Patent Publication Number: US-11040378-B2

Title: Dosing apparatus for powder products

Description:
BACKGROUND 
     Field 
     The invention relates to apparatuses for dosing products inside containers and in particular it relates to a dosing apparatus arranged for dosing, in an automatic packaging machine, a powder product inside containers and capable of being easily washed and sterilized. The invention also relates to a method for cleaning, in particular washing, the aforesaid dosing apparatus. 
     Description of the Related Art 
     In the automatic packaging machines known and used in the pharmaceutical, cosmetics and food sectors for filling containers with powder products, the use of dosing apparatuses of the volumetric type provided with a metering screw or Archimede&#39;s screw arranged to take the product out of a reservoir, or a hopper, and to dose it inside containers is known. The metering screw has in fact one helicoidal groove along a respective longitudinal development axis, that defines a pass-through cylindrical duct, wherein said metering screw is inserted with a little play, one cavity for containing and moving the product, having a precise and established volume for unit of length or pace. Thereby, by rotating the metering screw about the longitudinal axis of a determined angle, it is possible to move ahead for a corresponding stroke, a defined and precise dose of product which outflows through a terminal aperture of the cylindrical duct and falls inside the underlying container. 
     The sizes and the shape of the metering screw (internal and external diameters, pace of the helicoidal groove) are selected according to the dosage to be carried out in the containers and the type of powder product to dose. 
     The rotation motion of the metering screw is usually intermittent and coordinated with the forwarding motion of the containers in the packaging machine. 
     The metering screw is set to rotate, directly or by interposition of a speed reducer unit, by a rotary engine, usually electric, arranged inside the dosing apparatus or the packaging machine. 
     Inside the hopper a mixing element rotating around the metering screw may be provided, that provides to mix and make more sliding the powder product that the metering screw takes out and conveys outwardly through the pass-through cylinder duct. 
     In the case of pharmaceuticals packaging, in particular for parenteral use, it is necessary as well as required by the pharmaceutical rules, that all the elements, components, parts and surfaces of the dosing apparatus that are in contact with the product (metering screw, cylindrical duct, hopper, mixing element, etc) are perfectly clean and sterilized in order not to prejudice the sterility of the dosing and packaging process. To this end, after each production lot, the dosing apparatus must be duly washed and sterilized, in particular in order to remove each residue or trace of the previously packed product. 
     Typically the dosing apparatus is detached from the packaging machine and separated from it, where it is dismounted in its single parts and components that can thus be washed and sterilized separately. Once washed and sterilized, the dosing apparatus is then mounted again on the packaging machine. 
     However, these procedures are very complicated, laborious and time consuming, especially if the packaging machine is provided with a containment insulator sealingly separating from a surrounding external environment, a volume inside the machine wherein the filling and packaging process occur, such volume having to stay integral and isolated even during the dismounting/mounting procedure of the dosing apparatus. 
     In order to solve such a drawback, in-place washing and sterilization systems and procedures are known, so called OP/SIP (Clean-In-Place/Sterilization-In-Place) processes providing the input of washing and sterilization fluids in sequence inside the dosing apparatus mounted on the machine. However these results are effective in case of dosing apparatuses for liquid products, since in the case of powder products, though they are watersoluble, due to the presence of elements with peculiar geometries and shapes as metering screws and mixers, the simple input of washing/sterilization fluids does not guarantee the necessary cleansing and sterility and in particular the total removal of residues and traces of product. 
     In fact, while in function, the powder products tend to accumulate and agglomerate, adhering to the surfaces of the parts and components of the apparatus, in particular inside the helicoidal grooves of the dosing metering screws. Furthermore, especially in case of small sizes metering screws for micro-dosage, due to the very small play between metering screw and respective cylindrical duct wherein it is inserted, the passage of the washing fluids is difficult and it is thus hard to obtain a proper and correct cleansing. 
     SUMMARY 
     An object of the present invention is improving the known dosing apparatuses that can be associated to an automated packaging machine for dosing a powder product inside containers. 
     Another object is implementing a dosing apparatus for powder products that can be cleaned, in particular washed, in a quick, complete and optimal way, with no need to be removed from the packaging machine and/or even partially dismounted, in particular subjected to an in-place washing process, so called CIP or WIP. 
     A further object is providing a dosing apparatus and a cleaning method that enable to completely remove the powder product from parts, elements and surfaces inside the apparatus, ensuring an accurate and complete washing. 
     In one first aspect of the invention a dosing apparatus according to claim  1  is provided. 
     In one second aspect of the invention a cleaning method for a dosing apparatus according to claim  9  is provided. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention shall be better understood and implemented referring to the enclosed drawings showing an exemplary and non-limiting embodiment, wherein: 
         FIG. 1  is a cross-section of the dosing apparatus of the invention in a cleaning configuration; 
         FIG. 2  is an enlarged detail of the apparatus of  FIG. 1  illustrating in particular one washing manifold; 
         FIG. 3  is an enlarged section of a connecting element of the apparatus of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1 to 3 , a dosing apparatus  1  is shown arranged for dosing a powder product inside containers in an automated packaging machine that can be used in the pharmaceutical, cosmetics or food sectors. 
     The dosing apparatus  1  comprises a hopper  2  provided with one or more inner cavities  3 , for example two being adjacent and placed side by side, each of which is arranged to contain the powder product and comprises a lower portion  4  having a supply duct  5  with a terminal aperture  5   a  for the outflow of the product to be dispensed into a container. 
     The apparatus  1  also comprises one or more metering screws  8 , for example two, each of which rotating about and extending along a respective rotation axis X inside a respective inner cavity  3  and a corresponding supply duct  5 . 
     More precisely, each inner cavity  3  of the hopper  2  comprises an upper portion  6  having substantially cylindrical shape and the aforesaid lower portion  4  having substantially conical shape and converging towards the supply duct  5 . The latter includes an internal pass-through seat  5   b , in particular cylindrical, arranged to receive an operative end  8   a  of the corresponding metering screw  8  and cooperating with the latter for dosing the product inside containers. 
     Inside each inner cavity  3  of the hopper  2  a respective mixing element  9 , of the known type and not herein described in detail, is also provided, which rotates about the corresponding metering screw  8 , in particular co-axially to its rotation axis X, and which provides to mix the powder product and make it more sliding. 
     The dosing apparatus  1  also comprises a washing manifold  20  provided with one or more inlet openings  21 , for example two, and equal in number to the number of metering screws  8  and of relative supply ducts  5 , and containing in its interior a sonotrode  50  of the known type, not illustrated in detail in the figures. 
     In one cleaning configuration C of the dosing apparatus  1 , the washing manifold  20  is connected to the hopper  2 , in particular sealingly coupling the inlet openings  21  to the respective supply ducts  5 , so as to receive and contain a washing liquid  35  introduced into the hopper  2 , in a cleaning procedure that is better described in the following description. 
     The washing manifold has, for example, a substantially cylindrical elongated shape and comprises an inner compartment  26  arranged to contain the sonotrode  50 . The latter can be activated in the cleaning procedure in order to generate, through alternate pressure waves  31  produced by the sonotrode  50  thereof, air or steam bubbles or cavities  30  of microscopic sizes in the washing liquid  35 . The aforesaid air or steam bubbles or cavities  30  propagate towards the inner cavities  3  through the supply ducts  5  and are intended for detaching and/or breaking apart, by imploding, the residues of powder products that adhere to the internal surfaces of the dosing apparatus  1 , in particular the surfaces of the metering screw  8 , in its helicoidal groove. 
     A supply unit  51  is connected to the sonotrode  50  to transfer a oscillating power to the latter. In the illustrated embodiment, the supply unit  51  too is contained inside the washing manifold  20  and comprises a high frequency electric wave generator and a converter or transducer, for example of the piezoelectric type, which transforms the electric waves into ultrasonic mechanical oscillations or vibrations transmitted to the oscillating part that is the sonotrode  50 . An amplifier or booster interposed between the converter and the sonotrode  50  and arranged for amplifying the width of the mechanical oscillations may also be provided. The sonotrode  50  ultrasonic mechanical vibrations generate the alternate pressure waves  31  in the washing liquid  35 . 
     In order to removably couple each inlet opening  21  with the respective supply duct  5  in the cleaning configuration C, a corresponding connection element  10  is provided. The latter comprises a first seat  11  arranged to sealingly receive a respective supply duct  5  and a first coupling portion  12  adapted to abut a second coupling portion  22  of a corresponding inlet opening  21  of the washing manifold  20 . The first seat  11  substantially comprises a pass-through cylindrical cavity provided with one or more second annular seats  13  capable of housing respective sealing gaskets  28  arranged to elastically abut an external wall  5   c  of the supply duct  5  so as to sealingly insulate the inside of the washing manifold  20  and thus of the hopper  2  in the external environment, when the supply duct  5  is inserted in the first seat  11  thereof and the connecting element  10  is fixed to the inlet opening  21 . 
     The first and second coupling portions  12 ,  22  form, for example, a known connection of the “Tri-clamp” type and are mutually reversibly lockable through a closing clamp  25 . The connecting element  10  also comprises a collecting compartment  14  substantially arranged around the first seat  11  and provided with an outlet opening  15  for the air bubbles  30 , which is connectable, in the cleaning configuration C, to the inner cavities  3  of the hopper  2  via a connecting tube  27 . 
     The washing manifold  20  comprises a first discharge opening  23  for the outflow of the washing liquid  35  during and/or after the washing procedure of the dosing apparatus  1  and one second discharge opening  24  for the outflow of the air possibly present in the washing manifold  20  during one filling step thereof with the washing liquid  35 . To this end, the first discharge opening  23  is made at the lower end of the washing manifold  20 , substantially opposite to the inlet openings  21  so as to allow the complete outflow of the liquids by gravity from the washing manifold  20  mounting the latter on the hopper  2  with an inclination comprised between 1° and 5°, in particular 2°, with respect to a horizontal plane. 
     Differently, the second discharge opening  24  is formed at an upper end of the washing manifold  20  to enable (with the manifold mounted tilted) the air outflow and thus to prevent the formation of air bubbles or bags inside the washing manifold  20  thereof during its filling with the washing liquid  35 . 
     The sonotrode  50  and the power supply unit  51  connected thereof are completely inserted inside the inner compartment  26  of the washing manifold  20 . In particular, the sonotrode  50  is arranged below the supply ducts  5  and has a longitudinal axis Y transverse to the rotation axis X of the metering screw  8 . Preferably, the sonotrode  50  is arranged with its own longitudinal axis Y lying on a vertical plane passing through the rotation axis X of the metering screw  8 . In the preferred embodiment shown in the figures including two metering screws  8 , the longitudinal axis Y of the sonotrode  50  lies on a vertical plane passing through the rotation axis X of the two metering screws  8 . In general, for dosing apparatuses comprising a plurality of metering screws  8  and a corresponding plurality of inlet openings  21 , such metering screws  8  and inlet openings  21  are arranged above the sonotrode  50 , aligned along the longitudinal axis Y of the sonotrode  50  thereof. 
     The sonotrode  50  has such sizes and/or it is positioned inside the washing manifold  20  in such a way that the pressure waves  31  generated by it, oscillating with a sinusoidal motion along the longitudinal axis Y of the sonotrode  50 , have positive pressure peaks at the inlet openings  21  and thus at the supply ducts  5  as illustrated in  FIG. 2  and as better described in the following description. 
     The functioning of the dosing apparatus  1  of the invention provides, in a post-production cleaning or washing procedure, the connection of the washing manifold  20  to the hopper  2  in the cleaning configuration C of the  FIGS. 1-3 . Such connection is implemented coupling the supply ducts  5  of the hopper  2  to the respective inlet openings  21  of the washing manifold  20  through the connecting elements  10 . The latter are sealingly connected to the inlet openings  21  coupling the respective first and second coupling portions  12 ,  22  and stuck shut them by means of a closing clamp  25 . 
     The outlet openings  15  of the connecting elements  10  are thus connected to the inner cavity  3  of the hopper  2  through respective connecting tubes  27 . 
     In one ultrasounds washing step the hopper  2  and the manifold are completely filled with a washing liquid  35 . To this end, the first discharge opening  23  of the washing manifold  20  is closed, for example by a first respective valve, non illustrated, to avoid the outflow of the liquid, while the second discharge opening  24  is kept open for the time necessary to enable air to outflow from the washing manifold  20  and is thus closed by one respective second valve, not illustrated. 
     Once the filling with the washing liquid  35  has taken place and is completed, the sonotrode  50  is activated in order to produce, inside the washing manifold  20 , alternate pressure waves  31  which generate in the washing liquid  35  by cavitation, air or steam bubbles or cavities  30  that propagate upwardly towards internal cavities  3  of the hopper  2  through the supply ducts  5 . Air bubbles  30  are not stable and they implode within a short time generating localized high intensity shock waves that are able to detach and/or break apart residues and/or product agglomerates adhering to the internal surfaces of the dosing apparatus and in particular to the surfaces of the metering screws  8  and of the internal pass-through seat  5   b  of the supply duct  5 . 
     It must be noted that the sizes and/or the position of the sonotrode  50  inside the washing manifold  20  are such that the pressure waves  31  generated by the sonotrode  50  thereof and oscillating with sinusoidal motion along a longitudinal axis Y of the latter have positive pressure peaks at the inlet openings  21  and therefore at the supply ducts  5 . In other words, the metering screw  8  (and consequently the respective inlet openings  21 ) are arranged vertically above portions of the sonotrode  50  that generate positive pressure peaks of the pressure waves  31 . Thereby, the cavitation effect and the air bubbles formation  30  are more intense at the aforesaid supply ducts  5  which are affected during the functioning by a significant flow of the aforesaid air bubbles  30 . 
     The collecting compartment  14  inside each connecting element  10 , connected through the outlet opening  15  and the connecting tube  27  to the inner cavity  3  of the hopper, prevents the formation, at the terminal opening  5   a  of the supply duct  5 , of a barrier or cushion of air bubbles  30  which would prevent the latter ones from moving up through the internal pass-through seat  5   b . More precisely, the collecting compartment  14  conveys a part of the air bubbles  30  towards the inner cavity  3 , the remaining part thus being able to rise upwards through the supply duct  5 . Inside the supply duct  5  a part of the air bubbles  30  implodes detaching and breaking apart, thanks to the shock waves generated this way, the residues of product possibly existing on the surfaces of the metering screw  8  and of the internal pass-through seat  5   b . A remaining part of the air bubbles  30  further moves up along the supply duct  5  in the respective inner cavity  3  to implode affecting a central portion of the metering screw  8  and a terminal portion of the mixing element  9 . 
     Similarly the air bubbles  30  that reach the inner cavity  3  through the connecting tube  27  affect and implode against the internal walls of the inner cavity  3  and against a central portion of the mixing element  9  thus contributing to detach and/or break apart the residues of product possibly existing of the surfaces of such elements. 
     In order to facilitate the rise along the supply duct  5  of the air bubbles  30  generated by the sonotrode  50 , the respective metering screw  8  may be rotated about its own rotation axis X with a rotation direction opposite to the one used in the dosage of the product, that is such to push the air bubbles  30  towards the inner cavity  3 . 
     In order to facilitate the implosion of air bubbles  30  generated in the washing liquid by the sonotrode  50 , the hopper  2  and the washing manifold  20  are sealingly insulated from the external environment and subjected to an internal pressure higher than the atmospheric pressure. 
     After a predefined time lapse the sonotrode  50  is deactivated and the hopper  2  and the washing manifold  20  are emptied by opening the first discharge opening  23  of the manifold acting on the respective first valve. 
     The washing procedure may envisage, before the ultrasounds washing step, a preliminary washing step wherein the washing liquid is introduced inside the hopper  2 , for example through one or more spray-balls, and is made flow through the inner cavities  3 , the supply ducts  5  and the washing manifold  20  from which it outflows through the first discharge opening  23  of the manifold kept open by the first valve. The flow of washing liquid continues for a defined time lapse through the dosing apparatus  1  to remove the greatest part of the residual powder product after production is completed. In particular, such washing type enables to remove the product out of the internal cavities  3  of the hopper  2  and the greatest part of the product inside the helicoidal grooves of the metering screws  8 . 
     Once the ultrasound washing step is over, other washing cycles or steps of the dosing apparatus  1  may be performed (for example conveying washing liquid through the aforesaid first discharge opening  23  of the manifold towards the hopper  2 ) in order to complete the washing procedure. 
     Once the washing procedure is completed, a sterilization procedure (SIP) may be carried out, for example through steam, by means of known ways and systems. 
     Thanks to the use of the washing manifold  20  internally provided with the sonotrode  50 , the dosing apparatus  1  of the invention can thus be cleaned, in particular washed, in a quick, complete and optimal way with no need to be removed from the packaging machine and/or be dismounted even only partially. The washing manifold  20  in fact can be mounted rapidly and easily on the hopper  2 , in particular introducing the supply ducts  5  into the first seats  11  of the respective connecting elements  10  hooked to the inlet openings  21  of the manifold  20 . The connecting tubes  27  too are easily mounted connecting the outlet openings  15  of the connecting elements  10  to the internal cavities  3  of the hopper  2 . 
     Demounting the washing manifold  20  from the hopper  2  is equally quick and easy. 
     The use of the sonotrode  50  allows to remove completely the powder product from parts, elements and surfaces inside the apparatus, in particular at the dosing metering screws and at the relative supply ducts, thus ensuring an accurate and complete washing. 
     In fact the sonotrode  50 , when activated, generates in the washing liquid inside the manifold  20 , alternate pressure waves  31 , which generate, substantially by cavitation, air or steam bubbles or cavities  30 . The air or steam bubbles or cavities  30  propagate in particular in the supply ducts  5  and, imploding therein, they create localized high intensity shock waves capable of detaching and/or breaking apart possible residues and/or product agglomerates adhering to the internal surfaces of the dosing apparatus and in particular to the surfaces of the metering screws  8  and of the internal pass-through seat  5   b  of the supply duct  5 . 
     The method according to the invention for cleaning the above mentioned dosing apparatus  1  comprises the following steps:
         connecting the washing manifold  20  to the hopper  2  by sealingly coupling a supply duct  5  of the latter to a respective inlet opening  21  of the washing manifold  20 ;   filling the hopper  2  and the washing manifold  20  with a washing liquid  35 ;   activating the sonotrode  50  inside the washing manifold  20  to produce alternate pressure waves  31  capable of generating in the washing liquid  35  air bubbles or cavities  30  that propagate towards the inner cavities  3  of the hopper  2  through the supply duct  5  and that, by imploding, create shock waves adapted to detach and/or break apart powder product residues and/or agglomerates adhering to internal surfaces of the dosing apparatus  1 , in particular to the surfaces of the metering screws  8 .       

     The method further provides that during the driving of the sonotrode  50 , the hopper  2  and the washing manifold  20  are sealingly insulated from an external environment and set at an internal pressure higher than an atmospheric pressure to facilitate the implosion of said air bubbles  30 . 
     During the driving of the sonotrode  50 , rotating each metering screw  8  about its own rotation axis X in its respective supply duct  5  is also provided, so as to facilitate a moving upwards of the air bubbles  30  through the supply duct  5  towards the inner cavity  3 . 
     The method also provides positioning the sonotrode  50  in the metering screw  8 , before it is activated, in such a way that pressure waves generated by the sonotrode  50  and oscillating with sinusoidal motion along a longitudinal axis Y thereof have positive pressure peaks at the inlet opening  21  and at the supply ducts  5 , in order to obtain a stronger formation of air bubbles  30  at the aforesaid supply ducts  5  and relative metering screws  8 . 
     According to the method, making a washing liquid flow through the hopper  2  and the washing manifold  20  to washing and at least partially remove said residues of powder product before the filling is optionally provided.