Tire building drum provided with integrated attachment means comprising retractable clamping tabs

Abstract

The invention relates to a drum (1) for building tyres, said drum (1) having a central axis (Z1) and having a receiving surface (2) designed to receive at least one constituent element (3) of a tyre, said drum comprising attachment means (5) designed to hold said constituent element (3) of a tyre on said receiving surface (2), the attachment device (5) comprises a base (6), a clamping jaw (7) formed by a leaf spring (40), and an actuating mechanism (10) having an articulated quadrilateral (20) comprising a first arm (26) and a second arm (27) shorter than the first arm (26) for alternately moving the clamping jaw (7) from a rest position (P0) to a working position (P1) in which the clamping jaw (7) is movable between a rest position (P0) and a working position (P1) in which the clamping jaw (7) is movable between a rest position (P0) and a working position (P0) in which the clamping jaw (7) is movable between the rest position (P0) and the working position (P1). The clamping claw (7) exerts a clamping force (Fclamp) on the component element (3) of the tyre.

Description

Technical Field

[0001] The present invention relates to the field of tire building, in particular to pneumatic tires for vehicle wheels.

[0002] More specifically, the invention relates to a drum for forming annular tire components by winding one or more elements in the form of strips on the drum. Background Art

[0003] The invention is particularly applicable in cases where it is desired to form an annular reinforcement (called "wrap") designed to form a strapping in the crown of a tire for a vehicle wheel, by winding a rubber-based strip comprising continuous reinforcing threads parallel to one another and positioned along the length of the strip, on a drum in a plurality of successive helical turns (these turns may, for example, overlap axially or, on the contrary, may be axially juxtaposed without overlapping).

[0004] One of the difficulties with this type of winding operation is holding the leading end of the strip firmly in the desired starting position on the drum so as to allow the strip to be pulled behind it as the drum rotates without the leading end of the strip slipping or falling under tension, gravity or centrifugal force.

[0005] When the rubber constituting the strip has sufficient tack, i.e. sufficient intrinsic adhesion, it is conceivable to attach the front end of the strip to the drum simply by placing it on the surface of said drum. It will be understood that the firmness of this type of attachment depends on the affinity that exists firstly between the material of the rubber-based strip and secondly the surface of the drum. This affinity may vary greatly, depending on whether the surface of the drum on which it is desired to place the constituent elements of the tyre is made of metal and is bare, or, on the contrary, is already coated with the first constituent elements of the tyre forming the first rubber base layer.

[0006] Similarly, when the strip contains metallic reinforcing wires having magnetic sensitivity, magnets may be used to cause the strip to adhere to the drum.

[0007] However, not all strips are sticky or magnetizable.

[0008] Therefore, as disclosed in application WO-2020 / 08069 filed by the applicant, an attachment device has been conceived which uses a retractable needle deployed from the drum so as to protrude from the surface of the drum at an angle relative to said surface of the drum, thereby piercing the strip and thus holding said strip in place.

[0009] While such devices undeniably provide good results, certain disadvantages sometimes occur.

[0010] The first possible disadvantage is the relative fragility of the needle.

[0011] A second possible disadvantage is that the device is difficult to adapt to the various tire builds, since, depending on the tire being built and in particular on the size of said tire, it may be necessary to lay strips of widely varying widths and / or to adopt winding start positions along the axis of the drum that vary widely from one tire model to another or from one component to another. Summary of the invention

[0012] The object of the present invention is therefore to eliminate the above-mentioned drawbacks and to propose a new attachment device capable of temporarily and reversibly retaining the constituent elements of a tyre on a forming support such as a drum, which, while ensuring a firm and reliable retention of the constituent elements of the tyre, is still light, compact and inexpensive and has a good versatility, enabling it to be adapted to a wide variety of tyres and related forming configurations.

[0013] The object of the invention is achieved by a drum for building tyres, said drum having a central axis and a radially outer surface, called "receiving surface", extending along and around said central axis and designed to receive at least one constituent element of said tyre, said drum comprising attachment means designed to retain said constituent element of said tyre on said receiving surface, said drum being characterized in that said attachment means comprise:

[0014] - a base attached to the drum so that the attachment device is supported by said drum;

[0015] - clamping jaws designed to adopt a so-called "working position" in which they bear on a radially external surface of a constituent element of the tyre, while an opposite surface of said constituent element of the tyre forming a radially internal surface bears on a receiving surface, so as to exert on said constituent element of the tyre a radial compression force, called "clamping force", which holds said constituent element of the tyre on said receiving surface;

[0016] - an actuating mechanism supported by the base and connecting the clamping jaws to said base, said actuating mechanism being designed to cause the clamping jaws to alternately perform a first movement, known as an "engagement movement", relative to the base and therefore to the receiving surface, which brings the clamping jaws from a rest position to an operative position, and a second movement, known as a "disengagement movement", which returns the clamping jaws to a rest position by displacing them according to both a radial component, which serves to release the clamping force, and an axial component, which serves to clear the axial area occupied by the constituent elements of the tire on the receiving surface.

[0017] Advantageously, by incorporating the attachment means in the drum so that they are permanently integral with the drum, and more specifically with the receiving surface of the drum, a simple, compact and light structure is obtained which does not, in particular, require the provision of complex equipment, distinct from the drum, in order to bring the attachment means to the receiving surface and to position it relative to it and / or to cause the attachment means and the drum to rotate synchronously.

[0018] Advantageously, the actuation mechanism according to the invention makes it possible to easily clamp the constituent elements of the tire by means of the clamping jaws, which approach the receiving surface during the engagement movement via an approach trajectory including a radial component, and thus the clamping jaws can efficiently and stably press the constituent elements of the tire against the receiving surface of the drum by applying a radial clamping force, and thus the clamping force is substantially oriented in a direction perpendicular to the receiving surface.

[0019] Thus, the clamping jaws can come into contact with a constituent element of the tyre and then intensify the force they exert on said constituent element of the tyre against the receiving surface supporting said constituent element of the tyre until the desired radial clamping force intensity is obtained, without any risk of the constituent element of the tyre slipping on the receiving surface relative to the position that one wishes to assign to said constituent element of the tyre, which position generally corresponds to the starting position of winding. Thus, the attachment device according to the invention makes it possible to reliably and reproducibly clamp and hold one constituent element of the tyre firmly and stably to another constituent element.

[0020] Furthermore, this same actuation mechanism according to the invention makes it possible to precisely define the position and extent of the area covered by the clamping jaws, in particular the area covered axially, when said clamping jaws are in the operative position. In particular, it is thus ensured that the area covered by the clamping jaws when in the operative position is large enough to hold the constituent elements of the tyre securely on the receiving surface, while being small enough that the clamping jaws do not interfere with the laying trajectory, in particular the spiral laying trajectory in this case, followed by said constituent elements of the tyre when they are wound on the drum.

[0021] In other words, the attachment means, and more particularly the clamping jaws, are advantageously configured so as not to hinder the laying of the constituent elements of the tyre, and in particular not to wedge under one or more thicknesses of said constituent elements of the tyre thus laid.

[0022] Finally, the actuation mechanism according to the invention advantageously makes it possible, once the constituent elements of the tyre have been wound on the drum, to first remove the clamping jaws from the receiving surface during a disengaging movement, at least according to a movement component centrifugal radial and therefore substantially perpendicular to the receiving surface, which makes it possible to eliminate the clamping by releasing the radial clamping forces and separating the clamping jaws from the constituent elements of the tyre, while avoiding damaging the constituent elements of the tyre or accidentally causing them to slide on the receiving surface.

[0023] Furthermore, this same actuation mechanism also enables the axial retraction of the clamping jaws, advantageously without rubbing against the constituent elements of the tyre, placing them in a rest position outside the receiving surface area axially occupied by the constituent elements of the tyre situated on the drum.

[0024] The receiving surface area thus detached (and therefore the constituent elements of the tyre situated on the drum) is thus easily accessible, in order either to lay and wind a second constituent element of the tyre on said constituent element of the tyre, in order to continue the ongoing forming cycle for the purpose of producing a layered tyre structure, or to remove the annular unit formed by said constituent elements of the tyre situated on the drum and thus empty the receiving surface of the drum in order to engage with a constituent element of a subsequent tyre, without being hindered by the clamping jaws, and thus to start a new forming cycle.

[0025] The attachment device according to the invention therefore does not hinder either the laying and initial attachment of the constituent elements of the tyre on the drum, nor the winding of said constituent elements of the tyre on the drum, nor the removal of said constituent elements of the tyre after winding.

[0026] Furthermore, as will be described below, the attachment device according to the invention is easily reconfigurable and in particular is able to adjust the axial dimensions of said clamping jaws from the desired starting position, according to the dimensions of the constituent elements of the tire, and / or to adjust the axial and / or radial travel of the clamping jaws, as well as adjusting, if applicable, the degree of overlap that is desired to be obtained between successive turns of said constituent elements of the tire, by simply replacing the clamping jaws. The attachment device thus has a great adaptability to highly variable structures and dimensions of tires. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Other objects, features and advantages of the present invention will become more detailed upon reading the following description and the accompanying drawings, which are provided by way of non-limiting illustration only, in which:

[0028] Figure 1A A general perspective view of a drum according to the invention is shown, the drum being provided with an attachment device incorporated in one of the drum pieces constituting the drum, the clamping jaws of the attachment device being in an operative position and holding the front end of the strip pressed against a receiving surface of the drum, which in this case corresponds to the radially outer surface of the drum piece.

[0029] Figure 1B A detailed inset view of FIG. 1 in the area of ​​the drum supporting the attachment means.

[0030] Figure 2 for Figure 1A and Figure 1BDetailed perspective view of the drum blade of the central drum, the attachment means of the drum exerting a substantially radial clamping force on the ends of the strips via the clamping jaws placed in the working position.

[0031] Figure 3 for Figure 2 Detailed view with cutouts of the drum showing the actuation mechanism of the attachment device, which in this case comprises an articulated quadrilateral supporting the clamping jaws, wherein the clamping jaws are in the working position.

[0032] Figure 4 for Figure 2 and Figure 3 Detailed view of the drum with a cutout showing the actuation mechanism of the attachment device with the clamping jaws in the rest position.

[0033] Figure 5 , Figure 6 , Figure 7 and Figure 8 The attachment device and its actuation mechanism are shown in detail in different successive stages of the detachment movement according to a cross-sectional view on a radial plane containing the central axis of the drum, wherein: Figure 5 Corresponding to the working position, Figure 8 Corresponding to the rest position, Figure 6 and Figure 7 Corresponding to the first intermediate position and the second intermediate position. DETAILED DESCRIPTION

[0034] The invention relates to a drum 1 for building tyres.

[0035] Preferably, the tire can be a tire designed to equip a vehicle wheel, more specifically a pneumatic tire. However, in a non-limiting manner, the present invention can also be used to mold other types of tires, such as tracks, belts or conveyor belts.

[0036] from Figure 1A As can be clearly seen therein, the drum 1 has a centre axis Z1 and has an outer radial surface 2, called “receiving surface” 2, extending along and around said centre axis Z1 and designed to receive at least one constituent element 3 of said tyre.

[0037] The receiving surface 2 has essentially a form of revolution around the central axis Z1, preferably a right cylindrical form (whose generatrix is ​​a straight line parallel to the central axis Z1), or even more preferably a slightly curved form, barrel-shaped (whose generatrix is ​​curved and concave relative to the central axis Z1 so as to bend towards the outside).

[0038] “Axial” means a direction parallel to a relevant axis, in this case more specifically parallel to the central axis Z1 of the drum.

[0039] “Radial” means a direction perpendicular to the relevant axis, in this case more specifically the direction Y1 perpendicular to the centre axis Z1 of the drum, or, if applicable, equivalently to the receiving surface 2 at the relevant point.

[0040] By "circumferential direction" is meant an orthogonal radial direction, i.e. a direction which is perpendicular to a radial plane containing the relevant axis at the relevant point and passes through said relevant point. More specifically, here we will consider a circumferential direction X1 which is perpendicular to a radial plane containing the central axis Z1 of the drum 1 at the relevant point and passes through the relevant point. The circumferential direction is therefore contained in a plane perpendicular to the relevant axis and, in this plane perpendicular to the relevant axis, is perpendicular to the radius connecting said relevant axis to the relevant point.

[0041] The constituent elements of the tyre 3 are preferably strips 4, which, when they reach the receiving surface 2, have a length extending substantially along a circumferential direction X1 tangential to the receiving surface 2, a width W3 extending substantially along an axial direction defined by the central axis Z1 of the drum, and a thickness E3 extending along a radial direction Y1.

[0042] The constituent elements of the tyre 3, and more particularly said strips 4, preferably comprise reinforcing threads extending continuously in the length direction of said constituent elements of the tyre 3, parallel to each other and to the lateral edges of said constituent elements of the tyre 3. These reinforcing threads serve the purpose of rendering the constituent elements of the tyre 3 almost inextensible under longitudinal traction forces.

[0043] These reinforcing threads may be made of any suitable material, such as metal, polymers (eg aramid), natural textile fibers or glass fibers.

[0044] These reinforcing threads may be incorporated in a matrix made of any suitable material.

[0045] In particular, metallic or polymeric reinforcement cords may preferably be embedded in a rubber-based matrix. As a variant, glass fiber reinforcement cords may be embedded in a resin matrix so that the constituent elements of the tire 3 form a glass-resin compound.

[0046] Preferably, the drum 1 is mounted to rotate about its axis Z1, so that rotation of said drum 1 and therefore of its receiving surface 2 makes it possible to wind the constituent elements of the tyre 3 on the receiving surface 2 one or more times about the central axis Z1, thus forming an annular unit together with said constituent elements of the tyre 3.

[0047] The drum 1 comprises attachment means 5 designed to retain the constituent elements of the tyre 3 on the receiving surface 2 .

[0048] The attachment means 5 are designed to ensure a temporary and reversible attachment of the constituent elements of the tyre 3 on the receiving surface 2, in particular at the beginning of the winding operation and more preferably during the entire winding operation. Once the winding operation has been completed, the attachment means 5 are designed to be able to release the constituent elements of the tyre 3 and, more generally, the annular unit that will result from the winding operation.

[0049] In particular, from Figure 1A , Figure 1B and Figure 2 As can be seen in FIG. 5 , the attachment means 5 are more particularly designed to hold the front end 3F of the constituent elements of the tyre 3 in the region of the receiving surface 2 corresponding to the starting position from which it is desired to wind the constituent elements of the tyre 3 on the drum 1 .

[0050] In practice, the aforementioned front end 3F advantageously corresponds to the front end of the strip 4 .

[0051] According to the invention, the attachment device 5 comprises a base 6 attached to the drum 1 such that the attachment device 5 is supported by said drum 1 .

[0052] Advantageously, the attachment means 5 are thus mounted on the drum 1 and are permanently coupled to the receiving surface 2 as long as the base 6 remains attached to the drum 1. The attachment means 5 are therefore spontaneously integral with the movements of the drum 1 and more specifically with the movements of the receiving surface 2, in this case the rotational movement of the receiving surface 2 about the central axis Z1.

[0053] Thus, the attachment device 5 does not require additional equipment different from the drum 1 to orient the attachment device 5 towards the drum 1 , properly position the attachment device 5 relative to the drum and then rotate the attachment device 5 synchronously with the drum 1 about the central axis Z1 .

[0054] The attachment of the base 6 on the drum is advantageously reversible, allowing the attachment means 5 to be removed for maintenance or replacement purposes thereof.

[0055] Such attachment can be achieved, for example, by means of screws.

[0056] In particular, the base 6 enables the attachment device 5 to remain attached to the drum 1 , and therefore coupled to the receiving surface 2 , without interruption from one winding operation of the constituent elements of the tyre 3 to another winding operation of the constituent elements of the tyre 3 .

[0057] Thus, the base 6 keeps the attachment means 5 attached to the same drum 1 while said drum 1 is transferred between a plurality of successive building stations, thereby making it possible to lay a plurality of constituent elements 3 of the same tyre successively on said drum 1, in particular to stack them in successive layers on said drum 1. The base 6 also keeps the attachment means 5 attached to a single drum 1 without interruption during a plurality of successive building cycles, during which said same drum 1 is reused in each building cycle in order to build a plurality of successive different tyres on said drum 1.

[0058] The attachment device 5 also comprises a clamping jaw 7 which is designed to adopt a position P1 referred to as a "working position" P1, in which the Figure 1A , Figure 1B , Figure 2 and Figure 5 As shown, the clamping jaws 7 are supported on the radially outer surface 3_out of the constituent element 3 of the tire, while the opposite surface forming the radially inner surface 3_in of the constituent element 3 of the tire is supported on the receiving surface 2 so as to exert a radial compression force F_clamp called "clamping force" F_clamp on the constituent element 3 of the tire, which radial compression force F_clamp holds the constituent element 3 of the tire on the receiving surface 2.

[0059] Thus, in the working position P1, the clamping jaws 7 ensure stable retention of the constituent element 3 of the tyre by gripping the receiving surface 2. This makes it possible to start the winding operation and, more specifically, to start rotating the receiving surface 2 about the central axis Z1 and to pull the constituent element 3 of the tyre behind it by means of circumferential traction, without the risk of said constituent element 3 of the tyre being displaced relative to its desired starting position on the receiving surface 2 or of accidentally becoming detached from the receiving surface 2.

[0060] Preferably, for better stability, a constituent element 3 of the tyre is compressed by the clamping force F_clamp in the direction of its thickness E3, which corresponds in this case to the distance between a radially inner surface 3_in and a radially outer surface 3_out of said element 3 and preferably to the smallest dimension of said constituent element 3 of the tyre.

[0061] It should be noted that the front end 3F of a constituent element 3 of the tire (more specifically, in this case, the strip 4) can have a straight front, that is to say a front extending perpendicularly to the two edges of the element 3 (in this case, the strip 4), or it can have an oblique front extending obliquely from one edge to the other, thus forming an angle relative to one of the edges of the element 3 (in this case, one of the edges of the strip 4) and thus forming a pointed tip.

[0062] The attachment device 5 according to the invention is particularly suitable for retaining a strip 4 having a front bevel, since it ensures a good grip of the strip 4 even if the radially outer surface 3_out of the strip 4 has a restricted surface area due to the presence of the bevel.

[0063] The attachment device 5 also comprises an actuation mechanism 10 supported by the base 6 and connecting the clamping jaws 7 to said base 6, said actuation mechanism 10 being designed to cause the clamping jaws 7 to perform alternately relative to the base 6 and therefore relative to the receiving surface 2:

[0064] - a first movement FWD, called the "engagement movement" FWD, which moves the clamping jaw 7 from the rest position P0 to the working position P1; - a second movement BWD, called the "disengagement movement" BWD, which returns the clamping jaw 7 to the rest position P0 by moving the clamping jaw 7 backwards from the working position P1 according to both a radial component BWD_R1 and an axial component BWD_A, in which case the radial component BWD_R1 is a centrifugal radial component so as to release the clamping force F_clamp, and the axial component BWD_A is used to clear the axial area 11 occupied by the constituent elements 3 of the tire on the receiving surface 2.

[0065] The clamping jaw 7 is therefore a movable jaw which is under the control of the actuating mechanism 10 .

[0066] Advantageously, when the clamping jaws 7 occupy their rest position P0, Figure 4 and Figure 8 As shown, the clamping jaws 7 are retracted to an axial distance sufficient not to hinder the laying of the subsequent component elements 3 .

[0067] Thus, for example, if the first winding operation can wind multiple turns of the strip 4 on the drum to form a reinforcement belt, the breakaway movement BWD can completely clear the space radially perpendicular to the strip 4, and more generally, can completely clear the space radially perpendicular to the reinforcement belt, thereby clearing a path for laying another component 3 (such as a tread) superimposed on the reinforcement belt.

[0068] Preferably, the trajectory T7 of the clamping jaw 7 during the disengagement movement BWD is curved so that firstly the axial component BWD_A is combined with a first radial component BWD_R1 ( Figure 6 ), according to a first radial component BWD_R1, the clamping jaws 7 move away from the central axis Z1 of the drum so as to be disengaged from the constituent element 3 of the tyre without rubbing the radially outer surface 3_out of said element 3, followed by a second radial component BWD_R2, according to which the clamping jaws approach the central axis Z1 so as to reach the rest position P0 ( Figure 8 ).

[0069] Therefore, during the disengagement movement BWD, the trajectory T7 of the clamping jaw 7 has a concave quasi-parabolic form relative to the centre axis Z1 of the drum 1 , on a radial reference plane containing the centre axis Z1 of the drum 1 .

[0070] Advantageously, a concave trajectory T7 of this type makes it possible to reach a rest position P0 in which the clamping jaws 7 protrude little or not at all radially relative to the receiving surface 2 .

[0071] More specifically, when the clamping jaws 7 are in the rest position P0, said clamping jaws 7 remain contained inside a virtual envelope centered on the central axis Z1, the radius of which, considered on a plane perpendicular to the central axis Z1, is obtained by applying a homothetic transformation centered on the central axis Z1 to the radius of the receiving surface 2 considered on said plane perpendicular to the central axis Z1, with a homothetic ratio of 105% or less, preferably 102% or less, or preferably 101% or less, optionally 100.5% or less. Thus, said virtual envelope has the same general form as the real receiving surface 2 (for example the form of a straight cylinder or a slightly curved barrel shape), but with a radius or radii (if the radius varies along the central axis Z1) slightly greater than the corresponding radius / radii of the receiving surface 2.

[0072] In other words, the thickness of the clamping jaws 7 which radially protrudes beyond the receiving surface 2 in the rest position P0 is optionally less than 5%, preferably less than 2%, or even less than 1%, or optionally less than 0.5% of the radius of the receiving surface 2 at the relevant x-axis along the central axis Z1.

[0073] As a reminder, in the rest position P0 , the additional radial thickness added by the clamping jaws 7 relative to the receiving surface 2 is preferably less than 4 mm, 3 mm or even 1.5 mm.

[0074] The radius of the receiving surface 2 for its part may for example be between 300 mm and 400 mm, in particular equal to 350 mm+ / −20 mm, in particular in the region occupied by the clamping jaws 7 in the rest position P0 .

[0075] In this case, this also keeps the attachment device 5 compact and small and, when the clamping claws 7 are in the rest position P0, prevents the claws from obstructing access to the receiving surface 2, or creating an imbalance or protruding obstruction on the drum 1, which could interfere with objects on the outside of the drum 1 during rotation of the receiving surface 2.

[0076] In particular, after placing the first component 3 of the tyre forming the reinforcement band on the drum 1 , the clamping jaws 7 are then retracted to the rest position P0 , this type of arrangement in particular enabling the tread to be laid securely over said reinforcement band forming the second component of the tyre.

[0077] The engaging movement FWD, which can be moved from the rest position P0 to the working position P1 , is preferably performed according to the same spatial trajectory T7 as the disengaging movement BWD, it being sufficient for said trajectory T7 to be traveled in the opposite direction.

[0078] Therefore, the engagement movement FWD also includes at least one centripetal radial component FWD_R2, especially in the final stage of the engagement movement FWD.

[0079] This centripetal radial component FWD_R2 facilitates the approach of the clamping jaws 7 to the outer radial surface 3_out of the constituent element 3 of the tire in a quasi-radial or fully radial manner, which ensures the application of the radial clamping force F_clamp and therefore the application of radial compression of the constituent element 3 of the tire without any risk of causing undesired axial or circumferential sliding of the constituent element 3 of the tire relative to the receiving surface 2.

[0080] It should be noted that if the engaging motion FWD follows a quasi-parabolic concave trajectory T7 in the manner of the disengagement motion BWD, the engaging motion FWD will include: a first centrifugal radial component FWD_R1 in the initial stage of the engaging motion FWD combined with an axial component FWD_A that axially moves the clamping claw toward the desired area on the receiving surface 2, and then a second centripetal radial component FWD_R2 in the final stage of the engaging motion FWD.

[0081] Preferably, the drum 1 is subdivided into a plurality of drum pieces 12 , which are distributed azimuthally around the central axis Z1 and which together form the receiving surface 2 .

[0082] In a known manner, such as Figure 1A , Figure 1B and Figure 2 As shown, this type of drum piece 12 may have edges forming comb teeth, for example, which can cooperate with each other, so that the drum piece 12 ensures the continuity of the receiving surface in the circumferential direction of the drum 1 while having relative mobility between adjacent drum pieces.

[0083] Advantageously, this relative circumferential mobility, combined with the radial expansion / contraction mechanism, makes it possible to vary the radial position of the drum blade 12 according to the size of the tyre to be built, and therefore to vary the diameter of the drum 1, and more specifically the diameter of the receiving surface 2 and therefore the circumference of the receiving surface 2, and thus the winding diameter of the constituent elements 3 of the tyre.

[0084] Preferably, the attachment means 5 are integrated in one of said drum pieces 12 .

[0085] More specifically, the base 6 can be reversibly attached (for example by being screwed) in a receptacle 13 that is hollow on the radially inner surface of the drum 12 , the radially outer surface of which forms part of the receiving surface 2 .

[0086] Furthermore, at least a portion of the actuation mechanism 10 is preferably contained in said receptacle 13 radially recessed from the receiving surface 2 .

[0087] The attachment means 5 are therefore particularly compact since they are at least partially contained in the (radial) thickness of the drum 12 itself and more generally at least partially or almost completely inside the envelope radially delimiting the receiving surface 2 around the centre axis Z1 .

[0088] Preferably, the attachment means 5 are situated on the axially outer edge of the drum blade 12, i.e. on the free edge of the drum blade 12, corresponding to the edge of said drum blade 12 axially farthest from a plane called the “equatorial plane” PE of the drum. The equatorial plane PE of the drum is a plane perpendicular to the central axis Z1 and situated halfway along the width of the drum 1, i.e. axially equidistant from each axial end of the drum 1 and more specifically from each axial end of the receiving surface 2.

[0089] Therefore, by being placed at the inclined surface of the drum piece 12, and more generally at the inclined surface of the drum 1, the attachment device 5 does not interfere with the receiving surface 2 and the clamping claw 7 can be easily retracted to the rest position P0, which is located at the free axial end of the receiving surface 2 and is axially spaced from the central area of ​​the receiving surface 2.

[0090] Advantageously, when in the rest position P0, the clamping claw 7 remains axially contained in the entire axial area occupied by the drum 1, more specifically, in the entire axial area occupied by the receiving surface 2, so that the clamping claw 7 does not protrude axially relative to the lateral slope of the drum 1, more specifically, does not protrude axially relative to the receiving surface 2, in particular does not protrude axially relative to the axial outermost edge of the drum piece 12 carrying the attachment device 5.

[0091] Therefore, by being inscribed in the axial envelope of the drum 1, and more specifically inscribed in the axial envelope of the receiving surface 2, the attachment device 5 has good compactness and reliable and safe operation, because it is not easy to collide with objects axially close to the drum 1 during the rotational movement of the drum 1 around the central axis Z1.

[0092] According to preferred features of the attachment device 5, the attachment device itself may constitute an invention, in particular suitable for different types of tire building supports other than the drum 1, such as Figures 3 to 8It can be clearly seen that the actuating mechanism 10 comprises an articulated quadrilateral 20, whose first and second vertices are respectively formed by a first pivot 21 belonging to the base 6 and a second pivot 22 belonging to the base 6, and whose third and fourth vertices are respectively formed by a third pivot 23 and a fourth pivot 24 both belonging to a platform 25 supporting the clamping jaw 7.

[0093] In the reference system attached to the base 6 and therefore to the receiving surface 2, the base 6 forms a fixed base and the platform 25 forms a movable platform 25 designed to alternately first reach the first position ( Figure 4 , Figure 8 ), the first position corresponds to the position where the clamping claw 7 attached to the platform 25 is in the rest position P0, and then reaches the second position ( Figure 3 , Figure 5 ), in this second position, the clamping jaws 7 attached to the platform 25 are in the working position P1.

[0094] Advantageously, the articulated quadrilateral structure 20 according to the invention is particularly simple and strong and can provide a concave quasi-parabolic trajectory T7 for the clamping jaws 7 , which provides the advantages described above.

[0095] The respective axes Z21 , Z22 , Z23 , Z24 of the first, second, third and fourth pivots 21 , 22 , 23 , 24 are parallel to each other.

[0096] This allows the articulated quadrilateral 20 to deform in a plane containing the central axis Z1 of the drum 1 , in this case a radial plane.

[0097] More specifically, the axes Z21, Z22, Z23, Z24 of the first, second, third and fourth pivots 21, 22, 23, 24 are all perpendicular to the same radial reference plane (called the "sagittal plane" PS), which contains the central axis Z1 of the drum 1 and subdivides the drum 1 into two parts substantially opposite each other.

[0098] By convention, the sagittal plane PS preferably corresponds to a radial plane containing first the central axis Z1 and secondly a radius perpendicular to the central axis Z1, and corresponds to a bisector which divides the angular sub-sector covered by the drum 12 in azimuth around the central axis Z1 into two equal angular sub-sectors.

[0099] Furthermore, the first, second, third and fourth pivot axes 21 , 22 , 23 , 24 are advantageously different from each other and are not coaxial with each other, so that the vertices of the articulated quadrilateral 20 are different from each other and are spaced apart.

[0100] It should also be noted that the first pivot 21 is radially closer to the central axis Z1 than the third pivot 23, and similarly, the second pivot 22 is radially closer to the central axis Z1 than the fourth pivot 24. In this case, the first pivot 21 is also radially closer to the central axis Z1 than the second pivot 22.

[0101] like Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 and Figure 8 It can be clearly seen that the platform 25 is preferably first connected to the base 6 via the first arm 26, and the first arm 26 connects the first pivot 21 to the third pivot 23, thereby defining the first side 26A of the articulated quadrilateral 20, and the platform 25 is secondly connected to the base 6 via the second arm 27, and the second arm 27 connects the second pivot 22 to the fourth pivot 24, thereby defining the second side 27A of the articulated quadrilateral 20.

[0102] It should be noted that no matter what the form of the first arm 26 used to substantially connect the first pivot 21 with the third pivot 23, the "first side" 26A will represent a straight line segment geometrically connecting the first pivot 21 with the third pivot 23, and more specifically, represents a straight line segment perpendicular to the axis Z21 of the first pivot 21 and the axis Z23 of the third pivot 23 and intersecting the axis Z21 of the first pivot 21 and the axis Z23 of the third pivot 23, so that on the above-mentioned sagittal plane PS, the straight line segment connects the rotation center of the first pivot 21 with the rotation center of the third pivot 23, that is, connects the first vertex of the articulated quadrilateral 20 with the third vertex of the articulated quadrilateral 20.

[0103] Similarly, the “second side” 27A represents a straight line segment that geometrically connects the second vertex of the articulated parallelogram 20 (and therefore the center of rotation of the second pivot 22) with the fourth vertex of the articulated parallelogram 20 formed by the center of rotation of the fourth pivot 24, regardless of the material form of the second arm 27.

[0104] It should be noted that the form of the first arm 26 and the form of the second arm 27 may be varied, respectively, without departing from the context of the present invention.

[0105] In this case, in order to simplify the construction, the first arm 26 and the second arm 27 are preferably straight.

[0106] Preferably, the first arm is formed by a connecting rod or a pair of connecting rods parallel to each other, each connecting rod connecting the first pivot 21 to the third pivot 23. Similarly, the second arm 27 is formed by a connecting rod or a pair of connecting rods parallel to each other, each connecting rod connecting the second pivot 22 to the fourth pivot 24.

[0107] The receptacle 13 hollow on the drum 12 in order to receive at least a part of the base 6 and the actuating mechanism 10 will preferably be a through opening leading to the radially outer surface of the drum 12 in order to allow the passage of the first arm 26 and the second arm 27, and the travel of said arms 26, 27 and the platform 25 during the engagement movement FWD and the disengagement movement BWD. Preferably, the receptacle 13 will thus form a recess cut into the axially outermost edge of the drum 12.

[0108] It should be noted that the attachment device 5 will preferably be designed so that: whether in the rest position P0 or in the working position P1, the radially outermost surface of the platform 25 to which the first arm 26 and the second arm 27 and the clamping claw 7 are attached are located at a position radially recessed from the radially outer surface of the drum piece 12, that is, they are closer to the central axis Z1 than the radially outer surface of the drum piece 12, and are recessed relative to the viewing surface and the receiving surface 2 of the drum piece 12. In this case, this arrangement will also contribute to the compactness of the attachment device 5.

[0109] The first arm 26 provides a fixed length L26A for the first side 26A, i.e. it establishes a constant distance between the first pivot 21 and the third pivot 23, i.e. the first arm 26 maintains a constant distance between the centers of the first pivot 21 and the third pivot 23. Therefore, during the engagement movement FWD and then the disengagement movement BWD, the length L26A of the first side 26A will be constant.

[0110] In this case, a fixed adjustment system may be provided so that before performing the engagement movement FWD and then the disengagement movement BWD, the length L26A of the first side may be modified in order to adjust the desired distance between the centers of the first pivot 21 and the third pivot 23. To this end, the first arm 26 may, for example, have a telescopic structure with an adjustable length, which may be locked at the desired length by any means (e.g., screws).

[0111] The same applies to the second arm 27 which will define a length L27A of the second side 27A, ie the distance between the centres separating the second pivot 22 from the fourth pivot 24, which will be fixed and optionally adjustable by an adjustment system.

[0112] This type of adjustment system will be able to adjust the working position P1 particularly advantageously according to the thickness E3 of the constituent element 3 of the tyre which it is desired to retain by clamping on the receiving surface 2 .

[0113] Particularly preferably, the length of the second side L27A (i.e., the distance separating the axis Z24 of the fourth pivot 24 from the axis Z22 of the second pivot 22 as indicated above) is less than the length of the first side L26A (i.e., the distance separating the axis of the third pivot 23 from the axis of the first pivot 21 as indicated above):

[0114] L27A <L26A

[0115] In other words, the second arm 27 is shorter than the first arm 26 .

[0116] Due to this difference in length between the first arm 26 and the second arm 27, the articulated quadrilateral 20 forms a "pseudo parallelogram", which advantageously allows the tilting component BWD_P of the clamping jaw 7 during the disengagement movement BWD to be combined with the above-mentioned overall parabolic trajectory T7 in pitch around the circumferential direction X1.

[0117] This pitching-type tilting BWD_P that occurs at the beginning of the disengagement movement BWD advantageously enables the clamping jaws 7 to be disengaged from the radially outer surface 3_out of the constituent element 3 of the tire supported on the receiving surface 2, without the clamping jaws 7 exerting any friction on said constituent element 3 of the tire and therefore without axial traction.

[0118] Therefore, when the clamping jaws 7 leave their working position P1 to reach their rest position P0 , there is no risk of accidental displacement of the front end 3F of said constituent element 3 of the tyre.

[0119] This type of arrangement using arms 26, 27 of different lengths also has the advantage of emphasizing the radial nature of the approach orientation during the final phase of the engagement movement FWD, thereby contributing to the generation of a very strong radial clamping force F_clamp.

[0120] It should be noted that the shorter arm (in this case the second arm 27) and therefore the second pivot 22 and the fourth pivot 24 are axially closer to the portion of the receiving surface 2 that receives the constituent element 3 of the tire than the longer arm (in this case the first arm 26) and the first pivot 21 and the third pivot 23.

[0121] In equivalent manner, the first 21 and third 23 pivots and the first arm 26 (long arm) are therefore axially further from the equatorial plane PE of the drum 1 than the second 22 and fourth 24 pivots and the second arm 27 (short arm) on the same side of said equatorial plane PE.

[0122] The actuating mechanism 10 may be driven by any type of motor, ie an electric motor, a pneumatic motor or a hydraulic motor.

[0123] Preferably, the actuating mechanism 10 is driven by an actuator 30, for example a double-acting pneumatic actuator, whose body 31 is supported by the base 6 and whose rod 32 is engaged on the first arm 26 at a fifth pivot 33, said rod 32 being hinged on said first arm 26 via the fifth pivot 33. This fifth pivot 33 is located between the first pivot 21 and the third pivot 23 and at a certain distance from each of said first and third pivots 21, 23.

[0124] The axis Z33 of the fifth pivot 33 is also parallel to the axes Z21 , Z22 , Z23 , Z24 of the first, second, third and fourth pivots 21 , 22 , 23 , 24 .

[0125] Advantageously, this type of highly compact arrangement allows the jack 30 to cause the tilting of the first arm 26 and thus the deformation of the articulated quadrilateral 20, which in turn causes the platform 25 and the clamping jaws 7 to move alternately in the direction corresponding to the engagement movement FWD (in Figures 5 to 8 In the case of the first arm 26, by tilting the first arm 26 clockwise, by retracting the rod 32 into the body 31 in a linear direction, and then in the opposite direction corresponding to the disengagement movement BWD (in Figures 5 to 8 In the case of the above, the first arm 6 is tilted in the counterclockwise direction and the rod 32 is displaced from the main body 31 toward the left side.

[0126] Preferably, in particular in order to contribute to the compactness of the attachment device 5 , the fifth pivot 33 is radially further from the centre axis Z1 than the first pivot 21 and radially closer to said centre axis Z1 than the second pivot 22 .

[0127] Preferably, the main body 31 of the actuator 30 is hinged on the base 6 at a sixth pivot 34 , and the axis Z34 of the sixth pivot is parallel to the axis Z33 of the fifth pivot 33 .

[0128] The actuator 30 is preferably positioned in the receptacle 13 substantially parallel to the central axis Z1, opposite the radially inner surface of the drum 32, so that the displacement direction of the translation of the rod 32 is parallel to the central axis Z1 within + / - 10°. For this purpose, the sixth pivot 34 is preferably axially closer to the equatorial plane PE than the fifth pivot 33. This type of arrangement makes it possible to reconcile compactness and power of the actuating mechanism 10.

[0129] According to the preferred features of the attachment device 5, the attachment device itself may constitute an invention, suitable for different types of actuation mechanisms 10, and / or suitable for different types of tire building supports, it being understood that the attachment device comprises an articulated quadrilateral 20 actuation mechanism 10 as described above, whether the support is a drum 1 or another type of support, such as Figure 3 and Figure 4As is clearly shown in FIG. 1 , the clamping jaw 7 is formed by a leaf spring 40 which is designed to be able to bend elastically, for example under the stress of a clamping force F_clamp.

[0130] The clamping jaw 7 is therefore not only simple, light, compact and strong, but also has flexibility (pliability) which allows it to bend elastically in contact with the constituent element 3 of the tyre, under the action of the clamping force F_clamp, against the resistance opposed by the underlying receiving surface 2.

[0131] Therefore, the clamping action generated by the forced application of the leaf spring 40 to the component 3 of the tire, under the action of the cylinder 30 transmitted via the actuating mechanism 10 (in particular via the first arm 26 forming the lever), automatically adapts to the thickness E3 and the inherent compression stiffness of the component 3 of the tire.

[0132] The leaf spring 40 is advantageously mounted flat on the platform 25 so that the thickness E40 of the leaf spring 40 is oriented in the radial direction Y1 (in this case, the radial direction Y1 together with the center axis Z1 generates the above-mentioned sagittal plane PS) so as to allow bending which has the effect of bending the leaf spring 40 around the circumferential direction X1, i.e., bending caused by the bending moment supported in the circumferential direction X1.

[0133] As a reminder, the leaf spring 40 can be made of steel, in particular spring steel containing silicon, or an alloy based on aluminum, or also of a composite material. Preferably, the surface of the leaf spring 40 (in this case the radially inner surface of said leaf spring 40) is designed to be in contact with the component element 3 of the tire (thus in this case the radially outer surface 3_out of said component element 3 of the tire) and can be coated with an anti-sticking material, for example

[0134] Preferably, the thickness of the leaf spring 40 may be between 0.5 mm and 3 mm, for example between 1 mm and 2 mm.

[0135] This relative fineness not only makes it possible to provide the leaf spring 40 with good flexibility and appropriate flexural elasticity, but also to minimize the radial dimensions of said leaf spring 40, thereby limiting the interference between said leaf spring 40 and the guiding and laying unit responsible for transferring the constituent elements 3 of the tire to the drum 1, as well as for positioning and guiding said constituent elements 3 of the tire relative to the drum 1 during the winding operation, when the clamping jaws 7 (and therefore in this case the leaf spring 40) occupy the working position P1.

[0136] In particular, the narrow thickness of the leaf spring 40 limits the radial height of any protrusion formed by the leaf spring 40 on the receiving surface 2 in the working position 1P1 and therefore allows an application roller designed to apply the constituent element 3 of the tire on the drum 1 to roll in the circumferential direction X1 on the receiving surface 2 and, by partially passing over the leaf spring 40, pass over the position occupied by the leaf spring 40 and therefore pass over the protrusion without causing any damage to the application roller, the constituent element 3 of the tire or the leaf spring 40.

[0137] According to a possible arrangement, in this respect, the lateral ridges of the radially outer surface of the leaf spring 40 can also be chamfered or rounded, in this case parallel to the central axis Z1, so as to form a ramp that will facilitate the application roller to pass over said ridges in the circumferential direction X1.

[0138] Preferably, if Figure 3 , Figure 5 , Figure 6 , Figure 7 and Figure 8 As can be clearly seen in the figure, the leaf spring 40 is assembled in a cantilevered manner so as to have firstly a controlled portion 40A attached and supported on the platform 25 and secondly a free end 40B protruding axially relative to the platform 25 so as to be able to come into contact with the constituent element 3 of the tire when the clamping jaws 7 are moved to the working position P1.

[0139] In this case, too, this type of arrangement contributes to the lightness, simplicity and robustness of the attachment device 5 , while ensuring good flexibility of the clamping jaws 7 .

[0140] Preferably, in particular Figure 3 As shown, the leaf spring 40 comprises at least one groove 41 extending axially over a portion of its length so as to subdivide said leaf spring 40 into at least two tongues 42, 43, each of which is designed to come into contact with a constituent element 3 of the tire when the clamping jaws 7 are in the working position P1 and each of which occupies a different angular sector around the central axis Z1.

[0141] Preferably, the subdivision into tongues 42, 43 makes it possible to reduce the stiffness of the leaf spring 40 and therefore increase its flexibility, while maintaining a sufficiently large thickness E40 to allow the leaf spring to resist plasticization under the clamping force F_clamp, that is, without causing the leaf spring 40 to undergo irreversible plastic deformation when it is pressed against the constituent element 3 of the tire.

[0142] Therefore, the presence of at least one groove 41 increases the flexibility of the attachment device 5 relative to the leaf spring 40, when the leaf spring 40 is in the working position P1, the leaf spring 40 is solid over its entire length (considered in the circumferential direction X1), that is, it is solid over the entire circumferential portion of the receiving surface 2 covered by the leaf spring 40 around the center axis Z1.

[0143] Furthermore, the subdivision into at least two tongues 42, 43 makes it possible to dedicate each of said tongues 42, 43 to a specific angular sector about the centre axis Z1, so that each tongue 42, 43 generates its own support on the constituent element 3 of the tyre independently of the other tongue 43, 42, so that the clamping jaws 7 (in this case the leaf springs 40) are better adapted, by means of a double support, to the curvature of the drum 1 considered in a plane perpendicular to the centre axis Z1.

[0144] Preferably, if Figure 3 and Figure 4 As shown, the groove 41 extends axially to the axial end of the free end 40B of the leaf spring 40. Thus, at least two tongues 42, 43 form terminal tongues 42, 43, whose respective axial ends are free, in particular can be bent freely independently of each other.

[0145] According to this type of arrangement, at least two tongues 42 , 43 form free ends 40B, whereas they are attached to, in this case integrally formed with, a single common base, which itself forms a controlled portion 40A attached to the platform 25 .

[0146] It should be understood that the present invention also pertains to a tire building apparatus 50 comprising:

[0147] -frame 51;

[0148] - a drum 1 according to any possible variant of the invention, said drum 1 being mounted in rotation relative to a frame 51 so as to be able to rotate about itself around its central axis Z1;

[0149] - at least one supply system 52, which is designed to convey the constituent elements 3 of the tire in the form of a strip 4 to the drum 1, so that the front end 3F of the strip 4 supplied by the supply system 52 can be attached to the receiving surface 2 of the drum 1 by means of the attachment device 5, and then the strip 4 is wound on the receiving surface 2 around the central axis Z1 at least one complete revolution, preferably a plurality of complete revolutions, by rotating the drum 1 around its central axis Z1.

[0150] In a known manner, the rotation of the drum relative to the frame 51 , which can be achieved by an electric motor, makes it possible to wind each strip 4 and thus close it in a loop on itself around the central axis Z1 .

[0151] The supply system 52 can, for example, be formed by a pay-out device that receives a bobbin storing the strip 4 and from which the strip is then unwound as it is wound onto the drum 1, or by a calender that continuously produces the required number of strips 4 by passing a reinforcing thread and two fine rubber layers sandwiching the reinforcing thread simultaneously between two rollers that define an air gap corresponding to the thickness E3 of the strip 4.

[0152] As previously mentioned, the supply system 52 may comprise guiding and laying units (not shown), in particular application rollers, making it possible to guide the strip 4 and to apply said strip 4 onto the receiving surface 2 of the drum 1 .

[0153] Furthermore, the attachment device 5, more generally the drum 1 and therefore the tyre building apparatus 50 preferably comprises a set of replaceable clamping jaws 7 in the form of a set of multiple leaf springs 40 of different lengths, so as to be able to adapt the clamping device 5 according to the axial position and / or the axial width W3 of the constituent elements 3 of the tyre that it is desired to retain on the drum 1.

[0154] Thanks to this plurality of removable and replaceable leaf springs 40 , the attachment means 5 and more generally the drum 1 thus equipped have great versatility, since it can be adapted to various models and sizes of tires.

[0155] Preferably, a plurality of leaf springs 40, or even all leaf springs 40, are slotted to have tongues 42, 43 as described above.

[0156] The invention also relates to a tyre building process, during which the leading end 3F of a constituent element 3 of the tyre 3, in this case a strip 4, is held on a drum 1 according to the invention by means of an attachment device 5 supported by said drum 1, while said constituent element 3 of the tyre, in this case a strip 4, is wound on said drum 1.

[0157] Preferably, during the production process of this tyre, a constituent element 3 of the tyre, in this case a strip 4, is wound starting from a front end 3F of said constituent element of the tyre forming the starting point of a first of a plurality of consecutive spiral turns including at least one second turn following the first.

[0158] The spiral turns are axially offset relative to one another so that they do not axially overlap the front end 3F of the constituent element 3 of the tyre, or at most only partially axially overlap said front end 3F.

[0159] According to this same process, the dimensions of the clamping claw 7 (in this case the axial length of the leaf spring 40) are chosen so that when the clamping claw 7 is in the working position P1, in order to hold the front end 3F on the receiving surface 2 of the drum 1, the clamping claw 7 is interrupted axially before the axial area occupied by the second and subsequent turns, so that no turn covers and encircles the clamping claw 7.

[0160] Advantageously, since the clamping jaws 7 (in this case the leaf springs 40) are never wedged by the rings of the constituent elements 3 of the tire, since said clamping jaws 7 are placed on a first ring but are interrupted axially before the edge of a second ring, it is possible to withdraw the clamping jaws 7 so as to leave their working position P1 and return them to their rest position P0 without disturbing or damaging the annular unit formed by the assembly of said rings.

[0161] Now refer to Figure 5 , Figure 6 , Figure 7 and Figure 8 The operation of the attachment device according to the present invention will be briefly described.

[0162] initial( Figure 8 ), the clamping jaws 7 (for convenience, hereinafter likened to leaf springs 40) are in a rest position P0 outside the area of ​​the receiving surface 2 where the constituent element 3 of the tyre will be located. For ease of description, said constituent element 3 of the tyre will hereinafter be likened to a strip 4. The drum 1 is stationary.

[0163] The leaf springs 40 supported by the platform 25 are selected and replaced if necessary so that the attachment system 5 is adapted to the tire that one wishes to build. If applicable, by means of the adjustment system, the fixing rules of the actuating mechanism 10 are also adjusted, in this case in particular the respective fixing lengths L26A, L27A of the first and second arms 26, 27 of the articulated quadrilateral 20.

[0164] Once the attachment system 5 is ready, the supply system 52 supplies at least a portion of the strip 4 in the desired starting position, the front end 3F of the strip being applied to the receiving surface 2. This starting position is such that it at least partially overlaps the working position P1, which is thus defined by the travel range of the actuating mechanism 10 of the attachment system 5 and the dimensions of the leaf spring 40 chosen.

[0165] The activation of the jack 30 is then commanded by a suitable control unit, causing the jack 30 to actuate its rod 32, in this case to retract said rod 32 into the body 30, and thus to cause the first arm 26 to tilt, in this case along Figure 7 , Figure 6 and Figure 5 Tilt in clockwise direction.

[0166] This forced tilting of the first arm 26 causes deformation of the articulated quadrilateral 20 about its pivots 21 , 22 , 23 , 24 and is therefore transformed into a concave, quasi-parabolic movement of the platform 25 and, in turn, of the leaf spring 40 supported by said platform 25 relative to the central axis Z1 .

[0167] In the first phase of the engagement movement FWD corresponding to the rising phase of the quasi-parabolic trajectory T7 (from Figure 8 to Figure 7 During the transition period, the leaf spring 40 radially rises according to the first centrifugal radial component FWD_R1 and starts to advance according to the axial component FWD_A directed to the equatorial plane PE of the drum until it reaches the apogee of its trajectory T7, corresponding to Figure 7 The position indicated in .

[0168] Preferably, the actuating mechanism 10 is designed so that at this remote point, both the first arm 26 and the second arm 27 extend radially simultaneously, i.e. the third pivot 23 is radially vertically aligned with the first pivot 21, and the fourth pivot 24 is radially vertically aligned with the second pivot 22. This choice of configuration at the remote point of the trajectory T7, which corresponds substantially to a position located halfway between the rest position P0 and the working position P1, in particular enables the relative parallelism between the leaf spring 40 and the receiving surface 2 to be maintained in each of the two useful end positions of the trajectory T7, i.e. the rest position P0 and the working position P1.

[0169] The engagement movement FWD continues through a descending phase of a quasi-parabolic trajectory T7, combining an axial component FWD_A directed toward the equatorial plane PE and a second radial component FWD_R2 (centripetal in this case), which causes the leaf spring 40 to descend toward the central axis Z1 and therefore toward the receiving surface 2, thus gradually approaching the strip 4 ( Figure 6 ), more specifically, gradually approaching the radially outer surface 3_out of the strip 4 until reaching the working position P1, in which the leaf spring 40 is supported against the strip 4 ( Figure 5 ).

[0170] The traction force exerted on the rod 32 of the jack 30 is therefore in the form of a substantially radial clamping force F_clamp which places the strip 4 against the receiving surface 2 in the desired position forming the start of winding.

[0171] It should be noted that, advantageously, during the descending phase of the engagement movement FWD, the difference in length between the first arm 26 and the second arm 27 causes the leaf spring 40 to tilt in a pitching pattern FWD_P, in this case at Figure 6 and Figure 5The tilt in the clockwise direction around the circumferential direction X1 in the form of a pitch lowers the slotted free end 40B of the leaf spring 40 and thus helps to apply the leaf spring 40 in a quasi-radial direction on the radial outer surface 3_out of the strip 4, thereby quasi-perpendicular to the receiving surface 2, without causing the strip 4 to produce undesired axial movement on the receiving surface 2.

[0172] Furthermore, the flexibility of the leaf spring 40 allows it to deform elastically when in contact with the strip 4 supported by the receiving surface 2 , thereby flexibly adapting the clamping force F_clamp and the clamping distribution according to the geometry and dimensions of the drum 1 and the strip 4 .

[0173] Once the strip 4 is locked on the receiving surface 2 by the attachment means 5 ( Figure 5 , Figure 1A ), the drum 1 starts to rotate around the central axis Z1.

[0174] During this rotational movement, the attachment device 5 is driven integrally with the drum 1 and, since the attachment device 5 firmly holds the strip 4 at a selected position in the circumferential direction of the drum 1 , the strip 4 is driven by a longitudinal traction force in the circumferential direction X1 and begins to be wound onto the drum 1 .

[0175] The rotation of the drum continues for the necessary time in order to produce the desired number of turns of the strip 4 on the drum 1 .

[0176] Preferably, this rotation of the drum 1 is accompanied by a relative axial displacement of the supply system 52, more specifically of the application roller, relative to the drum 1 parallel to the central axis Z1, so as to produce a multi-turn helical winding with the desired pitch.

[0177] Once the winding of the strip 4 is completed, the rotation of the drum 1 is stopped and the attachment means 5 are then actuated again, this time in order to release the strip 4 by performing a detaching movement BWD.

[0178] Optionally, before carrying out the disengagement movement BWD, the clamping jaws 7 can be temporarily kept in the working position P1 for a period of time required to reconfigure the drum 1 and, more generally, the device 50, with the purpose of carrying out a second winding operation intended to place another constituent element 3 of the tire on the drum 1, on top of the strip 4 placed during the first winding operation.

[0179] For example, the clamping jaws 7 can thus be kept in the working position P1 for a time that is necessary to transfer the drum 1 carrying the strip 4 from the shaping station where the winding operation of the strip 4 is carried out to another distant shaping station designed to perform another winding operation aimed at placing another constituent element 3 of the tire on the drum 1, on top of the strip 4. According to another example, the clamping jaws 7 can be kept in the working position P1 for a time that is necessary to reorient the drum 1 in an azimuth about the central axis Z1 within the shaping station already used for winding the strip 4, so as to define the starting position where it is desired to wind a new constituent element 3 of the tire on top of the strip 4 already in place. The clamping jaws can also be kept in the working position P1 until the laying of the new constituent element 3 of the tire on top of the strip 4 begins.

[0180] To perform the disengaging movement BWD, the rod 32 of the jack 30 is extended so as to tilt the first arm 26 in the direction opposite to that previously used for the engaging movement FWD, thus in this case in the direction of the engagement movement FWD. Figures 6 to 8 Tilt counterclockwise in the.

[0181] The return trajectory T7 corresponding to the disengaging movement BWD is the same as the trajectory of the engaging movement FWD, but travels in the opposite direction.

[0182] Therefore, there is again a first ascending phase ( Figure 6 and Figure 7 ), during which there is a combination of a tilt in the form of a pitch BWD_P, a first centrifugal radial component BWD_R1, and an opposing axial component BWD_A in a direction away from the equatorial plane PE, which can disengage the leaf spring 40 and move it away from the strip 4. Advantageously, the leaf spring 40 is disengaged and removed from the strip 4 without exerting friction or axial or circumferential traction on the strip 4.

[0183] Once past the apogee ( Figure 7 ), then the withdrawal trajectory T7 includes a descending phase ( Figure 7 and Figure 8 ), which combines the withdrawn axial component BWD_A and the second radial component BWD_R2, which in this case is the centripetal radial component, and which can return the leaf spring to the position lowered to the drum 12, i.e., the rest position P0 ( Figure 8 ). Thus, the device 50 provides a clear area of ​​access to the receiving surface 2 carrying the winding strip 4, in order to continue laying another constituent element 3 of the tyre on top of said winding strip 4, or to remove from the drum 1 the annular unit formed by said winding strip 4.

[0184] It should be understood that the present invention is by no means limited to the variant embodiments disclosed above. In particular, a person skilled in the art can separate or freely combine one or another of the above features, or replace them by an equivalent method.

[0185] In particular, it is possible to envisage adapting the attachment device 5 comprising an articulated quadrilateral 20 supported by a base 6 and a leaf spring 40, in particular a slotted leaf spring 40, to any type of application, regardless of the type of forming support for which it is designated and to which the attachment device 5 is attached.

Claims

1. A drum (1) for building tyres, said drum (1) having a central axis (Z1) and a radially outer surface (2), called "receiving surface" (2), extending along and around said central axis (Z1) and designed to receive at least one component element (3) of said tyre, said drum comprising attachment means (5) designed to retain said component element (3) of said tyre on said receiving surface (2), said drum being characterized in that said attachment means (5) comprise: - a base (6) attached to the drum (1) such that the attachment means (5) are supported by said drum (1); - a clamping jaw (7) designed to adopt a so-called "working position" (P1) in which it bears on a radially outer surface (3_out) of a constituent element (3) of the tyre, while the opposite surface of said constituent element (3) of the tyre forms a radially inner surface (3_in) and bears on a receiving surface (2), so as to exert on said constituent element (3) of the tyre a radial compression force, called "clamping force" (F_clamp), which holds said constituent element (3) of the tyre on said receiving surface (2); - an actuating mechanism (10) supported by the base (6) and connecting the clamping jaw (7) to said base (6), said actuating mechanism (10) being designed to cause the clamping jaw (7) to perform alternately a first movement (FWD), called "engagement movement" (FWD), relative to the base (6) and therefore relative to the receiving surface (2), wherein said first movement (FWD) causes the clamping jaw (7) to move from a rest position (P0) to an operating position (P1), and a second movement (BWD), called "disengagement movement" (BWD), which causes the clamping jaw (7) to return to the rest position (P0) by displacing the clamping jaw (7) according to both a radial component (BWD_R1) for releasing the clamping force (F_clamp) and an axial component (BWD_A) for clearing the axial area (11) occupied by the constituent elements (3) of the tire on the receiving surface (2).

2. The drum according to claim 1, characterized in that The actuating mechanism (10) comprises an articulated quadrilateral (20), wherein the first vertex and the second vertex of the articulated quadrilateral (20) are respectively formed by a first pivot (21) belonging to the base (6) and a second pivot (22) belonging to the base (6), and the third vertex and the fourth vertex of the articulated quadrilateral (20) are respectively formed by a third pivot (23) and a fourth pivot (24) both belonging to a platform (25) supporting the clamping claw (7), wherein the corresponding axes (Z21, Z22, Z23, Z24) of the first pivot (21), the second pivot (22), the third pivot (23) and the fourth pivot (24) are parallel to each other, and the platform (25) is firstly moved by a first arm (26) , and secondly connected to the base through a second arm (27), the first arm (26) connects the first pivot (21) to the third pivot (23), thereby defining a first side (26A) of the articulated quadrilateral (20), the second arm (27) connects the second pivot (22) to the fourth pivot (24), thereby defining a second side (27A) of the articulated quadrilateral (20), the length (L27A) of the second side (27A), i.e. the distance separating the axis (Z24) of the fourth pivot from the axis (Z22) of the second pivot, is less than the length (L26A) of the first side (26), i.e. the distance separating the axis (Z24) of the third pivot (23) from the axis (Z21) of the first pivot.

3. The drum according to claim 2, characterized in that The actuating mechanism (10) is driven by an actuator cylinder (30), the main body (31) of the actuator cylinder (30) is supported by a base (6), the rod (32) of the actuator cylinder (30) is engaged with the first arm (26) at a fifth pivot (33), the rod (32) is hinged to the first arm (26) via the fifth pivot (33), and the fifth pivot (33) is located between the first pivot (21) and the third pivot (23), and has a certain distance from each of the first pivot (21) and the third pivot (23).

4. A drum according to any one of the preceding claims, characterised in that The clamping claw (7) is formed by a leaf spring (40) which is designed so as to be able to bend elastically under the stress of the clamping force F_clamp.

5. A drum according to claim 4 and any one of claims 2 or 3, characterized in that The leaf spring (40) is mounted in cantilevered fashion so as to have firstly a controlled portion (40A) attached to the support on the platform (25) and secondly a free end (40B) projecting axially relative to the platform (25) so as to be able to come into contact with a constituent element (3) of the tyre when the clamping jaws (7) are brought to the working position (P1).

6. A drum according to any one of claims 4 or 5, characterized in that The leaf spring (40) comprises at least one groove (41) extending axially over a portion of its length so as to subdivide the leaf spring (40) into at least two tongues (42, 43), each of which is designed to come into contact with a constituent element (3) of the tire when the clamping jaw (7) is in the working position (P1) and each of which occupies a different angular sector around the central axis (Z1).

7. A drum according to any one of the preceding claims, characterised in that The drum is subdivided into a plurality of drum segments (12) which are distributed azimuthally around a central axis (Z1) and thus jointly form a receiving surface (2), wherein the attachment device (5) is incorporated in one of the drum segments (12).

8. A tire building device (50), comprising: -frame (51); - A drum (1) according to any one of claims 1 to 7, mounted to rotate relative to a frame (51) so as to be able to rotate about itself around its central axis (Z1); - at least one supply system (52) designed to convey the constituent elements (3) of the tire in the form of a strip (4) to the drum (1), so that the front end (3F) of the strip (4) supplied by the supply system (52) can be attached to the receiving surface (2) of the drum by means of an attachment device (5), and then the strip (4) is wound around the central axis (Z1) on the receiving surface (2) at least one complete revolution, preferably a plurality of complete revolutions, by rotating the drum (1) around its central axis (Z1).

9. The device according to claim 8, characterized in that The tire building device comprises a set of replaceable clamping jaws (7) in the form of a set of multiple leaf springs (40) of different lengths so as to be able to adapt the clamping device (5) according to the axial position and / or the axial width (W3) of the constituent elements (3) of the tire that it is desired to retain on the drum (1).

10. Method for producing a tyre, during which the leading end (3F) of a constituent element (3) of the tyre is held on a drum (1) according to any one of claims 1 to 7 by means of attachment means (5) supported by the drum (1) while the constituent element (3) of the tyre is wound on the drum (1).

11. A method according to claim 10, during which the constituent element (3) of the tyre is wound from a front end (3F) of the constituent element of the tyre, the front end (3F) forming the starting point of a first turn of a plurality of consecutive spiral turns, the plurality of consecutive spiral turns comprising at least one second turn after the first turn, the plurality of consecutive spiral turns being axially offset relative to each other so that the turns do not axially overlap with the front end (3F) of the constituent element of the tyre, or at most only partially overlap axially with the front end (3F), and during which the dimensions of the clamping jaws (7) are chosen so that when the clamping jaws (7) are in the working position (P1), in order to hold the front end (3F) on the receiving surface (2) of the drum (1), the clamping jaws (7) are interrupted axially before the axial area occupied by the second and subsequent turns, so that no turns cover and encircle the clamping jaws (7).

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