Rubber pad structure at tire shoulder of all-steel radial tire and tire

Abstract

The invention discloses an all-steel radial tire shoulder pad rubber structure and a tire. The width of a pad rubber is 35%-45% of the width of a tread, the thickness of the middle part is 6-8 mm, the thickness of the edge is 2-3 mm, the included angle between the edges of the two sides and the center line of the tread is 15-25 degrees, and three positioning points are arranged. By optimizing the size parameters and the positioning mode of the cushion rubber and matching with the gradual change thickness design and the specific material formula, the deformation of the cushion rubber in the tire forming process is reduced. According to the structure, a transition layer is further arranged between the cushion rubber and the first belted layer, and interlayer combination is enhanced. Compared with a traditional structure, the flatness of the belted layer can be improved, end point shear stress is reduced, tire shoulder faults are reduced, and the durability of the tire is improved.

Description

Technical Field

[0001] The invention relates to the field of spraying technology, in particular to a rubber pad structure at the shoulder of an all-steel radial tire and the tire. Background Art

[0002] All-steel radial tires are widely used in trucks, construction vehicles, and other fields due to their high strength, excellent wear resistance, and outstanding load-bearing capacity. The shoulder area is crucial in its structure, and the cushion structure at the shoulder is a key factor affecting tire performance.

[0003] With the development of modern transportation, the speed of heavy-duty vehicles continues to increase, mileage significantly increases, and the weight of transported cargo continues to climb. This puts tires under increasingly demanding operating conditions. The shoulder, as one of the key areas of contact between the tire and the ground, must withstand the complex stresses generated during vehicle operation, including cyclic compression, tension, and shear stresses, as well as impact stress caused by uneven road surfaces. Under these conditions, the shoulder pad structure of traditional all-steel radial tires has exposed numerous problems.

[0004] From a dimensional design perspective, the width and thickness of cushion rubber have often lacked precise consideration, making it difficult to achieve a good fit with the tread and belt layer. If the cushion rubber width is too narrow, it cannot effectively disperse the stress at the belt layer endpoints, resulting in severe stress concentration and easily causing failures such as shoulder delamination and belt layer tearing. If the width is too wide, it may lead to increased tire weight and rolling resistance, thereby affecting the vehicle's fuel economy. In terms of thickness, a cushion rubber of uniform thickness cannot provide targeted buffering and stress distribution when facing complex stresses in different areas. When stress concentrates in the central area, insufficient cushion rubber thickness or improper distribution makes it difficult to effectively absorb energy, which can easily lead to premature wear and even damage.

[0005] In terms of positioning design, previous cushion rubbers were not precisely positioned during the tire building process, lacking effective positioning points. This made the cushion rubber prone to displacement during installation, resulting in its inability to function stably during tire operation. When the cushion rubber's position deviates, the flatness of the belt layer is severely affected, which in turn affects the tire's wear uniformity and overall structural stability, shortening the tire's service life.

[0006] Regarding interlayer connections, the traditional cushion rubber and belt layers, particularly the No. 1 belt layer, lack sufficient strength. Under frequent dynamic loads on the tire, relative displacement and debonding between the layers are prone to occur. Once the interlayer connection fails, shear stress at the belt endpoints increases dramatically, causing localized overheating in the shoulder area and accelerating rubber aging. It can also cause belt delamination, seriously compromising tire safety.

[0007] Based on this, a full-steel radial tire shoulder rubber pad structure and a tire are now provided, which can eliminate the disadvantages of the existing device. Summary of the Invention

[0008] The purpose of the present invention is to provide a rubber pad structure at the shoulder of an all-steel radial tire and the tire, which solves the problem of inconvenience in use in the prior art.

[0009] To achieve the above object, the present invention provides the following technical solutions:

[0010] A cushion rubber structure at the shoulder of an all-steel radial tire, wherein the cushion rubber width W is 35%-45% of the tread width, the middle thickness H1 is 6-8mm, the edge thickness H2 is 2-3mm, and the angle α between the two side edges and the tread centerline is 15°-25°. The cushion rubber is provided with three positioning points, namely a center point A and bilaterally symmetrical points B and C. The center point A is located on the centerline of the cushion rubber width direction, and the distance L1 from the front edge of the cushion rubber is 40%-50% of the cushion rubber length. The horizontal distance L2 between the bilaterally symmetrical points B and C and the center point A is 20%-30% of the cushion rubber width, and the vertical distance L3 is 1 / 3-1 / 2 of the cushion rubber thickness.

[0011] On the basis of the above technical solutions, the present invention also provides the following optional technical solutions:

[0012] In an optional solution, the cushion rubber width W is 40% of the tread width, the middle thickness H1 is 7 mm, the edge thickness H2 is 2.5 mm, and the angle α between the two side edges and the tread centerline is 20°.

[0013] In an optional solution, the pad rubber adopts a gradient thickness design with a thickness change rate of 0.8-1.2 mm / cm, and gradually becomes thinner from the middle of the pad rubber to the edge.

[0014] In an optional solution: the distance L1 between the center point A and the front edge of the pad rubber is 45% of the length of the pad rubber, the horizontal distance L2 between the two symmetrical points B and C and the center point A is 25% of the width of the pad rubber, and the vertical distance L3 is 1 / 3 of the thickness of the pad rubber.

[0015] In an optional solution, the cushion rubber material is a blend of natural rubber and styrene-butadiene rubber, wherein the mass fraction of natural rubber is 60%-70%, the mass fraction of styrene-butadiene rubber is 30%-40%, and carbon black, white carbon black, accelerator and sulfur are added.

[0016] In an optional solution, the amount of carbon black added is 40-50 parts, the amount of white carbon black added is 10-15 parts, the amount of accelerator added is 1-3 parts, and the amount of sulfur added is 1.5-2.5 parts.

[0017] In an optional solution: a transition layer is provided between the cushion rubber and the No. 1 belt layer, the thickness of the transition layer is 0.5-1.0 mm, and it is made of a high-viscosity rubber material, the Shore hardness of the high-viscosity rubber material is 65-75 degrees, and the 180° peel strength is ≥8N / mm.

[0018] An all-steel radial tire comprising the above-mentioned cushion rubber structure, wherein a second belt layer is provided on one side of the first belt layer, the flatness deviation between the first belt layer and the second belt layer is less than 0.8 mm, and the shear stress at the end point of the belt layer is less than 1.4 MPa

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The shoulder cushion structure and tire design of this all-steel radial tire, through precise dimensional design, scientific positioning, and rational material composition, effectively address cushion deformation and positioning point displacement issues during the molding process. Measured data show that this structure reduces cushion deformation by 20%-30%, improves the flatness of the first and second belt layers by 15%-20%, reduces shear stress at the belt end points by 18%-25%, reduces the incidence of tire shoulder failures by 30%-40%, and increases durability test mileage by 15%-20%. Furthermore, the transition layer strengthens the bond between the cushion and belt, ensuring overall tire structural stability and providing reliable assurance for the quality and performance of the all-steel radial tire. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a cross-sectional view of the present invention.

[0022] Reference numerals:

[0023] Foot pad 100, transition layer 200, first belt layer 300. DETAILED DESCRIPTION

[0024] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without creative work are within the scope of protection of the present invention.

[0025] Example 1

[0026] (1) Preparation of pad rubber materials

[0027] Raw material weighing: Weigh 60kg of natural rubber, 40kg of styrene-butadiene rubber, 40kg of carbon black, 10kg of white carbon black, 1.5kg of accelerator, and 1.5kg of sulfur. Place the raw materials in special containers and mark them.

[0028] Mixing: Place natural rubber and styrene-butadiene rubber in an internal mixer at an initial temperature of 95°C and a speed of 55 rpm for 2.5 minutes. Add carbon black and silica in sequence and continue mixing for another 4 minutes. Add accelerator and sulfur, raise the temperature to 135°C, adjust the speed to 35 rpm, and mix for 1.5 minutes. After mixing, discharge the rubber and cool to room temperature on a cooling rack.

[0029] (2) Cushion size forming

[0030] Extrusion: Feed the cooled rubber into a screw extruder with screw temperatures of 105°C (zone 1), 115°C (zone 2), and 125°C (zone 3), and a die head temperature of 135°C. Adjust the screw speed and die die to ensure that the cushion rubber width W is 35% of the tread width (assuming a tread width of 550mm), or 192.5mm; the center thickness H1 is 6mm, the edge thickness H2 is 2mm, and the thickness variation rate is 0.8mm / cm; and the angle α between the two side edges and the tread centerline is 15°.

[0031] Marking of positioning points: Determine the length of the rubber pad (assuming 280mm), mark the center point A at the center line of the rubber pad width, at a distance L1 from the front edge that is 40% of the rubber pad length, i.e. 112mm; with A as the reference, mark symmetrical points B and C at symmetrical positions on both sides, at a horizontal distance L2 that is 20% of the rubber pad width, i.e. 38.5mm, and a vertical distance L3 that is 1 / 3 of the rubber pad thickness (about 2mm).

[0032] (3) Assembly of rubber pad and belt layer

[0033] Preparation of transition layer: High-viscosity rubber material is pressed into a 0.5 mm thick film using a calender. Its Shore hardness is tested to be 65 degrees and its 180° peel strength is 8 N / mm.

[0034] Assembly: First, lay the No. 1 belt layer on the tire building drum and apply the transition layer film. Place the semi-finished cushioning rubber with positioning points on the transition layer and use a positioning tool to align the positioning pins with the positioning points. First, apply 1.5MPa pressure to the center of the cushioning rubber for 5 seconds; then apply 1.0MPa pressure to the edges for 3 seconds. Then, lay the No. 2 belt layer and other components to complete the tire blank.

[0035] (4) Performance testing

[0036] After testing, the size deviation of the cushion rubber is within ±0.1mm (width, thickness) and ±0.5° (angle); the tensile strength of the rubber material is 18.5MPa, and the elongation at break is 520%; the flatness deviation of the No. 1 belt layer and the No. 2 belt layer is 0.7mm, and the maximum shear stress at the end point of the belt layer is 1.38MPa; the incidence rate of tire shoulder failure is reduced by 32% compared with traditional tires, and the durability performance test mileage is increased by 16%.

[0037] 2. Example 2

[0038] (1) Preparation of pad rubber materials

[0039] Raw material weighing: Take 70kg of natural rubber, 30kg of styrene-butadiene rubber, 50kg of carbon black, 15kg of white carbon black, 3kg of accelerator, and 2.5kg of sulfur, store them separately and label them.

[0040] Mixing: Place natural rubber and styrene-butadiene rubber in an internal mixer at an initial temperature of 105°C and a speed of 65 rpm for 3.5 minutes. Add carbon black and silica and mix for 6 minutes. Add accelerator and sulfur, raise the temperature to 145°C, and mix at a speed of 45 rpm for 2.5 minutes. Discharge the rubber and cool to room temperature.

[0041] (2) Cushion size forming

[0042] Extrusion: The rubber compound is fed into the extruder, with screw temperatures set at 115°C in zone 1, 125°C in zone 2, and 135°C in zone 3, and the die head temperature at 145°C. Adjustments are made to ensure that the cushion rubber width W is 45% of the tread width (assuming a tread width of 650 mm), or 292.5 mm. The center thickness H1 is 8 mm, the edge thickness H2 is 3 mm, and the thickness variation rate is 1.2 mm / cm. The angle α between the two edges and the tread centerline is 25°.

[0043] Marking of positioning points: Determine the length of the rubber pad (assuming 320mm), and mark the center point A at the center line of the rubber pad width, where the distance L1 from the front edge is 50% of the rubber pad length, i.e. 160mm; with A as the reference, mark the symmetrical points B and C at the symmetrical positions on both sides, where the horizontal distance L2 from A is 30% of the rubber pad width, i.e. 87.75mm, and the vertical distance L3 is 1 / 3 of the rubber pad thickness (about 2.7mm).

[0044] (3) Assembly of rubber pad and belt layer

[0045] Preparation of transition layer: High-viscosity rubber material is calendered into a film with a thickness of 1.0 mm, a Shore hardness of 75 degrees, and a 180° peel strength of 12 N / mm.

[0046] Assembly: After laying the No. 1 belt and transition layer film on the building drum, the semi-finished rubber pad with positioning points is placed and positioned. First, apply 2.0 MPa pressure to the center of the rubber pad for 8 seconds; then, apply 1.5 MPa pressure to the edges for 5 seconds. Then, lay the No. 2 belt and other components to complete the tire blank.

[0047] (4) Performance testing

[0048] Tests show that the rubber pad size meets the requirements; the rubber material has a tensile strength of 19.2MPa and an elongation at break of 530%; the flatness deviation between the No. 1 and No. 2 belt layers is 0.6mm, and the maximum shear stress at the belt layer endpoints is 1.32MPa; the incidence of tire shoulder failures is reduced by 38% compared to traditional tires, and the durability performance test mileage is increased by 20%.

[0049] 3. Example 3

[0050] (1) Preparation of pad rubber materials

[0051] Raw material weighing: weigh 63kg of natural rubber, 37kg of styrene-butadiene rubber, 43kg of carbon black, 13kg of white carbon black, 2.2kg of accelerator, and 2kg of sulfur, and make sure to separate the raw materials.

[0052] Mixing: Place natural rubber and styrene-butadiene rubber in an internal mixer at an initial temperature of 102°C and a speed of 62 r / min for 3 minutes. Add carbon black and silica and mix for 5.5 minutes. Then add accelerator and sulfur, raise the temperature to 142°C, and mix at a speed of 42 r / min for 2.2 minutes. Allow the rubber to cool and set aside.

[0053] (2) Cushion size forming

[0054] Extrusion molding: Rubber material enters the extruder, screw temperature: Zone 1 112°C, Zone 2 122°C, Zone 3 132°C, die head temperature 142°C. Control the cushion rubber width W to 38% of the tread width (assuming a tread width of 620mm), or 235.6mm; center thickness H1 is 7.2mm, edge thickness H2 is 2.6mm, and the thickness variation rate is 1mm / cm; the angle α between the two side edges and the tread centerline is 18°.

[0055] Marking of positioning points: Determine the length of the rubber pad (assuming 310mm), and mark the center point A at the center line of the rubber pad width, where the distance L1 from the front edge is 43% of the rubber pad length, i.e. 133.3mm; with A as the reference, mark the symmetrical points B and C at the symmetrical positions on both sides, where the horizontal distance L2 from A is 23% of the rubber pad width, i.e. 54.2mm, and the vertical distance L3 is 1 / 3 of the rubber pad thickness (about 2.4mm).

[0056] (3) Assembly of rubber pad and belt layer

[0057] Preparation of transition layer: High-viscosity rubber material is calendered into a film with a thickness of 0.7 mm, a Shore hardness of 72 degrees, and a 180° peel strength of 9 N / mm.

[0058] Assembly: After the first belt and transition layer are laid on the building drum, the rubber cushion is placed and positioned. First, a pressure of 1.7 MPa is applied to the center of the cushion for 7 seconds. Then, a pressure of 1.3 MPa is applied to the edges for 4 seconds. Finally, the remaining tire components are laid to form the tire blank.

[0059] (4) Performance testing

[0060] After inspection, all dimensions of the cushion rubber meet the standards; the tensile strength of the rubber material is 18.8MPa, and the elongation at break is 515%; the flatness deviation between the No. 1 belt layer and the No. 2 belt layer is 0.75mm, and the maximum shear stress at the end points of the belt layer is 1.36MPa; the incidence rate of tire shoulder failure is reduced by 34% compared with traditional tires, and the durability performance test mileage is increased by 17%.

[0061] The above multiple embodiments demonstrate the implementation of the technical solution from different perspectives.

[0062] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A rubber pad structure at the shoulder of an all-steel radial tire, characterized in that: The width W of the cushion rubber is 35%-45% of the tread width, the middle thickness H1 is 6-8mm, the edge thickness H2 is 2-3mm, and the angle α between the two side edges and the center line of the tread is 15°-25°; the cushion rubber is provided with three positioning points, namely the center point A and the bilaterally symmetrical points B and C. The center point A is located on the center line in the width direction of the cushion rubber, and the distance L1 from the front edge of the cushion rubber is 40%-50% of the length of the cushion rubber. The horizontal distance L2 between the bilaterally symmetrical points B and C and the center point A is 20%-30% of the cushion rubber width, and the vertical distance L3 is 1 / 3-1 / 2 of the cushion rubber thickness.

2. The shoulder rubber cushion structure of the all-steel radial tire according to claim 1, characterized in that: The width W of the cushion rubber is 40% of the tread width, the middle thickness H1 is 7 mm, the edge thickness H2 is 2.5 mm, and the angle α between the two side edges and the tread centerline is 20°.

3. The shoulder rubber cushion structure of the all-steel radial tire according to claim 1, characterized in that: The padding rubber adopts a gradient thickness design with a thickness change rate of 0.8-1.2 mm / cm, and gradually becomes thinner from the middle of the padding rubber to the edge.

4. The shoulder rubber cushion structure of the all-steel radial tire according to claim 1, characterized in that: The distance L1 between the center point A and the front edge of the pad rubber is 45% of the length of the pad rubber, the horizontal distance L2 between the two symmetrical points B and C and the center point A is 25% of the width of the pad rubber, and the vertical distance L3 is 1 / 3 of the thickness of the pad rubber.

5. The shoulder rubber cushion structure of the all-steel radial tire according to claim 1, characterized in that: The pad rubber material is a blend of natural rubber and styrene-butadiene rubber, wherein the mass fraction of natural rubber is 60%-70% and the mass fraction of styrene-butadiene rubber is 30%-40%, and carbon black, white carbon black, accelerator and sulfur are added.

6. The shoulder rubber cushion structure of the all-steel radial tire according to claim 5, characterized in that: The added amount of carbon black is 40-50 parts, the added amount of white carbon black is 10-15 parts, the added amount of accelerator is 1-3 parts, and the added amount of sulfur is 1.5-2.5 parts.

7. The shoulder rubber cushion structure of the all-steel radial tire according to claim 1, characterized in that: A transition layer is provided between the cushion rubber and the first belt layer. The thickness of the transition layer is 0.5-1.0 mm and the layer is made of a high-viscosity rubber material. The Shore hardness of the high-viscosity rubber material is 65-75 degrees and the 180° peel strength is ≥8N / mm.

8. A tire comprising the cushion rubber structure according to any one of claims 1 to 7, characterized in that: A second belt layer is provided on one side of the first belt layer, the flatness deviation between the first belt layer and the second belt layer is less than 0.8 mm, and the shear stress at the end points of the belt layer is less than 1.4 MPa.

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