Method for producing shaped segment

Abstract

The invention relates to a method for producing a forming section of a segmented vulcanization mold for vehicle tyres, wherein the forming surface of the forming section forms the tread profile of a section of the tyre to be vulcanized.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a forming segment of a segmented vulcanization mold for a vehicle tire, the forming surface of the forming segment shaping the tread pattern of a segment of the tire to be vulcanized.

[0002] Furthermore, the present invention relates to a forming segment and a vehicle tire, in which the surface tread of a sub-region of the forming segment is changed. Background Art

[0003] Vulcanization molds for tires mainly consist of forming parts that together form the radially outer surface (such as the tread), the shoulder region, the sidewalls, and the bead region of the tire. The segment that shapes the tread is called a forming segment or a shaping segment.

[0004] The term "boss tread" encompasses all incisions of the tread and possibly other incisions, such as those for inserting sheets into passenger car motor vehicle (PKW) tires and van tires.

[0005] An unvulcanized green tire blank is vulcanized in a vulcanization mold and converted to its final rubber-elastic state through a rubber crosslinking reaction. Here, the tread configuration of the tire is obtained through the corresponding concave configuration of the forming surface of the forming segment.

[0006] The forming surface refers to those surfaces of the forming segment that impart the corresponding configuration to the tire blank.

[0007] For tire performance, especially for the snow and ice performance of winter tires, it is advantageous that the crown surface of the tire tread (i.e., the surface tread of the vehicle tire) has a defined roughness. On the other hand, the grooves of the defined raised tread elements of the tread pattern should be as "smooth" as possible in order to give the tire a high-quality impression.

[0008] It is known from EP 3 261 830 B1 that the fine structure applied to a model segment by means of plasma coating is advantageous for the adhesion of the vehicle tire manufactured therewith under winter conditions. Summary of the Invention

[0009] Therefore, the object of the present invention is to provide a cost-effective and adaptable method for manufacturing a forming segment of a segmented vulcanization mold for a vehicle tire, and a forming segment of a segmented vulcanization mold for a vehicle tire, by means of which method and forming segment, a defined roughness or a defined surface tread can be provided for the crown tread surface of the tire to be vulcanized. Furthermore, the object of the present invention is to provide a vehicle tire having such a surface tread.

[0010] This object is achieved by a method according to the features of claim 1 and by a shaping segment and a vehicle tire according to the dependent claims. The dependent claims relate to particularly advantageous refinements of the invention.

[0011] Accordingly, the present invention provides a method for manufacturing a shaping segment of a segmented vulcanization mold for a vehicle tire, wherein the shaping surface of the shaping segment shapes the tread pattern of a segment of the tire to be vulcanized, the method comprising the following steps:

[0012] a) preparing a rigid model segment having a hood-shaped tread surface,

[0013] b) milling the convex tread of the tread into the hood-shaped tread surface of the model segment to produce a raw model, wherein the raw model has a surface tread to be changed at least in a certain sub-region,

[0014] c) preferably preparing a flexible mold on the raw model with silicone rubber,

[0015] d) preferably preparing a rigid mold on the mold, preferably made of silicone rubber, with plaster to form a casting core segment,

[0016] e) preferably casting all annular, adjoining casting core segments with an aluminum-magnesium alloy to obtain a vulcanization mold, and then dividing the vulcanization mold into individual shaping segments,

[0017] characterized in that,

[0018] the surface tread of the raw model is changed by ablation by means of laser radiation in such a way that the surface tread has an arithmetic mean height (Sa) greater than 5 μm and less than 100 μm according to ISO 25178.

[0019] The sub-region of the surface tread is understood to be exactly the region of one tread portion and the regions of the individual tread portions. The sub-region can also extend over the entire surface tread, where the surface tread is understood to be the region of the vehicle tire surface tread of the shaping segment that forms the vehicle tire.

[0020] It has been confirmed that by changing the surface tread pattern of a model segment to a specific roughness by means of laser radiation, vehicle tires can be achieved that solve the target conflict between dry grip and snow or ice grip at a higher level. This is due to the fact that in the case of a large contact area between the vehicle tire and the ground, which is particularly important for dry grip, a sufficient amount of concavity is also provided, and this concavity can be set so as to achieve high adhesion for snow or ice grip. Here, it has been confirmed that such roughness in the model segment can be produced in a particularly simple and cost-effective manner by means of laser radiation. In addition, it has been confirmed that when configuring the surface tread pattern, ablation by means of laser radiation can achieve a particularly high degree of freedom. For example, different surface tread patterns can be produced in different regions of the tread surface.

[0021] A preferred embodiment proposes that in step b), the surface tread pattern is changed by laser cutting or laser drilling. The ablation method carried out by means of laser radiation can achieve the production of a plurality of structures and surface roughnesses of different types and manners in a particularly simple way, and preferably only a partial surface of each model segment is processed.

[0022] Another preferred embodiment proposes that in step b), a structure size smaller than 0.1 mm × 0.1 mm is produced, in particular a surface tread pattern with Sa greater than 10 μm, preferably greater than 15 μm and / or less than 80 μm, preferably less than 60 μm. It has been confirmed that smaller structure sizes, in particular surface tread patterns with Sa greater than 10 μm and less than 80 μm, result in particularly good dry grip while contributing to particularly good values in terms of snow or ice grip.

[0023] Another preferred embodiment proposes that in step b), an Ssk value according to ISO 25178 greater than -10, preferably greater than -5, further preferably greater than -3 and / or less than 50, preferably less than 30, further preferably less than 20 is produced, and preferably an Sku value according to ISO 25178 of ≥ 3 is produced. It has been confirmed that the preferred Ssk value, which is also described as a depression in the plane (i.e., the generation of a height distribution above the average level), results in particularly good dry grip while contributing to particularly good values in terms of snow or ice grip.

[0024] Another preferred embodiment provides that in step b), the surface roughness Sa, Ssk and / or Sku is designed to be different in the circumferential direction from the shoulder region to the equator line and / or on each tread block. Designing the surface roughness of the equator line (i.e., the tread surface provided at the center between the shoulder regions) and the shoulder region to be different can achieve: generating surface roughnesses that are particularly suitable for the main functions of these regions in different lateral regions of the tread. Particularly effective adhesion in the circumferential and lateral directions is achieved. Therefore, the circumferentially variable main functions of the tread blocks can also be optimized.

[0025] Another preferred embodiment provides that in step b), the surface roughness Sa, Ssk and / or Sku is generated in the form of a defined pattern, preferably by means of dot matrices or vector cross-lines. It has been confirmed that setting the surface roughness in the form of dot matrices and vector cross-lines simultaneously, especially by means of dot matrices or vector cross-lines, can contribute to solving the mentioned objective conflicts at a higher level.

[0026] Another preferred embodiment provides that short-pulse laser radiation or ultrashort-pulse laser radiation is used as the laser radiation, and preferably the desired holes are generated. It has been confirmed that short-pulse laser radiation and ultrashort-pulse laser radiation are particularly suitable for generating particularly suitable surface treads and especially the desired holes, where these holes are understood as blind holes with a cross-section that is at least approximately circular.

[0027] Another preferred embodiment provides that the ablation of the surface tread by means of laser radiation is carried out by scanning the laser radiation multiple times, where the focal position of the laser radiation is preferably changed between scans and / or during each scan. Thereby, it is possible to generate suitable surface treads in a particularly simple and efficient manner.

[0028] According to the present invention, a forming segment of a segmented vulcanization mold for a vehicle tire is provided, where the forming surface of the forming segment forms the tread pattern of a segment of the tire to be vulcanized. The forming segment is preferably made by means of the method according to the present invention. The forming segment has at least one sub-region, where the at least one sub-region has an altered surface tread, which is obtained by ablating an original model by means of laser radiation. The surface tread of the original model is altered by ablation by means of laser radiation such that the forming segment has an arithmetic mean height (Sa) greater than 5 μm and less than 100 μm according to ISO 25178.

[0029] It has been confirmed that vehicle tires can be achieved with surface treads of formed segments having a roughness with an arithmetic mean height (Sa) greater than 5 μm and less than 100 μm, which are produced by ablating an original model with laser radiation and then molding, and these vehicle tires solve the target conflict between dry traction and snow or ice traction at a higher level.

[0030] According to the present invention, there is provided a vehicle tire which is preferably made by the method according to the present invention and / or made of formed segments according to the present invention, wherein the vehicle tire has at least one sub-region with a vehicle tire surface tread, and the vehicle tire surface tread has an arithmetic mean height (Sa) greater than 5 μm and less than 100 μm according to ISO 25178.

[0031] It has been confirmed that vehicle tires with a roughness having an arithmetic mean height (Sa) greater than 5 μm and less than 100 μm can solve the target conflict between dry traction and snow or ice traction at a higher level.

[0032] A preferred embodiment provides that the structural dimensions of the vehicle tire surface tread are less than 0.1 mm × 0.1 mm. In particular, the Sa of the vehicle tire surface tread is greater than 10 μm, preferably greater than 15 μm and / or less than 80 μm, preferably less than 60 μm. It has been confirmed that vehicle tire surface treads with smaller structural dimensions, especially those with Sa greater than 10 μm and less than 80 μm, contribute to particularly good values in terms of snow or ice traction while having particularly good dry traction.

[0033] Another preferred embodiment provides that the surface roughness Sa, Ssk and / or Sku of the vehicle tire surface tread is designed to be different in the circumferential direction from the shoulder region to the equator line and / or on each tread block. Designing the surface roughness of the equator line (i.e., the tread surface located at the center between the shoulder regions) and the shoulder region to be different can achieve: generating surface roughnesses particularly suitable for the main functions of these regions in different lateral regions of the tread. Particularly effective traction in the circumferential and lateral directions is achieved. Therefore, the circumferentially variable main functions of the tread blocks can also be optimized. Description of the Drawings

[0034] The present invention allows for various embodiments. To further clarify their basic principles, one of the embodiments is shown in the drawings and described below. In the drawings:

[0035] Figure 1 A circumferential section of a vehicle tire according to the present invention for a passenger motor vehicle is shown three-dimensionally in a sectional view, wherein a cutting plane containing the tire axis is shown; and

[0036] Figure 2 Shows a cross-section of the surface tread pattern. Detailed description

[0037] Figure 1 Shows a tubeless vehicle tire in a radial construction for a passenger motor vehicle, the vehicle tire having a tread 1 with tread pattern extending between the tire shoulders. Here, starting from the tire shoulders, tire sidewalls 2 are formed extending inwards in the radial direction R. The tread 1 with tread pattern and the tire sidewalls 2 are each designed to extend over the entire circumference of the vehicle tire in the circumferential direction U of the vehicle tire. Each tire sidewall 2 forms a bead area 4 at its radially inner end for fitting onto a rim. In the bead area 4, a tensile bead core 5 is formed concentric with the tire axis and extending over the entire circumference of the vehicle tire. In a known manner, the carcass 3 of radial construction starts from one bead core 5, extends outwards in the radial direction R through the tire sidewall 2 to the tread 1 with tread pattern, then extends axially through the extension area of the tread 1 with tread pattern to the other tire shoulder, and from there extends inwards in the radial direction R through the second tire sidewall 2 to the bead core 5 formed in the second bead area 4. The carcass 3 is formed in a known manner by one or more layers of carcass cords embedded in rubber. On the radially outer side of the carcass 3, a belt 6 consisting of a plurality of belt layers of a known type is formed in a known manner between the carcass 3 and the tread 1 with tread pattern, the belt extending over the entire circumference of the vehicle tire and extending in the axial direction A between the tire shoulders. The belt layers are formed by a reinforcing carrier embedded in rubber, such as steel cord or other known reinforcing carriers suitable for belts.

[0038] On the inner side of the carcass 3 facing the interior of the tire, a tire inner liner 7 made of a particularly airtight rubber material starts from one bead area 4 in a known manner, extends radially outwards along the tire sidewall 2 to the tire shoulder, then extends axially from the first tire shoulder to the second tire shoulder, and from there extends inwards in the radial direction along the second tire sidewall to the second bead area 4. The tire inner liner 7 extends over the entire circumference of the vehicle tire in the circumferential direction U.

[0039] In Figure 2 , a cross-section of the surface tread pattern 8 is shown, the height difference of these surface tread patterns from the highest point 9 to the lowest point 10 being 20 μm to 30 μm. As shown, the surface tread pattern 8 can have a rectangular or triangular geometry and combinations of these basic geometries. Here, the ratio of width to depth and the distance between individual depressions can vary.

Claims

1. A method for manufacturing a forming segment of a segmented vulcanization mold for a vehicle tire, wherein the forming surface of the forming segment shapes the tread pattern of a segment of the tire to be vulcanized, the method having the following steps: a) Preparing a rigid model segment having a hood-shaped tread surface, b) Milling the convex tread pattern of the tread (1) into the hood-shaped tread surface of the model segment to produce a raw model, wherein the raw model has a surface tread pattern (8) to be changed at least in a certain sub-region, c) Preferably preparing a flexible mold on the raw model with silicone rubber, d) On the mold preferably made of silicone rubber, preferably preparing a rigid mold with gypsum to form a casting core segment, e) Preferably casting all annular and adjoining casting core segments with an aluminum-magnesium alloy to obtain a vulcanization mold, and then dividing the vulcanization mold into individual forming segments, characterized in that, the surface tread pattern (8) of the raw model is changed by ablation by means of laser radiation in such a way that the surface tread pattern has an arithmetic mean height (Sa) greater than 5 μm and less than 100 μm according to ISO 25178.

2. The method according to claim 1, characterized in that, in step b), the surface tread pattern (8) is changed by laser cutting or laser drilling.

3. The method according to claim 1 or 2, characterized in that, In step b), a structural size of less than 0.1 mm × 0.1 mm is produced, in particular a surface tread pattern (8) with Sa greater than 10 μm, preferably greater than 15 μm and / or less than 80 μm, preferably less than 60 μm.

4. The method according to one of the preceding claims, characterized in that, In step b), an Ssk value greater than -10, preferably greater than -5, further preferably greater than -3 and / or less than 50, preferably less than 30, further preferably less than 20 according to ISO 25178 is produced, and preferably an Sku value of ≥ 3 according to ISO 25178 is produced.

5. The method according to any one of the preceding claims, characterized in that, in step b), the surface roughness Sa, Ssk and / or Sku is designed to be different in the circumferential direction from the shoulder region to the equator line and / or on each tread block.

6. The method according to one of the preceding claims, characterized in that, In step b), the surface roughness Sa, Ssk and / or Sku is produced in the form of a defined pattern, preferably by means of dot matrices or vector crossing lines.

7. The method according to one of the preceding claims, characterized in that, Short-pulse laser radiation or ultrashort-pulse laser radiation is used as the laser radiation, and preferably the desired holes are produced.

8. The method according to one of the preceding claims, characterized in that, The ablation of the surface tread pattern (8) by means of laser radiation is carried out by sweeping the laser radiation multiple times, wherein the focal position of the laser radiation is preferably changed between the sweeps and / or during each sweep.

9. A forming segment of a segmented vulcanization mold for a vehicle tire, wherein the forming surface of the forming segment shapes the tread pattern of a segment of the tire to be vulcanized, the forming segment is preferably made by means of the method according to any one of the preceding claims, and wherein the forming segment has at least one sub-region, wherein at least one of the sub-regions has a modified surface tread (8), which is obtained by ablating the original model by means of laser radiation, and wherein the surface tread (8) of the original model is modified by ablation by means of laser radiation such that the formed segment has an arithmetic mean height (Sa) greater than 5 μm and less than 100 μm in accordance with ISO 25178.

10. A vehicle tire, preferably made by the method according to one of claims 1 to 8 and / or made of the formed segment according to claim 9, wherein the vehicle tire has at least one sub-region with a vehicle tire surface tread, wherein the vehicle tire surface tread has an arithmetic mean height (Sa) greater than 5 μm and less than 100 μm in accordance with ISO 25178.

11. The vehicle tire according to claim 10, characterized in that the structural dimensions of the vehicle tire surface tread are less than 0.1 mm × 0.1 mm, in particular the Sa of the vehicle tire surface tread is greater than 10 μm, preferably greater than 15 μm and / or less than 80 μm, preferably less than 60 μm.

12. The vehicle tire according to one of claims 10 to 11, characterized in that, the surface roughness Sa, Ssk and / or Sku of the vehicle tire surface tread is designed to be different in the circumferential direction from the shoulder region to the equator line and / or on each tread block.

Images