Abstract:
There is described a laminating apparatus for coupling electrodes of non-rectangular shape with a separating film for the manufacture of electric energy accumulating devices, wherein a pair of laminating rollers has a roller driven by an elastic arrangement loaded with a variable force adjusted by an endless screw conveyor controlled by a brushless motor, during the passage of the electrodes, so as to vary the laminating force according to the width of the electrode laminated instant by instant, in order for the laminating pressure to remain almost constant

Description:
BACKGROUND OF THE INVENTION 
       [0001]    This invention relates to a laminating apparatus, in particular to an apparatus for coupling electrodes with a separating film by way of lamination. 
         [0002]    Specifically, but not exclusively, this apparatus may be used to manufacture electric energy accumulating devices. 
         [0003]    In particular, reference is made to a roll laminating apparatus that may be advantageously used to laminate flat objects of non-rectangular shape. 
         [0004]    A problem with the roll lamination of objects of non-rectangular shape is to ensure a laminating pressure that is constant all over the surface of the object to be laminated. Indeed, when an object of non-rectangular shape passes between two laminating rollers, the width of the object subjected—instant by instant—to the laminating force applied by the rollers varies depending on the shape of the object. 
         [0005]    If the laminating pressure (always equal to the ratio between the laminating force applied by the rollers and the surface subjected to such force) is not constant, there is the risk to make a product that has been subjected—in some areas—to an insufficient laminating pressure, such that it may be incorrectly assembled, and/or has been subjected—in other areas—to an excessive laminating pressure, with consequent possible damage to the product, in particular to the separating film, whereby the latter may lose—at least in part—the features that are necessary to manufacture a good-quality electric energy accumulating device. 
       SUMMARY OF THE INVENTION 
       [0006]    An object of the invention is to provide a laminating apparatus capable of solving the aforesaid prior art problem. 
         [0007]    An advantage is to provide a laminating apparatus of the type comprising rollers, capable of laminating flat-shaped objects with a laminating pressure which is practically constant all over the surface of the objects. 
         [0008]    An advantage is to achieve high-quality lamination for flat objects of non-rectangular shape. 
         [0009]    An advantage is to provide a laminating apparatus suitable for laminating flat, non-rectangular electrodes with a continuous separating film, in particular for the manufacture of electric energy accumulating devices. 
         [0010]    An advantage is to achieve an assembly with a stable, strong coupling between electrodes and separating film, without damaging the separating film. 
         [0011]    An advantage is to provide an apparatus that is structurally simple and inexpensive, featuring high productivity and excellent reliability. 
         [0012]    These and other objects and advantages are achieved by the apparatus according to one or more of the claims reported below. 
         [0013]    In an example, a laminating apparatus has a pair of laminating rollers, wherein one of the two rollers is thrust by elastic means loaded with a variable force so as to vary the laminating force applied by the rollers in a laminating zone comprised between the rollers, and wherein a programmable electronic processor controls a motor that adjusts the load of the elastic means, such that when an object to be laminated passes between the rollers, the laminating force is varied depending on the width of the object that instant by instant passes through the laminating zone, in order for the laminating pressure to remain almost constant. The motor may drive the movement of a movable element (e.g., the translating element of an endless screw conveyor) interacting with the elastic means with a load depending on the position of the element itself. The electronic processor may be equipped with both a data input unit for receiving information on the object to be laminated and a processing unit for associating the object to be laminated with a preset law of motion of the movable element so as to vary the laminating force to be applied during the passage of the object. This preset law of motion may be selected among a plurality of laws of motion stored in an electronic memory connected to the processor. The apparatus may be equipped with sensor means arranged upstream of the laminating zone, along an supplying path of the object, for detecting the passage of the objects to be laminated, such that the movement of the movable element, and the related variation of the laminating force, be in phase with the passage of the objects through the laminating zone. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    The invention may be better understood and implemented with reference to the attached drawings, these showing non-limiting exemplary embodiments. 
           [0015]      FIG. 1  shows a vertical elevation diagram of a first example of a laminating apparatus according to the present invention. 
           [0016]      FIG. 2  shows a schematic plan view from above of a product that may be laminated with an apparatus provided according to the invention. 
           [0017]      FIG. 3  shows a vertical elevation front view of a second example of a laminating apparatus according to the present invention. 
           [0018]      FIG. 4  shows section IV-IV of  FIG. 3 . 
           [0019]      FIG. 5  shows a right-side view of  FIG. 3 . 
           [0020]      FIG. 6  shows section VI-VI of  FIG. 5 . 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    Referring to the aforesaid  FIGS. 1-6 , by the numeral  1  there is indicated as a whole a laminating apparatus that may be used in particular for manufacturing electric energy accumulating devices (batteries, capacitors, etc.). In particular, the laminating apparatus  1  may be used to couple at least one flat electrode E of non-rectangular shape with at least one separating film S. For the sake of clearer illustration, in the figures the same reference numerals are used to designate like elements of the several exemplary embodiments. 
         [0022]    The apparatus  1  comprises a first (upper) laminating roller  2  and a second (lower) laminating roller  3  that are coupled together and opposite each other to define a laminating zone extending between the rollers. In particular, the two laminating rollers  2  and  3  have rotational axes that are parallel to each other (horizontal). The laminating zone may extend in width in a direction parallel to the axes of the two laminating rollers  2  and  3 . 
         [0023]    Through the laminating zone extending between the rollers  2  and  3  there passes an object to be laminated (e.g., one or more electrodes E arranged one after the other, in a row, to be assembled with at least one continuous separating film S), this being supplied in an advancement direction F that is transverse to the width of the laminating zone. In particular, the advancement direction F may be perpendicular to the plane containing the axes (parallel to one another) of the laminating rollers  2  and  3 . 
         [0024]    The first (upper) roller  2  may be rotatably mounted on a support  4  connected by (first) elastic means  51  (or regulating elastic means  51 ) to a movable element  6 , the movement of which causes variation in the load of the first elastic means  51  and the consequent variation in the laminating force exerted by the rollers  2  and  3  on the object in the laminating zone. 
         [0025]    The load of the first laminating roller  2  may rest, at least in part, on additional or second elastic means  52  (or roller supporting elastic means  52 ). The second elastic means  52  may be designed to balance and/or support at least one part, comprised between 50% and 100%, of the weight of the first roller  2 . 
         [0026]    The apparatus  1  may comprise a motor  7  that drives the (vertical) movement of the movable element  6 . The motor  7  may comprise a brushless motor, for example. 
         [0027]    As in the examples illustrated herein, the movable element  6  may comprise a translating part of a mechanism for transforming a rotary motion of a rotary shaft  8  of the motor  7  into a translation movement of the aforesaid translating part of the mechanism. For example, this mechanism may comprise a screw-nut screw mechanism, in particular a ball bearing screw  9 . 
         [0028]    The apparatus  1  may comprise programmable electronic motor control means. These control means may comprise, for example, a control unit (CPU), not shown, and computer program instructions executable by the control means. In particular, the control means may comprise means for moving the movable element  6  whilst the product to be laminated traverses the laminating zone, making the movable element  6  follow a preset law of motion so as to vary the laminating force according to the width of the product that instant by instant is in the laminating zone, in order for the laminating pressure to remain almost constant.  FIG. 2  shows an example of an object to be laminated. This object comprises the continuous separating film S upon which a plurality of electrodes E is arranged one after the other, in a row. The object is supplied for lamination according to the advancement direction F. These electrodes E may have a non-rectangular shape, such that the width of the electrodes E (i.e., their dimension in a direction transverse to the advancement direction and/or in a direction parallel to the width of the laminating zone) is not constant: a single electrode E may have a laminating zone having a width L 1  and another laminating zone having a width L 2 ≠L 1 . In this specific case (L 2 &gt;L 1 ), in order to achieve an almost constant laminating pressure, the laminating force F 1  applied on a portion of object with a width less than L 1  shall be less than the laminating force F 2  applied on a portion with a width greater than L 2 , e.g., proportionally such that F 1 /L 1 =F 2 /L 2 . 
         [0029]    The control means may comprise means for receiving information on the object to be laminated, for example information relating to the shape and/or size and/or type of object, and means for setting a desired law of motion of the element  6  on the basis of the information received. In particular, these control means may comprise means for storing two or more laws of motion for the movable element  6  and means for associating one of the aforementioned stored laws of motion with the aforesaid information relating to the object to be laminated. 
         [0030]    The apparatus  1  may comprise sensor means  10  for measuring the laminating force applied by the first laminating roller  2 , and means for characterising the first elastic means  51  by determining the course of the laminating force according to the position of the movable element  6 . The control means may comprise means for receiving a desired law of variation of the laminating force (for example a law of variation calculated on the basis of the shape of the objects to be laminated, in order to obtain a desired laminating pressure that is almost constant all over the surface of the objects), and processing means that uses the characterisation of the first elastic means  51 , and determines—by so doing—a desired law of motion of the movable element  6  which causes the desired law of variation of the laminating force. 
         [0031]    For example, the force sensor means may comprise at least a load cell or another force transducer. 
         [0032]    The apparatus  1  may comprise first supplying means for supplying flat objects (of non-rectangular shape), for example electrodes E, one by one to the laminating zone, and second supplying means for supplying a continuous film S, for example a separating film, to the laminating zone in cooperation with the first supplying means, such that the flat objects are coupled with the continuous film in the laminating zone. The first supplying means may be arranged so as to deposit the flat objects one after the other, in a row, on the continuous film. In  FIGS. 3-6 , the first and second supplying means (which may comprise supplying means of a known type and thus not described in greater detail) are shown at least in part. In particular, by the numeral  11  there is indicated a (horizontal) transporting plane upon which there advances the product to be laminated. One may expect that the product to be laminated (separating film S and electrodes E) be preheated, for example in a known manner, prior to reaching the laminating zone. 
         [0033]    The apparatus  1  may comprise sensor means (of a known type, for example) arranged upstream of the laminating zone, along a supplying path P of the object to be laminated, to detect the position of the object. These position or proximity sensor means may comprise contactless sensor means (e.g., of the optic, ultrasonic, magnetic type, and so on) or of another type. 
         [0034]    The control means may comprise means for bringing the motor  7  that drives the movable element  6  into phase with the detected position of the object moving forward, such that the variation in the laminating force (which depends on the variation in the position of the movable element  6 ) be in phase with the passage of the object through the laminating zone, in order to obtain the desired laminating pressure. 
         [0035]    In use, a laminating roller driving motor  12 , for example a motor  12  applied to the second (lower) roller  3  and/or the first (upper) roller  2 , provides for the rotation of the rollers whilst the product to be laminated (electrodes E on the film S) moves forward towards the laminating zone. In this particular case, both rollers  2 ,  3  are motor-driven. The control means sets the desired law of motion of the movable element  6 . For example, the law of motion may be either calculated on the basis of the state of the width L of the product (in particular the electrodes E) or selected from a group of laws by associating the type of product to the corresponding law. 
         [0036]    The variation in the position of the movable element  6  will cause a variation in the load on the first elastic means  51  and the consequent variation in the laminating force. The adjustment of the position of the movable element  6  begins when at least one end of the product (the front or forward end of the electrode E) enters the laminating zone. This phasing of the adjustment may be provided on the basis of the position signal emitted by the sensor means detecting the position of the product, arranged upstream of the laminating zone. 
         [0037]    The laminating zone comprises a line or a thin strip extended in width, parallel to the roller axis. At least one part of the product to be laminated (electrode E) has a varying width L (as it is non-rectangular in shape). When the product passes, the laminating force F L  is varied, such that the laminating pressure (almost proportional to the ratio F L /L) is kept constant. 
         [0038]    The lamination results to be regular and uniform all over the surface of the laminated product. It is thus possible to obtain a constant laminating pressure suitable for reaching the desired, sufficiently strong and resistant coupling, in particular between the separating film S and the electrodes E, without causing any excessive stress on some parts of the laminated product, in particular on the (polymeric) material of the separator, since an excessive stress on the latter may result in either a loss of or a decrease in its features, e.g., the electric properties, useful to manufacture an efficient electric energy accumulating device.