TIRE HEATING MOLD

Description

[0001] The invention relates to a tire heating mold for vulcanizing a pneumatic tire, wherein the pneumatic tire has a tread with sidewalls and a running surface, and wherein the tire heating mold has profile segments for forming radial grooves in the tread and sidewall shapes. The invention further relates to a heating press and a method for vulcanizing a pneumatic tire with a heating press and a pneumatic tire.

[0002] The geometry of pneumatic tire treads influences a multitude of tire properties, particularly grip, rolling resistance, and noise emissions. To better meet these sometimes conflicting requirements, grooves in the tread are known to be either parallel to the tire's axis of rotation or parallel to its circumferential surface. However, the production of these known grooves results in seam zones that extend to the radially outer surface of the tread, thus representing a weak point. Other devices for producing axially parallel grooves are very expensive and prone to failure or require extensive maintenance.

[0003] DE 60 214 915 T2 discloses a tire vulcanization mold that creates radial and axial recesses in the treads of pneumatic tires. The axial recesses are created by protruding components supported by shoulder sectors that move between an open and a closed configuration. The pneumatic tire is inserted into the open configuration of the tire vulcanization mold, whereupon the mold is closed and the protruding components are moved radially into the tire. The tread material flows around the protruding components and then bonds together, forming a seam zone.

[0004] It is further known from DE 60 2005 000 902 T2, which also deals with tire vulcanization forms, that seam zones can represent a weak point, and this publication attempts to overcome this disadvantage by creating an extended seam zone through the geometry of the protruding component.

[0005] Furthermore, US Patent 2007 / 077320 A1 discloses a tire vulcanization method which creates indentations when the tire is formed using bolts, thereby reducing seam zones.

[0006] Against this background, the invention is based on the objective of providing a device of the type mentioned at the outset and a method that overcomes the aforementioned disadvantages by providing a cost-effective, reliable and low-maintenance tire heating mold for forming indentations in side surfaces that run essentially parallel to the tread, wherein the tire heating mold does not produce a seam zone that extends to the radially outer surface of the tread, and preferably no seam zone is produced.

[0007] This problem is solved by a tire heating mold according to the features of claim 1, as well as a heating press and a method for vulcanizing a pneumatic tire with a heating press and a pneumatic tire according to the dependent claims. The subclaims relate to particularly advantageous embodiments of the invention.

[0008] According to the invention, a tire heating mold for vulcanizing a pneumatic tire is provided, wherein the pneumatic tire has a tread with sidewalls and a running surface, and wherein the tire heating mold has profile segments for forming radial depressions in the tread and sidewall shapes. At least on one sidewall shape on a surface forming the pneumatic tire, a bolt is formed which projects from the at least one sidewall shape for forming depressions in the sidewall that run substantially parallel to the running surface when the pneumatic tire is inserted into the tire heating mold. A cross-section of the bolt has an elliptical, a triangular, or a teardrop-shaped geometry.

[0009] For the purposes of this invention, radial depressions in the tread are understood to be depressions that are formed in the radial direction of the pneumatic tire and, for example, form circumferential grooves. Depressions extending substantially parallel to the tread surface are understood to be depressions whose main axis of extension runs parallel to the tread surface, wherein the distance of the depression to the tread surface is approximately the same at every position of the depression.

[0010] A tire heating mold with a sidewall shape according to the invention makes it possible to create recesses in the sidewalls of pneumatic tires, whereby seam zones in the tread, which are created by the flow around a bolt, are reduced or avoided, whereby at least seam zones in the area of ​​the radially outer surface of the tread are avoided.

[0011] A preferred embodiment provides that the bolt can be inserted into the sidewall mold, preferably manually, with the bolt and the sidewall mold each having a contact surface for mechanical contact. An insertable bolt allows for the simple removal of the pneumatic tire from the sidewall after the vulcanization process, along with the bolt, and the subsequent removal of the bolt itself. This simplifies the demolding of the pneumatic tire from the sidewall. A manually insertable bolt has proven to be particularly easy to implement.

[0012] Another preferred embodiment provides that the bolt is permanently attached to the sidewall mold, preferably in a movable, and in particular passively movable, manner. A permanently attached bolt to the sidewall eliminates the need to insert the bolt into the sidewall. Simple demolding of the pneumatic tire from the sidewall, which is particularly relevant for bolts that protrude significantly from the sidewall, is made possible by moving the bolts out of the pneumatic tire during or before demolding the pneumatic tire from the sidewall. A particularly simple implementation is possible with a passive movement of the bolts, so that the bolts do not require an actuator but are moved along with the tire heating mold by a process.

[0013] Another preferred embodiment provides that the bolt is made of a high-strength material, in particular an iron alloy or an aluminum alloy. High-strength materials have proven to be particularly suitable because they can withstand the demolding forces, especially when the bolts protrude far from the side wall shape.

[0014] Another preferred embodiment provides that the bolt has, at least in certain areas, an adhesion-reducing and / or friction-reducing coating, in particular a polytetrafluoroethylene coating. It has been shown that an adhesion-reducing or friction-reducing coating reduces the demolding forces acting on the bolt. In particular, a polytetrafluoroethylene coating has proven to be resistant to the prevailing temperatures and forces, effectively reducing the demolding forces.

[0015] Another preferred embodiment provides that the length of the bolt, i.e., the distance by which the bolt projects from the sidewall mold, is more than 10%, preferably more than 20%, further preferably more than 40%, and most preferably more than 80% of the height of the tire heating mold. The height of the tire heating mold corresponds to the width of the tread of the pneumatic tire to be manufactured. A longer bolt makes it possible to provide indentations in the pneumatic tire both centrally and beyond the center.

[0016] Another preferred embodiment provides that a central axis of the bolt preferably has a circumferential extension component. Such an orientation of the bolt makes it possible to create recesses that also have a circumferential orientation.

[0017] The invention provides that a cross-section of the bolt has an elliptical, triangular, or teardrop-shaped geometry. These cross-sectional geometries have proven particularly suitable both in the manufacturing process of the pneumatic tire and in their resulting depression within the tire.

[0018] Another preferred embodiment provides that the bolt has an arcuate geometry and / or a conical geometry along its main axis of extension. An arcuate geometry has proven suitable for creating a particularly constant distance between the recess and the running surface. A conical geometry has proven advantageous for reducing demolding forces.

[0019] According to the invention, a heating press is provided comprising a heating press upper part and a heating press lower part as well as a container, wherein the container has a tire heating mold according to the invention.

[0020] A heating press with a sidewall shape according to the invention makes it possible to create recesses in the side surfaces of pneumatic tires, whereby seam zones in the tread, which are created by the flow around a bolt, are reduced or avoided, whereby at least seam zones in the area of ​​the radially outer surface of the tread are avoided.

[0021] According to the invention, a method for vulcanizing an air tire with a heating press, in particular a heating press according to the invention, is provided, comprising the following steps: a) Loading the open heating press by inserting a pneumatic tire to be vulcanized, whereby the movement of the pneumatic tire causes a portion of a bolt to penetrate a tread of the pneumatic tire, b) Conforming the pneumatic tire and bringing together profile segments in the radial direction of the pneumatic tire, c) Vulcanizing the pneumatic tire, d) Opening the heating press, unloading the pneumatic tire and removing the bolt.

[0022] The method according to the invention makes it possible to produce pneumatic tires with recesses in the sidewalls, whereby seam zones in the tread that are created by the flow around a bolt are reduced or avoided, whereby at least seam zones in the area of ​​the radially outer surface of the tread are avoided.

[0023] According to the invention, a pneumatic tire is provided with a tread having sidewalls and a running surface, wherein the sidewalls have recesses extending at a predominantly constant distance from the running surface, manufactured using a method according to the invention. The pneumatic tire according to the invention has recesses in the sidewall, whereby seam zones are avoided.

[0024] The invention allows for numerous embodiments. To further illustrate its basic principle, one of these is shown in the drawing and described below. This shows in Fig. 1 a section of a side wall shape with bolts in a cross-section.

[0025] Figure 1Figure 1 shows a cross-section of a section of a sidewall mold 1 with bolts 2 of a tire heating mold for vulcanizing a pneumatic tire. The sidewall mold 1 has a surface 3 that forms the pneumatic tire and imprints the sidewall geometry onto the tire during the vulcanization process.

[0026] Bolts 2 project from surface 3 and are fixed to the sidewall shape 1. The bolts 2 extend predominantly in the axial direction A of the pneumatic tire being manufactured. However, the bolts 2 also extend radially in direction R, creating indentations in the pneumatic tire that run parallel to the tread. Furthermore, the bolts 2 have a radius of curvature corresponding to the radius of curvature of the tread of the unvulcanized pneumatic tire in the axial direction. The bolts 2 also extend circumferentially in direction U to create indentations that do not run exactly in the axial direction of the pneumatic tire.

[0027] The sidewall shape 1 also has a support surface 4 on which it is placed in the tire heating mold. The sidewall shape 1 has contact areas 5 with which it comes into contact with the tread segments during the vulcanization process. Reference symbol list

[0028] 1. Sidewall shape 2. Bolts 3. Surface 4. Bearing surface 5. Contact areas Aaxial direction R radial direction U circumferential direction

Claims

1. Tyre heating mould for vulcanizing a pneumatic tyre, wherein the pneumatic tyre has a tread with lateral surfaces and a tread surface, wherein the tyre heating mould has profile segments for embossing radial depressions in the tread and side wall moulds (1), wherein a stud (2), which protrudes from the at least one side wall mould (1), for embossing depressions in the lateral surface running substantially parallel to the tread surface when inserting the pneumatic tyre into the tyre heating mould is formed on at least one side wall mould (1) on a surface forming the pneumatic tyre, characterized in that a cross section of the stud (2) has an elliptic, a triangular or a teardrop-shaped geometry.

2. Tyre heating mould according to Claim 1, characterized in that the stud (2) is insertable, preferably manually, into the side wall mould (1), wherein the stud (2) and the side wall mould (1) each have a contact surface for mechanically contacting one another.

3. Tyre heating mould according to Claims 1 and 2, characterized in that the stud (2) is permanently mounted preferably so as to be displaceable, in particular passively displaceable, on the side wall mould (1).

4. Tyre heating mould according to one of the preceding claims, characterized in that the stud (2) comprises a high-strength material, in particular an iron alloy or an aluminium alloy.

5. Tyre heating mould according to one of the preceding claims, characterized in that the stud (2) has an adhesion-reducing and / or friction-reducing coating, in particular a polytetrafluoroethylene coating, at least in sub-regions.

6. Tyre heating mould according to one of the preceding claims, characterized in that the length of the stud (2) is more than 10%, preferably more than 20%, more preferably more than 40% and most preferably more than 80% of the height of the tyre heating mould.

7. Tyre heating mould according to one of the preceding claims, characterized in that a central axis of the stud (2) preferably has a component of extent in the circumferential direction U.

8. Tyre heating mould according to one of the preceding claims, characterized in that the stud (2) along its main axis of extent has an arcuate geometry and / or a conical geometry.

9. Heating press comprising a heating press upper part and a heating press lower part and a container, characterized in that the container has a tyre heating mould according to one of the preceding claims.

10. Method for vulcanizing a pneumatic tyre with a heating press according to Claim 9, comprising the following steps: a) loading the open heating press by inserting a pneumatic tyre to be vulcanized, wherein a sub-region of a stud (2) penetrates a tread of the pneumatic tyre due to the movement of the pneumatic tyre; b) conforming the pneumatic tyre and converging profile segments in the radial direction R of the pneumatic tyre, c) vulcanizing the pneumatic tyre, d) opening the heating press, unloading the pneumatic tyre and removing the stud (2).

11. Pneumatic tyre with a tread having lateral surfaces and a tread surface, wherein the lateral surfaces have depression which runs at a largely constant spacing from the face of the tread surface, produced by a method according to Claim 10.