Device and method for welding a rubber strip

Abstract

The present invention relates to an assembly and welding machine (100) used for manufacturing a pre-cured tire, said assembly and welding machine (100) serving to weld the two ends, also referred to respectively as the first and second lips (7a, 7b), of a rubber strip (7) wound onto a construction drum (1). The assembly and welding machine (100) comprises a hot blade (5) and a pressure mechanism (18) designed to improve the welding of the first and second lips (7a, 7b) by heating by contact and applying pressure at the respective points of the first and second lips (7a, 7b). The invention also relates to a method of implementing the assembly and welding machine (100). [Figure 6]

Description

Title of the invention: Device and method for welding a rubber strip

[0001] The present invention relates to the field of tire manufacturing and more particularly to the field of assembling tire components before curing.

[0002] The present invention relates more particularly to a device and a method for welding the ends of a non-vulcanized rubber strip wound on a sewing drum.

[0003] Pre-cured tires are generally manufactured by assembly machines comprising a cylindrical drum around which unvulcanized rubber strips are wound. These rubber strips may or may not have metallic or textile reinforcements. In other words, a rubber strip contains at least one rubber material. Furthermore, a rubber strip can be geometrically characterized by a longitudinal length, more simply called the length, and a cross-section, having a smaller dimension called the thickness and a larger dimension called the width. In what follows, the thickness of the cross-section of the rubber strip is also more simply called the thickness of the rubber strip, and the width of the cross-section of the rubber strip is also more simply called the width of the rubber strip.

[0004] Rubber strips are generally obtained by cutting long rubber profiles, produced by extrusion or calendering processes or any other process known to those skilled in the art, to a predefined length L. A rubber profile has a cross-section that is most often, but not necessarily, rectangular in shape.

[0005] The cutting of the rubber profile to form the rubber strips can be done either upstream of the assembly process or on the assembly machine just before the rubber strip is wound onto the winding drum. After the cutting operation, the resulting rubber strip generally has a parallelepiped shape with a predefined length L, usually greater than its width and thickness. This predefined length L is such that, after winding onto the winding drum, the end faces of the rubber strip can be joined to form a single-piece ring. The parallelepiped-shaped rubber strip comprises two base faces, the edges of which define the length L and the width of the rubber strip, and two lateral faces, of which the edges delimit the length L and the thickness of the rubber band, and two end faces, whose edges delimit the thickness and the width of the rubber band, said end faces being usually called "lips".

[0006] Non-vulcanized rubber strips are generally sticky, that is to say, comprising in particular end faces having good adhesion properties, allowing the joining operation between the lips of the rubber strip to be carried out easily, said joining operation being also called "welding" and being carried out by bringing into contact and pressing together the entire surface of the end faces or lips of said rubber strip.

[0007] To facilitate the compression of the lips during welding, and also to increase the overlap area and weld adhesion, said lips are generally cut at an angle. A bevel cut is understood to be a cut that creates a lip forming a non-right angle with the base faces of the rubber strip. In some cases, the lip forms, in addition to the non-right angle with the base faces, a non-right angle with the side faces.

[0008] To improve adhesion properties, it is known to those skilled in the art to apply chemical compounds to the weld lips before the welding operation. Other known solutions involve heating the lips before welding.

[0009] Patent KR10-0987863B1 discloses a device and method for welding an unvulcanized rubber strip by heating the edges of both ends of said rubber strip using halogen or infrared lamp heating systems. The heating is carried out while the rubber strip is lying flat and still waiting on a transfer device used to transport said rubber strip to a manufacturing drum. This method does not allow for precise heating to the desired temperature and only heats the surface corresponding to the edges, as the heat generated by the heating device diffuses beyond the edges of the rubber strip. Furthermore, during the winding step of the rubber strip, the edges are no longer heated and cool down, necessitating overheating of said edges to obtain the desired temperature during the welding step.Overheating of the edges often causes a degradation of the mechanical properties of the unvulcanized rubber strip.

[0010] Application JP2022117657A discloses a system for simultaneously heating two beveled lips after they have been brought into contact on a garment-making drum. The heating is achieved by a system such as a halogen lamp or a hot air blowing system. A presser then applies pressure to the weld area to improve adhesion between the two lips. The heating solutions used do not allow for precise and exclusive heating of the contacting surfaces of the lips. The area of ​​the rubber band around The edges also undergo a temperature increase, or even overheating, to achieve the desired temperature at the level of said edges. Consequently, this type of solution requires significant heating power and can lead to degradation of the unvulcanized rubber strip.

[0011] The objects assigned to the invention therefore aim to remedy the aforementioned drawbacks and to propose, for an assembly and welding machine intended for the manufacture of a tire before curing, a device and a method for welding the lips of a rubber strip, intended to improve the adhesion of said lips without using chemical compounds and without degrading the rubber strip, the method of the invention being fast and economical.

[0012] The objects assigned to the invention are achieved by means of an assembly and welding machine intended for the manufacture of a pre-cured tire comprising: firstly, a feeding device comprising: -a unwinding station designed to unwind a rubber profile wound on a storage reel, -a transfer conveyor belt allowing the rubber profile from the storage reel to be pulled and flattened, - a cutting device intended to cut the rubber profile transversely to form a rubber strip of substantially parallelepiped shape, said rubber strip comprising end faces called respectively first and second lips and each forming an angle α with a base face of said rubber strip, secondly a manufacturing device comprising: -a structure fixed to the ground, -a sewing drum, supported by the frame and motorized in rotation, said rotation allowing the rubber band to be wound onto said sewing drum so as to overlap the first and second lips respectively, said wound rubber band having an outer surface not in contact with the sewing drum, said assembly and welding machine being characterized in that it comprises: thirdly, a welding device comprising: -a hot blade, having at least one first face and a second face and two lateral edges, -a heating system to heat the hot blade, -an actuator enabling, on the one hand, the insertion of said hot blade between the first and second lips of the wound rubber strip, said insertion being made in a direction substantially parallel to the first and second lips of the rubber strip, and, on the other hand, the removal of said hot blade following a direction substantially parallel to the first and second lips of the rubber strip respectively, -a pressure mechanism comprising a pressure actuator and a pressure pad having an end surface, said pressure pad being intended to press on the outer surface of the wound rubber strip, the pressure of said pressure pad being made in a direction F allowing to make contact on the one hand the first lip with the second face of the hot blade and the second lip with the first face of the hot blade, when said hot blade is inserted and, on the other hand, the first lip with the second lip when the hot blade is removed.

[0013] Essentially, the assembly and welding machine according to the invention makes it possible to produce a rubber torus with a continuous and good quality weld over the entire surface of the lips of a rubber strip, while avoiding thermal degradation of said rubber strip.

[0014] In one embodiment, the first and second faces of the hot blade are parallel to each other, thus allowing the hot blade to be inserted or removed easily without deforming the first and second lips of the rubber strip.

[0015] Advantageously, the first face of the hot blade forms with the second face of the hot blade an angle having a value greater than 0 degrees and at most equal to 20 degrees and preferably having a value greater than 5 degrees and at most equal to 10 degrees.

[0016] The presence of an angle between the first and second faces of the hot blade respectively improves the contact between said first and second faces of the hot blade and the second and first lips respectively, even when said second and first lips respectively are not parallel at the end of winding the rubber strip onto the making drum.

[0017] Advantageously, a mean blade plane passing between the first face of the hot blade and the second face of the hot blade is parallel to the direction of insertion and withdrawal of said hot blade.

[0018] The parallelism between the average blade plane and the insertion and withdrawal direction makes it easier to insert and withdraw the hot blade.

[0019] Even more advantageously, the average blade plane passing between the first face of the hot blade and the second face of the hot blade forms with the insertion direction of said hot blade an angle having a value greater than 0 degrees and at most equal to 20 degrees and preferably having a value greater than 5 degrees and at most equal to 10 degrees.

[0020] As before, the angle between the mean blade plane and the insertion and withdrawal direction improves the contact between said blades respectively. first and second faces of the hot blade and the respective first and second lips, even when said respectively first and second lips are not parallel at the end of winding the rubber band onto the making drum.

[0021] Advantageously, the maximum distance between the first and second faces of the hot blade is between 0.5 mm and 30 mm, and preferably between 1 mm and 5 mm. This small distance between the first and second faces of the hot blade allows the hot blade to be inserted between the first and second lips that have not yet been welded without risk of deformation of the rubber strip.

[0022] In a particular embodiment of the invention, the first and second faces of the hot blade respectively comprise longitudinal grooves oriented in a direction parallel on the one hand to the first and second faces of the hot blade respectively and on the other hand in a direction parallel to the lateral edges of said hot blade.

[0023] The longitudinal grooves thus increase the contact area between the first and second faces of the hot blade and the second and first lips, respectively, when the hot blade is inserted between the second and first lips. After the hot blade is withdrawn, the surfaces of the first and second lips are deformed and include longitudinal grooves. These longitudinal grooves of the first lip are designed to cooperate with the longitudinal grooves of the second lip when the first and second lips are brought into contact. The increased contact area between the first and second lips results in a larger weld area and therefore improved weld pull-out resistance.

[0024] Preferably, the heating system is a heating system integrated into the hot blade, said integrated heating system being, for example and not exhaustively, an electric heating wire, an electric heating pencil, or a heating system by hot fluid circulation, these solutions allowing good temperature regulation accuracy at the level of the first and second faces of the hot blade respectively, while allowing heating of the hot blade even when it is inserted between the first and second lips respectively.

[0025] In one embodiment, the heating system is an independent heating system, which may be, for example and without limitation, an electric oven, a gas oven, a hot air blower or an infrared radiation device, these solutions allowing the blade to be heated simply and economically, even when said blade is of small thickness.

[0026] Advantageously, the end surface of the pressure pad has a geometry that allows it to fit the outer surface of the wound rubber strip, such a geometry making it possible to avoid the risk of deformation of the rubber strip when the pressure pad presses against the outer surface of said rubber strip.

[0027] Even more advantageously, the support direction F of the pressure pad is a radial direction to the axis of rotation of the sewing drum, thus limiting the risks of slippage of the rubber band wound on the sewing drum when the pressure pad is pressed.

[0028] The invention also relates to a method of implementing the assembly and welding machine described above and characterized by the following steps: -rotation of the storage reel and simultaneous start-up of the transfer conveyor to unwind the rubber profile onto the transfer conveyor, -Activation of the cutting device to cut the rubber profile transversely and form the rubber strip, -rotation of the storage reel, simultaneous start-up of the transfer conveyor to unwind the rubber profile onto the transfer conveyor, and simultaneously, rotation of the assembly drum to wind the rubber strip onto said assembly drum so as to overlap the first lip with the second lip, -activation of the hot blade heating system to obtain a temperature T at the level of the first and second faces of said hot blade, respectively, -insertion of the hot blade between the first and second lips of the rubber strip, said insertion being made in a direction substantially parallel to said first and second lips of the rubber strip, respectively -activation of the pressure mechanism for a duration DI in order to press the pressure pad of the pressure mechanism on the outer surface of the wound rubber strip, the pressure of said pressure pad being made in the direction F, the pressure of said pressure pad being made with a pressure PI allowing on the one hand the first face of the hot blade to be in contact with the second lip of the rubber strip and on the other hand, the second face of the hot blade to be in contact with the first lip of the rubber strip, -deactivation of the pressure mechanism at the end of the DI duration and simultaneously, removal of the hot blade and deactivation of the heating system, -activation of the pressure mechanism to press the pressure pad against the outer surface of the wound rubber strip, the pressure of said pressure pad being following the direction F, the support of said pressure pad being made with a pressure P2 allowing the first lip to be brought into contact in compression with the second lip, said activation of the pressure mechanism being made for a duration D2 during which the first and second lips respectively cool down, -deactivation of the pressure mechanism and removal of the pressure pad, -evacuation of the welded rubber strip and start of a new assembly and welding cycle on the sewing drum.

[0029] Heating the first and second faces of the hot blade to a temperature T, combined with bringing said first and second faces into contact with the second and first lips respectively when the pressure pad is pressed, ensures uniform contact, thus guaranteeing good homogeneity and precise control of the amount of heat transferred to the first and second lips. The resulting weld is therefore of good quality, and the rubber strip is not damaged by potential overheating.

[0030] Advantageously, after the removal of the hot blade, the support of said pressure pad along the direction F allows for pressure cooling which improves the quality of the weld, even with rubber strips having low level adhesion properties.

[0031] Advantageously, the temperature T is between 60 and 260 degrees Celsius, and preferably between 120 and 200 degrees Celsius, in order to avoid overheating and, consequently, any degradation of the rubber strip, while ensuring a modification of the rubber strip's properties that improves adhesion and thus guarantees a good quality weld. The temperature T is expressed in degrees Celsius.

[0032] Advantageously, the pressure PI is between 0.05 N / mm2 and 1 N / mm2 and preferably between 0.1 N / mm2 and 0.5 N / mm2, thus ensuring good contact and better heat transmission between the first and second faces of the hot blade and the second and first lips respectively.

[0033] Preferably, the duration DI is between 2 seconds and 60 seconds and even more preferably between 10 seconds and 30 seconds, the control of this duration DI making it possible to heat only the surface of the first and second lips respectively over a very shallow depth, thus limiting the need for energy and avoiding any risk of local overheating.

[0034] Advantageously, the pressure P2 is between 0.05 N / mm2 and 1 N / mm2 and preferably between 0.1 N / mm2 and 0.5 N / mm2, thus ensuring good contact between the first and second lips respectively during the cooling of the weld, said good contact consequently generating a perfect weld over the entire contact surface between said first and second lips respectively.

[0035] Preferably, the duration D2 is between 2 seconds and 60 seconds and preferably between 10 seconds and 30 seconds, the control of this duration ensuring an optimized cooling time under pressure, thus shortening the overall cycle time of the weld.

[0036] The invention also relates to a pre-baked tire manufactured according to the implementation process of the assembly and welding machine of the invention.

[0037] Other objects, features and advantages of the invention will become apparent in more detail from the reading of the detailed description that follows, as well as with the aid of the figures attached and provided for purely illustrative and non-limiting purposes.

[0038] Fig. 1 illustrates, according to a front projection view, an assembly and welding machine according to the invention.

[0039] Fig. 2 is a top view of the assembly and welding machine according to the invention.

[0040] Fig. 3 is a front projection view of the assembly and welding machine at the stage of unwinding and flattening the rubber profile onto the transfer conveyor.

[0041] Fig. 4 represents, according to a front projection view, the assembly and welding machine at the rubber profile cutting stage.

[0042] Fig. 5 is a front projection view of the assembly and welding machine at the stage comprising unwinding and flattening the rubber profile and simultaneously winding the rubber strip onto the making drum.

[0043] Fig. 6 illustrates, according to a front projection view, the assembly and welding machine when the rubber strip is completely wound onto the making drum.

[0044] Fig. 7 is a detailed front projection view of the first and second overlapping lips respectively at the end of the rubber strip winding step and before the insertion of the hot blade.

[0045] The [Fig.8] is a detailed front projection view of the welding device at the welding area with the hot blade inserted between the first and second lips respectively.

[0046] Fig. 9 represents a detailed front projection view of the welding device at the welding area with the hot blade inserted between the first and second lips respectively and the pressure pad applied to the outer surface of the wound rubber strip.

[0047] Fig. 10 illustrates, in a detailed view and front projection, the welding device at the welding area with the hot blade removed and the pressure pad applied to the outer surface of the wound rubber strip.

[0048] Fig. 11 is a detailed front projection view of the welding device. level of the weld zone when the weld is finished with the hot blade and the presser removed.

[0049] Fig. 12 is a perspective view of a rubber strip laid flat.

[0050] Figure 13 is a detailed side view of a hot blade comprising first and second faces not parallel.

[0051] Fig. 13a is a partial and perspective view of the hot blade according to the particular embodiment in which the hot blade includes longitudinal grooves.

[0052] Fig. 13b is a detailed cross-sectional view of the hot blade according to the particular embodiment in which the hot blade includes longitudinal grooves, the cut being made along a plane perpendicular to the direction of insertion of the hot blade between the first and second lips respectively.

[0053] In what follows, the terms "top", "bottom", "lower", "upper" and their variants shall be understood with reference to the vertical direction of the figures. The value ranges defined by the terms "between a and b" encompass the values ​​a and b.

[0054] The invention relates to an assembly and welding machine 100.

[0055] As can be seen in [Fig. 1], the assembly and welding machine 100 comprises a feeding device 200, a making device 300 and a welding device 400.

[0056] The power supply device 200 comprises: -a unwinding station 10 intended for unwinding a rubber profile 8 wound on a storage reel 11, -a transfer conveyor 2 allowing the rubber profile 8 from the storage reel 11 to be pulled and flattened, -a cutting device 6 intended to cut transversely the rubber profile 8, to form a rubber strip 7 of substantially parallelepiped shape, said rubber strip 7 comprising end faces called respectively first and second lips 7a, 7b and each forming an angle a with a base face 7c of said rubber strip 7.

[0057] As is known to those skilled in the art, the rubber profile 8 is produced upstream, using, for example, extrusion or calendering machines and processes.

[0058] The storage reel 11 may be a reel comprising a central hub and side walls for holding the rubber profile 8 wound on the reel in position. Other storage means are known to those skilled in the art. They can also be used, for example, as means of storing rubber profiles on trays.

[0059] As illustrated in [Fig. 1], the unwinding station 10 is a motorized roller system on which the storage reel 11 rests. The rotation of the rollers ensures the rotation of the storage reel 11 and the unwinding of the rubber profile 8. Any other unwinding device conventionally known to those skilled in the art may also be used, such as, for example, a device with a rotating axis, said rotating axis serving to support and rotate the reel by its center.

[0060] As can be seen in Figures 1 and 2, the cutting device 6 is a blade device placed above the transfer mat 2, the width of the blade of said blade device being greater than the width of the rubber profile 8, thus allowing a cutting of said rubber profile 8 in a single actuation of the cutting device 6 to form the rubber strip 7 of length L, said length L being able to be defined as the largest longitudinal dimension of the base faces of the rubber strip 7.

[0061] Any other rubber profile 8 cutting device 6 can also be used, such as, for example, rotary circular blade cutting devices or ultrasonic cutting devices.

[0062] The angle a formed between the first and second lips 7a, 7b respectively and the base face 7c has a value generally between 20 and 60 degrees and preferably between 30 and 45 degrees.

[0063] The 300 assembly device comprises: -a frame 17 fixed to the ground, -a making drum 1, supported by the frame 17 and motorized in rotation, said rotation allowing the rubber band 7 to be wound on said making drum 1 so as to superimpose the first and second lips 7a, 7b respectively, said wound rubber band 7 having an outer surface 14 not in contact with the making drum 1 and as seen in figures 6 and 7, the first lip 7a being the closest radially to the making drum 1, and the second lip 7b being the furthest from the making drum 1.

[0064] As shown in Figures 5 and 6, the rubber strip 7 can be wound directly onto the making drum 1, or, in other cases not shown, the rubber strip 7 is wound onto other rubber elements already present on the making drum 1, said rubber elements being, for example, strips or plies used in the making of a tire casing.

[0065] Depending on the support onto which the rubber strip 7 is wound (either directly onto the garment drum 1 or onto other rubber elements), the length L of said rubber strip 7 is adjusted accordingly, thus allowing the first lip 7a to overlap the second lip 7b when the rubber strip 7 is completely wound. Therefore, the length L corresponds either to the perimeter of the outer face of the garment drum 1 or to the perimeter of the outer face of the last rubber element previously wound onto the garment drum 1.

[0066] The welding device 400 comprises, as shown in Figures 1 and 8: - a hot blade 5, having at least a first face 5a and a second face 5b, and two lateral edges, -a heating system 4 for heating the hot blade 5, -an actuator 15 allowing on the one hand the insertion of said hot blade 5 between the respectively first and second lips 7a, 7b of the wound rubber strip 7, said insertion being made in a direction substantially parallel to the respectively first and second lips 7a, 7b of the rubber strip 7 and, on the other hand, the withdrawal of said hot blade 5 in a direction substantially parallel to the respectively first and second lips 7a, 7b of the rubber strip 7, -a pressure mechanism 18 comprising a pressure actuator 13 and a pressure pad 19 having an end surface 20, said pressure pad 19 being intended to press on the outer surface 14 of the wound rubber strip 7, the pressure of said pressure pad 19 being made in a direction F allowing to be in contact on the one hand the first lip 7a with the second face 5b of the hot blade 5 and the second lip 7b with the first face 5a of the hot blade 5, when said hot blade 5 is inserted and, on the other hand, the first lip 7a with the second lip 7b when the hot blade 5 is removed.

[0067] As can be seen in [Fig.7], at the end of the winding of the rubber strip 7 and before any action of the hot blade 5 or the pressing mechanism 18, the first and second lips 7a,7b respectively are superimposed but are not perfectly applied to each other, areas of the surface of the first lip 7a not being in contact with the second lip 7b, this perfect non-contact thus allowing the insertion of the hot blade 5 between the first and second lips 7a, 7b respectively without deformation or curling of said first and second lips 7a, 7b respectively.

[0068] With reference to [Fig. 2], the hot blade 5 has a blade width L1 which is greater than or equal to the band width L2 of the rubber band 7, allowing the first face 5a to be in contact over the entire width of the second lip 7b and on the other hand, the second face 5b is to be in contact over the entire width of the first lip 7a when the hot blade 5 is inserted between said first and second lips 7a, 7b respectively.

[0069] By insertion along a direction substantially parallel to the first and second lips 7a, 7b respectively, and as illustrated by [Fig.7], it is necessary to understand a direction of insertion or withdrawal of the hot blade 5 forming an angle of less than five degrees with a mean plane G passing between the first and second lips 7a, 7b respectively.

[0070] By mean plane G, it is necessary to understand a plane comprising a maximum of midpoints, said midpoints being the points located in the middle of segments perpendicular to said mean plane G, said perpendicular segments having as their first endpoint a point of the first lip 7a and as their other endpoint a point of the second lip 7b.

[0071] In one embodiment, the first and second faces 5a, 5b of the hot blade 5 are parallel to each other.

[0072] Advantageously, the first face 5a of the hot blade 5 forms with the second face 5b of the hot blade 5 an angle having a value greater than 0 degrees and at most equal to 20 degrees and preferably having a value greater than 5 degrees and at most equal to 10 degrees.

[0073] Advantageously, a mean blade plane G1 passing between the first face 5a of the hot blade 5 and the second face 5b of the hot blade 5 is parallel to the insertion and withdrawal direction of said hot blade 5. As can be seen in [Fig. 13], the mean blade plane G1 is the plane comprising a maximum of midpoints, said midpoints being the points located at the midpoints of segments perpendicular to said mean plane G1, said perpendicular segments having as their first endpoint a point on the first face 5a and as their other endpoint a point on the second face 5b.

[0074] Even more advantageously, the average blade plane Gl passing between the first face 5 a of the hot blade 5 and the second face 5b of the hot blade 5 forms with the insertion direction of said hot blade 5 an angle having a value greater than 0 degrees and at most equal to 20 degrees and preferably having a value greater than 5 degrees and at most equal to 10 degrees.

[0075] Advantageously, the maximum distance between the first and second faces 5a, 5b of the hot blade 5 is between 0.5 mm and 30 mm and preferably between 1 mm and 5 mm.

[0076] In another embodiment, and as shown in Figures 13a and 13b, the first and second faces 5a, 5b respectively of the hot blade 5 comprise longitudinal grooves 5c. These longitudinal grooves 5c are obtained by making notches at the level of the first and second faces 5a, 5b of the hot blade 5 respectively, said longitudinal grooves 5c being oriented in a direction parallel on the one hand to the first and second faces 5a, 5b of the hot blade 5 respectively and on the other hand in a direction parallel to the lateral edges of said hot blade 5.

[0077] The longitudinal grooves 5c may be present in part or on all of the first and second faces 5a, 5b respectively.

[0078] As can be seen in [Fig. 13b], the longitudinal grooves 5c may have triangular cross-sections. In other, unclaimed embodiments, the longitudinal grooves 5c may have other cross-sectional shapes, such as, for example, but not limited to, square, rectangular, or rounded shapes.

[0079] By way of example, the depth of the longitudinal grooves 5c can be between 10% and 20% of the smallest distance between the first face 5a and the second face 5b.

[0080] Furthermore, the first and second faces 5a, 5b of the hot blade 5 can respectively include an anti-adhesion coating of the fluoropolymer type such as polytetrafluoroethylene (PTFE), perfluoroalkoxy (PFA) or fluorinated ethylene propylene (FEP).

[0081] The small distance between the first and second faces 5a, 5b respectively, as well as the presence of an anti-stick coating, allows the hot blade 5 to be inserted between the first and second faces 5a, 5b respectively without deforming or curling said first and second faces 5a, 5b respectively.

[0082] The actuator 15 may be, by way of example and in a non-exhaustive manner, a Cartesian robot, a multi-articulated robot, or a mechanical device with pneumatic cylinders, electric cylinders or electromagnetic cylinders.

[0083] Preferably, the heating system 4 is a heater integrated into the hot blade 5, said heating system 4 being, for example and in a non-exhaustive manner, an electric heating wire, an electric heating pencil, or a hot fluid circulation heater.

[0084] In one embodiment, not shown, the heating system 4 is an independent heating device which may be, by way of example and without limitation, an electric oven, a gas oven, a hot air blower, or an infrared radiation device. In this embodiment, the hot blade 5 is heated to a temperature T by being placed by the actuator 15 in the electric or gas oven, or near the hot air blower or the infrared radiation device. Since the hot blade 5 has good thermal inertia, the temperature of the first and second faces 5a, 5b respectively remains close to temperature T during the insertion step of said hot blade 5 between the first and second faces 7a, 7b respectively.

[0085] The press actuator 13 of the press mechanism 18 may be, by way of example and in a non-exhaustive manner, a Cartesian robot, a multi-articulated robot, or a mechanical device with pneumatic cylinders, electric cylinders or electromagnetic cylinders.

[0086] Advantageously, the end surface 20 of the pressure pad 19 has a geometry that allows it to conform to the outer surface 14 of the wound rubber strip 7. As illustrated in Figures 9 to 11, which are front projection views, the end surface 20 has a curved shape with a radius equivalent to the radius of the outer surface 14 of the wound rubber strip 7, this curved shape being constant over the entire width L3 of the pressure pad 19. As shown in [Fig. 2], the pressure pad 19 also has a width L3 that is greater than or equal to the width L2 of the rubber strip 7, thus allowing the pressure pad 19 to bear down over the entire width L2 of the rubber strip 7.

[0087] The pressure pad 19 of the pressure mechanism 18 can be, for example, made of steel, stainless steel, hard plastic or any other rigid material.

[0088] Alternatively, the pressure pad 19 of the pressure mechanism 18 may be, for example, made of soft plastic, rubber or any other soft material, this type of material allowing it to perfectly conform to the shape of the rubber band 7 when said pressure pad 19 is pressed.

[0089] In other unclaimed embodiments, the pressure mechanism 18 comprises a plurality of pressure actuators 13 cooperating with a plurality of pressure pads 19, each of said pressure pads 19 having a width less than the band width L2, each of said pressure pads 19 being juxtaposed with another pressure pad 19, each of said pressure pads 19 being intended to press on the outer surface 14 of the rubber band 7, and said pressure pads 19 exerting pressure in parallel directions. In such embodiments, the sum of the widths of the plurality of pressure pads 19 is greater than the band width L2, said plurality of pressure pads 19 thus being able to press on the entire width of the outer surface 14. Preferably, the pressure actuators 13 are preferably compact pneumatic cylinder-type actuators.

[0090] The use of a plurality of pressure pads 19 also allows for more homogeneous, regular and precise pressing on the outer surface 14.

[0091] Advantageously and as represented by figures 7 to 10, the support direction F of the pressure pad 19 is a radial direction to the axis of rotation of the garment drum 1.

[0092] The invention also relates to a method of implementing the assembly and welding machine 100 as defined above.

[0093] As seen in [Fig.3], the first step of the process consists of rotating the storage reel 11 and simultaneously starting the transfer conveyor 2 to unwind the rubber profile 8 onto the transfer conveyor 2.

[0094] When the desired length L of the rubber profile 8 is laid flat on the transfer conveyor 2, the rotation of the storage reel 11 and the scrolling of the transfer conveyor 2 are stopped.

[0095] As illustrated in [Fig.4], the process includes a second step in which the cutting device 6 is actuated to cut the rubber profile 8 transversely and form, as seen in [Fig. 12], the rubber strip 7 having as end faces the first and second lips 7a, 7b respectively and as lower face the base face 7c.

[0096] The third step of the process, represented by figures 5 and 6, includes the rotation of the storage reel 11, the simultaneous start-up of the transfer conveyor 2 to unwind the rubber profile 8 onto the transfer conveyor 2, and, still simultaneously, the rotation of the making drum 1 in order to wind the rubber strip 7 onto the making drum 1 so as to superimpose the first lip 7a onto the second lip 7b.

[0097] The process includes a fourth step which consists of activating the heating system 4 of the hot blade 5 in order to obtain a temperature T at the level of the first and second faces 5a, 5b of said hot blade 5 respectively.

[0098] In some embodiments, this fourth step can be done simultaneously with the third step, thus saving cycle time without prejudice to the quality of the weld performed.

[0099] In other embodiments, the heating of the hot blade5 to temperature T is carried out continuously throughout the welding cycle.

[0100] As shown in [Fig.8], a fifth step of the process is carried out by inserting the hot blade 5 between the first and second lips 7a, 7b of the rubber strip 7 respectively, said insertion being made in a direction substantially parallel to said first and second lips 7a, 7b of the rubber strip 7 respectively.

[0101] Thanks to the thinness of the hot blade 5, the insertion of said hot blade 5 between the first and second lips 7a, 7b respectively is carried out without deformation or deterioration of the rubber strip 7.

[0102] As illustrated by [Fig. 9], the method includes a sixth step in which the pressure mechanism 18 is activated for a duration DI in order to press the pressure pad 19 of the pressure mechanism 18 against the outer surface 14 of the belt. rubber 7 wound, the support of said pressure pad 19 being made in the direction F previously defined, the support of said pressure pad 19 being made with a pressure PI allowing on the one hand the first face 5a of the hot blade 5 to be in contact with the second lip 7b of the rubber strip 7 and on the other hand, the second face 5b of the hot blade 5 to be in contact with the first lip 7a of the rubber strip 7.

[0103] A seventh step of the process is represented by [Fig. 10] and includes the deactivation of the pressure mechanism 18 at the end of the duration DI and simultaneously, the removal of the hot blade 5 and the deactivation of the heating system 4. The deactivation of the pressure mechanism 18 reduces the support pressure of the pressure pad 19 to a zero value, which makes it easier to remove the hot blade 5, the friction of the respectively first and second faces 5a, 5b of the hot blade 5 against respectively the second and first lips 7b, 7a being less important.

[0104] In some embodiments, the heating system 4 is not deactivated during the seventh step of the process and remains permanently activated during all steps of the process.

[0105] During an eighth step, the pressure mechanism 18 is again activated to press the pressure pad 19 against the outer surface 14 of the wound rubber strip 7, the pressure of said pressure pad 19 being made in the direction F, the pressure of said pressure pad 19 being made with a pressure P2 allowing the first lip 7a to be brought into contact under compression with the second lip 7b, said activation of the pressure mechanism 18 being made for a duration D2 during which the first and second lips 7a, 7b respectively cool down.

[0106] As shown in [Fig.1 1], the process includes a ninth step in which the presser mechanism 18 is deactivated and the presser pad 19 is removed.

[0107] The last step of the process, not shown, includes the evacuation of the welded rubber strip 7 to a downstream process for making a tire, thereby freeing the making drum 1 and allowing the start of a new assembly and welding cycle on the making drum 1.

[0108] Advantageously, the temperature T is between 60 degrees and 260 degrees and preferably between 120 degrees and 200 degrees. The temperature T is expressed in degrees Celsius.

[0109] Advantageously, the PI pressure is between 0.05 N / mm2 and 1 N / mm2 and preferably between 0.1 N / mm2 and 0.5 N / mm2.

[0110] Even more advantageously, the duration D1 is between 2 seconds and 60 seconds and preferably between 10 seconds and 30 seconds.

[0111] Advantageously, the pressure P2 is between 0.05 N / mm2 and 1 N / mm2 and preferably between 0.1 N / mm2 and 0.5 N / mm2.

[0112] Preferably, the duration D2 is between 2 seconds and 60 seconds and preferably between 10 seconds and 30 seconds.

[0113] The device of the invention is particularly suitable for welding slightly sticky rubber strips 7.

[0114] The term "stickiness" defines a property of a rubber compound that varies depending on the compound formulation. As known to those skilled in the art, the "stickiness" of a rubber compound can be related, for example, to the nature of the elastomer, the ratio between the filler content and the plasticizer content, or the tackifying resin content in the compound. For some compositions, the level of stickiness is so low that it is impossible to obtain, on the one hand, adhesion over the entire surface of the first and second lips 7a, 7b respectively, and on the other hand, a durable adhesion that would allow for a perfect weld until the vulcanization stage.

[0115] Depending on the level of stickiness, the various parameters of the process of the invention, i.e., the values ​​of temperature T, pressures PI, P2, and durations D1, D2, will be adjusted to obtain a good quality weld with the shortest and most economical cycle time possible. For certain rubber strips 7 with sufficiently high stickiness, the fifth, sixth, and seventh steps of the process of the invention will not be carried out.

[0116] One cycle of the welding process of the invention can be carried out by controlling a programmable logic controller (PLC) and can include pre-programming of the various parameters. For example, depending on the stickiness level of a rubber strip 7, a setting of the process parameters can be associated with the type of rubber strip 7.

[0117] The different pre-programming of the different parameters according to the level of stickiness of the rubber strips 7 can be obtained by carrying out, for example, preliminary tests on the assembly and welding machine 100 or by using numerical simulation, self-learning or artificial intelligence techniques.

[0118] In an embodiment not shown and not claimed, small temperature sensors, for example thermocouple wires, can be inserted and brought into contact with the first and second lips 7a, 7b respectively during steps 6 and 8 of the welding and assembly process. In such an embodiment, the durations D1 and D2 are no longer defined by prior testing or by self-learning or artificial intelligence techniques, but by monitoring, by the PLC, of ​​the evolution of the surface temperature of the first and second lips 7a, 7b respectively, said evolution being a function of time. Thus, during step 6, when the desired surface temperature of the first and When the second lip temperature (7a, 7b) is reached, the PLC triggers the transition to the next step. Similarly, in step 8, when the desired surface cooling temperature of the first and second lips (7a, 7b) is reached, the PLC triggers the transition to the ninth step. In this embodiment, only the temperature thresholds to be reached in steps 6 and 8 are defined by trials or by self-learning or artificial intelligence techniques.

[0119] Tests were carried out to compare the method of the invention with a method known to those skilled in the art. To carry out the tests, test pieces of the same rubber, 50 mm wide and 22 mm thick, were cut. Beveled edges were formed at one end of each test piece. The test pieces were then welded together in pairs at their edges using different settings for different welding processes.

[0120] Table 1 below shows the parameter settings for a welding process as known to those skilled in the art. The heating of the lips is carried out using an infrared heating device, which heats the beveled lips of the rubber test pieces before the welding operation. The test pieces are made of a rubbery material, hereinafter referred to as "Recipe 1," the composition of which corresponds to the composition Tl as described in Table 1 of application WO2023 / 088813A1. To simulate the winding time on a manufacturing drum 1, a waiting period is observed before welding the lips of the test pieces. [Tables 1] Parameter settings Test piece by IR heating Material type Recipe 1 Heating temperature 150°C Waiting time before welding 10s IR heating time 30s Pressure 100m² / mm² Time under pressure 20s Total cycle time 60s

[0121] Table 2 below shows the settings used for implementing the process of the invention according to two embodiments. [Tables 2] Parameter settings Manufacturing mode 1 Manufacturing mode 2 Material type Recipe 1 Recipe 1 Temperature T 100°C 150°C Pressure P1 10N / mm² 10N / mm² Duration DI 30s 10s Pressure P2 10N / mm² 10N / mm² Duration D2 25s 20s Welding cycle time 55s 30s

[0122] After welding the various test specimens, the test consists of measuring the maximum force required to separate the two previously welded edges. To do this, the unbeveled ends of the specimens are clamped between two pairs of jaws of an Instron-type tensile testing machine. The machine then spreads the jaws apart, allowing a progressively applied tensile force to be applied until the edges separate.

[0123] Table 3 below allows comparison of the maximum tensile force obtained to detach the lips of the test specimens during the different tests. [Tables 3] Witness with weld made by IR heating of the lips. Weld made according to embodiment 1. Weld made according to embodiment 2. Maximum tensile force to separate the lips: 15N, 21N, 23N

[0124] The results obtained show that welds made according to the embodiments of the invention make it possible to obtain a maximum tensile force greater than that obtained during the test with the control, by at least 30%.

[0125] The invention also relates to a pre-cured tire manufactured according to the process of the invention implementing the assembly and welding machine of the invention.

Claims

1. Demands Assembly and welding machine (100) for manufacturing a pre-cured tire comprising: firstly, a feeding device (200) comprising: - an unwinding station (10) for unwinding a rubber profile (8) wound on a storage reel (11), - a transfer conveyor (2) for pulling and flattening the rubber profile (8) from the storage reel (11), - a cutting device (6) for cutting the rubber profile (8) transversely to form a rubber strip (7) of substantially parallelepiped shape, said rubber strip (7) comprising end faces called respectively first and second lips (7a, 7b) and each forming an angle α with a base face (7c) of said rubber strip (7), secondly, a manufacturing device (300) comprising: - a frame (17) fixed to the floor, -a making drum (1), supported by the frame (17) and motorized in rotation, said rotation allowing the rubber strip (7) to be wound onto said making drum (1) so as to overlap the first and second lips (7a, 7b) respectively, said wound rubber strip (7) having an outer surface (14) not in contact with the making drum (1), the assembly and welding machine (100) being characterized in that it comprises: thirdly a welding device (400) comprising: -a hot blade (5), having at least a first face (5a) and a second face (5b) and two lateral edges, -a heating system (4) for heating the hot blade (5), -an actuator (15) allowing, on the one hand, the insertion of said hot blade (5) between the first and second lips (7a, 7b) of the wound rubber strip (7), said insertion being made in a direction substantially parallel to the first and second lips (7a, 7b) of the rubber strip (7), and, on the other hand, the withdrawal of said hot blade (5) in a direction substantially parallel to the first and second lips (7a, 7b) of the rubber strip (7), respectively, -a pressure mechanism (18) comprising a pressure actuator (13) and a pressure pad (19) having an end surface (20), said pressure pad (19) being intended to press on the outer surface (14) of the wound rubber strip (7), the pressure of said pressure pad (19) being made in a direction F allowing to be brought into contact on the one hand the first lip (7a) with the second face (5b) of the hot blade (5) and the second lip (7b) with the first face (5a) of the hot blade (5), when the hot blade (5) is inserted and, on the other hand the first lip (7a) with the second lip (7b) when the hot blade (5) is removed.

2. Assembly and welding machine (100) according to claim 1 in which the first and second faces (5a, 5b) of the hot blade (5) are parallel to each other.

3. Assembly and welding machine (100) according to claim 1 in which the first face (5a) of the hot blade (5) forms with the second face (5b) of the hot blade (5) an angle having a value greater than 0 degrees and at most equal to 20 degrees and preferably having a value greater than 5 degrees and at most equal to 10 degrees.

4. Assembly and welding machine (100) according to any one of claims 1 to 3 in which a mean blade plane (Gl) passing between the first face (5a) of the hot blade (5) and the second face (5b) of the hot blade (5) is parallel to the insertion and withdrawal direction of said hot blade (5).

5. Assembly and welding machine (100) according to any one of claims 1 to 3 in which the mean blade plane (Gl) passing between the first face (5a) of the hot blade (5) and the second face (5b) of the hot blade (5) forms with the insertion direction of said hot blade (5) an angle having a value greater than 0 degrees and at most equal to 20 degrees and preferably having a value greater than 5 degrees and at most equal to 10 degrees.

6. Assembly and welding machine (100) according to any one of claims 1 to 5 wherein the maximum distance between the first and second faces (5a, 5b) of the hot blade (5) is between 0.5 mm and 30 mm and preferably between 1 mm and 5 mm.

7. Assembly and welding machine (100) according to any one of claims 1 to 6 wherein the first and second faces (5a, 5b) of the hot blade (5) respectively comprise longitudinal grooves (5c) oriented in a direction parallel on the one hand to the first and second faces (5a, 5b) of the hot blade (5) respectively and on the other hand in a direction parallel to the lateral edges of said hot blade (5).

8. Assembly and welding machine (100) according to any one of the preceding claims 1 to 7 wherein the heating system (4) is a heater integrated into the hot blade (5).

9. Assembly and welding machine (100) according to claim 8 in which the integrated heating system (4) is an electric heating wire, an electric heating pencil, or a hot fluid circulation heater.

10. Assembly and welding machine (100) according to any one of claims 1 to 7 wherein the heating system (4) is an independent heater.

11. Assembly and welding machine (100) according to claim 10 in which the independent heating system (4) is an electric furnace, a gas furnace, a hot air blower or an infrared radiant device.

12. Assembly and welding machine (100) according to any one of claims 1 to 11 wherein the end surface (20) of the pressure pad (19) has a geometry enabling it to fit the outer surface (14) of the wound rubber strip (7).

13. Assembly and welding machine (100) according to any one of claims 1 to 12 wherein the support direction F of the pressure pad (19) is a radial direction to the axis of rotation of the garment drum (1).

14. Assembly and welding method employing an assembly and welding machine (100) according to any one of claims 1 to 13, characterized by the following steps: - rotation of the storage reel (11) and simultaneous start-up of the transfer conveyor (2) to unwind the rubber profile (8) onto the transfer conveyor (2), - actuation of the cutting device (6) to cut the rubber profile (8) transversely and form the rubber strip (7), -rotation of the storage reel (11), simultaneous start-up of the transfer conveyor (2) to unwind the rubber profile (8) onto the transfer conveyor (2), and simultaneously, rotation of the making drum (1) to wind the rubber strip (7) onto said making drum (1) so as to overlap the first lip (7a) with the second lip (7b), -activation of the heating system (4) of the hot blade (5) in order to obtain a temperature T at the level of the first and second faces (5a, 5b) of said hot blade (5), respectively -insertion of the hot blade (5) between the first and second lips (7a, 7b) of the rubber strip (7), said insertion being made in a direction substantially parallel to said first and second lips (7a, 7b) of the rubber strip (7), -activation of the pressure mechanism (18) for a duration DI in order to press the pressure pad (19) of the pressure mechanism (18) on the outer surface (14) of the wound rubber strip (7), the pressure of said pressure pad (19) being made in the direction F, the pressure of said pressure pad (19) being made with a pressure PI allowing on the one hand the first face (5a) of the hot blade (5) to be in contact with the second lip (7b) of the rubber strip (7) and on the other hand, the second face (5b) of the hot blade (5) to be in contact with the first lip (7a) of the rubber strip (7), -deactivation of the presser mechanism (18) at the end of the DI duration and simultaneously, removal of the hot blade (5) and deactivation of the heating system (4), -activation of the pressure mechanism (18) to press the pressure pad (19) against the outer surface (14) of the wound rubber strip (7), the pressure of said pressure pad (19) being in the direction F, the pressure of said pressure pad (19) being with a pressure P2 allowing the first lip (7a) to be brought into contact under compression with the second lip (7b), said activation of the pressure mechanism (18) being for a duration D2 during which the first and second lips (7a, 7b) respectively cool down, -deactivation of the pressure mechanism (18) and removal of the pressure pad (19), -evacuation of the welded rubber band (7) and start of a new assembly and welding cycle on the sewing drum (1).

15. Assembly and welding method according to claim 14, wherein the temperature T is between 60 degrees and 260 degrees and preferably between 120 degrees and 200 degrees.

16. Assembly and welding method according to claim 14 or 15, wherein the pressure PI is between 0.05 N / mm2 and 1 N / mm2 and preferably between 0.1 N / mm2 and 0.5 N / mm2.

17. Assembly and welding method according to any one of claims 14 to 16, wherein the time DI is between 2 seconds and 60 seconds and preferably between 10 seconds and 30 seconds.

18. Assembly and welding method according to any one of claims 14 to 17, wherein the pressure P2 is between 0.05 N / mm2 and 1 N / mm2 and preferably between 0.1 N / mm2 and 0.5 N / mm2.

19. Assembly and welding method according to any one of claims 14 to 18, wherein the time D2 is between 2 seconds and 60 seconds and preferably between 10 seconds and 30 seconds.

20. Pre-baking pneumatic manufactured according to a method of implementation according to claims 14 to 19 of an assembly and welding machine (100) according to any one of claims 1 to 13.

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