Method for guiding and straightening preforms in the gap of a preform alignment and straightening device and related alignment and straightening device

Abstract

The invention relates to a method for guiding preforms (10) in a preform alignment and straightening device (18), and also to such an alignment and straightening device (18), which comprises: a turntable (24); a fixed track (36), the outer support surface (37) of which extends at the same height as the inner support surface (29) of the turntable (24); a peripheral gap (34) radially defined between the turntable (24) and the track (36), a hoop (16) being held jointly by the inner support surface (29) and the outer support surface (37); and is characterized in that the preform (10) is guided in the gap (34) by limiting the radial movement of the preform (10) in two directions by contact between the peripheral edge (42) of the hoop (16) and the stop surfaces (38, 40).

Description

Technical Field

[0001] The invention relates to a method for guiding a straightened axisymmetric preform in a preform alignment and straightening device, the preform comprising:

[0002] - a supporting hoop, delimited radially outwards by the rim, the hoop having an external diameter known as the hoop diameter;

[0003] - a body having a maximum outer diameter, called the body diameter, which is smaller than the diameter of the hoop;

[0004] The alignment and straightening device has:

[0005] - a horizontal circular turntable rotating about a vertical axis for driving the preforms from upstream to downstream;

[0006] - a fixed rail, the upper outer bearing surface of which extends at the same height as the upper inner bearing surface of the turntable, the rail forming an arc centered on the axis of rotation of the turntable;

[0007] - a peripheral gap defined radially between the outer edge of the turntable and the track, the peripheral gap having a constant radial width between the diameter of the body and the diameter of the hoop so as to allow straightening of the preform by passage of the body through the peripheral gap, the hoop being supported by both the upper inner and outer supporting surfaces. Background Art

[0008] The method is intended to be implemented in a preform alignment and straightening device, which is part of a system for producing containers from thermoplastic material, particularly PET, by forming preforms, particularly by blow molding or stretch blow molding. This system allows the production of containers in very large batches at very high production rates, for example, exceeding 85,000 bottles per hour.

[0009] According to a known technique, such containers are produced in two main steps. In the first step, a PET preform is injection-molded or injection-compression-molded. This preform has a substantially tubular body that is closed at one of its axial ends and open at the opposite end by a neck. From this injection-molding operation, the neck assumes the final shape of the container neck.

[0010] There are plants in which the preforms, once injection-molded, are conveyed directly to a forming station, each preform being conveyed individually.

[0011] However, in many cases, preforms are injection molded at a first location and then blow-molded into the final container shape at a second location using specialized manufacturing equipment. This technique allows blow molding to be performed as close as possible to the bottling site, while injection molding can be performed anywhere. While small preforms are easier and less expensive to transport, blown containers are often very large, making transportation uneconomical.

[0012] In the case where the injection molding station and the molding manufacturing equipment are two completely independent machines, the preforms are generally delivered in bulk. Therefore, the blowing station is equipped with a device for aligning the preforms into a row and straightening the preforms. The present invention relates to such a device.

[0013] Figures 1 to 3 1 shows a non-limiting example of preforms 10A, 10B, 10C that can be loaded by an alignment and straightening device.

[0014] First, the common features of the preforms 10A, 10B, and 10C are described. The preforms 10A, 10B, and 10C are made of thermoplastic material, and in this case, PET material. Typically, they are injection molded. The preforms have a Figures 1 to 3 The main axis A is shown vertically, which is a substantially axisymmetric shape.

[0015] The preform has a main body 12 of elongated tubular shape along a main axis A, with a closed axial end and at its opposite end, such as Figures 1 to 3 The upper part is shown with an axially open neck 14 .

[0016] Thus, the preform 10A, 10B, 10C has an annular hoop 16 that projects radially relative to the rest of the body 12. The hoop 16 is delimited radially outwardly by an edge 42. The hoop 16 is arranged above the center of gravity G of the preform 10A, 10B, 10C. The expression "annular" means that the hoop 16 surrounds the preform 10A, 10B, 10C continuously or discontinuously.

[0017] When the hoop 16 is discontinuous, it is formed, for example, by a plurality of separate sectors which constitute a circle around the preform but which are close enough to enable the preform 10A, 10B, 10C to be supported by the lower surface of its hoop 16 on two diametrically opposed supports, whatever the position of the preform 10A, 10B, 10C about its main axis A.

[0018] exist Figures 1 to 3 In the embodiment shown, a collar 16 is disposed at the junction between the base of the neck 14 and the body 12 .

[0019] In a variant not shown, the collar could be arranged elsewhere than at the base of the neck, for example at the mouth.

[0020] According to another variant that is not shown, the hoop is attached to the preform, for example by means of a plug.

[0021] Hoop diameter D1 is defined below as the outer diameter corresponding to hoop 16. Body diameter D2 is also defined as the maximum outer diameter corresponding to body 12. Body diameter D2 is smaller than hoop diameter D1.

[0022] The neck 14 has its final shape, while the body 12 is intended to be stretched during a subsequent forming operation to form the body of the finished container.

[0023] In addition, the weight of the body 12 of the preform 10A, 10B, 10C used is greater than the weight of the neck 14 including the weight of the hoop 16. Therefore, the center of gravity G of the preform 10A, 10B is located below the hoop 16, as shown in FIG. Figure 1 and 2 Thus, the preform 10, supported by its hoop 16 on two diametrically opposed supports, is naturally oriented by gravity with the neck 14 at the top.

[0024] A aligning and straightening device with a centrifugal drum has been proposed. Preforms are randomly thrown onto a turntable forming the base of the centrifugal drum. Centrifugal force then propels the preforms against the peripheral railings. A radially defined peripheral gap between the fixed rails and the peripheral edge of the turntable allows the main body 12 of the preform to pass through, while the preform is supported by its collar 16. In practice, the width of the radial gap lies between the collar diameter D1 and the main body diameter D2. Consequently, the preforms are aligned around the periphery of the centrifugal drum, with their main axes oriented essentially vertically under the influence of gravity.

[0025] The preforms thus straightened and aligned are then conveyed in a row toward the tangential outlet of the centrifugal drum under the action of the rotary motion of the turntable.

[0026] As is known per se, the preforms 10A, 10B are received in the radial clearance with a radial play limited in a first direction by the contact of the section of the body 12 just below the hoop 16 with the edge of the turntable and in a second direction by the contact of said section with the fixed rail.

[0027] exist Figure 1 and 2In both preform geometries shown, 10A and 10B, the body 12 has a body diameter D2 at the junction with the hoop 16. The body 12 of the preform 10A has a substantially constant cross-section corresponding to the body diameter D2 over its entire length, while the diameter of the body 12 of the preform 10B decreases as it approaches its closed lower end. This geometry ensures that the hoop 16 is always supported by both the turntable and the fixed rails with sufficient support surface, thereby preventing the preform from falling entirely through the gap and onto the bottom of the turntable.

[0028] like Figure 3 As shown, some preforms 10C have a slightly different geometry than Figure 1 and 2 The geometry of the preforms 10A, 10B shown. This relates, for example, to a preform 10C for producing a container of large volume, for example greater than 1.5 liters. The preform 10C has the same features as the preforms 10A, 10B described above, except for the shape of the body 12.

[0029] In fact, for this preform 10C, the diameter D3 of the body 12 at the junction with the hoop 16, referred to as the "neck diameter D3", is smaller than the body diameter D2. This geometry makes it possible to distribute the material more suitably for forming large-volume containers. Of course, in order to enable the hoop 16 to perform its supporting function, the hoop diameter D1 remains larger than the body diameter D2.

[0030] However, to allow the body 12 to pass through the gap, the width of the gap must be greater than the body diameter D2 of the preform 10C. However, the neck diameter D3 of the section of the body 12 just below the hoop 16 is much smaller than the gap width. Consequently, the radial play of the preform 10C in the gap may sometimes be so great that, when the preform rests on the turntable, or the corresponding track, the hoop 16 no longer provides sufficient support from the track, or the corresponding rail. The preform 10C is then likely to flip over, become stuck, or even pass entirely through the gap. Summary of the Invention

[0031] The invention relates to a method for guiding straightened axisymmetric preforms in a preform alignment and straightening device.

[0032] The preform has:

[0033] - a supporting hoop, delimited radially outwards by the rim, the hoop having an external diameter known as the hoop diameter;

[0034] - a body having a maximum outer diameter, called the body diameter, which is smaller than the diameter of the hoop;

[0035] The preform alignment and straightening device has:

[0036] - a horizontal circular turntable rotating about a vertical axis for driving the preforms from upstream to downstream;

[0037] - a fixed rail, the upper outer bearing surface of which extends at the same height as the upper inner bearing surface of the turntable, the rail forming an arc centered on the axis of rotation of the turntable;

[0038] - a peripheral gap defined radially between the outer edge of the turntable and the track, the peripheral gap having a constant radial width between the diameter of the body and the diameter of the hoop so as to allow straightening of the preform by passage of the body through the peripheral gap, the hoop being supported jointly by the upper inner and outer support surfaces;

[0039] Characterized in that the preform is guided in the peripheral gap by limiting the radial movement of the preform along the peripheral gap in two directions by contact between the edge of the periphery of the hoop and the inner stop surface inwards and by contact between the edge of the periphery of the hoop and the outer stop surface in outwards.

[0040] The present invention also relates to a preform alignment and straightening device for carrying out the method according to the present invention, said preform alignment and straightening device comprising a centrifugal drum having:

[0041] - a horizontal circular turntable rotating about a vertical axis for driving the preforms from upstream to downstream;

[0042] - an angular sector of the centrifugal drum, in which the centrifugal drum has a peripheral gap defined between the fixed rails and the outer edge of the turntable, the peripheral gap being intended to allow the body of the preform to be tilted below the height of the turntable, the hoop of the preform being intended to be supported jointly by the upper inner supporting surface of the turntable and the upper outer supporting surface of the rails extending at the same height;

[0043] It is characterized in that the turntable has an inner stop surface, which extends upward from the upper inner support surface and faces outward; and the rail has an outer stop surface, which extends upward from the upper outer support surface of the rail and is arranged facing the inner stop surface.

[0044] According to further features of the device implemented according to the teaching of the invention:

[0045] - the inner stop surface is part of the annular shoulder surface between the central portion of the upper surface of the turntable and an upper inner support surface of the turntable, the upper inner support surface being arranged below the level of the central portion;

[0046] - the annular shoulder surface of the turntable has a bevel connecting the inner stop surface with the central portion of the upper surface of the turntable;

[0047] - The second outer stop surface of the rail is extended upward by the inclined surface;

[0048] the turntable comprises a lower peripheral inner guide extending below the upper inner support surface, the lower peripheral inner guide being intended to constrain the hoop of the preform travelling in the peripheral gap to be raised and / or turned relative to the upper inner support surface by contact between the body of the preform and the lower peripheral inner guide;

[0049] the fixed rail has a lower peripheral outer guide for limiting the lifting and / or turning of the hoop of the preform travelling in the peripheral gap relative to the upper outer support surface, through contact between the body of the preform and the lower peripheral outer guide;

[0050] - the upper inner bearing surface and the annular shoulder surface are carried by removable parts to enable the turntable to be adapted to preforms of different sizes;

[0051] The fixed rails are removably mounted to enable the turntable to be adapted to preforms of different sizes. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Other features and advantages of the present invention will become apparent from reading the following detailed description which will be given with reference to the accompanying drawings, in which:

[0053] Figure 1 is a front view showing a preform of a first geometry suitable for fitting Figure 4 The device is used, where the axis of the preform is oriented vertically;

[0054] Figure 2 is a front view showing a second geometric shape of the preform, which is suitable for fitting Figure 4 The device is used, where the axis of the preform is oriented vertically;

[0055] Figure 3 is a front view showing a third geometric shape of the preform, which is suitable for fitting Figure 4 The device is used, where the axis of the preform is oriented vertically;

[0056] Figure 4 is a perspective view schematically showing a preform alignment and straightening device having a centrifugal drum;

[0057] Figure 5 is a top view showing Figure 4 The centrifuge bowl shown;

[0058] Figure 6 yes Figure 4 A radial cross-sectional view of the aligned angle sector of the centrifuge bowl showing the turntable and peripheral railings of the centrifuge bowl and the aligned preforms;

[0059] Figure 7 is a perspective view showing Figure 4The discharge device of the device shown;

[0060] Figure 8 is a top view showing a portion of the alignment sector of the centrifuge drum and the different stages of the path of the preforms discharged into the centrifuge drum;

[0061] Figure 9 yes Figure 4 A radial cross-sectional view of the straightening angle sector of the centrifuge drum, showing the turntable and peripheral railings of the centrifuge drum and the aligned and straightened preforms;

[0062] Figure 10 It is a schematic diagram along the radial direction, showing Figure 4 Preforms aligned along rails in the alignment angle sector of the centrifuge bowl shown;

[0063] Figure 11 yes Figure 10 A top view of

[0064] Figure 12 Similar to Figure 10 , shown in Figure 4 The straightening angle sector of the centrifugal drum shown in the figure begins to straighten. Figure 10 preforms;

[0065] Figure 13 yes Figure 12 A top view of

[0066] Figure 14 Similar to Figure 12 , shown in Figure 4 The straightened angle sector of the centrifugal drum shown has been straightened Figure 12 preforms;

[0067] Figure 15 yes Figure 14 A top view of

[0068] Figure 16 Similar to Figure 9 , showing the preform hoop resting against the outer stop surface of the track. DETAILED DESCRIPTION

[0069] In the following description, components having the same structure or similar function will be denoted by the same reference numerals.

[0070] In the following, without limitation, for each preform present in the centrifugal drum of the alignment and straightening device, the following local orientation is adopted:

[0071] - radial direction R, oriented from the inside to the outside from the axis of rotation B of the turntable 24;

[0072] - a tangential direction T, perpendicular to the radial direction R, extending parallel to the plane of the turntable 24 and oriented from upstream to downstream along the direction of rotation of the turntable 24;

[0073] A vertical direction V, parallel to the axis of rotation B of the turntable 24 , oriented from bottom to top, in the direction opposite to the Earth's gravity.

[0074] Figure 4 The aligning and straightening device 18 is shown for aligning and straightening the preforms 10A, 10B, 10C as described above, and is used to form a component of a manufacturing device (not shown) for manufacturing containers made of thermoplastic material by forming, especially by blow molding or stretch blow molding, using the preforms 10A, 10B, 10C. The aligning and straightening device 18 is suitable for Figures 1 to 3 For all of the illustrated preforms 10A, 10B, 10C, a general reference numeral “preform 10 ” will be used to refer to any one of the preforms 10A, 10B, 10C to simplify reference to the drawings.

[0075] This involves an alignment and straightening device 18 as described in document WO 2016 / 166459 A1 or US 2018 / 0086570 A1.

[0076] As described later, aligning and straightening device 18 can process several batches of identical preforms 10, and the specifications of preforms 10 can change with batch. Therefore, when changing the specifications of preforms 10, different adjustments can be made on aligning and straightening device 18.

[0077] Back to Figure 4 The alignment and straightening device 18 mainly comprises a centrifugal drum 20 and an output conveyor 22 for outputting a row of straightened preforms 10. The output conveyor 22 is used to transport the straightened preforms 10 so as to distribute them one by one to the next processing station (not shown) of the manufacturing equipment, such as a loading device of a heating furnace for preforms 10, in which each preform 10 is loaded individually.

[0078] The centrifugal bowl 20 has a horizontal circular turntable 24 that rotates about a central vertical axis B. Thus, the turntable 24 has Figure 6 The upper surface 27 of the turntable 24 defines vertically downwardly the inner volume of the centrifuge bowl 20. The turntable 24 thus forms the bottom of the centrifuge bowl 20. The upper surface 27 of the turntable 24 has a peripheral annular band which serves to form an inner bearing surface 29 for the hoop 16 of the preform 10, as will be described later.

[0079] The outer diameter of the turret 24 is much larger than the size of the preform 10 .

[0080] The turntable 24 can be driven to rotate at a constant speed, here in a clockwise direction in a top view, for example, by a motor (not shown) arranged below the turntable 24. The speed is controlled, for example, so that the outer edge 25 of the turntable 24 moves at between 2 m / s and 3 m / s.

[0081] The turntable 24 is here carried by a support platform 26 fixed to the ground. The support platform 26 has legs that are advantageously height-adjustable to allow the stability of the turntable 24 to be adjusted.

[0082] The internal volume of the centrifuge drum 20 is delimited radially outward by a fixed peripheral railing 28, which is fixed to the support table 26. In particular, the first function of the railing 28 is to retain the preforms 10 ejected outward by the centrifugal force generated by the rotation of the turntable 24, and the second function is to guide the preforms 10 as far as the outlet channel 32 of the centrifuge drum 20 arranged in the railing 28, in particular as shown in FIG. Figure 7 shown.

[0083] The preforms 10 are intended to be discharged in bulk onto the turntable 24 by means of a fixed discharger 30. Here, the discharger 30 is arranged in the center of the turntable 24. The discharger 30 is designed to discharge the bulk preforms 10 radially in the direction of the receiving portion 28A of the rail 28. Here, the discharger 30 is in the form of a slide to which the preforms 10 are fed from above by means of an elevator belt (not shown).

[0084] like Figure 5 As shown, for illustrative purposes, the centrifuge bowl 20 is divided into three angular sectors fixed relative to the support table 26.

[0085] A first alignment sector 20A for aligning the preforms 10 extends facing the output opening of the discharger 30. The alignment sector 20A includes a receiving portion 28A for the rail 28.

[0086] The second straightening angular sector 20B, for straightening the aligned preforms 10, is arranged directly downstream of the first straightening angular sector 20A. In a non-limiting manner, it extends here generally over 180°.

[0087] A third angular output sector 20C for outputting correctly positioned preforms 10 is arranged directly downstream of the second straightening angular sector 20B and directly upstream of the first row of angular sectors 20A. At the downstream end of this angular output sector 20C, an output channel 32 for preforms 10 opens in the railing 28, allowing the correctly positioned preforms 10 to be guided toward the conveyor 22.

[0088] The naming of each of these angular sectors 20A, 20B, 20C provides an indication as to its function.

[0089] A working gap is provided between the rails 28 and the turntable 24 over the entire periphery of the first row of angular sectors 20A. This gap allows the turntable 24 to rotate, but is small enough to allow the rails 28 to hold the entire preform 10 within the centrifuge bowl 20.

[0090] like Figure 6 As shown, in this row of angular sectors 20A, a railing 28 extends vertically above the turntable 24 , so that the outer edge 25 of the turntable 24 is arranged outside the centrifuge drum 20 .

[0091] During the operation of the aligning and straightening device 18, Figure 7 and 8 As shown, during the first discharge process, the preforms 10 randomly discharged by the discharger 30 are radially projected against the railing 28 under the combined action of the radial sliding speed when discharged from the discharger 30 and the centrifugal force generated by the rotation of the turntable 24. At the same time, the turntable 24 also begins to drive the preforms 10 tangentially downstream during rotation.

[0092] During the second alignment process, the preform 10 is held in the centrifugal drum 20 by the railing 28, and then the preform 10 gradually loses its speed in the radial direction after bouncing once or several times on the railing 28. The preform is then always held radially against the railing by centrifugal force. Figure 8 3 shows the path followed by the same preform 10 from the discharge device 30 to its stable position against the rail 28. The preform 10 is then driven by the turntable 24 along the rail 28 and moves completely tangentially in the clockwise direction.

[0093] In this configuration, the preform 10 is naturally in the most stable position, in which its main axis A is oriented in a direction tangential to the turntable 24 .

[0094] As a result, the majority of preforms 10 present in the alignment angular sector 20A of the centrifuge bowl 20 are tangentially aligned against the rails 28, with their main axes A oriented substantially tangentially to their direction of movement. The tangential spacing between two consecutive aligned preforms 10 is random, since the turntable 24 is completely flat and lacks recesses for positioning the preforms 10. Consequently, the preforms 10 can contact their ends under the action of centrifugal force, forcing the preforms 10 to slide relative to one another. Consequently, the preforms 10 optimally occupy the entire circumferential length of the centrifuge bowl 20.

[0095] The preforms 10 are held on the turntable 24, which keeps them radially against the rails 28. Thus, the preforms 10 are stably guided by the rails 28 during their movement around the centrifuge drum 20.

[0096] At this stage, the preform 10 is randomly oriented with the neck 14 facing upstream or downstream without affecting the subsequent process. The preform 10 thus aligned continues its peripheral movement in the straightening angle sector 20B.

[0097] like Figure 9 As shown, in the second straightened angle sector 20B of the centrifuge bowl 20, the centrifuge bowl 20 has a peripheral gap 34 formed by the radial spacing of the rails 28 relative to the outer edge 25 of the turntable 24. The radial width of the gap 34 is between the body diameter D2 and the hoop diameter D1. The gap 34 extends to the outlet channel 32 of the preforms 10.

[0098] At least entirely along the second straightening angle sector 20B, the rail 28 has a support rail 36 for supporting the hoop 16. The rail 36 extends radially inwardly in a convex manner. The upper surface of the rail 36 forms an outer support surface 37 for supporting the hoop 16 of the preform 10, as will be described later. The outer support surface 37 of the rail 36 extends at the same height as the inner support surface 29 of the turntable 24.

[0099] The gap 34 is thus delimited inwardly by the outer edge 25 of the inner bearing surface 29 of the turntable 24 and outwardly by the inner edge of the outer bearing surface 37 of the track 36. The track 36 forms an arc of a circle centered on the axis of rotation B of the turntable 24. Here, the track 36 is extended to the outlet channel 32.

[0100] Thus, the preform 10 can be held by its collar 16, which bears at two diametrically opposed points of support, on the one hand, on the inner support surface 29 of the turntable 24, and on the other hand, on the outer support surface 37 of the rail 36, the body 12 of the preform 10 passing through said gap 34 below the level of the turntable 24. These two points of support are radially aligned. The rail 36 allows the preform 10 to be held stably.

[0101] Therefore, in the third straightening process, if Figure 10 and 11 As shown, in the second step, the preforms 12 aligned arrive from the first alignment sector 20A and are aligned in a lying position along the rail 28 in a row with the main axis A of the preforms oriented tangentially. The aligned preforms 10 are randomly arranged with the neck 14 facing upstream or the neck 14 facing downstream, without affecting their straightening.

[0102] When the main body 12 of each preform 10 reaches the top of the gap 34, the main body 12 begins to fall, as shown in FIG. Figure 12 and 13As shown, the preform 10 is thereby turned over about a radial axis passing through the support point of the hoop 16 of the preform 10. The turning is continued until the main axis A of the preform 10 is vertical, if necessary after several turns about the radial axis. The preform 10 is now held together by its hoop 16, by the outer support surface 37 of the rail 36 and by the inner support surface 29 of the turntable 24, as shown in FIG. Figure 14 and 15 Thus, the preform 10 is straightened with the neck 14 at the top. The preform 10 thus correctly positioned is guided along the gap 34 in the direction of the output channel 32 by means which will be described in more detail below.

[0103] During the tilting process, the main axis A of the preform 10 remains in a vertical plane tangential to the displacement. Since the main axis A tilts in the direction of movement of the preform 10, the hoop 16 of each preform 10 always maintains contact with the turntable 24 at its two support points, on the one hand, and with the rails 36 at the other. Thus, each preform 10 is stably and effectively supported during its straightening.

[0104] like Figure 13 As shown, the transition zone is located upstream of the straightening angle sector 20B. In this transition zone, the gap 34 gradually expands until it reaches its final width. To achieve this, the rails 36 of the rails 28 gradually move radially away from the axis of rotation B of the turntable 24. This ensures that the aligned preforms 10 remain in contact with the rails 28 at all times due to centrifugal force. Thus, the preforms 10 are stably guided in the aligned position even during straightening. The width of the gap 34 then remains constant, between the body diameter D2 and the hoop diameter D1, all the way to the output channel 32 of the alignment and straightening device 18.

[0105] The preforms 10 thus aligned and straightened are driven in rotation about their main axis A by friction against the outer edge 25 of the turntable 24 . The straightened preforms 10 are moved around the periphery of the centrifuge drum 20 in the direction of rotation of the turntable 24 by running on rails 36 .

[0106] The straightened preforms 10 are thus transported to the third output angular sector 20C. The third output angular sector 20C includes a device for ensuring that only correctly aligned and straightened preforms 10 reach the output channel 32. Such a device is not the subject of the present invention and will not be described in detail below. For more details, please refer to the aforementioned literature.

[0107] In a known manner, the preform 10 is guided in the recess 34 by:

[0108] - limiting the radially inward movement of the preform 10 along the gap 34 by contact between the preform 10 and the inner stop surface 38 of the turret 24, and

[0109] The preform 10 is limited in its radially outward movement along the interspace 34 by its contact with the outer stop surface 40 of the rail.

[0110] However, it is important that even when the preform 10 contacts the stop surface 38, 40 of one of the inner and outer support surfaces 29, 37 located on the first side of the gap 34, the hoop 16 is always supported on the outer or inner support surface 37, 29 located on the opposite side of the gap 34 with sufficient support surface.

[0111] To allow any type of preform 10, in particular Figure 3 The present invention provides for guiding a preform 10C of the type shown:

[0112] - limiting the radially inward movement of the preform 10 in the void 34 by contact between the outer peripheral edge 42 of the hoop 16 and the inner stop surface 38, and

[0113] The preform 10 is limited in its radially outward movement in the interspace 34 by the contact of the outer peripheral edge 42 of the hoop 16 with the outer stop surface 40 .

[0114] Therefore, the radial play of the preform 10 becomes independent of the neck-down diameter D3 of the body 12. The radial play is determined only by the hoop diameter D1.

[0115] like Figure 9 As detailed in FIG, in order to limit the radially inward movement of the straightened preform 10 in the gap 34, the turntable 24 therefore has an inner stop surface 38 extending upward from the inner support surface 29. The inner stop surface 38 faces radially outward. It has an annular shape centered on the rotation axis B of the turntable 24. Thus, the inner support surface 29 is radially delimited by the outer edge 25 of the turntable 24 and by the inner stop surface 38.

[0116] The inner stop surface 38 is part of the annular shoulder surface 44 between the circular central portion 46 of the upper surface of the turret 24 and the inner support surface 29. The inner support surface 29 is stepped relative to the central portion 46 so that the inner support surface 29 is positioned below the level of the central portion 46. This height difference is approximately a few millimeters. For example, the height of the inner stop surface 38 generally corresponds to the thickness of the hoop 16 of the preform 10.

[0117] To limit the radially outward movement of the straightened preform 10 in the gap 34, the rail 36 has an outer stop surface 40 that extends upward orthogonally from the outer support surface 37 of the rail. The outer stop surface 40 is arranged radially facing the inner stop surface 38. The outer support surface 37 is thus radially delimited by the inner free edge of the rail 36 and by the outer stop surface 40.

[0118] The two stop surfaces 38, 40 radially delimit a guide 48 for the hoop 16, which extends along the interspace 34. The width l of the guide 48 is defined as corresponding to the radial distance between the inner stop surface 38 and the outer stop surface 40. Except for the transition region, the width l of the guide 48 remains constant along the entire interspace 34. The width l is equal to the sum of the hoop diameter D1 and the radial gap j, thereby ensuring that the hoop 16 rests on the inner and outer support surfaces 29, 37 with sufficient support surface, regardless of the radial position of the straightened preform 10 between the two stop surfaces 38, 40.

[0119] The radial width of the inner support surface 29 of the turntable 24 is greater than the gap j to ensure sufficient support for the hoop 16 even if Figure 16 The same is true when the edge 42 of the hoop 16 abuts against the outer stop surface 40. The radial width of the inner support surface 29 is also smaller than the difference between the hoop diameter D1 and the neck lower diameter D3, in the case of a preform 10 having a geometry similar to that of the hoop 16. Figure 3 This is particularly true with respect to the geometry of the illustrated preform 10C.

[0120] Likewise, the radial width of the outer support surface 37 of the track 36 is greater than the gap j to ensure adequate support for the hoop 16 even when the edge 42 of the hoop 16 abuts against the inner stop surface 38. The radial width of the outer support surface 37 is also less than the difference between the hoop diameter D1 and the neck lower diameter D3, which is similar to the preform 10 geometry. Figure 3 This is particularly true with respect to the geometry of the illustrated preform 10C.

[0121] exist Figure 9 and 16 In the embodiment shown, the inner support surface 29 of the turntable 24 and the outer support surface 37 of the track 36 have the same width.

[0122] In order to ensure that the hoop 16 of the preform 10 is supported fairly evenly by the inner and outer support surfaces 29, 37 and that the hoop is correctly received in the guide 48, the annular shoulder surface 44 of the turntable 24 has an inclined surface 50 connecting the inner stop surface 38 with the central portion 46 of the turntable 24, and / or the second outer stop surface 40 of the rail is extended upwardly by an inclined surface 53. This allows the hoop 16 to slide between the two stop surfaces under the action of gravity during the straightening of the preform 10 by sliding on the inclined surfaces 50, 53 forming the converging hopper.

[0123] In order to adapt the alignment and straightening device 18 to batches of preforms 10 of different types, in particular batches of preforms 10 having hoops 16 of various sizes, it is advantageous to be able to vary the width l of the guideway 48. In practice, at least one of the rails 36 and the peripheral portion 54 of the turntable 24 is removable.

[0124] For example, the peripheral portion 54 of the turntable 24 having the inner bearing surface 29 and the shoulder surface 44 is formed by detachable attachment parts to enable the turntable 24 to be adapted to preforms 10 of different sizes. The detachable peripheral portion 54 is, for example, composed of a plurality of distinct segments which, when assembled with the turntable 24, form a complete circle.

[0125] According to another example, which can be combined with the embodiment described in the preceding paragraph, the fixed rail 36 is removably mounted under the rail 28 in one or more parts, so as to be able to adapt the turntable 24 to preforms 10 of different sizes.

[0126] In order to limit the lateral tilting of the straightened preform 10 engaged in the recess 34 and thus to limit the risk of the hoop 16 being lifted on one side of the recess 34 and coming to bear on the other side, with the result that the preform accidentally escapes from its guide 48, the turntable 24 can be provided with a lower peripheral inner guide 56 extending below the inner support surface 29. The lifting is particularly limited so that the hoop 16 cannot be lifted from the inner support surface 29 by tilting to a distance greater than the height of the corresponding inner stop surface 38. The inner guide 56 serves to limit the lifting of the hoop 16 from the inner support surface 29 by contact between the body 12 of the preform 10 and the inner guide 56.

[0127] Therefore, for the same reason, it can also be provided that the fixed rail 36 has a lower peripheral outer guide 58, which extends below the outer support surface 37 of the rail 36. The outer guide 58 serves to limit the lifting of the hoop 16 from the outer support surface 37 of the rail 36 by contact between the body 12 of the preform 10 and the outer guide 58. The lifting is more particularly limited so that the distance by which the hoop 16 is lifted from the outer support surface 37 by tilting cannot be greater than the height of the corresponding outer stop surface 40.

[0128] Advantageously, the alignment and straightening device 18 with the recess 34 and the guide for the hoop 16 according to the teachings of the invention ensures that the straightened preforms 10 are well supported in the recess 34 regardless of their neck diameter D3.

Claims

1. A method for guiding a straightened axisymmetric preform (10) in a preform alignment and straightening device (18), the preform (10) having: - a supporting hoop (16), delimited radially outwards by the edge (42), the hoop (16) having an external diameter known as the hoop diameter (Dl); - a body (12) having a maximum outer diameter, called the body diameter (D2), which is smaller than the hoop diameter (D1); The preform aligning and straightening device (18) has: - a horizontal circular turntable (24) rotating about a vertical axis for driving the preforms (10) from upstream to downstream; - a fixed rail (36), the upper outer bearing surface (37) of which extends at the same height as the upper inner bearing surface (29) of the turntable (24), the rail (36) forming an arc centered on the axis of rotation (B) of the turntable (24); - a peripheral gap (34) defined radially between the outer edge (25) of the turntable (24) and the track (36), the peripheral gap (34) having a constant radial width between the diameter of the body (D2) and the diameter of the hoop (D1) so as to allow the preform (10) to be straightened by the passage of the body (12) through the peripheral gap (34), the hoop (16) being retained by the upper inner support surface (29) and the upper outer support surface (37); It is characterized by: The guidance of the preform (10) in the peripheral gap (34) consists in limiting the radial movement of the preform (10) along the peripheral gap (34) in two directions by the inward contact between the peripheral edge (42) of the hoop (16) and the inner stop surface (38), and by the outward contact between the peripheral edge (42) of the hoop (16) and the outer stop surface (40).

2. A preform (10) alignment and straightening device (18) for implementing the method according to claim 1, wherein the preform (10) alignment and straightening device (18) comprises a centrifugal drum (20) having: - a horizontal circular turntable (24) rotating about a vertical axis (B) for driving the preforms (10) from upstream to downstream; - an angular sector (20B) of the centrifuge drum, in which the centrifuge drum (20) has a peripheral gap (34) defined between a fixed rail (36) and an outer edge (25) of the turntable (24), the peripheral gap (34) being intended to allow the body (12) of the preform (10) to be tilted below the level of the turntable (24), the hoop (16) of the preform (10) being intended to be held by an upper inner support surface (29) of the turntable (24) and an upper outer support surface (37) of the rail (36) extending at the same level; It is characterized by: The turntable (24) has an inner stop surface (38) extending upward from the upper inner support surface (29) and facing outward; and the track (36) has an outer stop surface (40) extending upward from the upper outer support surface (37) of the track (36) and arranged facing the inner stop surface (38).

3. The preform alignment and straightening device (18) according to claim 2, characterized in that The inner stop surface (38) is part of an annular shoulder surface (44) between a central portion (46) of the upper surface (27) of the turntable and an upper inner support surface (29) of the turntable (24), the upper inner support surface (29) being arranged below the level of the central portion (46).

4. The preform alignment and straightening device (18) according to claim 3, characterized in that The annular shoulder surface (44) of the turntable has a bevel that connects the inner stop surface (38) to the central portion (46) of the upper surface (27) of the turntable (24).

5. The preform alignment and straightening device (18) according to any one of claims 2 to 4, characterized in that The outer stop surface (40) of the track (36) is extended upwardly by the inclined surface.

6. The preform alignment and straightening device (18) according to claim 2, characterized in that The turntable (24) has a lower peripheral inner guide (56) extending below the upper inner support surface (29), the lower peripheral inner guide being used to limit the hoop (16) of the preform (10) traveling in the peripheral gap (34) from being lifted and / or turned relative to the upper inner support surface (29) through contact between the body (12) of the preform (10) and the lower peripheral inner guide (56).

7. The preform alignment and straightening device (18) according to claim 2, characterized in that The fixed track (36) has a lower peripheral outer guide (58) for limiting the lifting and / or turning of the hoop (16) of the preform (10) traveling in the peripheral gap (34) relative to the upper outer support surface (37) through contact between the body (12) of the preform (10) and the lower peripheral outer guide (58).

8. The preform alignment and straightening device (18) according to claim 3, characterized in that The upper inner support surface (29) and the annular shoulder surface (44) are carried by a removable member (54) to enable the turntable (24) to be adapted to preforms of different sizes.

9. The preform alignment and straightening device (18) according to claim 2, characterized in that The fixed rails (36) are removably mounted to enable the turntable (24) to be adapted to preforms of different sizes.

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