Technical field of the invention

The present invention relates to the apparatuses for implementing composite materials, in particular with glassy matrices, for thermo-adjusting applications. The present invention, more in detail, relates to a device configured for implementing laminated glass boards, in particular in the automobile field, integrating filaments made of conducting material inside thereof.

Background

It is known using composite materials, especially with glassy matrices, in applications requiring to control the thermo-hygrometric properties of the environments, for example in building and automotive field.

Relatively to the latter, it is known to manufacture the crystals of the vehicles - the windscreens in particular - in layered glass, to provide them their own heating system, helping the visual task of the passengers by reducing the condensate phenomena in the interior.

Said windscreens structurally provide an intermediate layer made of polymeric material, comprised between two or more layers of glassy material, in which a grid of filaments made of conducting material is“drown”, almost invisible to the naked eye and crossed by electric current.

More in detail, the conducting material is deposited on the polymeric layer through dedicated application devices which arrange it by following specific orientations, typically according to predetermined waveforms, to reduce to the minimum unwished phenomena of optical distortion.

However, it is felt the need to improve said application devices, which have disadvantages in terms of control of adjustment of parameters for depositing the wire, thus penalizing the quality of the finished product.

Summary of the invention

The technical problem placed and solved by the present invention is then to overcome the above-illustrated problems, and this is obtained through a device configured to apply a wire on a substrate as defined in claim 1.

In particular, the object of the present invention is to provide a device configured to apply a wire on a substrate acting with high precision features.

An object of the present invention is also to provide a device configured to apply a wire on a substrate providing a high-quality finished product. Additional features of the present invention are defined in the corresponding depending claims.

The present invention relates to a device configured to apply a wire made of electrically conductive material on a substrate. Said device comprises a support unit having means for dragging the wire, which comprises at least a couple of wheels circumferentially provided with a plurality of deformation elements of the wire. In particular, said plurality of deformation elements is configured to contact the wire in a meshing region and, then, to deform it. The wire is deformed according to a predetermined waveform. The actuating means is configured to actuate said dragging means and it is connected to a control unit in turn connected to a detection unit. The device further provides means for depositing the wire, arranged downstream of said at least a couple of wheels with respect to a direction of advancement of the wire. Said detection unit is configured to detect at least one deformation parameter associated with the wire and the actuating means is configured to actuate the at least a couple of wheels depending upon the detected deformation parameter. The configuration of the device is so as to actuate said deposition means so that they apply adjacent tracts of wire arranged parallelly, each tract being deformed according to said predetermined waveform.

It will be appreciated that such solution advantageously allows to obtain a device which guarantees high flexibility in applying the wire on the substrate while maintaining extreme precision in the deposition. In fact, the proposed device allows to vary the relative distance of the couple of dragging wheels to vary the deformation extent of the wire, without the latter being subjected to unwished variations due to the clearance associated with the adjustment of the actuating means. According to an advantageous embodiment of the present invention, with respect to the known application devices, wherein the synchronous rotation of the deformation wheels is obtained mechanically through the use of toothed wheels which mesh therebetween, the proposed device provides an independent actuation of the deformation wheels so as to eliminate the clearance appearing upon varying the wheelbase therebetween when it is necessary to modify their mutual distance to change the deformation extent.

Such accuracy reflects as“phase” deposition of segments of wire. The device, in fact, in use is operatively associated with a rotating roller thereon the substrate configured to engage the wire is stretched which, once applied, results to be distributed according to a grid constituted by segments oriented parallelly therebetween, adjacent, preferably corrugated according to substantially sinusoidal or cosinusoidal waveforms.

Still, advantageously, the device comprises a detection system allowing both to return information about the quality of the performed deposition, and to intervene on the process parameters for a dynamic calibration thereof depending upon the production needs, practically configured to have information in real time allowing to perform a retroaction feedback based upon the detected parameters.

Other advantages, together with the features and the use modes of the present invention, will result evident from the following detailed description of preferred embodiments thereof, shown by way of example and not for limitative purposes.

Brief description of the figures

The drawings shown in the enclosed figures will be referred to, wherein:

- Figure 1 shows an overall perspective view of the device configured to apply a wire made of electrically conductive material on a substrate, according to a preferred embodiment of the present invention;

- Figure 2 shows a portion, in particular relating to the means for dragging the wire, of the device illustrated in Figure 1 ;

- Figure 3 shows a cutaway of a preferred embodiment of the means for adjusting the wire dragging means illustrated in Figure 2; and

- Figure 4 shows a perspective view related to a preferred embodiment of the actuating means of the device of Figure 1.

Detailed description of possible embodiments of the invention

The present invention will be described hereinafter by making reference to the above-mentioned figures.

By firstly referring to Figure 1 , a preferred embodiment of a device for applying a wire made of electrically conductive material, designated as a whole with the reference 100, is illustrated. Said device is intended to the use in the productive processes related to the manufacturing of composite materials, preferably in stations for the manufacturing of components for the automobile industry, in particular for manufacturing windscreens for vehicles, formed by a sandwich comprising glassy material and plastic material.

Still more preferably, the device, the present invention relates to, can be applied in the manufacturing of windscreens made of laminated glass or composite glass, wherein an intermediate layer made of plastic material, such as for example polyvinyl butyral (PVB), is interposed between one or more layers (or films) made of glassy material and it is configured to engage the wire made of electrically conductive material which remains“drown” therebetween. The wire, designated in Figure 2 with the reference F, suitable to be applied by the device 100, is preferably made of tungsten, and it allows the electrified heating of the windscreen to adjust the thermo-hygrometric conditions inside the vehicle’s interior.

Physical properties and dimensional features of wires of such type are known on themselves within the comprehension of the person skilled in the art and for this reason one will not further dwell thereabout hereinafter.

The device 100 according to the invention can also allow the manufacturing of products characterized by properties similar to the just mentioned ones, but intended to different uses, such as for example glasses in the building field or for architecture plans.

The device 100 is preferably configured to cooperate, under operating conditions, with an apparatus - not shown in figures - which receives a substrate thereon the wire F is deposited. As said the substrate is preferably made of plastic material and, for example, it can be received on the surface of a rotating roll placed in front of the device 100. A roll rotation offers substrate portions without wire F whereon the device 100 can perform the application, by typically allowing to implement a grid of filaments which result to be oriented parallelly therebetween.

It will be appreciated that the invention integrates in one single device an application unit and a system for controlling the process parameters, by determining advantageously an accurate parallel, preferably “in phase”, application of the waveform according thereto the segments of the deposited filiform material are deformed, as it will be described in greater detail hereinafter. The device 100, in general terms, is provided with means for adjusting the application speed, comprising a control element, for example a sensor, such as a dandy control designated with the reference 1 1. Such control element allows to adjust the speed for unwinding the wire F, for example depending upon the rotation speed of the roller which receives the substrate or predetermined parameters for tensioning the wire F which one wishes to set/maintain during application.

As it can be seen in figures, the device 100 comprises a support unit 10 having means 20 for dragging the wire comprising at least a couple of wheels 21 , 22 circumferentially provided with a plurality of deformation elements 23 of the wire. The wire F can be supported by the support unit 10 on one or more coils 12 thereon it is wound or even in remote position with respect to the device 100. The unwinding of the wire, in embodiments, can be assisted by unwinding means, such as motorized coils. The plurality of deformation elements 23 is configured to contact the wire F in a meshing region M and to deform it. The device 100, in substance, allows to keep aligned and tensioned the wire F until the latter reaches said couple of wheels 21 , 22 so that the deformation elements they comprise could deform it before it is deposited - according to a predetermined waveform - on the substrate.

A wire F applied on the substrate recti linearly, in fact, could produce tensions inside the glass so as to cause optical distortions. The wire F is then deformed, preferably according to a sinusoidal or cosinusoidal waveform, and applied corrugated in such way that unwished residual tensions do not appear in the final product.

The dragging means 20 comprises, as said, at least a couple of wheels 21 , 22. They support the deformation elements 23, implemented for example shaped like a pin or tooth, which can extend in an edge annular surface of the wheels 21 , 22 or even develop in an annular region which extends along an axial direction A from the edge annular surface.

According to a preferred embodiment of the present invention, the deformation elements 23 of a first wheel 21 , by rotating, occupy the free space between the deformation elements of a second wheel 22 of said at least a couple of wheels, in reality by implementing a kind of meshing“without contact” between the two wheels in the meshing region M. The first and the second wheel 21 , 22 have an opposite rotation direction and, preferably, the respective rotation axes A are parallel therebetween.

Each deformation element 23 is preferably implemented integrally with the respective wheel comprising it and it can provide a shape wherein three main portions can be identified. With reference to the embodiment example of Figure 3, a first elongated portion 23a extends from the wheel edge periphery as far as a second connection section, and a third portion 23c, with substantially circular shape, extends from the connection section to implement the free end of the deformation element 23. Each deformation element 23 of said plurality extends preferably along an axis orthogonal to the rotation plane of the couple of wheels 21 , 22.

Downstream of the couple of wheels 21 , 22, with respect to a direction of advancement of the wire F along the device, the latter comprises deposition means 90. The means 90 for depositing the wire F, illustrated as a way of example in figure 1 , 2 and 4 as a guiding roller, allows to approach and apply the deformed wire F to the substrate. In embodiments, the approaching is obtained through a relative motion of the device to the substrate, in such way that the wire F contacts the deposition means 90 and is subsequently applied. In other cases, the device and the substrate can be static and the deposition means 90 can be mobile so as to intercept the wire F outgoing from the couple of wheels 21 , 22 and to obtain subsequently the application on the substrate. By now referring to Figure 4, the device 100 further provides a control unit 40, or general control unit, connected both to actuating means 30, configured to actuate said dragging means 20 - in particular the couple of wheels 21 , 22 - and to a detection unit 50 configured to detect at least one deformation parameter associated with the wire F, better visible in Figure 1 , which will be described more in details hereinafter.

Preferably, the actuating means 30 is configured to actuate independently each wheel of said at least a couple of wheels 21 , 22 depending upon the deformation parameter detected by the detection unit 50. In substance, advantageously, the couple of wheels 21 , 22 rotate thanks to an independent, preferably synchronous, actuation so as to allow an adjustment of their wheelbase without such adjustment vitiating the precision of the waveforms wherein the wire F is deformed with the subsequent configurations of the dragging means 20. In this sense, the device 100 in fact comprises adjustment means configured to make relatively mobile therebetween said at least a couple of wheels 21 , 22 in a direction parallel with respect to their wheelbase.

The possibility of increasing or decreasing the wheelbase between the couple of wheels which deform the wire, through a synchronous and independent actuation thereof in rotation, overcomes the disadvantage of the known solutions which, by making use of a gear to transfer the motion from a driving wheel to a driven wheel, suffer from inevitably clearances due to the not perfect contact between the teeth.

In a preferred embodiment, by referring to Figure 3, the variation in the wheelbase between the couple of wheels is implemented by means of a mechanism which comprises a micrometric screw 13, the actuation thereof can be manual or even automatic. In this last case the adjustment means is connected to the control unit 40 to allow a combined control of the rotation synchronism of the wheels and their mutual distance, depending upon the deformation type to be obtained on the wire F. The means actuating the wheels 21 , 22, preferably, comprises independent brushless motors, each one connected to a respective local control unit. The above-said general control unit 40 thus controls the local control units and it is configured to allow a synchronization of the dragging means 20.

The dragging means 20, moreover, is further connected to the previously mentioned means 1 1 for adjusting the application speed, through the control unit 40. The device 100 is configured, or rather, to deform the wire F preferably depending upon its tensioning, upon its speed in advancing on the support unit or upon the application speed, the latter for example parameterised depending upon the apparatus receiving the substrate.

In order to ease the advancement of the wire F, a guide element, designated in Figure 3 with the reference 60, can further be provided. Said element, in the illustrated embodiment, is a substantially plate-like element provided with a rectilinear groove 61 configured to receive the wire F inside thereof. The groove allows to keep the wire aligned before the latter engages the meshing region M defined by the dragging means 20. Such plate-like element can have a groove 61 with dimensions in the order of size of ten of millimetres, for example about 25 mm, and it is preferably positioned upstream of said at least a couple of wheels 21 , 22 with respect to the direction of advancement of the wire F.

The wire F, during application, is preferably deformed more than it results once it has been applied on the substrate. In this sense, the device 100 applies a slight tension as, advantageously, this facilitates to keep the wire inside the guiding element 60 and with respect to a predetermined position of application on the substrate. Such tensioning is obtained through an adjustment of one or more control parameters performed by the control unit 40 which, by controlling the synchronous rotation speed of the couple of wheels 21 , 22, allows the wire to outgo from the meshing region M with a slower advancement speed with respect to the speed with which it results to be applied on the substrate.

Going back to Figure 2, the device 100 further comprises a heating unit of the wire configured to heat it by means of heat conveying means and/or electrical induction means. In the illustrated embodiment, the heating unit provides the heating of the wire through the synergic use of a heated roller 70, thereon the wire slides by heating upon contact, and an electric power supply allowing the circulation in the wire of a current through the application of a potential difference, for example in the order of a couple of volts, in the segment of wire comprised between the heated roller 70 and the couple of wheels 21 , 22.

A heating of the wire F providing the combined use of the above-mentioned systems allows the device 100 to apply the wire with higher speeds, for example up to 200 metres/minute, and at lower temperatures, lower than 200°C and preferably comprised about 100°C, with respect to the known solutions, by reducing among other things stress phenomena on the substrate which, preferably as said being made of plastic material, is not likely to receive the wire at high temperatures.

In each case, advantageously, the control unit 40 is configured to allow an adjustment of the parameters, for example the temperature of the heated roller 70 and the applied potential difference, associated with the heating unit, and programmable with a control panel by an operator.

Preferably, the support unit 10 comprises a cutting unit 80 configured to cut the wire F once the application has ended and to start again with a subsequent application. In the illustrated example, the cutting unit 80 comprises a locking - or pinching - component which locks the advancement of the wire and a properly cutting, preferably electrical, component, for example in the form of two claws having different potentials. The cutting unit 80 is preferably positioned downstream of the heating unit, in particular downstream of the heated roller 70.

As said, the device 100 comprises a detection unit 50, visible in Figure 1 , and carried by the support unit 10. In the illustrated embodiment, the detection unit 50 is mounted on a bracket 50a and comprises detection sensor means 51 , preferably a detection optical unit, such as for example a camcorder or a camera, projected on the application region of the wire and associated with a lighting source of the substrate, the latter apt to light in a diffused way said application region. Under lighting source herein even sources emitting radiation in the not visible spectrum are meant.

The above-mentioned detection unit can be for example a matrix camera, used for detections in linear form. In this case, it is configured to acquire data like a sequence of lines detected at a determined frequency, to acquire the parameters associated with the waveform of the applied wire.

The deformation parameters of the wire F detected by the detection unit 50 are preferably the wavelength, wave amplitude, the pitch (that is the distance between adjacent wires) and/or the phase of the waveform of a segment of wire with respect to a previously applied corresponding segment. In particular, two or more segments of wire result to be“in phase” therebetween if each crest and belly of the respective waveforms can be wholly overlapped, in translation, along a direction orthogonal to the respective pivoting axes, that is without width and phase differences. Generally, the device 100 is then configured to actuate the deposition means 90 in such way that they apply adjacent segments of wire arranged parallelly, each segment being deformed according to the predetermined waveform. In preferred embodiments, the device 100 is configured in such way that said adjacent and parallel segments of deformed wire reproduce said predetermined waveform with a predetermined phase difference or, preferably, in“phase” therebetween, as described above.

In other embodiments, the detection unit 50 could provide sensor means 51 comprising photodiodes or similar technologies, but in each case configured to obtain real time information allowing to perform a retroaction feedback in based upon the detected and acquired parameters.

The control unit 40 then processes the acquisitions of the detection unit 50, for example based upon an analysis performed in the frequency domain through the Fourier transform, by comparing the wire application parameters with the set reference parameters, to check the congruity thereof. According to such check, the control unit 40 then controls the various units of the device 100, in particular the actuating means 30, the means 1 1 for adjusting the application speed, the means 70 for heating the wire.

_★★★ A preferred mode of a method for analysing the application parameters of two adjacent segments of wire F, applied on the substrate and detected by the detection unit 50, will be now described, by way of not exhaustive example.

The control unit determines a matrix associated with an image F acquired by the detection unit 50 at a detection area of the substrate wherein two segments of wire, adjacent therebetween, are applied. Preferably, the detection unit 50 acquires at a frequency of 30 kFIz, with an exposition time equal to 20 ps and a gain equal to 8. The image F is composed for example of a plurality of horizontal lines which are acquired every 1/30000 of second. Said plurality of lines represents a plurality of line vector Fi and are pre-processed as described hereinafter.

Each line vector Fi of the matrix is standardized by subtracting its average value and by dividing by the standard deviation. The so-obtained new vector F’i is multiplied by the factor -1. Subsequently, the values of the vector F’i are modified by replacing with the value zero (0) the values of the vector F’i lower than 2.5, by obtaining the vector Fk.

The peak values of the vector Fk are identified which correspond to the instantaneous position of two segments of wire applied adjacent on the substrate.

The position (as a function of time) of the couple of peaks is reproduced on a cartesian reference system through a “peak detector” function (or common analogous function in codes specialized in analysing the signals). The set of the positions of the couple of peaks represents the waveforms of the two adjacent segments of wire.

Through an interpolation or algorithms of patern recognition the best fit of said set of positions and thus a continuous waveform is obtained. By using additional algorithms of pattern recognition, it is subsequently possible to calculate even the frequency, the width and the phase of the obtained continuous waveforms. In this sense, a plurality of sinusoids at different frequencies is produced and afterwards a cross-correlation is performed between said sinusoids and the waveforms obtained by analysing the images.

The cross-correlation assumes a maximum value when the generated sinusoid and the obtained waveform can be substantially overlapped. In this way it is possible to determine which one of the generated sinusoids better approximates the waveform. Of said generated sinusoid, then, all features are known, that is phase, width and frequency which will correspond to the features of the waveforms associated with the image F acquired by the detection unit 50.

_★★★

The proposed invention, then, implements in reality an automatic control integrated system through which the device 100 is capable of evaluating in real time the quality of the process for applying the wire and to detect the position of possible differences or defects, being able to correct potentially the same dynamically during the application itself. In reality a systematic quality control is obtained before the assembly of the finished product, by reducing advantageously waste material. An additional advantage lies in the fact that it is possible a more accurate setting of the machine by the operator who can intervene on the defects no more based upon his/her own sensibility but upon the parameters detected by the quality control system.

The device 100 is, advantageously, capable of performing an automatic control on the width and length of the waveform of the applied wire, parameters of significant relevance especially in the processes for manufacturing components made of laminated glass in applications for automotive fields, where the accurate “phasing” of the waveform in the grid constituted by the tracts of deposited wires parallelly on the substrate is quality index of the final product. The present invention has been sofar described with reference to preferred embodiments thereof. It is to be meant that each one of the technical solutions implemented in the preferred embodiments, herein described by way of example, can advantageously be combined, differently from what described, with the other ones, to create additional embodiments, belonging to the same inventive core and however all within the protective scope of the herebelow reported claims.