Vulcanization form and vulcanized vehicle tires

Abstract

Vulcanization mold for molding and vulcanizing vehicle tires, comprising molded parts for forming a tread of the tire, a pair of axially opposite sidewall shells (1, 2), a pair of axially opposite bead rings (3a, 3b) for molding the bead regions of the tire that come into contact with a rim, and an annular insert (5) in at least one sidewall shell (1), which insert is replaceably inserted into a molding of the sidewall shell (1) and has an inner surface (6) facing the mold cavity, which inner surface, together with the inner side of the sidewall shell, forms a base surface and shapes the relevant sidewall and the associated bead region of the vehicle tire. The insert (5) is inserted into the side wall shell (1) directly adjacent to the bead ring (3a), whereby the inner surface (6) of the insert (5) occupies 10% to 40% of the base surface (1a) and is covered with a PTFE layer (5a).

Description

The invention relates to a vulcanization mould for forming and vulcanizing vehicle tyres, comprising moulded parts for forming a tread of the tyre, a pair of axially opposite sidewall shells, a pair of axially opposite bead rings for forming the bead regions of the tyre coming into contact with a rim, and an annularly encircling insert in at least one sidewall shell, which insert is inserted in a replaceable manner into a formation of the sidewall shell and has an inner surface facing the mould cavity, which together with the inner side of the sidewall shell forms a base surface and forms the relevant sidewall and the associated bead region of the vehicle tyre.Such a vulcanization mold is known, for example, from EP 2 162 278 B1. On the inner sides of the sidewall shells, a respective annularly encircling groove is formed, into which an annular insert is introduced in a removable manner, the inner surface of which insert has graphic markings for embossing on the sidewall of the tire and projects beyond the inner sides of the sidewall shells. In this way, the tire molding and vulcanization process is to be improved with a particular focus on creating fundamental or decorative motifs on the sidewall. In particular, it should be possible to form different decorative motifs with one and the same vulcanization mold on the tire side wall.EP 1 382 426 B1 discloses a tire vulcanization mold with side wall shells, wherein at least one of the two side wall shells is provided with an inner side which, in particular by chromium plating, has a surface finish of less than 0.381 microns. The tire cured in the vulcanization mold therefore has at least one sidewall having a gloss reading greater than 10 measured using a 60° gloss reading per ASTM D523-89. The side wall should therefore have a surface layer which inhibits the migration of antioxidants from the rubber material and has a glossy black appearance.The object of the invention is to impart a particularly glossy black appearance to a partial area on at least one side wall of the vulcanized tire with a vulcanization mold of the type mentioned at the beginning, wherein a conventional side wall design with inscriptions, decorative elements, ornaments, logos and the like can be maintained at other areas of the side wall.The object set is achieved according to the invention in that the insert is inserted into the side wall shell directly adjoining the bead ring, wherein the inner surface of the insert takes up 10% to 40% of the base surface and is covered with a PTFE layer.As a result of the insert covered with PTFE on its inner surface, a smooth, glossy and therefore deep black circular ring is produced on the side wall immediately adjacent to the bead region during vulcanization of the tire, which ring is clearly lifted from the remainder of the side wall by its appearance. This ring is formed at a prominent location on the side wall, but leaves a large amount of space outside for the usual configuration of the side wall with inscriptions, decorative elements and the like. In lieu of this, after a larger number of vulcanization cycles, the replacement can be easily replaced by a new one.In a preferred embodiment, the inner surface of the insert occupies up to 30%, preferably up to 20%, of the base surface. In this way, a decent, but clearly visible, glossy circular ring is produced on the outer surface of the side wall of the tire vulcanized in this vulcanization mold, and there remains sufficient space for the formation of decoration, inscriptions and the like on the other region of the side wall.The PTFE layer located on the inner surface of the insert preferably has a thickness of 0.005 mm to 0.10 mm, in particular of 0.02 mm to 0.04 mm. A PTFE layer of this thickness allows a large number of vulcanization operations to be carried out without damage. A durable and thin PTFE layer is, for example, a layer of PTFE formed and sprayed on by heat treatment.In this embodiment, the PTFE layer is advantageously located on a polished or smoothed surface of the insert, so that the circular ring formed on the tire has a particularly high degree of gloss.Striking light / shadow effects can be produced by virtue of the fact that the PTFE layer is located on an inner surface of the insert which is structured overall, or in certain sections or on inner surfaces of the insert which are structured on surface elements.In an embodiment which is particularly advantageous in this regard, the structure consists of a multiplicity of ribs which run in particular parallel to one another and have a height of 0.10 mm to 0.80 mm, in particular 0.20 mm to 0.50 mm, at their highest point.An embodiment is furthermore particularly advantageous in which the structure of ribs running parallel to one another and having zigzag-shaped consecutive rib sections, wherein the rib sections each have an extension length which is 0.20 mm to 0.40 mm, in particular 0.25 mm to 0.30 mm, and wherein the ribs have lateral rib flanks which each run at an angle of up to 10°, in particular of 2° to 10°, to a perpendicular to the inner surface.In an alternative embodiment of the vulcanization mold, the PTFE layer is formed by a PTFE tape fastened to the insert. In order to be able to fasten the PTFE tape to the insert in a detachable manner, in particular from the rear side thereof, the PTFE tape has a certain thickness, for example in the order of magnitude of 5.00 mm to 10.00 mm.In a further preferred embodiment, the PTE layer is formed by a PTFE tape which is connected to an annular intermediate part which is detachably fastened, in particular screwed, to the insert. The PTFE tape may be bonded to the intermediate part by bonding.The invention further relates to a vehicle tyre, in particular a pneumatic vehicle tyre, having side walls and bead regions, which has been vulcanized in a vulcanization mould according to one or more of Claims 1 to 7. On at least one side wall, a circular ring having a higher degree of gloss than the rubber materials of the remaining side wall and of the bead region and encircling it is formed directly adjoining the bead region.Further features, advantages and details of the invention will now be described in more detail with reference to the schematic drawing which represents an exemplary embodiment. Figure shows FIG. 1 is a partial sectional view of a tire vulcanizing mold in a closed state, FIG. 2 is a schematic side view of a tire vulcanized in this vulcanization mold.FIG. 1 schematically shows components of a conventional vulcanization mold for a pneumatic vehicle tire, for example for passenger cars. Only components in one half of the vulcanization mold are shown. The vulcanization mold is located within a heating press, the components of which are not shown, and which usually has a press top and a press bottom, and also mechanisms for positioning the tire to be vulcanized, for actuating the vulcanization mold, for introducing the heating medium and for removing the completely vulcanized tire.In FIG. 1, of the vulcanization mold, a lower sidewall shell 1 forming the one sidewall of the tire and an upper sidewall shell 2 forming the second sidewall of the tire, a lower bead ring 3a and an upper bead ring 3b, and a mold segment 4 of a usual segmented ring consisting of, for example, six to eight total annularly surrounding mold segments are shown. Of the side wall shells 1, 2 and the bead rings 3 a, 3 b, only one half can be seen in each case in the section according to FIG. 1. The upper side wall shell 2 is arranged together with the upper bead ring 3b, for example, on a heating plate, not shown, and is removable for opening and closing the vulcanization mold. The mould segments 4 of the segmented ring are provided on the inside with profile inserts, not shown, which form a profiled tread of the tyre, not shown, and can be radially extended and moved together for opening and closing the vulcanization mould.The bead rings 3a, 3b are known to form those regions of the pneumatic vehicle tire which come into contact with the latter during the mounting of the tire on a rim. On the inner sides of the sidewall shells 1, 2 are included those structures which cause decoration, ornaments, logos, inscriptions and the like to be formed on the sidewalls of the tire. Between the bead ring 3 a, 3 band the shaped segments provided for forming the running surface, there is in each case a base surface 1 a, 2 a, which follows the curvature or inner contour and from which the mentioned structures are formed as elevations or depressions. FIG. 1 shows only the base surfaces 1 a, 2 awithout such structures.In the embodiment shown, an insert 5 of circular ring-like configuration is inserted into the lower side wall shell 1 directly adjacent to the bead ring 3a. Before the positioning of the bead ring 3 a, the insert 5 is inserted into a correspondingly milled-out formation on the side wall shell 1, for example, and is fastened by means of screws from the outer side of the side wall shell 1 in a removable or exchangeable manner. Subsequently, the bead ring 3a is positioned and also fixed to the lower side wall shell 1 by means of screws.The insert 5 which extends all the way round in the lower side wall shell 1 in the manner of a ring has an inner surface 6 which faces the mold cavity and which also delimits the latter in the shape of a circular ring and which preferably fits into the immediately adjoining regions of the inner sides of the side wall shell 1 and of the bead ring 3a at the same level. In an alternative embodiment, the insert 5 projects beyond the immediately adjoining regions of the inner sides of the sidewall shell 1 and of the bead rings 3 aby in particular 0.50 mm to 2.00 mm and therefore forms a corresponding annularly encircling depression on the sidewall of the tire.The insert 5 is preferably designed in such a way that its circular ring-shaped inner surface 6 covers 10% to 40%, in particular 30%, preferably to 20%, of the base surface 1a present between the bead ring 3a and the shaped segments 4 of the segment ring, consisting of the inner surface 6 and the remaining inner side of the side wall shell 1 and in particular continuous in a uniform manner.In a preferred embodiment, the insert 5 is made as a turned part of steel and is sprayed on its surface subsequently forming the inner surface 6 with a commercially available PTFE (polytetrafluoroethylene) coating spray, a so-called spray & bake PTFE. The sprayed PTFE is cured in a heat treatment and then forms a thin and solid PTFE layer 5 ato 0.10 mm, in particular 0.02 mm to 0.04 mm. Such a PTFE spray is available, for example, under the designation Teflon™ Coating Spray from Toefco Engineered Coating Systems, Inc., see https: / / toefco.com / teflon-coating-spray / (called on 12.07.2023). Subsequently, the insert 5 is installed in the side wall shell 1. The relevant surface of the insert 5 can be polished or smoothed before spraying.In an alternative embodiment, a PTFE tape is fastened circumferentially in the form of a circular ring on the insert 5 in a thickness suitable for screwing on, or a separate intermediate part in the form of a circular ring, for example made of metal, is produced with a PTFE tape as a support and fastened to the insert 5, in particular screwed to the latter.FIG. 2 shows a side view of a pneumatic vehicle tire vulcanized in the vulcanization mold in a side view having a side wall 7 and a bead region 8, The insert 5 has formed on the side wall 7 of the tire a smooth and glossy circular ring 9 which appears darker than the surrounding rubber material and which directly adjoins the bead region 8, so that this circular ring 9 directly adjoins the rim when the tire is mounted on a rim.In vehicle tires provided for multi-lane motor vehicles, such a circular ring 9 is formed at least on one side wall, in the case of tires having a specific mounting position on that side wall which, when the tire is mounted, faces the outside of the vehicle. Alternatively, during tire assembly, it can be ensured that the side wall 7 provided with the circular ring 9 is located on the outside. Moreover, it is possible to install inserts as described on both side wall shells 1, 2 and to form circular rings 9 on both side walls 7.In a further possible embodiment, the insert 5 has a structured inner surface produced in particular by means of laser engraving. In one possible embodiment, the inner surface is uniformly structured overall or alternatively in certain sections or on surface elements. The structure consists, for example, of ribs running parallel to one another or substantially parallel to one another in zigzag form and forming a hatching, wherein the rib sections each have an extension length which is 0.20 mm to 0.40 mm, in particular 0.25 mm to 0.30 mm. The ribs have lateral rib flanks which each extend at an angle of up to 10°, in particular of 2° to 10°, to a perpendicular to the inner surface. The ribs have a height at their highest point which is 0.10 mm to 0.80 mm, in particular 0.20 mm to 0.50 mm. An embodiment of such a structure is known, for example, from DE 10 2021 212 509 A1. In this structure, a freely terminating additional rib branches off in each case on the same side of the hatching ribs and starting from inner corner regions.List of reference characters1 Lower side wall shell 2 Upper side wall shell 1 a, 2 aBase surface 3 a, 3 b Wulst ring 4 Shaped segment 5 Insert 5 a PTFE layer 6 Inner surface 7 Side wall 8 Bead region 9 Circular ringReferences 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 citedEP 2 162 278 B1

[0002] EP 1 382 426 B1

[0003] DE 10 2021 212 509 A1

[0027]

Claims

Vulcanization mould for forming and vulcanizing vehicle tyres, comprising moulded parts for forming a tread of the tyre, a pair of axially opposite side wall shells (1, 2), a pair of axially opposite bead rings (3a, 3b) for forming the bead regions of the tyre coming into contact with a rim, and an annularly encircling insert (5) in at least one side wall shell (1), which insert is inserted in a replaceable manner into a formation of the side wall shell (1) and has an inner surface (6) facing the mould cavity, which together with the inner side of the side wall shell (1) forms a base surface (1a) and forms the relevant side wall and the associated bead region of the vehicle tyre, characterized in that the insert (5) is inserted directly adjacent to the bead ring (3a) subsequently into the side wall shell (1), wherein the inner surface (6) of the insert (5) occupies 10% to 40% of the base surface (1a) and is covered with a PTFE layer (5a).Vulcanization mould according to claim 1, characterised in that the inner surface (6) of the insert (5) occupies up to 30%, preferably up to 20%, of the base surface (1a).Vulcanization mould according to claim 1 or 2, characterised in that the PTFE layer (5a) located on the inner surface (6) of the insert (5) has a thickness of 0.005 mm to 0.10 mm, in particular of 0.02 mm to 0.04 mm.Vulcanization mold according to Claims 1 to 3, characterized in that the PTFE layer (5a) is the layer of a sprayed-on PTFE formed by heat treatment.Vulcanization mould according to claim 3 or 4, characterised in that the PTFE layer (5a) is located on a polished or smoothed inner surface (6) of the insert (5).Vulcanization mold according to claim 3 or 4, characterised in that the PTFE layer (5a) is located on an inner surface of the insert (5) which is structured overall or in certain sections or on inner surfaces which are structured on surface elements.Vulcanization mould according to claim 6, characterised in that the structure consists of a plurality of ribs, which extend in particular parallel to one another and which have a height of 0.10 mm to 0.80 mm, in particular 0.20 mm to 0.50 mm, at their highest point.Vulcanization mold according to claim 6 or 7, characterized in that the structure consists of ribs running parallel to each other in zigzag form and having successive rib sections, wherein the rib sections each have an extension length which is 0.20 mm to 0.40 mm, in particular 0.25 mm to 0.30 mm, and wherein the ribs have lateral rib flanks which each run at an angle of up to 10°, in particular 2° to 10°, to a perpendicular to the inner surface,Vulcanization mould according to one of Claims 1 to 3, characterized in that the PTFE layer is formed by a PTFE tape fastened to the insert (5).Vulcanization mould according to one of Claims 1 to 3, characterized in that the PTFE layer is formed by a PTFE tape which is connected to an annular intermediate part which is detachably fastened to the insert (5).Vehicle tyre, in particular pneumatic vehicle tyre, having side walls (7) and bead regions (8) which has been vulcanised in a vulcanization mould according to one or more of Claims 1 to 10, characterized in that a circumferential circular ring (9) which has a higher degree of gloss than the rubber materials of the remaining side wall (7) and of the bead region (8) and has a higher degree of gloss is formed on at least one side wall (7) directly adjoining the bead region (8).

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