting the sheet (3) can be moved reversibly with respect to the pusher (8).

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