A steel cord carcass light truck tire

Abstract

The present invention relates to the technical field of tires, and particularly to a steel cord carcass light truck tire. A steel cord carcass light truck tire, the tire comprising a crown, a belt layer, a carcass, an inner liner, a sidewall and a bead, the bead comprising an upper apex rubber, a lower apex rubber and a steel wire ring, the carcass bypassing the steel wire ring and turning up outside the upper apex rubber; and a layer of separator film is pre-coated at the turning-up end point; after the carcass is turned up, a layer of chafing strip is further adhered, the width of the chafing strip being 30 mm - 60 mm and the thickness being 0.4 mm - 1.5 mm, the center position of the chafing strip being approximately located at the turning-up end point of the carcass, the upper end point of the chafing strip avoiding the end point of the upper apex rubber by more than 10 mm, and the lower end point not being lower than the horizontal height where the Q point is located. This tire can meet the high load-carrying requirements of the market, and at the same time has low production cost, low rolling resistance, good comfort and handling performance. The present invention realizes the industrial production of steel cord carcass light truck tires, and has a high production qualification rate and good market feedback.

Description

Technical Field

[0001] The invention relates to the technical field of tires, in particular to a light-duty truck tire with a steel wire carcass. Background Art

[0002] Light truck tires are designed mainly for mini cars or light commercial vehicles. They are a type of truck tire. Large truck tires usually use steel wire materials as the tire body. Light truck tires are between trucks and cars. They can be used for both passenger and commercial purposes. Influenced by vehicle usage and manufacturing technology, light truck tires usually use fiber materials as the tire body.

[0003] However, many light truck tires also have high requirements for load-bearing capacity in actual use. When using fiber carcasses, two or three layers of carcass materials are required, which has high production costs and large rolling resistance. If steel wire materials are used instead, only one layer of carcass is needed, and a high-strength and low-heat radial tire carcass structure can be obtained, which can control production costs and reduce rolling resistance. At the same time, due to the excellent strength and impact resistance of steel wire materials, it can also meet high load requirements.

[0004] Since the last century, many advanced tire companies at home and abroad have tried to use steel wire materials as tire bodies in light-duty truck tires and even passenger car tires. However, due to the high bending stiffness and strong resilience of steel wire materials, industrial production is difficult. Even if industrial production is barely achieved, the pass rate is low and there are constant complaints from customers in the market.

[0005] There are three main areas where problems are most likely to occur in the production and use of steel wire carcass light truck tires: the flex area, the upper bead area, and the lower bead area. The technical difficulties to be solved by the present invention are also mainly in these three areas. The three areas mentioned are only for the convenience of explanation in this article and are not a clear definition of the tire parts.

[0006] ① The bending area is prone to tire line jump, tire body bending, sparse lines, fatigue damage and various bubbles.

[0007] ② The upper bead area is prone to various early mechanical damages such as cracking and debonding;

[0008] ③ The lower tire bead area is prone to various types of voids, material deformation and bubbles caused by tire body wrapping. Summary of the invention

[0009] In order to solve the above technical problems, the present invention provides a steel wire carcass light-duty truck tire, which can meet the high load-bearing requirements of the market and has low production costs, low rolling resistance, and good comfort and handling performance.

[0010] To achieve the above object, the present invention adopts the following technical solutions:

[0011] A steel cord carcass light truck tire, which includes a tread crown, a belt layer, a carcass, an inner liner, a sidewall and a bead. The bead includes an upper apex rubber, a lower apex rubber and a steel wire ring. The carcass bypasses the steel wire ring and is turned up to the outside of the upper apex rubber. The turned-up end point is 20-30 mm radially upward from the Q point of the heel exhaust line. The overall thickness near the turned-up end point of the carcass needs to be more than 20 mm; and a layer of separator film is pre-coated at the turned-up end point. The width of the separator film is 20 mm - 80 mm, and the thickness is 0.4 mm - 0.8 mm. The radially height distance between the outer end point and the inner end point of the separator film is more than 5 mm; and a layer of bead filler is applied after the carcass is turned up. The width of the bead filler is 30 mm - 60 mm, and the thickness is 0.4 mm - 1.5 mm. The center position of the bead filler is approximately located at the turned-up end point of the carcass. The upper end point of the bead filler avoids the end point of the upper apex rubber by more than 10 mm, and the lower end point is not lower than the horizontal height where the Q point is located.

[0012] Preferably, the separator film is coated at the turned-up end point. The outer side contacts the sidewall, and the inner side contacts the triangle. The width of the separator film is between 30 - 60 mm. The width of the inner side is slightly wider than that of the outer side, and the end points of the inner and outer sides are staggered by 5 - 10 mm; the thickness of the separator film is between 0.5 - 1.0 mm, and the thickness tolerance of the upper and lower films covering the steel wire.

[0013] Preferably, the inner liner is composed of a transition layer and an air retention layer. The transition layer has the same formula as the carcass steel wire rubber. The thickness of the inner liner in the flexing area of the finished tire is not less than 2 mm; preferably, the thickness of the inner liner in the flexing area of the finished tire is close to the thickness of the sidewall.

[0014] Preferably, the upper apex rubber is relatively soft, with a Shore hardness between 50 and 70, and the lower apex rubber is relatively hard, with a Shore hardness between 85 and 95; more preferably, the width of the base of the lower apex rubber matches the width of the upper end of the steel wire ring, and the lower end shape of the lower apex rubber is designed to be as wide, thick and full as possible.

[0015] Preferably, the sidewall includes a sidewall rubber and a shoulder pad rubber, and the width of the interface between the sidewall rubber and the shoulder pad rubber is more than 15 mm.

[0016] Preferably, the material of the bead filler can be nylon, polyester or steel wire; preferably, the cord angle of the bead filler semi-finished product is 45 ± 10 degrees.

[0017] Preferably, a steel ring winding cloth is evenly wound around the steel wire ring in the circumferential direction. The width of the steel ring winding cloth is between 5 mm - 15 mm, the thickness is 0.4 mm - 0.6 mm, and the material is nylon.

[0018] Preferably, the crown includes tread rubber, base rubber and shoulder rubber, which are combined into two-section tire embryos when the crown, cap layer and belt layer are formed; the sidewalls include shoulder pad rubber and sidewall rubber, the shoulder pad rubber is padded into the lower end of the belt layer, and the sidewall rubber is connected to the shoulder pad rubber and the crown; the liner includes an air retention layer and a transition layer, and the carcass is between the liner and the sidewalls.

[0019] As a preference, the carcass cord strength is between 21000-60000N / 10cm; when the calendering density is 70-80 cords / 10cm, the strength of a single steel cord is between 300-750N; and the bending stiffness of the steel cord is 60Nmm 2 -100Nmm 2 .

[0020] Preferably, the carcass cord has a thickness of 1.0 mm to 1.5 mm after rubber coating, and the thickness tolerance of the upper and lower rubber sheets covering the steel wire is ±0.02 mm.

[0021] Due to the adoption of the above technical solution, the tire can meet the high load-bearing requirements of the market, and at the same time has low production cost, low rolling resistance, good comfort and handling performance. The present invention realizes the industrialized production of steel wire carcass light-duty truck tires, has a high production qualification rate, and has good market feedback. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic cross-sectional view of the main components of a light-duty truck tire with a steel wire carcass;

[0023] Figure 2 It is a schematic diagram of the positions of the three regions of the bending region, the upper bead region, and the lower bead region according to the present invention;

[0024] Figure 3 It is a schematic diagram of the bending area of the present invention;

[0025] Figure 4 A schematic diagram of the upper tire bead area of the present invention;

[0026] Figure 5 is a schematic diagram of the lower tire bead area of the present invention;

[0027] In the above figures, 1, crown; 2, cap layer; 3, belt layer; 4, carcass; 5, inner liner; 6, sidewall; 7, bead cover; 8, isolation film; 9, bead. DETAILED DESCRIPTION

[0028] The specific implementation modes of the present invention will be described in detail below in conjunction with the accompanying drawings.

[0029] like Figure 1As shown in the figure, the present invention provides a steel cord carcass light truck radial tire. The components of the longitudinal section of the tire from top to bottom are: tread 1, crown ply 2, belt layer 3, carcass 4, inner liner 5, sidewall 6, chafer ply 7, separating ply 8, and bead 9.

[0030] The core technology of the present invention is the application of steel cord carcass in light truck radial tires. Therefore, the selection and application of steel cord carcass varieties are the design keys. Regarding the selection of steel cord varieties, the strength, fatigue resistance, and bending stiffness of the steel wire must be considered.

[0031] Regarding strength, the strength of steel wire is usually several times that of polyester materials. Therefore, using steel wire as the carcass is beneficial to enhancing the tire strength, improving the impact resistance of the tire, and thus enhancing the load-bearing capacity of the tire. However, we must also consider the producibility and economic benefits. Therefore, we need to select steel wire with appropriate strength according to the actual needs of tire products. After the steel wire is calendered into cord fabric and applied to the tire, the cord fabric strength is ultimately considered in tire application. The cord fabric strength refers to the product of the single-strand strength of the cord and the calendering density. Therefore, to ensure the cord fabric strength, in addition to selecting steel wire with appropriate strength, an appropriate cord fabric density also needs to be matched.

[0032] Most light truck radial tires are 8PR, 10PR, 12PR, and the load index is usually below 121. The cord fabric strength of the target product is between 21000 - 60000 N / 10 cm. When the calendering density is between 70 - 80 cords / 10 cm, the single-strand strength of the steel wire is between 300 - 750 N. The bending stiffness of the steel cord is 60 Nmm 2 -100 Nmm 2

[0033] Such as Figure 3As shown, in the flexing area, the crown 1 includes tread rubber 11, base rubber 12, and shoulder rubber 13, and is combined with the cap ply 2 and belt 3 to form a two-stage green tire during molding. The sidewall 6 includes shoulder cushion rubber 61 and sidewall rubber 62. The shoulder cushion rubber 61 is inserted at the lower end of the belt 3, and the sidewall rubber 62 is connected to the shoulder cushion rubber 61 and the crown 1. The inner liner 5 includes an air retention layer 51 and a transition layer 52, and the carcass 4 is located between the inner liner 5 and the sidewall 6. The thickness of the flexing area is usually designed to be relatively thin. Since the carcass 4 is made of steel wire, there is a difference in the extensibility matching between the steel wire and the surrounding rubber material during tire inflation deformation. If the rubber material on one side of the carcass is too thin, the steel wire is likely to penetrate through the rubber material to form a jump wire. Generally, the sidewall thickness of a semi-steel tire in this area is above 3 mm, but the inner liner thickness is usually relatively thin. Therefore, for steel wire carcass tires, the thickness of the inner liner needs to be strengthened in this area. The normal thickness of the inner liner semi-finished product needs to be above 3 mm, and at the same time, the modulus of the transition layer 52 also needs to be appropriately increased to resist the jump of the steel wire. In addition, due to the large deformation in the flexing area, this area is also the most challenging position for testing the fatigue resistance of the carcass ply. If the fatigue resistance of the carcass ply is insufficient, the tire is prone to early fatigue damage.

[0034] As Figure 4As shown, in the upper bead area, the bead 9 includes an upper chafer 91 and a lower chafer 92. The upper chafer 91 is relatively soft, with a Shore hardness between 50 and 70, and the lower chafer 92 is relatively hard, with a Shore hardness between 85 and 95. To improve the adhesion between the chafer and the carcass and prevent the metal at the end of the steel carcass from being exposed, a layer of separator film 8 is pre-coated at the turned-up end of the carcass 4. The width of the separator film 8 is 20 mm - 80 mm, and the thickness is 0.4 mm - 0.8 mm. It needs to have good adhesion. To prevent the overlap gap at the end from being too large, the radial height distance between the outer end 8a and the inner end 8b of the separator film 8 is more than 5 mm. The turned-up end 4a of the carcass 4 should not be too low. When it is too low, the rebound stress of the carcass is large, making the forming and turning-up difficult, and it is also easy to bounce off during the placement of the green tire, resulting in bead voids in the finished tire. The turned-up end 4a should not be too high either. In the upper bead area, generally, the material thickness and rigidity design become smaller and the flexural deformation becomes larger as it goes up. When it is too high, due to the difference in rigidity matching between the steel carcass and other composite materials, the turned-up end 4a is likely to separate from other composite materials or the chafer breaks, showing bead cracks on the tire. Therefore, on the premise of ensuring that the turned-up does not bounce off, the landing point of the turned-up end 4a is preferably set in an area with relatively large rigidity and small deformation, approximately 25 mm above the Q point of the bead heel vent line in the radial direction. To further prevent the rebound of the turned-up carcass 4, a layer of flange wrapper 7 is applied after the carcass 4 is turned up. The width of the flange wrapper 7 is 30 mm - 60 mm, and the thickness is 0.4 mm - 1.0 mm. The material can be nylon, polyester, or steel. The center position of the flange wrapper 7 is approximately located at the carcass end 4a. The upper end 7a of the flange wrapper 7 is more than 10 mm away from the chafer end, and the lower end 7b is not lower than the horizontal height of the Q point. The sidewall 6 includes a sidewall rubber 62 and a shoulder pad rubber 63, and the width of the interface between the sidewall rubber 62 and the shoulder pad rubber 63 is more than 15 mm. To avoid various early mechanical damages such as cracking and voids in the upper bead area, a relatively large thickness needs to be designed in this area to support the bead rigidity, and the overall thickness near the turned-up end 4a of the carcass needs to be more than 20 mm.

[0035] As Figure 5As shown in the figure, in the lower bead area, the bead 9 includes a lower chafer 92, a bead wire 93, and a bead wire wrap 94. To prevent wear between the bead wire 93 and the carcass 4 made of two different metal materials and to keep the arrangement of the bead wire from becoming loose, a bead wire wrap 94 is wound around the bead wire 93 in a circumferential direction evenly. The width of the bead wire wrap 94 is between 5 mm and 15 mm, the thickness is between 0.4 mm and 0.6 mm, and the material is nylon. The width of the base of the lower chafer 92 should match the width of the upper end of the bead wire 93. If it is too loose or too tight, air will be trapped due to the fitting gap. Additionally, since the bending stiffness of the steel carcass 4 is relatively larger than that of a fiber carcass, the steel carcass does not wrap tightly against the bead wire 93 and the lower chafer 92 like a fiber carcass. The overall shape of the steel carcass is arc-shaped, which results in a certain gap at some positions between the carcass 4 and the bead 9. In particular, air is likely to be trapped at positions AB on the left and right sides of the bead wire. Therefore, the lower end of the lower chafer 92 is designed to be as wide, thick, and full as possible, which not only reduces the trapped air in the gap but also helps to improve the bead rigidity.

[0036] Implementing production in accordance with the manner of the present invention enables the industrial production of steel carcass light truck tires. The production qualification rate usually remains above 97%, the product performance is stable, meeting the high load-bearing requirements of the market, and the machine tool test results are better than those of ordinary fiber carcass tires.

[0037] The present invention selects the 215 / 70R15C 8PR specification for development and testing. The carcass 4 uses 1 + 5 * 0.18UT steel wires. The forming drum width is calculated according to the cord elongation coefficient of the carcass of 1.03. The calendering thickness is 1.3 mm, and the calendering density is 80 wires / 10 cm. The width of the carcass 4 is designed to be 520 mm, and the rear endpoint 4a of the carcass wrap is 25 mm radially upward at the Q point.

[0038] The information of the carcass steel wire material is shown in Table 1.

[0039] Table 1

[0040] Breaking force of single strand N ≥540 Cord diameter mm 0.54 Linear density pcs / dm 1.2 Twist pitch mm 11±5％ Twist direction / S Bending stiffness <![CDATA[Nmm 2 > 62

[0041] The sidewall 6 has a width of 160 mm. The thickness of the semi-finished product in the flexing area is 4 mm, and the thickness of the semi-finished product in the upper bead area is 6 mm. The width of the shoulder pad rubber is 15 mm, and the width of the shoulder pad rubber is 30 mm.

[0042] The separating rubber sheet 8 is wrapped around the cord end. The width is 40 mm, the outer side width is 15 mm, the inner side width is 25 mm, and the thickness is 0.5 mm.

[0043] The thickness of the inner liner 5 is designed to be 3.5 mm, where the thickness of the transition layer is 2.0 mm and the thickness of the air retention layer is 1.5 mm. The width of the air retention layer is 20 mm wider than that of the transition layer, and the overall width of the inner liner 5 is 460 mm.

[0044] The Shore hardness of the upper chafer of the bead 9 is 62, the Shore hardness of the lower chafer is 90, and the height of the entire chafer is 55 mm. The wire bead 92 is arranged in the form of 5 + 6 + 5 + 4. The width of the bead wrap 93 is 10 mm and it is evenly wound around the wire bead for one circumferential turn.

[0045] The bead filler 7 is made of nylon 930dtex / 2F94 material, with a width of 40 mm, and is 15 mm lower than the radial height of the chafer tip. The machine tool performance test results of the steel wire carcass light truck tire produced according to Scheme 1 are shown in Table 2.

[0046] The test method for endurance 1 is as follows: In the first 34 h, it is tested according to the normal endurance 4 standard. After 34 h, the air pressure remains unchanged, the speed is adjusted to 80 km / h, and for every additional 4 h, the load is increased by 10%. After the load reaches 200%, it will not be increased anymore until it is damaged.

[0047] Table 2

[0048] Test item Test method Index requirement Result Tire weight / / 14.2 kg Endurance 1 Customized ≥90 h (outer tire normal) 200 h 32 min, crack at the upper end of the bead Endurance 2 GB / T 4501 ≥55 h (outer tire normal) 80 h, outer tire normal High speed GB / T 4501 ≥1 h 15 min (outer tire normal) 1 h 40 min, bulge at the crown Strength GB / T 4501 ≥676.2J Not penetrated, 774 J at the fifth point Rolling resistance coefficient ISO 28580 / 8.2

[0049] The above is the description of the embodiments of the present invention. Through the above description of the disclosed embodiments, those skilled in the art can implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A light truck tire with a steel cord carcass, the tire comprising a tread (1), a belt layer (3), a carcass (4), an inner liner (5), a sidewall (6) and a bead (9), the bead (9) comprising an upper apex (91), a lower apex (92) and a bead wire (93), characterized in that, The described carcass (4) bypasses the bead (93) and is turned up to the outside of the upper chafer (91). The turned-up end point (4a) is located 20 - 30 mm radially upward from the Q point of the heel vent line. The overall thickness near the turned-up end point (4a) of the carcass (4) is above 20 mm. And a layer of separator film (8) is pre-coated at the turned-up end point (4a). The width of the separator film (8) is 20 mm - 80 mm, and the thickness is 0.4 mm - 0.8 mm. The radially height distance between the outer end point (8a) and the inner end point (8b) of the separator film (8) is more than 5 mm. And after the carcass (4) is turned up, a layer of chafing strip (7) is applied. The width of the chafing strip (7) is 30 mm - 60 mm, and the thickness is 0.4 mm - 1.5 mm. The center position of the chafing strip (7) is roughly located at the turned-up end point (4a) of the carcass (4). The upper end point (7a) of the chafing strip (7) is more than 10 mm away from the end point of the upper chafer (91), and the lower end point (7b) is not lower than the horizontal height where the Q point is located. The separator film (8) is coated at the turned-up end point (4a), with the outer side in contact with the sidewall (6) and the inner side in contact with the upper chafer (91). The width of the separator film (8) is between 30 - 60 mm, the width of the inner side is slightly wider than that of the outer side, and the end points of the inner side and the outer side are staggered by 5 - 10 mm.

2. A light truck tire with a steel carcass according to claim 1, characterized in that, The described inner liner (5) is composed of a transition layer (51) and an air retention layer (52). The transition layer (51) has the same rubber compound formula as that of the carcass (4) wire rubber. The thickness of the inner liner (5) in the flexing area of the finished tire is not less than 2 mm.

3. A light truck tire with a steel cord carcass according to claim 1, characterized in that, The thickness of the inner liner (5) in the flexing area of the finished tire is close to the thickness of the sidewall (6).

4. A light truck tire with a steel cord carcass according to claim 1, characterized in that, The upper chafer (91) is relatively soft, with a Shore hardness between 50 and 70. The lower chafer (92) is relatively hard, with a Shore hardness between 85 and 95.

5. A light truck tire with a steel carcass according to claim 1, characterized in that, The width of the base of the lower chafer (92) should match the width of the upper end of the bead (93). The shape of the lower end of the lower chafer (92) is designed to be wide, thick and full.

6. A light truck tire with a steel carcass according to claim 1, characterized in that, The sidewall (6) includes a sidewall rubber (62) and a shoulder pad rubber. The width of the interface between the sidewall rubber (62) and the shoulder pad rubber is more than 15 mm.

7. A light truck tire with a steel cord carcass according to claim 1, characterized in that, The material of the chafing strip (7) is nylon, polyester or steel wire.

8. A light truck tire with a steel cord carcass according to claim 1, characterized in that, The semi-finished product cord angle of the chafing strip (7) is 45 ± 10 degrees.

9. A light truck tire with a steel cord carcass according to claim 1, characterized in that, A steel ring winding cloth (94) is wound evenly around the bead (93) in the circumferential direction. The width of the steel ring winding cloth (94) is between 5 mm - 15 mm, the thickness is 0.4 mm - 0.6 mm, and the material is nylon.

10. A light truck tire with a steel carcass according to claim 1, characterized in that, The tread crown (1) includes a tread rubber (11), a base rubber (12) and a shoulder rubber (13). When the tread crown (1) is formed with the crown ply (2) and the belt layer (3), it is combined into a two-stage tire blank. The sidewall (6) includes a shoulder pad rubber (61) and a sidewall rubber (62). The shoulder pad rubber (61) is inserted under the lower end of the belt layer (3), and the sidewall rubber (62) is connected to the shoulder pad rubber (61) and the tread crown (1).

11. A light truck tire with a steel cord carcass according to claim 1, characterized in that, The cord strength of the carcass (4) is between 21,000 - 60,000 N / 10 cm; when the calendering density is between 70 - 80 cords / 10 cm, the single wire strength is between 300 - 750 N; the bending stiffness of the steel cord is 60 Nmm 2 - 100 Nmm 2 .

12. A light truck tire with a steel cord carcass according to claim 1, characterized in that, The thickness of the carcass (4) cord fabric after being coated with rubber is 1.0 mm - 1.5 mm.

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