Method and system for quality control of a winding of at least one strip of material for the production of electrical energy storage devices

Abstract

A method and system for quality control of a winding (2) of at least one strip (3, 4) of material for the production of electrical energy storage devices around a winding axis (A); the winding (2) has two base surfaces (9, 10) opposite to each other and transverse to the winding axis (A) and a lateral surface (11) joining the base surfaces (9, 10); the method includes an acquisition step, wherein at least one image of the strip (3, 4) comprising at least part of the lateral surface (11) of the winding (2) is acquired by means of at least one sensor (12); a processing step, wherein the image is processed to control the quality of the winding (2) and at least one measurement value relating to an axial position and / or an axial dimension of an element (20) of thestrip (3, 4) is determined as a function of the image; the quality of the winding (2) is controlled as a function of the measurement value.

Description

[0001] "METHOD AND SYSTEM FOR QUALITY CONTROL OF A WINDING OF AT LEAST ONE STRIP OF MATERIAL FOR THE PRODUCTION OF ELECTRICAL ENERGY STORAGE DEVICES"

[0002] Cross-Reference to Related Applications

[0003] This Patent Appl ication claims priority from Italian Patent Applications No . 102023000023076 and No . 102023000023067 both filed on November 2 , 2023 , the entire disclosure of which is incorporated herein by reference .

[0004] Technical Sector

[0005] This invention relates to a method and system for quality control of a winding of at least one strip of material for the production of electrical energy storage devices . In particular, this invention relates to a method and system for controlling the alignment of one or more electrode strips used for the production of electrical energy storage devices , and to a corresponding automatic machine for the production of said electrical energy storage devices equipped with said system .

[0006] In particular, this invention finds advantageous , but not exclusive , application in the production of cylindrical electrical energy storage devices or, in any case , ones provided with windings ( such as , for example , cylindrical rechargeable batteries or cylindrical capacitors ) to which the following description will make explicit reference without any loss of generality thereby .

[0007] State of the Art

[0008] Automatic machines are known for the production of electrical energy storage devices , in particular cylindrical rechargeable batteries or cylindrical capacitors . The automatic machines known for the production of cylindrical batteries feed and convey electrode and separator strips along several feeding paths , all of which converge towards a rotating winding unit ( also known as a "winding plug" ) typically cylindrical , which is configured to hold and wind the electrode strips (with positive and negative polarity - cathode and anode ) and separator strips overlapping each other in a separator-electrode-separator- electrode pattern to form a cylindrical winding . In particular, the separator layer is designed to prevent short circuits and, in particular, to become soaked with an electrolyte , so as to form a winding, usually cylindrical , also known as a " Jelly-Roll" .

[0009] More speci fically, automatic battery production machines comprise a feeding unit with as many coils as there are electrode strips and separator strips to feed and convey the electrode strips and separator strips along their respective feeding paths .

[0010] Usually, however, electrode strips consist of a metal core ( or current collector ) made of aluminium or copper, which is partially covered by a known coating not described further, but cons isting mainly of highly compressed powders ( e . g . graphite for the anode ) . Due to the high compressions and inherent errors in the production of the coils , they usually exhibit imperfections ( e . g . an accentuated camber ) . For these reasons , systems known as "web guiders" have been developed over the years , but they are only able to roughly compensate for imperfections , focusing on compensating for the average of the errors present on the coils ( or generated by some misalignment of the machine ) . Therefore , although by using such devices the average error value is reduced, it is not accurately compensated for, neglecting undesirable fluctuations in error (e.g. around the mean value) that worsen the quality of the battery, as they cause misalignments in the overlapping of the electrodes.

[0011] In addition, during supply to the winding core, the electrode strips are respectively subjected to extreme accelerations in the case of high production speeds. Therefore, also due to the high handling speeds of the apparatus conveying the electrode strips to the core, misalignments between the two electrode strips, e.g. due to the aforementioned errors or tolerances (or camber or any other error determined during the production of the same or the assembly of the support rollers of the automatic machine along the conveying paths) of the electrode strip coils, lead to misalignment errors, i.e. linear or angular deviations (rotations) between strips of material. These deviations result in a loss of quality and thus battery performance. Moreover, these deviations, which are essentially random if the average error is already compensated for by a web-guiding system, are also the cause of some ams or machine stoppages that slow production down at least partially and lower the efficiency of the automatic machine .

[0012] There is, therefore, a need to improve the quality and thus the performance of the battery. In particular, there is a need to reduce errors in aligning the strips that form the winding .

[0013] Object and Summary of the Invention

[0014] The purpose of this invention is to provide a method and system for quality control of a winding of at least one strip of material for the production of electrical energy storage devices , which are at least partially free of the drawbacks described above and, at the same time , are easy and inexpensive to manufacture .

[0015] In accordance with this invention, a method and system for quality control of a winding of at least one strip of material for the production of electrical energy storage devices are provided .

[0016] The claims describe preferred embodiments of this invention forming an integral part of this description .

[0017] Brief Description of the Drawings

[0018] In order to better understand this invention, a nonlimiting preferred embodiment thereof will now be described by way of example with reference to the accompanying drawings , in which :

[0019] - Figure 1 is a schematic side view, with parts removed for clarity, of an automatic machine for the production of electrical energy storage devices made according to an embodiment of this invention;

[0020] - Figure 2 is a perspective and schematic view (with some parts removed for clarity) of the automatic machine in Figure 1 according to an additional , alternative embodiment of this invention;

[0021] - Figures 3 and 4 are perspective views , with parts removed for clarity, of two di f ferent embodiments of a machine part from Figure 1 during the formation of a winding of strips of material for the production of electrical energy storage devices ;

[0022] Figure 5 is a front view, on an enlarged scale, of the winding in Figures 3 and 4 ;

[0023] - Figure 6 is a schematic view of the winding in Figure 5 , in the presence and absence of material strip alignment errors ;

[0024] - Figure 7 illustrates a diagram of the architecture of a control system, in particular of an arti ficial intelligence algorithm, implemented by a control unit of the machine in Figure 1 and / or 2 ;

[0025] - Figures 8 and 9 illustrate part of the architectural diagram of part of Figure 7 according to two di f ferent examples of use ; and

[0026] - Figure 10 is a schematic view of the winding in Figures 5 and 6 , showing the overlapping between the material strips forming the winding .

[0027] Detailed Description

[0028] In Figure 1 , reference number 1 indicates , as a whole , an automatic machine for the production of electrical energy storage devices .

[0029] In detail , the automatic machine 1 is configured to produce windings 2 from at least one strip 3 , 4 of material suitable for the production of electrical energy storage devices .

[0030] In particular, the machine 1 is configured to produce windings 2 from electrode strips 3 and separator strips 4 suitable for the production of electrical energy storage devices .

[0031] In particular, in the embodiment illustrated, the machine 1 is configured to produce windings 2 from two electrode strips 3 ( one cathode strip and one anode strip ) and two separator strips 4 . More speci fically, the machine 1 is configured to produce cylindrical windings 2 , to which the description will make explicit reference , without any loss of generality thereby, or flattened ones ( e . g . wound on a flat plug) .

[0032] In light of the foregoing, this invention finds advantageous but not exclusive application in the production of capacitors or rechargeable batteries , more speci fically in the production of cylindrical or oval rechargeable batteries comprising cylindrical or oval windings 2 , to which the following description will make explicit reference without any loss of generality thereby .

[0033] Rechargeable batteries comprise two electrode layers ( cathode and anode ) and at least two separator layers arranged of fset from each other in an alternating electrodeseparator-elect rode -separator pattern .

[0034] These layers are obtained from the aforementioned continuous strips 3 , 4 , which are cut to predetermined lengths to form a sequence of windings 2 .

[0035] In this regard, the machine 1 comprises a winding apparatus 5 configured to wind electrode strips 3 and separator strips 4 onto themselves to form the aforementioned winding 2 sequence .

[0036] These windings 2 are then arranged, during a known process , downstream of the apparatus 5 , inside containers or "cans" (usually metal ) , which, in the case of conventional batteries , are then filled with an electrolyte to form a respective rechargeable "j elly roll" battery ( in the case of solid-state batteries , the electrolyte is instead integrated into the winding and integral with the separator strips ) .

[0037] Therefore , in this case , the apparatus 5 is used to wind two electrode strips 3 , a cathode and an anode , and two separator strips 4 arranged of fset from each other according to the aforementioned alternating pattern, so as to form a battery or capacitor, or more speci fically a battery module or capacitor unit of a capacitor .

[0038] As can be seen in Figure 1 , the apparatus 5 ( and, thus , the machine 1 ) comprises :

[0039] - a winding core ( or plug) 6 revolving around a winding axis A, configured to grasp strips 3 , 4 and rotatable to drag the grasped strips 3 , 4 and thus form a winding 2 ;

[0040] - a feeding unit 7 configured to feed strips 3 , 4 to the winding core 6 along respective distinct feeding paths P ; and

[0041] - a system 8 for the quality control of the winding 2 .

[0042] In the non-limiting embodiment illustrated, as best shown by Figure 5 , each winding 2 formed is a cylindrical winding having a first base surface 9 and a second base surface 10 opposite each other and transverse to the winding axis A and a lateral surface 11 j oining the base surfaces 9 , 10 together .

[0043] The feeding unit 7 preferably comprises a plurality of support shafts or spindles each designed to support a respective coil 30 , 30 ' of strip 3 , 4 in a rotatable manner .

[0044] The winding core 6 is of a known type and generally consists of a bar formed by two elongated elements rotating around the winding axis A configured to hold the strips 4 in a grip between them, so as to be able to rotate them and determine the progressive formation of the winding 2 around the axis A ( then wedging the strips 3 between the two strips 4 already partially wound) . In use, each strip 3, 4 is unwound from its respective coil 30, 30' along its feeding path P to the winding core 6. The latter, once the strips 3, 4 have been grasped, is rotated around its own axis A, causing the strips 3, 4 to be dragged or pulled (so they unwind) from the coils 30, 30' .

[0045] Conveniently, according to the non-limiting embodiment illustrated by Figure 1, the feeding unit 7 feeds, in use, a first electrode strip 3 (e.g. the cathode) in a position between the two separator strips 4.

[0046] More specifically, the feeding path P of the cathode 3 lies between the feeding paths P of the separators 4.

[0047] Conveniently, the feeding path P of the other electrode strip 3 (e.g. the anode) is positioned in such a way that the anode strip 3 itself overlaps the separator strip 4 radially inwards with respect to the winding 2.

[0048] In this way, the cathode strip 3 is fed to the winding core 6 already interposed between the two initially spacedapart separator strips 4, so as to obtain the aforementioned alternating electrode-separator-electrode-separator pattern (specifically, anode-separator-cathode-separator) .

[0049] The strips 3, 4, i.e. the feeding paths P, all converge at the winding core 6.

[0050] Conveniently, the machine 1 also comprises guide components 14, pliers 15, and cutting devices 16, 16' the operation of which is known, e.g. from patent application No. IT102021000021314, in the name of the Applicant itself, and, therefore, will not be described in detail. Briefly: the guide components 14 are each configured to grasp a respective electrode strip 3 and advance it towards the core 6 at the feed rate of the strip, so as to avoid unwanted stretching or tensioning at the beginning of each winding; the pliers 15 are designed to grasp the respective strips 3 , 4 to facilitate their being cut ; and the cutting devices 16 , 16 ' are configured to cut the strips 3 , 4 to a certain length, once the des ired size o f the winding 2 has been reached .

[0051] As illustrated by Figure 1 , the apparatus 5 preferably comprises a winding station B defining a convergence end of the feeding paths P and at which a winding 2 is cyclically formed by rotationally driving the winding core 6 .

[0052] In accordance with what has j ust been described, the core 6 is mobile between the winding station B, where it receives the strips 3 , 4 and winds them as explained above to form one winding 2 at a time , a closing station C, where said winding 2 is closed by a closing device (not illustrated) , and an unloading station D, where an unloading assembly (not illustrated) unloads the formed and closed winding 2 .

[0053] For this purpose , the apparatus 5 comprises a handling device , in particular a rotating platform, even more speci fically a star wheel 17 that can rotate about a rotation axis AS , preferably parallel to the axis A of the core 6 , and configured to sequentially move the core 6 between the winding station B, the closing station C, the unloading station D, and, again, the winding station B .

[0054] In the illustrated embodiment , the apparatus 5 comprises a plurality of winding cores 6 ; in particular, the apparatus 5 comprises three cores 6 carried by the wheel 17 and spaced equally apart around the rotation axis AS thereof so that each occupies one of the three stations B, C or D . As already mentioned, the machine 1 includes a system 8 for the quality control of a winding . The system 8 comprises at least one sensor 12 configured to acquire at least one image of the at least one strip 3 , 4 , and a control unit 13 configured to process the at least one image to control the quality of the winding 2 .

[0055] The sensor 12 is arranged such that the at least one image comprises at least part of the lateral surface 11 of the winding 2 .

[0056] According to the non-limiting embodiment illustrated in Figure 3 , the sensor 12 is arranged so as to acquire an image comprising the entirety of the lateral surface 11 of the winding 2 ; in other words , the sensor 12 has a field of view, identi fied schematically in Figure 3 by the proj ection of the cone CP, which comprises the entirety of the lateral surface 11 of the winding 2 .

[0057] In other non-limiting embodiments , the sensor 12 is arranged so as to acquire a partial image of the lateral surface 11 of the winding 2 . In particular, the partial image comprises either an axial portion, or a radial portion of the lateral surface 11 , which comprise at least one end 28 of the winding 2 .

[0058] In the non-limiting embodiment in Figure 1 , the sensor 12 is arranged downstream of the cutting device 16 for the electrode strip 3 .

[0059] According to another, non-limiting and non-illustrated embodiment , the sensor 12 is arranged upstream of the cutting device 16 for the electrode strip 3 ; in particular, the sensor 12 is arranged between the cutting device 16 ' and the cutting device 16 . According to other embodiments not illustrated above , the sensor 12 has di f ferent arrangements from those illustrated above , as long as these arrangements allow at least part of the lateral surface 11 of the winding 2 to be acquired .

[0060] The control unit 13 is configured to determine , as a function of the at least one image , at least one first measurement value relating to an axial position and / or an axial dimension of a first element 20 of the at least one strip 3 , 4 on the surface of a portion of winding 2 already formed and at least one second measurement value relating to an axial position and / or dimension of the second element 20 ' of the at least one strip 3 , 4 entering the winding 2 . The control unit 13 i s configured to control the quality of the winding 2 as a function of the at least one first measurement value and of the at least one second measurement value .

[0061] The control unit 13 actually interacts with the sensor 12 to receive the image acquired by the sensor 12 . In particular, the control unit 13 communicates with the sensor 12 in a wireless or wired mode .

[0062] In some , non-limiting examples , the system 8 comprises two distinct sensors 12 ' and 12 ' ’ configured to acquire two distinct images comprising, each, at least one respective end 28 of the winding 2 .

[0063] In particular, according to the non-limiting embodiment illustrated in Figure 4 , the two distinct sensors 12 ' , 12 ' ' are side-by-side and each has a distinct field of view, identi fied schematically in Figure 3 by the proj ection of the cones CP . The fields of view of the sensors 12 ' , 12 ' ' each comprise a substantially equal axial portion of the lateral surface 11 of the winding 2 . Each axial portion comprises a distinct end 28 of the winding 2 . In particular, the entirety of the fields of view of the two sensors 12 ' , 12 ' ' comprises the entirety of the lateral surface 11 of the winding 2 .

[0064] According to additional embodiments not illustrated, the fields of view of the two sensors 12 ' , 12 ' ' do not comprise the entirety of the lateral surface 11 , but only an axial or radial portion of it .

[0065] According to additional embodiments , the number of sensors used is more than two . These sensors are side-by- side and / or overlap each other .

[0066] In accordance with another non-limiting embodiment that is not illustrated, the system 8 comprises two distinct sensors 12 ' , 12 ' ' , one upstream and one downstream of the cutting device 16 , respectively .

[0067] Preferably, but without imposing limits , the sensor 12 is a camera and / or video camera comprising a telecentric lens .

[0068] The use of a telecentric lens finds advantageous application in quality control as it neutralises perspective ef fects due to inaccurate positioning or pronounced three- dimensionality, ensuring accurate measurements from the acquired image . In particular, the main problem generated by classic lenses lies in the variation in diameter of the winding 2 during winding, which al so leads to a variation in the perspective position of the strips 3 and 4 .

[0069] In particular, the camera and / or video camera includes a lighting system, e . g . a lamp . Alternatively, the lighting system is not included in the camera and / or video camera, but is, for example, an external system. Such a lighting system ensures optimal conditions for image acquisition and thus optimum performance of the quality control system 8. In particular, the lighting system is configured in such a way as to achieve uniform lighting of the winding 2.

[0070] In accordance with additional non-limiting embodiments, the sensor 12 is an optical sensor of another kind, operating in the visible or infrared or ultraviolet spectrum, in particular, but without imposing limits, a colour and / or linear one.

[0071] In general, the sensor 12 (or sensors 12', 12' ' ) is arranged so that there is no obstacle between the sensor 12 and the winding core 6.

[0072] Advantageously but without imposing limits, the machine 1 comprises at least one additional control system 8' arranged upstream of the at least one winding core 6 at the coil 30 of the at least one strip 3. The control system 8' is configured to acquire at least one image of the at least one strip 3 to determine a width measurement of the at least one strip 3.

[0073] As illustrated by the non-limiting embodiment in Figure 2, the system 8' comprises two sensors 18, 18' respectively arranged at the coils 30 of the feeding unit 7, which unwind the electrode strips 3.

[0074] According to additional embodiments not illustrated, the sensors 18, 18' are arranged at the coils 30' that unwind the separator strips 4. Thus, since the separator strips 4 are partially covered during winding around the core 6, their position (along the winding axis A) can be checked in advance. In particular, advantageously but without imposing limits, a feedforward estimator is used to measure the so- called "separator overhang", i.e. the extent of the overlap between the separator strip 4 and the electrode strip 3. In particular, the separator overhang on the anode and / or cathode strip can be measured.

[0075] According to other embodiments not illustrated, the system 8' comprises a single sensor 18, 18' or more than two sensors. According to other embodiments not illustrated, the sensor 18, 18' is arranged at all the coils 30, 30' provided in the feeding system 7.

[0076] In detail, the presence of the system 8' allows the quality of the coil 30, 30' of strip to be checked before the winding operation, i.e. before the winding 2 is formed on the core 6. Thus, if the material of the coil 30, 30' does not conform, i.e. the width of the strip 3, 4 is incompatible with the manufacturing tolerances allowed in the production process, the coil 30, 30' can be discarded and replaced.

[0077] In particular, the presence of the systems 8', 18', and possibly other similar systems on the separator strips 4, allows feedforward control of the position of the strips 3, 4 on the winding core 6, so as to compensate for any viewing difficulties (e.g. of the coating in transparency under a separator strip 4) on the part of the sensor 12 in viewing all the strips.

[0078] Advantageously but without imposing limits, the control unit 13 is configured to receive the width measurement of the at least one strip 3, 4 and use it as a reference to determine the at least one measurement value, depending on the image acquired by the sensor 12. In particular, as described below, the control unit 13 is configured to control the correction of the position of at least one of the strips 3 , 4 as a function of the at least one measurement value ( in particular according to known control methods , for example feedback or by means of estimators , in particular in feedforward) .

[0079] In accordance with another aspect of this invention, a method for quality control of a winding 2 of at least one strip 3 , 4 of material for the production of electrical energy storage devices around a winding axis A is provided .

[0080] The method comprises : an acquisition step, in which at least one image of the at least one strip 3 , 4 i s acquired by means of at least one sensor 12 ; a processing step, in which the at least one image is processed to check the quality of the winding 2 . The image comprises at least part of the lateral surface 11 of the winding 2 .

[0081] During the processing step, as a function of the at least one image , at least one first measurement value is calculated relating to an axial position and / or an axial dimension of a first element 20 of the at least one strip 3 , 4 on the surface of a portion of winding 2 already formed and at least one second measurement value relating to an axial position and / or dimension of a second element 20 ' of the at least one strip 3 , 4 of material entering the winding 2 . An axial position and / or dimension is defined as a position and / or dimension that extends in the direction defined by the winding axis A of the core 6 , i . e . along the longitudinal axis of the winding 2 .

[0082] The quality of the winding 2 is controlled according to at least one first measurement value and at least one second measurement value.

[0083] Advantageously but without imposing limits, in some cases, with reference to Figure 5, the first element (20) and the second element (20' ) comprise at least one edge. The first measurement value and the second measurement value are determined according to the respective edge. In particular, the term edge means an edge and / or an end (outer) portion of a strip of material 3, 4 or a component thereof that forms (helps form) the winding 2.

[0084] Thus, the measurement value determined indicates the alignment of an incoming portion in the winding 2 with respect to an already formed portion of winding 2. In other words, the measurement value, which defines the quality of the winding, is preferably determined by comparison between a given portion of winding 2 and the subsequent portion of winding 2, taking, for example, the first portion wound on the core 6 at the beginning of the winding process as the reference .

[0085] Preferably but without imposing limits, alternatively or additionally, the first element 20 and / or the second element 20' are / is a strip 3, 4 of material, more specifically, according to a preferred but not limiting embodiment, the strip 3, 4 of material is the electrode strip 3.

[0086] Preferably, but without imposing limits, the first element 20 is a first electrode strip 3' and the second element 20' is a second electrode strip 3' ' that is different to the first strip 3' .

[0087] With reference to Figure 5, considering the anode strip 3' (or possibly the cathode strip) as the element 20, three edges 21, 22, 23 are identified within the element 20. In particular, the edge 21 and the other edge 23 define the ends of the strip 3', while the edge 22 defines the boundary between the uncoated ("bare foil") portion 24 and the coated portion 25 of the strip 3.

[0088] Theoretically, it is possible to identify for each electrode strip 3 (anode and / or cathode) (at least) three distinct edges (corresponding to the three edges mentioned above for the anode strip 3' ) and, thus, it is possible to determine, by processing the image, the three positions of these edges. In practical terms, depending on the arrangement of the sensor 12 with respect to the strips 3, 4, only some of these edges are visible in the captured image.

[0089] According to additional embodiments, by using appropriate sensors 12 it is also possible to detect strip edges in transparency, i.e. strip edges that are not in the foreground of the acquired image, but are, for instance, covered by other strips (in particular a separator 4) .

[0090] As an example, Figure 5 illustrates an image that can be obtained during the acquisition step by arranging a single sensor 12 as in Figures 1 and 2, i.e. just after the cutting device 16. In the non-limiting case illustrated, the entirety of the edges 21, 22, 23 of the electrode strip 3', i.e. the anode, is visible; in contrast, the electrode strip 3' ', i.e. the cathode, is only partially visible. In particular, it is only possible to detect the edge 26 that constitutes an outer edge of the strip 3' ' , specifically, of its uncoated portion .

[0091] According to an additional, non-limiting embodiment, the element 20 is a separator strip 4. In this case, depending on the arrangement of the sensor 12 , one of the outer edges of the separator strip 4 can be detected from the acquired image . For example , with reference to Figure 5 , the edge 27 of the strip 4 is visible .

[0092] Preferably, considering the aforementioned separator overhang, it is possible to determine for each electrode strip 3 ' , 3 ' ' a measure of the overlap between the separator 4 and the respective strip 3 ' , 3 ' ' .

[0093] In particular, with reference to Figure 10 , it is possible to determine , for the anode strip 3 ' the extent of the overlap between the bare foil 24 and separator strip 4 as the distance between the edge 22 of the anode strip 3 ' ( that defines the separation between the coated and uncoated area of the strip 3 ' ) and the edge 29 of the separator strip 4 .

[0094] Alternatively or additionally, the measurement of the overlap between the separator 4 and the coated portion of the anode strip 3 ' can be determined as the distance between the edge 22 and the outer edge 33 of the cathode strip 3 ' ' .

[0095] In the same way, alternatively or in addition, it is possible to determine , for the cathode strip 3 ' ' the extent of the overlap between the bare foil 34 and separator strip 4 as the distance between the edge 36 of the cathode strip 3 ' ' ( that defines the separation between the coated and uncoated area of the strip 3 ' ' ) and the outer edge 27 of the separator strip 4 .

[0096] Alternatively or additionally, the measurement of the total overlap between the separator 4 and the anode strip 3 ' ' can be determined as the distance between the outer edge 27 of the separator 4 and the outer edge 23 of the anode strip 3 ' .

[0097] Based on the measurements mentioned above, the measurement of the overlap between the separator 4 and the coated portion of the anode strip 3' ', i.e. the distance between the edge 36 and the outer edge 23 of the anode strip 3', can be determined. This last measurement value can be determined independently of the others. Similarly, it is possible to determine a different combination of the above- mentioned measurement values and then derive one or more further dependent measurement values. For example, it is also possible to derive the total overlap between the separator strip 4 and the anode strip 3', i.e. the distance between the edge 29 and the other edge 33, from the above measurements .

[0098] In particular, and without limits, with reference to Figure 10, the measurement value relates to the so-called " telescopicity" of the winding 2. "Telescopicity" is a defect that can occur in strip windings (coils) when, during a single winding, the strip translates (shifts) sideways, protruding from the already formed winding, or retracting from the already formed winding, compromising the quality of the coil.

[0099] In detail, it is possible to determine the total telescopicity of the winding 2 from the measurement of the distance between the edges 21 and 26 of anode and cathode strips 3' and 3' ’ respectively. By comparing this value, obtained for each individual winding turn, with the value of the average height of the winding 2, the telescopicity values of the cathode 3' ' and anode 3' can be defined.

[0100] Preferably but without imposing limits, the image comprises a longitudinal portion of the lateral surface 11 extending from the first base surface 9 to the second base surface 10 of the winding 2.

[0101] According to the non-limiting embodiment illustrated in Figure 5, the image includes a front view of the entire winding core 6 and, consequently, both base surfaces 9, 10. The image also comprises the entire length of the lateral surface 11 of the winding 2, as well as a portion of the strips 3, 4 before winding on the core 6 (i.e. coming into the core 6 itself) .

[0102] Advantageously, according to a non-limiting embodiment, two distinct images are acquired by means of two distinct sensors 12' , 12' ' , wherein the distinct images each comprise a respective end 28 of the winding 2. In other words, the two distinct images each comprise at least one base surface 9; 10 of the winding 2.

[0103] In other words, in fact, the areas of interest for the determination of the measurement value are located near the base surfaces 9, 10 of the winding 2, i.e. near the ends 28 of the winding; therefore, it is also possible to determine the measurement value from two distinct images each relating to one distinct end 28 of the winding 2 or from a single partial image comprising at least one end 28 of the winding 2. This improves the accuracy and resolution of the measurement, reducing the small distortions normally caused by detections in peripheral areas in the field of view of the sensors 12.

[0104] Preferably but without imposing limits, the acquisition step is performed during the winding of the strip 3, 4, particularly when the winding speed of the strip 3, 4 is constant .

[0105] Furthermore, according to a preferred but non-limiting embodiment, the acquisition step is performed multiple times during the winding of the strip 3, 4 around the winding axis A; in particular, the number of times is defined according to a length of the strip 3, 4.

[0106] In other words, it is possible, given the length of the winding 2, i.e. the strips 3, 4 that make up the winding 2, to define an optimal number of images to be made that allow sufficient data to be collected to perform the quality control of the winding 2. This number is preferably determined empirically and, if reduced, simplifies the image processing performed by the control unit 13. Preferably, but without imposing limits, this number is equal to the number of complete turns made by the winding core 6.

[0107] Advantageously, according to further and non-limiting embodiments, the acquisition can be a film taken by a video camera from which frames are extracted, subsequently processed by the control unit 13 to determine the measurement value .

[0108] As an example, considering a winding 2 with a length of 2000 mm, an image is made every 2 mm, thus obtaining 1000 images in total. If a camera is used, this results in the acquisition of 1,000 photographs, while in the case of a video camera, the same number of frames is extracted from the captured footage.

[0109] According to another non-limiting embodiment, the acquisition step is performed whenever a (complete) winding of the strip 3, 4 on the winding core occurs. In other words, the sensor 12 is a camera that captures an image every complete rotation of the core 6 around its axis A, i.e. every 360° rotated.

[0110] Preferably but without imposing limits, the acquisition step comprises two sub-steps: a first acquisition sub-step, in which a reference image is def ined / acquired; and a second acquisition sub-step, in which the image to be processed is acquired to extract the measurement value. During the processing step, the at least one measurement value is determined by comparing the image acquired with the reference image .

[0111] In particular, the measurement value is determined as a deviation between the position of the first element (20) and / or of the second element (20' ) in the reference image and the position of the first element (20) and / or of the second element ( 20 ’ ) in the at least one acquired image; more specifically, during the processing step, it is verified that the deviation is within a predefined acceptability range; in particular, the acceptability range is from -1 mm to 1 mm, more particularly from -0.3 mm to 0.3 mm, preferably from -0.1 mm to 0.1 mm.

[0112] By way of example, considering the previously discussed example of Figure 5, in which the element 20 is the electrode strip 3', i.e. the anode strip 3', in the first acquisition sub-step the reference image is obtained / def ined from which the position of the outer edge 21 of the strip 3', for example, is determined. Hereinafter, in the second acquisition sub-step, I obtain an image from which I determine the position of the same outer edge 21. At this point, I determine the deviation between the two determined positions; this deviation constitutes the measurement value. Therefore , depending on the si ze of the deviation, the quality of winding 2 is defined . In other words , by comparing each image acquired during the second acquisition sub-step with the reference image , it is possible to monitor the alignment of the strip 3 ' throughout the winding on the core 6 .

[0113] According to some non-limiting embodiments , the reference image is updated, i . e . changes over time , as the winding is formed . In particular, the acquired image replaces the reference image .

[0114] In other non-limiting examples , the reference image is acquired by the control unit 13 from a special memory and is therefore not detected in the moment by the sensor 12 .

[0115] The processing step preferably comprises two sub-steps : a determination sub-step, in which the actual distance between the first base surface 9 and the second base surface 10 is determined; and a comparison sub-step, in which the actual distance is compared with a predefined ideal width of the winding 2 .

[0116] In addition to checking the alignment of the strips during winding, it is also possible to check the width of the winding 2 ( i . e . the distance between the bases 9 and 10 ) . Basically, considering that the winding, as already mentioned above , once formed, is discharged at the station D and placed in a container ("can" ) , it must have a desired width (within a certain tolerance range ) in order to guarantee the quality of the battery ( or capacitor ) .

[0117] According to another aspect of this invention, the machine 1 comprises at least one guiding device 19 ( also called a web guider ) , which is configured to guide / move a portion of at least one strip 3 , 4 of material transversely . The control unit 13 is configured to process the at least one acquired image of the sensor 12 to control the guiding device 19 .

[0118] In particular, the device 19 guides the strip 3 , 4 along a direction T , better illustrated in Figure 3 , transverse to the forward path P of the strip 3 , 4 , upstream of the winding axis A.

[0119] In the non-limiting embodiments illustrated by Figures 1 and 2 , the machine 1 comprises two guiding devices 19 , each arranged at an electrode strip 3 , so as to guide each respective electrode strip 3 along the transverse direction T , prior to winding on the core 6 .

[0120] Generally, the device 19 consi sts of two rollers configured to be moved via an actuating system (not shown) , along the transverse direction T to change the position of the strip 3 along said direction . A well-known actuating system for guiding devices comprises , for example one or more electric motors , for example linear ones . In other words , the guiding devices 19 are used to vary the alignment of the electrode strips 3 with each other and with respect to the separator strips 4 .

[0121] As mentioned, the control unit 13 is configured to determine , as a function of the acquired image , at least one first measurement value relating to an axial position and / or an axial dimension of a first element 20 of the at least one strip on the surface of a portion of winding 2 already formed and at least one second measurement value relating to an axial position and / or dimension of a second element 20 ' of the at least one strip 3 , 4 entering the winding 2 . Therefore , considering that , at the winding core 6 , the direction T is parallel to the direction of the axis A of the core 6 , the axial position of the strip element 20 , and thus in the strip itsel f , can be varied by means of the guiding device 19 .

[0122] The control unit 13 is also configured to control the guiding device 19 to change the position of the at least one strip 3 , 4 of material according to the at least one measurement value . In other words , by processing the signals provided by the sensor 12 , the control unit 13 controls the actuation system to compensate for any misalignment between the electrode strips 3 and / or between the electrode and separator strips 3 , 4 of the winding 2 produced by the machine 1 .

[0123] Advantageously but without imposing limits , the control unit 13 is configured to calculate , for successive portions of strip 3 , 4 , at least one deviation AT between the at least one measurement value and a predefined value .

[0124] Figure 6 schematically illustrates two situations that can be obtained during the production of a winding 2 on the winding core 6 . The winding 2 ' is produced under the assumption of no misalignment of the electrode strips 3 with respect to a nominal position . In this ideal case , the deviation AT between the measurement value and the default value is zero .

[0125] The winding 2 ' ' , on the other hand, has a deviation AT along the transverse direction T , from the nominal position, which, in the example in the figures , is represented by a dotted line . Speci fically, as previously mentioned, this deviation is potentially generated by multiple factors (including machining tolerances) that cannot be easily corrected previously by guiding devices 19 (web guiding systems) or similar.

[0126] In some non-limiting examples, the control unit 13 is configured to implement at least one control algorithm of a type known as feedback control and / or control by means of estimators, e.g. feedforward control.

[0127] In particular, the feedback control is preferably a dual-loop control (e.g. a PID: proportional-integral- derivative) , which comprises a first so-called "fast" loop depending on a sensor (e.g. a photocell) downstream of the guiding devices 19, and a second so-called "slow" loop correcting the value of the lateral position of the strips 3, 4, along the axis A at the winding core 6. For example, preferably but without imposing limits, such control can be implemented by means of a data fusion between a sensor placed upstream of the winding core and the sensor 12.

[0128] Advantageously but without imposing limits, the control unit 13 is configured to implement at least one artificial intelligence algorithm and train it with a sequence of deviations {AH} relative to a sequence of a certain number N of last portions of the at least one strip 3, 4.

[0129] By way of example, N is equal to 100. N is preferably a sufficient number of portions to cover at least one useful period to make the algorithm reliable.

[0130] Advantageously but without imposing limits, the control unit 13 is configured to determine at least one expected deviation ATf for at least one subsequent portion of strip 3, 4, which is subsequent to the sequence of last portions of strip 3, 4, by said at least one control or arti ficial intelligence algorithm .

[0131] Advantageously but without imposing limits , the control unit 13 is configured to control the guiding device 19 when it is traversed by the next portion of strip 3 , 4 in such a way as to control the axial position to compensate for the expected deviation ATf .

[0132] The expected deviation ATf can then be used to control the position of the guiding device 19 along the direction T when the guiding device has the subsequent portion of strip 3 in its grip .

[0133] In accordance with another aspect of this invention, a method is provided for the control of the automatic machine 1 for the production of electrical energy storage devices .

[0134] The method comprises an acquisition step, in which at least one image of the strip 3 , 4 is acquired by means of at least one sensor 12 ; the acquired image comprises at least part of the lateral surface 11 of the winding 2 .

[0135] The method includes a subsequent processing step , in which the acquired image is processed to control the guiding device 19 .

[0136] During the processing step, at least one measurement value relating to an axial position and / or dimension of an element 20 of the strip 3 , 4 is determined depending on the acquired image .

[0137] The method also includes a compensation step, in which the guiding device 19 is controlled to change the position of the at least one strip 3 , 4 of material according to the at least one measurement value .

[0138] Preferably but without imposing limits , the process ing step is calculated for subsequent portions of strip 3 , 4 , at least one deviation {AT} between the at least one measurement value and a predefined value. An artificial intelligence algorithm is trained with a sequence of deviations relating to a sequence of a certain first number N of portions.

[0139] Advantageously but without imposing limits, at least one expected deviation ATf is determined for at least one subsequent portion of strip 3, 4, which is subsequent to the sequence of last portions of strip 3, 4, by means of the artificial intelligence algorithm.

[0140] Advantageously but without imposing limits, during the compensation step, the axial position of a subsequent portion of strip 3, 4 is controlled by means of the guiding device 19 in order to compensate for the at least one expected deviation ATf.

[0141] According to a preferred but non-limiting embodiment, the artificial intelligence algorithm is a recurrent neural network, in particular LSTM or preferably a transformer.

[0142] With reference to Figure 7, the LSTM neural network preferably comprises at least two artificial neurons 31, also known more simply as cells, connected in cascade. The figure illustrates the LSTM neural network at steady state at a given instant of evaluation t. Each cell 31 is trained with a sequence of N previous deviations, i.e. calculated on the basis of the previous N acquisitions (detections) of the sensor 12, this sequence of N deviations being denoted by the notation {ATi}, where i = 1, ...,N, receives as input the previous expected deviation ATf and provides a new predicted deviation ATf. The sequence of N deviations {ATi} represents the long-term memory of the cells 31, while the expected deviation ATf represents the short-term memory of the cells 31. The two cells 31 thus process two different expected deviations ATf (t-l) and ATf (t-2) and two different sequences of N deviations {ATi}(t-l) and {ATi}(t-2) relating to two consecutive detection cycles of the sensor 12.

[0143] The content of each sequence of N deviations {ATi} is saved in a respective shift register 32, only one of which is illustrated in Figure 8. Indeed, it should be noted that the three sequences of N deviations {ATi}(t-2) , {ATi}(t-l) and {ATi}(t) may differ from each other depending on the frequency of updating the respective shift registers 32.

[0144] Preferably, but without imposing limits, training at least one artificial intelligence algorithm includes: updating the training every certain second number NC of new strip portions detected by the sensor 12, adding the relevant new deviations to the sequence of deviations {ATi} and removing the same second number NC of older deviations from the sequence of deviations {ATi} according to a FIFO logic.

[0145] In practice, the training of the artificial intelligence algorithm involves, first of all, updating the shift registers 32 according to the FIFO logic every number NC of sensor 12 detection cycles.

[0146] For example, NC is equal to 1 and thus training is updated by one value every sensor 12 detection cycle, or NC is equal to 3 and thus training is updated by 3 values every 3 detection cycles. Having an NC greater than 1 reduces training repetitions and thus the overall processing of the artificial intelligence algorithm.

[0147] Preferably but not necessarily, since each coil 30, 30' tends to be different, in microscopic terms, from the others, the training of said at least one artificial intelligence algorithm starts from the beginning of the relevant coil 30; 30' . Therefore, each time a new coil 30, 30' of strip 3, 4 is loaded, it is necessary to wait for the acquisition of a sequence of at least N images of N successive portions of strip 3, 4 and the calculation of as many deviations {ATi} before obtaining the first expected deviation ATf and thus having a first compensation. At steady state, the training of the artificial intelligence algorithm is updated cyclically in the manner described above.

[0148] In other, non-limiting embodiments, the algorithm is already partially trained from the data obtained from the previous coils 30, 30', particularly of the same batch.

[0149] By way of example, in Figure 8, ATf (N+l) denotes the expected deviation ATf (t) determined after a sequence of N deviations AT ( 1 ) , ..., AT (N) corresponding to the first N successive portions of strip 3 obtained from the beginning of the electrode strip 3 coil.

[0150] The expected deviation that is used by the control unit to control the position of the guiding device 19 along the direction T is that provided by the last cell 31, with respect to the processing flow of the LSTM network, i.e. that indicated by ATf (t) in Figure 7. In other words, by means of the deviation ATf (t) , the position of the guiding device 19 is changed punctually as the successive portions pass through, for each of which an adjustment is made by the respective prediction ATf (t) . The position of the same portion will only later be detected by the sensor 12 and communicated to the control unit 13, which will compare it to the nominal position and, if necessary, update the related deviation. This makes it possible to detect the position of the portion of strip 3, 4 downstream of the position where the position adjustment is carried out (in the range of mm or tenths of a mm) , allowing for improved space management.

[0151] According to different embodiments, the control unit 13 is configured to use two successive expected deviations ATf (t) and ATf (t-l) for two successive controls, or three successive expected deviations ATf (t) , ATf (t-l) and ATf (t- 2) for three successive controls. This reduces overall processing with only a negligible reduction in forecast accuracy .

[0152] By way of example, in Figure 9, ATf (N+l) , ATf (N+2) and ATf (N+3) denote the expected deviations ATf (t-2) , ATf (t-l) and, respectively, ATf (t) determined after a sequence of N deviations AT ( 1 ) . . . AT (N) corresponding to the first N successive portions of strip 3 obtained from the beginning of the electrode strip 3 coil.

[0153] Although the invention described above makes particular reference to a very specific embodiment, it is not to be considered limited to that embodiment, since it encompasses all those variants, modifications, or simplifications covered by the attached claims, such as, for example: a different arrangement of the coils 30, 30' of the feeding system 7, a different shape of the winding core 6 and, thus, a different shape of the winding, and a different type of sensor 12, and an artificial intelligence algorithm of another kind, etc.

[0154] The present invention has several advantages.

[0155] First of all, this invention makes it possible to improve the quality and thus the performance of the electrical energy storage devices produced. In particular, due to the presence of the control system 8 , this invention makes it possible to carry out the quality control of the windings 2 using one or more optical sensors 12 , 12 ’ .

[0156] In addition, thanks to the system 8 ' , this invention makes it possible to check the quality of the coil 30 , 30 ' of strip 3 , 4 before the winding process . This of fers the advantage of being able to discard non-compliant material before the production process , avoiding machine downtime and the production of low-quality windings .

[0157] In other words , the invention makes it possible to improve the ef ficiency of the automatic machine 1 .

[0158] In addition, the production qual ity of machine 1 is greatly enhanced by the use of one or more arti ficial intelligence algorithms that are trained based on a sequence of deviations between the positions of successive strip portions , detected by the sensor 12 , and a nominal position to determine one or more expected deviations for a subsequent strip 3 , 4 portion . The expected deviations are used to check the transverse position of the guiding device 19 when it is at the subsequent portion of strip 3 , 4 in order to compensate for the expected deviations .

[0159] Finally, by means of the controlled guiding device 19 , this invention makes it possible to reduce the alignment errors of the strips 3 , 4 forming the winding, which consequently leads to improved quality and performance of the electrical energy storage devices produced .

[0160] Thus , the invention enables a very high alignment accuracy of the electrode and separator strips 3 , 4 to be achieved, reducing waste and thus increasing the reliability and productivity of the automatic machine 1 .

Claims

C L A I M S1. A method for quality control of a winding (2) of at least one strip (3, 4) of material for the production of electrical energy storage devices around a winding axis (A) ; the winding (2) comprising a first base surface (9) and a second base surface (10) opposite to each other and transverse to the winding axis (A) and a lateral surface (11) joining the base surfaces (9, 10) with each other; the method comprising: an acquisition step, wherein the at least one image of the at least one strip (3, 4) of material is acquired via the at least one sensor (12) ; a processing step, in which the at least one image is processed to check the quality of the winding (2) ; the method being characterised in that the at least one image comprises at least part of the lateral surface (11) of the winding (2) ; and during the processing step, at least one first measurement value relating to an axial position and / or an axial dimension of a first element (20) of the at least one strip (3, 4) of material on the surface of a portion of the winding (2) already formed is determined as a function of the at least one image, as well as at least one second measurement value relating to an axial position and / or dimension of a second element (20' ) of the at least one strip (3, 4) of material entering the winding (2) ; wherein the quality of the winding (2) is controlled as a function of the at least one first measurement value and the at least one second measurement value.

2. The method according to claim 1, wherein thefirst element (20) and the second element (20' ) each comprise at least one edge (21;22;23) ; and wherein the at least one first measurement value and the at least one second measurement value are determined as a function of the respective least one edge (21;22;23) .

3. The method according to claim 1 or 2, wherein the first element (20) and / or the second element (20' ) are / is the at least one strip (3, 4) of material; in particular wherein the at least one strip (3, 4) of material is an electrode strip (3) .

4. The method according to claim 3, wherein the first element (20) is a first electrode strip (3' ) and the second element (20' ) is a second electrode strip (3' ' ) that is different to the first electrode strip (3' ) .

5. The method according to any one of the preceding claims, wherein the at least one image comprises a longitudinal portion of the lateral surface (11) extending from the first base surface (9) to the second base surface (10) of the winding (2) .

6. The method according to any one of the preceding claims, wherein two distinct images are acquired by means of two distinct sensors (12' , 12' ' ) , wherein the distinct images each comprise a respective end (28) of the winding (2) .

7. The method according to any one of the preceding claims, wherein the acquisition step is performed during the winding of the at least one strip (3, 4) of material, in particular when the winding speed of the at least one strip (3, 4) of material is constant.

8. The method according to any one of the precedingclaims, wherein the acquisition step is performed a plurality of times during the winding of the at least one strip (3, 4) of material around the winding axis (A) ; in particular, wherein the plurality is defined based on a length of the at least one strip (3, 4) of material.

9. The method according to any one of the preceding claims, wherein the acquisition step comprises two substeps : a first acquisition sub-step, wherein a reference image is acquired; and a second acquisition sub-step, wherein the at least one image is acquired; wherein, during the processing step, the at least one measurement value is determined by comparing the at least one image with the reference image; wherein, the at least one measurement value is determined as a deviation between the position of the first element (20) and / or of the second element (20' ) in the reference image and the position of the first element (20) and / or of the second element (20' ) in the at least one acquired image; more specifically, during the processing step, it is verified that the deviation is within a predefined acceptability range; in particular, the acceptability range is from -1 mm to 1 mm, more particularly from -0.3 mm to 0.3 mm, more preferably from -0.1 mm to 0.1 mm.

10. The method according to any one of the preceding claims wherein the processing step comprises two substeps : a determination sub-step, wherein the actualdistance between the first base surface (9) and the second base surface (10) is determined; and a comparison sub-step, in which the actual distance is compared with a predefined ideal width of the winding (2) .

11. A system for quality control of a winding (2) of at least one strip (3, 4) of material for the production of electrical energy storage devices around a winding axis (A) ; the winding comprising a first base surface (9) and a second base surface (10) opposite to each other and transverse to the axis (A) of winding, and a lateral surface (11) joining the base surfaces (9,10) with each other; the system (8) comprising: at least one sensor (12) configured to acquire at least one image of the at least one strip (3, 4) of material; and a control unit (13) configured to process the at least one image to control the quality of the winding (2) ; the system (8) being characterised in that the at least one sensor (12) is arranged such that the at least one image comprises at least part of the lateral surface (11) of the winding (2) ; and the control unit (13) is configured to determine, as a function of the at least one image, at least one first measurement value relating to an axial position and / or an axial dimension of a first element (20) of the at least one strip (3, 4) of material on the surface of a portion of the winding (2) already formed and at least one second measurement value relating to an axial position and / or dimension of a second element ( 20 ’ ) of the at least onestrip (3,4) of material entering the winding (2) ; wherein the control unit (13) is configured to control the quality of the winding (2) as a function of the at least one first measurement value and the at least one second measurement value .

12. The system according to claim 11 comprising two distinct sensors (12' , 12' ' ) configured to acquire two distinct images comprising, each, at least one respective end (28) of the winding (2) .

13. The system according to claim 11 or 12, wherein the at least one sensor ( 12 ; 12 ’ ; 12 ’ ’ ) is a camera and / or video camera comprising a telecentric lens.

14. An automatic machine for the production of electrical energy storage devices, the machine (1) comprising at least one winding core (6) of elongated shape configured to receive and wind at least one electrode strip (3) and / or one separator strip (4) so as to form a winding (2) ; the machine (1) being characterised by comprising a system (8) for quality control of the at least one winding (2) according to any one of claims 11 to 13.

15. The machine according to claim 14 and comprising at least one coil ( 30 ; 30 ’ ) of the at least one strip (3, 4) of material and at least one further control system (8' ) arranged upstream of the at least one winding core (6) at the coil ( 30 ; 30 ' ) of the at least one strip (3, 4) of material; the control system (8' ) being configured to acquire at least one image of the at least one strip (3, 4) of material to determine a width measurement of the at least one strip (3, 4) of material.

16. The machine according to claim 15, wherein the control unit (8' ) is configured to receive the width measurement of the at least one strip (3, 4) of material and to use it as a reference to determine the at least one measurement value.

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