Patent Publication Number: US-2023150216-A1

Title: Tire mold for ventless tire molding

Description:
TECHNICAL FIELD 
     The present invention relates to tire molds having a vacuum device to draw a vacuum on the mold cavity to produce pneumatic and non-pneumatic tires having an advanced visual appearance. The present invention also relates to molding processes using such tire molds. 
     BACKGROUND OF THE INVENTION 
     It is known to have uncured tires (also called “green tires”) placed into a tire mold to provide its radially outer surface with a specific tread design and cure it. Upon closure of the tire mold, the tire is cured at elevated temperature, wherein gases or air between the tire mold and the tire can be vented through small venting passages/channels in the tire mold. As a result of processes including such venting passages in the tire mold, so-called spews remain and protrude from the tire surface. It would be advantageous to improve the look of the tire by avoiding the presence of such spews. 
     Different venting technologies relying on sophisticated small venting devices are known to avoid spews or make them smaller. However, each mold segment has to be provided with hundreds of such venting devices or channels. This is, in particular, the case for winter tires because the tread blocks and their sipes require that all tiny elements of the tread are provided with a corresponding venting passage in the mold segments. It is expensive and time-consuming to ensure venting in such a way. Venting devices may also be blocked which may result in quality problems and the need for intensive cleaning or maintenance. 
     Another known technology is to draw a vacuum on the tire mold before curing the tire with the idea that the air is removed before curing such that venting could be reduced to a minimum which could help to reduce costs significantly and improve the look of the tire. For example, EP2881230 is describing such a tire mold and process. This document describes a system for providing a vacuum in a segmented tire mold, the system comprising a vacuum container and a segmented tire mold. The vacuum container seals the tire mold to make it airtight. The tire mold has an upper sidewall assembly and a lower sidewall assembly, a plurality of radially moveable tread mold segments operable with the upper sidewall assembly and the lower sidewall assembly to define a tire mold cavity in the closed position of the tire mold, a conical actuating ring assembly surrounding the tread mold segments for providing a radial movement of the tread mold segments into engagement with the upper sidewall assembly and the lower sidewall assembly. The vacuum container comprises a top-sealing means between the actuating ring assembly and the upper sidewall assembly, and a bottom sealing means between the actuating ring assembly and the lower sidewall assembly, such that the tire mold is airtight and ready for evacuation or evacuated only when fully closed. The top sealing means and the bottom sealing means comprise silicone. The tire mold and the vacuum container have no sliding seals. 
     U.S. Pat. 4,573,894 and U.S. Pat. 4,595,553 both describe a method and apparatus in which a tire mold is closed to within approximately one inch of full closure with a green tire in place therein for molding, and the tire mold is then evacuated employing a vacuum conduit before full mold closure whereby air within the mold cavity is evacuated and the necessity for vent holes in the tire mold is eliminated. The tire mold can be free of vent holes in the tread, sidewalls, and bead portions of the tire mold and includes, along the parting line, at least one vacuum conduit whereby the mold cavity may be evacuated to not more than 16932 Pa within not more than about 60 seconds employing a source of vacuum. Seals are provided radially outward of the vacuum conduit along the parting line, and, where necessary, adjacent to any moveable bead ring associated with the tire mold. Seals are, preferably, of a type wherein a differential between pressures experienced by one seal surface and obverse seal surface causes a more effective sealing arrangement. 
     As similar idea is found in U.S. Pat. 7,056,109 which describes a tire vulcanizing device that includes an upper plate and a lower plate which can be relatively displaced toward and away from each other, and a tire mold for vulcanizing and molding a tire arranged between the upper plate and the lower plate. The tire mold includes an upper and a lower side mold members arranged on the upper plate side and the lower plate side, respectively, and a plurality of sector mold members arranged between the upper and the lower side mold members. An outer ring for positioning the sector mold members in the radial direction is arranged on the lower plate side. An actuator means for opening the sector mold member is arranged on the lower plate, capable of vertical elevation. 
     CN109176988 discloses a sealing device, which cooperates with the guide ring and the base of the evacuated tire mold to seal the evacuated tire mold. The sealing device includes a first sealing element, a floating sealing ring and an elastic device. The base has a first ring groove arranged in a circumferential direction, and the floating seal ring is arranged in the first ring groove by the elastic device. The elastic device is configured to provide an elastic force to bring the floating seal ring close to the guide ring. The first seal is provided to an end of the floating seal ring close to the guide ring, and the first seal is configured to make the guide ring and the sealing device cooperate to achieve sealing. 
     CN209504658 describes a vacuum sealing device that comprises an adjusting part, an elastic device and a first sealing piece. The base is provided with an annular groove formed in the circumferential direction, and the adjusting part is arranged in the annular groove through an elastic device. The elastic device is configured to provide elastic force for enabling the adjusting part to be close to the middle die sleeve. The first sealing piece is embedded in the end part, close to the middle die sleeve, of the adjusting part; the first sealing piece is configured to achieve sealing between the middle die sleeve and the base. The vacuum sealing device further comprises a second sealing piece. The second sealing piece is arranged between the adjusting part and the sidewall of the annular groove. 
     While the above documents describe interesting configurations, there is still a need for further development, for instance, for an improved durability of at least a part of the seals, and/or to efficiently evacuate air/gas out of the mold so as to obtain a smooth visual appearance of the tire surface. 
     SUMMARY OF THE INVENTION 
     One or more of the above needs can be met by the tire mold according to the present invention wherein vacuum is generated within the mold cavity before the tire mold is fully closed and preferably before the cutting elements (such as blades) contact the surface of the green tire, and wherein the sealing by closing seal members is not achieved by compression of the said closing seal members but by contact between closing seal members and cooperating surfaces. The molding processes and tire molds of the present disclosure are remarkable in that this contact is achieved by moving and/or deforming one or more closing seal members by suction forces generated by a venturi effect. In the tire molds and the molding processes according to the present disclosure, the vacuum device can be activated before the tire mold is sealed because the airflow generated by the activation of the vacuum device causes a movement and/or deformation of the one or more closing sealing members from a rest condition to a working condition in which they seal the tire mold. 
     The present invention is defined by the independent claims. Preferred embodiments are provided in the dependent claims and in the summary of the invention herein below. 
     According to a first aspect, the present invention is directed to a tire mold having one or more moveable elements that are displaceable to bring the tire mold into an open or into a closed position. The tire mold comprises an actuating ring, a top plate and a bottom plate, upper and lower side members, a plurality of mold segments and slide blocks, wherein the upper and lower side members and the plurality of mold segments define a mold cavity. The tire mold further comprises a vacuum device arranged and/or configured to remove the gas from the mold cavity upon its activation wherein the tire mold has sealing means comprising one or more closing seal members configured to cooperate with associated cooperating surfaces for sealing the mold cavity by contact with each other. The one or more closing seal members and the associated cooperating surfaces being moveable relative to each other during or upon displacement of the one or more moveable elements. Further, said one or more closing seal members are (placed) in a position in which they are facing their associated cooperating surfaces without contacting them, both in a partial closure position of the tire mold and in the closed position of the tire mold when the vacuum device is not activated. 
     According to a second aspect of the invention, a tire mold has one or more moveable elements that are displaceable to bring the tire mold into an open or into a closed position, the tire mold comprising an actuating ring, a top plate and a bottom plate, upper and lower side members, a plurality of mold segments and slide blocks. The upper and lower side members and the plurality of mold segments define a mold cavity and the tire mold further comprises a vacuum device arranged and/or configured to remove the gas from the mold cavity upon its activation. Moreover, the tire mold has sealing means comprising one or more closing seal members configured to cooperate with associated cooperating surfaces for sealing the mold cavity by contact with each other. The one or more closing seal members and the associated cooperating surfaces being moveable relative to each other during or upon the displacement of the one or more moveable elements. Furthermore, both in a partial closure position of the tire mold and in the closed position of the tire mold, said one or more closing seal members are arranged to face their associated cooperating surfaces without contacting them in a rest condition and are configured to change from their rest condition to a working condition in which they are in contact with their associated cooperating surfaces by suction upon activation of the vacuum device. 
     According to a third aspect, the present invention is directed to a tire mold having one or more moveable elements which are displaceable to bring the tire mold into an open or into a closed position, the tire mold comprising an actuating ring, a top plate and a bottom plate, upper and lower side members, and a plurality of mold segments and slide blocks. The upper and lower side members and the plurality of mold segments define a mold cavity and the tire mold further comprises a vacuum device arranged and/or configured to remove gas from the mold cavity upon its activation. Furthermore, the tire mold has sealing means comprising one or more closing seal members configured to cooperate with associated cooperating surfaces for sealing the mold cavity by contact with each other, the one or more closing seal members and the associated cooperating surfaces being moveable relative to each other during the displacement of the one or more moveable elements. Both, (i) in a partial closure position of the tire mold in which the one or more moveable elements still have a stroke of at least 3.0 mm before the tire mold is closed, and (ii) in the closed position of the tire mold, said one or more closing seal members are arranged to face their associated cooperating surfaces without contacting them in a rest condition in which they are spaced with a distance of at most 1.5 mm from the associated cooperating surfaces and are configured to change from their rest condition to a working condition in which they are in contact with their associated cooperating surfaces upon activation of the vacuum device. 
     Further optional features to define the tire mold according to the first aspect, the second aspect and/or the third aspect are provided herein below. 
     In one embodiment, the tire mold is a vent-less tire mold, or has, in other words, mold segments which are free of venting passages and/or venting devices. 
     It is understood that the one or more closing seal members can change from a rest condition in which they are not in contact with an associated cooperating surface to a working condition in which each of them is in contact with and/or pressed against an associated cooperating surface. The activation of the vacuum device to draw a vacuum in the mold cavity can be started before the tire mold is sealed, thereby causing an airflow passing between the one or more closing seal members and their associated cooperating surfaces. Suction forces are generated by the venturi effect which move and/or deform the one or more closing seal members to allow them to change from their rest condition to their working condition causing the mold cavity (i.e. the tire mold cavity) to be sealed in an airtight manner. 
     The suction by venturi effect is possible because the one or more closing seal members are placed next to a cooperating surface when the mold is still open (e.g. in a partial closure position of the tire mold). In other words, the one or more closing seal members are close enough to the one or more associated cooperating surfaces to generate a constriction causing an increase of the air-flow speed beside the one or more closing seal members upon activation of the vacuum device. The one or more closing seal members are configured and/or adapted to change from their rest condition to their working condition by deformation, displacement or both deformation and displacement. Each of the one or more closing seal members can be held by a carrier element, the displacement of the one or more closing seal members by suction is typically not caused by a displacement of their carrier element, but by a displacement of the one or more closing seal members relative to their respective carrier element. 
     For example, the one or more closing seal members are configured and/or adapted to change from a rest condition in which they are not in contact with their associated cooperating surfaces to a working condition in which they are in contact with their associated cooperating surfaces, such as by suction generated by activation of the vacuum device causing the mold cavity to be sealed in an airtight manner. 
     For example, the one or more closing seal members seal the tire mold by deformation, displacement or both deformation and displacement. Displacement is understood to be a displacement of the closing seal member relative to the member of the tire mold that supports it. 
     With respect to the tire mold according to the present invention, it is remarkable that the one or more closing seal members do not need to function in compression but can perform their sealing function by deformation and/or displacement so as to come into sealing contact with their associated cooperating surfaces. Once the vacuum device is deactivated, there is no more suction and the one or more closing seal members return into their rest condition. As a consequence, the one or more closing seal members are not in a deformed, displaced or compressed state anymore, but in a rest condition during curing of the tire. This helps to increase the life of the one or more closing seal members compared to closing seal members that are still deformed or compressed during the tire cure, when the temperature of the seal members is the highest. 
     In a preferred embodiment, at least one closing seal member is made of an elastic material and/or elastomer based material. For instance, the elastic material comprises an elastomer selected from resin cured butyl rubbers, silicone rubbers, phenolic cured butyl rubbers, fluorocarbon rubbers and any mixture thereof. For example, the use of an elastic material allows the closing seal member to return to its rest condition as soon as the suction forces are stopped. 
     For example, in the partial closure position of the tire mold (i.e. a position in which the one or more closing seal members are facing their associated cooperating surfaces without contacting them) and in the closed position of the tire mold, when the one or more closing seal members are in their rest condition, they are spaced from their associated cooperating surfaces with a distance of at most 2.0 mm, preferably at most 1.8 mm, more preferably at most 1.5 mm, even more preferably at most 1.2 mm, and most preferably at most 1.0 mm or at most 0.8 mm. 
     For example, in the partial closure position or in the closed position of the tire mold, when the one or more closing seal members are in their rest condition, they are spaced from their associated cooperating surfaces with a distance ranging from 0.1 mm to 2.0 mm, preferably from 0.1 mm to 1.8 mm, more preferably from 0.2 mm to 1.5 mm, even more preferably from 0.3 mm to 1.2 mm, and most preferably from 0.4 mm to 1.0 mm or from 0.5 mm to 0.8 mm. 
     For example, the one or more moveable elements are displaceable from an initial position to a final position so as to allow bringing the tire mold into a closed position. The partial closure position of the tire mold is a position in which the one or more moveable elements are in an intermediate position and still have a stroke left to reach their final position to close the tire mold. 
     According to a preferred embodiment of the disclosure, the vacuum device is activated (or active) during closing of the tire mold, when the tire mold is in its partial closure position. 
     For example, in the partial closure position of the tire mold, the one or more moveable elements still have a stroke of at least 3.0 mm (before the tire mold is closed), preferably at least 5.0 mm, more preferably at least 6.0 mm, even more preferably at least 8.0 mm, and most preferably at least 10.0 mm. 
     For example, in the partial closure position of the tire mold, the one or more moveable elements still have a stroke ranging from 3.0 mm to 25.0 mm before the tire mold is closed (or in the closure position), preferably from 5.0 mm to 20.0 mm, more preferably from 6.0 mm to 18.0 mm, and even more preferably from 8.0 mm to 15.0 mm. 
     For example, the mold segments have an inner molding surface with one or more cutting elements (e.g. blades) with a given height. At the partial closure position of the tire mold, the one or more moveable elements still have a stroke greater than the (maximum) height of the one or more cutting elements before the tire mold is closed. 
     For example, the mold segments have an inner molding surface with one or more cutting elements (such as blades), wherein in the partial closure position of the tire mold, the cutting elements are not in contact with the green tire and the one or more closing seal members are placed at a distance of at most 2.0 mm from their associated cooperating surfaces so as to be moveable and/or deformable by suction upon activation of the vacuum device. Preferably said distance is at most 1.8 mm, more preferably at most 1.5 mm, even more preferably at most 1.2 mm, and most preferably at most 1.0 mm or at most 0.8 mm. 
     For example, the mold segments have an inner molding surface with one or more cutting elements (such as blades) and at the partial closure position of the tire mold the cutting elements are not in contact with the green tire. Furthermore, the one or more closing seal members are placed at a distance of at most 2.0 mm, preferably at most 1.5 mm, from their associated cooperating surfaces so as to be moveable and/or deformable by suction upon activation of the vacuum device. Moreover, the tire mold is configured such that in its partial closure position the one or more moveable elements still have a stroke of at least 3.0 mm before the tire mold is closed. Preferably said stroke is at least 5.0 mm, more preferably at least 6.0 mm, even more preferably at least 8.0 mm, and most preferably at least 10.0 mm. 
     For example, the mold segments have an inner molding surface with one or more cutting elements of a given height and at the partial closure position of the tire mold, the one or more cutting elements are still spaced from the surface of the green tire. “Green tire” means a tire in an uncured state, i.e. before a step of vulcanization. 
     In an embodiment, the actuating ring is one of the one or more moveable elements which are displaceable to bring the tire mold into an open or into a closed position. For example, the actuating ring is one of the one or more moveable elements and is displaceable from an initial position to a final position so as to close the tire mold. The mold is configured to draw a vacuum on the mold cavity before the actuating ring reaches its final position. 
     In an embodiment, one or more closing seal members comprise an upper closing seal member, a lower seal member or both of them. 
     For example, one or more closing seal members are O-ring seal members. 
     For example, the one or more closing seal members comprise an upper closing seal member being an O-ring seal member that is placed on the top plate and a lower seal member which is a T-seal member that is anchored to the bottom plate or to the actuating ring. For example, one or more closing seal members are T-seal members. 
     A T-seal member is preferably a seal having essentially a T-shaped cross section. Preferably, the T-seal has at least three (or three) legs wherein two of these legs are held by and/or are anchored to a carrier element, e.g. within a (complementary shaped) groove and/or aperture in the carrier element. The third leg extends from the carrier element and/or can be inclined laterally to the direction of its extension such as by suction forces generated by a vacuum, e.g. with a vacuum device. For instance, this may be caused by the venturi effect. 
     For example, the one or more closing seal members comprise an upper closing seal member being a T-seal member that is anchored to the top plate and a lower seal member which is a T-seal member and is anchored to the actuating ring. 
     For example, one or more carrier elements are one or more selected from the top plate, the bottom plate and the actuating ring. The one or more carrier elements hold the one or more closing seal members. 
     For example, the one or more closing seal members comprise an upper closing seal member being an O-ring seal member that is placed on the top plate and a lower seal member being a T-seal member that is anchored to the bottom plate or to the actuating ring. Preferably, an O-ring seal member has a circular or elliptical cross-section. 
     For example, the one or more closing seal members comprise an upper closing seal member being a T-seal member that is anchored to the top plate and a lower seal member that is a T-seal member and is placed on the actuating ring. 
     For example, the one or more closing seal members comprise an upper closing seal member that is placed on the top plate and the associated cooperating surface is a vertical edge of the actuating ring or a vertical edge of an upper seal plate fixed to the actuating ring. 
     With preference, the vertical edge of the actuating ring or the vertical edge of an upper seal plate has a flanged end extending vertically down and defining the cooperating surface. For example, the height of the flanged end is ranging from 5 to 25 mm, preferably from 7 to 20 mm or from 10 to 15 mm. 
     In an embodiment, the upper closing seal member is an O-ring seal member and is arranged in a groove of a vertical wall of the top plate or in a recess of a vertical wall of the top plate and maintained in position by a hook. 
     In another embodiment, the upper closing seal member is a T-seal member that is anchored in a groove of an upper surface of the top plate and extends vertically so that the cooperating surface faces a vertical side of the T-seal member. 
     In an embodiment, the one or more closing seal members comprise a lower seal member that is placed on the actuating ring, wherein the lower closing seal member is an O-ring seal member and is arranged in a groove of a vertical wall of the actuating ring. 
     For example, the one or more closing seal members comprise a lower seal member placed on the actuating ring, wherein the lower closing seal member is an O-ring seal member and is arranged in a groove of a vertical wall of the actuating ring and the cooperating surface is a vertically extending ledge arranged at the outer end of the bottom plate. 
     In another embodiment, the one or more closing seal members comprise a lower seal member which is a T-seal member and is anchored to the bottom plate or to the actuating ring and extends vertically so that the cooperating surface faces a vertical side of the T-seal member. The cooperating surface is on the actuating ring or the bottom plate respectively. 
     The terms “comprising”, “comprises” and “comprised of” as used herein are synonymous with “including”, “includes” or “containing”, “contains”, and are inclusive or openended and do not exclude additional, non-recited members, elements or method steps. The terms “comprising”, “comprises” and “comprised of” also include the term “consisting of”. 
     The reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. The particular features, structures, characteristics or embodiments may be combined in any suitable manner, as would be apparent to a person skilled in the art from this disclosure, in one or more embodiments. Furthermore, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the disclosure and form different embodiments, as would be understood by those in the art. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described by way of example and with reference to the accompanying drawings in which: 
         FIG.  1    is a partial cross-sectional view of a tire mold according to an embodiment of the present invention. 
         FIG.  2    is a schematic view of an upper closing seal member being an O-ring not yet facing its cooperating surface. 
         FIG.  3    is a schematic view of an upper closing seal member being an O-ring sealing the tire mold while it is still partially open. 
         FIG.  4    is a schematic view of an upper closing seal member being an O-ring sealing the tire mold while it is closed and the vacuum device is still activated so that the seal member is contacting the cooperating surface. 
         FIG.  5    is a schematic view of an upper closing seal member being an O-ring sealing the tire mold while it is closed and the vacuum device is not activated anymore so that the seal member returns to its rest condition, i.e. is spaced from the cooperating surface. 
         FIG.  6    is a schematic view of an upper closing seal member being a T-seal member not yet facing its cooperating surface. 
         FIG.  7    is a schematic view of an upper closing seal member being a T- seal member sealing the tire mold while it is still partially open. 
         FIG.  8    is a schematic view of an upper closing seal member being a T- seal member sealing the tire mold while it is closed wherein the vacuum device is still activated so that the seal member contacts the cooperating surface. 
         FIG.  9    is a schematic view of an upper closing seal member being a T- seal member sealing the tire mold while it is closed and the vacuum device is not activated anymore so that the seal member returns to its rest condition, i.e. is spaced from the cooperating surface. 
         FIG.  10    is another partial cross-sectional view of a tire mold according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     In embodiments of the tire mold in accordance with the present invention, one or more closing seal members do not work in compression but can perform their sealing function by deformation and/or displacement towards their associated cooperating surfaces until they (sealingly) contact their associated cooperating surfaces. Upon deactivation of the vacuum device, suction stops and the one or more closing seal members return to their rest condition. As a consequence, the one or more closing seal members are not in a working condition but a rest condition during the tire cure. This was found to increase the durability of the one or more closing seal members compared to closing seal members that are in a deformed, displaced or compressed state during the cure of the tire, i.e. when the temperature is the highest. 
     In an aspect of the present invention, a molding process is disclosed, in which a green tire having a tread, a sidewall and bead portions is formed and then molded within a tire mold. The tire mold has one or more moveable elements displaceable to bring the tire mold into an open or into a closed position. The tire mold comprises an actuating ring, a top plate, a bottom plate, upper and lower side members, a plurality of mold segments, slide blocks, and a vacuum device. The upper and lower side members and the plurality of mold segments define a mold cavity and the tire mold further comprises sealing means for sealing the mold cavity, including one or more closing seal members. Such a process can comprise one or more of the following steps:
     providing a tire mold having one or more closing seal members;   placing the green tire into the mold cavity;   placing the one or more closing seal members next to a cooperating surface so as to face it without contacting it by bringing the tire mold to a partial closure position;   drawing a vacuum on the mold cavity causing the one or more closing seal members to be moved or deformed by suction until they are in contact with the cooperating surface so that the mold cavity is sealed in an airtight manner.   

     The vacuum device is activated to draw a vacuum on the mold cavity when the tire mold has reached its partial closure position, i.e. before the tire mold is fully closed. 
     In an embodiment, such a process further comprises the steps of closing the tire mold while the vacuum device is activated and a step of curing the tire, wherein the vacuum device is deactivated during the step of curing, thereby causing the one or more closing seal members to return from their working condition back to their rest condition. 
     For example, the mold segments have an inner molding surface with one or more cutting elements, the one or more cutting elements being spaced from the green tire when the tire mold is in its open position and are contacting the green tire to cut its tread portion when the tire mold is in its closed position. Furthermore, at the partial closure position of the tire mold, the one or more cutting elements are still spaced from the green tire so that drawing the vacuum on the mold cavity is started before the one or more cutting elements come into contact with the green tire. 
     For example, the actuating ring is movable from an open position to a closed position and drawing the vacuum on the mold cavity is started before the actuating ring reaches its closed position. 
     For example, the vacuum device is activated to draw a vacuum on the tire mold for a time ranging from 3 to 60 seconds, preferably ranging from 5 to 40 seconds, more preferably ranging from 7 to 30 seconds, and even more preferably from 9 to 20 seconds. 
     Such a molding process can be carried out by tire molds in accordance with embodiments of the present invention. 
     In one embodiment, the tire mold has one or more moveable elements that are displaceable to bring the tire mold into an open or into a closed position, the tire mold comprising an actuating ring, a top plate and a bottom plate, upper and lower side members, and a plurality of mold segments and slide blocks. The upper and lower side members and the plurality of mold segments define a mold cavity. Furthermore, the tire mold comprises a vacuum device arranged to remove gas from the mold cavity upon its activation, wherein the tire mold has also sealing means comprising one or more closing seal members configured to cooperate with associated cooperating surfaces for sealing the mold cavity by contact with each other. The one or more closing seal members and the associated cooperating surfaces are moveable relative to each other during or upon displacement of the one or more moveable elements. Furthermore, said one or more closing seal members are placed in a position in which they face their associated cooperating surfaces without contacting them, both, in a partial closure position of the tire mold and in the closed position of the tire mold, when or provided that the vacuum device is not activated. 
     For example, both in (i) a partial closure position of the tire mold and (ii) the closed position of the tire mold said one or more closing seal members are arranged to face their associated cooperating surfaces without contacting them in a rest condition and are configured to change from their rest condition to a working condition in which they are in contact with their associated cooperating surfaces by suction of the vacuum device. 
     For example, both in (i) a partial closure position of the tire mold wherein the one or more moveable elements still have a stroke of at least 3.0 mm before the tire mold is closed, and in (ii) the closed position of the tire mold, said one or more closing seal members are arranged to face their associated cooperating surfaces without contacting them in a rest condition, wherein they are spaced with a distance of at most 1.5 mm from their associated cooperating surfaces and are configured to change from their rest condition to a working condition in which they are in contact with their associated cooperating surfaces upon activation of the vacuum device. 
     The one or more closing seal members can be adapted to change from a rest condition, in which they are not in contact with a cooperating surface, to a working condition, in which they are contacting their associated cooperating surfaces, upon application of suction forces generated by a venturi effect due to the activation of the vacuum device. In the working condition of the one or more closing seal members, the mold cavity is sealed in an airtight manner. Thus, it is possible to have the tire mold sealed before it is in its closed position so as to evacuate the gas from the mold cavity. Once the tire mold is closed, there is no more need for the tire mold to be sealed in an airtight manner so that the one or more closing seal members can return to their rest condition for curing the tire. Thus, in an embodiment, the tire mold is adapted to be airtight, e.g. some millimeters before the final position of the moveable element of the tire mold to remove the air. This helps to provide a mold without a venting system in the tread segments. Using such a mold results in an advanced tread pattern appearance (i.e. the tread is essentially free of spews and/or venting marks). Furthermore, since the one or more closing seal members are under stress for a relatively short time only, i.e. only when the vacuum device is activated, the durability of the one or more closing seal members is considerably improved. 
     Reference is made to  FIG.  1    which illustrates one embodiment of a tire mold  1 . The tire mold  1  comprises a plurality of mold segments which are arranged to form an annular ring when assembled. The outer tread surface of a tire is formed by the inner molding surface 3 of the mold segments which corresponds to the external surface tread molding element. The inner molding surface has a plurality of cutting elements such as sipes and/or blades (not shown) to mold the tread pattern in a green tire  5 . The mold segments may be radially moveable to allow assembly and disassembly of the tire mold about a green tire  5 . 
     The tire mold  1  further comprises a first and second sidewall plate  7 ,  9  for molding the sidewalls of the tire. Each sidewall plate  7 ,  9  joins the mold segments to form a smooth continuous surface from the tire tread to the sidewall. Each sidewall plate  7 ,  9  may comprise an optional radially outer lip  11  forming an L-shaped recess for receiving a first and second flanged end of the mold segment therein. Each sidewall plate  7 ,  9  further comprises an optional radially inner extension or lip  13  forming a second L-shaped recess for receiving a mold bead ring  15 ,  17  therein. Each bead ring  15 ,  17  has a rounded segment or curved portion for receiving a bead area of a green tire thereon. The upper and lower sidewall plates  7 ,  9 , together with the plurality of tread segments and the top and bottom bead rings  15 ,  17  cooperate to define a mold cavity for molding a green tire  5 . 
     The mold segment can comprise a tread molding element  19  and a support element  21  or comprises a tread molding element integral with the support element or comprises a tread molding element integral with the support element and with a slide block. 
     The mold segment can be formed from one or two elements. In the embodiment of  FIG.  1   , the mold segments are formed from two elements being a tread molding element  19  and a support element  21 . However, in another embodiment, the tread molding element and the support element are integrally formed to form a single element which is the mold segment. 
     Independent of how the mold segment is formed (e.g. from one or two elements), the tire mold  1  is preferably segmented and/or further comprises a container housing. 
     A container housing typically includes top and bottom plates  23 ,  25 . The bottom plate  23  has an inner annulus for supporting the sidewall plate  9  and the bead ring  17 . A plurality of slide blocks  27  are surrounding the segments. Slide blocks  27  have flanged ends for receiving and supporting the segments therein. The slide blocks  27  have a top and a bottom surface for contacting the top and bottom plates  23 ,  25  and optional wear plates (not shown). Slide blocks  27  are slidable in a radial direction. The container housing further comprises an annular actuating ring  31 . The inner radial surface  33  of the actuating ring  31  is angled for engagement with an outer angled surface  35  of slide blocks  27 . In the embodiment shown in  FIG.  1   , the actuating ring  31  is one of the one or more moveable elements that can be displaced to bring the tire mold into an open or into a closed position. However, a person skilled in the art may adapt the disclosure to a tire mold configuration in which the actuating ring is not movable. Such a configuration is known to the person skilled in the art and described in U.S. Pat. 7,056,109. 
     When the actuating ring  31  is one of the one or more moveable elements, and as the actuating ring  31  is lowered from an open position to a closed position, the inner radial surface  33  of the actuating ring  31  engages the outer angled surface  35  of slide blocks  27 , causing the slide blocks to slide radially inward. The camming action of the actuating ring  31  moves the slide blocks  27  radially inward. As slide blocks  27  move radially inward, the radially inner surface of the slide blocks  27  engages the outer surface of the adjacent mold segment, moving the mold segment radially inward as the actuating ring  31  is lowered into its closed position that defines the diameter-reducing limit position, causing the blades and/or the sipes to cut the surface of the green tire  5 . 
     The tire mold  1  further comprises an upper seal plate  37 . The upper seal plate  37  is fixedly secured via an upper seal member  39  to the actuating ring  31  so that it moves with the actuating ring  31 . 
     A bottom seal member  41  is placed between the contact surface of the bottom plate  23  and the second sidewall plate  9 . Similarly, a top seal member  43  is placed between the contact surface of the top plate  25  and the first sidewall plate  7 . 
     The tire mold  1  further comprises at least one closing seal member  45 ,  47  arranged and adapted to seal the mold cavity before the tire mold  1  is closed, for example, before the actuating ring  31  reaches its closed position. The one or more closing seal members  45 ,  47  can be selected from one or more upper closing seal members  47 , one or more lower seal members  45  or both of them. The one or more closing seal members  45 ,  47  differ from the other seal members, such as upper seal member  39 , the bottom seal member  41  and the top seal member  43 , in that they are associated with a cooperating surface, wherein one is moveable relative to the other during the displacement of the tire mold  1  from its open position to its closed position (i.e. during the displacement of the moveable elements of the tire mold  1 ), and in that the one or more closing seal members  45 ,  47  can change from a position in which they are not in contact with their associated cooperating surfaces (i.e. in their rest condition) to a position in which they contact their associated cooperating surfaces (i.e. in their working condition) by suction generated by the vacuum device, thereby causing the mold cavity to be sealed in an airtight manner. 
     For example, the one or more closing seal members  45 ,  47  are configured to change from their rest condition to their working condition by deformation, displacement or both deformation and displacement. 
     For example, at least one of the one or more closing seal members  45 ,  47  is of an O-ring type, as illustrated in  FIGS.  1  to  4  and  10   . The deformation and/or displacement of the one or more closing seal members  45 ,  47  of the O-ring type comprises increasing its diameter until coming into contact with its associated cooperating surface. 
     For example, at least one of the one or more closing seal members  45 ,  47  is of a T-type, as illustrated in  FIGS.  6  to  10   . The deformation and/or displacement of the one or more closing seal members  45 ,  47  of the T-type comprises inclining the seal member (e.g. one of its legs) until coming into contact with its associated cooperating surface. 
     In a preferred embodiment, the one or more closing seal members are made of an elastic material. With preference, the elastic material comprises an elastomer selected from resin cured butyl rubbers, silicone rubbers, phenolic cured butyl rubbers, fluorocarbon rubbers and any mixture thereof. 
     In the embodiment depicted in  FIG.  1   , both the upper and the lower closing seal members  45 ,  47  are O-ring seal members. However, the disclosure encompasses also embodiments in which both the upper and the lower closing seal members are T-seal members. In other embodiments, the upper closing seal member is an O-ring seal member, the lower seal member is a T-seal member (as in  FIG.  10   ) or the upper closing seal member is a T-seal member and the lower seal member is an O-ring seal member. The disclosure also encompasses embodiments, in which only one selected from the upper closing seal member and the lower closing seal member can change from a position in which it is not in contact with its cooperating surface to a position in which it is contacting its cooperating surface by suction generated by the vacuum device. 
     Irrespective of a specific embodiment, in the position in which the one or more closing seal members  45 ,  47  face their associated cooperating surfaces without contacting them (such as in the partial closure position of the tire mold or in the closed position of the tire mold, when the vacuum device is not activated), they are preferably spaced with a distance D of at most 2.0 mm, preferably of at most 1.8 mm, more preferably of at most 1.5 mm, even more preferably of at most 1.2 mm, and most preferably of at most 1.0 mm or 0.8 mm. The distance D is illustrated on  FIGS.  2 ,  5 ,  6  and  9   . 
     For example, in the position in which the one or more closing seal members  45 ,  47  face their associated cooperating surfaces without contacting them (such as in the partial closure position of the tire mold or in the closed position of the tire mold, when the vacuum device is not activated), they are spaced with a distance D ranging from 0.1 mm to 2.0 mm, preferably from 0.1 mm to 1.8 mm, more preferably from 0.2 mm to 1.5 mm, even more preferably from 0.3 mm to 1.2 mm, and most preferably from 0.4 mm to 1.0 mm or from 0.5 mm to 0.8 mm. As mentioned above, the distance D is illustrated on  FIGS.  2 ,  5 ,  6  and  9   . 
     The one or more moveable elements can be displaced from an initial position to a final position to bring the tire mold into an open or into a closed position. The partial closure position of the tire mold is the first position during the stroke of the moving element(s) wherein the one or more moveable elements are in an intermediate position so that they have a stroke left before reaching their final position to close the tire mold but wherein the one or more closing seal members are close enough to their associated cooperating surfaces so that they are movable by suction (via the venturi effect) to seal the tire mold upon activation of the vacuum device. 
     For example, in the position where the one or more closing seal members  45 ,  47  face their associated cooperating surfaces without contacting them while the tire mold  1  is still partially open (i.e. in the partial closure position of the tire mold), the one or more moveable elements still have a stroke of at least 3.0 mm before the tire mold  1  is closed. Preferably said stroke is at least 5.0 mm, more preferably at least 6.0 mm, even more preferably at least 8.0 mm, and most preferably at least 10.0 mm. 
     For example, in the position where the one or more closing seal members  45 ,  47  are facing their associated cooperating surfaces without contacting them, and while the tire mold  1  is still partially open (i.e. in the partial closure position of the tire mold), the one or more moveable elements still have a stroke ranging from 3.0 mm to 25.0 mm before the tire mold is closed. Preferably said stroke is ranging from 5.0 mm to 20.0 mm, more preferably from 6.0 mm to 18.0 mm, and even more preferably from 8.0 mm to 15.0 mm. 
     For example, the mold segments have an inner molding surface with one or more cutting elements of a given height and, in the position in which the one or more closing seal members face their associated cooperating surfaces without contacting them while the tire mold is still partially open (i.e. in the partial closure position of the tire mold), the one or more moveable elements still have a stroke greater than the height of the one or more cutting elements (such as the blades) before the tire mold is closed. 
     For example, the mold segments have an inner molding surface with one or more cutting elements (such as blades) and the one or more closing seal members are placed during the closing of the tire mold at a distance of at most 2.0 mm from their associated cooperating surfaces so as to be moveable and/or deformable by suction forces generated by the activation of the vacuum device, in a position in which the cutting elements are not yet in contact with the green tire. Preferably said distance is at most 1.8 mm, more preferably at most 1.5 mm, even more preferably at most 1.2 mm, and most preferably at most 1.0 mm, and even most preferably of at most 0.8 mm. For example, they are spaced with a distance ranging from 0.1 mm to 2.0 mm, preferably from 0.1 mm to 1.8 mm, more preferably from 0.2 mm to 1.5 mm, even more preferably from 0.3 mm to 1.2 mm, and most preferably from 0.4 mm to 1.0 mm or 0.5 mm to 0.8 mm. 
     For example, the mold segments have an inner molding surface with one or more cutting elements. Furthermore, the one or more closing seal members are placed during the closing of the tire mold at a distance of at most 2.0 mm, preferably at most 1.5 mm, from their associated cooperating surfaces so as to be moveable and/or deformable by suction upon the activation of the vacuum device in a position in which the one or more moveable elements have still a stroke of at least 3.0 mm before the tire mold is closed. Preferably, said stroke is at least 5.0 mm, more preferably at least 6.0 mm, even more preferably at least 8.0 mm, and most preferably at least 10.0 mm. 
     In the embodiment illustrated in  FIGS.  1  to  5   , the upper closing seal member  47  is placed on the top plate  25  and the associated cooperating surface is a vertical edge of an upper seal plate  37  fixed to the actuating ring  31 . In an embodiment not shown, the associated cooperating surface is a vertical edge of the actuating ring. This is for example the case when the upper seal plate is integrally formed with the actuating ring. 
     As depicted, the vertical edge of the actuating ring or the vertical edge of an upper seal plate  37  has a flanged end  51  extending vertically down and defining the cooperating surface. For example, the height of the flanged end  51  is ranging from 5 mm to 25 mm, preferably from 7 mm to 20 mm or from 10 mm to 15 mm. 
     When the tire mold is open as illustrated in  FIG.  2   , the upper closing seal member  47  is not facing yet its associated cooperating surface  51 . In a partial closing position of the tire mold, as illustrated in  FIG.  3   , as soon as the upper closing seal member  47  is facing its associated cooperating surface  51 , the vacuum device can be activated causing the upper closing seal member  47  to be placed in its working position so that the tire mold is sealed. 
       FIG.  4    illustrates the closed and sealed tire mold wherein the vacuum device is still activated, keeping the upper closing seal member  47  in its working position.  FIG.  5    illustrates the tire mold being closed but not anymore sealed since the vacuum device is not active anymore so that the upper closing seal member  47  is in its rest position. 
     The top plate  25  may contain a recess  53  to receive the flanged end  51  when the tire mold is closed as illustrated in  FIGS.  4  and  5   . 
     The upper closing seal member  47  may be arranged in a groove  63  of a vertical wall of the top plate  25  (see  FIGS.  4  and  5   ) or in a recess of a vertical wall of the top plate  25  and maintained in position by a hook  49 . The hook can be fixed to the top plate as illustrated in  FIGS.  2  and  3   , or can be integral with the top plate  25  as illustrated in  FIGS.  4  and  5    in the form of a wall of the groove  63 . 
     As it is understood from  FIGS.  2  to  5   , the upper closing seal member  47  can contact its cooperating surface which is the flanged end  51  of the upper seal plate  37  so as to exert its sealing function before the closure of the tire mold, i.e. when a stroke H is present between the upper seal plate  37  and an upper surface  55  of the top plate  25 , as shown in  FIG.  3   . For example, the remaining stroke H before the closure of the tire mold is at least 3.0 mm. 
     The outer surface of the flanged end  51  of the upper seal plate  37  is the associated cooperating surface of the upper closing seal member  47  and the flanged end  51  of the upper seal plate  37  is one of the moveable elements that is displaced to bring the tire mold into an open or closed position. In  FIGS.  3  and  4   , the vacuum device is activated so that the upper closing seal member  47  is in contact with its associated cooperating surface. In  FIG.  5   , the vacuum device is not activated and the upper closing seal member  47  is in its rest condition, i.e. away or spaced from its associated cooperating surface. 
     Generally, it is remarked that even if the vacuum device is provided in a remote position it can be still considered as a part of the tire mold within the meaning of the present disclosure. 
     Back to  FIG.  1   , it is understood that similarly, the tire mold  1  may comprise a lower closing seal member  45  arranged between the bottom plate  23  and the actuating ring  31 . For example, the lower closing seal member  45  may be arranged in a groove of a vertical wall of the actuating ring  31  or in a recess of a vertical wall of the actuating ring  31  and maintained in position by a hook. The cooperating surface of the lower closing seal member  45  is the inner surface of a vertically extending ledge  29  arranged at the outer end of the bottom plate  23 . The vertically extending ledge  29  preferably extends in a vertically upward direction. For example, the height of the vertically extending ledge  29  is ranging from 5 to 25 mm, preferably from 7 to 20 mm, or from 10 to 15 mm. Here the lower seal member is placed on one of the moveable elements (i.e. the actuating ring  31 ) that is displaceable to bring the tire mold  1  into an open or a closed position, whereas its associated cooperating surface is in a fixed position. 
     According to embodiments of the present invention, the one or more closing seal members are arranged at positions in which they exhibit the intended sealing function before the full closure of the tire mold, thereby allowing suction and removal of trapped air/gases to be started as soon as these seal members exhibit their sealing function (before the diameter-reducing limit position is reached). As a consequence, gas within the mold cavity can be exhausted by vacuum suction so as to efficiently remove the gas without forming vent holes, especially in the tread molding segments. The removal of the gas preferably starts before the blades come into contact with the surface (e.g. the tread surface) of the green tire. In a preferred embodiment, the tire mold is a vent-less tire mold. 
     The embodiments illustrated in  FIGS.  6  to  10    show at least one closing seal member  45 ,  47  which is a T-seal member. 
     As illustrated in the embodiment of  FIGS.  6  to  9   , the closing seal member  47  can be a T-seal member that is extending vertically from an upper surface  55  of the top plate  25  (in which it is anchored).  FIG.  6    illustrates the tire mold in the open position wherein the cooperating surface  59  (here the vertical edge  59  of the upper seal plate  37 ) is not facing the upper closing seal member  47  yet. The stroke H wherein the closing seal member can exert its sealing function before the closure of the tire mold corresponds to the height of the T-seal member as from the upper surface of the top element. For example, the upper closing seal member  47  (which is a T-seal member) extends vertically up from the upper surface  55  of the top plate  25  to a height shown by its outer vertical wall  57  of at least 3.0 mm, preferably at least 5.0 mm, more preferably at least 6.0 mm, even more preferably at least 8.0 mm, and most preferably at least 10.0 mm. For example, the height of the T-seal member as determined from the upper surface  55  of the top plate  25  ranges from 5.0 mm to 25.0 mm, preferably from 7.0 mm to 20.0 mm, or from 10.0 mm to 15.0 mm. In such a configuration, it is understood that the upper seal plate  37  is one of the moveable elements that is displaceable to bring the tire mold into an open or a closed position. 
     The present disclosure also encompasses embodiments (not illustrated) in which T-seal members have a height (as determined from the upper surface  55  of the top plate  25 ) ranging from 3.0 mm to 25.0 mm and which cooperate with a cooperating surface being a flanged end of the upper seal plate or of the actuating ring. The disclosure also encompasses embodiments (not illustrated) wherein T-seal members are anchored in the upper seal plate or the actuating ring and extend vertically down and which are cooperating with a cooperating surface in the form of a vertical wall of the upper plate. With preference, the T-seal members have a height ranging from 3.0 mm to 25.0 mm. In this embodiment, and since the upper seal member is anchored in the upper seal plate, the latter is one of the moveable elements that is displaceable to bring the tire mold into an open or a closed position. 
     In a partial closing position of the tire mold, as illustrated in  FIG.  7   , and as soon as the upper closing seal member  47  faces its associated cooperating surface  59 , the vacuum device can be activated, causing the upper closing seal member  47  to be placed in its working position so as to seal the tire mold. 
     In one embodiment of this invention after the mold is sealed a green tire is pushed against the inner molding surfaces of the mold having one or more cutting elements with a cure bladder. More specifically, the green tire is pressed outwardly against the mold surface by means of an inner fluid expandable cure bladder. By this method the green tire is shaped against the outer mold surface which defines the tread pattern and configuration of sidewalls of the tire. By application of heat the tire is cured. Generally, the bladder is expanded by internal pressure provided by a fluid such as hot gas, hot water and/or steam which also participates in the transfer of heat for curing or vulcanization purposes. The tire can then be allowed to cool to some degree in the mold, sometimes aided by adding cold or cooler water to the cure bladder. Then the mold is opened, the bladder collapsed by removal of its internal fluid pressure and the tire removed from the tire mold. 
     Cure bladders which are useful in conjunction with the tire molds of this invention are typically comprised of butyl rubber. Butyl rubber is a copolymer of predominantly isobutylene with small amounts of diene monomers, usually isoprene to give sufficient unsaturation to allow the butyl rubber to be crosslinked. Brominated copolymers of isobutylene and para-methylstyrene which can conventinet be used in manufactureing cure bladders is commercially available from Exxon Mobil. 
       FIG.  8    illustrates the closure of the tire mold, wherein the vacuum device is still activated or, in other words, active.  FIG.  9    shows the tire mold in its closed position, wherein the vacuum device is not activated anymore. It can be seen from  FIGS.  7  and  8    that the upper closing seal member  47  is deformed by inclination so that the surface of its radially outer wall is pressed against the vertical edge  59  of the upper seal plate  37 . Upon deactivation of the vacuum device (not shown), the upper closing seal member  47  will return to its rest condition and will therefore be spaced from its associated cooperating surface (here the vertical edge  59  of the upper seal plate  37 ) with a distance ranging from 0.1 mm to 2.0 mm, preferably from 0.1 mm to 1.8 mm, more preferably from 0.2 mm to 1.5 mm, and even more preferably from 0.3 mm to 1.2 mm, and most preferably from 0.4 mm to 1.0 mm or from 0.5 mm to 0.8 mm. Thus, the upper closing seal member  47  exerts a sealing function under the action of suction forces of the vacuum device only, thereby preventing contact between the upper closing seal member  47  and upper seal plate  37  before and after the vacuum device is active and therefore limiting wear of the upper closing seal member  47 . 
     In the embodiment of  FIG.  10   , the lower closing seal member  45  is anchored in a lower surface of the actuating ring  31  and is extending vertically downwards. The cooperating surface is the vertical edge  61  of the bottom plate  23 . In particular, such a configuration is interesting in that the bottom plate can be provided with a limited diameter. 
     However, the disclosure shall also encompass embodiments in which the lower closing seal member is fixed to the bottom of the radially outer wall of the actuating ring and the associated cooperating surface is the vertical edge of the bottom plate. The disclosure also encompasses embodiments in which the lower closing seal member is fixed to the bottom plate and the associated cooperating surface is the radially outer wall of the actuating ring. 
     Variations in the present invention are possible in light of the description of it provided herein. While certain representative embodiments and details have been shown for the purpose of illustrating the subject invention, it will be apparent to those skilled in this art that various changes and modifications can be made therein without departing from the scope of the subject invention. It is, therefore, to be understood that changes can be made in the particular embodiments described which will be within the full intended scope of the invention as defined by the following appended claims.