Apparatus for conveying a dose of polymeric material to a moulding apparatus

Abstract

Apparatus (3) for conveying a dose of polymeric material to a moulding apparatus (5), comprising: a plurality of conveying elements (301) movable along an annular path (P) for conveying doses (4) towards respective receiving parts of a mould (500) of the moulding apparatus (5); each conveying element (301) having a pusher (304) movable between a retracted position, in which the dose (4) is retained in the conveying element (301), and an extended position, in which the dose (4) is transferred to a respective receiving part of a mould (500); each conveying element (301) having a feed duct (305), in fluid communication with the pusher (304); said conveying apparatus also comprising a pneumatic circuit (7), having a pressurised fluid feed source (701) and a vacuum source (702), said sources (701, 702) being in fluid communication with the feed duct (305) of each conveying element (301) to cause alternatively the extended and retracted positions of the pusher (304); said pneumatic circuit (7) comprising a first set of channels (101) and a second set of channels (102), each channel (101, 102) being in fluid communication with the vacuum and / or pressure source (702, 701) and with at least one feed duct (305) of a respective conveying element (301).

Description

[0001] APPARATUS FOR CONVEYING A DOSE OF POLYMERIC MATERIAL TO A MOULDING APPARATUS DESCRIPTION

[0002] This invention relates to an apparatus for conveying a dose of polymeric material to a moulding apparatus.

[0003] In more detail, this invention can be included in systems for making concave objects, in particular for example caps, provided with compression moulding apparatuses.

[0004] The prior art systems for making concave objects comprise an extruder for supplying a continuous extrusion of polymeric material in a melted state and a moulding apparatus, typically in the form of a moulding carrousel, comprising a plurality of moulds, each of which is configured to make an object from a dose of polymeric material.

[0005] Each mould is provided with a first part and a second part which are suitable for operating in conjunction with each other to mould the object. In fact, the first mould part and the second mould part are movable relative to each other between an open position, in which the dose is rested on a receiving part of a mould, selected from the first mould part or the second mould part and a closed position, in which the object is moulded between the first mould part and the second mould part.

[0006] For example, the first mould may be a female mould part, provided with a moulding cavity, inside which a male element, or moulding punch, of the male mould part may be received, which is suitable for interacting with the female mould part thereby moulding the dose of polymeric material, previously positioned in the moulding cavity so as to obtain the concave object.

[0007] A conveying apparatus is interposed between the extruder and the moulding carrousel and is shaped like a disk rotatable around an axis of rotation. The disk supports a plurality of conveying elements which are movable along a closed path, along which it is possible to identify a pick-up position and a releasing position. In the pick-up position, each conveying element picks up a dose of polymeric material from the extruder. The dose remains adhering to the conveying element until it reaches the releasing position, in which the dose detaches from the conveying element and is released into the mould of the carrousel, making the dose fall from above towards the receiving part of a mould.

[0008] Also defined along the path of the conveying elements there is a reject position, positioned downstream of the releasing position, in which it is possible to make any doses which are not suitable for moulding and for this reason were not released into the mould fall into a reject container. Each conveying element is provided with a lower cutting edge suitable for interacting with the continuous extrusion which comes out of the extruder. More specifically, when the conveying component passes near the extruder, the cutting edge separates from the continuous extrusion a dosed quantity of polymeric material in a melted state, also called a dose. The dose is then picked up by the conveying component and conveyed by the latter until it is near the moulding carrousel. At this point, the conveying element releases the dose into the receiving part of a mould, so that it can be shaped between a male mould part and a female mould part to mould the object.

[0009] Each conveying element also comprises a pusher, which can be moved between a retracted configuration and an extended configuration. The pusher is normally connected to a suction source which keeps it in the retracted configuration, in which the dose, if present, remains adhering to the conveying element. When the conveying element reaches the releasing position, the pusher is put in fluid communication with a compressed air source and a flow of compressed air shifts the pusher into the extended configuration, so that the dose detaches from the conveying element and is released into a mould part below.

[0010] If it is necessary to reject a dose, in the releasing position the pusher remains in the back configuration, so that the dose to be rejected is notmade to fall into the mould, but remains adhering to the conveying element. When the reject position is reached, the pusher is shifted into the extended configuration, so that the dose to be rejected detaches from the conveying element and falls into the reject container below.

[0011] The pneumatic circuit which connects the compressed air source and the vacuum source to the individual pushers, comprising a set of passage ducts, alternating with each other in the rotation path of the conveying elements, to sequentially put in fluid communication the respective pushers.

[0012] In particular, the pushers are pneumatic pistons provided with respective connecting channels to the vacuum / compressed air sources which are obtained inside the carrousel. During the rotation, the ends of the above-mentioned channels each time are fluidly connected with the above-mentioned ducts made in a fixed central portion of the carrousel. The length of each duct, which is made in the shape of a curved slot, therefore determines the time for which each pusher remains in the retracted or extended condition.

[0013] Conveying apparatuses of the type described above, although capable of effectively feeding the dose into the respective mould, can however be improved on as regards various aspects and have important production limits.

[0014] As mentioned above, if it is necessary to reject a dose, for example due to a mould malfunction or due to an incorrect action picking up from the extruder, the pusher remains in the back configuration even if the respective connecting channel is put in fluid communication with the duct intended for feeding the compressed air. In fact, in this case, a solenoid valve is activated on the pneumatic circuit to avoid the passage of compressed air but to keep a vacuum condition even in the slot intended for feeding the dose.Therefore, even in the releasing position the pusher is retained in the retracted position, retaining the dose for a subsequent release in the reject step.

[0015] Even regarding the duct (slot) corresponding to the reject step, the solenoid valve causes the passage of compressed air or of vacuum depending whether or not the dose must be rejected, therefore corresponding to the need to extract the pusher or keep it retracted.

[0016] In this context, the ducts corresponding to the dose feed position and to the reject position are intended to receive only one channel at a time so as to put in fluid communication one pusher at a time with the respective compressed air / vacuum source.

[0017] In this way, it is in fact possible to determine for each pusher, if it is necessary to extract the pusher to feed the dose or to retract the pusher to retain the dose.

[0018] For that purpose, the above-mentioned ducts, which are made in the shape of curved slots, must be particularly short, so as to only receive one channel at a time, therefore putting only one respective pusher at a time in fluid communication. That need is due to the fact that, for two adjacent pushers, different dose releasing or retaining conditions may be set. The coexistence inside the same slot of two channels belonging to two adjacent pushers, would in fact make it impossible to give them different dose releasing or retaining conditions corresponding to the distribution of compressed air or vacuum in the slot.

[0019] However, as specified above the length of the curved slot for releasing the dose corresponds to a pusher extraction time. In this context, obtaining a particularly short slot means that the extraction time is also short and for this reason often subject to errors in the positioning of the dose itself.

[0020] In fact it should be noticed that to guarantee precise positioning of the dose on the cavity of the mould, the pusher must be kept in the extraction step for as long as possible, during the entire time for which the carrouselcarries the transfer element at the mould which is also mounted on a carrousel rotating the opposite way.

[0021] However, in this context, the need to keep a slot short results in an extraction time that is sometimes too short and subject to errors in the positioning of the dose on the mould.

[0022] One aim of the invention is therefore to improve the effectiveness of the pusher in the extraction step, by guaranteeing for as long a time as possible the pusher in the extraction step during releasing of the dose on the mould.

[0023] Another aim of this invention is to improve the management of the individual pushers, switching them independently in the dose releasing or retaining step and depending on whether or not the dose must be rejected. A further aim is to increase the speed of each individual pusher, both in the extraction step and in the pull back step, therefore increasing the production speed of the apparatuses for making objects made of polymeric material by compression moulding.

[0024] In a first aspect of the invention, a conveying apparatus is provided for conveying a dose of polymeric material to a moulding apparatus, comprising a plurality of conveying elements movable along an annular path for conveying doses towards respective receiving parts of a mould of the moulding apparatus. Each conveying element has a pusher movable between a retracted position, in which the dose is retained in the conveying element, and an extended position, in which the dose is transferred to a respective receiving part of a mould. Advantageously, each conveying element has a feed duct, in fluid communication with the pusher. In this way, a pneumatic circuit, having a pressurised fluid feed source and a vacuum source, puts the sources in fluid communication with the feed duct of each conveying element to cause alternatively the extended and retracted positions of the pusher.

[0025] Advantageously, the pneumatic circuit comprises a first set of channels and a second set of channels, wherein each channel is in fluidcommunication with the vacuum and / or pressure source and with at least one feed duct of a respective conveying element.

[0026] The invention can be better understood and implemented with reference to the accompanying drawings, which illustrate several example, non-limiting embodiments of it, in which:

[0027] - Figure 1 shows a schematic top view, of a portion of a machine for making objects by compression moulding, which comprises an extruder, an apparatus for transferring a dose according to this invention and a moulding apparatus;

[0028] - Figure 2 is a perspective bottom view of a part of the apparatus according to this invention, with some parts cut away to better illustrate others;

[0029] - Figure 3a is a perspective top view of a part of the apparatus according to this invention, with some parts cut away to better illustrate others;

[0030] - Figure 3b shows the apparatus of Figure 3a with a part in cross-section to better illustrate a construction detail of the apparatus;

[0031] - Figure 4 is a top plan view of a part of the apparatus according to this invention;

[0032] - Figures 5a - 5c show views of a conveying element of the apparatus shown in the preceding figures, in cross-section and in respective operating conditions;

[0033] - Figure 6 shows a pneumatic supply diagram of the conveying elements of the apparatus according to this invention; and

[0034] - Figures 7a - 7h show schematic and top plan views of the apparatus according to the invention in different operating steps in which two conveying elements for respective doses are highlighted and schematically illustrated.

[0035] With reference to the figures described above, the number 1 is used to indicate in its entirety a machine for making objects by compression moulding a polymeric material. The objects which the machine 1 allows to be obtained may preferably be concave objects such as containers, capsfor containers, preforms of containers, capsules for coffee, or even other types of objects.

[0036] It should be noticed that elements common to the different embodiments will be indicated with the same reference numbers.

[0037] The machine 1, schematically shown in Figure 1, comprises an extruder device 2, suitable for supplying a continuous extrusion of polymeric material. In the example shown, the polymeric material comes out of the extruder device 2 in an outfeed direction that is substantially vertical, from the bottom upwards, but other outfeed directions may in any case be covered by this invention.

[0038] For example, the polymeric material could come out of the extruder device 2 in an outfeed direction that is inclined relative to the vertical.

[0039] The extruder device 2 may be shaped to supply a continuous extrusion having a single-layer structure, that is to say, made with a single polymeric material, or alternatively to supply a multi-layer extrusion, that is to say, comprising at least two layers of polymeric materials which are different from each other.

[0040] The machine 1 also comprises a conveying apparatus 3, which includes at least one conveying element 301 for conveying a dose 4 of polymeric material. In the example shown, a plurality of conveying elements 301 is provided, only some of which were schematically shown in Figure 1.

[0041] It should be noticed that the conveying components 301 are movable along an annular path “P” which in the example shown is circular. However, this condition is not necessary, and the path “P” could be a generic closed loop trajectory, having at least one non-circular stretch. Each conveying element 301 has a concave shape, for example a “C” shape or a “U” shape, with a concavity directed towards a direction of feed “F” of the conveying elements 301. Each conveying element 301 therefore has a retaining space 302 defined inside it, suitable for retaining the dose 4.As is better illustrated in Figure 2, each conveying element 301 is provided with a cutting edge 303 which, as it passes near an outlet (not shown) of the extruder device 2, separates the dose 4 from the continuous extrusion. The cutting edge 303 of the conveying component 301 therefore acts, in this case, as a separating element for separating the dose 4 from the continuous extrusion.

[0042] The dose 4 is then received in the retaining space 302 of the conveying component 301. The concavity which defines the retaining space 302 is internally delimited by a conveying surface to which the dose 4, which is still in a melted state, can adhere thanks to its viscosity.

[0043] It should be noticed that, as schematically shown in Figures 1 and 3a to 3c, the dose 4 has a roughly spherical shape. However, other shapes are possible for the dose 4, since the dose 4 may have the shape of a parallelepiped, or be cylindrical.

[0044] The machine 1 also comprises at least one moulding apparatus 5 for compression moulding the dose 4, obtaining the desired object from it by compression moulding. In the example shown, the moulding apparatus 5 has a plurality of moulds 500 mounted in a peripheral region of a moulding carrousel 6. Figure 1 schematically shows only a portion of the moulding carrousel 6, which is rotatable in a direction of movement “M” rotating the opposite way to the direction “F”.

[0045] Each mould 500 comprises a first mould part 501 and a second part 502, aligned with each other along a moulding line which, in the example shown, is vertical.

[0046] The first mould part 501 and the second mould part 502 are movable relative to each other, thanks to an actuator device not shown, between an open position, in which the dose 4 is received on a receiving part of a mould, selected from the first mould part 501 or the second mould part 502, and a closed position, in which the object is moulded between the first mould part 501 and the second mould part 502.For example, the first mould part 501 may be a male mould part whilst the second mould part 502 may be a female mould part which, in the open position are spaced apart from each other, so that the mould 500 can receive the dose 4, conveyed by the conveying element 301.

[0047] It should also be specified that, in this text, the terms “upper” or “lower”, “above”, or “below” refer to the female mould part 502 when the female mould part 502 is, in use, mounted in the mould 500 and is directed towards the male mould part 501 and the axis “Z” is a vertical axis.

[0048] In the closed position, the female mould part 502 and the male mould part 501 are near each other, so that a moulding chamber is defined between them and in this way it is possible to mould the object into the desired shape. As is better shown in Figures 5a - 5c, the female mould part 502 has a moulding cavity 503, which extends around an axis “Z” whilst the male mould part is provided with a punch (not shown).

[0049] In the example shown in Figure 1, the female part 502 is positioned below the male part 501. The dose 4 is transferred by the conveying component 301 when the latter is vertically aligned with the female mould part 502. In this way, the dose 4 is transferred and falls into the moulding cavity 503 of the female mould part 502 below.

[0050] In this example, the female mould part 502 is therefore the receiving part, that is to say, the mould part which receives the dose 4 to be moulded. This structure of the mould 500 in which the female mould part 502 is positioned below the male mould part 501 and receives the dose 4 in the moulding cavity 503 is shown in Figures 5a to 5c.

[0051] However, it should be specified that the receiving part could even be the male mould part 501 and in that case the dose 4 would fall so that it rests on and would be transferred onto the male mould part 501, positioned below the female mould part. However, this structure of the mould 500 is not illustrated.

[0052] For the sake of simplicity, in the text below, reference will be made to the fact that the conveying apparatus 3 is configured to convey the dose 4 to areceiving part of a mould which is the female mould part 502, and in particular to transfer the dose to the moulding cavity 503 of the female mould part 502.

[0053] Each conveying element 301 , therefore, is suitable for moving along the path “P” to convey the dose 4 towards the receiving part of a mould 502. In order to transfer the dose 4 from the conveying element 301 to the receiving part of a mould 502, each conveying element 301 comprises a pusher 304, which as will be described below is movable between a retracted position, in which the dose 4 is received in the conveying element 301 , and an extended position, in which the dose 4 is transferred to the receiving part of a mould 502.

[0054] It should be noticed that, with reference to Figure 1, along the path “P” each conveying element 301 is sequentially carried to a feed station “A” for feeding the doses 4 to respective receiving parts of a mould 500 of the moulding apparatus 5, then to a reject station “B” for rejecting doses 4 not fed to the moulding apparatus 5, and then to a pick-up station “C” for picking up the doses 4 coming out of the polymeric material extruder device 2.

[0055] For that purpose, in the station “B” a compartment 800 is provided (schematically illustrated) for collecting the rejected doses 4 which is suitable for receiving the doses 4 which were not fed to the mould 500. Those doses 4 may for example be badly positioned in the retaining space 302 of the conveying element 301 or may have defects in the material which, once detected by suitable checking systems not described and illustrated, send a signal to the control logic to prevent the defective doses 4 from being fed to the moulding apparatus 5. In this case, the doses 4 considered defective are retained in the conveying element 301 even at the feed station “A” so that in contrast they can be fed directly to the subsequent reject station “B” inside the compartment 800.Therefore, the above-mentioned pusher 304 extraction step may be implemented not just to feed the dose 4 to the mould 500 but also to feed doses 4 considered to be rejected into the compartment 800.

[0056] As is better illustrated in Figure 2 and 5b, the pusher 304 acts on the dose 4 to push the dose 4 vertically downwards during a descent step, from the retracted position to the extended position. The pusher 304 is suitable for returning to the retracted position, from the extended position, in a corresponding ascent step (Figure 5c).

[0057] Figure 2 illustrates two transfer elements 301a, 301b adjacent to each other in which the respective pushers 304 are in the extended step for pushing the dose 4 (not shown in Figure 2). The pushers 304 of the other elements 301 are in contrast in a retracted step for retaining and collecting the dose 4.

[0058] In order to be able to move the transfer element 304, each conveying element 301 comprises a feed duct 305, which is in fluid communication with the transfer element 304.

[0059] For that purpose the conveying apparatus 3 comprises a pneumatic circuit 7, schematically illustrated in Figure 6, comprising a pressurised fluid feed source 701 and a vacuum or negative pressure source 702. Both sources 701, 702 are in fluid communication with the feed duct 305 of each conveying element 301.

[0060] In particular, the feed duct 305 of each conveying element 301 is suitable for being alternatively connected to the pressure source 701, for moving the pusher 304 from the retracted position to the extended position, or to the vacuum source 702, for moving the pusher 304 from the extended position to the retracted position.

[0061] In other words, the feed duct 305 is in fluid communication with the pusher 304 and is in turn in fluid communication with the sources 701 , 702.

[0062] In this way, when the pressurised fluid (typically air) is fed to the feed duct 305, the pressurised fluid is consequently fed to the pusher 304, which is pushed downwards (Figure 5b).In contrast, when the negative pressure fluid is applied to the feed duct 305, the vacuum is consequently applied to the pusher 304, which is sucked upwards (Figures 5a and 5c).

[0063] Advantageously, the pneumatic circuit 7 also comprises a first set of channels 101 and a second set of channels 102. Each channel of the first and second sets 101, 102 is configured to be put in fluid communication with the vacuum source 701 and / or the pressure source 702 and with at least one feed duct 305 of a respective conveying element 301.

[0064] For that purpose, a first group of conveying elements 301a is provided, alternating with a second group of conveying elements 301b. The two groups of conveying elements 301a, 301b may also be identified as even conveying elements 301a alternating with odd conveying elements 301b. It should be noticed that each even conveying element 301a is interposed between two odd conveying elements 301b.

[0065] The transfer apparatus 3 also comprises a conveying carrousel 307 for the dose 4 on the periphery of which the conveying elements 301a, 301b are fixed. The carrousel 307 is rotatable around an axis “X” of rotation for moving the elements 301a, 301b along the above-mentioned annular path “P”

[0066] Preferably, as is illustrated in Figures 5a to 5c, each conveying element 301 comprises a chamber 306 made in the carrousel 307 and positioned above the retaining space 302 axially aligned with the retaining space 302 along the axis “Z”.

[0067] The chamber 306 is suitable for housing the pusher 304 inside it in such a way that in the retracted position the pusher 304 is entirely axially contained in the chamber 306 and that in the extended position the pusher 304 projects from the chamber 306 and extends into the retaining space 302 for transferring the dose 4.

[0068] It should be noticed that the chamber 306 is in fluid communication with the feed duct 305, which is also made in the carrousel 307. For that purpose, the duct 305 has a first end 305a which leads to the chamber306 and a second end 305b opposite the first end 305a which leads to a respective channel 101 , 102 of the first or second set.

[0069] The pusher 304 is preferably a substantially cylindrical piston having an outer thrust surface 304a configured to engage with the dose 4 and a hollow inner surface 304b in fluid communication with the above-mentioned chamber 306.

[0070] In this way, in the pressurised fluid distribution condition, the chamber 306 and the hollow inner surface 304b of the pusher 304 are put in a pressurised condition to push the pusher itself. In contrast, in the vacuum distribution condition, the chamber 306 and the hollow inner surface 304b are put in a negative pressure condition to suck and pull back the pusher 304 inside the chamber 306 itself.

[0071] Advantageously, as will be described in more detail below, the first group of conveying elements 301a has respective feed ducts 305 in fluid communication with the first set of channels 101 whilst the second group of conveying elements 301b has respective feed ducts 305 in fluid communication with the second set of channels 102.

[0072] It should be noticed how Figure 3b and Figure 4 schematically illustrate how the feed ducts 305 extend radially from the respective conveying elements 301 placed on the periphery of the carrousel 307 towards the centre (that is to say towards the axis “X”) of the carrousel 307 itself.

[0073] In this situation, it should be noticed that the pneumatic circuit 7 comprises a distribution body 105 having a substantially cylindrical shape and mounted fixed relative to the conveying carrousel 307 and at the centre of the carrousel 307 itself.

[0074] The first and second sets of channels 101, 102 are made inside the distribution body 105 and extending along two respective circular paths concentric with the axis “X” of rotation of the carrousel 307. In this way, during the rotation of the carrousel 307 relative to the distribution body 105, the second end 305b of each feed duct 305 is sequentially put in fluid communication with the channels of the first or of the second set 101, 102.As is better illustrated in Figures 4 and 7a to 7h, each channel 101, 102 of the first and second sets has the shape of a curved slot which may have different lengths depending on the respective pneumatic branch to which it leads.

[0075] In this way, the channels of each set 101, 102 are positioned along an annular trajectory concentric with the path “P”.

[0076] Advantageously, the first set of channels 101 extends along a circular path concentric with and parallel to the second set of channels 102.

[0077] Moreover, for each set the channels 101, 102 are spaced apart from each other in such a way as to gradually put in fluid communication each duct 305, and therefore each chamber 306, with all of the curved slots of the respective set of channels 101 , 102.

[0078] Figure 3b better illustrates the arrangement of the two sets of channels 101 and 102 made in the distribution body.

[0079] As is better illustrated in the diagram in Figure 6, each set 101, 102 comprises: at least two active channels 101a, 102a for the passage of compressed air or of vacuum for moving the pusher 304 to the extended position corresponding to the dose 4 feed condition or to the retracted position corresponding to a dose 4 retaining condition; and at least two passive channels 101b, 102b for the passage of vacuum interposed between the two active channels 101a, 102a for moving the pusher 304 to the retracted position corresponding to the mentioned dose 4 retaining condition or to a dose 4 receiving condition.

[0080] The two active channels 101a, 102a are in fluid communication with the pressurised fluid feed source 701 and with the vacuum source 702.

[0081] In this case, two regulating valves 703, 704 are provided, each of which is interposed between the sources 701, 702 and a respective active channel 101a, 102a to cause in each active channel 101a, 102a the passage of compressed air or the passage of negative pressure fluid.

[0082] In other words, the regulating valves 703, 704 appropriately controlled by a control logic, determine whether to feed the respective active channelwith pressurised fluid or with the vacuum in order to move the pusher 304 to the respective extracted or retracted position.

[0083] The two active channels 101a, 102a of each set of channels 101, 102 are respectively positioned at the feed station “A” and at the reject station “B”. Therefore, the fluid regulated by the valves 703, 704 determines if the dose 4 will be fed to the mould 500 or if the dose 4 will be fed to the compartment 800 for collecting reject doses 4.

[0084] It should be noticed that two adjacent conveying elements 301a and 301b which belong to two different groups lead to the two different active channels 101a, 102a. In other words, as is schematically illustrated in Figure 4, two adjacent conveying elements 301a, 301b are gradually put in fluid communication with a respective active channel 101a, 102a in such a way that the respective pushers 304 are simultaneously and independently moved. That condition is given by the fact that the active channels 101a, 102a are configured for the passage of the second end 305b of one feed duct 305 at a time.

[0085] Advantageously, the active channel 101a, 102a placed at the feed station “A” has a curved extent long enough to keep the pusher 304 in the extended position for a longer time corresponding to the time during which the dose 4 is positioned on the receiving part 502 of a mould 500.

[0086] Therefore, during extraction the pusher 304 can use all of the time during which the respective conveying element 301 passes above the receiving part of a mould.

[0087] The passive channels 101b, 102b comprise two primary passive channels 101c, 102c, positioned downstream of the respective active channels 101a, 102a.

[0088] The primary passive channels 101c, 102c are in fluid communication with the vacuum source 702 to keep in the retracted position the pusher 304 associated with the corresponding duct 305 which is gradually put in communication with the respective primary passive channel 101c, 102c.Two secondary passive channels 101d, 102d are also provided, positioned upstream of the active channels 101a, 102a and in particular interposed between the primary passive channels 101c, 102c and the active channels 101a, 102a. The secondary passive channels 101d, 102d are also in fluid communication with the vacuum source 702 to keep in the retracted position the pusher 304 associated with the corresponding duct 305 which is gradually put in communication with the respective secondary passive channel 101 d, 102d.

[0089] It should be noticed that the primary passive channels 101c, 102c, are shorter than the other channels and are intended for a rapid pull back of the pushers 304 into the respective retracted positions. For that purpose, the pneumatic circuit 7 also comprises a regulating valve 705 associated with the primary passive channels 101c, 102c for setting a negative pressure value greater than the negative pressure in the secondary passive channels 101 d, 102d. That greater negative pressure value allows stronger suction on the pushers 304 which after releasing the dose 4 must be rapidly returned to the retracted condition.

[0090] In fact it should be noticed that a first primary passive channel 101c, 102c is positioned at a pull back zone downstream of the feed station “A” and a second primary passive channel 101c, 102c is positioned in a zone between the reject station “B” and the pick-up station “C” for the doses 4. The pneumatic circuit 7 may also comprise further channels having a curved configuration and made in the distribution body 105 which are suitable for the passage of a cooling fluid and / or a suction fluid.

[0091] Such channels, not described in detail, are more internal than the first and second sets of channels 101 , 102 and are intended for a second circuit for the passage of the fluid alternating both a cooling fluid for the parts in contact with the dose 4 and a suction fluid for favouring any further retaining systems for an object.

[0092] In accordance with the sequence schematically illustrated in Figures 7a to 7h, two adjacent conveying elements 301a 301b are shown which belongrespectively to the first and to the second group of conveying elements. In other words, the conveying element 301a of the first group represents an even conveying element 301a whilst the conveying element 301b of the second group represents an odd conveying element 302b.

[0093] During the rotation of the carrousel in the direction “F” the feed ducts 305 of each conveying element 301a, 301b are gradually put in fluid communication with the channels 101, 102 of a respective group.

[0094] In Figure 7a both of the conveying elements are placed in the feed station “A” and the feed ducts 305 are both in the respective active channels 101a, 102a. In this case the valves 703, 704 cause the feeding of pressurised fluid to extract the pusher 304 and to position the dose 4 on the mould 500. Alternatively at least one of the due active channels 101a, 102a may be fed with the vacuum to keep the dose inside the conveying element 301a, 301b.

[0095] Then, as shown in Figure 7b, the odd conveying element 301b which leads to the second set of channels 102 passes into the first primary passive channel 102c for rapidly retracting the pusher 304 whilst the even element 301a is still in fluid communication with the active channel 101a of the first set of channels 101.

[0096] Then, as is shown in Figure 7c, the odd conveying element 301b passes into the secondary passive channel 102d whilst the even element 301a accesses the inside of the first primary passive channel 101c also for rapidly retracting the pusher 304.

[0097] Then, as is shown in Figure 7d, both of the conveying elements 301a, 301b are put in fluid communication with the secondary passive channels 101d, 102d for a particularly long path corresponding to keeping the respective pushers 304 in the retracted conditions.

[0098] Then, as is shown in Figure 7e, the odd element 301b enters into the active channel 102a, intended if necessary for supplying the dose 4 into the compartment for collecting reject doses 800. In this case, if the dose 4 has already been fed to the mould 500 the active channel 102a is put influid communication with the vacuum source 702 in order to keep the pusher 304 in the retracted position. Alternatively, the active channel 102a is put in communication with the pressurised fluid source to move the pusher 304 and therefore to reject the dose 4.

[0099] Then, as is shown in Figure 7f, the even element 301a also enters the active channel 101a, intended if necessary for supplying the dose 4 into the compartment 800 for collecting the reject doses. In this situation, the odd conveying element 301b in contrast is put in communication with a second primary passive channel 102c configured to pull back the respective pusher 304 into the retracted condition as rapidly as possible. Then, as is shown in Figure 7g, the odd element 301b enters the secondary passive channel 102d whilst the even element 301b enters the primary passive channel 101 d.

[0100] It should be noticed that in this position corresponding to the dose 4 pickup station, both the even 301a and odd 301b conveying elements have the respective pusher 304 in the retracted position for receiving a new dose 4 from the extruder device 2.

[0101] Finally, as is shown in Figure 7h, both of the conveying elements 301a, 301b are in fluid communication with the respective secondary passive channels 101d, 102d for carrying a new dose towards the moulding apparatus 5.

[0102] It should be noticed that the secondary passive channels 101d, 102d upstream of the feed station “A” are also particularly long compared with the active channels 101a, 102a and compared with the primary passive channels 101c, 102c for retaining the respective pushers 304 for longer in the dose 4 receiving retracted position.

[0103] This invention solves the problems of the prior art and brings important advantages.

[0104] First of all, it should be noticed that the alternating position of the conveying elements 301a, 301 relative to the first and second sets of channels 101, 102, allows one element at a time to be positioned inside arespective active channel 101a, 102a. That, as specified above, allows autonomous and independent management of the pusher 304 of each element 301a, 301b in fluid communication with the respective active channel 101a, 102a which must be extracted to push the dose 4 or retracted to retain the dose 4.

[0105] Advantageously, it is possible to obtain an active channel 101a, 102a at the feed station “A” which is particularly long to keep the pusher 304 on the receiving part of a mould 502 for as long as possible thereby improving and making more precise the positioning of the dose 4 in the mould 500. In other words, it is possible to retain the dose 4 on the receiving part of a mould 502 for a long period, depending on the extent of the active channel 101a, 102a, and allowing improvement of the step of positioning the dose on the mould 500.

[0106] In addition, it should be noticed that the separation of the passive channels into primary 101c, 102c and secondary 101d, 102d allows optimisation of the negative pressure value to be implemented in order to retract the pusher 304. In fact, whilst in the secondary passive channels 101 d, 102d the pusher 304 must only be kept in position, in the primary passive channels 101c, 102c, it is possible to apply greater suction force to retract the pusher more rapidly.

[0107] That action speeds up the entire process also making more optimal the management of the vacuum which must only have a greater negative pressure value at the primary passive channels 101 d, 102d.

Claims

CLAIMS1. An apparatus for conveying a dose of polymeric material to a moulding apparatus, comprising:- a plurality of conveying elements (301) movable along an annular path (P) for conveying doses (4) towards respective receiving parts of a mould (500) of the moulding apparatus (5);- each conveying element (301) having a pusher (304) movable between a retracted position, in which the dose (4) is retained in the conveying element (301), and an extended position, in which the dose (4) is transferred to a respective receiving part of a mould (500);- each conveying element (301) having a feed duct (305), in fluid communication with the pusher (304);- said apparatus also comprising a pneumatic circuit (7), having a pressurised fluid feed source (701) and a vacuum source (702), said sources (701 , 702) being in fluid communication with the feed duct (305) of each conveying element (301) to cause alternatively the extended and retracted positions of the pusher (304);characterised in that said pneumatic circuit (7) comprises a first set of channels (101) and a second set of channels (102), each channel (101, 102) being in fluid communication with the vacuum and / or pressure source (702, 701) and with at least one feed duct (305) of a respective conveying element (301).

2. The apparatus according to the preceding claim, wherein said plurality of conveying elements (301) comprises a first group of conveying elements (301a) alternating with a second group of conveying elements (301b); said first group of conveying elements (301a) having respective feed ducts (305) in fluid communication with the first set of channels (101) and said second group of conveying elements (301b) having respective feed ducts (305) in fluid communication with the second set of channels (102).

3. The apparatus according to any one of the preceding claims, whereineach channel (101, 102) comprises a curved slot; said channels (101, 102) of each set being positioned along an annular trajectory.

4. The apparatus according to the preceding claim, wherein said first set of channels (101) is parallel to the second set of channels (102).

5. The apparatus according to any one of the preceding claims, wherein each set (101, 102) comprises:- at least two active channels (101a, 102a) for the passage of compressed air or of vacuum for moving the pusher (304) to the extended position corresponding to a dose (4) feed condition or to the retracted position corresponding to a dose (4) retaining condition; and- at least two passive channels (101b, 102b) for the passage of vacuum interposed between the two active channels (101a, 102a) for moving the pusher (304) to the retracted position corresponding to the mentioned dose (4) retaining condition or to a dose (4) receiving condition.

6. The apparatus according to the preceding claim, wherein the two active channels (101a, 102a) are in fluid communication with the pressurised fluid feed source (701) and the vacuum source (702); said pneumatic circuit (7) having two regulating valves (703, 704) each of which is active on said sources (701, 702) to cause in each active channel (101a, 102a) the passage of pressurised fluid or of negative pressure fluid.

7. The apparatus according to claim 5, wherein each set (101, 102) comprises two primary passive channels (101c, 102c) positioned downstream of the respective active channels (101a, 102a), and two secondary passive channels (101d, 102d), positioned upstream of the active channels (101a, 102a); said primary and secondary passive channels (101c, 101 d, 102c, 102d) being in fluid communication with the vacuum source (702).

8. The apparatus according to the preceding claim, wherein said pneumatic circuit (7) comprises a regulating valve (705) associated with the primary passive channels (101c, 102c) for setting a negative pressure value greater than the negative pressure in the secondary passivechannels (101 d, 102d).

9. The apparatus according to any one of the preceding claims, wherein it also comprises a conveying carrousel (307) for the dose (4) on which the conveying elements (301) are fixed, said carrousel (307) being rotatable around an axis (X) of rotation for moving the elements (301) along said annular path (P).

10. The apparatus according to the preceding claim, wherein said pneumatic circuit (7) also comprises a distribution body (105) mounted fixed relative to the conveying carrousel (307) and at the centre of the carrousel (307) itself and of the annular path (P); said first and second sets of channels (101, 102) being made inside the distribution body (105) and extending along two respective circular paths concentric with the axis “X” of rotation of the carrousel (307).

11. The apparatus according to the preceding claim, wherein said feed ducts (305) of the conveying elements (301) extend inside the carrousel (307) and radially relative to the annular path (P) and relative to the axis of rotation (X) of the carrousel (307) to be put in fluid communication sequentially with the channels (101, 102) of the respective sets and to define the passage of pressurised fluid and of negative pressure fluid to each conveying element (301).

12. The apparatus according to any one of the preceding claims, wherein said annular path (P) has:- a feed station (A) for feeding the doses (4) to respective receiving parts of a mould (500) of the moulding apparatus (5);- a reject station (B) for rejecting doses (4) not fed to the moulding apparatus (5); and- a pick-up station (C) for picking up the doses (4) from an extruder device (2) for polymeric material.

13. The apparatus according to the preceding claim when it depends on claim 5, wherein said active channels (101a, 102a) being respectively positioned at the feed station (A) and reject station (B).

14. The apparatus according to claim 12 when it depends on claim 7 or 8, wherein a first primary passive channel (101c, 102c) is positioned at a pull back zone downstream of the feed station (A) and a second primary passive channel (101c, 102c) is positioned in a zone between the reject station (B) and the pick-up station (C) for the doses (4).

15. The apparatus according to any one of the preceding claims, wherein each conveying element (301) is “C”- or “U”-shaped and has a retaining space (302) for retaining the dose (4), which is open in a direction of feed (F) and is suitable for picking up the dose (4) from an extruder device (2) and for housing the dose (4) in the retaining space (302) until the dose (4) is transferred to the receiving part of a mould (500).

16. The apparatus according to the preceding claim, wherein the conveying element (301) comprises a chamber (306) positioned above the retaining space (302) and axially aligned with the retaining space (302), which is suitable for housing inside it the pusher (304) in such a way that in the retracted position the pusher (304) is entirely axially contained in the chamber (306) and that in the extended position the pusher (304) projects from the chamber (306) and extends into the retaining space (302) for transferring the dose (4); said chamber (306) being in fluid communication with the feed duct (305).

17. The apparatus according to the preceding claim, wherein the pusher (304) is piston-shaped having a thrust surface (304a) configured to engage with the dose (4) and a hollow inner surface (304b) in fluid communication with said chamber (306).

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