Pre-cured tread strip for cold retreading a commercial vehicle tire and cold retreaded commercial vehicle tire

Abstract

Pre-cured tread strip (1) for cold retreading a commercial vehicle tire, wherein the tread strip (1) has an outer side (1a) and a back side (1b), and wherein the outer side (1a) is provided with a tread pattern having tread positives and circumferential grooves (2) extending to a tread depth, the deepest points of the circumferential grooves defining a circumferential groove plane (2a) running parallel to the outer side (1a). A groove structure made up of grooves (3) is formed on the back side (1b) of the tread strip (1), the deepest points of the grooves each having a distance (a2), measured perpendicularly to the back side (1b), from the circumferential groove plane (2a).

Description

[0001] 202402852

[0002] Description

[0003] Pre-vulcanized tread for cold retreading of a commercial vehicle tire and cold retreaded commercial vehicle tires

[0004] The invention relates to a pre-vulcanized tread for cold retreading a commercial vehicle tire, wherein the tread has an outer and a rear side, and wherein the outer side is provided with a profile featuring raised ribs and circumferential grooves extending to the tread depth, the deepest points of which define a circumferential groove level running parallel to the outer side. The invention further relates to a cold-retreaded commercial vehicle tire.

[0005] The retreading of commercial vehicle tires, and especially cold retreading, remains widespread. In cold retreading, single-layer vulcanized or pre-vulcanized treads are bonded to tire carcasses from which the worn treads have been removed. The bond between the tire carcass and the vulcanized tread is achieved via a bonding layer of rubber compound, known as the binder layer. This rubber compound is extruded onto the roughened or worn and prepared tire carcass. The tread is then applied, and the tire is placed in an autoclave, where the binder layer is vulcanized, creating a bond between the tread and the tire carcass.After the profiled tread is vulcanized, its back side is roughened, for example using rotating brushes. A bonding agent is then applied to the back side, and the tread is delivered to the end customer, the retreader.

[0006] WO 2019 / 011493 A1 describes such a process for the cold retreading of a commercial vehicle tire and also addresses, in 202402852, a process for roughening the back side of the vulcanized tread. According to this process, the tread is additionally supported on its outer side at the base of the grooves belonging to the tread pattern during roughening. The roughened back side is intended to ensure a good bond between the tread and the bonding rubber layer. Particularly when retreaded commercial vehicle tires are subjected to higher lateral loads, especially depending on the vehicle, there is a possibility or risk that cracks will develop in the retreaded tread. These cracks can propagate under further loads, or even lead to partial detachment of the tread.

[0007] The invention is therefore based on the objective of designing a tread intended for cold retreading in such a way that the formation of cracks in the tread and / or partial detachment of the tread on the retreaded commercial vehicle tire is effectively prevented.

[0008] The problem set out in the invention is solved by forming a groove structure on the back of the tread strip, the deepest points of which are spaced apart from the circumferential groove level, measured perpendicular to the back.

[0009] According to the invention, the grooved structure significantly increases the surface area available for bonding with the rubber compound layer of the binder rubber and causes the rubber compound of the binder rubber to penetrate into the grooves, thereby preventing the risk of detachment or the formation of tears when lateral forces act on the retreaded tire.

[0010] To prevent the groove structure from influencing the stability of the tread, it is advantageous if the distance between the deepest points of the grooves and the circumferential groove level is at least 2.00 mm, and in particular at least 3.00 mm. 202402852

[0011] In further designs, the groove structure covers the back of the tread, in particular completely, or is formed in areas or sections of the back of the tread. These measures allow the design of the tread profile to be taken into account.

[0012] In particular, it is advantageous if the groove structure is formed by omitting areas below the circumferential grooves, a measure that ensures high stability of the vulcanized tread provided to the retreader.

[0013] Various groove designs allow for a positive influence on the adhesion between the groove structure and the penetrating binding rubber, for example, designs of the groove structure with a rectangular, a V-shaped, a U-shaped or an arc-shaped cross-section.

[0014] Particularly advantageous in this regard are closely spaced grooves, especially grooves that have a mutual distance of 0.50 mm to 5.00 mm on the back side of the tread.

[0015] According to another preferred embodiment, the groove structure is a corrugated structure consisting of ribs and grooves with rounded cross-sections.

[0016] A particularly durable bond between the binding rubber and the running strip can be achieved with a design in which the grooves of the groove structure have a cross-section that widens at least partially in the direction of their groove base.

[0017] Further embodiments of the groove structure take into account the thickness and width of the respective tread, such as designs of the grooves of the groove structure with a depth of 1.00 mm to 10.00 mm relative to the back of the tread and / or with an opening width of 1.00 mm to 20.00 mm determined on the back of the tread 202402852, in particular up to 10.00 mm.

[0018] The orientation of the grooves in the grooved structure can also promote a particularly good bond with the binding rubber in certain tread profile designs. It is especially advantageous if the grooves, when viewed from above, are straight, curved, zigzag, or wavy, and particularly parallel to each other. Furthermore, it can be advantageous if the grooves in the grooved structure run circumferentially, transversely, or obliquely to the circumferential direction of the tread.

[0019] In a further advantageous embodiment in this respect, the groove structure has surface areas or sections with different orientations and / or designs of the grooves.

[0020] The invention further relates to a commercial vehicle tire which is cold retreaded with a tread according to one or more of claims 1 to 14 and thus has a tread connected to the tire carcass in a particularly durable manner via the binding rubber.

[0021] Further features, advantages, and details of the invention will now be described in more detail with reference to the schematic drawing, which illustrates exemplary embodiments.

[0022] Fig. 1 shows a cross-section of an embodiment of a vulcanized or pre-vulcanized tread of a vehicle tire,

[0023] Fig. 2 shows another embodiment of such a tread and

[0024] Figures 3 to 6 show different cross-sectional designs of grooves forming a groove structure on the back side of the tread. 202402852

[0025] The tread 1 shown in Figures 1 and 2 is intended for the cold retreading of commercial vehicle tires, for example, tires for trucks or buses. The tread 1 is, in particular, a flat tread with a profiled outer surface 1a and a back surface 1b and is produced in vulcanizing presses, each equipped with a number of heated molds. During the pressing and vulcanizing process, a profile is introduced into a previously produced strip of raw rubber. Four circumferential grooves 2 and profile ribs 4 are shown as examples of the profile on the outer surface 1a. The circumferential grooves 2 have the maximum tread depth (corresponding to that specified for the respective tire) and, for example, in the retreaded tire, are circumferential grooves running straight around the circumference, or alternatively, circumferential grooves with a zigzag or wave-like pattern around the circumference of the tread 1.The deepest points of the circumferential grooves 2 are located on a circumferential groove level 2a running parallel to the outer surface 1a, which is shown as a straight line in Figures 1 and 2. Further profiling of the tread 1 is not shown.

[0026] The reverse side 1b of the tread 1 is provided with a grooved structure consisting of a plurality of grooves 3. In the embodiment shown in Fig. 1, the grooved structure extends over the entire reverse side 1b of the tread 1, covering the entire reverse side 1b. In the embodiment shown in Fig. 2, the grooved structure is located below the profile ribs 4 formed between the circumferential grooves 2. The areas below the circumferential grooves 2 are recessed, at least over those areas of the width of the outer surface 1a occupied by the circumferential grooves 2 in the case of zigzag or wave-shaped circumferential grooves 2. In the embodiment shown in Fig. 2, the grooved structure therefore has five structural sections.

[0027] Preferably, the grooved structure extends over the entire back surface 1b of the tread 1, in particular consisting of straight and parallel grooves 3, which, for example, run in the circumferential direction of the tread. In an alternative embodiment, the grooves 3 on the back surface 1b run in any zigzag or wave shape, in a further alternative embodiment transversely or obliquely across the width of the tread, in any sections or areas (preferably excluding the areas below the circumferential grooves 2) or completely covering the back surface 1b.

[0028] Figures 3 to 6 show different embodiments of the cross-sections of grooves 3 in an enlarged view compared to Figures 1 and 2. Figure 3 shows a groove 3 according to Figures 1 and 2 with a rectangular cross-section. Alternatively, the grooves 3 have a V-shaped cross-section, optionally with different inclinations of their groove walls relative to the back surface 1b. In the embodiment shown in Figure 4, the groove 3 has a rounded U-shaped cross-section, and in the embodiment shown in Figure 5, a rounded semicircular cross-section. In the embodiment shown in Fig. 6, the groove structure is a corrugated structure consisting of rounded grooves 3 separated from each other in cross-section by rounded ribs 3a. In the embodiments shown in Figs. 3 to 5, the grooves 3 of the respective groove structure each have a mutual spacing ai (Fig. 1 and Fig. 2), which is in particular from 0.50 mm to 5.00 mm.Within a groove structure or sections of the groove structure, this spacing can also vary. Furthermore, the grooves 3 have an opening width b of 1.00 mm to 20.00 mm, in particular up to 10.00 mm, determined perpendicular to their extent on the back side 1b.

[0029] In all embodiments, the grooves 3 have a depth t relative to the back surface 1b, which is in particular on the order of 1.00 mm to 10.00 mm, depending on the thickness of the tread 1. In any case, the deepest points of the grooves 3 are located at a distance a2 (Fig. 1, Fig. 2) perpendicular to the outer surface 1a of at least 2.00 mm, in particular at least 3.00 mm.

[0030] The groove structure is imprinted on the back side 1b of the tread 1 during the vulcanization of the tread 1 in the vulcanizing press. The 202402852 pre-vulcanized treads 1, cut according to the circumference of the commercial vehicle tire to be retreaded, are pressed on the back side 1b with a

[0031] They were fitted with bonding agents and then delivered to the retreader.

[0032] 202402852

[0033] Reference symbol list

[0034] 1 tread

[0035] 1a Outside

[0036] 1 b reverse

[0037] 2 circumferential grooves

[0038] 3rd groove

[0039] 3a rib

[0040] 4 Profile rib ai , a2 Spacing b Opening width t > . Depth

Claims

202402852 Patent claims 1. Pre-vulcanized tread (1) for cold retreading a commercial vehicle tire, wherein the tread (1) has an outer side (1a) and a rear side (1b) and wherein the outer side (1a) is provided with a profile with profile positives and with circumferential grooves (2) designed to the profile depth, the deepest points of which define a circumferential groove level (2a) running parallel to the outer side (1a), characterized in that a groove structure consisting of grooves (3) is formed on the rear side (1b) of the tread (1), the deepest points of which have a distance (a2) from the circumferential groove level (2a), determined perpendicular to the rear side (1b).

2. Running strip (1) according to claim 1, characterized in that the distance (a2) between the deepest points of the grooves (3) of the groove structure and the circumferential groove level (2a) of the circumferential grooves (2) is at least 2.00 mm, in particular at least 3.00 mm.

3. Tread (1) according to claim 1 or 2, characterized in that the groove structure covers the back side (1b) of the tread (1), in particular completely.

4. Tread (1) according to one of claims 1 to 3, characterized in that the groove structure is formed in surface areas or sections of the back (1b) of the tread (1).

5. Running strip (1) according to one of claims 1 to 4, characterized in that the groove structure is formed by omitting areas below circumferential grooves (2). 202402852 6. Tread (1 ) according to one of claims 1 to 5, characterized in that grooves (3) of the groove structure have a rectangular, a V-shaped, an i-shaped or an arc-shaped cross-section.

7. Tread (1 ) according to one of claims 1 to 6, characterized in that the grooves (3) of the groove structure on the back side (1 b) of the tread (1 ) each have a mutual distance (ai) which is 0.50 mm to 5.00 mm.

8. Tread (1 ) according to one of claims 1 to 7, characterized in that the groove structure is a corrugated structure consisting of ribs (3a) with rounded cross-section and rounded grooves (3).

9. Running strip (1 ) according to one of claims 1 to 8, characterized in that the grooves (3) of the groove structure have a cross-section that widens at least section by section in the direction of their groove base.

10. Tread (1 ) according to one of claims 1 to 9, characterized in that the grooves (3) of the groove structure have a depth (t) opposite the back side (1 b) of the tread (1 ) which is 1.00 mm to 10.00 mm.

11. Tread (1 ) according to one of claims 1 to 10, characterized in that the grooves (3) of the groove structure have an opening width (b) of 1.00 mm to 20.00 mm, in particular up to 10.00 mm, determined on the back side (1 b) of the tread (1 ).

12. Running strip (1 ) according to one of claims 1 to 11 , characterized in that grooves (3) of the groove structure run straight, curved or in zigzag or wave form in plan view and in particular parallel to each other. 202402852 13. Tread (1) according to any one of claims 1 to 12, characterized in that grooves (3) of the groove structure extend in the circumferential direction of the tread (1), transversely or obliquely to the circumferential direction of the tread (1).

14. Tread (1) according to any one of claims 1 to 13, characterized in that the groove structure comprises surface areas or sections with different orientations and / or configurations of the grooves (3).

15. Commercial vehicle tire which is cold retreaded with a tread (1 ) according to one or more of claims 1 to 14.

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