Spike and vehicle tire with spikes inserted into the tread

Description

[0001] The invention relates to a spike with which the tread, preferably of a vehicle tire, is to be equipped, comprising a spike body and a spike pin. The spike pin is inserted into the spike body such that one end of the spike pin protrudes beyond the spike body or, when inserted into the tread, beyond the tread surface. The invention also relates to a vehicle tire and a shoe with spikes according to the invention inserted into the tread.

[0002] Spikes and vehicle tires with studded treads are well known to those skilled in the art. Each spike is inserted into a separate, prefabricated stud hole in the tread of the vehicle tire and is typically held in place by its stud body, which is pressed, glued, or vulcanized into the stud hole. The spike pin is inserted into the spike body itself. One end of the spike pin, the so-called spike tip, extends beyond the stud hole and thus beyond the tread surface, thus engaging the winter road surface as the tire rolls. The spike tip typically has a flattened end.

[0003] DE 10 2012 112 658 A1 discloses a spike pin made of hard metals sintered from a powder metallurgical mixture.

[0004] The following is known regarding the surface roughness of metal bodies: In Vikram et al., "Assessment of surface roughness and MMR while machining brass with HSS tool and carbides inserts," Indian Journal of Engineering & Materials Sciences, Vol. 22, June 2015, pages 321-330, it is shown that the average surface roughness Ra of brass can be reduced to 1.42 µm by turning with carbide tools.

[0005] In Piska et al. "On the structural integrity of the Nano-PVD coatings on cutting tools" T. Boukharouba et al. Damage and Fracture Mechanics: Failure Analysis of Engineering Materials and Structures, 2009, pages 195 - 204, an average surface roughness Ra of 1.00 µm to 1.50 µm was achieved when drilling carbon steel with TiN-hard coated cutting tools.

[0006] The average surface roughness is determined according to DIN EN ISO 25178.

[0007] Some average roughnesses achievable with various manufacturing processes can be found in the Wikipedia entry on "surface quality".

[0008] US Pat. No. 3,532,148 A discloses a sintered hard metal spike, which according to a first example contains 64% titanium carbide, 18% molybdenum carbide, and 15% nickel; according to a second example, 60% titanium carbide, 12% vanadium carbide, 9% niobium carbide, and 5% nickel; and according to a third example, 71% titanium carbide, 3% molybdenum carbide, and 17% nickel. The spike is said to have good fracture strength, high abrasion resistance, and low weight.

[0009] The spike pin projection, which is important for ice grip—that is, the extent to which the spike tip extends beyond the surface of the stud hole or the tread surface—is typically set to a length of 1 to 1.5 mm to achieve optimal ice grip. During acceleration or braking, the rear or front edge of the spike tip first comes into contact with the icy road surface, engages the ice, transfers a large portion of the force via the front of the spike tip, and rolls off over the opposite edge.

[0010] The spike pin itself has a "smooth" surface in the state of the art.

[0011] Ice grip, also known as 'ice performance,' is an important parameter for a winter tire and is highly relevant to driving safety. Therefore, efforts are being made to improve ice performance.

[0012] The invention is therefore based on the object of providing a spike and a vehicle tire equipped with these spikes, the ice performance of which is improved.

[0013] The stated object is achieved with regard to the spike according to the invention in that the spike pin has a surface which is at least partially provided with an average roughness Ra in a range from 3 µm to 12 µm.

[0014] According to the invention, the spike pin, which engages the winter road surface, is provided with a medium roughness Ra, at least in some areas, thereby creating a stronger interlock between the road surface and the spike pin. This enables the transmission of higher braking and driving forces, especially on ice. A higher coefficient of friction is achieved. Ice performance is improved.

[0015] It is advantageous if the average roughness Ra lies in a range of 5 µm to 10 µm. Surprisingly, this roughness has proven particularly effective in improving ice performance.

[0016] It is advisable for at least the front side of the end of the spike pin that extends beyond the spike body (corresponding to the 'spike tip') to have a surface that is completely covered with the aforementioned roughness. The front side of the spike body, in contact with the icy road surface, is particularly responsible for transmitting the driving and braking forces. Therefore, it is essential to provide at least the front side with the aforementioned roughness to improve ice performance.

[0017] In a further embodiment of the invention, the entire surface of the end of the spike pin that extends beyond the spike body is provided with a rough surface. This further increases the area of ​​the spike pin that engages with the surface of the winter road, thereby further improving ice performance.

[0018] In another embodiment of the invention, the entire spike pin—including the part of the spike pin that is inserted into the spike body—has a surface that is completely covered with roughness. Although the rough surface of the spike pin located in the spike body is not effective for ice performance, it is easy to provide the entire spike pin with roughness for the production of the spike pin with a rough surface.

[0019] It is advisable for the spike pin to be made of metal, preferably tungsten, a hard metal, or a metal alloy. These materials are suitable for use as spike pins and can also be provided with a rough surface at low cost.

[0020] The invention further relates to a vehicle tire having a tread with stud holes into which studs designed according to the invention are inserted. The vehicle tire is advantageously a pneumatic vehicle tire for a passenger car, a van, or a commercial vehicle.

[0021] The invention further relates to a shoe having a tread with spike holes into which spikes according to the invention are inserted.

[0022] Further features, advantages and details of the invention will now be described in more detail with reference to the schematic drawing: The Fig. 1 shows the cross-section of a spike according to the invention, which is inserted into a spike hole in the tread of a vehicle tire; the Fig. 2 shows a scanned photographic top view of a spike pin with the roughness on its surface.

[0023] The Fig. 1 shows a variant of a conventional spike 1 with a spike body 2 and a spike pin 3, which is inserted into a spike hole in the tread 4 of a vehicle tire. The spike body 2 has an upper flange 2a, a tapered central section 2b, and a base flange 2c. The upper flange 2a is provided in a known manner with a pin hole into which the spike pin 3 is inserted. One end of the spike pin 5 protrudes beyond the spike body 2 or, when fitted into the tread 4, beyond the tread surface 6, and is also called the spike tip.

[0024] The spike body 2 can be rotationally symmetrical or elongated in a conventional manner. The spike pin 3 itself can also be rotationally symmetrical or have an elongated shape, for example, tapering along its longitudinal axis. The spike pin 3 has a front side 7 that is flattened to form edges. The spikes 1 are pressed into stud holes formed in the rubber material of a tread 4 of the pneumatic vehicle tire in a heated mold during tire vulcanization.

[0025] The spike body 2 is made of aluminum or steel and is typically manufactured by turning, cold extrusion, or drop forging. Steel alloys with specific material properties are used to manufacture the spike body 2, particularly for reasons of processability. The spike pin 3 is made of tungsten. The spike pin 3 is designed using a corresponding negative mold, the mold walls of which exhibit the corresponding negative roughness.

[0026] To increase ice performance, at least the front side 7 of the end of the spike pin 5 projecting beyond the spike body 2 has a surface which is completely provided with an average roughness Ra in a range of 5 µm to 10 µm. Here in the Fig. 1 the entire surface of the end of the spike pin 5 projecting beyond the spike body 2 has the roughness (shown toothed for clarity).

[0027] The Fig. 2shows a photographic plan view of an area of ​​the spike pin 3 to illustrate the rough surface of the spike pin, the surface of which is provided with the roughness R a in a range of 5 µm to 10 µm. List of reference numbers

[0028] 1Spike 2aTop flange 2bMiddle section 2cFoot flange 2Spike body 3Spike pin 4Tread 5End of the spike pin / spike pin tip 6Tread surface 7End of the spike tip

Claims

1. Spike (1), with which the tread (4) preferably of a vehicle tyre is to be fitted, comprising a spike body (2) and a spike pin (3), wherein the spike pin (3) is inserted in the spike body (2) in such a way that one end of the spike pin (5) protrudes beyond the spike body (2) or, when it is fitted in the tread (4), protrudes beyond the tread surface (6), characterized in that the spike pin (3) has a surface which is at least partially provided with an average roughness Ra in a range from 3 µm to 12 µm.

2. Spike (1) according to Claim 1, characterized in that the average roughness Ra lies in a range from 5 µm to 10 µm.

3. Spike (1) according to Claim 1 or 2, characterized in that at least the end side (7) of that end of the spike pin (5) which protrudes beyond the spike body (2) has a surface which is completely provided with the roughness Ra.

4. Spike (1) according to one of Claims 1 to 3, characterized in that the entire surface of that end of the spike pin (5) which protrudes beyond the spike body (2) is provided with the roughness Ra.

5. Spike (1) according to one of Claims 1 to 3, characterized in that the entire spike pin (3) has a surface which is completely provided with the roughness Ra.

6. Spike (1) according to one of Claims 1 to 4 or 5, characterized in that the spike pin (3) consists of metal, preferably of tungsten, a hard metal or of a metal alloy.

7. Vehicle tyre with a tread (4) having spike holes in which spikes (1) according to one or more of Claims 1 to 6 are inserted.

8. Vehicle tyre according to Claim 7, characterized in that the vehicle tyre is a pneumatic vehicle tyre for a car, for a van or for a utility vehicle.

9. Shoe with a tread having spike holes in which spikes (1) according to one or more of Claims 1 to 6 are inserted.