Method for producing a vehicle tire

Abstract

The invention relates to a method for producing a vehicle tire with a radially inner and a radially outer air chamber (16, 18) which are integrally connected to one another, comprising the steps - applying an inner layer and at least one carcass ply to a tire building drum rotatable about a horizontal axis to form a carcass (14); - wrapping the circumference of the carcass (14), with the exception of the annular end regions thereof lying outward in the direction of the horizontal axis, with a separating layer (15) made of a material which prevents adhesion to one of the surfaces of the separating layer (15); - applying tire cores (10) to the annular end regions and folding the carcass (14) around the tire cores (10); - applying at least one belt layer (120), optionally without or with at least one layer of (spool) bandage and a tread (13) to form a belt package (12) to the carcass (14) wrapped by the separating layer (15) with at least partial wrapping of the end regions thereof; - pre-connecting the carcass (14) and the belt package (12) outside the areas enclosed by the separating layer (15) to form a green tire with an inner and an outer tire part and introducing a side valve (17) in the area of ​​the later sidewall (11) of the vehicle tire (1) to be formed from the green tire; and - shaping and vulcanizing the green tire in a vulcanization press to form the vehicle tire (1), wherein the separating layer (15) is formed by a vulcanizable elastomer strip which is pre-vulcanized in the region of its surface facing the belt package (12) or the carcass (14) over a partial region of its strip thickness by the action of electron beams or electromagnetic radiation, in such a way that it does not adhere to the adjacent surface of the belt package (12) or the carcass (14) in the region of its pre-vulcanized surface during vulcanization of the green tire.

Description

The invention relates to a method for manufacturing a vehicle tire having a radially inner and a radially outer air chamber which are integrally connected to one another, comprising the steps ofapplying an inner layer and at least one carcass ply to a tire building drum rotatable about a horizontal axis to form a carcass;wrapping the periphery of the carcass, except for the annular end portions thereof which are outwardly disposed in the direction of the horizontal axis, with a release liner of a material preventing adhesion to one of the surfaces of the release liner;applying tire cores to the annular end regions and turning the carcass around the tire cores;applying at least one belt ply and one tread strip for forming a belt package to the carcass wrapped by the separating ply with at least partial wrapping of the end regions thereof;pre-bonding the carcass and the belt package outside the regions wrapped by the release ply to form a tyre blank having an inner and an outer tyre part and introducing a side valve in the region of the subsequent side wall of the vehicle tyre to be formed from the tyre blank; andforming and vulcanizing the tire blank in a vulcanization press to form the vehicle tire.Vehicle tires of this type having a radially inner and a radially outer air chamber are known, for which reference is made, for example, to U.S. Pat. No. 1,294,622 A.Such vehicle tires provided with a radially inner and a radially outer air chamber are distinguished by an increased tire durability and by a filling pressure which can be adjusted independently of one another in the region of the radially inner and the radially outer air chamber, as a result of which the driving properties of the vehicle tire can be variably adjusted.For example, vehicle tires for passenger cars in the North Country market segment have high requirements for snow performance and especially ice performance, because they are intended for use in regions where the roads are often continuously covered with snow and ice for several months. A maximum ice grip is usually achieved by a wide footprint of the vehicle which is short in the direction of travel, since in this way the largest region of fresh ice can be gripped by the profile blocks in the footprint. However, such a high ice grip is usually associated with a relatively poor aquaplaning property on asphalt. Moreover, common vehicle tires for the North market often have low depth tread structures sufficient for a few 10,000 km on the vehicle tire when it is merely driven on snow and ice, but subject to severe wear when they are driven too long on asphalt, for example at the beginning and end of the winter season.A construction of a vehicle tire having a radially inner and a radially outer air chamber integrally connected to each other can improve the aquaplaning properties on asphalt while enabling maximum ice grip. The radially inner air chamber serves as a load-bearing part of the tire, while the belt package with the tread making contact with the roadway is arranged on the radially outer air chamber and the radially outer air chamber is filled with a lower air pressure than the radially inner air chamber, wherein this air pressure of the radially outer air chamber can be varied depending on the roadway condition. Higher air pressure is used for wet asphalt to provide maximum aquaplaning properties, while on ice-covered roads, air pressure can be reduced to provide maximum footprint without having to accept constraints on the load carrying capacity of the vehicle tire.Moreover, such vehicle tires having a radially inner and a radially outer air chamber can be easily retread and thus achieve longer service lives, since the radially outer air chamber protects the carcass and thus the radially inner air chamber when a worn tread is cut off. This can thus be provided with a new tread and used further, optionally even several times. In this way, significantly less waste is produced compared to at least two conventional tires at substantially the same running performance.Despite these advantages of a vehicle tire designed with a radially inner and a radially outer air chamber, this design has not yet been able to be adopted, since its production is very demanding. In the production method disclosed in U.S. Pat. No. 1,294,622 A, an inner carcass is first built up on a tire building drum, this inner carcass defining the later radially inner air chamber, and a separating layer is applied to the carcass, which may consist of an adhesion-reducing material such as zinc stearate or a non-adhering butyl cement, a pulverulent substance such as talc or else paper or fabric webs. The handling of these materials during tire construction is extremely complex, less reproducible and frequently associated with a corresponding impairment of the working environment, in particular when using pulverulent materials.It is therefore the object of the present invention to propose a method for producing a vehicle tire having a radially inner and a radially outer air chamber of the type mentioned at the beginning, which method can be applied in a simple manner to a conventional tire construction machine and overcomes the disadvantages of the prior art by virtue of the fact that such a vehicle tire can be produced reproducibly in high quality.To achieve the object set, the embodiment of a method according to the features of claim 1 is proposed according to the invention.Advantageous embodiments and developments of the invention are the subject matter of the dependent claims.The invention proposes that the release layer is formed by a vulcanizable elastomer strip which, in the region of its surface facing the belt package or the carcass, is prevulcanised over a partial region of its strip thickness by the action of electron or infrared radiation, in such a way that, in the region of its prevulcanised surface, it does not enter into any adhesion with the adjacent surface of the belt package or the carcass during vulcanization of the tyre blank.Such prevulcanization of the surface of the release liner by the action of electron or infrared radiation over a portion of the strip thickness reliably prevents a further vulcanization-induced connection to the adjoining layer on the surface treated in this way during the molding and vulcanization of the tire blank to form the vehicle tire, so that the radially inner and radially outer air chamber forms in the desired manner.Depending on the embodiment of the invention, the release ply can be placed as a vulcanizable elastomer strip on the carcass already built up on the tire building drum and can be prevulcanised in the region of the radially outwardly facing surface facing the belt package to be formed thereon. Alternatively, the separating layer can also be prevulcanised in the region of its surface to be applied to the carcass.The respectively opposite, non-pre-vulcanized surface of the release layer made of the vulcanizable elastomer strip thus does not lose its vulcanization property and thus, during molding and vulcanization of the tire blank in a vulcanization press, connects to the further layer of the belt package or of the carcass adjacent thereto, so that adhesion is prevented only in the region of the pre-vulcanized surface.The prevulcanization can be effected according to a proposal of the invention by irradiating the surface of the separating layer with electron beams or laser light. The radiation energy required for this purpose can be adjusted accordingly by the skilled person depending on the elastomer material used and the thickness and the desired depth extension of the partial region of the total thickness of the strip in which the prevulcanization is to take place. Infrared lasers are suitable, for example, for irradiation with laser light.According to a further proposal of the invention, the separating layer is designed with a strip thickness of about 0.75 to 2 mm and prevulcanised from a surface to a depth of about 0.5 mm. The width of the separating layer can correspond at least to the full width of the belt package or can be joined together from a plurality of joined sections of smaller width to form a corresponding overall width.According to a further proposal of the invention, the separating layer can be prevulcanised after being laid on the carcass on the tyre building drum by a corresponding irradiation device being pivoted onto the tyre building drum or, according to an alternative proposal, can be prevulcanised already before being supplied to the tyre building drum, for example before or after the separating layer has been cut to form a required length section for producing a vehicle tyre according to the invention.The at least one belt ply applied according to the invention to the carcass can optionally be embodied without or with at least one ply of a (winding) bandage or comprise the latter.Further embodiments and details of the invention are explained below with reference to an exemplary embodiment in the drawing.The single FIG. 1 shows a schematic representation of a cross section through a vehicle tire 1 produced according to the method according to the invention, which is arranged on a conventional rim 2 in a manner known per se with its tire cores 10 arranged radially on the inside in corresponding receiving grooves 21 of the rim 2 delimited by rim flanges.To produce this vehicle tire 1, a green tire is first produced in a manner known per se on a tire construction plant. For this purpose, in a first step, a carcass 14 is built up on a tire building drum which can be rotated about a horizontal axis and which has an inner layer and at least one carcass ply in a manner not shown in more detail.Then, on the carcass 14 thus formed, a release liner 15 is applied which is sized and positioned to wrap the carcass 14 except for the outer annular end portions thereof in the horizontal axis direction.The separating layer 15 can be formed, for example, from a vulcanizable elastomer strip having a thickness of 0.75 to 2 mm, which is irradiated with electron beams in the region of its radially outward-facing surface already before being fed to the tire building drum and is prevulcanized to a depth of about 0.5 mm by the action of the electron beams. The release layer 15 is therefore only still unvulcanized in the region of its surface facing the carcass 14 and is capable of a subsequent vulcanization with the accompanying indivisible adhesion to the carcass 14.Then, tire cores 10 and, if appropriate, apex profiles and the like are applied to the regions of the carcass 14 not enclosed by the release layer 15, and also, if appropriate, additional rubber strips for forming the subsequent side walls 11 of the vehicle tire 1, the carcass 14 is additionally folded around the tire cores 10 and brought into contact with the strips for forming the side walls 11 in the form of a carcass high impact.Subsequently, in a manner known per se, at least one belt ply, optionally without or with at least one ply (winding) bandage, and the radially outer tread 13 are applied to the carcass 14, which is additionally wrapped with the release ply 15, in order to form a belt package 12, wherein the width is dimensioned such that at least a part of the end regions of the carcass 14 not wrapped by the release ply 15 is covered. In addition, a side valve 17 is introduced in the region of the later side wall 11 of the vehicle tire 1 to be formed from the green tire. The carcass-side belt ply is representatively identified in FIG. 1 by reference sign 120.The carcass 14 with belt package 12 thus formed on the tire building drum is pre-bonded to form a green tire outside the regions wrapped by the separating layer 15, wherein no bond can be produced between the carcass 14 and belt package 12 as a result of the pre-vulcanized surface of the separating layer 15 adjacent to the belt package 12, since this is prevented by the intermediate separating layer 15. The connection of the belt package 12 to the remaining part of the green tyre takes place for the most part via the side wall and via the part of the carcass 14 which is not covered by the release layer 15. The width of this part may vary depending on the embodiment.Subsequently, the green tire produced in this way is shaped in a known manner in a vulcanization press to form the vehicle tire 1 shown in FIG. 1, wherein the separating layer 15 does not enter into an adhesive bond along its surface facing the belt package 12 and already pre-vulcanized, but rather only connects to the underside of the carcass 14.In this respect, a pneumatic vehicle tire 1 is formed which has 2 independent air chambers divided from one another by the carcass 14 and the separating ply 15, namely a radially inner air chamber 16 which is closed via the rim 2 and can be filled with a pressure via the filling valve 20 which is present as standard in the rim 2, and the further air chamber 18 which is arranged radially on the outside and runs between the carcass 14 with the separating ply 15 and the belt package 12 and can be filled with a separately adjustable pressure via the side valve 17. Both air chambers 16, 18 are integrally connected to one another adjacent to the tire cores 10 in a connecting region 110, since no separating layer 15 is present in this region.To compensate for a rolling resistance increased by the additional components, lightweight components for the belt plies 120 and / or the tread 13, for example aramid fibers and / or monofilament steel wires, can be used in the region of the belt package 12. For the inner load-bearing carcass 14, a steel cord fabric can be used which gives the carcass 14 increased robustness with low rolling resistance and also increases the suitability for retreading.The production of the pneumatic vehicle tire designed in this way is thus significantly simplified and its service life is increased.List of reference numbers:1 Vehicle tire 2 rim 10 tire core 11 sidewall 12 belt package with (winding) bandage 13 tread 14 carcass 15 separator layer 16 radially inner air chamber 17 side valve 18 radially outer air chamber 20 filler valve 21 rim groove 110 connecting region 120 carcass-side belt layerReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedU.S. Pat. No. 1,294,622 A [0002, 0007]

Claims

A method of manufacturing a vehicle tire having radially inner and outer air chambers (16, 18) integrally connected to each other, comprising the steps of: applying an inner layer and at least one carcass ply to a tire building drum rotatable about a horizontal axis to form a carcass (14); enclosing the periphery of the carcass (14) except for the outer annular end portions thereof in the horizontal axis direction with a release liner (15) of a material preventing adhesion to one of the surfaces of the release liner (15); applying tire cores (10) to the annular end portions; and wrapping the carcass (14) around the tire cores (10); applying at least one belt ply (120) and a tread (13) for forming a belt package (12) to the carcass (14) wrapped by the release ply (15) with at least partial wrapping of the end regions thereof; preconnecting the carcass (14) and the belt package (12) outside the regions wrapped by the release ply (15) to form a tyre blank having an inner and an outer tyre part and introducing a side valve (17) in the region of the subsequent side wall (11) of the vehicle tyre (1) to be formed from the tyre blank; and - forming and vulcanizing the tire blank in a vulcanization press to form the vehicle tire (1); characterized in that the release layer (15) is formed by a vulcanizable elastomer strip which, in the region of its surface facing the belt package (12) or the carcass (14), is prevulcanized over a partial region of its strip thickness by the action of electron beams or electromagnetic radiation, in such a way that, in the region of its prevulcanized surface, it does not enter into any adhesion with the adjacent surface of the belt package (12) or the carcass (14) during vulcanization of the tire blank.Method according to Claim 1, characterized in that the separating layer (15) is irradiated with infrared radiation or laser light, in particular infrared laser light, in the region of one of its surfaces and prevulcanised.Method according to either of Claims 1 and 2, characterized in that the separating layer (15) has a strip thickness of 0.75 to 2 mm and is prevulcanised starting from a surface to a depth of up to 0.5 mm.Method according to one of Claims 1 to 3, characterized in that the separating layer (15) is prevulcanised on the tyre building drum after it has been laid on the carcass (14).Method according to one of Claims 1 to 3, characterized in that the separating layer (15) is prevulcanised before it is fed to the tyre building drum.Method according to one of Claims 1 to 5, characterized in that the belt ply (120) comprises at least one ply of a (winding) bandage.

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