VULCANISATION MOLD FOR PNEUMATIC VEHICLE TIRES

Description

[0001] The invention relates to a vulcanization mold for pneumatic vehicle tires with molded parts, such as profile ring segments and side shells, which each have an inner side facing the mold cavity and are provided with at least one through-bore for a mold pin, into which a metallic insert is inserted instead of a mold pin in an exchangeable manner and from the inner side and secured against twisting.

[0002] Pneumatic vehicle tires designed and suitable for use in winter driving conditions, especially on icy surfaces, such as so-called Nordic tires, feature numerous narrow cuts in the tread and are often additionally equipped with studs. These studs are subsequently inserted into holes formed in the tread of the fully vulcanized tire during vulcanization. These holes are formed during the tire's vulcanization in a vulcanization mold by mold pins attached to the tread ring segments and protruding from the inside of the tread ring segments.If spike positions (bores) have been created in a vulcanization mold and it subsequently turns out that no mold pins are to be used to create spike holes in the tread, or if previously inserted mold pins are to be removed, the existing holes are closed from the inside of the mold parts with inserts that are largely flush with the inside of the mold. Mold pins are removed, for example, if the stud sequence on the tread results in undesirable noise emissions from the tire on dry surfaces, if too many studs cause unacceptable road wear, or if a specific performance gradation is desired within a product line.The inserts used to date leave circular marks on the tread of the vulcanized tire, which impair the overall appearance of the tire and are therefore perceived as visually disturbing.

[0003] A vulcanization mold of the type mentioned above is known, for example, from DE 10 2018 209 677 A1. This document discloses a method for producing profile ring segments of a tread of a vehicle tire, wherein mold pins for forming stud holes in the tread are introduced into the inner side of the profile ring segments. Recesses are created at the mold pin positions, into which inserts adapted to the recesses are inserted, each of which is provided with a mold pin. In a preferred embodiment, the inserts have at least one elevation on their cover surfaces, each of which imprints an ice reservoir into the tread of the tire. KR 2020 0000013 A discloses a vent valve for inserting a bore of a vulcanization mold, wherein the vent valve has a housing and a movable piston that can close the vent bore during tire molding.This can be provided with a design on its outer side facing the inside of the mold, which imprints a pattern into the outer surface of the tire to complete its tread design. JP 2011 116012 A also discloses a vent valve insertable into a bore in the front part of a vulcanization mold, having a spring-loaded valve closure which is moved into the closed position by the molding tire during molding. The valve closure is provided on the outside with at least one projection or at least one recess. US 2015 / 0251367 A1 discloses an insert insertable into a vulcanization mold and having a mold pin to form holes in the tire to be vulcanized for the later insertion of spikes.Separate, replaceable elements are attached to the insert on the inside of the molded part, which ensure, for example, that the vulcanized tire is visually aligned with the rest of the tread design, for example with incisions formed there.

[0004] The invention is based on the object of designing or constructing inserts inserted into bores of molded parts in such a way that they improve the overall appearance of the vulcanized tire and / or the areas formed by them in the tread can positively influence the stiffness of the tread and thus its performance.

[0005] The object is achieved according to the invention in that the insert has a three-dimensionally structured element projecting beyond the inside of the mold by 0.3 mm to 2.0 mm.

[0006] According to the invention, a three-dimensionally structured element is embossed into the rubber material of the tire at the insert location on the outside. This element can be visually well adapted to the overall appearance of the tire or can even visually emphasize it by highlighting the tire's intended use through its design, for example. The structure of the element can also be designed such that its embossing in the tread of the vulcanized tire locally improves stiffness or snow grip, for example, by promoting the accumulation of snow in the structure formed in the tread, thus improving snow-on-snow friction.Such a structure can, for example, be composed of several micro-webs running parallel to one another with a height and width of, in particular, 0.3 mm to 0.8 mm, which form impressions in the tread with corresponding grooves (formed by the micro-webs) and rubber webs in between.

[0007] According to preferred embodiments, the three-dimensionally structured element of the insert is figurative, designed as at least one character, for example, at least one number or one letter, as a sequence of numbers and / or letters, or as a logo. The element can therefore be designed in such a way that it imprints a structure in the tire that emphasizes the tire's intended use or that represents a trademark or product name.

[0008] For inserting the insert, the vulcanization mold preferably has a stepped bore with three sections, which is in particular an existing stepped bore intended for a mold pin. The insert, with a base portion flush with the inside of the molded part, is inserted into the section of the stepped bore located furthest toward the inside of the mold. A stepped bore allows for detachable fastening of the insert and thus also enables its replacement.

[0009] Furthermore, a particularly preferred embodiment is one in which at least the three-dimensionally structured element of the insert, preferably the entire insert, has been built up or manufactured layer by layer from a metal powder using an additive process. A particularly suitable additive process is, for example, selective laser melting. An insert produced in this way can have a particularly complex three-dimensional element. In a further preferred embodiment, the base part of the insert is a turned part on which the three-dimensionally structured element has been built up layer by layer from a metal powder using an additive process. Alternatively, complex three-dimensionally structured elements can also be formed on inserts produced by a milling process.

[0010] Preferably, the three-dimensionally structured element projects beyond the inside of the mold by 1.0 mm to 2.0 mm and has a diameter of 3.0 mm to 15.0 mm.

[0011] Further features, advantages and details of the invention will now be described in more detail with reference to the schematic drawing, which shows an embodiment. Fig. 1 an embodiment of a conventional stepped bore provided for inserting a mold pin in a profile ring segment of a vulcanization mold for a pneumatic vehicle tire in radial section, Fig. 2 a view of a variant of an insert in an oblique view, Fig. 3 the stepped bore Fig. 1 with inserted insert, which is partly shown in radial section, and Fig. 4 a view of a section of a profile ring segment with inserted insert.

[0012] The term "radial direction" used in the description refers to a tire to be formed and vulcanized in the vulcanization mold. The vulcanization mold is a vulcanization mold for a pneumatic vehicle tire of any design, in particular for passenger cars, vans, light trucks, or commercial vehicles. The exemplary embodiment described below refers to a vulcanization mold with a segmented profile ring with mold pin positions for forming holes in the tread for inserting studs into the tread, and to a vulcanization mold for a pneumatic passenger car tire, preferably a so-called Nordic tire.

[0013] Such a vulcanization mold typically has side shells that form the sidewalls of the tire, and a number, for example 7 to 14, of profile ring segments that form the tread pattern in the rubber material of the tread of a tubular tire and together form the profile ring. For vulcanization, the fully constructed green tire is placed in the vulcanization mold and molded therein in a known manner. Each profile ring segment contains a plurality of stepped bores into which mold pins are inserted and held by screws. During vulcanization of the tire, the mold pins form holes in the tread into which studs can be inserted once the tire is fully vulcanized.

[0014] Fig. 1 shows a radial section through a stepped bore 1 in a small portion of a profile ring segment 2, intended for inserting a mold pin. The inner side of the profile ring segment 2 facing the inside of the mold, the mold cavity, is designated 2a. The stepped bore 1 has three sections that run centrally to one another and are circular in cross-section: a section 1a adjoining the inner side 2a and having a constant diameter d1, a middle section 1b with a constant diameter d2 that is smaller than d1, and a third section 1c, with which the stepped bore 1 opens outwards at the rear of the profile ring segment 2 and which has a constant diameter d3 that is larger than the diameter d2 and, in the example, corresponds to the diameter d1. The diameter d1 in section 1a is adapted to the diameter of the mold pin to be inserted in this section.An inserted mold pin can thus be secured from the rear of the profile ring segment 2 using a screw. A second bore 3, with a diameter significantly smaller than diameter d1, partially overlapping section 1a and extending over its radial extent, allows the insertion of a pin serving as an anti-twist device. The diameter d1 of the first section 1a of the stepped bore 1 is, for example, 4.00 mm to 6.00 mm, and the diameter of bore 3 is in the range of 1.50 mm to 2.00 mm.

[0015] In Fig. 3 Instead of a mold pin, an insert 4 is inserted into the stepped bore 1 at a omitted spike position and fixed with a screw 7.

[0016] In the Fig. 2 and Fig. 3 In the embodiment shown, the insert 4 has a cylindrical base part 5 located in section 1a of the stepped bore 1, with a shoulder 5a that is approximately semicircular in cross-section. This shoulder 5a is designed according to the overlapping bore 3 in section 1a of the stepped bore 1. The insert 4 projects beyond the inner side 2a with a three-dimensionally structured element 6, which in the example is figuratively designed, namely as a schematic snowflake. The element 6 has a constant or varying height of, in particular, 0.3 mm to 2.0 mm, in particular 1.0 mm to 2.0 mm, a diameter of 3.0 mm to 6.0 mm, and in the embodiment shown is composed of six regularly distributed star arms, all of which are designed in a consistent manner. Fig. 3 the base part 5 of the insert 4 is in section, but the element 6 is shown in side view.

[0017] Fig. 4shows a view of a section of the inside of a tread ring segment 2 with shaped ribs 8, which form grooves in the tire tread, and with sipes 9, which form narrow incisions in the tire tread. The shaped ribs 8 encircle a surface element, which forms the outer surface of a tread block in the tire tread and from which a stepped bore 1 extends. The star-shaped element 6, which projects beyond the surface element, can be seen from the insert 4, which is inserted into the stepped bore 1 and secured by a screw from the outside of the tread ring segment 2. An embossed "snow star" as a negative of element 6 is then located at this point in the vulcanized tread.

[0018] The projection 5a of the base part 5 serves, similar to a mold pin, as an anti-rotation device. Alternatively, a separate bolt can be used, in which case the cylindrical base part 5 is provided with a corresponding groove or channel along its radial extension. The part of the insert 4 that protrudes on the inside of the mold, element 6, can be designed with a corresponding overlap of the bolt.

[0019] The illustrated design of element 6 as a snowflake-like element is merely an example. Element 6 can have any pictorial or other design, for example, it can be designed as a logo or part of a logo.

[0020] The insert 4 consists of a metal or a metal alloy and, according to a preferred embodiment, is manufactured together with the element 6 using an additive manufacturing process, for example, selective laser melting, from a metal powder and thus built up layer by layer. Such a process allows for the simple production of elements 6 of any desired design. Alternatively, the base part 5 of the insert 4 is a turned part, i.e., produced by machining, on which the aforementioned groove or channel is introduced, and on whose upper side the element 6 is built up from a metal powder using an additive manufacturing process, for example, selective laser melting. The insert 4 can also be manufactured using a casting process, and the element 6 can be designed by milling or laser engraving. It is also possible to produce complete inserts 4 using a milling process.

[0021] In a further embodiment of the invention, inserts 4 are inserted into holes formed separately in mold segments or side shells of vulcanization molds, in particular stepped holes, and are held in place by screws, allowing replacement. Elements 6 of any design can thus be embossed locally into the rubber material on the outside of the tire, in the tread or in the sidewalls, or to imprint designs or structures that improve the stiffness of the tread and / or its performance. The holes provided for this purpose can have a larger or smaller diameter than conventional stepped holes for mold pins, for example, in the order of up to 15.00 mm. List of reference numbers

[0022] 1Step hole 1a, 1b, 1cSection 2Profile ring segment 2aInside 3Bore 4Insert 5Base part 5aAppendix 6Element 7Screw 8Form web 9Laminate d1, d2, d3Diameter

Claims

1. Vulcanization mould for pneumatic vehicle tyres, having mould parts, such as profile-ring segments (2) and side shells, which respectively have an inner side (2a) towards the mould cavity and are provided with at least one through-bore (1) for a mould pin, into which, instead of a mould pin, a metallic insert (4) is inserted in an exchangeable manner and from the inner side (2a) and so as to be secured against twisting, characterized in that the insert (4) has a three-dimensionally structured element (6) protruding by 0.3 mm to 2.0 mm beyond the mould inner side (2a).

2. Vulcanization mould according to Claim 1, characterized in that the three-dimensionally structured element (6) of the insert (4) is designed as a figure or as at least one character, for example at least one digit or one letter, as a digit and / or letter sequence or as a logo.

3. Vulcanization mould according to Claim 1, characterized in that the bore is a stepped bore (1) with three portions (1a, 1b, 1c), in particular a stepped bore provided for a mould pin, wherein the insert (4) is inserted by way of a base part (5), which terminates flush with the inner side (2a), into that portion (1a) of the stepped bore (1) which is situated furthest on the mould inner side.

4. Vulcanization mould according to one of Claims 1 to 3, characterized in that at least the three-dimensionally structured element (6) of the insert (4) has been constructed in layers from a metal powder in an additive process.

5. Vulcanization mould according to one of Claims 1 to 4, characterized in that the insert (4), complete with the three-dimensionally structured element (6), has been constructed in layers from a metal powder in an additive process.

6. Vulcanization mould according to one of Claims 1 to 4, characterized in that the base part (5) of the insert (4) is a turned part on which the three-dimensionally structured element (6) has been constructed in layers from a metal powder in an additive process.

7. Vulcanization mould according to one of Claims 1 to 4, characterized in that the insert (4), complete with the three-dimensionally structured element (6), has been produced in a milling process.

8. Vulcanization mould according to one of Claims 1 to 7, characterized in that the three-dimensionally structured element (6) protrudes by 1.0 mm to 2.0 mm beyond the mould inner side.

9. Vulcanization mould according to one of Claims 1 to 8, characterized in that the three-dimensionally structured element (6) has a diameter of 3.0 mm to 15.0 mm.