Method for forming and filling a container using a liquid having a swirl flow

A method for simultaneously forming and filling a container by injecting a pressurized liquid in a preform. The method includes placing the preform in a mold and injecting the pressurized liquid into the preform such that the liquid expands the preform and urges the wall of the preform against the wall of the molding cavity forming the preform into a container and the container is filled with liquid. A swirl imparting element extends in the injection flow and imparts a swirl flow on the pressurized liquid such that the pressurized liquid applies a centrifugal force on the wall of the preform during forming and filling of the preform, thereby promoting a radial expansion of the preform in radial planes substantially perpendicular to the preform axis.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a method for simultaneously forming and filling a container by injecting a pressurized liquid in a preform.

The invention also relates to a forming station for simultaneously forming and filling a container by injecting a pressurized liquid in a preform according to such a method

In the application, “liquid” has a physical meaning. It designates any incompressible and able to flow medium. The liquid can have a low viscosity (like water or alcohol), a medium viscosity (like edible oil or soup), or a high viscosity (liquid detergent, soap, shampoo, ketchup, mustard). The liquid can be homogeneous or not homogeneous (including fruit pulp or bits of foodstuff), it can be Newtonian or non-Newtonian. It is not limited to foodstuff. The incompressible liquid may be for example water, or other beverages, foodstuff such as ketchup, mayonnaise, edible oil, yogurts, home or personal care products, medical fluids, fuels, hydraulic oil, operating fluids, and the like.

BACKGROUND

In the field known as “hydroforming”, it is known to use a pressurized liquid injected inside a preform placed in a mold to shape a container according to the shape of the mold and fill said shaped container with the liquid at the same time. Advantageously, the injected liquid is the end product contained in the container, i.e. the product which is intended to be provided to a consumer using the container.

For allowing the deformation of the preform into a container, the preform is heated at a temperature greater than the glass transition temperature and lower than the crystallization temperature of the material of the preform such that the preform is placed in a malleable state and is able to expand up to the shape of the container to be produced.

In some application, the liquid injected in the preform is generally injected at a temperature lower than the glass transition temperature of the preform material. The temperature of the injected liquid is for example the ambient temperature, typically from 5° C. up to 50° C. while the glass transition temperature is for example over 75° C. for PET.

The preform is expanded in an axial direction, i.e. along the axis of the preform, and in radial planes, i.e. perpendicularly to the axial direction, according to a bi-orientation ratio, or stretch ratio, which is defined by the following equation:

Wherein BOR is the bi-orientation ratio, D is the mean diameter of the container to be produced, d is the mean diameter of the preform, L is the half developed length of the container to be produced and l is the half developed length of the preform.

In order to obtain a container having good mechanical and gas/liquid barrier properties and presenting a satisfactory shape, the bi-orientation ratio has to be optimized.

In a hydroforming process, the axial expansion of the preform can be assisted by a stretch rod arranged to elongate the preform along its axis, but the radial expansion is promoted only by the injected liquid and can be insufficient in some areas in the preform. The liquid is generally injected in the direction of the preform axis, generally a vertical axis, and reaches the bottom of the preform first. Consequently, the bottom part of the preform is first expanded and the expansion of the preform occurs from bottom to top the container. Since during the liquid injection, the expanding preform cools down, the upper part of the container can be insufficiently expanded at the end of the liquid injection.

In this case, the bi-orientation ratio is not optimized and the shape of the produced container is not satisfactory.

One of the aims of the invention is to improve the radial expansion of the preform in order to optimize the bi-orientation ratio and ensure a better forming of the container.

Far from the above problem of forming performance, document US 2013/0074979 describes an apparatus for filling bottles. The apparatus comprises a liquid valve, a swirl body and a probe determining the fill level of liquid inside the bottle during filling. The swirl body imparts a swirl such that the liquid filling material flows along the inner surface of the container, avoiding a premature wetting of the probe by the liquid filling material before the desired fill level is reached.

SUMMARY OF THE INVENTION

To this end, the invention relates to a method for simultaneously forming and filling a container by injecting a pressurized liquid in a preform extending according to a preform axis, using a forming station comprising an injection nozzle and a source of pressurized liquid arranged to inject a pressurized liquid through an outlet of the injection nozzle, the method comprising the steps of:placing the preform in a mold having a molding cavity defining the shape of the container to be produced,placing the preform in liquid tight contact with the outlet of the injection nozzle,injecting the pressurized liquid from the pressurized liquid source into the preform through the outlet of the injection nozzle, the pressurized liquid flowing from the pressurized liquid source to the outlet along an injection flow, the liquid expanding the preform and urging the wall of said preform against the wall of the molding cavity such that the preform is formed into a container and said container is filled with liquid, anda swirl imparting element of the injection nozzle extending in the injection flow imparts a swirl flow on the pressurized liquid between the pressurized liquid source and the outlet such that the pressurized liquid applies a centrifugal force on the wall of the preform during forming and filling of the preform, thereby promoting a radial expansion of the preform in radial planes substantially perpendicular to the preform axis.

The inventor has discovered that placing a swirl imparting element within an injection nozzle of a forming station for simultaneously forming and filling a container with pressurized liquid produces a very surprising effect that was totally unexpected.

The apparatus for filling a bottle as described in US 2013/0074979 is a traditional filler wherein the liquid drops smoothly inside a bottle already formed while said bottle is full of air or gas. There is no, or almost no difference between the liquid pressure in the nozzle and the inner pressure in the container. The injection speed is therefore very low. The filling time can be for example comprised between 5 s and 20 s. The swirl body inserted in the injection nozzle of the traditional filler only deviates radially the liquid flow as to avoid wetting the probe too early. The swirl created by the swirl body only exists at the nozzle outlet. The injected liquid first reaches the vertical wall of the bottle and then slides down to the bottom of the bottle. The travel of the liquid along the vertical wall reduces or stops the swirl effect. Consequently, the liquid at the bottom of the bottle is almost quiet and stable. During the filling, the liquid level goes up smoothly up to its detection by the probe. This traditional filler with swirl body can generally be used for filling beer or carbonated beverages in order to separate the entry flow of that beverage and the exit flow of air or gas.

In a forming and filling station, the injection speed is very high. The forming and filling time could be 0.2 s because the container has to be formed before the preform temperature drops below the glass transition temperature of the preform material. Additionally, the inner volume of the preform is much smaller than the container inner volume, so the preform is filled with liquid almost immediately after the beginning of the filling. The surprising effect discovered by the inventor is that during the radial expansion of the preform up to the molding cavity, the whole volume of liquid inside the preform is dragged in rotation about the preform axis by the swirl generated at the injection nozzle outlet. Therefore, the rotating whole mass of liquid inside the preform creates a significant centrifugal force on the vertical wall of the preform. In the previously mentioned traditional filler, there is no, or almost no mass in rotation and very small injection speed, so there is no centrifugal force.

In the method of the invention, the existence of said centrifugal forces creates a very interesting technical effect. The centrifugal forces are applied in planes substantially perpendicular to the preform axis, i.e. in radial planes. Therefore, the radial expansion of the preform is not only due to an increase of liquid volume in the preform, like in a bubble expansion. The proportion of the radial expansion with respect to the axial expansion is modified due to the existence of a massive liquid rotation. Consequently, the shape of the obtained container is more satisfactory and the bi-orientation ratio is optimized. Furthermore, the injected liquid first hits the preform in a more even manner and not only at the bottom of the preform. Consequently, the expansion of the preform does not occur from bottom to top and the expansion of the upper part of the preform is improved since said expansion can occur before the material of the preform has cooled down.

According to other features of the method according to the invention:the preform is further expanded according to an axial direction extending along the preform axis, said axial expansion being promoted at least in part by a stretch rod of the injection nozzle, said stretch rod extending along the preform axis and being actuated to stretch the preform along said axis,the outlet extends along an injection axis substantially aligned with the preform axis, the swirl flow imparted on the pressurized liquid being arranged such that the pressurized liquid swirls around the injection axis according to a swirling slope,the swirling slope forms an angle comprised between 40° and 60° with the injection axis, andthe swirl flow is imparted on the pressurized liquid in the immediate vicinity of the outlet such that the liquid is swirling when it fills the preform.

Imparting the swirling flow close to the outlet allows making sure that the liquid will swirl inside the preform. Furthermore, since the outlet extends according to the injection axis, imparting the swirling flow close to said outlet allows precisely controlling the swirl around the injection axis, which would not necessarily be the case if the swirling flow was imparted in an area where the liquid does not flow in a direction parallel to the injection axis.

According to another feature of the method according to the invention, the swirl flow is arranged such that the radial expansion of the preform occurs substantially simultaneously along a major part of the height of the preform, measured according to the preform axis.

As explained previously, the method according to the invention allows forming the container in a more even manner which improves the final shape of the obtained container.

The invention also relates to a forming station for simultaneously forming and filling a container by injecting a pressurized liquid in a preform extending according to a preform axis, said forming station comprising a pressurized liquid source, a mold having a molding cavity and an injection nozzle comprising an outlet extending along an injection axis, said outlet being arranged to be placed in liquid tight contact with the preform, the forming station being arranged to inject a pressurized liquid from the pressurized liquid source into the preform through the outlet, the pressurized liquid moving from the pressurized liquid source to the outlet along an injection flow, wherein the injection nozzle further comprises a swirl imparting element extending in the injection flow, said swirl imparting element being arranged to impart a swirl flow to the pressurized liquid such that the pressurized liquid swirls around the preform axis when said pressurized liquid flows through the outlet.

The forming station according to the invention allows implementing the method described above.

According to other features of the forming station according to the invention:the swirl imparting element is placed in the vicinity of the outlet,the injection nozzle comprises a closing valve and a valve seat, said valve seat extending in the vicinity of the outlet, said closing valve being movable between a closed position wherein the closing valve is applied in a liquid tight manner against the valve seat to prevent the pressurized liquid from flowing through the outlet and an opened position wherein the closing valve is spaced from the valve seat to allow liquid to flow through the outlet,the closing valve comprises a control rod extending along the injection axis in the injection flow, said control rod comprising a sealing part, placed in liquid tight contact with the valve seat in the closed position of the closing valve, the swirl imparting element comprising a plurality of fins extending around the control rod across at least a part of the injection flow, said fins being oriented along a swirling slope forming an angle relative to the injection axis, andthe injection nozzle comprises a nozzle body defining the outlet and a nozzle chamber extending upstream of said outlet for temporarily receiving the pressurized liquid to be injected in the preform, the control rod extending and being movable inside said nozzle chamber, the fins extending from the nozzle body towards the control rod or from the control rod towards the nozzle body.

According to an embodiment, the swirl imparting element is attached to the closing valve and extends towards the wall of the nozzle body and according to another embodiment the swirl imparting element is attached to the wall of the nozzle body and extends towards the closing valve.

According to another feature of the forming station according to the invention, the cross-section in a radial plane of each fin extends from the control rod to the nozzle body or extend over only a part of the distance separating the control rod and the nozzle body.

According to an embodiment, the fins extend across the whole distance separating the closing valve from the wall of the nozzle body and, according to another embodiment, across a part of this distance only. In the first case, the swirling flow is imparted on the whole liquid flowing in the nozzle body. In the second case, the swirl imparting element offers less resistance to the flow of liquid, which is advantageous in case of more viscous liquids.

According to another feature of the forming station according to the invention, the swirl imparting element extends upstream or downstream of the sealing part of the control rod.

Placing the swirl imparting element upstream of the sealing part allows imparting the swirling flow at a location where the radial dimension of the inner body is larger. In this case, when the liquid flows into the preform, the liquid moves to a location having a smaller radial dimension, which causes the rotation of the liquid to accelerate when it enters the preform. Consequently, the centrifugal force imparted by the liquid can be increased. Placing the swirl imparting element downstream of the sealing part can be advantageous in terms of space requirement and of access to the swirl imparting device.

According to other features of the forming station according to the invention:each fin comprises an upstream end and a downstream end, the tangent of the upstream end being substantially parallel to the injection axis and the tangent of the downstream end extending along the swirling slope, the fin being arcuate between the upstream end and the downstream end, andtwo successive fins form an angle with the injection axis substantially comprised between 24° and 72°.

DETAILED DESCRIPTION OF THE INVENTION

In the following description, the terms “upper” and “lower” are defined relative to axis A, which corresponds to the axis of the container to be produced and which extends substantially vertically when the container is placed on its bottom.

In the application, the terms “upstream” and “downstream” are defined with respect to the direction of the flow of liquid circulating in the forming station.

The invention relates to the technical field of forming containers, such as bottles, for example beverage bottles containing water, carbonated water, carbonated soft drinks, Juices, Teas, energy drinks, alcoholic, non-alcoholic drinks or other type of liquids, such as personal or home care products, pharmaceutical, viscous food and non-food products such as for example and not limited to edible oil, ketchup, yogurt, motor oil.

More specifically, the invention relates to a method for producing a container from a preform2in a forming machine comprising at least a forming station4.

The machine is arranged to receive successive preforms2, each made of a thermoplastic material. The thermoplastic material is for example chosen among the polyesters, such as polyethylene terephthalate (PET), polyethylene naphthalene (PEN), polyethylene imine (PEI), polytrimethylene terephthalate (PTT), polylactic acid (PLA), polyethylene furanoate (PEF), or polyolefins, such as polyethylene low density (LDPE) or high density (HDPE), polypropylene (PP), or styrene based materials such as polystyrene (PS), or other polymers, such as polyvinyl chloride (PVC) or a mix of these materials.

Each preform2has for example the general shape of a test tube. Consequently, each preform2comprises a body6having the shape of a tube extending along a longitudinal axis, or preform axis, A and having a U shape in longitudinal cross-section, i.e. in an axial plane containing the preform axis A, as shown inFIG. 1. The preforms2have an open extreme part8and, at the other end, a closed extreme part10. The open extreme part8has for example the final shape of the neck12of the container to be shaped, meaning that the shape of the neck12will not be modified during the container forming process. The neck12defines an inner opening14extending along the longitudinal axis A and delimited by a wall with an external face for example provided with a thread allowing the container1to receive a cap by screwing. The closed extreme part10has for example a hemispherical shape. The above described shape is given as a non-restricting example and other shapes can be foreseen, for example another shape of the neck, without a thread, comprising or not an outer shoulder extending radially substantially perpendicular to the longitudinal axis A. The inner volume of the preform2is delimited by an inner wall15of the preform.

The preforms2can be produced at another location than the location of the forming machine, such that the preforms are stored and shipped together to the location of the machine.

The preforms are then successively loaded in the machine and transferred to a heating station. The heating station is conventional and will not be described in detail herein. The heating station is arranged to heat each of the successive preforms at a temperature comprised between the glass transition temperature and the crystallisation material of the thermoplastic material of the preform2such that the preforms2are placed in a malleable state in which they are able to be deformed under the influence of a pressure injected inside said heated preforms2. Alternatively, the preforms2can be produced at the same location than the location of the forming machine such that the injected preforms are transferred to the inlet of the forming machine. This allows reducing the energy required for heating the preforms before the forming step.

Each heated preform2is then transferred, for example by means of a transfer wheel, to a forming station4.

The forming station4is for example carried by a forming wheel rotating around a first axis substantially parallel to the longitudinal axis A. The forming and filling step, which will be described subsequently, can then be carried out during the rotation of the forming station4, which allows forming and filling several preforms2at the same time by providing several forming stations4on the wheel.

Each forming station4comprises a mold16arranged to receive a preform2and an injection nozzle18arranged to inject a forming liquid in the preform2received by the mold16, as shown inFIGS. 1 and 2. The forming liquid is a pressurized liquid coming from a pressurized liquid source20.

Apart from the swirl imparting element, which will be described subsequently, such a forming station4is conventional for a hydroforming machine.

The mold16defines a molding cavity22having the shape of the container1to be produced. The mold16comprises for example at least two parts movable relative to each other, between an opened position and a closed position. The two parts are for example hinged together and are movable in rotation relative to each other around an axis substantially parallel to the preform axis A. Each part of the mold16comprises a body comprising a hollow recess having the shape of a half bottle to be formed. According to a non-limiting example, the hollow recess of one part comprises a semi-cylindrical portion, closed at its lower end by a bottom surface having a shape of a semi-circle, and terminated at its upper end by a tapered, then semi-cylindrical collar of a shape substantially complementary to the shape of half of the body6of the preform2. The hollow recess of the other part of the mould is symmetrical to the hollow recess described above. In the opened position, the parts of the mould are separated from each other such that the preform2can be introduced between the two parts. In the closed position, the two parts are applied against each other to form a main part, such that the hollow recesses face each other and define together the molding cavity22having the shape of the container to be formed. The mold16could comprise more than two parts. For example a third part having the shape of the bottom of the container could be provided to define the molding cavity22with two parts having the shape of the body of the container. The third part or the two bottom surfaces of the two parts of the mold16define the bottom of the mold16.

The injection nozzle18for injecting the pressurized incompressible liquid in the preform2will now be described.

The injection nozzle18comprises an inlet24, an outlet26and a nozzle chamber28extending between the inlet24and the outlet26and placing the inlet24in fluidic communication with the outlet26.

The inlet24is placed in fluidic communication with the pressurized liquid source2, which comprises an incompressible forming liquid source30, for example a water reservoir, pressurizing means32adapted for pressurizing and transferring the liquid from the liquid source30to the inlet24at least one controllable predetermined pressure and appropriate tubing extending between the inlet24, the pressurizing means32and the liquid source30. According to the embodiment shown inFIG. 1, the pressurizing means32are formed by a pump. Alternatively, the injection means can also be formed by a conventional piston or by other appropriate means allowing controlling the pressure of the liquid injected in the preform. According to an embodiment, the pressure applied by the injection means is variable such that the liquid can be injected at different pressures in the preform2. By pressurizing, it is meant that the pressure in the liquid is brought to a pressure greater than the atmospheric pressure.

The outlet26is adapted to be placed in liquid tight fluidic communication with the opening14formed by the neck12of the preform2held by the mold16of the forming and filling station, and therefore with the inner volume of the preform2. By liquid tight fluidic communication, it is meant that when the outlet26is in fluidic communication with the inner volume of the preform2, the liquid flows only in the inner volume of the preform2and not outside the preform2.

The outlet26is for example formed by an opening of a nozzle body34, which comprises a wall defining the nozzle chamber28. The outlet26is in fluidic communication with the nozzle chamber28. The outlet26and the nozzle chamber28extend along an injection axis, which is substantially aligned with the preform axis A when the preform2is placed in the mold16, as shown inFIG. 1.

According to the embodiment shown inFIGS. 1 and 2, the nozzle body34comprises a movable part35movable inside a housing36of the nozzle body, in translation along injection axis A between a retracted position (FIG. 1) and an active position (FIG. 2). In the retracted position, the movable part35leaves room under the injection nozzle18to position a preform2in the mold16or to retrieve a formed container1from the mold16. In the active position, the movable part35placed against the neck12of the preform2with a liquid tight contact between the nozzle body34and the neck12of the preform2, such that the outlet26is in fluidic communication with the inner volume of the preform2. The nozzle chamber28of the nozzle body34for example comprises a hollow space including a regular cylindrical portion and a truncated cone or a pyramidal portion extending between the regular cylindrical portion and the outlet26of the injection nozzle. The diameter of the nozzle chamber28reduces progressively from the diameter of the regular cylindrical portion to the diameter of the opening in the conical portion.

According to the embodiment shown in the figures, the housing36further comprises a first upper compartment38arranged to receive actuation means40for moving the movable part35. The actuation means are for example pneumatic actuation means and for example comprise a piston, attached to the movable part35and hermetically separating the first upper compartment38into an upper part and into a lower part, each able to be filled with air. For moving the movable part between its retracted position and its active position, air is injected in the upper part of the first upper compartment38in order to increase the pressure in said upper part and to move the piston such that the volume of the upper part increases, while the volume of the lower part decreases. Conversely, for moving the movable part35between its active position and its retracted position, air is injected in the lower part of the first upper compartment38in order to increase the pressure in said lower part and to move the piston such that the volume of the lower part increases, while the volume of the upper part decreases. The inner volume of the nozzle chamber28is hermetically isolated from the first upper compartment38by appropriate sealing means.

The injection nozzle18further comprises a closing valve41for example formed by a hollow control rod42extending in the nozzle chamber28along axis A. The hollow control rod42comprises at its lower end, extending in the nozzle chamber28, a sealing part44, for example formed by a sealing ring. The sealing part44has a shape which is complementary to the shape of part of the conical portion of the nozzle body34, such that, when the sealing part44is applied against the wall of the conical portion, the sealing part44closes hermetically the nozzle chamber28and prevents liquid from flowing through the outlet26. The conical portion therefore forms a valve seat45arranged for receiving the sealing part44in a liquid tight manner. The valve seat45extends in the immediate vicinity of the outlet26. The valve seat45for example extends from the outlet26towards the cylindrical portion of nozzle body34.

The control rod42is movable in translation along injection axis A in the nozzle chamber28between an injecting position, shown inFIG. 2, wherein the sealing part44is spaced from the valve seat45and wherein the outlet26is in fluidic communication with the inlet24via the nozzle chamber28, and a sealing position, shown inFIG. 1, wherein the sealing part44is applied against the wall of the valve seat and hermetically closes the nozzle chamber28.

The housing36further comprises a second upper compartment46arranged to receive actuation means48for moving the control rod42. The actuation means are for example pneumatic actuation means and for example comprise a piston, attached to the control rod42and hermetically separating the second upper compartment46into an upper part and into a lower part, each able to be filled with air. For moving the control rod42between its injecting position and its sealing position, air is injected in the upper part of the second upper compartment46in order to increase the pressure in said upper part and to move the piston such that the volume of the upper part increases, while the volume of the lower part decreases. Conversely, for moving the control rod42between its sealing position and its injecting position, air is injected in the lower part of the second upper compartment46in order to increase the pressure in said lower part and to move the piston such that the volume of the lower part increases, while the volume of the upper part decreases. The first upper compartment38is hermetically isolated from the second upper compartment46by appropriate sealing means.

According to the embodiment shown in the figures, a stretch rod50extends inside the hollow control rod42, passes through the outlet26and extends in the preform2to assist in the axial deformation of the preform2into a container, as will be described subsequently. The stretch rod50is movable in translation along axis A in the hollow control rod42and is actuated by appropriate actuation means, for example a servo motor or a magnetic actuation means. The stretch rod50is movable in a fluid tight manner through the sealing part44thanks to appropriate sealing means extending between the hollow control rod42and the stretch rod50.

As will be described subsequently in greater detail, the liquid flowing from the liquid source30to the outlet26flows according to an injection flow.

The forming station4according to the invention further comprises a swirl imparting element52extending in the injection nozzle18between the pressurized liquid source20and the outlet26and arranged to impart a particular flow on the pressurized liquid, said particular flow being modified relative to the injection axis A, as will be described subsequently. More particularly, the swirl imparting element52is preferably placed in a part of the injection nozzle18which extends along the injection axis A.

In this case, the swirl imparting element52comprises a plurality of fins54extending around the injection axis A.

Each fin54extends between an upstream end56and a downstream end58, the upstream end56extending upstream of the downstream end58relative to the injection flow. The upstream end56extends substantially along the injection axis A, meaning that the tangent of the fin54at the upstream end is substantially parallel to the injection axis. The downstream end58extends along a swirling slope S, meaning that the tangent of the fin54at the downstream end extends along a slope S that forms an non-zero angle α with the injection axis A, as shown inFIG. 4. According to various embodiments, angle α is for example comprised between 40° and 60°. Between the upstream end56and the downstream end58, the fin54has an arcuate shape. The arcuate shape is for example such that the tangents to the fins change progressively from being parallel to the injection axis A at the upstream end56to extending along the swirling slope S at the downstream end58.

The fins54are for example arranged regularly around the injection axis A, meaning that the angle β between two successive fins54and the injection axis A is constant and that the fins54are regularly distributed around axis A, as shown inFIGS. 5 and 6. Angle β is for example comprised between 24° and 72°. In particular, angle β is for example equal to 36° when the swirl imparting element comprises 12 fins.

According to a first embodiment, shown inFIGS. 1 to 3, the swirl imparting element52is attached to the control rod42such that the fins54extend from the control rod42toward the nozzle body34. In this case, the swirl imparting element52is movable with the control rod42. The swirl imparting element52has for example the shape shown inFIG. 3and comprises a body60carrying the fins54and comprising a central bore62arranged to be placed around the control rod42. In this case, the swirl imparting element52can be changed if needed, for example to modify the swirling slope S. According to another embodiment, the fins54are made unitary with the control rod42, the swirl imparting element being formed by the control rod42itself.

According to a second embodiment (not illustrated), the swirl imparting element52is attached to the nozzle body34such that the fins54extend from the nozzle body34toward the control rod42. In this case, the fins54are for example made unitary with the nozzle body34and the control rod42is movable relative to the fins.

In all the above embodiments, the swirl imparting element52extends preferably in the vicinity of the outlet26, as close as possible to said outlet26.

According to an embodiment, the swirl imparting element52extends upstream of the sealing part44of the control rod42. In this case, the swirl imparting element52extends in the nozzle chamber28, for example in the regular cylindrical portion of said chamber. In this case, the swirl imparting element52extends in a part having a radial dimension, i.e. a diameter in the case of a circular cross-section of the nozzle chamber28, larger than the radial dimension of the outlet26.

According to another embodiment, the swirl imparting element52extends downstream of the sealing part44of the control rod42. In this case, the swirl imparting element is placed in a tubular portion64forming the outlet26and extending downstream of the valve seat45. In this case, the swirl imparting element52extends in a part having a radial dimension which is substantially equal to the radial dimension of the outlet26and is in the immediate vicinity of the outlet26. In the case where the swirl imparting element52is attached to the control rod42, the control rod42can comprise a part extending downstream of the sealing part44in the tubular portion64.

According to a particular embodiment shown inFIG. 5, the fins54have a radial dimension, i.e. a cross-section in a radial plane, substantially equal to the radial distance separating the control rod42from the wall of the nozzle chamber28or from the wall of the central bore62. In this case, the fins54extend radially across the whole injection flow.

According to another embodiment shown inFIG. 6, the fins54have a radial dimension which is inferior to the radial distance separating the control rod42from the wall of the nozzle chamber28or from the wall of the central bore62. In this case, the fins extend radially across a part of the injection flow only.

In a variant, the radial dimension of the fins is variable between the upstream end56and the downstream end58such that the fins extend radially more or less across the injection flow.

The above described embodiments can be applied in combination with the previous described embodiments, i.e. when the fins are attached to the control rod42or when they are attached to the nozzle body34and/or when the swirl imparting element52extends upstream or downstream of the sealing part44.

Apart from the swirl imparting element52, the forming station4described above is only a non-limitative example and modifications could be brought. For example, the injection could not comprise a stretch rod50or a movable part35and/or the actuation means could be different from the ones described above.

The method for simultaneous simultaneously forming and filling a container from the preform2using a forming station described above will now be described.

A heated preform2is placed in the mold16, which is then closed. By heated, it is meant that the preform2is in a malleable state. If such a malleable state can be achieved without heating the preform2, then such a heating is not required.

The outlet26of the injection nozzle18is then placed in fluidic communication with the inner opening14of the preform2for example by moving the movable part35to place it in fluid tight contact with the neck12of the preform2.

During this step, the closing valve41is in closed position such that liquid cannot flow through the outlet26. The pressurized liquid source20is arranged to fill the nozzle chamber28with pressurized liquid such that when the closing valve41is moved in opened position by moving the sealing part44away from the valve seat45pressurized liquid flows into the preform2through the outlet26.

When the forming station4comprises a stretch rod50, the method comprises a step of axial stretching of the preform2using the stretch rod50. This step can occur prior moving the closing valve41in the opened position or at the same time. The stretch rod50is moved in translation along the preform axis A until it contacts the closed extreme part10of the preform2and then moved further such that the preform is expanded, or stretched, in the preform axis direction until it contacts the bottom of the molding cavity22.

During this step or once this step is completed, the closing valve41is opened such that pressurized liquid is injected in the preform through the outlet26. The liquid flows into the preform thanks to the difference of pressure between the nozzle chamber28, which contains pressurized liquid at a pressure greater than the atmospheric pressure, and the inner volume of the preform, which is, before the closing valve41is opened, at atmospheric pressure. Since the preform2and the injection nozzle18are in liquid tight contact, the pressure difference which is established when the closing valve41is opened causes the liquid to flow into the preform2.

When flowing towards the outlet26, the pressurized liquid flows through the fins54of the swirl imparting element52, which therefore modifies the flow of liquid thanks to the swirling slope S of the fins54. Before flowing through the swirl imparting element52, the liquid flows in the nozzle chamber28along the injection axis A. The swirl imparting element52further causes the liquid to rotate around the injection axis A, as shown by arrows ofFIG. 2. Consequently, the liquid adopts a swirl flow comprising a movement along the injection axis and a rotation around the injection axis A. The pressurized liquid therefore gains a centrifugal force due to the rotation around the injection axis A. The swirl imparting element52is arranged to make sure that the liquid is swirling around the injection axis A when it fills the preform.

Consequently, when the pressurized liquid enters the inner volume of the preform2, it imparts a centrifugal force against the wall15of the preform2which causes the preform2to expand in radial planes as well as in the axial direction. The greater the centrifugal force of the liquid is, the greater the radial expansion of the preform2is. The centrifugal force can be adjusted by modifying the swirling slope S, i.e. by adjusting angle α and depends on the viscosity and pressure of the injected liquid. Consequently, angle α can be chosen depending on the pressurized liquid to be injected to have a sufficient centrifugal force while ensuring a proper flow of the liquid in the preform2. Similarly, the choice of having fins54which extend across the whole injection flow and across a part of it only is made depending on the liquid to be injected, as explained previously.

The preform during this forming and filling step therefore expands both in the axial direction and in radial planes as shown inFIG. 2until the wall15contacts the wall of the molding cavity and is pressed against it Thanks to the centrifugal force applied by the liquid, the preform is evenly applied against the wall of the molding cavity and the details to be imparted on the container, such as ridges, ribs, or other details, are well defined.

Consequently, the obtained filled container is well shaped and its bi-orientation ratio is satisfactory.

The container is not formed from bottom to top as it is usually the case in conventional hydroforming methods because the liquid impacts the wall of the preform along a major part of the height of the preform substantially simultaneously thanks to the swirl flow of the liquid. According to an embodiment, the liquid impacts simultaneously the wall of the preform along the whole height of the preform. The height of the preform is defined as the dimension of the preform along the preform axis A.

When the forming and filling of the container is completed, the sealing part44is moved against the valve seat45to close the closing valve41and the formed and filled container is retrieved from the mold16. The method can then take place again with a new preform2.