Method for producing a profile segment

Abstract

The invention relates to a method for producing a profile segment of a segmented vulcanizing mold for vehicle tires, wherein the molding surface of the profile segment forms a segment of the tread pattern of a tire to be vulcanized, comprising the following step: a) producing a profile segment, wherein the profile segment has a surface profile to be changed at least in a partial area, wherein the surface profile (8) is produced in this way by means of laser radiation.

Description

The invention relates to a method for producing a profile segment of a segmented vulcanization mold for vehicle tires, wherein the molding surface of the profile segment molds a segment of the tread profile of a tire to be vulcanized, comprising the steps of producing a profile segment and changing the surface profile of a partial region of the profile segment.The invention further relates to a profile segment with changes in the surface profile of a subregion of the profile segment, and to a vehicle tire.Vulcanization molds for tires include molded parts which together form the radially outer surface of the tire such as the tread, shoulder region, sidewalls and bead region. The segments which form the tread are called tread segments.The term "positive profile" comprises all the sipes of the profile and possible further sipes such as those for the insertion of laminated sheets for passenger cars and van tyres.The unvulcanized green tire blank is vulcanized in the vulcanization mold and is converted into its final rubber-elastic state by rubber crosslinking reactions. The tire receives its profile configuration by the corresponding negative configuration of the mold surfaces of the mold segments.By forming surfaces is meant those surfaces of the forming segments which give the green tyre its corresponding configuration.For tire performance, in particular for the snow and ice performance of winter tires, it is advantageous if the shell-shaped surface of the tire tread, the vehicle tire surface profile of the vehicle tire, has a defined roughnessIt is known from EP 3 261 830 B1 that fine structures which are applied to a model segment by means of plasma coating are advantageous for the adhesion of a vehicle tire produced therewith under winter conditions.It is therefore the object of the invention to provide a cost-effective and adaptable method for producing a profile segment, and a profile segment, of a segmented vulcanizing mold for vehicle tires, with which the shell-shaped tread surface of a tire to be vulcanized is to be provided with a defined roughness or a defined surface profile. It is a further object of the invention to provide a vehicle tire having such a vehicle tire surface profile.This object is achieved by a method according to the features of patent claim 1 and a profile segment and a vehicle tire according to the subordinate claims. The dependent claims relate to particularly expedient developments of the invention.According to the invention, a method for producing a profile segment of a segmented vulcanizing mold for vehicle tires is therefore provided, wherein the molding surface of the profile segment molds a segment of the tread profile of a tire to be vulcanized, having the following step: a) producing a profile segment, wherein the profile segment has a surface profile (8) to be produced by means of laser radiation at least in a partial region, wherein the surface profile is produced by means of laser radiation in such a way that the surface profile has an average arithmetic height (Sa) of greater than 5 μm and less than 1000 μm according to ISO 25178 and or embossing plates having a material thickness of 0.1 mm to 0.5 mm and a height of 0.1 mm to 2 mm.A partial region of the surface profile is understood to mean both a region of exactly one profile block and a region of each profile block. The partial region can also extend over the entire surface profile, wherein surface profile is understood to mean the region of a profile segment which forms the vehicle tire surface profile of the vehicle tire.Embossing plates are understood to mean elements which protrude from the further profile segment and serve for forming fine cuts in vehicle tires.It has been found that changing the surface profile of profile segments by means of laser radiation to a specific roughness enables vehicle tires which solve the conflict of goals between dry adhesion and snow or ice adhesion at a higher level. This is attributed to the fact that, in the case of a large contact surface between the vehicle tire and the underlying surface, which is relevant in particular for dry adhesion, a sufficient negative fraction is also provided, which can be arranged in such a way that high adhesion is achieved in the case of snow or ice adhesion. It has been found here that such roughnesses in profile segments can be produced by means of laser radiation in a particularly simple and cost-effective manner.A preferred embodiment provides that in step a) the profile segment is produced by means of the following steps:a1) creating a rigid model segment having a shell-shaped tread surface,a2) milling the positive profile of the tread into the shell-shaped tread surface of the model segment to obtain a master model,a3) creating a flexible impression of preferably silicone rubber from the master model, wherein preferably for shaping the silicone rubber lamellae are impressed into the silicone rubber,a4) creating a rigid casting of preferably gypsum from the casting of preferably silicone rubber to form a core segment,a5) casting all annularly juxtaposed core segments preferably with an aluminum-magnesium alloy to obtain a vulcanization mold, which is subsequently divided into individual profile segments. These method steps make possible a particularly cost-effective and process-safe production of profile segments.A further preferred embodiment provides that the profile segment is milled from full in step a) or is produced by means of generative laser-based methods. This makes possible an increase in efficiency, since molding steps can be dispensed with. Generative laser-based methods for producing profile segments, in particular laboratory profile specimens, have proven advantageous.A further preferred embodiment provides that, by changing a surface of the subregion, the surface profile is produced by means of a generative method, in particular by means of selective laser melting and or laser deposition welding and or or laser sintering and or laser soldering. Generative methods have proven advantageous since a plurality of structures and surface roughnesses can be produced in different ways in a simple manner. Furthermore, the applied material may have suitable properties, such as chemical and mechanical resistance, which are superior to a profile segment material manufactured cost-effectively.A further preferred embodiment provides that the surface profile is generated by a change of a surface of the subregion by means of an abrasive method, in particular laser cutting or laser drilling. A removal method carried out by means of laser radiation makes it possible in a particularly simple manner to produce a multiplicity of structures and surface roughnesses in different ways, wherein preferably only partial surfaces of each profile element are machined.A further preferred embodiment provides that a structure size of less than 0.1 mm×0.1 mm, in particular a surface profile Sa of greater than 10 μm, preferably of greater than 15 μm, and or of less than 80 μm, preferably of less than 60 μm, is produced. It has been found that small structure sizes, in particular surface profiles Sa of greater than 10 μm and less than 80 μm, lead to particularly good values with regard to snow or ice adhesion with particularly good dry adhesion.A further preferred embodiment provides that an Ssk value according to ISO 25178 of greater than -50, preferably greater than -20, further preferably greater than -10, further preferably greater than -3 and / or less than 50, preferably less than 30, further preferably less than 20 and preferably an Ssk value according to ISO 25178 of ≤2 is generated. It has been found that the preferred Ssk values for particularly good dry adhesion lead to particularly good values with regard to snow or ice adhesion.A further preferred embodiment provides that an Sz value according to ISO 25178 of greater than 0.5 mm and / or of less than 2 mm is generated. It has been found that the preferred Sz values lead to particularly good values with regard to snow or ice adhesion in the case of particularly good dry adhesion. It has furthermore been found that a combination of the said Sz values with the aforementioned Ssk values and Sku values leads to a further improved adhesion.A further preferred embodiment provides that the surface roughnesses Sa, Ssk, Sz and or Sku are formed differently from the shoulder zone toward the equator and or on a respective profile block in the circumferential direction. A different configuration of the surface roughnesses of the equator, i.e. of the tread surface arranged centrally between the shoulder regions, and of the shoulder zones makes it possible to produce a surface roughness in the different lateral regions of the tread, which surface roughness is particularly suitable for their predominant functions, i.e. for example for adhesion to ice or for adhesion in wet or dry brakes. Particularly effective adhesion in the circumferential direction and in the lateral direction is made possible. The predominant functions of a profile block, which are variable over the circumferential direction, can thus also be optimized.A further preferred embodiment provides that the surface roughnesses Sa, Ssk, Sz and or Sku are generated in the form of a defined pattern, preferably by means of dot matrix or vectorial hatching. It has been found that an arrangement of the surface roughnesses both in the form of a dot matrix and a vectorial hatching, in particular by means of a dot matrix or vectorial hatching, can be advantageous with regard to a solution of the mentioned conflict of goals at a higher level.According to the invention, a profile segment of a segmented vulcanization mold for vehicle tires is provided, wherein the mold surface of the profile segment molds a segment of the tread profile of a tire to be vulcanized, preferably produced by means of a method according to the invention, wherein the profile segment has at least one partial region, wherein the at least one partial region has a surface profile modified by means of laser radiation, wherein the modified surface profile has an average arithmetic height (Sa) of greater than 5 μm and less than 1000 μm according to ISO 25178 and or embossing plates with a material thickness of 0.1 mm to 0.5 mm and a height of 0.1 mm to 2 mm.It has been found that a surface profile of profile segments with a roughness with an average arithmetic height (Sa) of greater than 5 μm and less than 1000 μm and or with embossed sheets which was produced by means of laser radiation enables vehicle tires which solve the conflict of goals between dry adhesion and snow or ice adhesion at a higher level.For the adhesion of vehicle tires produced with such profile segments, it has proven advantageous if the surface roughness was carried out by means of generative methods or by means of an ablating method, in each case by means of laser radiation.According to the invention, a vehicle tire, preferably produced by a method according to the invention and or by a profile segment according to the invention, is provided, wherein the vehicle tire has at least one partial region with a vehicle tire surface profile, wherein the vehicle tire surface profile has an average arithmetic height (Sa) of greater than 5 μm and less than 1000 μm according to ISO 25178 and or sipes with an extent of 0.1 mm to 0.5 mm and a height of 0.1 mm to 2 mm.It has been found that a vehicle tire having a roughness with an average arithmetic height (Sa) of greater than 5 μm and less than 1000 μm and or fine incisions with an extent of 0.1 mm to 0.5 mm and a height of 0.1 mm to 2 mm can solve the conflict of goals between dry adhesion and snow or ice adhesion at a higher level.A preferred embodiment provides that the vehicle tire surface profile has a structure size of less than 0.1 mm×0.1 mm, in particular a vehicle tire surface profile Sa of greater than 10 μm, preferably of greater than 15 μm, and or of less than 80 μm, preferably of less than 60 μm. It has been found that small structural sizes, in particular vehicle tire surface profile Sa of greater than 10 μm and less than 80 μm, lead to particularly good values with regard to snow or ice adhesion with particularly good dry adhesion.A further preferred embodiment provides that surface roughnesses Sa, Ssk, Sk and or Sku of the vehicle tire surface profile from the shoulder zone toward the equator and or on a profile block in each case are formed differently in the circumferential direction. A different formation of the surface roughnesses of the equator, i.e. of the tread surface arranged centrally between the shoulder regions, and of the shoulder zones makes it possible to produce a surface roughness in the different lateral regions of the tread which is particularly suitable for their predominant functions. Particularly effective adhesion in the circumferential direction and in the lateral direction is made possible. The predominant functions of a profile block, which are variable over the circumferential direction, can thus also be optimized. FIG. 1 shows a peripheral section of a vehicle tire for passenger cars according to the invention in a sectional illustration with a sectional plane which contains the tire axis, shown in perspective view, FIG. 2 shows cross sections of surface profiles.FIG. 1 shows a tubeless vehicle tire of the radial type of a car with a profiled tread 1 extending from shoulder to shoulder. The profiled tread 1 and the tire sidewalls 2 are each formed extending in the circumferential direction U of the vehicle tire over the entire circumference of the vehicle tire. The tire sidewall 2 is formed at its radially inner end with a bead portion 4 for seating on the rim, respectively. In the bead region 4, a respective best bead core 5 is formed which extends over the entire circumference of the vehicle tire and is formed concentrically with respect to the tire axis. In a known manner, starting from one bead core 5 extends outwards in the radial direction R through the tyre sidewall 2 as far as the profiled tread 1, then in axial extension through the area of extension of the profiled tread 1 as far as the other tyre shoulder and from there, inwards in the radial direction R, through the second tyre sidewall 2 as far as the bead core 5 formed in the second bead area 4, a carcass 3 of radial design extends. The carcass 3 is formed in a known manner from one or more plies of carcass cords embedded in rubber. Radially outside the carcass 3 between the carcass 3 and the profiled tread 1 there is formed in a known manner a belt 6 of a plurality of belt plies of known type which extends over the entire circumference of the vehicle tyre and extends in the axial direction A from tyre shoulder to tyre shoulder. The belt plies are formed from reinforcing elements embedded in rubber-for example steel cords or other reinforcing elements known as suitable for the belt.On the inside of the carcass 3 directed toward the inside of the tire, a tire inner layer 7 formed from particularly airtight rubber material extends in a known manner starting from one bead region 4 along the tire sidewall 2 radially outwards as far as the tire shoulder, then in axial extension from this first tire shoulder to the second tire shoulder and from there in radial direction inwards along the second tire sidewall 2 as far as the second bead region 4.FIG. 2 shows cross sections of surface profiles 8 of profile segments which have a height difference from the highest points 9 to the lowest points 10 of 20 μm to 30 μm. As illustrated, the surface profiles 8 can have a rectangular or triangular geometry and combinations of these basic geometries. Furthermore, round geometries and or rounded corners and edges can also be realized, which exhibit particularly high adhesion, in particular on wet and dry asphalt, with low abrasion. The widths to depth ratios and the distances of the individual depressions can vary here.References 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 3 261 830 B1

[0008]

Claims

Method for producing a profile segment of a segmented vulcanization mold for vehicle tyres, wherein the mold surface of the profile segment molds a segment of the tread profile of a tyre to be vulcanized, having the following step: a) producing a profile segment, wherein the profile segment has a surface profile (8) to be produced by means of laser radiation at least in a partial region, wherein the surface profile (8) is produced by means of laser radiation in such a way that the surface profile (8) has an average arithmetic height (Sa) of greater than 5 μm and less than 1000 μm according to ISO 25178 and / or embossing plates having a material thickness of 0.1 mm to 0.5 mm and a height of 0.1 mm to 2 mm.Method according to claim 1, characterised in that in step a) the profile segment is produced by means of the following steps: a1) creating a rigid model segment which has a shell-shaped tread surface, a2) milling the positive profile of the tread (1) into the shell-shaped tread surface of the model segment to obtain a master model, a3) creating a flexible impression of preferably silicone rubber from the master model, a4) creating a rigid casting of preferably gypsum from the impression of preferably silicone rubber to form a casting core segment, a5) casting all annularly placed casting core segments preferably with an aluminium-magnesium alloy to obtain a vulcanization mould, which is subsequently divided into individual profile segments.Method according to Claim 1, characterized in that the profile segment is milled from full in step a) or is produced by means of generative laser-based methods.Method according to one of the preceding claims, characterized in that a change in a surface of the subregion produces the surface profile (8) by means of a generative method, in particular by means of selective laser melting and / or laser application welding and / or laser sintering and / or laser soldering.Method according to one of Claims 1 to 3, characterized in that the surface profile (8) is produced by changing a surface of the subregion by means of an abrasive method, in particular laser cutting or laser drilling.Method according to one of the preceding claims, characterized in that a structure size of less than 0.1 mm×0.1 mm, in particular a surface profile (8) Sa of greater than 10 μm, preferably of greater than 15 μm, and / or of less than 80 μm, preferably of less than 60 μm, is produced.Method according to one of the preceding claims, characterized in that an Ssk value according to ISO 25178 of greater than -50, preferably of greater than -20, more preferably of greater than -10, more preferably of greater than -3 and / or of less than 50, preferably of less than 30, more preferably of less than 20 and preferably an Sku value according to ISO 25178 of ≤ 2 is generated.Method according to one of the preceding claims, characterized in that an Sz value according to ISO 25178 of greater than 0.5 mm and / or of less than 2 mm is generated.Method according to one of the preceding claims, characterized in that the surface roughnesses Sa, Ssk, Sz and / or Sku are formed differently from the shoulder zone towards the equator and / or on a respective profile block in the circumferential direction.Method according to one of the preceding claims, characterized in that the surface roughnesses Sa, Ssk, Sz and / or Sku are generated in the form of a defined pattern, preferably by means of a dot matrix or vectorial hatching.Profile segment of a segmented vulcanization mold for vehicle tires, wherein the mold surface of the profile segment molds a segment of the tread profile of a tire to be vulcanized, preferably produced by means of a method according to one of the preceding claims, wherein the profile segment has at least one partial region, wherein the at least one partial region has a surface profile (8) modified by means of laser radiation, wherein the modified surface profile (8) has an average arithmetic height (Sa) of greater than 5 μm and less than 1000 μm according to ISO 25178 and / or embossing plates having a material thickness of 0.1 mm to 0.5 mm and a height of 0.1 mm to 2 mm.Vehicle tyre, preferably produced by a method according to one of Claims 1 to 10 and / or produced by a profile segment according to Claim 11, wherein the vehicle tyre has at least one subarea with a surface profile (8), wherein the surface profile (8) has an average arithmetic height (Sa) of greater than 5 μm and less than 1000 μm according to ISO 25178 and / or sipes with an extent of 0.1 mm to 0.5 mm and a height of 0.1 mm to 2 mm.Vehicle tyre according to Claim 12, characterized in that the surface profile (8) has a structure size of less than 0.1 mm×0.1 mm, in particular a surface profile (8) Sa of greater than 10 μm, preferably of greater than 15 μm, and / or of less than 80 μm, preferably of less than 60 μm.Vehicle tyre according to one of Claims 12 to 13, characterized in that the surface roughnesses Sa, Ssk, Sk and / or Sku of the surface profile (8) from the shoulder zone to the equator and / or on in each case one profile block are of different design in the circumferential direction.

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