Patent Publication Number: US-2022228903-A1

Title: Weighing system for a capsule filling machine

Description:
The present invention relates to apparatuses and systems for weighing items, in particular capsules, shells, tablets or similar elements in process machines. In particular, the invention relates to a weighing system that can be associated with a capsule filling machine to measure the weight of the capsules, and more precisely of the product or products dosed in the capsules. 
     In the filling processes of capsules with liquids, powders, granules, cronoids, tablets, etc., the use of weighing systems positioned downstream of a filling station of the filling machine in order to measure the weight of the product dosed in the capsules is known. The capsules, which are typically made of hard gelatin, HPMC, polymers, etc. are, as known, formed by a body and a cap which can be temporarily decoupled and separated to allow one or more products to be dosed into the body. 
     Weight control is necessary to reject non-compliant capsules from the production because they contain a quantity of product outside the allowed dosage tolerance range and to correct possible excesses or defects in the product dosage, by acting in feedback on the filling station. In fact, especially in the pharmaceutical field it is very important to verify that the quantity of product dosed in the individual capsules is exactly the required one, with very narrow tolerance ranges. 
     Generally capsules are only weighed once at the end of the dosing, since the weight of the empty capsules is known and included within a defined tolerance range, indicated and guaranteed by the suppliers/producers of the capsules. In this way, by subtracting the known weight of the empty capsule (tare) from the measurement of the weight of the filled capsule (gross weight) it is possible to calculate the weight of the dosed product (net weight) with a certain degree of precision. 
     However, in filling processes in which the quantity of product to be dosed in the capsules is very small, for example a few milligrams (so-called “micro-doses”), and the tolerance range required for the dosage of the product is limited, for example ±10%, the normal weight variations of the empty capsules strongly influence and affect the weight measurement. Indeed, since the weight of the empty capsules is comparable to that of the dosed product, these empty capsule weight variations can be larger than the tolerance range of the allowed dosage. In this case, checking only the weight of the filled capsule is insufficient for guaranteeing that the quantity of dosed product is within the required limits and it is necessary to weigh the empty capsule beforehand and calculate the difference in weight of the dosed product. 
     Solutions are therefore known which provide a first weighing station, upstream of the filling machine or of the filling station, which measures the weight of the capsules or of the empty bodies (tare), and a second weighing station, downstream of the filling station, which measures the weight of the capsules or bodies filled with the product (gross weight). The difference of the two measured weights allows precisely calculating the net weight of the dosed product. 
     The weighing apparatuses that perform this type of direct measurement include electronic scales typically equipped with a plurality of weighing cells, or load cells, each of which is equipped with a respective support (plate) on which the capsule or body can be positioned for the time necessary for the correct measurement. 
     The weight check can be of the total type, i.e. performed on all the filled capsules in the filling station (so-called 100% weight control) or a partial, statistical type check carried out on a sample of filled capsules. 
     In certain types of pharmaceutical production, however, the control of all the filled capsules is required and in general this solution is widely preferred by pharmaceutical companies in order to guarantee a better quality of the packaged product. 
     Suitable transfer means are provided for taking the capsules from a transport device of the filling machine and positioning them on the supports of the load cells and then for returning the capsules to the transport device after their weighing. The weighing procedure—which comprises the transfer of the capsule from the transport device to the load cell, its weighing on the latter and its transfer from the load cell to the transport device—is carried out in one of the pause intervals of the intermittent motion with which the filling machine moves. 
     It is known that to perform an accurate and precise weighing using scales with electronic load cells, an adequate measurement time is necessary. In particular, between the deposition of the capsule on the load cell support and the measurement of its weight, a minimum interval of time must elapse, necessary to allow the load cell to stabilize or to allow the damping of the vibrations that are generated by resting the capsule on the support and to proceed with the weight detection. 
     To ensure an adequate amount of time for measuring the weight of the capsules, the movements for transferring the capsules are performed by the transfer means as quickly as possible. 
     It has been found, however, that such movements, in particular the deposition and/or insertion of the capsules on the supports, can generate anomalous mechanical stresses on the supports themselves and therefore on the relative load cells, which can lead to malfunctions and even breakages of one or more of the load cells, this requiring the replacement of the scales as well as the stopping of the filling machine and therefore of production. In particular, the insertion movement of the capsule on the support can cause an excessive stroke of the load cell support and/or axial thrusts which can alter the calibration of the load cell or even damage the load cell. 
     An object of the present invention is to improve the known weighing systems provided with electronic scales with load cells and associable with capsule filling machines for measuring the weight of the capsules and, in particular of the product(s) dosed in the capsules. 
     Another object is to provide a weighing system that allows operating at high speeds while preserving the integrity and functionality of the load cells of the scales, i.e. avoiding excessive mechanical stresses on the load cells. 
     A further object is to provide a weighing system which allows measuring the weight of all the filled capsules, even at high operating speeds of the filling machine. 
     Still another object is to provide a weighing system which is particularly compact and of limited dimensions and has reliable and safe operation. 
     These objects and others are achieved by a weighing system according to one of the claims set forth below. 
    
    
     
       The invention can be better understood and implemented with reference to the attached drawings which illustrate some exemplifying and non-limiting embodiments thereof, wherein: 
         FIG. 1  is a partially sectioned schematic view of a weighing system according to the invention associated with a capsule filling machine, partially shown, in a first operating step of a weighing process; 
         FIG. 2  is an enlarged partial view of the weighing system of  FIG. 1 ; 
         FIG. 3  is a partially sectioned schematic view of the weighing system of the invention in a second operating step; 
         FIG. 4  is an enlarged partial view of the weighing system of  FIG. 3 ; 
         FIG. 5  is a partially sectioned schematic view of the weighing system of the invention in a third operating step; 
         FIG. 6  is a partially sectioned schematic view of the weighing system of the invention in a fourth operating step; 
         FIG. 7  is an enlarged, partial and partially sectioned view of a variant of the weighing system of the invention in a non-operating step; 
         FIG. 8  is a view similar to that of  FIG. 7  which shows the weighing system in a weighing operating step; 
         FIG. 9  is an enlarged perspective view of a capsule gripping element of the weighing system of  FIG. 7 ; 
         FIG. 10  is a schematic plan view of a capsule filling machine comprising a pair of weighing systems according to the invention. 
     
    
    
     With reference to  FIGS. 1 to 6 , the weighing system  1  of the invention is illustrated, which can be associated with a filling machine  200  arranged to fill capsules  100  or similar elements with at least one product in liquid, powder, granule, cronoid, tablet form, etc., in particular a pharmaceutical product. Each capsule  100  is made of hard gelatin and is formed by a body  100   a  and a cap  100   b  which can be temporarily decoupled and separated to allow one or more products to be dosed in the body  100   a.    
     The weighing system  1  comprising a weighing unit  2  which includes at least one scale provided with at least one weighing cell or load cell  3 , in particular of electronic type, and with a respective gripping element  7  connected to the weighing cell  3  through a loading stem  4  and equipped at one end with a housing  17  arranged to receive and retain a capsule  100  or a body  100   a  to be weighed. In particular, in the embodiment described and illustrated in the figures by way of non-limiting example, the weighing unit  2  is arranged to weigh the bodies  100   a  of the capsules  100 , but the structure and the operation of the weighing system  1  of the invention described below are the same also in the case of weighing whole capsules  100 . 
     The weighing system  1  also comprises a connecting element  5  rigidly fixed to the corresponding loading stem  4  of the weighing cell  3  and slidably and elastically supporting, through the interposition of elastic means  6 , the gripping element  7 . The gripping element  7  can be moved linearly, in particular along a direction of movement L, between a measuring position A and an end-stroke position B. In the measuring position A the gripping element  7  is completely supported by the loading stem  4  and thus by the weighing cell  3 , spaced by means of the elastic means  6  from an abutment wall  10  of the weighing unit  2 , so as not to abut the latter, in particular to allow weighing a body  100   a  (or a capsule  100 ) supported by the same gripping element  7 . In the end-stroke position B that is reached by a movement of the gripping element  7  with respect to the connecting element  5  which counteracts a thrust of the elastic means  6 , the gripping element  7  abuts the abutment wall  10 . 
     It should be noted that the elastic means  6  are configured, in particular sized, so that a displacement d of the gripping element  7  between the measuring position A and the end-stroke position B (stroke of the gripping element  7 )—thanks to the aforesaid elastic means  6  which are compressed—is carried out so as not to cause any displacement of the loading stem  4  of the weighing cell  3  so as to preserve the integrity and functionality of the weighing cell  3 , as better explained in the following description. 
     For this purpose, the gripping element  7  comprises an abutment end  18  opposite the housing  17  and arranged facing the abutment wall  10  of the weighing unit  2  so as to abut the latter. 
     The gripping element  7  also comprises a connecting cavity  16  opposite the housing  17  and arranged to receive a coupling portion  15  of the connecting element  5 , with the elastic means  6  which are interposed between the aforementioned coupling portion  15  and a bottom wall  16   a  of the connecting cavity  16 . 
     In the embodiment illustrated in  FIGS. 1 to 6 , the gripping element  7  has a substantially cylindrical shape and comprises an upper part  7   a  in which the connecting cavity  16  is realized and which includes the abutment end  18 , and a lower part  7   b  in which the housing  17  is realized. 
     With particular reference to  FIG. 2 , the connecting cavity  16  has a substantially cylindrical shape so as to receive with small clearance the coupling portion  15  of the connecting element  5 , also substantially cylindrical and provided with an annular lightening groove. The gripping element  7  is connected to the connecting element  5  by means of a fixing element  14 , for example a screw, which also supports and guides the elastic means  6 , the latter comprising for example a helical spring acting in compression. In particular, the fixing element  14  passes through the elastic means  6  or, in other words, the helical spring  6  is mounted on the screw  14  and interposed between the bottom wall  16   a  of the connecting cavity  16  and a compartment  27  provided in the coupling portion  15 . 
     The screw  14  is fixed to the coupling portion  15  of the connecting element  5  and is slidably connected to the gripping element  7 . More precisely, a threaded stem  14   a  of the screw  14  is screwed to the coupling portion  15 , while its head  14   b  is housed in a first seat  13  of the gripping element  7 . 
     In the measuring position A, the helical spring  6  acting on the bottom wall  16   a  of the connecting cavity  16  keeps the abutment end  18  detached and spaced from the abutment wall  10  by a distance corresponding to the displacement (stroke) d that the gripping element  7  can carry out between the measuring position A and the end-stroke position B. This distance can be adjusted by suitably acting on the screw  14  screwed to the connecting element  5 . 
     In the end-stroke position B, the helical spring  6  is compressed and the gripping element  7 , counteracting the thrust of the helical spring  6 , abuts the abutment wall  10 . Since the displacement d of the gripping element  7  between the weighing position A and the end-stroke position B does not cause, due to the presence of the helical spring  6  which is compressed, a displacement of the loading stem  4  of the weighing cell  3 , the latter does not remain damaged or altered by the insertion of the body  100   a  in the gripping element  7  regardless of an (also high) insertion speed. 
     The coupling portion  15  also comprises at least one centring protrusion  25  arranged to couple with second seat  26  having a substantially complementary shape and carried out on the bottom wall  16   a  of the connecting cavity  16 ; the shape coupling between the centring protrusion  25  and the second seat  26  substantially prevents, in operation, a relative rotation of the gripping element  7  with respect to the connecting element  5  about a longitudinal axis substantially coinciding with a longitudinal axis X of the loading stem  4 . The latter comprises a connection end  4   a  inserted and locked with a transverse fixing dowel  28  in a further connecting cavity  24  realized at one end of the connecting element  5  opposite the coupling portion  15 . 
     In the embodiment illustrated in  FIGS. 1 to 6 , the weighing system  1  of the invention further comprises transfer means  20  arranged to transfer the capsules  100  or the bodies  100   a  from a moving device  201  of the filling machine  200  to a gripping element  7  and vice versa, i.e. from a gripping element  7  towards a moving device  201  of the filling machine  200 . The housing  17  of the gripping element  7  is configured to receive and retain the respective body  100   a  to be weighed through force or interference coupling. 
     As better explained in the description that follows, the transfer means  20  by transferring or pushing the capsule  100  or the body  100   a  into the gripping element  7  moves the latter to the end-stroke position B. In other words, the transfer means  20  pushes the gripping element  7  to the end-stroke position B by means of or through the capsule  100  or the body  100   a.    
     The moving device  201  comprises, for example, a plurality of supports  223  with respective seats  233 ,  234  for housing and moving the bodies  100   a  and caps  100   b  of the capsules  100  in sequence through the various operating stations of the filling machine. For example, the moving device  201 , of a known type, comprises a carousel or table, rotatable about a vertical rotation axis and provided with a plurality of supports  223 , arranged angularly spaced along the periphery or a circumferential edge of the aforementioned carousel. Each support  223  is formed by a first support element  231 , having a plurality of first seats  233 , intended to house the bodies  100   a  of the capsules  100  and a second support element  232 , having a plurality of second seats  234  intended to house the caps  100   b  of the capsules  100 . The support elements  231 ,  232  have an elongated shape and are movable with respect to one another between an overlapping position in which the respective seats  233 ,  234  are aligned and overlapped for insertion or removal of the entire capsules  100  (i.e. with the caps  100   b  applied to the respective bodies  100   a ) and an offset position in which the first seats  233  containing the bodies  100   a  are accessible to allow the dosing of the product. 
     The transfer means  20  is movable along an insertion/extraction direction E, in particular substantially vertical, and comprises a first transfer element  21  and a second transfer element  22 . The first transfer element  21  is arranged to insert the body  100   a  in the housing  17  so as to allow the weighing cell  3  to measure the weight of the body; the second transfer element  22  is arranged to remove the body  100   a  from the housing  17  after measuring the weight of the body. 
     More precisely, the first transfer element  21  is arranged to remove a body  100   a  from a respective first seat  233  of the moving device  201  and then insert it in the housing  17  of the gripping element  7 , while the second transfer element  22  is arranged to remove the body  100   a  from the housing  17  and insert this body  100   a  in the respective first seat  233  of the moving device  201 , once the weight has been measured. 
     The first transfer element  21  and the second transfer element  22  are movable along the insertion/extraction direction E, in particular substantially vertical, between a first operating position P 1 , a second operating position P 2 , a third operating position P 3  and a fourth operating position P 4 . 
     In the first operating position P 1  the transfer elements  21 ,  22  are more spaced from the loading stem  4 , in particular in a distal position, in particular disengaged and spaced from the body  100   a , housed in the respective first seat  233  of the moving device  201 , so as not to interfere with the movement of the latter. In the second operating position P 2 , the transfer elements  21 ,  22  are closer to the loading stem  4 , in particular in a proximal position, so as to insert the body  100   a  inside the housing  17  of the gripping element  17 , in particular after the first transfer element  21  has completely extracted the body  100   a  from the respective first seat  233  of the moving device  201 . In the third operating position P 3  the transfer elements  21 ,  22  are spaced from the loading stem  4  in an intermediate position between the first operating position P 1  and the second operating position P 2  not in contact with the body  100   a  that is housed and retained by force or interference coupling in the housing  17 , so as to allow the weighing cell  3  to measure the weight of the body  100   a . In the fourth operating position P 4  the second transfer element  22  has completely extracted the body  100   a  from the housing  17  of the gripping element  7  and inserted it inside the respective first seat  233  of the moving device  201 . 
     It should be noted that, in the second operating position P 2  of the transfer elements  21 ,  22 , the gripping element  7  is pushed—by means of the action of the body  100   a  in turn pushed by the first transfer element  21  inside the housing  17  and blocked therein by interference—in the end-stroke position B in which it abuts the abutment wall  10 . In this way, the mechanical stresses (axial thrusts) transmitted to the gripping element  7  by the first transfer element  21 , movable along the insertion/extraction direction E, are not transferred and unloaded on the weighing cell  3 , but on the abutment wall  10  of an external casing of the weighing unit  2 . 
     In the third operating position P 3  of the transfer elements  21 ,  22  which are disengaged and spaced from the body  100   a  and therefore also disengaged from the gripping element  7 , the latter—no longer pushed by the first transfer element  21  through the body  100   a —can be returned to the weighing position A by the helical spring  6  so as to be spaced from the abutment wall  10  and be completely supported by the loading stem  4  of the weighing cell  3  which can accurately and precisely weigh, without interference, the body  100   a  inserted in the housing  17 . 
     In the embodiment of the weighing system  1  of the invention illustrated in  FIGS. 1 to 6 , the weighing unit  2  with the gripping element  7  is arranged above the moving device  201 , in particular with the gripping element  7  extending vertically downwards and towards the moving device  201 . The housing  17  of the gripping element  7  has an inlet end  17   a  which allows the transfer means  20  to insert/extract the body  100   a  in/from said housing  17  along the insertion/extraction direction E. The inlet end  17   a  of the housing  17  has a bevelled or rounded edge to facilitate the insertion of the body  100   a.    
     The first transfer element  21  has an elongated shape and is arranged to enter, when moved along the insertion/extraction direction E, inside a respective first seat  233  of the moving device  201  to abut, in the illustrated embodiment, a lower portion of a body  100   a  and push the latter out of the first seat  233  and inside the housing  17 . The first transfer element  21  is inserted into the first seat  233  through an inlet end thereof so as to abut and push the body  100   a  to exit the first seat  233  through an opposite upper opening thereof. The second transfer element  22  also has an elongated shape and has at least one end portion  22   a  adapted to abut an upper portion of the body  100   a  to push the latter out of the housing  17  and inside the first seat  233 . More specifically, the second transfer element  22  substantially has an inverted “L” shape and comprises a first elongated portion, parallel to the insertion/extraction direction E and a second portion orthogonal to the insertion/extraction direction E which forms the end portion  22   a.    
     The first transfer element  21  and the second transfer element  22  are fixed to a base element  23  of the transfer means  20  which is moved by actuation means, of known type and not shown in the figures, along the insertion/extraction direction E, between the different operating positions P 1 , P 2 , P 3 , P 4 . 
     The gripping element  7  has one or more lateral openings  19 , in particular parallel to the insertion/extraction direction E, which allow the insertion and sliding of the second transfer element  22 , in particular the end portion  22   a  thereof, inside the housing  17  and along the insertion/extraction direction E. 
     The housing  17  extends longitudinally, in particular parallel to the insertion/extraction direction E, and has an extension such as to contain the body  100   a  or the capsule  100 . The housing  17  is also convergent or tapered starting from the inlet end  17   a  towards the weighing cell  3  since the transverse section of the housing  17  (almost orthogonal to a longitudinal axis of the gripping element  7  which is parallel to the insertion/extraction direction E) progressively decreases starting from the inlet end  17   a  down to a size smaller than a transverse dimension of the body  100   a  or the capsule  100 . In this way, the housing  17  is able to receive and, upon completed insertion, retain the body  100   a  by force or interference coupling. More precisely, the body  100   a  can be inserted and progressively forced into the housing  17  in which it remains reversibly locked by virtue of the elasticity of the material (gelatin) with which it is made and its hollow shape. 
     In the illustrated example, the capsule  100 , the body  100   a  and the cap  100   b  have a hollow cylindrical shape (the body  100   a  and the cap  100   b  are also provided with respective spherical bottoms) and the housing  17  has a truncated conical shape, converging in the direction of the weighing cell  3  and with a transverse section, in particular internal, which is circular. 
     The weighing system  1  of the invention can include a weighing unit  2  having a plurality of gripping elements  7 , in a number equal to the number of the seats  233 ,  234  of each support  223  of the moving device  201 , and an equal number of weighing cells  3 . In this way, all the bodies  100   a  housed in the first seats  233  of a first support element  231  of a support  223  can be weighed at the same time by the weighing unit  2 . Likewise, the transfer means  20  comprise a plurality of first transfer elements  21  and a respective plurality of second transfer elements  22 , in a number equal to the number of the seats  233 ,  234  of each support  223  of the moving device  201 , so as to simultaneously transfer all the bodies  100   a  housed in the first seats  233  in the housings  17  of the gripping elements  7  and vice versa. 
     With particular reference to  FIGS. 1 to 6 , during the operation of the weighing system  1  of the invention associated with the filling machine  200 , in particular with a weighing station thereof, in one of the pause steps of the intermittent motion with which the moving device  201  of the filling machine  200  moves, the transfer means  20  transfers the empty bodies  100   a , contained in the seats  233  of the first support element  231  of a support  223 , into the respective gripping elements  7  of the weighing unit  2 . More precisely, the first transfer elements  21  of the transfer means  20  are moved, together with the second transfer elements  22 , from the first operating position P 1  ( FIG. 1 ) to the second operating position P 2  ( FIG. 3 ) so as to remove the bodies  100   a  from the respective first seats  233  and insert them, by force, into the respective housings  17  of the gripping elements  7 . 
     In the upwards movement along the insertion/extraction direction E, in the second operating position P 2 , each gripping element  7 , which is slidably and elastically connected to the loading stem  4  of the respective weighing cell  3  by means of the interposed corresponding connecting element  5 , is arranged in the end-stroke position B in which its abutment end  18  abuts the abutment wall  10  of the weighing unit  2 . In this way, the mechanical stresses (axial thrusts) transmitted on the gripping element  7  by the first transfer element  21 , which by force inserts and locks the body  100   a  into the housing  17 , are not transferred and unloaded on the weighing cell  3 , but on the abutment wall  10 . It should be noted that the displacement d of the gripping element  7  between the measuring position A and the end-stroke position B thanks to the elastic means  6  (suitably sized), which are compressed, does not cause any movement of the loading stem  4  of the weighing cell  3 . Therefore, the transfer of the body  100   a  from the respective seat  233  to the gripping element  7  performed by the transfer means  20  does not damage or harm the regular operation of the weighing cell  3 , even with high movement speeds of the first transfer element  21 . 
     The transfer elements  21 ,  22  are then moved to the third operating position P 3  ( FIG. 5 ) in which they are disengaged and spaced from the body  100   a  housed and retained by force in the housing  17  to allow the weighing cell  3  to measure the weight thereof. 
     In the third operating position P 3  the transfer elements  21 ,  22  are disengaged also from the gripping element  7  which in this way, no longer subject to any thrust by the first transfer element  21  through the body  100   a , is returned to the measuring position A by means of the helical spring  6 . In the measuring position A the gripping element  7  is spaced from the abutment wall  10  and completely supported by the loading stem  4  of the weighing cell  3  to allow the body  100   a  inserted in the housing  17  to be weighed accurately and precisely, without interference or disturbance. 
     Once the weight of the empty bodies  100   a  has been measured, the transfer elements  21 ,  22  are moved to the fourth operating position P 4  ( FIG. 6 ) so that the second transfer elements  22  can remove the bodies  100   b  from the housings  17  of the gripping elements  7  and insert them completely into the respective first seats  233  of the support  223 . The operation of the weighing system  1  of the invention described above is the same also in the case of weighing whole capsules  100 . 
     Thanks to the transfer means  20  and the gripping elements  7  which receive and retain the bodies  100   a  of the capsules  100 , or the capsules  100 , by force, it is possible to transfer the bodies  100   a  very quickly, easily and efficiently from/to the moving device  201  and allow precisely and accurately weighing the bodies  100   a , both empty and containing the product, by means of the load cells  3  directly connected to the said gripping elements  7 . The first transfer elements  21  and the second transfer elements  22  are in fact linearly moved along the insertion/extraction direction E with limited strokes, therefore executable in very short times, between the various operating positions P 1 -P 4 . Therefore, the time necessary to carry out the entire weighing operation—which comprises the transfer of the body  100   a  from the moving device  201  to the gripping element  7  of the weighing cell  3 , its weighing on the latter and its transfer from the gripping element  7  to the moving device  201 —is very short and can be equal to the duration of the pause steps of an intermittent motion of the filling machine  1  also having a high speed or productivity. It is therefore possible to perform a total weight control of all the capsules  100  without decreasing the operating speed of the filling machine, which can be very high and equal to the operating speed of the known filling machines which perform a partial weight control of statistical type or a total weight control but with reduced measurement precision and accuracy. 
     Furthermore, the weighing system  1  of the invention, thanks to the connecting element  5  rigidly fixed to the corresponding loading stem  4  of the weighing cell  3  and slidably and elastically supporting the gripping element  7  through the interposition of the elastic means  6 , allows preserving the integrity and functionality of the weighing cell  3  during the transfer of the body  100   a  of the capsule  100  inside the housing  17  of the gripping element  7 . In particular, the gripping element  7  can be moved elastically in the end-stroke position B in which it abuts the abutment wall  10  of the weighing unit  2  so as not to act or transfer mechanical stresses, in particular axial thrusts, to the weighing cell  3 . 
     With reference to  FIGS. 7 and 8 , a variant of the weighing system  1  of the invention is illustrated, which can also be associated with a capsule filling machine  100 , which differs from the embodiment described above and shown in  FIGS. 1 to 6  for the shape and the position of the gripping element  107 . The latter extends from the weighing unit  102  upwards and has a housing  117  configured to receive a capsule  100 . More precisely, the housing  117  comprises a cavity open at the top, which extends transversely to a direction of movement L of the gripping element  107  between the measuring position A ( FIG. 7 ) and the end-stroke position B ( FIG. 8 ). The housing  117  is formed by a pair of opposite walls  117   a  converging towards the inside of the gripping element  107  and arranged to receive a capsule  100  ( FIG. 9 ). 
     The capsule  100  is inserted and then extracted from the housing  117  by transfer means of the weighing system  1  or of the filling machine of known type and not illustrated and described in detail. 
     The gripping element  107  comprises an upper part  107   a , which extends transversely and has the housing  117 , a central part  107   b  and a lower part  107   c  that have a substantially cylindrical shape. The connecting cavity  16 , which is arranged to receive the coupling portion  15  of the connecting element  5  with the interposition of the elastic means  6 , is realized in the lower part  107   c  which includes the abutment end  118 . 
     The gripping element  107  is connected to the connecting element  5  through the fixing element  14  (screw), which supports and guides the helical spring of the elastic means  6 . The threaded stem  14   a  of the screw  14  is screwed to the coupling portion  15 , while its head  14   b  is housed in a first seat  13  of the gripping element  107 . 
     In the normal operation of this variant of the weighing system  1  of the invention, the capsule  100  is positioned (with an established and reduced release force) by the transfer means in the housing  117  of the gripping element  107  which is connected and supported by the loading stem  4 , so as to allow the weighing cell  3  to weigh the capsule  100 . 
     If for accidental and unforeseen causes, malfunctions, anomalies, etc. the transfer means exerts an excessive force or thrust on the gripping element  107  in releasing the capsule  100  in the housing  117 , the gripping element is moved along the direction of movement L from the measuring position A to the end-stroke position B. In in this position, the helical spring  6  is compressed and the gripping element  107  abuts the abutment wall  10  of the weighing unit  102 , so as not to transfer mechanical stresses, in particular axial thrusts, to the weighing cell  3 . 
     When the capsule  100  is released by the transfer means in order to be weighed, the gripping element  7 , no longer subject to excessive force or thrust, is brought back to the weighing position A by the helical spring  6  so as to be spaced from the abutment wall  10  and fully supported by the loading stem  4  of the weighing cell  3  to allow the capsule  100  inserted in the housing  117  to be weighed accurately and precisely, without interference. Also in this case, since the displacement d of the gripping element  107  between the weighing position A and the end-stroke position B—thanks to the intervention of the helical spring (suitably sized) which is compressed—does not cause a displacement of the loading stem  4  of the weighing cell  3 , the latter does not remain damaged or altered by the positioning of the capsule  100  in the gripping element  107  regardless of the abnormal and high positioning speeds and forces of the transfer means. 
     With reference to  FIG. 10 , a filling machine  200  for capsules is shown which comprises a plurality of operating stations  220 ,  221 ,  224  for performing operations on the capsules  100 , a moving device  201  provided with a plurality of supports  223  with respective seats  233 ,  234  for housing and moving the capsules  100  in sequence through the operating stations  220 ,  221 ,  224  and at least one weighing station  209  for weighing the bodies  100   a  of the capsules  100  and which comprises the weighing system  1  of the invention. The moving device  201  comprises a carousel rotatable about a vertical axis of rotation Z and provided with a plurality of supports  223 , each of which is formed by a first support element  231 , having a plurality of first seats  233 , intended to house the bodies  100   a  of the capsules  100  and a second support element  232 , having a plurality of second seats  234  intended to house the caps  100   b  of the capsules  100 . 
     The plurality of operating stations comprises, for example, a filling station  221  arranged to dispense and dose a product in the bodies  100   a  of the capsules  100 ; the weighing station  209  is positioned downstream of the filling station  221 , with reference to a direction of movement M of the capsules  100  in the filling machine  1 , so as to measure the weight of the bodies  100   a  containing the product. 
     The filling machine  1  can also comprise an initial weighing station  210  provided with a respective weighing system  1   e  positioned upstream of the filling station  221 , with reference to the direction of movement M, so as to measure the weight of the empty bodies  100   a.    
     In this embodiment of the filling machine  200 , a feeding and opening station  220 , in which the caps  100   b  are removed and separated from the respective bodies  100   a , is positioned upstream of the initial weighing station  210 , while a capsule closing station  224 , in which the caps  100   b  are reapplied to the respective bodies  100   a  so as to close the capsules  100  again, is positioned downstream of the weighing station  209 . 
     The filling machine  1  of the invention further comprises a processing unit  250  connected to the weighing station  209  and to the initial weighing station  210  and configured to receive data relating to the measured weights and to calculate the net weight of the product dosed in each capsule  100  or respective body  100   a . In the case of a non-compliant capsule or respective non-compliant body—in that it contains a quantity of product with a weight outside the allowed tolerance range—the processing unit  250  is thus able to perform self-regulation of the dosing parameters (feedback control), reject the non-compliant capsules, generate an alarm signal.