Abstract:
An apparatus for forming a thermoplastic container from a cylindrical preform and for delivering a predetermined volume of a beverage component into the container. The apparatus includes: a mold defining a shape of the container; a member configured to inject at least one beverage component into a recess in the preform so as to promote expansion of the preform inside the mold into the shape of the container, the member being further configured to inject the at least one beverage component in a first volume intentionally greater than the predetermined volume; and the member also being configured to remove a fraction of the first volume of the beverage component until a second volume of beverage component remaining in the container is equal to the predetermined volume.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a divisional of U.S. application Ser. No. 13/002,199, which is a U.S. national phase application of international application no. PCT/EP2009/058236, filed Jul. 1, 2009. The entire disclosures of the above applications are incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to the field of manufacturing containers made of a polymer material, especially a polyester. More particularly, it relates to the field of manufacturing polyester bottles, preferably polyethylene terephthalate (PET) bottles containing a liquid, preferably water and especially mineral water. 
       BACKGROUND 
       [0003]    For many years, the PET bottles usually found on the market have been manufactured by the blow molding or stretch-blow molding of PET preforms using compressed air. 
         [0004]    A preform usually takes the form of a cylindrical tube closed at one of its ends and open at its opposite end. The open head of the preform corresponds to the neck of the container. During the conventional process for manufacturing containers from preforms, the preforms are slipped onto the cylindrical mounts of a continuous conveyor chain, which thus transports the preforms through an oven, essentially formed by a straight section bordered on each side by radiative heating means, so as to temperature-condition the plastic for the subsequent stretch-blow molding step. 
         [0005]    The hot preform is then taken off and transported into a mold of a blow molding machine. The transport movement, performed for example by a transfer arm, is coordinated with that of the blow molding machine, which is generally produced in the form of a rotary carousel that rotates continuously about its vertical axis and carries, on its periphery, a series of identical molds. Thus, the preform is placed in the mold immediately after it has been opened and the previously formed container has been removed. 
         [0006]    The preform is heated beforehand so as to be in the mold at a temperature above the glass transition temperature (about 100° C.) so as to enable it to be formed by stretch-blow molding. The temperature of the preform at the end of the heating step is slightly above that required inside the mold of the blow molding machine, so as to take into account the cooling that takes place over the distance that exists between the heating site and the blow-molding site. Thanks to the simultaneous presence of several molds, such a blow molding machine can produce containers at very high rates, of around 1000 to 2000 bottles per hour per mold, i.e. around several tens of thousands of units per hour. 
         [0007]    The stretch-blow molding takes place by stretching using a metal rod and by injecting air at pressures ranging from 3 to 40 bar (3.10 5  Pa to 4.10 6  Pa). The air is injected through a nozzle, the end of which is introduced through the opening in the head of the preform. 
         [0008]    In general, the pressures then exerted on the injected beverage are high, since the industrial process requires high rates. The usual practice is for the volume of beverage introduced into the containers to be above the displayed volume for the container, in so far as it is possible to finalize the contents with a volume greater than the stipulated volume, whereas the reverse is not possible. 
         [0009]    However, such a situation is hardly satisfactory as there is consequently a loss of food product for the manufacturer, and also a lack of precision in the match between the contained volume value and the reality of this volume, bottle by bottle. 
       SUMMARY 
       [0010]    Within this context, the technical problem solved by the present invention is to devise an industrial process that guarantees the stipulated volume for the type of filling, in a simple and economically acceptable manner. 
         [0011]    For this purpose, the Applicant proposes a method of delivering a predetermined volume of a beverage component into a thermoplastic container formed from a heated preform (for example an approximately cylindrical preform) positioned in a mold, the method including a step of injecting at least some beverage component into a recess in the preform so as to promote expansion of the preform inside the mold, the mold defining the shape of the container, a volume of beverage component introduced during the injection step being at least equal to said predetermined volume, and, in addition, the method includes a step of sucking out a fraction of said volume of beverage component introduced until the volume of beverage component remaining in the container is approximately equal to said predetermined volume. 
         [0012]    The method thus defined makes it possible to guarantee the intended volume for the type of container defined by the mold within the context of an integrated industrial process. 
         [0013]    The suction step is preferably carried out by means of a suction pump and a volumetric sensor. The injection step is preferably carried out by means of a pressurizing actuator and a volumetric sensor. 
         [0014]    Preferably, the injection step includes a substep of longitudinally stretching the preform by a stretch rod, said stretch rod being hollow, and the suction step comprises sucking out some of the beverage via said hollow stretch rod. 
         [0015]    This has the advantage that the method is implemented in an integrated manner. 
         [0016]    Advantageously, the method includes a step of recirculating at least part of the beverage sucked out during the suction step. 
         [0017]    The recirculation may be performed in the injection circuit, thereby minimizing beverage losses. 
         [0018]    According to one embodiment, provision is also made for the suction step to comprise suction by means of a vacuum pump. 
         [0019]    Advantageously, the injection step includes a sub-step of injecting at least some beverage via a hollow stretch rod that is designed to stretch a thermoplastic preform and is connected to a beverage inlet. 
         [0020]    According to a preferred feature, the same stretch rod serves for injecting beverage and for sucking out a fraction of said volume of beverage. 
         [0021]    According to one feature, which may be combined with the previous ones, the hollow stretch rod has an adapted profile in order to minimize the turbulence in the beverage during the step of injecting at least some beverage via the hollowing stretch rod. 
         [0022]    Said profile may include an internal profile, an external profile or a combination of an internal profile and an external profile. A person skilled in the art will appreciate that the characteristics of the surfaces are adapted, and they prevent the formation of turbulence. 
         [0023]    The beverage is injected in amounts of about 500 ml in 0.2 s. The adapted profile minimizes the turbulence, thereby making it possible to obtain a more stable process, with wider operational windows. 
         [0024]    Preferably, the injection is carried out by means of a bell-shaped filling head. 
         [0025]    This makes it possible to reduce the risks of the thermoplastic container necks rupturing, since they are subjected to high pressures during the injection step. 
         [0026]    According to one advantageous aspect, the stretch rod is designed in such a way that its internal volume is optimized so that said fraction of the beverage volume is reduced. 
         [0027]    Preferably, the fraction of the beverage volume is reduced to the internal volume of the neck. 
         [0028]    According to one embodiment, the injection step includes a step of injecting at least some beverage through the inside of the stretch rod and through an orifice around the stretch rod. 
         [0029]    Indeed, it is also advantageous for the injection step to comprise a step of injecting a first beverage component and a step of injecting a second beverage component. Under these circumstances, which have a particular advantage from the industrial standpoint, it is only in the bottle that the final preparation of the beverage can take place. 
         [0030]    Most particularly advantageous is the solution whereby the injection of the first beverage component comprises injection through the inside of the stretch rod and the injection of the second beverage component comprises injection through an orifice around the stretch rod. 
         [0031]    The invention also relates to a device for delivering a predetermined volume of beverage into a thermoplastic container formed from an approximately cylindrical heated preform positioned in a mold, characterized in that the device comprises means for injecting at least some beverage into a recess in the preform so as to promote expansion of the preform inside the mold, the mold defining the shape of the container, a volume of beverage introduced during the injection step being at least equal to said predetermined volume and the device comprising, in addition, means for sucking out a fraction of said volume of beverage component introduced until the volume of beverage remaining in the container is approximately equal to said predetermined volume. 
         [0032]    Advantageously, this device may include means suitable for carrying out the respective intended steps of the method, taken separately or in combination. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0033]    The invention will now be described in detail with reference to the appended figures, which relate to exemplary embodiments. 
           [0034]      FIG. 1  shows a general diagram of an installation suitable for operating with the invention. 
           [0035]      FIG. 2  is a schematic diagram of another installation embodying the principles of the present invention. 
           [0036]      FIG. 3  shows a bell-shaped nozzle end-piece used within the context of the invention. 
           [0037]      FIG. 4  shows the monitoring of the formation of a mineral water bottle according to one example of the use of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0038]    The embodiment given here by way of example relates to a process for manufacturing PET mineral water bottles from a heated preform. The preform has the shape of a cylindrical tube closed at its lower end. The open head of the preform corresponds to the throat or neck of the bottle, onto which a closure cap is screwed. 
         [0039]    Referring to  FIG. 1 , a stretch rod  10  is inserted into a compressed-air actuator  15 . The stretch rod  10  is generally controlled by an air actuator associated with a cam, which gives it a longitudinal movement (represented by an arrow). It is also possible to use a stretch motor. 
         [0040]    The compressed-air actuator  15  comprises a control cylinder  17  controlling an injection head  18 , through which the stretch rod  10  passes. The injection head  18  is connected to the neck  20  of a PET preform placed in a mold (not shown), which preform, after being expanded, takes on the shape of a mineral water bottle, this shape being determined by the wall of the mold. 
         [0041]    The actuator  15  comprises three chambers, the upper two chambers  15   a  and  15   b  being filled with compressed air. Between these upper two chambers  15   a,    15   b , a piston wall  19  slides in a direction parallel to the stretch rod (the  30  displacement being represented by an arrow). The stretch rod  10  passes through the center of this wall  19 . 
         [0042]    The compressed-air actuator also includes a lateral inlet  30  for the beverage, here mineral water, connected to a third chamber  15   c  of the actuator, this being the bottom chamber. The beverage is fed in via a line  32 . 
         [0043]    An external mineral water inlet feeds the liquid via the remote end of this line  32  into a first valve  34 , which is connected to the opening of a single-chamber filling cylinder  40  comprising a piston  42  controlled by a filling motor (movement of which is represented by an arrow). This motor imparts a longitudinal movement on the piston in the single chamber of the filling cylinder  40 . 
         [0044]    On the line  32  there is a second valve  36 , which is in series behind the first valve  34  and the opening of the filling cylinder  40 . The line  32  then runs into the bottom chamber  15   c  of the compressed-air actuator  15 . 
         [0045]    The bottom chamber  15   c  of the compressed-air actuator is penetrated by the control cylinder  17 , which controls the filling head  18 , the internal volume of which emerges through the lower outlet of the compressed-air actuator  15  and through the filling head  18 . The control cylinder has a lateral opening  25  allowing the beverage to circulate between the bottom chamber  15   c  of the actuator  15  and the inside of the control cylinder  17 . 
         [0046]    The stretch rod  10  itself passes through the control cylinder  17  as far as the filling head  18  and the neck  20  of the bottle preform. 
         [0047]    Referring to  FIG. 2 , showing an alternative embodiment, a pressurizing actuator  100  increases the pressure of the beverage in the beverage feed line  110 . A volumetric sensor  120  allows the volume injected through the line  110  to be monitored. The beverage is introduced into the nozzle  130  through the line  110 . 
         [0048]    The stretch rod  140  is introduced along the axis of the nozzle  130 . 
         [0049]    A suction pump  150  is attached to a line  170  connected via a volumetric sensor  160  to the nozzle  130 . 
         [0050]    The nozzle  130  is positioned facing the mold (not shown) in which the PET preform, to be expanded and filled with beverage, here mineral water, is positioned. After the expansion phase, a PET water bottle  180  is formed. 
         [0051]    Referring to  FIG. 3 , a bell-shaped nozzle end-piece  500  according to a preferred embodiment is shown. The internal and external pressures on either side of the circumference of the neck of the preform (i.e. on the external surfaces  510  of the neck and on the internal surfaces  520  of the neck) are identical, owing to the presence of a passage  505  connecting the volumes on either side of the circumference, inside the nozzle. During filling, sealing is provided by the flange  530  on the preform. Thanks to this device, there is no risk of the neck of the preform deforming while a pressurized fluid is being injected by the nozzle. 
         [0052]    According to another embodiment, a nozzle end-piece holds the external surfaces  510  of the neck of the preform in such a way that when a pressurized fluid is injected via the top of the nozzle into the recess of the preform, the pressure exerted on the internal walls  520  of the neck of the preform by the fluid is compensated for by the holding by the walls of the bell-shaped nozzle end-piece. The neck of the preform therefore does not deform, despite the high pressure. 
         [0053]      FIG. 4  shows the variation over time of the position  101  of the stretch rod and the position  102  of the filling actuator controlling the inflow of the mineral water into the expanded preform. 
         [0054]    The horizontal axis represents the time, the left-hand vertical axis represents the position of the stretch rod and the right-hand vertical axis represents the volume of water introduced into the expanded preform, this being proportional to the position of the filling actuator. 
         [0055]    During a first part of the process, from 0 to 250 ms, the stretch rod advances at an essentially constant rate, according to a preferred embodiment. However, according to another embodiment, during a first phase  110  of the process, in particular from 0 to 150 ms, the stretch rod advances at an increasing speed due to a positive acceleration. During a second phase  115  of the process, from 150 ms to 250 ms, the stretch rod advances with a negative acceleration, the speed decreasing until it becomes zero at 250 ms. However, it will be understood that the changes in speed must be sufficiently gentle to ensure regular and reliable stretching of the thermoplastic. 
         [0056]    250 ms after the start of the process (reference  103 ), the stretch rod has reached its final position P f , from which it no longer moves. 
         [0057]    At the same instant, the filling actuator has introduced a volume Vi of mineral water into the expanded preform. The volume introduced from the start of the process (therefore between 0 ms and 250 ms) has progressively increased, with a progressive increase in the flow rate (filling actuator displacement acceleration). 
         [0058]    During the moments that follow, which constitute a third phase  120  of the process, up to 320 ms, the total volume of water introduced is constant, the flow rate being invariant. Next, the volume suddenly decreases by a small fraction (around 4%) over a period of 40 ms. 
         [0059]    From this instant on, the total volume introduced stabilizes around the value V2, which is finally reached after a few oscillations, the flow rate of liquid being introduced being zero. 
         [0060]    A few instants later, starting from 450 ms after the start of the process (reference  104 ), the filling actuator has reached a final position, from which it no longer moves. At this moment, it has introduced a volume V2 of mineral water into the expanded preform. The volume V2 is greater than V 1 , but less than twice the volume V 1 . 
         [0061]    During the method of using the device described, the temperature of the preform is brought beforehand to a value between 50° C. and 130° C., or even between 75° C. and 100° C. In the preferred embodiment, this value is 95° C., the plastic used being PET. 
         [0062]    The rod has a speed of between 0.5 and 3.0 m/s −1 , or even between 1.0 and 5 m/s −1 . In the preferred embodiment, this value is 1.6 m/s −1 . 
         [0063]    The temperature of the beverage is brought beforehand to a value 25 between 1° C. and 120° C., preferably between 10° C. and 90° C. In the preferred embodiment, this value is 30° C. 
         [0064]    The longitudinal stretch ratio of the thermoplastic is between 2 and 5 or even between 2.5 and 4. In the preferred embodiment, this value is 3.5. 
         [0065]    The radial stretch ratio of the thermoplastic is between 2 and 7, or even between 3 and 4.5. In the preferred embodiment, this value is 4. 
         [0066]    The thermoplastic is chosen from the group consisting of polyethylene terephthalates, polypropylenes, polyethylenes, polycarbonates, polystyrenes, polylactic acids, polyvinyl chlorides and combinations thereof. In the preferred embodiment, it is PET. 
         [0067]    The temperature of the mold is at least 50° C. below the melting point of the thermoplastic, which in the case of PET is 230° C. Preferably, this 5 temperature is maintained below 100° C. In the preferred embodiment, the temperature of the mold is equal to the ambient temperature. 
         [0068]    Of course, the invention is not limited to the embodiments described and illustrated by the appended drawings; rather it extends to all variants that can be envisaged by a person skilled in the art within the scope of the claims.