Method for sorting incorrectly positioned preforms in a device for aligning and supporting preforms

Description

DOMAINE TECHNIQUE DE L'INVENTION

[0001] The invention relates to a device and a method for aligning preforms in a row and straightening them, the device being intended to be applied to axisymmetric preforms having a neck separated from a body by an annular support face, the device comprising a centrifuge bowl formed by: a horizontal circular plate rotating around a vertical axis; a fixed peripheral railing; at least one angular sector for straightening the preforms along which the bowl has a peripheral gap to allow the straightening of aligned preforms supported by their support face; at least one outlet sector arranged downstream of said angular straightening sector according to the direction of rotation of the plate. ARRIERE PLAN TECHNIQUE DE L'INVENTION

[0002] The device is intended to be implemented in a facility for manufacturing containers made of thermoplastic material, particularly polyethylene terephthalate (PET), by forming, particularly by blowing or stretch-blow molding, preforms. Such a facility makes it possible to produce containers in very large series at very high rates, for example, in excess of 85,000 bottles per hour.

[0003] According to a well-known technique, such containers are produced in two main stages. In a first stage, a PET preform is injection-molded or injection-compression-molded. This preform comprises a substantially tubular body which is closed at one of its axial ends, the opposite end being open by means of a neck. The neck has, from this injection-molding operation, the final shape of the container neck. Generally, the container neck has a thread or a groove.

[0004] The preform generally comprises an annular support face which projects radially outwards relative to the rest of the body and which is oriented axially towards the closed end of the body. Such a support face is for example carried by an annular support collar which extends radially in a projecting direction outwards relative to the rest of the preform and which is arranged at the base of the neck.

[0005] There are installations in which the preforms, once injected, are directly transmitted to the forming station, each preform being transported individually.

[0006] However, in many cases, preforms are manufactured by injection at one location and are blow-molded to the final container shape at a second location on a specific manufacturing facility. Such technology allows the blow-molding operation to be carried out as close as possible to the bottling site, and the injection operation can be carried out at any location. Indeed, it is relatively easy and inexpensive to transport small preforms, while transporting containers after blowing has the disadvantage of being economically unprofitable due to their very large volume.

[0007] In the case where the injection station and the forming manufacturing installation are two completely independent machines, the preforms are generally delivered in bulk. The blowing station therefore has a preform supply device which is equipped with a device for aligning the preforms in a row and for straightening them. The present invention relates to such a device.

[0008] An alignment and straightening device comprising a centrifuge bowl has already been proposed. The preforms are thrown in bulk onto a rotating plate forming the bottom of the bowl. The preforms are then projected by centrifugal force against a peripheral railing. A radial space reserved between the railing and the rotating plate allows the body of the preforms to pass through while retaining them by their collar. The preforms are thus aligned at the periphery of the bowl, their main axis having a substantially vertical orientation under the effect of gravity.

[0009] Such preforms aligned and straightened in a row will hereinafter be called "correctly positioned preforms".

[0010] The correctly positioned preforms are then driven towards a tangential outlet of the bowl under the effect of the rotational movement of the turntable.

[0011] In this type of device, some preforms are not correctly positioned when they arrive near the outlet of the bowl. These incorrectly positioned preforms may have an alignment defect and / or a straightening defect compared to the correctly positioned preforms. These may be, for example, preforms lying on the turntable or preforms nested in a correctly positioned preform. These preforms will subsequently be referred to as "incorrectly positioned preforms". To enable the incorrectly positioned preforms to be sorted from the correctly positioned preforms, the known device comprises sorting means which are arranged downstream of a straightening point for the correctly positioned preforms.

[0012] The sorting means allow the passage of correctly positioned preforms towards an outlet sector of the centrifuge bowl. A deflector protects the line of correctly positioned preforms present in the angular outlet sector from the intrusion of incorrectly positioned preforms.

[0013] These known sorting means consist of a disentangler wheel which has paddles mounted to rotate around a vertical axis. The paddles sweep a space located above the plate, in the immediate vicinity of the line of correctly positioned preforms to actively expel the incorrectly positioned preforms towards the center of the plate. The preforms thus expelled are directed to the start of the angular straightening sector so as to make a new turn of the bowl in the hope that they will be correctly positioned on their next passage at the level of the disentangler wheel.

[0014] However, when the preforms are relatively massive, for example each preform weighs at least 19 grams, and they feed the centrifuge bowl at a high flow rate, for example more than 80,000 preforms per hour, it has been found that incorrectly positioned preforms can be delayed in being ejected. This is likely to create a temporary blockage in the scrolling of correctly positioned preforms at the untangling wheel. It follows that the line of correctly positioned preforms has discontinuities at the outlet of the device.

[0015] Some correctly positioned preforms are thus isolated from the other preforms in the queue. Isolated preforms tend to swing in the axis of their movement. When the swing has too great an amplitude, this can cause the preform to jam, which then blocks the movement of the following preforms.

[0016] Additionally, when discontinuities extend too far, subsequent stations in the facility may not be properly supplied with preforms.

[0017] Furthermore, it may happen that a preform is incorrectly positioned because it is nested in a correctly positioned preform. However, the untangling wheel may allow an incorrectly positioned preform to pass through in this way. This requires additional sorting means to ensure that no preform thus positioned passes through the outlet of the centrifuge bowl. A method and a device according to the prior art are known from FR 3 035 090 A1. BREF RESUME DE L'INVENTION

[0018] The invention provides a method for sorting incorrectly aligned preforms from a line of correctly positioned preforms in a single-line alignment and preform straightening device which comprises a centrifuge bowl formed by: a horizontal circular plate rotating about a vertical axis; a fixed peripheral railing; at least one angular preform straightening sector along which the bowl has a peripheral gap to allow the straightening of aligned preforms by tilting a body of the preforms into the gap while the neck is supported above the gap; at least one angular outlet sector for correctly positioned preforms which is arranged downstream of the angular straightening sector in the direction of rotation of the plate; characterized in that the method consists of blowing at least one jet of compressed gas from the outer periphery of the centrifuge bowl towards the inside of the centrifuge bowl.

[0019] According to other characteristics of the method carried out according to the teachings of the invention: the gas jet is emitted in a direction having at least one radial component directed towards the centre of the plate, called the centripetal component, the gas jet passing over the neck of the correctly positioned preforms to expel incorrectly positioned preforms towards the centre of the plate; the gas jet is emitted in a direction having, in addition to the centripetal component, a tangential component directed in the opposite direction to the direction of rotation of the plate; the gas jet is blown from an area located near the downstream end of the straightening sector; the gas jet is blown continuously.

[0020] The invention also relates to a device for aligning in a row and straightening preforms which comprises a centrifuge bowl (20) formed by: a horizontal circular plate (24) rotating about a vertical axis (B); a fixed peripheral railing (28); at least one angular sector (20B) for straightening the preforms (12) along which the bowl (20) has a peripheral gap (34) to allow the straightening of aligned preforms (12) by tilting a body (14) of the preforms (12) into the gap (34) while the neck (16) is supported above the gap (34); at least one angular sector (20C) for exiting the correctly positioned preforms (12) which is arranged downstream of the angular straightening sector (20B) according to the direction of rotation of the plate (24); characterized in that it comprises at least one blowing device which comprises a nozzle for blowing the compressed gas jet which is mounted on a fixed support element located radially outside the bowl and a source of compressed gas which supplies the nozzle.

[0021] According to other characteristics of the alignment and straightening device produced according to the teachings of the invention: the blowing device comprises means for regulating the power of the gas jet; the regulating means comprise an adjustable shut-off element which is arranged in the nozzle to modify the gas passage section; the shut-off element is mounted so as to slide; the position of the blowing nozzle is adjustable in height relative to the support element; the nozzle comprises a pressure chamber which opens to the outside via a horizontal outlet slot which extends from an upstream wall of the pressure chamber to a free end of the shut-off element, the shut-off element being mounted so as to slide horizontally to allow the gas passage section to be modified. BREVE DESCRIPTION DES FIGURES

[0022] Other characteristics and advantages of the invention will appear during the reading of the detailed description which follows for the understanding of which reference will be made to the appended drawings in which: there figure 1 is a perspective view which schematically represents a device for aligning and straightening preforms comprising a centrifuge bowl in accordance with the teachings of the invention; figure 2 is a front view which represents a preform suitable for use with the device of the figure 1 , the axis of the preform being here oriented vertically; the figure 3 is a top view that represents the centrifuge bowl of the figure 1 ; there figure 4 is a radial sectional view of an alignment sector of the centrifuge bowl of the figure 1 which represents the peripheral railing and the rotating plate of the centrifuge bowl as well as an aligned preform; the figure 5 is a perspective view which represents a spillway of the device of the figure 1 ; there figure 6 is a top view which represents a part of the alignment sector of the centrifuge bowl, as well as the different stages of the path of a preform poured into the centrifuge bowl; figure 7 is a radial sectional view of a straightening sector of the centrifuge bowl of the figure 1 which represents the peripheral railing and the rotating plate of the centrifuge bowl as well as an aligned and straightened preform; the figure 8 is a schematic view along a radial direction which represents a preform aligned along the railing in the alignment sector of the centrifuge bowl of the figure 1 ; there figure 9 is a top view of the figure 8 ; there figure 10 is a view similar to that of the figure 8 which represents the preform of the figure 8 being straightened at the start of the centrifuge bowl straightening sector of the figure 1 ; there figure 11 is a top view of the figure 10 ; there figure 12 is a view similar to that of the figure 10 which represents the preform of the figure 10 straightened in the centrifuge bowl straightening sector of the figure 1 ; there figure 13 is a top view of the figure 12 ; there figure 14 is a top view depicting an area of ​​the centrifuge bowl of the figure 1 located straddling the straightening sector and a sorting sector and which comprises a blowing nozzle which blows a jet of compressed gas in accordance with the teachings of the invention; figure 15 is a vertical radial sectional view along section plane 15-15 of the figure 14 which represents the jet of compressed gas blown by the nozzle towards an incorrectly positioned preform; the figure 16 is a perspective view from inside the centrifuge bowl showing two blow nozzles made in accordance with the teachings of the invention; figure 17 is a horizontal sectional view along section plane 17-17 of the figure 16 which represents a chamber and an outlet slot of the blowing nozzle; the figure 18 is a vertical radial sectional view along section plane 18-18 of the figure 17 ; there figure 19 is a vertical radial sectional view along section plane 19-19 of the figure 17 . DESCRIPTION DETAILLEE DES FIGURES

[0023] In the remainder of the description, elements having an identical structure or similar functions will be designated by the same references.

[0024] In the remainder of the description, the following local orientations will be adopted, without limitation, for each preform present in the centrifuge bowl of the device as well as for the nozzle of the blowing device: radial "R" directed from the inside to the outside from the axis "B" of rotation of the rotating plate 24; tangential "T" which is orthogonal to the radial direction "R" and which extends parallel to the plane of the rotating plate 24, directed from upstream to downstream according to the direction of rotation of the rotating plate 24; vertical "V" directed parallel to the axis "B" of rotation of the rotating plate 24, from bottom to top according to the opposite direction of Earth's gravity.

[0025] We represented at the figure 1 a device 10 for aligning in a row and straightening preforms 12 intended to be part of an installation (not shown) for manufacturing containers made of thermoplastic material by forming, in particular by blowing or by stretch-blow molding, the preforms 12.

[0026] An example of a preform 12 for use with the alignment device 10 is illustrated in figure 2 . Such a preform 12 is made of thermoplastic material, here polyethylene terephthalate (PET). It is conventionally obtained by injection molding. It has a substantially axisymmetric shape around a main axis "A" represented vertically at the figure 2 .

[0027] It comprises a body 14 in the form of an elongated tube along the main axis "A" having a closed axial end and which has at its opposite end, shown at the top in the figure 2 , an axially open neck 16.

[0028] The preform 12 also includes an annular support face 18 which is axially oriented toward the closed end of the preform 12, which projects radially relative to the rest of the body 14. The support face 18 is arranged above a center "G" of gravity of the preform 12. The term "annular" means that the support face 18 goes around the preform 12 either continuously, as illustrated in figure 2 , either discontinuously (not shown).

[0029] When the support face is discontinuous, the annular face is for example formed of disjoint segments which go around the preform and which are nevertheless sufficiently close together so that the preform can be supported between two diametrically opposed supports whatever the position of the preform around its main axis.

[0030] In the example shown in the figure 2 , the base of the neck 16, at the junction with the body 14, has a collar which extends radially in projection relative to the rest of the preform 12. The lower face of the collar thus forms said support face 18.

[0031] In a variant not shown, the collar can be arranged elsewhere than at the base of the neck, for example at the level of the rim.

[0032] According to another variant not shown, the support face is for example formed by a lower face of a thread of the neck.

[0033] According to yet another variant not shown, the support face is attached to the preform, for example by means of a plug.

[0034] The outer diameter "D1" of the support face 18, in this case the collar, is thus greater than the maximum outer diameter "D2" of the body 14, located here directly under the collar. In the example shown in figure 2 , the closed end section of the body 14 here has a minimum external diameter "D3".

[0035] The neck 16 has its final shape, while the body 14 is intended to be stretched during a subsequent forming operation to form the body of the finished container.

[0036] Furthermore, the weight of the body 14 of the preforms 12 used is greater than the weight of the neck 16, including that of the flange. The center "G" of gravity of the preform 12 is therefore located under the support face 18 with reference to the figure 2 . Thus, a preform 12 supported by its support face 18 while resting on two diametrically opposed supports will naturally orient itself by gravity with the neck 16 at the top.

[0037] The example shown in the figure 2 is non-limiting. It will be understood that the alignment device 10 and the associated method are intended to be applied to any type of preform 12 having a support face 18 projecting radially relative to the rest of the body 14, and having a center of gravity axially offset towards the body relative to said support face 18.

[0038] As will be explained later, the alignment and straightening device 10 is capable of processing batches of identical preforms, the format of the preforms being capable of varying depending on the batch. As a result, different adjustments are capable of being made to the alignment and straightening device 10 during a change of preform format.

[0039] Coming back to the figure 1 , the device 10 mainly comprises a centrifuge bowl 20 as well as an output conveyor 22 for the row of correctly positioned and straightened preforms, hereinafter referred to as "correctly positioned preforms". The output conveyor 22 is intended to convey the correctly positioned preforms to distribute them one by one to individual handling means for each preform of a following processing station (not shown) of the manufacturing installation, for example a preform heating oven 12.

[0040] The centrifuge bowl 20 comprises a horizontal circular plate 24 rotating around a central vertical axis "B". The rotating plate 24 thus has a circular outer edge 25 shown in figure 4 The upper face of the rotating plate 24 vertically delimits downwards the interior volume of the centrifuge bowl 20. Thus, the plate 24 forms the bottom of the bowl 20.

[0041] The rotating plate 24 has an external diameter much greater than the dimensions of the preforms 12.

[0042] The rotating plate 24 can be rotated at a constant speed, here in a clockwise direction when viewed from above, for example by a motor (not shown) which is arranged under the rotating plate 24. The rotation speed is for example controlled so that the outer edge 25 of the rotating plate 24 moves between 2 and 3 m / s.

[0043] However, the rotational speed of the turntable 24 can be regulated according to the quantity of preforms accumulated in the output conveyor 22. This quantity of preforms can be detected by sensors (not shown) located in the output conveyor 22. In other words, if the quantity of preforms 12 in the output conveyor 22 is not sufficient to feed the next processing station, then the rotational speed of the turntable 24 can be increased. It is also possible to vary the quantity of preforms feeding the turntable 24.

[0044] The rotating plate 24 is here carried by a support table 26 which is fixed to the ground. The support table 26 has feet which are advantageously adjustable in height to allow the position of the rotating plate 24 to be adjusted.

[0045] The interior volume of the centrifuge bowl 20 is delimited radially outwards by a fixed peripheral railing 28 which is here fixed to the support table 26. This railing 28 has in particular the first function of retaining the preforms 12 projected outwards by the centrifugal force produced by the rotation of the rotating plate 24, and the second function of guiding the movement of the preforms 12 to an outlet passage 32 of the bowl 20 which is arranged in the railing 28, as can be seen in particular in FIG. figure 5 .

[0046] The preforms 12 are intended to be poured in bulk onto the rotating plate 24 via a fixed spillway 30. The spillway 30 is here arranged in the center of the rotating plate 24. The spillway 30 is designed to pour the preforms 12 in bulk, radially towards a receiving portion 28A of the railing 28. The spillway 30 is here in the form of a slide supplied with preforms 12 from above via a lifting belt (not shown). The top of the spillway 30 nevertheless has a relatively low height, for example approximately 40 cm above the plate 24.

[0047] As illustrated in the figure 3 , for the purposes of the description, the bowl will be divided into three fixed angular sectors relative to the support table 26.

[0048] A first angular sector 20A for aligning the preforms 12 extends opposite the outlet of the spillway 30. This angular alignment sector 20A includes the portion 28A for receiving the railing 28.

[0049] A second angular sector 20B for straightening the aligned preforms 12 is arranged directly downstream of the first angular alignment sector 20A. In a non-limiting manner, it extends here generally over 180°.

[0050] A third angular sector 20C for exiting the correctly positioned preforms 12 is arranged directly downstream of the second angular straightening sector 20B and directly upstream of the first angular alignment sector 20A. At the downstream end of this exit sector 20C, the exit passage 32 for the preforms 12 is open in the railing 28 to allow the correctly positioned preforms 12 to be guided towards the conveyor 22. The conveyor 22 here passes behind the receiving portion 28A of the railing 28.

[0051] The name of each of these sectors 20A, 20B, 20C provides an indication of their function. It will be understood subsequently that preforms 12 incorrectly aligned at the level of the first alignment sector 20A can nevertheless be aligned and straightened at the level of the second angular sector 20B according to the circumstances.

[0052] Over the entire periphery of the first angular alignment sector 20A, an operating clearance is reserved between the railing 28 and the rotating plate 24. This clearance allows the rotation of the rotating plate 24, but it is nevertheless sufficiently small to allow the railing 28 to retain the entire preform 12 inside the bowl 20. This clearance is thus less than the minimum diameter "D3" of the body 14 of the preform 12.

[0053] As shown in the figure 4 , on this alignment sector 20A, the railing 28 here extends vertically above the rotating plate 24, so that the outer edge 25 of the rotating plate 24 is arranged outside the centrifuge bowl 20.

[0054] During operation of the device 10, as shown in figures 5 et 6 , during a first discharge step, the preforms 12 discharged in bulk by the spillway 30 are projected radially against a receiving portion 28A of the railing 28 under the combined effect of their radial sliding speed at the outlet of the spillway 30 and the centrifugal force produced by the rotation of the rotating plate 24. At the same time, the rotating plate 24 also begins to drive the preforms 12 tangentially downstream in its rotation.

[0055] During a second alignment step, the preforms 12 are held inside the bowl 20 by the railing 28, then, after one or more rebounds against the railing 28, the preforms 12 gradually lose speed in the radial direction. They are then constantly held radially against the railing by centrifugal force. The path followed by the same preform 12 is shown in FIG. figure 6 from its arrival via the spillway 30 to its stable position against the railing 28. The preforms 12 are then driven in a purely tangential movement in a clockwise direction by the plate 24 rotating along the railing 28.

[0056] In this configuration, the preforms 12 naturally occupy the most stable position in which their main axis "A" is oriented in a direction tangent to the rotating plate 24.

[0057] Most of the preforms 12 present in the angular alignment sector 20A of the bowl 20 are thus aligned tangentially against the railing 28, their main axis "A" being oriented substantially tangentially to their direction of movement. The tangential gap between two successive correctly aligned preforms 12 is random because the rotating plate 24 is perfectly flat and does not have any notches for indexing the preforms 12. The preforms 12 can thus be in contact by their ends under the effect of the centrifugal force which forces the preforms 12 to slide relative to each other. The preforms 12 thus optimally occupy the entire peripheral length of the bowl 20.

[0058] The fact that the preforms 12 are held on the rotating plate 24 makes it possible to keep them pressed radially against the railing 28. Thus, the preforms 12 are guided in a stable manner by the railing 28 during their movement around the bowl 20.

[0059] At this stage, the preforms 12 are randomly oriented upstream or downstream without affecting the rest of the process. The preforms 12 thus aligned continue their peripheral movement in the straightening sector 20B.

[0060] As shown in the figure 7 , on the second angular sector 20B for straightening the centrifuge bowl 20, the bowl 20 has a peripheral gap 34 formed by radial spacing of the railing 28 relative to the outer edge 25 of the rotating plate 24. The radial width of the gap 34 is between the maximum diameter "D2" of the body 14 and the diameter "D1" of the support face 18, in this case of the collar. This gap 34 extends to the exit passage 32 of the preforms 12.

[0061] At least along the entire length of the second straightening sector 20B, the railing 28 has a rail 36 for supporting the support face 18. The rail 36 projects radially inward at the same level as the upper face of the rotating plate 24 to delimit the gap 34 outwardly. The rail 36 extends here to the exit passage 32.

[0062] Thus, the preforms 12 are capable of being supported by their support face 18, in this case by their collar, which rests at two diametrically opposite points on the horizontal upper face of the rotating plate 24, on the one hand, and on a horizontal upper face of the rail 36, on the other hand, the body 14 of the preforms 12 being below the level of the rotating plate 24 through said gap 34. The two support points are radially aligned. The rail 36 makes it possible to support the preforms 12 in a stable manner.

[0063] Thus, in a third stage of recovery, as shown in figures 8 et 9 , the preforms 12 aligned during the second step arrive from the first alignment sector 20A by being aligned in an elongated position in a row along the railing 28, their main axis "A" oriented tangentially. The aligned preforms 12 are randomly arranged neck 16 upstream or neck 16 downstream without this having any influence on their straightening.

[0064] When the body 14 of each preform 12 arrives above the gap 34, the body 14 begins to fall, as shown in figures 10 et 11 , thus tilting the preform 12 around a radial axis passing through the support points of the support face 18, in this case the collar, of the preform 12. The tilting continues until the main axis "A" of the preform 12 is vertical, possibly after some swinging around the radial axis. The preform 12 is then supported by its support face 18 resting jointly on the rail 36 and on the rotating plate 24, as indicated in figures 12 et 13 . The preform 12 is thus straightened, neck 16 at the top. The preform 12 thus correctly positioned is guided externally by the rail 36 of the guardrail 28, and it is guided internally by the outer edge 25 of the rotating plate 24.

[0065] During tilting, the main axis "A" of the preform 12 remains in a vertical plane tangent to the movement. Due to the tilting of the main axis "A" in the direction of movement of the preforms 12, the support face 18 of each preform 12 remains permanently in contact with the rotating plate 24 on the one hand, and the rail 36 on the other hand, by its two support points. Thus, each preform 12 is guided in a stable and efficient manner during its straightening.

[0066] As shown in the figure 11 , a transition zone is provided at the upstream end of the angular straightening sector 20B. In this transition zone, the gap 34 is gradually widened until it reaches its final width. To do this, the railing 28 gradually moves radially away from the axis "B" of rotation of the rotating plate 24. This allows the aligned preforms 12 to remain constantly in contact with the railing 28 under the effect of centrifugal force. The preforms 12 are thus guided stably in the aligned position even during their straightening.

[0067] If the guardrail 28 were to have a discontinuity, it would no longer be able to fulfill its guiding role at the level of this discontinuity. The aligned preforms 12 would then risk jumping or finding themselves badly positioned, for example coming to bear at an angle against adjacent preforms and preventing them from being straightened.

[0068] The correctly positioned preforms 12, that is to say thus aligned and straightened, are rotated around their main axis by friction against the outer edge 25 of the peripheral plate 24. The correctly positioned preforms 12 are moved to the periphery of the bowl 20 in the direction of rotation of the rotating plate 24 by rolling against the peripheral railing 28.

[0069] To improve this rolling phenomenon of the correctly positioned preforms 12 and thus increase their speed of advance around the plate 24, the outer edge 25 of the rotating plate 24 advantageously comprises a rolling strip 38 which has a coefficient of friction adapted to allow the body 14 of the preform 12 to roll without slipping against the rolling strip 38. Such an arrangement is for example shown in FIG. figure 7 .

[0070] The correctly positioned preforms 12 are thus conveyed to the third output sector 20C. The third output sector 20C comprises a peripheral zone which is protected by a fixed deflector 44 which is arranged above the rotating plate 24 at a vertical distance less than that of the minimum diameter "D3" of the body 14 of the preforms 12 to prevent incorrectly positioned preforms 12N from coming into contact with the line of correctly positioned preforms 12 in the gap 34. As shown in FIG. figure 3 , the deflector 44 extends in a spiral arm from an upstream end 44A which is arranged at the outer edge 25 of the rotating plate 24, to a downstream end 44B arranged near the center of the rotating plate 24 downstream of the outlet passage 32. The upstream end 44A of the deflector 44 is radially spaced from the railing 28 so as to reserve a passage 46 sufficient to allow the correctly positioned preforms 12 to pass.

[0071] The deflector 44 thus ensures that in the protected area located between the downstream face of the deflector 44 and the railing 28, no incorrectly positioned 12N preform is lying on the rotating plate 24.

[0072] To prevent incorrectly positioned 12N preforms from entering the area protected by the passage 46 or from causing a traffic jam by blocking the passage 46, the invention proposes blowing at least one jet 48 of compressed gas, in particular compressed air, from the outer periphery of the centrifuge bowl 20. More particularly, the jet 48 of gas is here emitted from the outer periphery of the angular straightening sector 20B, upstream of the passage 46, as shown in figures 14 et 15 .

[0073] The gas jet 48 is emitted in a main direction "F" which has at least one radial component "Fr" directed towards the center of the rotating plate 24, called the centripetal component, as illustrated in figure 15 The gas jet 48 passes over the neck 16 of the correctly positioned preforms 12 to drive incorrectly positioned preforms 12N towards the center of the rotating plate 24.

[0074] Indeed, the preforms 12 generally have a neck whose axial height is less than the largest diameter of the preform 12. Thus, an incorrectly positioned preform 12N occupying an elongated or incompletely straightened position will have an upper portion which will extend above the rim of a correctly positioned preform 12. This upper portion will therefore be exposed to the gas jet 48 while the correctly positioned preforms 12 will pass entirely below the gas jet 48.

[0075] Furthermore, as illustrated in the figure 15 , the gas jet 48 has, in vertical radial section, a divergence which allows a lower part of the gas jet 48 to plunge towards the rotating plate 24 behind the correctly positioned preforms 12 to more effectively expel the incorrectly positioned preforms 12N which are lying on the rotating plate 24.

[0076] It has been found that this method for driving out incorrectly positioned 12N preforms is more effective when the gas jet 48 is emitted in a main direction "F" which, in addition to the centripetal component "Fr", has a tangential component "Ft" directed in the opposite direction to the direction of rotation of the rotating plate 24, as illustrated in figure 14 . Indeed, the incorrectly positioned 12N preforms are subjected not only to a centrifugal force, but also to a tangential friction force with the rotating plate 24. The gas jet 48 expels the incorrectly positioned 12N preforms with a force that exceeds all of these forces experienced, making it possible to effectively expel the incorrectly positioned 12N preforms towards the centre of the rotating plate 24, and more particularly, towards the first angular alignment sector 20A. Thus, the expelled 12N preforms have a high probability of being correctly positioned during a new revolution of the centrifuge bowl 20.

[0077] In the example shown in the figure 3 , several gas jets 48, here four, are emitted along a downstream end portion of the angular straightening sector 20B. At least one of the gas jets 48 is blown from an area located near the downstream end of the straightening sector 20B, and more particularly near the passage 46, in order to guarantee that no incorrectly positioned preform 12N enters the protected area.

[0078] The emission of such a jet 48 of gas has many advantages.

[0079] Thus, incorrectly positioned 12N preforms are not driven out by percussion with a solid element, which prevents any degradation of the preform, but also the wear of such a solid element.

[0080] In addition, the gas jet 48 not only allows the incorrectly positioned 12N preforms that are lying on the rotating plate 24 to be expelled against the correctly positioned 12 preforms, but also the incorrectly positioned 12N preforms that are nested in correctly positioned 12 preforms. The neck 16 of such nested 12N preforms in fact passes into the path of the gas jet 48.

[0081] The gas jet 48 is blown continuously so that any incorrectly positioned 12N preforms can be blown out at any time.

[0082] Alternatively the gas jet is emitted in pulses of sufficiently high frequency to ensure that any incorrectly positioned 12N preforms passing within range will be exposed to the gas jet 48.

[0083] It has been shown in more detail at the figure 16 a device 50 for blowing the jet 48 of compressed gas. The blowing device 50 mainly comprises a nozzle 52 for blowing the jet 48 of compressed gas which is mounted on a support element fixed relative to the support table 26 and a source 57 of compressed gas which supplies the nozzle 52.

[0084] In the example shown in the figure 3 , several nozzles 52 are arranged around the periphery of the centrifuge bowl 20. These nozzles 52 have an identical structure and a similar operation. Only one nozzle 52 will therefore be described below. The nozzles 52 are here supplied by a common source 57 of compressed gas.

[0085] The source 57 of compressed gas is for example formed by a compressor, shown schematically in figure 17 , which is connected to the nozzle 52 via a supply line 56; as shown in figure 17 .

[0086] The nozzle 52 comprises a body 60 which encloses a chamber 62. The chamber 62 here has an elongated shape in a tangential direction which is delimited tangentially between a radial vertical upstream wall 62A and a radial vertical downstream wall 62B. In a non-limiting manner, in the example of the figure 17 , the supply line 56 is connected to the upstream wall 62A of the chamber 62.

[0087] In a variant of the invention not shown, the pipe is connected to the downstream wall of the chamber.

[0088] Optionally, the nozzle 52 is here provided with a pressure gauge 64 which is connected to the chamber 62 in order to allow visual monitoring of the pressure of the compressed gas.

[0089] The chamber 62 opens radially towards the centrifuge bowl 20 via an outlet orifice. The outlet orifice here has the form of a horizontal outlet slot 66 whose length extends in a tangential direction. Thus, the gas jet 48 advantageously has the shape of an air blade which makes it possible to intercept a greater number of preforms 12 than a narrower gas jet. The slot 66 extends from an upstream end 66A to a downstream end 66B. The upstream end 66A is substantially in the extension of the upstream wall 62A of the chamber 62, while the downstream end 66B is offset tangentially upstream relative to the downstream wall 62B of the chamber 62. Thus, a downstream end section of the chamber 62 forms a downstream dead end 68 which is not radially open towards the centrifuge bowl 20.The presence of the downstream dead end 68 makes it possible to deflect the gas jet 48 radially upstream so that its main emission direction has a tangential component in accordance with the teachings of the invention.

[0090] The slot 66 is here arranged in a spout 70 which projects radially towards the inside of the centrifuge bowl 20 from the body 60 of the nozzle 52. The spout 70 is fixed to the body 60.

[0091] The nozzle 52 is here located radially outside the bowl. The support element is here formed by the railing 28. More particularly, the nozzle 52 is here arranged in an opening 58 which radially passes through the railing 28. The opening 58 here opens towards the top of the railing 28. Thus, the nozzle 52 is located as close as possible to the line of correctly positioned preforms 12.

[0092] The alignment device 10 is intended to process batches of preforms 12 of different formats. In particular, the weight and the height of the neck 16 of the preforms are likely to vary from one format to another.

[0093] To enable the height of the nozzle 52 to be adapted as a function of the height of the neck 16 of the preforms 12, the position of the blowing nozzle 52 is adjustable in height relative to the railing to prevent the gas jet 48 from disturbing the movement of the correctly positioned preforms 12. In the example shown in the figures, the nozzle 52 is mounted to slide vertically in the railing 28. The body 60 of the nozzle 52 here comprises two tangential end ears 72 which are received in sliding motion in associated vertical grooves 74 of the railing 28 arranged on either side of the opening 58.

[0094] Furthermore, a horizontal plate 76 forms a bridge over the opening 58. The plate 76 is fixed to the railing, here by means of two screws 78. As is particularly visible in the figure 18 , a vertical rod 80 is mounted to rotate about its axis and fixed vertically in the plate 76. A lower end threaded portion of the rod 80 is screwed into a corresponding thread in the body 60 of the nozzle 52. The rod 80 is capable of being rotated by a handle 82 fixed to an upper end of the rod 80, above the plate 76 to control the vertical position of the body 60 of the nozzle 52 relative to the railing 28. Thus, the rod 80 has the function of controlling the vertical sliding of the nozzle 52, and of maintaining the nozzle 52 in the selected vertical position.

[0095] Furthermore, it is preferable to be able to adapt the power of the gas jet 48 according to the weight of the preforms 12. Indeed, a gas jet 48 that is too weak would not allow the incorrectly positioned preforms 12N to be effectively expelled, while a gas jet 48 that is too powerful would risk propelling the incorrectly positioned preforms 12N too quickly towards the other side of the centrifuge bowl 20, with a risk of damaging the preforms and / or certain components of the alignment and straightening device 10.

[0096] For this purpose, the blowing device 50 comprises means for regulating the power of the gas jet 48.

[0097] In the present case, the blowing nozzle 52 comprises an adjustable element 84 for closing off the gas passage section to enable the power of the gas jet 48 to be adjusted. The closing element 84 thus enables the gas passage section in the outlet slot 66 to be modified.

[0098] As is particularly visible in the figures 17 And 19 , the closure element 84 is here formed by a rod with a tangential axis, that is to say arranged in the lengthwise direction of the outlet slot 66. The closure element 84 is mounted to slide in a tangential direction in the outlet slot 66. For this purpose, the spout 70 has tangential guide slides 86 arranged vertically on either side of the slot 66 which receive the closure element 84 in sliding.

[0099] The closure element 84 has a height sufficient to block the passage of gas in the slot 66. The gas passage section in the slot 66 is delimited tangentially between the upstream end 66A of the slot 66 and a free upstream end 84A of the closure element 84. The adjustment of the passage section is controlled by sliding the closure element 84 between: an extreme open position in which the closure element 84 is retracted, here completely, towards the downstream end 66B of the slot 66, as shown in figures 17 And 19 in solid lines; and an extreme closed position in which the closure element 84 is partially extended towards the upstream end 66A of the slot 66, so as to reduce the gas passage section by increasing the tangential dimension of the dead end 68, as shown in broken lines in figures 17 And 19 .

[0100] In the embodiment shown in the figures, the outlet speed of the compressed gas increases progressively as the closure element 84 slides from its extreme open position to its extreme closed position. Thus, the jet 48 of compressed gas is more powerful in the extreme closed position than in the extreme open position.

[0101] The pressure of the compressed gas supplying the nozzle 52 is here constant regardless of the setting of the shut-off element 84. The power of the gas jet 48 is thus determined solely as a function of the position occupied by the shut-off element 84 between its two extreme positions.

[0102] According to a variant of the invention not shown, the power of the gas jet can also be controlled by regulating the pressure of the compressed gas.

[0103] To enable its position to be controlled, the closure element 84 is here connected to a control plate 88 which is arranged on an upper face of the spout 70 of the nozzle 52. As shown in figure 19 , the control plate 88 is connected to the closure element 84 by means of a fixing rod 90 mounted to slide in an oblong slot 92 of the spout 70. The control plate 88 can be locked by tightening a braking screw 94 screwed into the spout 70 in order to lock the control plate 88 by tightening between the head of the braking screw 94 and the upper face of the spout 70.

[0104] The blowing method and device 50 produced according to the teachings of the invention make it possible to expel almost all of the incorrectly positioned preforms 12N before they reach the angular outlet sector 20C. To improve the efficiency of the method, the invention proposes arranging several blowing devices 50 successively in a downstream portion of the angular straightening sector 20B extending for example over the downstream half of the angular straightening sector 20B.

[0105] Although this method and the blowing device 50 for its implementation are extremely effective, it is of course possible to combine it with other means of sorting incorrectly positioned preforms such as the primary and / or secondary untangling wheels described in application FR 3,035,090 A1.

[0106] We have represented at the figures 14 And 16 a primary detangling wheel 96 which is interposed between the last blowing device 50 and the deflector 44.

[0107] The invention thus provides a very efficient method for re-dispatching the incorrectly positioned preforms 12N to the angular alignment sector 20A, for preforms of various formats and for very high preform flow rates. The method also makes it possible to avoid damaging preforms 12 and / or elements of the alignment and straightening device 10.

Claims

1. Method for sorting incorrectly aligned preforms (12N) from a row of correctly positioned preforms (12) in a device (10) for aligning preforms in a row and straightening preforms, which comprises a centrifuge bowl (20) formed by: - a horizontal circular turntable (24) turning about a vertical axis (B); - a fixed peripheral guard-bar (28); - at least one angular sector (20B) for straightening the preforms (12) along which the bowl (20) has a peripheral gap (34) in order to allow the straightening of preforms (12), which are aligned by a body (14) of the preforms (12) being tilted into the gap (34) while the neck (16) is supported above the gap (34); - at least one angular outlet sector (20C) for the correctly positioned preforms (12), which is arranged downstream of the angular straightening sector (20B) in the direction of rotation of the turntable (24); characterized in that the method consists in blowing at least one jet (48) of compressed gas from the outer periphery of the centrifuge bowl (20) towards the inside of the centrifuge bowl (20).

2. Method according to the preceding claim, characterized in that the jet (48) of gas is released in a direction (F) having at least one radial component directed towards the centre of the turntable (24), referred to as centripetal component (Fr), the jet (48) of gas passing above the neck (16) of the correctly positioned preforms (48) in order to force incorrectly positioned preforms (12N) towards the centre of the turntable (24).

3. Method according to the preceding claim, characterized in that the jet (48) of gas is released in a direction (F) having, in addition to the centripetal component (Fr), a tangential component (Ft) directed counter to the direction of rotation of the turntable (24).

4. Method according to any one of the preceding claims, characterized in that the jet (48) of gas is blown from a region situated near the downstream end of the straightening sector (20B).

5. Method according to any one of the preceding claims, characterized in that the jet (48) of gas is blown continuously.

6. Device (10) for aligning preforms in a row and straightening preforms, which comprises a centrifuge bowl (20) formed by: - a horizontal circular turntable (24) turning about a vertical axis (B); - a fixed peripheral guard-bar (28); - at least one angular sector (20B) for straightening the preforms (12) along which the bowl (20) has a peripheral gap (34) in order to allow the straightening of preforms (12), which are aligned by a body (14) of the preforms (12) being tilted into the gap (34) while the neck (16) is supported above the gap (34); - at least one angular outlet sector (20C) for the correctly positioned preforms (12), which is arranged downstream of the angular straightening sector (20B) in the direction of rotation of the turntable (24); characterized in that it comprises at least one blowing device (50) comprising a nozzle (52) for blowing the jet (48) of compressed gas, said nozzle being mounted on a fixed support element situated radially outside the bowl (20) and a source (57) of compressed gas that supplies the nozzle (52).

7. Device (10) for aligning preforms in a row and straightening preforms according to the preceding claim, characterized in that the blowing device (50) comprises means for regulating the power of the jet (48) of gas.

8. Device (10) for aligning preforms in a row and straightening preforms according to the preceding claim, characterized in that the regulating means comprise an adjustable shut-off element (84), which is arranged in the nozzle (52) in order to modify the gas passage section.

9. Device (10) for aligning preforms in a row and straightening preforms according to the preceding claim, characterized in that the shut-off element (84) is mounted so as to slide.

10. Device (10) for aligning preforms in a row and straightening preforms according to any one of Claims 6 to 9, characterized in that the position of the blowing nozzle (52) is height-adjustable in relation to the support element.

11. Device (10) for aligning preforms in a row and straightening preforms according to either one of Claims 8 and 9, characterized in that the nozzle (52) comprises a pressure chamber (62) that opens towards the outside via a horizontal outlet slot (66) that extends from an upstream wall (62A) of the pressure chamber (62) to a free end (84A) of the shut-off element (84), the shut-off element (84) being mounted so as to slide horizontally in order to allow the gas passage section to be modified.