Vulcanization mold for a commercial vehicle tire and commercial vehicle tire vulcanized therein

Abstract

Vulcanization mold for vulcanizing a commercial vehicle tire, which is provided with a tread, sidewalls and bead areas, wherein the mold has a segment ring (2) forming the tread, bead rings (3) forming bead areas with inner surfaces (7) and sidewall shells (1) forming sidewalls with, with respect to the interior (4) of the vulcanization mold, outwardly curved, identically designed inner surfaces (6), wherein the interior space (4) between the side wall shells (1) has its location with the largest inner diameter (d1) and wherein the inner surfaces (7) of the bead rings (3) and the inner surfaces (6) of the side wall shells form the inner contour of the vulcanization mold, wherein the inner contour has a first contour section (6'b) extending radially inward from the point with the largest inner diameter (d1), a second contour section (6''b) and a transition section (7a) adjoining the second contour section and curved in the opposite direction in cross-section, wherein, viewed in cross-section, the inner contour of the vulcanization mold has an inflection point (P1) at the boundary between the second contour section (6''b) and the transition section (7a), wherein a tangent (t1) running through the inflection point (P1) and applied to the inner contour runs at an angle (α) of at least 46.2° to the axial direction (A), characterized in that, viewed in cross-section,the first contour section (6'b) runs along a circular arc with a first radius (r1) and the second contour section (6''b) runs along a circular arc with a second radius (r2), wherein the first radius (r1) is greater than the second radius (r2), wherein the radius (r2) of the circular arc of the second contour section (6''b) is at least 31.0 mm, in particular at least 40.0 mm, and preferably at least 44.8 mm.,

Description

[0001] The invention relates to a vulcanization mold for vulcanizing a commercial vehicle tire, which is provided with a tread, sidewalls and bead areas, wherein the mold has a segment ring forming the tread, bead rings with inner surfaces forming bead areas and sidewall shells forming sidewalls with, with respect to the interior of the vulcanization mold, outwardly curved, identically designed inner surfaces, where the interior space between the side wall shells has its point with the largest inner diameter and wherein the inner surfaces of the bead rings and the inner surfaces of the side wall shells form the inner contour of the vulcanization mold, wherein the inner contour has a first contour section extending radially inward from the point with the largest inner diameter, a second contour section and a transition section adjoining the second contour section and curved in the opposite cross section.

[0002] The use of vulcanization molds for the vulcanization of vehicle tires is disclosed, for example, in US 2013 / 0323 342 A1 or DE 32 02 008 A1. Commercial vehicle tires vulcanized in known vulcanization molds occasionally exhibit superficial damage or surface defects in the lower and central regions of the sidewalls and the outer bead areas. The occurrence of this damage is usually due to the material distribution of the various materials in these areas in the bead areas and sidewalls of the tire, as well as to the dynamic processes that occur during molding and heating of the green tire. Other causes that can lead to the occurrence of such damage include spray solutions in the vulcanization mold and residues from previously vulcanized tires.If such damage occurs, the tire must be reworked after vulcanization or even rejected. Such vulcanization methods therefore do not allow commercial vehicle tires to be vulcanized to the consistently high quality desired, which also increases overall production costs. Furthermore, any rework on the already vulcanized tire may not replicate the actual tire contour to the desired extent, so the tire's properties may suffer in this case as well.

[0003] The invention is based on the object of designing a vulcanization mold of the type mentioned above in such a way that the vulcanized commercial vehicle tires no longer have any surface damage in the lower sidewall and the adjacent bead areas, so that the tires are vulcanized with their actually intended contour.

[0004] The stated object is achieved according to the invention according to claim 1 in that, viewed in cross section, the inner contour of the vulcanization mold has an inflection point at the boundary between the second contour section and the transition section, wherein a tangent to the axial direction passing through the inflection point and applied to the inner contour runs at an angle of at least 46.2°.

[0005] A vulcanization mold designed according to the invention is thus characterized by a special curvature or bulge in the radially inner region of the inner surfaces of the sidewall shells. Due to the two contour sections, the bulge between the point with the largest inner diameter of the interior and the bead rings is flatter, virtually smoothed, than the contours of known vulcanization molds. This, and the special curvature of the inner contour in the area around the turning point, make it easier to mold the green tires into the mold and also easier to demold. The different materials in the sidewall and bead areas can be vulcanized in such a way that surface damage is either eliminated or minimal, ensuring a high level of reproducibility of the vulcanization process.

[0006] According to a preferred embodiment, the angle at which the tangent passing through the inflection point of the inner contour extends to the axial direction is at least 48°, in particular 49.4° ± 0.2°. This measure contributes to a flatter design of the curvature at the transition area between the sidewall shell and the bead ring and therefore supports the achievement of the above-mentioned effects.

[0007] In this context, it is further preferred if the angle at which the tangent passing through the turning point of the inner contour runs to the axial direction is at most 60°, in particular at most 55°.

[0008] It is also preferred if the inner contour between the point with the largest inner diameter of the interior and the inner surfaces of the bead rings is composed of the first contour section and the second contour section. This particularly advantageously "smoothes" the inner contour of the vulcanization mold with regard to easy demolding of the vulcanized tire.

[0009] It is also advantageous in this context if the first contour section and the second contour section connect to each other without kinks in cross-section.

[0010] According to the invention, viewed in cross section, the first contour section runs along a circular arc with a first radius and the second contour section runs along a circular arc with a second radius, wherein the first radius is larger than the second radius.

[0011] According to the invention, the contour of the vulcanization mold in the second contour section of the side wall shell immediately adjacent to the bead ring is designed such that the radius of the circular arc of the second contour section is at least 31.0 mm, in particular at least 40.0 mm and preferably at least 44.8 mm.

[0012] In connection with a flatter, quasi-smoothed design of the inner contour of the vulcanization mold, it is also particularly preferred if the transition section of the inner surface of the bead rings, viewed in cross section, adjoins the second contour section without kinks, is curved inwards with respect to the interior of the vulcanization mold and runs along a circular arc with a third radius of 9.0 mm to 16.0 mm.

[0013] A further detail of the design of the inner contour of the vulcanization mold is advantageous for achieving the above-mentioned effects, namely that the distance determined in the radial direction between a first line which, viewed in cross section, runs in the axial direction through the inflection point of the inner contour of the vulcanization mold and a second line which, viewed in cross section, runs in the axial direction through a bead reference point which, on the commercial vehicle tire, at least substantially corresponds to the rim reference point, is 40.9 mm to 46.3 mm, in particular 41.7 mm to 45.9 mm and particularly preferably 43.0 mm to 44.6 mm.

[0014] The invention further relates to a commercial vehicle tire which has been vulcanized in a vulcanization mold according to one or more of claims 1 to 10.

[0015] Further features, advantages and details of the invention will now be explained with reference to the single figure, Fig. 1, which schematically shows a cross-section through a closed vulcanization mold for commercial vehicle tires, is described in more detail.

[0016] The invention relates to a vulcanization mold for a commercial vehicle tire, which is particularly suitable and intended for mounting on tapered shoulder and flat shoulder rims with a diameter of 15, 16, 17, 18 or 20 inches.

[0017] In the following description and in the claims, the terms “radial direction” and “axial direction” as well as “radial” and “axial” refer to the directions present on the tire being vulcanized in the vulcanization mold. Fig. 1, the axial direction is indicated by a double arrow A and the radial direction by a double arrow R. The description and claims further refer to the vulcanization mold in the closed state, as in Fig. 1 shown.

[0018] According to Fig. 1, the vulcanization mold has sidewall shells 1 forming sidewalls, a segment ring 2 forming the tread, and bead rings 3 forming bead regions. The vulcanization mold can be opened and closed in a known manner, wherein the Fig. 1 upper side wall shell 1 from the Fig. 1 lower sidewall shell 1 is movable, for example, in a vertical direction by means of a mechanism (not shown) for opening and closing the vulcanization mold. When the vulcanization mold is closed, the sidewall shells 1, the segment ring 2, and the bead rings 3 together form and delimit a cavity, which is referred to as the interior space 4.

[0019] The segment ring 2 has an inner surface 5 facing the interior 4, which is provided, for example, in a known manner (not shown), with profile ribs forming grooves in the tread and with lamella plates forming incisions in the tread. The sidewall shells 1 each have an outwardly curved inner surface 6 facing the interior 4. The bead rings 3 have inner surfaces 7, which form the outer sides of the bead areas during vulcanization.

[0020] The interior space 4 has its largest inner diameter d1 in the central region of the sidewall shells 1. Beginning at and radially outside the point with the largest inner diameter d1, the inner surface 6 of each sidewall shell 1 has a radially outer surface section 6a extending to the inner surface 5 of the segment ring 2, and beginning at and radially inside the point with the largest inner diameter d1, a radially inner surface section 6b extending to the inner surface 7 of the bead ring 3. The radially outer surface section 6a and the radially inner surface section 6b adjoin one another at the point with the largest inner diameter d1, viewed in cross-section.

[0021] The radially inner, outwardly curved surface section 6b is composed of an outer contour section 6'b starting from the point with the largest inner diameter d1 and an inner contour section 6"b ending at the respective bead ring 3. The outer contour section 6'b therefore runs, with respect to the radial direction R, radially further outwards than the inner contour section 6''b.

[0022] Viewed in cross-section, the outer contour section 6'b is rounded according to a circular arc with a radius r1, and the inner contour section 6''b is rounded according to a circular arc with a radius r2, which is smaller than the radius r1. The radius r2 is at least 31.0 mm, in particular at least 40.0 mm, and preferably at least 44.8 mm. A section, approximately half of the radially outer surface section 6a, is also rounded according to the selected radius r1. In a mold for vulcanizing a commercial vehicle tire intended for a 16-inch rim, the radius r2 is, for example, 40.0 mm. The arc lengths of the outer contour section 6'b and the inner contour section 6''b, as well as the sizes of the radii r1, r2, present in the cross-section, are selected and coordinated such that the two contour sections 6'b, 6''b adjoin one another without kinks. Fig. 1, a point P1 is also shown at the boundary between the inner contour section 6''b and the inner surface 7 of the bead ring 3.

[0023] The inner contour section 6''b is designed such that a tangent t1 passing through point P1 and applied to the inner contour section 6''b forms an angle α of at least 46.2°, in particular of at least 48°, and preferably of 49.4° with a line l1 running in the axial direction. If the radius r2 is at least 40.0 mm, it is preferred if the angle α is at least 48°. If the radius r2 is at least 44.8 mm, it is preferred if the angle α is at least 49.4°. Vulcanization molds according to these variants enable the production of particularly high-quality tires, thus ensuring the desired performance characteristics and driving properties of the tire.

[0024] The inner surface 7 of the bead ring 3 is designed according to the outer contour of the bead area to be formed during vulcanization and has a transition section 7a adjoining the inner contour section 6''b and further a contour section 7b forming the bead seat surface. The transition section 7a, viewed in cross-section, runs along a circular arc with a radius r3 of 9.0 mm to 16.0 mm and is curved inward relative to the interior space 4. The radius r2 of the inner contour section 6''b and the radius r3 of the transition section 7a are coordinated such that the inner contour section 6''b and the transition section 7a, viewed in cross-section, adjoin one another without kinks. The point P1 therefore represents an inflection point of the inner contour of the vulcanization mold.

[0025] In Fig. 1, a bead reference point P2 corresponding to the rim corner reference point on the commercial vehicle tire is shown at the axially and simultaneously radially outer end of the contour section 7b. The bead reference point P2 is known to be the point on the outer side of the bead area of ​​the commercial vehicle tire at which the radially inner end of the rim radius is located when the commercial vehicle tire is mounted on the rim. As is known, due to the vulcanization process, the outer contour of the bead area of ​​the commercial vehicle tire may deviate slightly from the exact contour of the inner surface 7 of the bead ring 3, so that the rim corner reference point and the bead reference point do not have to coincide exactly and therefore at least largely coincide.

[0026] A line l2 running in the axial direction (double arrow A) is drawn through the bead reference point P2. Fig.1 The distance Δl determined in the radial direction (double arrow R) between the already mentioned line l1 and the line l2 is 40.9 mm to 46.3 mm, in particular 41.7 mm to 45.9 mm, and particularly preferably 43.0 mm to 44.6 mm.

[0027] If the vulcanization mold is intended for vulcanizing a commercial vehicle tire designed for a 16-inch rim, it is preferred if the angle α is 49.4° ± 0.2° and the distance Δl is 44.3 mm.

[0028] The invention is not limited to the described embodiments. The division of the vulcanization mold between the bead rings 3 and the sidewall shells 1 can be selected differently from the illustration shown. For example, the mold division can occur in the region of the radius r3 of the transition section 7a or in another region of the inner surface 7 of the bead ring 3 radially outside the bead reference point P2. Furthermore, the mold division can occur in the region of the radius r2 of the inner contour section 6''b, in the region of the radius r1 of the outer contour section 6'b, or at the kink-free transition of the outer contour section 6'b to the inner contour section 6''b.

[0029] The selection of the size of the radii r1, r2, r3, and the angle α directly impact the product's performance characteristics and enable consistently high production quality. With the aforementioned sizes of the radii r1, r2, r3 and the aforementioned size of the angle α, other criteria become more important when selecting the position of the mold split between sidewall shell 1 and bead ring 3, such as the standardization of the bead rings in production, the manufacturing costs of sidewall shells and bead rings, and other factors that influence production efficiency. List of reference symbols 1 side wall shell 2 segment ring 3 bead ring 4 Interior 5 inner surface 6 inner surface 6a radial outer surface section 6b radial inner surface section 6'b outer contour section 6''b inner contour section 7 inner surface 7a transition section 7b Contour section d1 largest inner diameter l1, l2 line Δl distance r1, r2, r3 radius t1 tangent A Double arrow (axial direction) P1 point P2 Bead reference point R Double file (radial direction) α angle

Claims

[1] Vulcanization mold for vulcanizing a commercial vehicle tire, which is provided with a tread, side walls and bead areas, wherein the mold has a segment ring (2) forming the tread, bead rings (3) with inner surfaces (7) forming bead areas and side wall shells (1) forming side walls with, with respect to the interior (4) of the vulcanization mold, outwardly curved, identically designed inner surfaces (6), wherein the interior space (4) between the side wall shells (1) has its location with the largest inner diameter (d1) and wherein the inner surfaces (7) of the bead rings (3) and the inner surfaces (6) of the side wall shells form the inner contour of the vulcanization mold, wherein the inner contour has a first contour section (6'b) extending radially inward from the point with the largest inner diameter (d1), a second contour section (6''b) and an adjoining transition section (7a) which is curved in the opposite direction in cross-section, wherein, viewed in cross-section, the inner contour of the vulcanization mold has an inflection point (P1) at the boundary between the second contour section (6''b) and the transition section (7a), wherein a tangent (t1) passing through the inflection point (P1) and applied to the inner contour runs at an angle (α) of at least 46.2° to the axial direction (A), characterized bythat, viewed in cross-section, the first contour section (6'b) runs along a circular arc with a first radius (r1) and the second contour section (6''b) runs along a circular arc with a second radius (r2), wherein the first radius (r1) is greater than the second radius (r2), wherein the radius (r2) of the circular arc of the second contour section (6''b) is at least 31.0 mm, in particular at least 40.0 mm, and preferably at least 44.8 mm. [2] Vulcanization mold according to claim 1, characterized by that the angle (α) at ​​which the tangent (t1) passing through the inflection point (P1) of the inner contour runs to the axial direction (A) is at least 48°. [3] Vulcanization mold according to claim 1 or 2, characterized by that the angle (α) at ​​which the tangent (t1) passing through the inflection point (P1) of the inner contour runs to the axial direction (A) is 49.4° ± 0.2°. [4] Vulcanization mold according to one of claims 1 to 3, characterized by that the angle (α) at ​​which the tangent (t1) passing through the inflection point (P1) of the inner contour runs to the axial direction (A) is at most 60°, in particular at most 55°. [5] Vulcanization mold according to one of claims 1 to 4, characterized by that the inner contour between the point with the largest inner diameter (d1) of the interior (4) and the inner surfaces (7) of the bead rings (3) is composed of the first contour section (6'b) and the second contour section (6''b). [6] Vulcanization mold according to one of claims 1 to 5, characterized by that the first contour section (6'b) and the second contour section (6''b) adjoin one another without kinks in cross-section. [7] Vulcanization mold according to one of claims 1 to 6, characterized bythat the transition section (7a) of the inner surface (7) of the bead rings (3), viewed in cross section, adjoins the second contour section (6''b) without kinks. [8] Vulcanization mold according to one of claims 1 to 7, characterized by that the transition section (7a) of the inner surface (7) of the bead rings (3), viewed in cross-section, is curved inwards with respect to the interior of the vulcanization mold. [9] Vulcanization mold according to one of claims 1 to 8, characterized by that the transition section (7a) of the inner surface (7) of the bead rings (3), viewed in cross section, runs along a circular arc with a third radius (r3) of 9.0 mm to 16.0 mm. [10] Vulcanization mold according to one of claims 1 to 9, characterized bythat between a first line (l1), which, viewed in cross section, runs in the axial direction (A) through the inflection point (P1) of the inner contour of the vulcanization mold, and a second line (l2), which, viewed in cross section, runs in the axial direction (A) through a bead reference point (P2) which, on the commercial vehicle tire, at least substantially corresponds to the rim corner reference point, there is a distance (Δl) determined in the radial direction (R), which distance is 40.9 mm to 46.3 mm, in particular 41.7 mm to 45.9 mm and particularly preferably 43.0 mm to 44.6 mm. [11] Commercial vehicle tyre which has been vulcanised in a vulcanisation mould according to one or more of claims 1 to 10.

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