Injection apparatus for producing hollow plastic articles, in particular bottle preforms

Abstract

An injection apparatus 100 for injecting molten plastic into a mould with the purpose of moulding one or more hollow articles, in particular bottle preforms, comprising: two injectors 1, 2 each defining a respective longitudinal axis X, X' adapted to receive the molten plastic and to inject it alternately into the mould; and conduits 3, 31, 32, 33 having an inlet opening 30 for the molten plastic, adapted to be connected to a plasticiser 102 and to guide the molten plastic from the plasticiser 102 in the direction of the two injectors 1, 2, wherein the length of the conduit 3 is smaller than the length Ltot of each of the two injectors 1, 2 along the respective longitudinal axis X, X'.

Description

[Technical field]

[0001] The present invention relates to the field of molding hollow plastic articles, such as bottle preforms.

[0002] In particular, the invention relates to an injection device capable of producing a substantially continuous flow of molten plastic, particularly adapted to inject molten plastic coming from a plasticizer, which can be produced starting from a plastic, such as PET, in the form of flakes. [Background technology]

[0003] To manufacture the bottle preforms, an apparatus is usually used which comprises an extruder and only one injector.

[0004] The forward and backward movements of the extruder screw and the injector piston are asynchronous.

[0005] In practice, the screw rotates and melts the granules, usually PET, while moving backward along its longitudinal axis to accumulate the amount of molten plastic required for continuous injection (plasticization step), while the piston moves forward to inject the molten plastic into the mold (injection step). Vice versa, the piston moves backward while the screw rotates and moves forward along its longitudinal axis to deliver the molten plastic produced in the plasticization step (transport step), so that the injector is filled with the molten plastic (injection step).

[0006] Thus, the flow of molten plastic produced by the extruder is discontinuous.

[0007] This is a standard process carried out when the raw material that has to be melted by the extruder is in the form of pellets or particulate matter, and particularly when the raw material is virgin PET, or in the case of PET that is recycled recast.

[0008] There is an increasing demand to use materials in the form of flakes obtained by crushing preforms and bottles without melting them.

[0009] To produce a preform starting from flake PET requires a plasticizer with an extruder designed to operate differently than the extruders described above.

[0010] Unlike pelleted PET, flake PET may require a special plasticization process due to its lower apparent density, where the screw does not advance / retreat as described above, but operates in a manner referred to as pure extruding: essentially, the screw rotates at a constant speed without advancing / retreating along its longitudinal axis.

[0011] This results in a flow of molten plastic exiting the plasticizer which is substantially continuous and constant, rather than discontinuous as in the processes described above.

[0012] Therefore, the continuous flow from the extruder necessitates the need for two injectors.

[0013] Specifically, downstream of the extruder, two injectors alternately receive the molten plastic from the extruder. More specifically, the apparatus is designed such that while the first injector injects the molten plastic into the mold, the second injector receives the molten plastic from the extruder, and vice versa.

[0014] The downside to this process is that the molten plastic degrades, specifically PET, resulting in the formation of undesirable volatile compounds such as acetaldehyde and benzene.

[0015] Trying to avoid degradation of the molten plastic is not an easy task, especially when carrying out a preform manufacturing process starting from PET in flake form: at present, it is not possible with equipment for manufacturing preforms starting from PET in flake form to avoid degradation of the molten PET or in any case at least to minimize it to a satisfactory extent.

[0016] There is therefore a need for an apparatus for producing bottle preforms, in particular starting from PET in flake form, which makes it possible to reduce the degradation of the molten PET. Summary of the Invention [Problem to be solved by the invention]

[0017] The object of the present invention is to make an injection device for producing hollow articles, such as for example bottle preforms, starting from plastic that becomes melted, in particular in the form of flakes, which makes it possible to reduce the degradation of the molten plastic, and in particular the molten PET. [Means for solving the problem]

[0018] The invention achieves at least this objective, and others which will become apparent in the light of the present description, by means of an injection device for injecting molten plastic into a mould, in particular for the purpose of moulding one or more hollow articles, in particular bottle preforms, The injection unit is - two injectors, each defining a respective longitudinal axis, adapted to receive molten plastic and to alternately inject the molten plastic into the mold; - a conduit (or a tubing or conduit system) having an inlet opening for the molten plastic, adapted to be connected to the plasticizer and to guide the molten plastic from the plasticizer towards or to the two injectors; Equipped with Here, the length of the conduit is less than the length of each of the two extruders along their respective longitudinal axes.

[0019] The invention further relates to a forming device, in particular according to claim 20.

[0020] Advantageously, the injection device according to the invention makes it possible to avoid or minimize degradation of the molten plastic, and in particular of the molten PET.

[0021] For this purpose, the length of the conduits mentioned above is carefully selected.

[0022] Additional features are identified to further optimize minimization of degradation of the molten plastic.

[0023] The inventors have discovered that the length of the conduit which directs the molten plastic from the plasticizer to the injector significantly affects degradation of the molten plastic.

[0024] In particular, the inventors have discovered that excessively long conduits increase the stay time of the molten plastic at high temperatures, thereby causing degradation of the molten plastic.

[0025] On the other hand, by selecting the length of the conduit to be less than the length of each injector, it is possible to reduce the residence time of the molten plastic at high temperatures, thereby minimizing degradation of the molten plastic.

[0026] Preferably, in all embodiments, the above-mentioned conduit is the only conduit adapted to guide molten plastic from the plasticizing device towards or to the two injectors, i.e. no other conduits are provided for this purpose.

[0027] Further features and advantages of the present invention will become more apparent in the light of the detailed description of illustrative but non-exclusive embodiments.

[0028] The dependent claims describe particular embodiments of the invention.

[0029] In the description of the invention, reference is made to the accompanying drawings, which are provided as non-limiting examples. [Brief description of the drawings]

[0030] [Figure 1] FIG. 1 is a perspective view showing an injection device according to the present invention. [Diagram 2] FIG. 2 is a side view showing the injection device according to FIG. [Diagram 3] FIG. 2 is a side view showing some components of the injection device of FIG. 1. [Figure 4] FIG. 4 is a top view showing the components of FIG. 3. [Diagram 5] FIG. 5 is a cross-sectional view taken along the line AA in FIG. [Figure 6] 4 is a perspective cross-sectional view of a portion of the components of FIG. 3 in two intersecting planes. FIG. [Figure 7] FIG. 7 is a perspective cross-sectional view showing FIG. 6. [Figure 8] FIG. 4 is a side view showing some of the components of FIG. 3. [Figure 9] FIG. 9 is a cross-sectional view taken along the line BB in FIG. [Figure 10] 1 is a side view of a molding apparatus according to the invention, in which the plasticizing device is diagrammatically shown; FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] The same elements or components have the same reference numbers.

[0032] With reference to the figures, an exemplary embodiment of an injection device 100 or injection machine according to the invention is described. In particular, the injection device 100 is for molding hollow articles, and in particular preforms, more particularly bottle preforms.

[0033] In practice, the injection device 100 is adapted to inject molten plastic into a mold (not shown) of one or more hollow articles, such as bottle preforms, which are equipped with a number of molding cavities, each for a respective hollow article, for example one for a respective preform.

[0034] The injection device 100 is suitable for injecting molten plastic (or molten polymer) produced by plasticization of a polymeric material, such as, for example, PET (polyethylene terephthalate), in particular in the form of flakes.

[0035] In all embodiments, the injection device 100 comprises: - two injectors 1, 2 each defining a respective longitudinal axis X, X' adapted to receive molten plastic and to inject the molten plastic alternately between each other into a mould (i.e. into the same mould), in particular the injectors 1, 2 being connected to a pipe 5 (fig. 6) or a conduit or conduit system serving to guide the molten plastic injected by the injectors 1, 2 in the direction of the mould, and in particular in the direction of the same mould; a conduit 3 or a tubing system or conduit system having an inlet opening 30 (FIGS. 7, 8) for the molten plastic, adapted to be connected to the plasticizer 102 and to guide it from the plasticizer 102 towards or possibly up to the two injectors 1, 2; Equipped with Here, the length of said conduit 3 is smaller than the length Ltot of each of the two injectors 1, 2 along their respective longitudinal axes X, X', and in particular smaller than their total length.

[0036] The conduit 3 preferably has two outlet openings 37, 38 (FIG. 9) which are separate from each other and also from the inlet opening 30. In particular, the conduit 3 preferably has only one inlet opening 30 and only two outlet openings 37, 38.

[0037] In particular, the conduit 3 is adapted to lead from the plasticizer 102 into the two injectors 1,2.

[0038] In particular, the "length" of the conduit 3 is understood to mean the length of the path occupied by the molten plastic as it traverses the conduit 3 from the beginning to the end of the conduit 3, and in particular from the inlet opening 30 to the two outlet openings 37, 38.

[0039] In particular, the inlet opening 30 is adapted to be connected to a plasticizer 102 .

[0040] An end portion 39 of the conduit 3 is provided with the inlet opening 30 described above.

[0041] The conduits 3 may, for example, comprise curved extensions and / or extensions which are inclined relative to one another and / or branching sections, and in particular bifurcation sections.

[0042] In particular, the conduit 3 preferably comprises, and preferably consists of, a first extension 31 (Figures 5, 6, 9) provided with said inlet opening 30, and two branches 32, 33 each adapted to guide the molten plastic towards a respective injector 1, 2. Each branch 32, 33 is provided with a respective outlet opening 37, 38 of the conduit 3.

[0043] The length of the conduit 3 includes the length of the first extension 31 and the length of each of the two branches 32, 33, and in particular, the length of the conduit 3 is preferably equal to the sum of the length of the first extension 31 and the length of each of the two branches 32, 33.

[0044] The above-mentioned first extension 31 preferably comprises an extension 311 which is substantially horizontal or in any case parallel to the support plane of the injection device 100 .

[0045] The extension 311 preferably has the inlet opening 30 described above.

[0046] The above-mentioned first extension 31 preferably comprises two extensions 311, 312 (or sub-extensions or sub-portions) in a cross-sectional relationship, for example at right angles to each other. The first extension 31 can for example have a substantially L-shaped shape. The two extensions 311, 312 are joined to each other by a connecting extension 313. In particular, the connecting extension 313 is substantially a bent tube.

[0047] The portion of the conduit 3 is preferably bounded by an element, for example a T- or Y-shaped tube, comprising said two branches 32, 33. More particularly, said T- or Y-shaped element comprises a part of the first extension 31 of the conduit 3, and in particular a part of extension 312.

[0048] Each of the injection machines 1, 2 comprises a body 11, 21 (FIGS. 1, 3) adapted to receive molten plastic, a piston 12, 22 adapted to slide in the body 11, 12, and actuation means 14, 24 adapted to move the piston 12, 22. In particular, the body 11, 21, the piston 12, 22 and the actuation means 14, 24 are traversed by the same longitudinal axis X, X'.

[0049] Each injector 1,2, and in particular each body 11,21, is equipped with a respective opening through which molten plastic can pass as it enters and leaves the injector 1,2.

[0050] The molten plastic is received in particular in a space bounded by the body 11,21 and the piston 12,22 of each injector 1,2.

[0051] The length Ltot of each injection machine 1, 2 includes the length Lcm of the body 11, 21 and the length Lhc of the actuating means 14, 24 (also measured along the longitudinal axis X, X'). Preferably, the actuating means 14, 24 comprise or consist of an actuating cylinder, preferably a hydraulic cylinder.

[0052] In particular, each injector 1, 2 has a first axial end 19' (FIG. 3) and a second axial end 19". The first axial end 19' in particular defines the boundary of an opening of said body 11, 12 through which molten plastic can pass when entering and leaving said body 11, 12. The second axial end 19" is preferably an end of said actuation means 14, 24 and in particular an end distal from the opening of the body 11, 12. The length Ltot of each injector 1, 2 is in particular the distance from the first axial end 19' to the second axial end 19", along the respective longitudinal axis X, X'.

[0053] The actuation means 14,24 are preferably connected to the bodies 11,21 by connecting bodies 13,23 extending between the bodies 11,21 and the actuation means 14,24.

[0054] In this case, the length Ltot of each injection machine 1,2 comprises the length Lcm of the body 11,21, the length Lmb (along the longitudinal axis X,X') of the connecting body 13,23 and the length Lhc of the actuation means 14,24.

[0055] Valves 15,25, in particular proportional valves, may be connected to the actuation means 14,24.

[0056] The above length of each injector 1,2 preferably does not include the length of the valves 15,25.

[0057] Preferably, but not exclusively, the two injectors 1, 2 are parallel to each other, in particular their longitudinal axes are parallel to each other. Alternatively, the two injectors 1, 2 may be in a cross relationship with each other or may be aligned with each other.

[0058] In particular, the two injectors 1, 2 have an equal length Ltot.

[0059] The two injectors 1, 2 are preferably identical to each other.

[0060] Preferably, the length Ltot of each injection machine 1, 2 is between 2500 mm and 3300 mm; the length Lcm of each body 11, 21 is between 700 mm and 1200 mm; the length Lhc of the actuating means 14, 24 is between 800 mm and 1300 mm; and / or the length Lmb of the connecting body 13, 23 is between 600 mm and 1100 mm.

[0061] Preferably, but not exclusively, the injection device 100 has one or more of the following features (and combinations of these features): - the length of the conduit 3 is at least 1.5 times smaller than said length Ltot, preferably 1.6 to 2.2 times smaller; - the length of the conduit 3 is smaller than the length L cm of the bodies 11, 12 along the longitudinal axis X, X' of the injection machines 1, 2; - the internal volume of the conduit 3 is smaller than, and preferably equal to or less than half, the maximum internal volume capable of receiving the molten plastic of each injection mould 1, 2, in particular the internal volume of the conduit 3 being the total volume capable of receiving the molten plastic and the maximum internal volume of the injectors 1, 2 being the volume bounded by the bodies 11, 12 and the pistons 12, 22 in their fully retracted position (distal to the openings of the injectors 1, 2); - the ratio of length to internal diameter of said conduit 3 is between 25 and 50, in particular the internal diameter may be constant or may vary along the conduit 3, in the latter case the average internal diameter being considered for the abovementioned length / internal diameter ratio; - the plasticizing device 102, and in particular the end portion 39 of the conduit 3 adapted to be connected to the inlet opening 30, is arranged in the space between the orthogonal projections P, Q of the axial ends 19', 19" (Figure 3) of each of the injectors 1, 2, in a horizontal plane H parallel to the support plane of the injection device 100; the end portion 39 (more specifically, the inlet opening 30) is at a distance (along the horizontal plane H) from said orthogonal projection P of the end portion 19', said distance being smaller than Ltot x cosα, where α is the angle formed by the longitudinal axis X, X' and the horizontal plane H, and preferably said distance being smaller than Lcm x cosα.

[0062] Each of the above mentioned features makes it possible to improve the optimization of the volume that the molten plastic must traverse to reach the injectors 1, 2, and in particular to significantly reduce this volume.

[0063] In any case (in all embodiments), the inner diameter of the conduit 3 is preferably between 30 mm and 50 mm, in particular the inner diameter of the conduit 3 is selected within this range in order to reduce to a minimum undesirable effects on the molten plastic, including the formation of undesirable materials, e.g. due to excessive shear stresses.

[0064] The end portion 39 of the conduit 3, and in particular the inlet opening 30 adapted to be connected to the plasticizing device 102, is preferably arranged in a space below, and in particular below and including, the two injectors 1, 2, or above, and in particular above and including, the two injectors 1, 2.

[0065] The end portion 39 preferably includes a flange for connection to a plasticizer 102 .

[0066] The injection unit 100 is configured to receive molten plastic by two injection units 1, 2 and alternately inject the molten plastic into a mould.

[0067] In particular, the apparatus 100 is configured such that when one of the injectors, injector 1, receives molten plastic (i.e., is filled with molten plastic), the other injector, injector 2, injects molten plastic (and therefore becomes empty).

[0068] In particular, the device 100 comprises one or more valves 41, 42 (preferably spool valves) for allowing alternate input of molten plastic into one of the injectors 1 and injection of molten plastic out of the other injector 2. Preferably, the injection device 100 comprises two valves 41, 42, in particular one valve 41, 42 for each injector 1, 2.

[0069] The conduit 3 preferably extends from an inlet opening 30 for the molten plastic to said two valves 41, 42.

[0070] The two branches 32, 33 of the conduit 3 are preferably in particular fixedly connected to the respective valves 41, 42, in particular fixedly connected to the bodies 411, 421 of the respective valves 41, 42.

[0071] Each valve 41, 42 is adapted to allow or prevent molten plastic from entering the respective injector 1, 2 depending on its position or configuration.

[0072] More specifically, when in a first position, each valve 41, 42 allows molten plastic to pass from the conduit 3 to the respective injector 1, 2 (injection step) and prevents molten plastic from passing from the respective injector 1, 2 toward the mold, and when in a second position, each valve 41, 42 allows molten plastic to pass from the respective injector 1, 2 toward the mold (injection step) and prevents molten plastic from passing from the conduit 3 to the respective injector 1, 2.

[0073] 6, in particular, the injection device 100 is configured such that the molten plastic coming from the plasticizer 102 is introduced into the conduit 3, and in particular into the first extension 31 and further into the branches 32, 33. Alternately, the valve 42 allows the passage of the molten plastic from the conduit 3 to the injector 2 and prevents the passage of the molten plastic from the respective injector 2 in the direction of the mould, whereas the other valve 41 allows the passage of the molten plastic from the injector 1 in the direction of the mould and prevents the passage of the molten plastic from the conduit 3 to the injector 1.

[0074] In particular, the device 100 is configured such that when one of the two valves 41, 42 is in a first position, the other valve 41, 42 will be in a second position.

[0075] In particular, the jetting device 100 is configured to control the valves 41 and 42 such that when the valve 41 is in its first position, the valve 42 will be in its second position, and vice versa. Indeed, the jetting device 100 is configured to pass the valve 41 from the first position to the second position and vice versa, and to pass the valve 42 from the first position to the second position and vice versa.

[0076] FIG. 6 shows, by way of non-limiting example, the moment when injection machine 1 has completed the injection step while injection machine 2 is just about to start the injection step.

[0077] Each valve 41, 42 is preferably a two-position valve.

[0078] Each valve 41, 42 is preferably a three-way valve, in particular a three-way two-position valve.

[0079] Each valve 41, 42 is preferably configured to allow an amount of molten plastic to be received by each of the valves 41, 42 (or more specifically, to pass through) that is less than, and in particular significantly less than, the amount that can be received within the conduit 3.

[0080] As an alternative to two valves 41, 42, only one valve may be provided which can allow the input of one injection machine and the injection of the other and vice versa.

[0081] In a variant not shown, the number of valves for controlling the flow of molten plastic towards the injectors 1, 2 may be more than two, for example three.

[0082] For actuating each valve 41, 42, and in particular for passing each valve 41, 42 from a first position to a second position and vice versa, actuating means 413, 423 are provided for each valve 41, 42 (FIG. 1). For example, a respective actuating cylinder is provided for each valve 41, 42.

[0083] Preferably, the body 411, 421 of each valve 41, 42 is fixed to the respective injector 1, 2. In particular, the body 411, 421 of each valve 41, 42 is fixed to an end portion of the respective injector 1, 2, in which end portion there is an opening, in particular from the body 11, 21, for the inflow and outflow of the molten plastic of the respective injector 1, 2.

[0084] Inside the body 411, 412 of the valve 41, 42 there is a movable element 412, 422. The movable element 412, 422 preferably defines a conduit which, in one position of the valve 41, 42, can be in fluid communication with the conduit 3 and with the openings of the injectors 1, 2. The movable element 412, 422 further defines a conduit which, in another position of the valve 41, 42, can be in fluid communication with the openings of the injectors 1, 2 and with the tubing 5, and in particular with the respective branches 51, 52 of the tubing 5.

[0085] Each of the above mentioned actuation means 413,423 is adapted to move a respective movable element 412,422.

[0086] As mentioned above, the apparatus 100 further comprises a tube 5 or channel (Figure 6) which serves to guide the molten plastic injected by the injectors 1, 2 towards the mould, and in particular towards or into the same mould.

[0087] The tubing 5 comprises an extension 50 adapted to receive molten plastic from the injectors 1, 2. In particular, the extension 50 can receive both the molten plastic injected by injector 1 and the molten plastic injected by injector 2.

[0088] The tubing 5 further comprises two branches 51, 52 (or, more generally, one branch for each injector) or extensions, each branch 51, 52 adapted to receive molten plastic from a respective injector 1, 2, i.e. each extension 51, 52 is adapted to receive a respective flow of molten plastic from a respective injector 1, 2. In particular, each branch 51, 52 is connected to the outlet of a respective valve 41, 42.

[0089] The extension 50 is connected to two branches 51, 52. In particular, the two branches 51, 52 converge in the extension 50, i.e. a flow of molten plastic emerging from each branch 51, 52 is introduced into the extension 50. In particular, the extension 50 is fluidically downstream of the branches 51, 52.

[0090] Suitably, a valve 6 is provided along said extension 50 of the tubing 5 .

[0091] Preferably, extension 50 comprises a first extension 53 and a second extension 54 (or sub-extension), both connected to valve 6. In particular, extension 53 is upstream of valve 6 and extension 54 is downstream of valve 6. Extension 54 is essentially a nozzle.

[0092] The valve 6 is in particular adapted to allow or prevent the passage of molten plastic in the direction of the mould, depending on its position.

[0093] In a first position, the valve 6 allows the passage of molten plastic in the direction of the mold, and in a second position, it allows the exit of molten plastic from the extension section 50 (preventing the molten plastic from reaching the mold), in particular for the purpose of performing a purging operation.

[0094] The valve 6 is preferably a two-way valve, in particular a two-way two-position valve. For actuating the valve 6, actuating means 61, for example an actuating cylinder, are provided.

[0095] In particular, the valve 6 is only used for the purge step, which is specifically the step of starting up the moulding device 101 (comprising the injection device 100 and the plasticiser 102). In practice, instead of injecting the first charge of molten PET from each injector 1, 2 directly into the mould, it is preferred to discharge such material into a collection tray (not shown), in particular outside the tube 5. This is because during the heating step before the start of full operation, if the first material is present for a long time inside the plasticiser 102, it will be highly degraded. If it were to be injected into the mould, it would be filled with a highly degraded material, which would also be difficult to remove.

[0096] The injection device 100 preferably comprises a body 8, with the tubing 5 connected to the body 8, in particular to the extension 50, and more particularly to the extension 54. The body 8 is adapted to be connected to a mould.

[0097] Two cylinders, preferably two hydraulic cylinders 71, 72, are preferably provided to allow maintenance operations and special cleaning operations, for example removal of the extension 54 (or nozzle). The hydraulic cylinders 71, 72 allow the injectors 1, 2 to move backwards, i.e. the hydraulic cylinders 71, 72 allow the injectors 1, 2 to move away from the mould, and the hydraulic cylinders 71, 72 allow the injectors 1, 2 to move forwards, i.e. the hydraulic cylinders 71, 72 allow the injectors 1, 2 to move towards the mould. In particular, the two hydraulic cylinders 71, 72 comprise respective parts 711, 721 adapted to press the body 8. During normal operation (full operation) after the injection unit 100 has been moved forward towards the mould in the working position, the two hydraulic cylinders 71, 72 serve to maintain the injection unit 100 in contact with the mould, since they are adapted to exert a force sufficient to counter the separating force imparted by the injection pressure tending to separate the nozzle 54 from the mould.

[0098] The conduit 3 (in particular the extension 311) is delimited by parts 91, 92 adapted to slide relative to each other to form a telescopic system. In particular, part 91 is preferably inserted into part 92. Part 91 delimits the inlet opening 30 of the conduit 3 and is adapted to be fixed, and in particular rigidly fixed, to the plasticizer 102. During the above-mentioned retreat and advancement of the injectors 1, 2, part 92 can slide relative to part 91. In particular, this sliding can take place along an axis that is substantially horizontal or in any case parallel to the support plane of the injection device 100. The injection device 100 is preferably configured to allow a change in length of the conduit 3 by the above-mentioned optional telescopic system of up to 150 mm or 100 mm. If a telescopic system is provided, the above-mentioned length of the conduit 3 preferably refers to its maximum length when the injectors 1, 2 are in a proximal position relative to the mould (the distal position being the position when the injectors 1, 2 are moved to their furthest position from the mould by the hydraulic cylinders 71, 72, in which distal position the conduit 3 is in its maximum extended position).

[0099] The telescopic system is particularly advantageous if the plasticizer 102 is of the kind that must be particularly rigidly fixed to the ground (or in any case to the support plane of the injection device 100), i.e. if the plasticizer 102 is fixed in place. In fact, it makes it possible to feed horizontally the injection machines 1, 2 and the components rigidly fixed to the injection machines 1, 2, including the valves 41, 42, the pipes 5 and the conduits 3, except for the part 91 (which is in fact rigidly fixed to the plasticizer 102, which is preferably fixed in place).

[0100] Preferably, but not exclusively, the two injection machines 1 , 2 are inclined at an angle α of preferably 10° to 45° with respect to a horizontal plane H that is parallel to the support plane of the injection device 100 .

[0101] In particular, the two injectors 1, 2 are preferably inclined so that the end portion 19' is further below (closer to the support plane of the injection device 100) relative to the end portion 19" opposite to the end portion 19' in the axial direction, when openings for the inflow and outflow of molten plastic by the injectors 1, 2 (in particular from the bodies 11, 21) are provided.

[0102] Among the advantages associated with the inclination of the injectors 1, 2 is the optimisation of capacity: in fact, this makes it possible to reduce the horizontal volume of the injection device 100 and even to arrange at least part of the plasticisation device 102 in the space below the injectors 1, 2. The inclination of the injectors 1, 2 makes it possible to reduce the length of the conduit 3 and therefore the residence time of the molten plastic inside the conduit 3.

[0103] This feature relating to the tilt of the injectors 1,2 is therefore preferably, but not exclusively, associated with the arrangement of the end portion 39 of the conduit 3 in the space below the injectors 1,2.

[0104] The injection device 100 preferably comprises a support structure 7 adapted in particular to support the injection machines 1, 2. The injection machines 1, 2 are preferably constrained to the support structure 7 such that they slide relative to the support structure 7. For this purpose, for example, two sliding guides 73, 74 are provided.

[0105] The injection device 100 is adapted to be connected to and operate with a plasticizer 102, which is particularly configured to plasticize PET in the form of flakes. In particular, the plasticizer 102 is preferably configured to generate a substantially continuous flow of molten plastic.

[0106] The plasticizer 102 comprises an extruder. In particular, the extruder is configured to generate a substantially continuous flow of molten plastic. Preferably, for this purpose, the screw of the extruder rotates about its longitudinal axis, preferably at a substantially constant speed, and does not move along its longitudinal axis. The plasticizer 102 can comprise other components downstream of the extruder.

[0107] The conduit 3, and in particular the inlet opening 30 of the conduit 3, is connected to the last component of the plasticizer 102. Preferably, in all embodiments, the conduit 3 is the only conduit adapted to guide the molten plastic from the plasticizer 102 in the direction of the two injectors 1, 2, i.e. no other conduits are provided between the plasticizer 102 and the conduit 3.

[0108] As a non-limiting example, a pump, in particular for the molten plastic, may be provided downstream of the extruder in the plasticizer 102. Advantageously, a filter may be provided upstream of the pump and optionally the viscometer, and a purge valve may be provided downstream of the pump. Furthermore, one or more reactors may be provided upstream of the extruder for processing, and in particular for pre-processing, the PET flakes.

[0109] Preferably, as expected, the plasticizer 102 is fixed in place, in particular firmly fixed to the ground. In practice, the plasticizer 102 may have a weight and volume that makes it necessary to fix it to the ground, for example due to the above-mentioned reactor.

[0110] The present invention further relates to a molding apparatus 101 for producing one or more hollow articles, comprising an injection device 100 and a plasticization device 102 connected to a conduit 3 so as to enable molten plastic to pass through said conduit 3 from the plasticization device 102 to two injectors 1, 2.

Claims

1. 1. An injection device (100) for injecting molten plastic into a mold for the purpose of molding one or more hollow articles, in particular bottle preforms, comprising: The injection device (100) two injectors (1, 2) each defining a respective longitudinal axis (X, X') adapted to receive the molten plastic and alternately inject the molten plastic into the mold; a conduit (3, 31, 32, 33) having an inlet opening (30) for the molten plastic, adapted to be connected to a plasticizing device (102) and to guide the molten plastic from the plasticizing device (102) towards the two injectors (1, 2); Equipped with the length of the conduit (3) is less than the length (Ltot) of each of the two injectors (1, 2) along the respective longitudinal axes (X, X'); The injection device (100) has two injectors (1, 2) that are inclined relative to a horizontal plane (H) that is parallel to the support plane of the injection device (100).

2. 2. The injection device (100) according to claim 1, comprising one or more valves (41, 42) for alternately allowing the input of molten plastic into one of the injectors (1) and the injection of said molten plastic out of another injector (2).

3. 3. An injection device (100) according to claim 2, wherein the conduit (3, 31, 32, 33) extends from an inlet opening (30) for the molten plastic to the one or more valves (41, 42), preferably with a body (411, 421) of each valve (41, 42) fixed to the respective injector (1, 2).

4. 4. An injection device (100) according to any one of claims 1 to 3, comprising two valves (41, 42), one valve (41, 42) for each injection machine (1, 2), each valve (41, 42) adapted to allow or prevent the inflow of molten plastic in the respective injection machine (1, 2) depending on its position, preferably each valve (41, 42) being a three-way valve.

5. 5. The injection device (100) of claim 4, wherein each valve (41, 42) is adapted to take a first position and a second position, wherein in the first position, the passage of molten plastic from the conduit (3) to the respective injector (1, 2) is permitted and the passage of molten plastic from the respective injector (1, 2) towards the mould is prevented, and in the second position, the passage of molten plastic from the respective injector (1, 2) towards the mould is permitted and the passage of molten plastic from the conduit (3) to the respective injector (1, 2) is prevented.

6. 3. The injection device (100) according to claim 1 or 2, wherein the two injection machines (1, 2) are inclined at an angle of 10° to 45° with respect to the horizontal plane (H) which is parallel to the support plane of the injection device (100).

7. Each of the injectors (1, 2) comprises a body (11, 21) adapted to receive the molten plastic, a piston (12, 22) adapted to slide within the body (11, 21), and actuation means (14, 24) adapted to move the piston (12, 22), The length of the conduit (3) is shorter than the length (L cm) of each body (11, 12), and / or The length (Ltot) of each injector (1, 2) includes the length (Lcm) of the body (11, 21) and the length (Lhc) of the actuation means (14, 24), An injection device (100) according to claim 1 or 2.

8. Each of the injectors (1, 2) has a first axial end (19') and a second axial end (19"); the first axial end (19') defines an opening in the body (11, 21) through which the molten plastic can pass, in particular to enter or exit the body (11, 12); 8. The injection device (100) according to claim 7, wherein the length (Ltot) of each injector (1, 2) is the distance from the first axial end (19') to the second axial end (19"), and preferably the second axial end (19") is the end of the actuation means (14, 24).

9. 3. The injection device (100) according to claim 1 or 2, wherein the internal volume of the conduits (3, 31, 32, 33) is less than, preferably equal to or less than half, the maximum internal volume of each injector (1, 2) that can receive the molten plastic.

10. 3. Injection device (100) according to claim 1 or 2, wherein the ratio of the length to the inner diameter of the conduit (3, 31, 32, 33) is between 25 and 50.

11. the conduit (3) has two outlet openings (32, 33), the length of the conduit (3) is measured from the inlet opening (30) to the two outlet openings (37, 38), in particular the length of the conduit (3) corresponds to the length of the path occupied by the molten plastic as it traverses the conduit (3) from the inlet opening (30) to the two outlet openings (37, 38), An injection device (100) according to claim 1 or 2.

12. 2. An injection device (100) according to claim 1, wherein the conduit (3, 31, 32, 33) comprises a first extension (31) provided with the inlet opening (30) and two branches (32, 33), each adapted to convey the molten plastic towards a respective injector (1, 2), in particular each branch (32, 33) provided with a respective outlet opening (37, 38) of the conduit (3), and preferably each branch (32, 33) connected to a respective valve (41, 42).

13. 13. Injection device (100) according to claim 12, wherein a portion of the conduit (3) is bounded by a T- or Y-shaped element comprising the two branches (32, 33).

14. 14. Injection device (100) according to claim 12 or 13, wherein the first extension (31) of the conduit (3) comprises two extensions (311, 312) in crossing relationship with each other.

15. 3. The injection device (100) according to claim 1 or 2, wherein the inlet opening (30) of the conduit (3) adapted to be connected to the plasticizing device (102) is arranged in a space between orthogonal projections (P, Q) of the axial ends (19′, 19″) of each injector (1, 2) in a horizontal plane (H) parallel to the support plane of the injection device (100).

16. 3. The injection device (100) according to claim 1 or 2, wherein the inlet opening (30) of the conduit (3) adapted to be connected to the plasticizing device (102) is arranged in a space below, and in particular below and including, the two injectors (1, 2), or above, and in particular above and including the two injectors (1, 2).

17. a pipe (5) for conveying the molten plastic from the injectors (1, 2) toward the mold; the tubing (5) comprises an extension (50) adapted to receive the molten plastic from the injectors (1, 2); An injection device (100) according to claim 1 or 2.

18. 18. An injection device (100) according to claim 17, wherein a valve (6) is provided along the extension (50) of the tubing (5), which in a first position allows the passage of molten plastic in the direction of the mould and in a second position allows the molten plastic to exit from the extension (50), in particular for the purpose of carrying out a purging operation.

19. 3. An injection device (100) according to claim 1 or 2, wherein the conduit (3) is defined by two parts (91, 92) adapted to slide relative to each other, in particular to form a telescopic system, a first part (91) of the two parts (91, 92) defining the inlet opening (30) of the conduit (3) and adapted to be fixed to the plasticizing device (102), preferably inserted into the second part (92) of the two parts (91, 92).

20. 1. A molding device (101) for producing one or more hollow articles, comprising an injection device (100) according to claim 1 or 2, and a plasticization device (102) connected to a conduit (3) so as to allow molten plastic to pass from the plasticization device (102) to two injectors (1, 2).

21. 21. The molding device (101) according to claim 20, wherein the plasticizing device (102) is at least partially arranged in the space below the two injectors (1, 2).

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