CONVEYOR BELTS FOR HOLLOW BODIES THROUGH A HEATING STATION

Description

TECHNICAL FIELD OF THE INVENTION

[0001] The invention relates to a method for controlling a hollow body conveyor through a heating station for a thermoplastic material container manufacturing plant, comprising: a heating tunnel defining a heating path; a conveyor comprising at least one running rail forming a circuit, and shuttles capable of circulating along the rail while carrying at least one hollow body, each shuttle being individually controlled in movement, the rail having a heating section for transporting the hollow bodies along the heating path; an inlet device for the hollow bodies to be heated bringing the hollow bodies to a loading section of the running rail for loading them onto the shuttles, two successive shuttles circulating with a first determined inlet spacing on this loading section; an outlet device for the hot hollow bodies which recovers the hollow bodies carried on the shuttles circulating on an unloading section of the running rail. TECHNICAL BACKGROUND OF THE INVENTION

[0002] The manufacture of thermoplastic containers, such as bottles, flasks, etc., is generally carried out from preforms, sometimes called blanks, which are introduced into a molding device with which forming means, for example blowing or stretch-blow molding, are associated.

[0003] In the remainder of the description and in the claims, the preforms and the finished containers will be designated by the generic term "hollow body". Traditionally in this technical field, the preform and the finished container have an identical neck or neck. Therefore, the same member for supporting a preform by its neck is also suitable for supporting a finished container.

[0004] The container manufacturing plant is supplied with preforms that are not ready for direct forming due to their insufficient temperature. Prior to blow molding or stretch blow molding, the preforms are therefore heated in a heating station to give them a structure that is sufficiently malleable for the blow molding operation.

[0005] Such large-scale container manufacturing facilities are equipped with a heating station comprising a heating tunnel equipped with means for heating the preforms. This heating tunnel determines a heating path along which the preforms are generally transported by a conveyor at a stabilized speed without stopping. The tunnel is of sufficient length to allow the preforms to be heated as they pass through it.

[0006] The conveyor comprises individual preform support members which move along a closed circuit, a portion of which transports the preforms along the heating path which passes through the heating tunnel. The support members are generally formed by mandrels which are capable of rotating the transported preforms around their axis to ensure uniform heating of the preforms.

[0007] Furthermore, the preforms are fed one after the other by an infeed device to an infeed zone in the heating station. The infeed device is generally formed by a rotating wheel equipped at its periphery with preform support members, such as notches or grippers. The preforms are thus loaded onto the conveyor at the infeed zone, in which the path of the support members of the conveyor is tangent to the path of the preform support members of the infeed device.

[0008] To enable the preforms to be transferred from the infeed device to the conveyor, the conveyor support members must travel in a coordinated manner, both in position and speed, with the support members of the infeed device in the infeed zone. On the infeed wheel, the preforms are spaced apart by a pitch determined by their direction of travel. Therefore, it is imperative that the individual support members of the conveyor be spaced apart by a distance equal to the infeed pitch of the preforms as they pass over the infeed zone.

[0009] The same problem arises for the transfer of hot preforms, at the exit of the heating path, to an exit device similar to the entry device.

[0010] Furthermore, the heating station has a particularly long and bulky heating tunnel. It would therefore be interesting to be able to create a shorter, and therefore more compact, heating tunnel without compromising the heating quality of the preforms.

[0011] Furthermore, in the heating stations known from the state of the art, the preforms moving through the heating tunnel are spaced apart from each other by a relatively large pitch. As a result, a large part of the heating radiation emitted by the heating means is produced in pure loss, because it passes into the spaces left between two successive preforms without heating the latter. Thus, a large amount of energy is wasted.

[0012] According to another problem, the hot preforms are intended to feed at least one subsequent processing station, in particular the forming station. It often happens that the pitch between two successive preforms in the following processing station is different from the pitch between two successive preforms transported by the input device. Therefore, a transfer device capable of changing the pitch between two preforms is generally interposed in the flow of preforms downstream of the furnace and upstream of said following processing station.

[0013] Such a transfer device with pitch change is not only expensive, but also has the disadvantage of increasing the size of the forming installation.

[0014] Also known are documents US 5,972,255, EP0571262, DE102008042543 and EP2848382.

[0015] US 5,972,255 describes a method and device for blow molding directly after injection of the preforms in which the temperature of the preforms only needs to be raised slightly and the distance of the preforms in the oven is the same as outside said oven. Alternatively, the device can be used to heat cold preforms. The preforms then have to stay longer in the oven, which is why the pitch between the supports is reduced in the oven. The exact location of the pitch reduction or the pitch increase is, however, not explicitly described in this document.

[0016] Document EP0571262 describes a heat treatment unit having a succession of ovens to increase the crystallinity rate of PET.

[0017] Document DE102008042543 describes a pitch changing device for a blow molding machine.

[0018] Document EP2848382 describes an installation with an oven, a blower and individually controlled transport elements. Document EP 1070579 A1 describes a support for four preforms allowing the distance between the preforms to be modified. BRIEF SUMMARY OF THE INVENTION

[0019] The invention relates to a conveyor of hollow bodies through a heating station for an installation for manufacturing containers made of thermoplastic material, comprising: a heating tunnel defining a heating path; a conveyor comprising at least one running rail forming a circuit and shuttles capable of circulating along the rail while carrying at least one hollow body, each shuttle being controlled in movement individually, the rail having a heating section for transporting the hollow bodies along the heating path; an entry device for the hollow bodies to be heated bringing the hollow bodies to a loading section of the running rail for loading them onto the shuttles, two successive shuttles circulating with a first entry spacing E1 determined on this loading section;a hot hollow body outlet device which recovers the hollow bodies loaded onto the shuttles running on an unloading section of the scrolling rail;said conveyor being remarkable in that each shuttle comprises a first support member for a first hollow body and a second support member for a second hollow body, each shuttle thus being capable of simultaneously carrying two hollow bodies, the support members of a shuttle being mounted to move on said shuttle between an extended position in which the support members are spaced apart from said first entry spacing E1 in the direction of movement of the shuttle, and a close position in which the support members are brought together in the direction of movement of this shuttle, in such a way that two successive shuttles circulating on the unloading section are spaced apart by a determined exit spacing E3 which is different from the first entry spacing E1.;

[0020] According to other conveyor characteristics: the shuttle comprises an arm defining an orientation axis, each end of said arm comprising one of the support members, said arm being mounted to be movable in rotation relative to the shuttle around a main axis between a straight position corresponding to the direction of movement of the shuttle, and an oblique position inclined relative to the straight position; the conveyor comprises an actuator which is capable of controlling the arm between its straight position and its oblique position; the actuator is capable of being actuated by an actuating member carried by one of the adjacent shuttles. BRIEF DESCRIPTION OF THE FIGURES

[0021] 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 1is a top view which schematically represents a container manufacturing installation equipped with a heating station comprising a conveyor produced according to a first embodiment of the invention; the Figure 2 is a side view which represents a part of the loading section of the conveyor on which two shuttles circulate, spaced longitudinally by a first spacing; Figure 3 is a side view which represents a part of the heating section of the conveyor on which four shuttles circulate, spaced longitudinally by a second spacing; Figure 4 is a side view which represents a part of an unloading section of the conveyor on which two shuttles circulate, spaced longitudinally by a third spacing; Figure 5 is a top view which represents the unloading section of the conveyor according to a variant of the first embodiment of the invention; Figure 6is a top view similar to that of the Figure 1 which represents a second embodiment of the conveyor. DETAILED DESCRIPTION OF THE FIGURES

[0022] In the remainder of the description, elements having an identical structure or similar functions will be designated by the same references.

[0023] In the remainder of the description, a longitudinal direction will be adopted, directed from back to front in the direction of movement of the preforms, a vertical direction, directed from bottom to top orthogonal to the plane of movement of the preforms, and a transverse direction which is perpendicular to the two preceding directions.

[0024] We represented at the Figure 1a part of a large-scale manufacturing facility 10 for containers made of thermoplastic material such as polyethylene terephthalate or PET. The manufacturing facility 10 is here intended to form containers from preforms 12 to be heated.

[0025] The manufacturing installation 10 comprises a station 14 for heating the preforms 12 and a station 16 for forming, here by blowing or stretch-blow molding, the preforms 12 previously heated by said heating station 14.

[0026] The heating station 14 comprises a heating tunnel 18, which is here made in three successive sections. The heating tunnel 18 has been shown schematically. The heating tunnel 18 defines a heating path which is intended to be traveled by each preform 12.

[0027] Conventionally, such a heating tunnel 18 (respectively each section of the tunnel) is delimited by two side walls (not shown) which form a tunnel. At least one of the walls is provided with heating means, such as infrared lamps (not shown), emitting radiation heating the preforms. The heating tunnel 18 can also be equipped with ventilation means making it possible to promote uniform heating of the preforms and making it possible to avoid overheating of certain components of the heating station 14.

[0028] The heating station 14 also comprises a conveyor 20 which is intended to transport each preform 12 through the heating tunnel 18. In normal operation of the manufacturing installation 10, the conveyor 20 is here intended to transport the preforms 12 continuously, that is to say without interruption of the movement of the preforms 12. The length of the heating tunnel 18 and the power of the heating means are adapted so that the preforms 12 emerge heated to a temperature sufficient for their forming by the forming station 16.

[0029] The conveyor 20 comprises at least one running rail 22 which forms a closed circuit and on which shuttles 24 circulate. Each shuttle 24 is controlled individually in movement, that is to say independently of the other shuttles 24.

[0030] In a variant of the invention (not shown), the rail runs across the heating station in an open circuit, the rail also serving upstream or downstream treatment stations. Such an arrangement is referred to as "sequential".

[0031] The shuttles 24 and the scroll rail 22 are part of a linear motor. In such a motor, the scroll rail 22 comprises a stator which is formed of a series of windings (not shown) which are distributed along the rail 22. Each winding is individually controlled to locally induce a magnetic field independently of the other windings.

[0032] The windings are, for example, controlled by an electronic control unit (not shown) which is programmed appropriately.

[0033] Each shuttle 24 is equipped with at least one permanent magnet which reacts to the magnetic field induced by each winding of the rail 22 by causing the shuttle 24 to move along the rail 22. In addition, each shuttle 24 is guided in movement along the running rail 22.

[0034] The pitch between two windings is sufficiently small to allow the windings of the scrolling rail 22 to be controlled so as to cause the movement of each shuttle 24 independently of the other shuttles 24.

[0035] Such a linear motor is sold, for example, by Beckhoff under the name "XTS". For further details on this technology, please refer to documents US-A1-2013 / 0.119.897, US-A1-2013 / 0.035.784, WO-A1-2013 / 143.783 or WO-A1-2013 / 143.950.

[0036] Generally speaking, this technology implemented within the framework of the invention makes it possible to move all the shuttles 24 in a row in the same direction of movement along the circuit, here a counterclockwise direction. The speed of movement of each shuttle 24 can be controlled individually by an electronic control unit (not shown).

[0037] Each shuttle 24 comprises at least one individual support member for a preform 12.

[0038] In the embodiment of the invention shown in figures 1 to 4 , each shuttle 24 comprises a single individual support member for a preform 12. In the example shown in figures 2 to 4 , it is a mandrel 26 which is inserted vertically into a neck of the preform 12. Thus, each shuttle 24 is capable of transporting a preform 12.

[0039] The mandrel 26 is for example mounted to slide vertically on the shuttle 24 between a low preform gripping position and a high preform ejection position. The sliding is for example controlled by an electric motor or by a cam system.

[0040] The 22 scroll rail can be divided into several sections.

[0041] At least one section called "heating section 22B" of the running rail 22 allows the shuttles 24 to transport the preforms 12 along the heating path. The heating section 22B extends from an inlet 28 of the heating tunnel 18 to an outlet 30 of the heating tunnel 18.

[0042] A section called the "loading section 22A" of the running rail 22 is arranged upstream of the inlet 28 of the heating tunnel 18, according to the direction of circulation of the shuttles 24. The preforms 12 to be heated are loaded onto the shuttles 24 circulating on this section 22A. Thus, the shuttles 24 arrive on this loading section 22A "empty" and they leave it loaded with a preform 12 to be heated.

[0043] A section called the "unloading section 22C" of the running rail 22 is interposed between the outlet 30 of the heating tunnel 18 and the loading section 22A, according to the direction of circulation of the shuttles 24. The hot preforms 12 are unloaded from shuttles 24 circulating on this unloading section 22C. Thus, the shuttles 24 arrive on this unloading section 22C each loaded with a hot preform 12 after its passage through the heating tunnel 18 and they leave it "empty".

[0044] The manufacturing installation 10 also comprises an input device 32 for the preforms 12 to be heated, bringing the preforms 12 to be heated to the loading section 22A of the running rail 22 for loading them onto the shuttles 24. The input device 32 is capable of bringing, to the loading section 22A, each preform 12 successively, two successive preforms 12 being separated by a determined input pitch according to their direction of movement.

[0045] In the example shown in the Figure 1 , the input device 32 is formed by a wheel 34 with notches 36. The wheel 34 is rotatably mounted around a vertical axis. The wheel 34 has at its periphery notches 36, each of which is capable of carrying a preform 12 in association with known means not shown, such as peripheral guide guides. Two neighboring notches 36 are circumferentially spaced apart from said determined input pitch.

[0046] In the embodiment shown in the Figure 1 , the installation 10 also comprises a device 38 for outputting the hot preforms 12 which is capable of transferring the preforms 12 from the unloading section 22C of the running rail 22 to the forming station 16. The output device 38 is designed to load the preforms 12 one after the other, two successive preforms 12 being separated by a determined output pitch according to their direction of movement.

[0047] In the example shown in the Figure 1 , the output device 38 is formed by a wheel 40 equipped at its periphery with a plurality of arms 42. Each arm 42 comprises at its free end a support member such as a clamp 44 capable of gripping a preform 12 by its neck.

[0048] The forming station 16 is here formed by a carousel 46 (of which only a part is shown) which carries a plurality of molding units 48 at its periphery. The carousel 46 is rotatably mounted so as to move the preforms 12 then the containers during their forming. Such a forming station is well known and will therefore not be described in more detail subsequently.

[0049] Generally, the circumferential gap between two neighboring molding units 48 is greater than the determined exit pitch of the hot preforms 12. In this respect, the arms 44 are generally pivotally and / or slidably mounted on the wheel 40 to allow the pitch to be changed between two successive preforms 12 during their transport to the forming station 16. Thus, the preforms 12 are spaced apart by a pitch adapted to the spacing between two molding units 48 during their transfer to the forming station 16.

[0050] A method of controlling the conveyor 20 is now described, making it possible to take full advantage of the energy used by the heating means of the heating tunnel 18.

[0051] In this embodiment, the spacing between two successive shuttles 24 is equal to the longitudinal spacing between the two support members of these two shuttles 24, which members are here constituted by the mandrels 26.

[0052] As shown in the Figure 2 , when they circulate on the loading section 22A of the scrolling rail 22, two successive shuttles 24 circulate with a first determined entry spacing "E1". This first spacing "E1" corresponds to the determined entry pitch of the preforms 12 to be heated. Thus, each shuttle 24 passes in coincidence with a notch 36 of the entry device 32 allowing the mandrel 26 to be inserted into the neck of the preform 12 while the latter is still supported by the notch 36.

[0053] Then, at least from their entry onto the heating section 22B, the shuttles 24 are controlled so that the spacing between two successive shuttles is reduced relative to said first entry spacing "E1". The spacing between two successive shuttles 24 remains reduced relative to said first entry spacing "E1" as long as they travel on the heating section 22B, that is to say at least until their exit from the heating tunnel 18. This has the effect of reducing the pitch between two preforms 12 during their heating.

[0054] Thus, a greater proportion of the radiation emitted by the heating means is usefully absorbed by the preforms 12 for their heating.

[0055] Furthermore, this allows a greater quantity of preforms to be circulated simultaneously in the heating tunnel 18.

[0056] In the embodiment shown in the Figure 3, the spacing between two successive shuttles 24 remains equal to a second constant spacing "E2", called the heating spacing, which does not change as long as they circulate on the heating section 22B of the running rail 22.

[0057] Then, when the shuttles 24 arrive on the unloading section 22C, they are controlled so that two successive shuttles 24 circulate with a third determined exit spacing "E3", as illustrated by the Figure 4 This third spacing "E3" is determined so as to minimize the change in pitch between two successive preforms 12 during their transport by the output device 38.

[0058] Each shuttle 24 is more particularly controlled so as to circulate in coincidence with a corresponding support member 44 of the output device 38 to allow the transfer of the preforms 12 from the conveyor 20 to the output device 38.

[0059] In a variant of the invention (not shown), the spacing between two successive shuttles circulating on the heating section is capable of varying, while remaining less than the inlet spacing. Such a variation in the spacing makes it possible in particular to more precisely control the heating profile of the preforms, particularly when certain portions of the body of the preforms must be heated preferentially. In other words, the spacing E2 can vary.

[0060] According to the embodiment shown in Figures 2 and 4 , the third outlet spacing "E3" is different from the first inlet spacing "E1". Here the third outlet spacing "E3" is greater than the first inlet spacing "E1". Therefore, the third outlet spacing "E3" is also greater than the second heating spacing "E2".

[0061] Generally speaking, the second heating spacing "E2" is advantageously less than the first inlet spacing "E1" and the third outlet spacing "E3".

[0062] We represented at the Figure 5 a variant of this first embodiment, in which the third spacing "E3" between the shuttles 24 circulating on the unloading section 22C coincides with the pitch between two molding units 48 of the forming station 16. In this case it is no longer necessary to arrange an output device 38 capable of modifying the pitch between the preforms 12 since the preforms are already spaced apart from the pitch adapted to the forming station 16.

[0063] As shown in the Figure 5, the preforms 12 are here directly transferred from the conveyor 20 to the forming station 16 without interposition of intermediate transport means between the heating station 14 and the forming station 16. Thus, the hot preforms 12 are directly deposited in the molding units by the shuttles 24.

[0064] This arrangement allows for a very compact manufacturing installation. It also reduces the transfer time between heating the preforms and forming them.

[0065] We represented at the Figure 6 a second embodiment of the manufacturing installation 10. This installation 10 is similar to that described in the first embodiment shown in Figure 1 . Only the differences with this first embodiment will therefore be described subsequently.

[0066] In this second embodiment, each shuttle 24 comprises a first member 26A for supporting a first preform 12 and a second member 26B for supporting a second preform 12. The shuttle 24 is thus capable of simultaneously carrying two preforms 12. Each support member 26A, 26B is for example formed by a mandrel.

[0067] The support members 26A, 26B are mounted to move on the shuttle 24 between an extended position in which the support members 26A, 26B are spaced apart from the first entry step of the preforms in the direction of movement of the shuttle 24, and a close position in which the support members 26A, 26B are brought closer to each other in the direction of movement of the shuttle 24.

[0068] For this purpose, the shuttle 24 comprises an arm 50 defining an orientation axis. Each end of said arm 50 comprises one of the support members 26A, 26B.

[0069] The arm 50 is itself pivotally mounted on the shuttle 24 around a vertical main axis between a straight position corresponding to the direction of movement of the shuttle 24, and an oblique position inclined relative to the straight position. The pivoting of the arm 50 between its two positions is for example controlled by an actuator (not shown) on board the shuttle 24.

[0070] During operation of the conveyor 20, the shuttles 24 running on the loading section 22A of the running rail 22 are controlled to be spaced apart by a first spacing "E1" which is equal to twice the determined entry pitch of the preforms 12. In addition, the arm 50 is controlled in its straight position. Thus, all the support members 26A, 26B, in their extended position, are spaced apart by the same pitch as the entry pitch of the preforms 12.

[0071] When the shuttles 24 travel on the heating section 22B of the running rail 22, the arms 50 are controlled towards their oblique position. This allows the shuttles 24 to be controlled so as to be spaced apart by a second spacing "E2" which is much less than the first spacing "E1". The shuttles 24 are more particularly controlled so that the preforms 12 are distributed over two rows, as shown in Figure 6 The preforms 12 of the first row are carried by the transport members 26A arranged at the front of the shuttles 24 while the preforms 12 of the second row are carried by the transport members 26B arranged at the rear of the shuttles 24.

[0072] Furthermore, in the oblique position, the arm 50 forms an angle with the direction of movement of the shuttles 24, for example an angle of 45°, so that the preforms 12 of the first row are offset longitudinally between two preforms 12 of the second row.

[0073] In this position and with this spacing "E2" between the shuttles 24, the support members 26A, 26B occupy their close position. This particularly compact arrangement makes it possible to circulate a large quantity of preforms 12 simultaneously in the heating tunnel 18 while allowing all the preforms 12, regardless of their row, to be exposed to the same quantity of heating radiation as the other preforms 12.

[0074] In this second embodiment, the entry pitch of the preforms is equal to the exit pitch of the preforms. Thus, when they travel on the unloading section 22C, the shuttles 24 are controlled to be spaced apart from said first spacing "E1" which is equal to twice the determined entry pitch of the preforms 12. In addition, the arm 50 is controlled in its straight position. Thus, all the support members 26A, 26B, in their extended position, are spaced apart by the same pitch as the exit pitch of the preforms 12.

[0075] The actuator is for example a stand-alone actuator, such as a motor, which is on board the associated shuttle.

[0076] In a variant of the invention not shown, the actuator requires external intervention to be actuated. This is for example a cam control device. A cam follower is for example on board the shuttle, while a cam path arranged parallel to the circulation rail makes it possible to act on the cam follower to actuate the arm.

[0077] In a variant of the invention not shown, the actuator is capable of being actuated by an actuating member carried by one of the adjacent shuttles. Thus, when the spacing between two shuttles 24 is reduced, a pusher of a shuttle 24 is capable of coming into contact with a pivoting mechanism of an adjacent shuttle 24 to control the pivoting of the arm 50. This is for example a cam device or a meshing device.

[0078] The control method implemented according to the teachings of the invention thus makes it possible to circulate a greater number of preforms in the heating tunnel, independently of the entry pitch and the exit pitch of the preforms.

[0079] Of course, the method is not limited to the embodiment shown in the figures. For example, a station for processing the preforms and / or final containers could be interposed between the furnace outlet and the unloading section. Such an arrangement is particularly advantageous in a so-called "sequential" arrangement of the processing stations, as explained previously. In this case, the conveyor makes it possible to transport a hollow body from its initial state in the form of a preform, then, after the forming of said preform, into its final state as a finished container.

[0080] In addition, the control method also makes it possible to modulate the spacing between two shuttles so as to space the preforms of a first entry step on the loading section 22A, a second heating step on the heating section 22B and a third exit step on the unloading section 22C. These three steps can be different from each other.

Claims

1. Conveyor (20) for conveying hollow bodies (12) through a heating station (14) for an installation (10) for manufacturing containers made of thermoplastic material, comprising: - a heating tunnel (18) defining a heating path; - a conveyor (20) comprising at least one running rail (22) forming a circuit and shuttles (24) that are able to circulate along the rail (22) while carrying at least one hollow body (12), the movement of each shuttle (24) being controlled individually, the rail (22) having a heating portion (22B) for transporting the hollow bodies (12) along the heating path; - a device (32) for inputting the hollow bodies (12) to be heated, which brings the hollow bodies (12) as far as a loading portion (22A) of the running rail (22) for loading them onto the shuttles (24), two successive shuttles (24) circulating on this loading portion (22A) with a determined first input spacing (E1); - a device (38) for outputting the hot hollow bodies (12), which recovers the hollow bodies (12) carried on the shuttles (24) circulating on an unloading portion (22C) of the running rail (22), characterized in that each shuttle (24) comprises a first member (26A) for supporting a first hollow body (12) and a second member (26B) for supporting a second hollow body (12), each shuttle (24) thus being able to simultaneously carry two hollow bodies (12), the support members (26A, 26B) of a shuttle (24) being mounted on said shuttle (24) so as to be able to move between an extended position, in which the support members (26A, 26B) are spaced apart by said first input spacing (E1) in the direction of movement of the shuttle (24), and a close position, in which the support members (26A, 26B) are close to one another in the direction of movement of this shuttle (24), in such a manner that two successive shuttles (24) circulating on the unloading portion (22C) are spaced apart by a determined output spacing (E3) that is different to the first input spacing (E1).

2. Conveyor (20) according to Claim 1, characterized in that each shuttle (24) comprises an arm (50) defining an orientation axis, each end of said arm (50) comprising one of the support members (26A, 26B) of its respective shuttle, said arm (50) being mounted so as to be able to rotate with respect to the shuttle (24) about a main axis between a straight position corresponding to the direction of movement of the shuttle (24) and an oblique position that is inclined with respect to the straight position.

3. Conveyor (20) according to either one of Claims 1 and 2, characterized in that the hollow bodies (12) of a first row are carried by the transport members (26A) arranged at the front of the shuttles (24), while the hollow bodies (12) of a second row are carried by the transport members (26B) arranged at the rear of the shuttles (24).

4. Conveyor (20) according to either one of Claims 2 and 3, characterized in that, in the oblique position, the arm (50) forms an angle of 45° with the direction of movement of the shuttles (24) so that the hollow bodies (12) of the first row are longitudinally offset between two hollow bodies (12) of the second row.

5. Conveyor (20) according to either one of Claims 3 and 4, characterized in that it comprises an actuator, which is able to control the arm (50) between its straight position and its oblique position.

6. Conveyor (20) according to Claim 5, characterized in that the actuator is able to be actuated by an actuating member carried by one of the adjacent shuttles (24).

7. Conveyor (20) according to Claim 6, characterized in that said actuating member consists of a pusher able to come into contact with a pivoting mechanism of an adjacent shuttle (24) in order to control the pivoting of the arm (50).

8. Conveyor (20) according to Claim 7, characterized in that said pivoting mechanism is a cam device.

9. Conveyor (20) according to Claim 7, characterized in that said pivoting mechanism is a meshing device.