FR2796330A1 - Vulcanizing apparatus used for retreading pneumatic tyres, comprises mold with devices preventing air getting in between tyre walls and surface of mould cavity - Google Patents

Abstract

Vulcanizing apparatus has a press including a mould for receiving a tyre fitted with a new tread. The mould has devices preventing air getting in between the walls of the tyre and the surface of the mould cavity. An Independent claim is included for the following: (a) Retreading a used tyre using the above vulcanizing apparatus. Preferred Features: The mould may be assembled from sectors and upper and lower hub components. Each component has an air removal device at the level of the tyre rim. Each device include an outlet pipe. The devices also include a peripheral sealing joint between the upper and lower hub components.

Description

<U> <B> VULCANIZATION </ B> DEVICE FOR </ U> TIRE <U> AND </ U> <U> MANUFACTURING PROCESS <B>, </ B> </ U> The present invention relates to a vulcanization device for retreading tires. It also relates to the method of manufacturing or retreading tires associated with the vulcanization device.

Retreading of the tires is done in a conventional manner using a vulcanizing press. The principle of retreading consists in covering the tread and the sides of a used tire with raw rubber, which has been previously grated and brushed, and then vulcanizes the rubber by placing the tire in the mold of a vulcanization press. To do this, a baking chamber is provided in the tire carcass that inflates in order to press the tread and the sidewalls of the tire against the walls of the mold to allow the vulcanization of the compound by cooking.

In the prior art, tubeless presses are known for rubber vulcanization for retreading tires, however, these devices have many drawbacks related to their implementation and the quality of the retreaded tires obtained. Indeed, these devices are unsatisfactory in particular because of the problems associated with the presence of air between the sidewalls of the tire and the walls of the mold, which alters the quality of the tire thus retreaded and may even prevent its retreading. Thus, if these devices give satisfactory results in some cases, they are not likely to adapt to different types of tires and are ineffective when the bead of the tire and more specifically the lip located at the end of the tire is damaged causing damage to the tire. infiltration of air between the walls of the mold and the flanks chi tire.

Chambered devices are also known, however they have relatively long cooking cycles because of the heat loss in the cooking chamber and the distribution of the rubber and the balancing of the tire are made dependent on the shape that takes said cooking chamber in the carcass chi tire.

Also, the present invention aims to solve the aforementioned drawbacks using simple, reliable, easy to implement and inexpensive means. It thus proposes a vulcanization device for the manufacture of tires whose cycle of cooking is reduced and whose quality of the tire obtained is reinforced, and in particular by allowing a good distribution of the rubber on the tire as well as avoiding problems. due to the presence of air bubbles between the sides of the tire and the walls of the mold. The device also makes it possible to stop the vulcanization of the gum of the flanks at the level of the main sealing means described below.

Other features and advantages of the invention will become apparent from the description which follows with reference to the accompanying drawings which are given by way of non-limiting examples.

 Thus, according to its main characteristic, the vulcanization device for retreading tires of the type comprising a press body in which is disposed a mold for receiving the tire covered with rubber intended to be vulcanized is characterized in that it comprises sealing means disposed on the mold for preventing the presence of air between the sidewalls of the tire and the walls of the mold during vulcanization.

According to another characteristic of the vulcanization device of the invention, it is characterized in that the sealing means are arranged in the mold to cooperate with the end of the tire flanks in a non-worn area of the tire.

According to the preferred embodiment of the vulcanization device, the cooperation between the sealing means and the tire is effected at the rounding formed by the flanks with the tire bead.

According to a complementary characteristic of the vulcanization device, the sealing means comprise air evacuation means and / or sealing lips or edges. According to the preferred embodiment of the vulcanization device of the invention, the latter is characterized in that the air evacuation means are constituted by an evacuation groove in which are regularly distributed discharge orifices of air.

According to this embodiment, the sealing lips are constituted by the edges of the groove.

According to a complementary characteristic of the vulcanization device, the mold is constituted by the assembly of sectors and a bead formed in two parts, an upper part and a lower part each carrying sealing means of the mold.

According to another characteristic of the vulcanization device of the invention, the latter is characterized in that the mold comprises complementary sealing means intended to prevent the escape of the air located in the enclosure which it forms and it comprises at least one air inlet which allows the pressurization of the enclosure.

According to an alternative embodiment of the vulcanization device, the complementary sealing means are constituted by a peripheral seal disposed between the upper bead and the lower bead.

Furthermore, the invention also relates to the tire retreading method using a vulcanization device, this method being characterized in that it consists in a main step of pressurizing the enclosure formed by the mold by introducing air or steam directly into the enclosure.

Figures 1 to 13 illustrate the preferred embodiment of the vulcanizing device of the invention and alternative embodiments thereof.

Figure 1 illustrates the vulcanization device as a whole and the placement of the tire.

Figure 2 illustrates in perspective the upper bead and the lower bead of the mold of the vulcanizer. Figure 3 shows in perspective the lower bead of the mold. Figure 4 illustrates in perspective a detail of the lower bead.

Figure 5 illustrates in perspective the upper bead of the mold.

Figure 6 shows in cross section a tire before the vulcanization of the rubber that covers it.

Figure 7 illustrates the mold and the tire in cross section.

Figure 8 shows a detail of the mold in cross section. Figures 9a and 9b illustrate in a view similar to Figure 8 the mold and its tire respectively in the inflation phase and inflated.

Figure 10 illustrates in a view similar to Figure 8 an alternative embodiment of the mold.

Figures 11 to 13 illustrate in detail in cross section other embodiments of the mold and more particularly its heels.

The vulcanization device or press of the invention bearing the general reference (1) is intended for the retreading of used tires (2) and more particularly for the so-called partial retreading of used tires, ie the retreading where the heel (3a , 3b) of the tire (2) is retained in the state and where only the sidewalls (2b, 2c) and the tread (2a) of the tire are covered with green rubber (4) to be vulcanized as shown in FIG. figure 6.

Thus, the tire (2) is previously grated and brushed up to the plies (5) which form its carcass before being covered with rubber (4) and with the exception of its respective central extremities or heels (3a , 3b) which are kept as they, said heels comprising a rod (40) inside the rubber and lips (2d, 2e) forming a rubber tip at the end of the tire.

The vulcanizing device (1) is in the form of a press body (9) inside which is disposed a mold (6) for receiving the tire (2) covered with rubber (4) and intended for to be retreaded. The mold (6) is formed by the assembly of sectors (7), intended to trap the tread (2a) of the tire (2) and the top of its flanks (2b, 2c) and a heel (8). ), advantageously made in two parts (8a, 8b) and intended to cooperate with the central portion of the sidewalls, the beads of the tire (3a, 3b) and their lips (2d, 2e).

According to the preferred embodiment of the mold (6) of the press (1) the assembly of the sectors (7) and the upper and lower heels (8a, 8b) is formed so as to form an inner chamber (10) to the The interior of which the tire is positioned as shown in Figures 1, 7, 9a and 9b so as to be able to bias the tire against the walls of the mold by creating a pressure in the enclosure.

Once the introduction of the tire (2) and heels (8a, 8b) in the press body (9) which comprises the sectors (7) illustrated in Figure 1 carried out, air or steam is introduced under pressure in the chamber (10) while heating the assembly to obtain the vulcanization of the rubber (4) on the walls (2a, 2b, 2c) of the tire (2) that it covers.

According to the invention, the vulcanization device (1) and more precisely its mold (6), comprises sealing means (ME) intended to prevent the presence of air between the sidewalls (2b, 2c) of the tire and the walls (7, 8a, 8b) of the mold (6). To do this, these main sealing means (ME) comprise air evacuation means (11, 12) and / or sealing lips (13a, 13b).

According to the preferred embodiment of the mold (6) of the vulcanization device (1), the air evacuation means (11, 12) and the sealing lips (13a, 13b) are arranged on the walls of the mold so as to cooperate with the end of the flanks (2b, 2c) or with a portion of the heel (3a, 3b) of the tire. Thus the cooperation between the tire (2) and the main sealing means (ME) of the mold (6) is effected in a non-lost area of the tire, ie in the area of the tire which is not not covered with raw gum (4) to be vulcanized.

According to the embodiment of the invention and as shown in Figures 8, 9a and 9b this cooperation is performed at the rounding (20) formed by the sides (2b, 2c) of the tire with the heel (3a , 3b). However, it could be done on the heel above the rod for example or even to the tip of the lip of the tire without departing from the scope of the invention.

According to the variant embodiments illustrated in FIGS. 1 to 13, the heel (8) is formed of an upper bead (8a) and a lower bead (8b) each of which is in the form of a central crown (14a , 14b) extended at one of its ends by a peripheral disk (15a, 15b). The central crown (14a, 14b) is intended to cooperate with the lips (2d, 2e) which form the end of the tire (2) while the peripheral disk (15a, 15b) cooperates with the sidewalls (2b, 2c) and part of the heel (3a, 3b).

The air evacuation means (11, 12) are advantageously constituted by a peripheral groove (12) disposed on the disk (15a, b) in the vicinity of the ring (14a, b) and by the orifices (11) distributed along the groove (12) in the interior thereof. These openings (11) open out of the mold (6) as shown in Figure 8 and allow the evacuation of air between the sides (2b, 2c) of the tire and the heels (8a, 8b) when the enclosure (10) is pressurized as shown in Figures 9a and 9b.

According to the preferred embodiment of the mold (6) and as shown in Figures 4, 5 and 7, the discharge holes (11) have a large diameter such as for example equal to 3 mm to facilitate the circulation of the air between the groove (12) and the outside. Note that the flanges (13a, 13b) of the groove (12) advantageously form the sealing lips on which an unembossed portion (20) of the tire (2) collapses. Thus the air evacuation means and the sealing lips are combined and are obtained by means of a groove (12) whose shape and dimensions of the profile can be variable. However, this groove advantageously has over its entire periphery non-rounded projecting flanges forming two lateral edges (13a, 13b). It goes without saying that the air evacuation means and the lips or sealing edges could be obtained separately without departing from the protective field of the invention. Furthermore, it is important to note that the sealing lips (13a, 13b) make it possible to stop the expansion of the vulcanizer rubber (4) which covers the sidewalls of the tire.

Thus, according to the variant embodiment illustrated in FIG. 10, the sealing lips (13a, 13b) are constituted by two lateral projecting profiles forming peripheral beads bordering the groove and its air evacuation ports (11, 12). ). These protruding profiles are thus independent of the groove (12) but are advantageously arranged in the vicinity thereof. According to another variant illustrated in FIG. 13, the sealing means (ME) comprise only one lip or sealing edge (13) which is obtained by producing each of the upper or lower heels (8a, 8b) in two parts ( 16a, 16b) which have a discontinuity in their surface at their respective interfaces.

It may be noted as shown in FIG. 12 that, according to a similar embodiment, the air evacuation means can be obtained without resorting to the use of a throat pierced with an orifice but thanks to an evacuation slot. (17) disposed between the two parts (16a, 16b) each forming upper and lower heels (8a, 8b) and formed by the gap between said parts. Thus, the discharge slot (17) extends circularly over the entire perimeter of the beads (8a, 8b), it could also be adjustable through adjustment means that can vary the respective positioning of the two parts (16a, 16b) of the heel. Note that during the pressurization of the enclosure (10), the flanges of the portions (16a, 16b) of the beads form the sealing edges (13a, 13b) against which the tire (2) collapses and more precisely its unembedded zone located in the vicinity of the heel (3a, 3b).

According to the preferred embodiment of the mold (6) of the vulcanizing device, the discharge holes (11) are evenly distributed over the entire groove (12). The number of orifices and their respective dimensions may vary depending on the type of tire to be retreaded and the press used, for example. According to the illustrated embodiment, the groove (12) comprises between 25 and 40 discharge ports (11) each having a diameter greater than 1 mm as shown in Figures 3 to 5 and preferably 3 mm. The outlet openings (11) and the groove (12) have an identical configuration on the lower bead (8b), however it could be otherwise and the positioning, dimensions or shape of the groove, the discharge holes and sealing lips or ridges (11, 12, 13a, 13b) could be different on the upper bead (8a) and the lower bead (86).

According to the invention, the vulcanization device comprises complementary sealing means (MEC), these complementary sealing means comprise a peripheral seal (18) intended to prevent the leakage of air that is introduced into the enclosure of the mold (6) occupied by the tire (2). For this, the respective crowns (14a, 14b) of the beads (8a, 8b) are provided at their ends with grooves (19a, 19b) intended to receive the seal (18). According to the preferred embodiment, the upper bead (8a) is provided with a conical groove (19a) in which is enclosed the seal (18) while the lower bead (8b) has a wide and shallow parallelepiped throat to allow the deformation of the seal (18) during the introduction of the beads (8a, 8b).

According to the preferred embodiment of the vulcanizing device, the bead (8, 8a, 8b) has at least one air inlet (21) intended to be connected to a circuit of air or steam under pressure to enable the introducing air directly into the enclosure (10) without using a membrane disposed in the enclosure that is inflated to serve as a cooking chamber. Thus, the air inlet comprises connecting means for allowing its connection to an air or steam circuit.

Thus, according to the preferred embodiment of the invention, the sealing means (ME) located on the beads make it possible to obtain a seal on the outer flanks (2b, 2c) of the tire (2) on the using the evacuation groove <B> (il, </ B> 12) and its peripheral lips (13a, 13b) and obtaining a seal during pressurization of the enclosure (10) thanks to the peripheral seal (18). Therefore, during inflation air is introduced directly into the enclosure to put the tire under pressure, which allows on the one hand to obtain a uniform bias of the tire against the walls of the mold (6 ) Unlike the devices of the prior art where the stress depends on the shape that takes the cooking chamber that is inflated. On the other hand, it reduces cooking cycles by limiting the maximum heat loss due to the presence of the cooking chamber and the presence of air between the tire and the walls of the mold. This also makes it possible to obtain a better distribution of the raw rubber during the pressurization of the tire and thus to obtain a better quality of vulcanization of this rubber.

It goes without saying that one would not leave the protective field of the invention by producing a heel (8) in three parts (8a, 8b, 8c) as shown in the embodiment variant illustrated in FIG. According to this variant, the upper bead (8a) and the lower bead (8b) are separated by an intermediate ring (8c) which carries the air connections (21) radially and which has two peripheral seals (18a, 18b) to form the complementary sealing means (MEC).

Moreover, according to the two embodiments illustrated in FIGS. 12 and 13 which represent Tubeless type presses, the upper and lower heels (8a, 8b) have a different configuration and the tightness of the enclosure (10) can -be obtained using seals (18a, 18b) no longer located on a central ring but along transverse complementary parts (26a, 26b) of the press body (9). According to these variants, the beads can be made in several parts and the circular sealing edge (13) can thus be obtained at the interface between the parts forming the beads as shown in FIG. 13.

Furthermore, it is important to note that according to the preferred embodiment, the mold (6) is arranged to receive only the tire (2) and is thus provided with one or more air inlets (21). intended to allow inflation of the tire (2) in the mold (6) directly without the intermediary of a deformable cooking chamber by introducing air or steam under pressure directly into the chamber (10) . Furthermore, the invention also relates to the tire retreading method (2) associated with the vulcanization device (1). This method advantageously comprises a main step where the enclosure (10) of the mold (6) which contains the tire (2) is pressurized by directly introducing air or steam. This is possible thanks to the air evacuation means of the device which make it possible to evacuate the air present between the sidewalls and the walls of the mold as well as to the sealing lips of the mold and the complementary sealing means of the device. which make the enclosure (10) airtight and allow it to be put under direct pressure without using a flexible membrane forming a cooking chamber. This method and its associated vulcanization device advantageously make it possible to retread any type of tire, and in particular tubetype and tubeless tires, even when their lips (2d, 2e) have deteriorated.

It can also be noted, as shown in Figure 10, that the heels (8a, 8b) have guide means or centering to facilitate the introduction of heels and tire in the press. These guide means are advantageously formed by a peripheral shoulder (41) having a conical insertion portion (41a).

Of course, the invention is not limited to the embodiments described and represented by way of examples, but it also includes all the technical equivalents as well as their combinations.

Claims (10)

<U> CLAIMS </ U> 1. Vulcanizing device (1) for retreading tires (2) of the type comprising a press body (9) in which is disposed a mold (6) intended to receive the tire (2) covered with rubber (4) intended to to be vulcanized characterized in that it comprises sealing means (ME) arranged on the mold (6) for preventing the presence of air between the sidewalls (2b, 2c) of the tire (2) and the walls of the mold (6) during vulcanization. 2. vulcanization device (1) according to claim 1 characterized in that the sealing means (ME) are arranged in the mold (6) to cooperate with the end of the flanks (2b, 2c) of the tire in a zone not exhausted (20) of the tire (2). 3. vulcanization device (1) according to claim 2 characterized in that the cooperation between the sealing means (ME) and the tire (2) is at the level of the rounding (20) formed by the flanks ( 2b, 2c) with the heel (3a, 3b) of the tire. 4. vulcanization device (1) according to any one of the preceding claims characterized in that the sealing means (ME) comprise means for removing air (11, 12) and / or lips or ridges sealing (13a, 13b). 5. vulcanization device (1) according to claim 4 characterized in that the air evacuation means (11, 12) are constituted by a discharge groove (12) in which are regularly distributed outflow orifices air (11). 6. Vulcanizing device (1) according to claim 5 characterized in that the sealing lips (13a, 13b) are constituted by the edges of the groove (12). 7. vulcanization device (1) according to any one of the preceding claims characterized in that the mold (6) is constituted by the assembly of sectors (7) and a heel (8) formed in two parts, a upper part (8a) and a lower part (8b) each carrying sealing means (ME) of the mold. 8. vulcanization device (1) according to any one of the preceding claims characterized in that the mold (6) comprises complementary sealing means (MEC) for preventing the escape of air located in the enclosure ( 10) that it forms and in that it comprises at least one air inlet (21) which allows the pressurization of the enclosure (10). 9. Vulcanizing device (1) according to claims 7 and 8 characterized in that the complementary sealing means (MEC) are constituted by a peripheral seal (18) disposed between the upper bead (8a) and the lower bead (8b). ). 10. A tire retreading method using a vulcanization device (1) according to any preceding claim characterized in that it consists in a main step to pressurize the enclosure (10) formed by the mold (6). ) by introducing air or steam directly into the enclosure (10).