Heavy load engineering tire belt stress dispersion structure and method of manufacturing the same

Abstract

The application relates to the technical field of tire manufacturing, and specifically discloses a heavy-load engineering tire belt stress dispersion structure and a preparation method thereof. The structure comprises, from inside to outside along the radial direction of the tire, an inner liner, a body ply, a shoulder pad component, a belt assembly and a tread rubber, the belt assembly is formed by sequentially stacking a transition belt, a main working belt, a secondary working belt and a hydrophobic belt, and further comprises an isolated rubber with a turning point jaw structure, which clamps the axial two ends of the main working belt in two parts, and the turning point jaws are respectively connected to the corresponding belt end to be engaged. The preparation method comprises component pre-preparation, belt end laser correction, differential lamination, green tire forming and vulcanization shaping, and the isolated rubber is prepared by using a wind cooling process matched with a convex rib supporting shaping process. The application can disperse the stress of the belt end, gently change the belt trend, reduce the heat generation of the tire shoulder, reduce the risk of delamination and cracking, and prolong the service life of the heavy-load engineering tire.

Description

Technical Field

[0001] This application relates to the field of tire manufacturing technology, and more specifically, to a stress dispersion structure for the belt layer of a heavy-duty engineering tire and its preparation method. Background Technology

[0002] Heavy-duty engineering tires are widely used in heavy-duty operations such as mining and construction. The belt layer is the core load-bearing structure of the tire, bearing most of the load and torque during tire operation. Its structural stability directly determines the tire's service life and operational safety. Under high-load cyclic action, the ends of the belt layer are the areas with the highest stress concentration inside the tire and are also the most prone to early failure. Especially on unpaved roads such as mines and construction sites, tires are subjected to frequent impacts and alternating loads, further exacerbating the stress concentration problem at the ends of the belt layer, which can easily lead to early failure, causing equipment downtime and economic losses. Therefore, optimizing the stress distribution at the ends of the belt layer is a key direction for improving the overall performance of heavy-duty engineering tires.

[0003] Most conventional heavy-duty engineering tires employ a four-layer belt structure. The ends of the steel cords in the secondary working belt layer are prone to sharp linear stress concentrations. The belt layer also exhibits a steeper bending trend at its ends, leading to a significant increase in interlayer shear force and consequently, excessive heat generation at the tire shoulder. Existing solutions often involve simply increasing the thickness of the interlayer rubber or using overlapping release rubber, which fails to fundamentally alter the stress transmission path. This results in interlayer slippage, delamination, and hollow areas, ultimately causing premature delamination and cracking at the tire shoulder, making it difficult to meet the practical requirements for long-term stable operation under heavy loads. Summary of the Invention

[0004] To address the problem of stress concentration at the end of the belt layer in existing heavy-duty engineering tires, which leads to premature delamination and cracking of the tire shoulder, this application provides a stress dispersion structure for the belt layer of heavy-duty engineering tires and its preparation method.

[0005] In a first aspect, this application provides a stress dispersion structure for the belt layer of a heavy-duty engineering tire, employing the following technical solution: A stress-dispersing structure for the belt layer of a heavy-duty engineering tire, comprising, in sequence from the inside to the outside along the radial direction of the tire, an inner liner, a carcass ply, a shoulder pad rubber component, a belt layer assembly, and a tread rubber. The belt layer assembly consists of a transition belt layer, a main working belt layer, a secondary working belt layer, and a hydrophobic belt layer stacked from the radial inside to the radial outside. The stress dispersion structure also includes an isolation adhesive, which has an axially inner flat sidewall and an axially outer irregular sidewall. The irregular sidewall has an outwardly protruding inflection point tooth structure in the region corresponding to the end of the belt layer. The isolation adhesive includes a lower isolation adhesive and an upper isolation adhesive. The lower isolation adhesive and the upper isolation adhesive are sandwiched together to cover both ends of the main working belt layer. The flat sidewall of the lower isolation adhesive is attached to the radially lower end face of the endpoint of the main working belt layer, and its axially outer inflection point is in a butt-engaged state with the axial end of the transition belt layer. The flat sidewall of the upper isolation adhesive is attached to the radially upper end face of the endpoint of the main working belt layer, and its axially outer inflection point is in a butt-engaged state with the axial end of the secondary working belt layer.

[0006] By adopting the above technical solution, the upper and lower clamping isolation rubber is filled on both sides of the axial end of the steel cord of the main working belt layer. This effectively fills the gap between the ends of the belt layer, increases the thickness of the clamping rubber in the end area, and the lower isolation rubber supports the main working belt layer to prevent it from collapsing under heavy load. It also smooths the sharp bending trend of the belt layer at the end and evenly distributes the linear stress originally concentrated at the end of the steel cord to the surrounding rubber matrix. At the same time, the end face of the inflection point teeth and the corresponding belt layer end are engaged and matched, replacing the traditional overlapping structure. This eliminates the gap of the overlapping step and blocks the slip path caused by interlayer shear force during tire operation, ensuring that stress can be smoothly and continuously transferred between adjacent belt layers through the isolation rubber.

[0007] Preferably, the shoulder pad adhesive component includes a main body and a low-hardness transition portion covering the lower side isolation adhesive bonding contact area, wherein the Shore A hardness of the low-hardness transition portion is 3 to 8 degrees lower than that of the main body.

[0008] By adopting the above technical solution, a transition section with lower hardness is set in the contact area between the shoulder pad adhesive and the lower isolation adhesive. This avoids the sudden hardness change caused by direct contact between the high-hardness shoulder pad adhesive and the relatively soft isolation adhesive, buffers the interlayer shear stress at the interface under heavy load conditions, and allows the stress to be gradually transferred, preventing the formation of sharp stress concentration points at the interface. This improves the bonding stability between the two and prevents interface debonding after long-term operation. The shoulder pad adhesive component is manufactured in one piece using a twin-screw co-extrusion process, and the two adhesive materials are naturally fused in the die head flow channel without obvious layering interface.

[0009] Preferably, the inflection point tooth structure is composed of two intersecting inclined surfaces on the irregular sidewall of the isolation adhesive, and the included angle between the two inclined surfaces is the inflection point tooth angle. The angle tolerance of the inflection point tooth structure is ±1.0° to ±1.5°.

[0010] By adopting the above technical solution, the inflection point tooth is designed as a structure of two intersecting inclined surfaces, which can form a complete surface contact with the vertical end face of the belt layer end, increasing the contact area and reducing the pressure per unit area. At the same time, the angle tolerance of the inflection point tooth is strictly controlled to ensure the fitting accuracy between the inclined surface of the tooth and the end face of the belt layer end, avoiding local line contact or point contact caused by angle deviation, and ensuring that the mating structure can effectively transfer stress.

[0011] Preferably, in the vulcanized state after bonding, the bonding gap between the inflection point of the isolation adhesive and the end of the auxiliary working belt layer or the end of the transition belt layer does not exceed 0.3 mm.

[0012] By adopting the above technical solution, the bonding gap between the inflection point of the isolation rubber and the end of the auxiliary working belt layer or the end of the transition belt layer after vulcanization is limited to within 0.3mm. This effectively prevents residual air in the gap from expanding and forming closed bubble defects under the high temperature of vulcanization. At the same time, it ensures that the isolation rubber and the belt layer coating achieve full contact and fusion during the vulcanization process, promotes the mutual diffusion of rubber molecular chains and chemical cross-linking reaction, and significantly improves the interfacial bonding strength and structural integrity.

[0013] Secondly, this application provides a method for preparing a stress dispersion structure for the belt layer of a heavy-duty engineering tire, employing the following technical solution: A method for preparing a stress dispersion structure for the belt layer of a heavy-duty engineering tire includes the following steps: S1. Prefabricated components: Provide tire manufacturing inner liner, carcass ply, shoulder pad rubber components, belt ply assembly, tread rubber, and extruded, irregularly shaped cross-section isolation rubber components with inflection point tooth structure. S2. End Precision Correction: A laser positioning device is used to pre-correct the axial ends of the hydrophobic belt layer, the secondary working belt layer, the main working belt layer and the first transition belt layer, control the straightness tolerance of the belt layer ends, and mark the positioning cursor reference line after the correction is qualified. S3, Carcass Ply Bonding: Bond the carcass ply to the radial outer side of the inner liner, and attach shoulder pad rubber components to the corresponding area of ​​the tire shoulder; S4, Bottom belt layer bonding: The transition belt layer is bonded to the radially outer side of the shoulder pad rubber component; S5. Lower side reverse bonding positioning: With the flat side wall of the lower isolation adhesive facing upward, the inflection point of its irregular side wall is placed at the end of the first transition belt layer using the reverse bonding method, so that the lower isolation adhesive is bonded to the radial upper side of the end point of the first transition belt layer. S6, Intermediate belt layer bonding: The main working belt layer is bonded to the radially outer side of the flat side wall of the lower isolation adhesive, so that the radially lower side of the endpoint of the main working belt layer is bonded to the lower isolation adhesive. S7. Top Side Positive Positioning: With the flat sidewall of the top isolation adhesive facing down, and using the bonding positioning cursor reference line marked in step S2 as a reference, the cursor reference line corresponds to the width boundary of the sub-working belt layer. The inflection point of its irregular sidewall is positioned radially above the end of the main working belt layer using the positive bonding method, ensuring that the inflection point fits tightly with the end of the sub-working belt layer to be bonded subsequently. S8. Top layer bonding: Bond the sub-working belt layer and the hydrophobic belt layer in sequence, so that the radial lower side of the end of the sub-working belt layer is engaged with the inflection point of the upper isolation adhesive. S9. Tread laying and forming: Tread rubber is laid on the radial outer side of the hydrophobic belt layer and the isolation rubber to form a green tire blank; S10. Vulcanization and shaping treatment: The green tire blank obtained in step S9 is placed in a vulcanization mold for vulcanization treatment to obtain the finished tire for heavy-duty engineering.

[0014] By adopting the above technical solution, a laser positioning and correction process is introduced before each belt layer bonding process to pre-correct the position of the belt layer end, eliminating the straightness error of the end caused by cutting deviation or conveying offset, and providing a unified benchmark reference for the accurate bonding of the subsequent isolation adhesive. At the same time, in view of the difference in installation orientation between the upper and lower isolation adhesives, different bonding methods of positive bonding and reverse bonding are adopted respectively. The upper isolation adhesive increases the adhesive thickness between the endpoints of the main working belt layer and the secondary working belt layer, ensuring that the inflection point teeth can be accurately aligned and engaged with the corresponding belt layer end face, thereby ensuring the forming accuracy and functional realization of the stress dispersion structure from the process level.

[0015] Preferably, in step S1, the preparation of the isolation adhesive component specifically includes: S1.1, Extrusion shaping: The isolation rubber compound is extruded through a shaped die plate to obtain a continuous rubber strip with a preliminary inflection point tooth profile; S1.2 Shaping and Cooling: The continuous adhesive strip obtained in step S1.1 is passed through a shaping channel under wind conditions. The inner wall of the shaping channel has a convex ridge support structure corresponding to the inflection point teeth of the isolation adhesive. The cooling air temperature is controlled between 15℃ and 25℃, and the wind speed is controlled between 3m / s and 8m / s. S1.3 Slitting and collecting: Cut the continuous rubber strip after shaping and cooling into preset lengths to obtain the finished isolation rubber parts.

[0016] By adopting the above technical solution, a continuous adhesive strip with a complete inflection point tooth profile is pressed out in one go using a customized irregular-shaped die plate, ensuring the consistency of the cross-sectional shape of the isolation adhesive; pure wind cooling is used instead of traditional water tank cooling, avoiding the problem of reduced adhesion and hardening caused by water on the adhesive surface, while eliminating the need for subsequent drying process, preserving the original activity of the adhesive surface, and improving the interfacial bonding strength in the subsequent bonding process.

[0017] Preferably, the convex ridge support structure is used to apply continuous shape constraint to the inflection point of the isolation adhesive, ensuring that the inflection point angle tolerance is ±1.0° to ±1.5° after cooling and shrinkage.

[0018] By adopting the above technical solution, during the cooling and shrinking process of the adhesive strip, the convex support structure fits the two inclined surfaces of the support inflection point tooth throughout the entire process, applying a continuous and uniform external force constraint to the tooth area, offsetting the internal stress deformation caused by the cooling and shrinking of the adhesive, preventing defects such as warping, angle reduction or expansion of the inflection point tooth, and ensuring that the shape accuracy of the isolation adhesive meets the subsequent bonding requirements.

[0019] Preferably, in step S1, the thickness of the low-hardness transition portion of the shoulder pad adhesive component is 0.8 mm to 2.5 mm, and a Shore A hardness gradient transition region is formed between the low-hardness transition portion and the main body portion, wherein the width of the hardness gradient transition region is 3 mm to 8 mm.

[0020] By adopting the above technical solution, controlling the thickness of the low hardness transition section and the width of the hardness gradient transition region, a continuous and smooth hardness change curve can be formed, avoiding stress concentration caused by sudden changes in local hardness. The hardness gradient transition region is formed by the natural fusion of the two rubber materials during co-extrusion, without obvious delamination interface, thus avoiding the delamination interface becoming a source of stress concentration and further optimizing the stress transmission path of the shoulder pad rubber area.

[0021] Preferably, in steps S5 and S7, the inflection point tooth area of ​​the isolation adhesive is preheated before bonding; after bonding, the bonding area is rolled.

[0022] By adopting the above technical solution, only the inflection point tooth area is preheated locally before bonding to avoid deformation of the release adhesive caused by overall preheating. At the same time, the surface activity and initial tack of the adhesive in this area are improved, so that the release adhesive can be quickly and firmly bonded to the end of the belt layer. After bonding, the bonding area is rolled at a uniform speed to remove the tiny air bubbles remaining between the bonding surfaces, so that the adhesives can fully contact each other and improve the tightness of the interface bonding.

[0023] Preferably, in step S10, the vulcanization treatment is carried out at a temperature of 140°C to 160°C, a pressure of 1.8 MPa to 2.5 MPa, and a time of 90 minutes to 130 minutes.

[0024] By adopting the above technical solutions and controlling the temperature, pressure and time parameters of the vulcanization process, the rubber molecular chains inside each rubber component can be fully cross-linked to form a stable three-dimensional network structure, ensuring the overall mechanical properties and structural stability of the tire. The vulcanization pressure can ensure that the rubber compound fully fills the mold cavity, while promoting the diffusion and cross-linking of molecular chains between different rubber components. The vulcanization time and temperature are matched to ensure that the rubber compound is fully vulcanized and that over-vulcanization does not occur.

[0025] In summary, this application has the following beneficial effects: 1. Because this application adopts a structure in which isolation rubber is set on both the upper and lower sides of the end point of the secondary working belt layer, and the isolation rubber is provided with an axially raised inflection point tooth structure, which is in a mating and interlocking state with the axial ends of the upper and lower transition belt layers respectively, the stress at the end point of the belt layer is dispersed from the source, the belt layer trend is smoothed, the heat generation at the tire shoulder is reduced, and the risk of delamination and cracking is reduced.

[0026] 2. In this application, the shoulder pad adhesive is preferably used to set a low hardness transition part, and a continuous and smooth hardness gradient transition area is formed between the low hardness transition part and the main part. This further buffers the stress concentration in the shoulder, avoids the interface stress caused by sudden hardness changes, and improves the bonding stability between the shoulder pad adhesive and the isolation adhesive.

[0027] 3. The method of this application prepares the isolation adhesive by using wind cooling combined with convex ridge support for shaping. The convex ridge support structure applies continuous and uniform shape constraint to the inflection point tooth area, thus achieving the effect of counteracting the cooling shrinkage deformation of the adhesive strip, ensuring the accuracy of the inflection point tooth angle, and preserving the surface activity of the adhesive material.

[0028] 4. The method of this application adopts a differentiated bonding method of bottom reverse bonding plus side front bonding, and preheats the inflection point tooth area before bonding with the isolation adhesive, and rolls the bonding part after bonding. Therefore, it achieves the effect of ensuring accurate alignment between the inflection point tooth and the end of the belt layer, improving the bonding tightness, and expelling interface air. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the shoulder section of the stress dispersion structure of the tire belt layer for heavy-duty engineering provided in this application; Figure 2 This is an enlarged structural schematic diagram of the release adhesive provided in this application; Figure 3 This is a schematic diagram of the bonding state of the stress dispersion structure of the heavy-duty engineering tire belt layer provided in the embodiment of this application during the molding and preparation process; Figure 4 This is a flowchart of a method for preparing a stress dispersion structure for the belt layer of a heavy-duty engineering tire, as provided in this application.

[0030] The components include: 1. Inner liner; 2. Shoulder pad rubber components; 3. Isolation rubber; 4. Tread rubber; A. Hydrophobic belt layer; B. Secondary working belt layer; C. Main working belt layer; D. Transition belt layer; E. Carcass ply. Detailed Implementation

[0031] The present application will be further described in detail below with reference to embodiments and comparative examples. Unless otherwise specified, the experimental methods used below are conventional methods. Unless otherwise specified, the materials, reagents, methods and instruments used are all conventional materials, reagents, methods and instruments in the art, which can be obtained by those skilled in the art through commercial channels or prepared according to literature methods.

[0032] Technical Concept: Heavy-duty engineering tires operate under continuous high load and high torque conditions, and the end region of the belt layer is a structural weak point and a typical failure site. In conventional four-layer belt layer structures, there is a sharp linear stress concentration at the ends of the steel cords in the secondary working belt layer. The belt layer bends steeply at the ends, inducing a sharp increase in interlayer shear force, which leads to a significantly accelerated heat generation rate at the tire shoulder. Existing solutions are mostly limited to simply increasing the thickness of the end-layer rubber or using overlapping release rubber. These methods cannot fundamentally change the stress transmission path, and the preparation of release rubber often relies on traditional water tank cooling processes, resulting in reduced surface activity of the rubber compound, difficulty in effectively controlling bonding accuracy, and easy occurrence of molding defects such as interlayer slippage, interface debonding, and internal voids. Ultimately, this manifests as premature delamination and cracking at the tire shoulder, significantly reducing service life.

[0033] This technical solution addresses the aforementioned problems by simultaneously applying a separating adhesive with a bend-point tooth structure to both sides of the endpoint of the secondary working belt layer. This allows the separating adhesive to form a mating, interlocking fit with the adjacent transition belt layer ends, thereby smoothing the bending trend of the belt layer, uniformly distributing concentrated linear stress to the surrounding rubber matrix, and blocking interlayer slippage paths. At the process level, a wind-cooled separating adhesive preparation method supplemented by convex ridge support ensures the accuracy of the bend-point tooth shape and the surface activity of the rubber compound. Differentiated bonding processes, including reverse bonding on the lower side and forward bonding on the upper side, improve alignment accuracy. Simultaneously, a continuous hardness gradient transition section is constructed in the corresponding area of ​​the shoulder pad adhesive to further buffer interlayer shear stress. The synergistic effect of these structures and processes effectively suppresses heat generation in the tire shoulder, strengthens interfacial bonding strength, and thus significantly extends the service life of heavy-duty engineering tires.

[0034] Preparation Example 1: The preparation method of a shoulder pad rubber component with a low-hardness transition layer is as follows: A main rubber compound and a low-hardness rubber compound are prepared separately. The main rubber compound uses a standard heavy-duty engineering tire shoulder pad rubber base formula, with a Shore A hardness of 65 degrees after mixing. The low-hardness rubber compound is prepared by reducing 8 parts of carbon black N330 and increasing 4 parts of naphthenic oil based on the main rubber compound formula, resulting in a Shore A hardness of 60 degrees after mixing. Both rubber compounds are preheated to 80°C and then simultaneously fed into the two independent barrels of a twin-screw co-extruder. The screw speed for the main rubber compound is controlled at 25 r / min, and the screw speed for the low-hardness rubber compound is controlled at 8 r / min. The co-extruder head temperature is set to 90°C. During extrusion, the two rubber compounds naturally fuse within the die head channel to form a hardness gradient transition area with a width of 5 mm. Simultaneously, the extrusion thickness of the low-hardness transition layer is controlled to be 1.5 mm. After extrusion, the continuous rubber strip is air-cooled to room temperature and then cut to a preset length to obtain the finished shoulder pad rubber component with the low-hardness transition section.

[0035] The stress-dispersing structure of the tire belt layer for heavy-duty engineering includes an inner liner layer 1, a carcass ply layer E, a shoulder pad rubber component 2, a belt layer assembly, and a tread compound 4, arranged sequentially from the inside to the outside along the tire's radial direction. The belt layer assembly consists of a transition belt layer D, a main working belt layer C, a secondary working belt layer B, and a hydrophobic belt layer A, stacked from the radial inside to the radial outside. The stress-dispersing structure also includes a separating rubber 3, which has a flat sidewall on the axially inner side and a shaped sidewall on the axially outer side. The shaped sidewall has an outwardly protruding bend tooth structure in the region corresponding to the end of the belt layer.

[0036] The isolation adhesive 3 includes a lower isolation adhesive and an upper isolation adhesive. The lower isolation adhesive and the upper isolation adhesive are sandwiched together to cover both ends of the main working belt layer C. The flat sidewall of the lower isolation adhesive is attached to the radially lower end face of the endpoint of the main working belt layer C, and its axially outer inflection point is in a butt-engaged state with the axial end of the transition belt layer D. The flat sidewall of the upper isolation adhesive is attached to the radially upper end face of the endpoint of the main working belt layer C, and its axially outer inflection point is in a butt-engaged state with the axial end of the secondary working belt layer B.

[0037] The shoulder pad adhesive component 2 includes a main body and a low-hardness transition section covering the contact area of ​​the lower isolation adhesive. The Shore A hardness of the low-hardness transition section is 3 to 8 degrees lower than that of the main body. The inflection point tooth structure is formed by two intersecting inclined surfaces on the irregular sidewall of the isolation adhesive 3. The included angle between the two inclined surfaces is the inflection point tooth angle, and the angular tolerance of the inflection point tooth structure is ±1.0° to ±1.5°. In the vulcanized state after bonding, the bonding gap between the inflection point tooth of the isolation adhesive 3 and the end of the auxiliary working belt layer B or the end of the transition belt layer D does not exceed 0.3 mm.

[0038] Example 1: This example provides a method for preparing the stress dispersion structure of the belt layer of a heavy-duty engineering tire, including the following steps: S1. Prefabricated components: Provide tire manufacturing inner liner 1, carcass ply E, shoulder pad rubber component 2, belt layer assembly, tread rubber 4, and extruded, irregularly shaped cross-section isolation rubber component 3 with inflection point tooth structure.

[0039] The preparation of the isolation adhesive component 3 specifically includes: S1.1, Extrusion and Shaping: The isolation type rubber 3 compound is extruded through a shaped die plate to obtain a continuous rubber strip with a preliminary inflection point tooth profile.

[0040] S1.2 Shaping and Cooling: The continuous adhesive strip obtained in step S1.1 is passed through a shaping channel under wind conditions. The inner wall of the shaping channel has a convex ridge support structure corresponding to the inflection point teeth of the isolation adhesive 3. The cooling air temperature is controlled at 20℃ and the wind speed is controlled at 5.5m / s.

[0041] Among them, the convex ridge support structure fits the two inclined surfaces of the support inflection point tooth throughout the entire process, and applies continuous and uniform shape constraint to the inflection point tooth of the isolation adhesive 3, which counteracts the shrinkage deformation during the cooling process of the adhesive strip and ensures that the inflection point tooth angle tolerance is ±1.25° after cooling and shrinkage.

[0042] S1.3, Slitting and Collecting: Cut the continuous rubber strip after shaping and cooling to a preset length to obtain the finished part of the isolation type adhesive 3.

[0043] The shoulder pad rubber component 2 is manufactured in one piece using a twin-screw co-extrusion process, where the two rubber materials are naturally fused within the die head flow channel without any obvious layering interface. The thickness of the low-hardness transition portion of the shoulder pad rubber component 2 is 1.65 mm, and a continuous and smooth Shore A hardness gradient transition region is formed between the low-hardness transition portion and the main body, with a width of 5.5 mm. The Shore A hardness of the main body of the shoulder pad rubber component 2 is 65 degrees, and the Shore A hardness of the low-hardness transition portion is 60 degrees.

[0044] S2. End Precision Correction: A laser positioning device is used to pre-correct the axial ends of the hydrophobic belt layer A, the secondary working belt layer B, the main working belt layer C, and the transition belt layer D, to control the straightness tolerance of the belt layer ends, and mark the positioning cursor reference line after the correction is qualified.

[0045] The laser positioning device uses an industrial laser scribing instrument with an accuracy of 0.1mm to scan and correct the position of the belt layer end segment by segment. The straightness tolerance of the belt layer end is controlled within 0.5mm to ensure that the inflection point of the subsequent isolation adhesive is accurately connected to the belt layer end.

[0046] S3, Carcass Ply Bonding: Bond the carcass ply E to the radial outer side of the inner liner 1, and attach the shoulder pad rubber component 2 to the corresponding area of ​​the tire shoulder.

[0047] S4, Bottom belt layer bonding: The transition belt layer D is laminated on the radially outer side of the shoulder pad adhesive component 2.

[0048] S5. Lower side reverse bonding positioning: With the flat sidewall of the lower isolation adhesive facing upward, the inflection point of its irregular sidewall is positioned at the end of the transition belt layer D using the reverse bonding method, so that the lower isolation adhesive is bonded to the radial upper side of the end point of the transition belt layer D.

[0049] Before bonding the isolation adhesive 3, its inflection point tooth area is preheated with infrared to improve the surface activity and adhesion of the adhesive. After bonding, the bonding area is rolled at a uniform speed to expel air between the bonding surfaces. The preheating uses an infrared preheater with a wavelength of 8-14μm, and the rolling uses a 100mm diameter Shore A type rubber roller with a hardness of 60 degrees, and the rolling is performed twice.

[0050] S6. Intermediate belt layer bonding: The main working belt layer C is bonded to the radially outer side of the flat sidewall of the lower isolation adhesive, so that the radially lower side of the endpoint of the main working belt layer C is bonded to the lower isolation adhesive.

[0051] S7. Top Side Positive Positioning: With the flat sidewall of the top isolation adhesive facing down, and using the bonding positioning cursor reference line marked in step S2 as a reference, the cursor reference line corresponds to the width boundary of the sub-working belt layer B. Using the positive bonding method, position the inflection point of its irregular sidewall on the radial upper side of the end of the main working belt layer C, ensuring that the inflection point fits tightly with the end of the sub-working belt layer B to be bonded subsequently.

[0052] Before bonding the isolation adhesive 3, its inflection point tooth area is preheated with infrared to improve the surface activity and adhesion of the adhesive. After bonding, the bonding area is rolled at a uniform speed to expel air between the bonding surfaces. The preheating uses an infrared preheater with a wavelength of 8-14μm, and the rolling uses a 100mm diameter Shore A type rubber roller with a hardness of 60 degrees, and the rolling is performed twice.

[0053] S8. Top layer bonding: Bond the sub-working belt layer B and the hydrophobic belt layer A in sequence, so that the radially lower side of the end of the sub-working belt layer B is engaged with the inflection point of the upper isolation adhesive.

[0054] S9. Tread laying and forming: Tread rubber 4 is laid on the radial outer side of the hydrophobic belt layer A and the isolation rubber 3 to form a green tire blank.

[0055] S10. Vulcanization and shaping treatment: The green tire blank obtained in step S9 is placed in a vulcanization mold for vulcanization treatment to obtain the finished tire for heavy-duty engineering.

[0056] The vulcanization process involves a temperature of 150℃, a pressure of 2.15MPa, and a time of 110 minutes, which allows for the formation of a stable and tight cross-linked molecular chain structure between the various rubber components.

[0057] Example 2: This example provides a method for preparing the stress dispersion structure of the belt layer of a heavy-duty engineering tire, including the following steps: S1. Prefabricated components: Provide tire manufacturing inner liner 1, carcass ply E, shoulder pad rubber component 2, belt layer assembly, tread rubber 4, and extruded, irregularly shaped cross-section isolation rubber component 3 with inflection point tooth structure.

[0058] The preparation of the isolation adhesive component 3 specifically includes: S1.1, Extrusion and Shaping: The isolation type rubber 3 compound is extruded through a shaped die plate to obtain a continuous rubber strip with a preliminary inflection point tooth profile.

[0059] S1.2 Shaping and Cooling: The continuous adhesive strip obtained in step S1.1 is passed through a shaping channel under wind conditions. The inner wall of the shaping channel has a convex ridge support structure corresponding to the inflection point teeth of the isolation adhesive 3. The cooling air temperature is controlled at 15℃ and the wind speed is controlled at 3m / s.

[0060] Among them, the convex ridge support structure fits the two inclined surfaces of the support inflection point tooth throughout the entire process, and applies continuous and uniform shape constraint to the inflection point tooth of the isolation adhesive 3, which counteracts the shrinkage deformation during the cooling process of the adhesive strip and ensures that the inflection point tooth angle tolerance is ±1.0° after cooling and shrinkage.

[0061] S1.3, Slitting and Collecting: Cut the continuous rubber strip after shaping and cooling to a preset length to obtain the finished part of the isolation type adhesive 3.

[0062] The shoulder pad rubber component 2 is manufactured in one piece using a twin-screw co-extrusion process, where the two rubber materials are naturally fused within the die head flow channel without any obvious layering interface. The thickness of the low-hardness transition portion of the shoulder pad rubber component 2 is 0.8 mm, and a continuous and smooth Shore A hardness gradient transition region is formed between the low-hardness transition portion and the main body, with a width of 3 mm. The Shore A hardness of the main body of the shoulder pad rubber component 2 is 65 degrees, and the Shore A hardness of the low-hardness transition portion is 62 degrees.

[0063] S2. End Precision Correction: A laser positioning device is used to pre-correct the axial ends of the hydrophobic belt layer A, the secondary working belt layer B, the main working belt layer C, and the transition belt layer D, to control the straightness tolerance of the belt layer ends, and mark the positioning cursor reference line after the correction is qualified.

[0064] The laser positioning device uses an industrial laser scribing instrument with an accuracy of 0.1mm to scan and correct the position of the belt layer end segment by segment. The straightness tolerance of the belt layer end is controlled within 0.5mm to ensure that the inflection point of the subsequent isolation adhesive is accurately connected to the belt layer end.

[0065] S3, Carcass Ply Bonding: Bond the carcass ply E to the radial outer side of the inner liner 1, and attach the shoulder pad rubber component 2 to the corresponding area of ​​the tire shoulder.

[0066] S4, Bottom belt layer bonding: The transition belt layer D is laminated on the radially outer side of the shoulder pad adhesive component 2.

[0067] S5. Lower side reverse bonding positioning: With the flat sidewall of the lower isolation adhesive facing upward, the inflection point of its irregular sidewall is positioned at the end of the transition belt layer D using the reverse bonding method, so that the lower isolation adhesive is bonded to the radial upper side of the end point of the transition belt layer D.

[0068] Before bonding the isolation adhesive 3, its inflection point tooth area is preheated with infrared to improve the surface activity and adhesion of the adhesive. After bonding, the bonding area is rolled at a uniform speed to expel air between the bonding surfaces. The preheating uses an infrared preheater with a wavelength of 8-14μm, and the rolling uses a 100mm diameter Shore A type rubber roller with a hardness of 60 degrees, and the rolling is performed twice.

[0069] S6. Intermediate belt layer bonding: The main working belt layer C is bonded to the radially outer side of the flat sidewall of the lower isolation adhesive, so that the radially lower side of the endpoint of the main working belt layer C is bonded to the lower isolation adhesive.

[0070] S7. Top Side Positive Positioning: With the flat sidewall of the top isolation adhesive facing down, and using the bonding positioning cursor reference line marked in step S2 as a reference, the cursor reference line corresponds to the width boundary of the sub-working belt layer B. Using the positive bonding method, position the inflection point of its irregular sidewall on the radial upper side of the end of the main working belt layer C, ensuring that the inflection point fits tightly with the end of the sub-working belt layer B to be bonded subsequently.

[0071] Before bonding the isolation adhesive 3, its inflection point tooth area is preheated with infrared to improve the surface activity and adhesion of the adhesive. After bonding, the bonding area is rolled at a uniform speed to expel air between the bonding surfaces. The preheating uses an infrared preheater with a wavelength of 8-14μm, and the rolling uses a 100mm diameter Shore A type rubber roller with a hardness of 60 degrees, and the rolling is performed twice.

[0072] S8. Top layer bonding: Bond the sub-working belt layer B and the hydrophobic belt layer A in sequence, so that the radially lower side of the end of the sub-working belt layer B is engaged with the inflection point of the upper isolation adhesive.

[0073] S9. Tread laying and forming: Tread rubber 4 is laid on the radial outer side of the hydrophobic belt layer A and the isolation rubber 3 to form a green tire blank.

[0074] S10. Vulcanization and shaping treatment: The green tire blank obtained in step S9 is placed in a vulcanization mold for vulcanization treatment to obtain the finished tire for heavy-duty engineering.

[0075] The vulcanization process involves a temperature of 140℃, a pressure of 1.8MPa, and a time of 90 minutes, which allows for the formation of a stable and tight cross-linked molecular chain structure between the various rubber components.

[0076] Example 3: This example provides a method for preparing the stress dispersion structure of the belt layer of a heavy-duty engineering tire, including the following steps: S1. Prefabricated components: Provide tire manufacturing inner liner 1, carcass ply E, shoulder pad rubber component 2, belt layer assembly, tread rubber 4, and extruded, irregularly shaped cross-section isolation rubber component 3 with inflection point tooth structure.

[0077] The preparation of the isolation adhesive component 3 specifically includes: S1.1, Extrusion and Shaping: The isolation type rubber 3 compound is extruded through a shaped die plate to obtain a continuous rubber strip with a preliminary inflection point tooth profile.

[0078] S1.2 Shaping and Cooling: The continuous adhesive strip obtained in step S1.1 is passed through a shaping channel under wind conditions. The inner wall of the shaping channel has a convex ridge support structure corresponding to the inflection point teeth of the isolation adhesive 3. The cooling air temperature is controlled at 25℃ and the wind speed is controlled at 8m / s.

[0079] Among them, the convex ridge support structure fits the two inclined surfaces of the support inflection point tooth throughout the entire process, and applies continuous and uniform shape constraint to the inflection point tooth of the isolation adhesive 3, which counteracts the shrinkage deformation during the cooling process of the adhesive strip and ensures that the inflection point tooth angle tolerance is ±1.5° after cooling and shrinkage.

[0080] S1.3, Slitting and Collecting: Cut the continuous rubber strip after shaping and cooling to a preset length to obtain the finished part of the isolation type adhesive 3.

[0081] The shoulder pad rubber component 2 is manufactured in one piece using a twin-screw co-extrusion process, where the two rubber materials are naturally fused within the die head flow channel without any obvious layering interface. The thickness of the low-hardness transition portion of the shoulder pad rubber component 2 is 2.5 mm, and a continuous and smooth Shore A hardness gradient transition region is formed between the low-hardness transition portion and the main body, with a width of 8 mm. The Shore A hardness of the main body of the shoulder pad rubber component 2 is 65 degrees, and the Shore A hardness of the low-hardness transition portion is 57 degrees.

[0082] S2. End Precision Correction: A laser positioning device is used to pre-correct the axial ends of the hydrophobic belt layer A, the secondary working belt layer B, the main working belt layer C, and the transition belt layer D, to control the straightness tolerance of the belt layer ends, and mark the positioning cursor reference line after the correction is qualified.

[0083] The laser positioning device uses an industrial laser scribing instrument with an accuracy of 0.1mm to scan and correct the position of the belt layer end segment by segment. The straightness tolerance of the belt layer end is controlled within 0.5mm to ensure that the inflection point of the subsequent isolation adhesive is accurately connected to the belt layer end.

[0084] S3, Carcass Ply Bonding: Bond the carcass ply E to the radial outer side of the inner liner 1, and attach the shoulder pad rubber component 2 to the corresponding area of ​​the tire shoulder.

[0085] S4, Bottom belt layer bonding: The transition belt layer D is laminated on the radially outer side of the shoulder pad adhesive component 2.

[0086] S5. Lower side reverse bonding positioning: With the flat sidewall of the lower isolation adhesive facing upward, the inflection point of its irregular sidewall is positioned at the end of the transition belt layer D using the reverse bonding method, so that the lower isolation adhesive is bonded to the radial upper side of the end point of the transition belt layer D.

[0087] Before bonding the isolation adhesive 3, its inflection point tooth area is preheated with infrared to improve the surface activity and adhesion of the adhesive. After bonding, the bonding area is rolled at a uniform speed to expel air between the bonding surfaces. The preheating uses an infrared preheater with a wavelength of 8-14μm, and the rolling uses a 100mm diameter Shore A type rubber roller with a hardness of 60 degrees, and the rolling is performed twice.

[0088] S6. Intermediate belt layer bonding: The main working belt layer C is bonded to the radially outer side of the flat sidewall of the lower isolation adhesive, so that the radially lower side of the endpoint of the main working belt layer C is bonded to the lower isolation adhesive.

[0089] S7. Top Side Positive Positioning: With the flat sidewall of the top isolation adhesive facing down, and using the bonding positioning cursor reference line marked in step S2 as a reference, the cursor reference line corresponds to the width boundary of the sub-working belt layer B. Using the positive bonding method, position the inflection point of its irregular sidewall on the radial upper side of the end of the main working belt layer C, ensuring that the inflection point fits tightly with the end of the sub-working belt layer B to be bonded subsequently.

[0090] Before bonding the isolation adhesive 3, its inflection point tooth area is preheated with infrared to improve the surface activity and adhesion of the adhesive. After bonding, the bonding area is rolled at a uniform speed to expel air between the bonding surfaces. The preheating uses an infrared preheater with a wavelength of 8-14μm, and the rolling uses a 100mm diameter Shore A type rubber roller with a hardness of 60 degrees, and the rolling is performed twice.

[0091] S8. Top layer bonding: Bond the sub-working belt layer B and the hydrophobic belt layer A in sequence, so that the radially lower side of the end of the sub-working belt layer B is engaged with the inflection point of the upper isolation adhesive.

[0092] S9. Tread laying and forming: Tread rubber 4 is laid on the radial outer side of the hydrophobic belt layer A and the isolation rubber 3 to form a green tire blank.

[0093] S10. Vulcanization and shaping treatment: The green tire blank obtained in step S9 is placed in a vulcanization mold for vulcanization treatment to obtain the finished tire for heavy-duty engineering.

[0094] The vulcanization process involves a temperature of 160℃, a pressure of 2.5MPa, and a time of 130 minutes, which allows for the formation of a stable and tight cross-linked molecular chain structure between the various rubber components.

[0095] Comparative Example 1: The only difference between this comparative example and Example 1 is that it adopts the conventional four-layer belt structure and preparation method of heavy-duty engineering tires with existing technology, without isolation rubber components, without inflection point tooth structure, the isolation rubber is prepared by the traditional water tank cooling method, and the shoulder pad rubber is a homogeneous rubber material with a single Shore A hardness. The overall specifications, dimensions and general raw materials used in the tire are exactly the same as those in Example 1.

[0096] Comparative Example 2: The only difference between this comparative example and Example 1 is that the isolation adhesive component is completely removed, the bonding operations related to the isolation adhesive in steps S5 and S7 are cancelled, and the belt layer assembly is directly laminated in the order of transition belt layer D, main working belt layer C, secondary working belt layer B, and hydrophobic belt layer A.

[0097] Comparative Example 3: The only difference between this comparative example and Example 1 is that the isolation adhesive uses a homogeneous adhesive strip with a rectangular cross-section and no axially protruding inflection point tooth structure. The rest of the bonding positions and all process parameters are exactly the same as those in Example 1.

[0098] Comparative Example 4: The only difference between this comparative example and Example 1 is that in the preparation of the isolation adhesive component, step S1.2 uses the traditional water tank cooling method instead of air cooling, and the shaping channel with the inner wall ridge support structure is not used. All other structures and process parameters are exactly the same as in Example 1.

[0099] Comparative Example 5: The only difference between this comparative example and Example 1 is that the lower isolation adhesive uses the same positive application method as the upper isolation adhesive, and does not use the reverse application method. All other structures and process parameters are exactly the same as those in Example 1.

[0100] I. Steady-state heat generation test of tire shoulder: Referring to GB / T4501-2016 "Test Method for Durability of Truck Tires", a tire drum tester was used to conduct steady-state heat generation tests on the tires prepared in Examples 1-3 and Comparative Examples 1-5. All tires were tested under the same inflation pressure, rated load and rated speed conditions. The ambient temperature was controlled at 25℃±2℃ and the relative humidity was controlled at 50%±10%. Before the test, the tires were placed in the test environment for more than 24 hours to reach thermal equilibrium. During the test, the tires were mounted on the rim of the tester and adjusted to the specified inflation pressure and load. The tester was started and the tires were run continuously at the rated speed for 2 hours. During the operation, an infrared thermal imager was used to collect temperature distribution images of the tire shoulder every 15 minutes. The highest temperature of the end area of ​​the belt layer on the shoulder of each tire was recorded after 2 hours of operation. At the same time, the temperature of the center area of ​​the tire tread was recorded as a reference to compare the differences in shoulder heat generation among different tires.

[0101] II. Interfacial Shear Strength Test of Belt Layer: Referring to GB / T13936-2014 "Determination of Adhesion Strength between Vulcanized Rubber and Metal - Tensile Method", a universal testing machine was used to test the interfacial shear strength of the tires prepared in Examples 1-3 and Comparative Examples 1-5. A standard specimen with dimensions of 50mm×20mm×10mm was cut from the shoulder belt layer area of ​​each tire. The specimen included the interface between the isolation rubber and the rubber coating of the adjacent belt layer. The two ends of the specimen were clamped in the upper and lower clamps of the universal testing machine. The clamp spacing was adjusted to make the specimen in a naturally straight state. The shear test was carried out at a tensile speed of 50mm / min until the specimen broke. The maximum shear force of each specimen was recorded, and the interfacial shear strength was calculated. Five parallel specimens were prepared for each tire, and the average value was taken as the final test result. At the same time, the fracture mode of each specimen was observed and recorded to distinguish between interfacial fracture and rubber body fracture.

[0102] III. Accelerated Durability Testing of Tires: Referring to GB / T4501-2016 "Test Method for Durability of Truck Tires", the tires prepared in Examples 1-3 and Comparative Examples 1-5 were tested using a tire drum tester. All tires were tested under the same inflation pressure and environmental conditions. The test was conducted in three stages: the first stage was 47 hours of continuous operation at rated load and rated speed; the second stage was to increase the load to 110% of the rated load and run continuously at the same speed for 6 hours; and the third stage was to increase the load to 120% of the rated load and run continuously at the same speed until tire failure. The total running time and total mileage of each tire from the start of the test to failure were recorded. The failure mode of each tire was also recorded in detail, including shoulder delamination, hollowing, cracking, and tread chipping, etc. The differences in durability performance between different tires were compared.

[0103] IV. Microstructural Analysis of Failed Tires: Referring to GB / T16594-2008 "General Rules for Scanning Electron Microscopy Measurement Methods of Micrometer-Scale Lengths", a scanning electron microscope was used to analyze the microstructure of the belt layer endpoint region of the failed tires in Examples 1-3 and Comparative Examples 1-5. A 10mm×10mm×5mm sample was cut from the crack origin of each failed tire. After the sample surface was sputter-coated with gold, it was placed in the sample chamber of the scanning electron microscope. The interface morphology, crack origin location and propagation path of the belt layer endpoint were observed at different magnifications. At the same time, the cross-linking state of the rubber molecular chains and the interfacial bonding were observed. The differences in microstructure among different tires were compared to analyze the root cause of tire failure and verify the inhibitory effect of the technical solution of this application on stress concentration and crack propagation.

[0104]

[0105] The main failure modes of each sample are described below: Example 1: After the test, the tire only showed slight tread wear, and no delamination, hollowing or cracking was observed in the tire shoulder area. The end of the belt layer was tightly bonded to the isolation rubber, and there were no traces of interface separation.

[0106] Example 2: After the test, the tire showed slight tread wear, which was slightly higher than that in Example 1. The tire shoulder area remained intact, with no delamination, hollowing or cracking defects. The interlocking state between the isolation rubber and the belt layer end was good.

[0107] Example 3: After the test, the tire showed slight tread wear, which was similar to that in Example 2. There was no structural damage in the tire shoulder area, the stress dispersion effect at the end of the belt layer was stable, and no crack origin was found.

[0108] Comparative Example 1: When the test reached 120.0h, a large area of ​​delamination and hollowing occurred on the tire shoulder. Multiple longitudinal cracks appeared at the end of the belt layer and spread rapidly, eventually causing the entire tire shoulder to crack and fail, making it impossible to continue operating.

[0109] Comparative Example 2: When the test was conducted for 123.7 hours, local delamination occurred on the tire shoulder, and obvious longitudinal cracks occurred at the end of the secondary working belt layer due to stress concentration. The cracks extended along the axial direction of the belt layer, and irregular pieces of the tread appeared.

[0110] Comparative Example 3: After 131.6 hours of testing, interfacial slippage occurred between the rectangular cross-section isolation adhesive and the end of the belt layer, local delamination occurred at the bonding area, and micro-cracks appeared at the end of the belt layer and gradually expanded.

[0111] Comparative Example 4: After 128.3 hours of testing, interfacial debonding occurred between the isolation adhesive and the belt layer adhesive, resulting in multiple hollow areas at the bonding site. The hollow areas gradually expanded and caused cracking of the surrounding rubber.

[0112] Comparative Example 5: After 133.1 hours of testing, the lower isolation adhesive caused local stress concentration due to misalignment, resulting in a transverse crack below the end point of the secondary working belt layer. After the crack propagated, it caused a small-scale shoulder delamination.

[0113] As can be seen from Examples 1-3 and Comparative Example 1, and Table 1, the stress dispersion structure and supporting preparation method of the belt layer proposed in this application can effectively alleviate the stress concentration problem at the end of the belt layer of heavy-duty engineering tires, reduce shoulder heat generation during tire operation, improve the interfacial bonding strength of the belt layer, and thus significantly extend the service life of the tire.

[0114] As can be seen from Examples 1-3 and Comparative Example 2, and Table 1, simultaneously setting isolation rubber on both the upper and lower sides of the endpoint of the secondary working belt layer is the core means of dispersing the stress at the endpoint of the belt layer. The lack of isolation rubber will lead to a sharp concentration of stress at the endpoint of the belt layer, a significant increase in heat generation at the tire shoulder, a decrease in interfacial bonding strength, and ultimately a significant shortening of the tire's durability.

[0115] As can be seen from Examples 1-3 and Comparative Example 3, and Table 1, the inflection point tooth structure of the isolation adhesive can form a tight mating and interlocking state with the end of the belt layer, eliminating the bonding gap, preventing interlayer slippage, effectively improving the interfacial bonding strength, and thus improving the shoulder heat generation and durability of the tire.

[0116] As can be seen from Examples 1-3 and Comparative Example 4, and Table 1, the method of preparing the isolation adhesive by using wind cooling combined with convex ridge support for shaping can ensure the surface activity and shape accuracy of the inflection point teeth of the isolation adhesive, improve the vulcanization crosslinking effect of the isolation adhesive and the belt layer coating, enhance the interfacial bonding force, and avoid interfacial debonding and hollow defects after vulcanization.

[0117] As can be seen from Examples 1-3 and Comparative Example 5, and Table 1, the reverse application of the lower isolation adhesive can ensure the precise alignment of the inflection point teeth with the end of the main working belt layer, avoiding local stress concentration caused by alignment deviation, thereby improving the overall performance and service life of the tire.

[0118] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A stress dispersion structure for the belt layer of a heavy-duty engineering tire, comprising an inner liner (1), a carcass ply (E), a shoulder pad rubber component (2), a belt layer assembly, and a tread rubber (4) arranged sequentially from the inside to the outside along the radial direction of the tire, characterized in that: The belt layer assembly consists of a transition belt layer (D), a main working belt layer (C), a secondary working belt layer (B), and a hydrophobic belt layer (A) stacked from the radial inside to the radial outside. The stress dispersion structure also includes an isolation adhesive (3), which has an axially inner flat sidewall and an axially outer irregular sidewall. The irregular sidewall has an outwardly protruding inflection point tooth structure in the region corresponding to the end of the belt layer. The isolation adhesive (3) includes a lower isolation adhesive and an upper isolation adhesive. The lower isolation adhesive and the upper isolation adhesive are sandwiched together to cover the axial ends of the main working belt layer (C). The flat sidewall of the lower isolation adhesive is attached to the radially lower end face of the endpoint of the main working belt layer (C), and its axially outer inflection point is engaged with the axial end of the transition belt layer (D). The flat sidewall of the upper isolation adhesive is attached to the radially upper end face of the endpoint of the main working belt layer (C), and its axially outer inflection point is engaged with the axial end of the secondary working belt layer (B).

2. The stress dispersion structure of the belt layer of a heavy-duty engineering tire according to claim 1, characterized in that: The shoulder pad adhesive component (2) includes a main body and a low-hardness transition portion covering the lower side isolation adhesive bonding contact area. The Shore A hardness of the low-hardness transition portion is 3 to 8 degrees lower than that of the main body.

3. The stress dispersion structure of the belt layer of a heavy-duty engineering tire according to claim 1, characterized in that: The inflection point tooth structure is composed of two intersecting inclined surfaces on the irregular sidewall of the isolation adhesive (3). The included angle between the two inclined surfaces is the inflection point tooth angle. The angle tolerance of the inflection point tooth structure is ±1.0° to ±1.5°.

4. The stress dispersion structure of the belt layer of a heavy-duty engineering tire according to claim 1, characterized in that: The bonding gap between the inflection point of the isolation adhesive (3) and the end of the auxiliary working belt layer (B) or the end of the transition belt layer (D) in the vulcanized state after bonding does not exceed 0.3 mm.

5. A method for preparing a stress dispersion structure for the belt layer of a heavy-duty engineering tire, characterized in that, A stress dispersion structure for the belt layer of a heavy-duty engineering tire as described in any one of claims 1-4 includes the following steps: S1. Prefabricated components: Provide tire manufacturing inner liner (1), carcass ply (E), shoulder pad rubber component (2), belt ply assembly, tread rubber (4), and extruded, irregular cross-section isolation rubber (3) component with inflection point tooth structure; S2. End Precision Correction: A laser positioning device is used to pre-correct the axial ends of the hydrophobic belt layer (A), the secondary working belt layer (B), the main working belt layer (C), and the first transition belt layer (D) to control the straightness tolerance of the belt layer ends. After the correction is qualified, the positioning cursor reference line is marked and attached. S3, Carcass layer bonding: The carcass ply (E) is bonded to the radial outer side of the inner liner (1), and the shoulder pad rubber component (2) is applied to the corresponding area of ​​the tire shoulder. S4, Bottom belt layer bonding: The transition belt layer (D) is sequentially laminated on the radial outer side of the shoulder pad adhesive component (2); S5. Lower side reverse bonding positioning: With the flat side wall of the lower isolation adhesive facing upward, the inflection point of its irregular side wall is placed at the end of the first transition belt layer (D) using the reverse bonding method, so that the lower isolation adhesive is bonded to the radial upper side of the end point of the first transition belt layer (D). S6, intermediate belt layer bonding: the main working belt layer (C) is bonded to the radially outer side of the flat side wall of the lower isolation adhesive, so that the radially lower side of the endpoint of the main working belt layer (C) is bonded to the lower isolation adhesive; S7. Top Side Positive Positioning: With the flat sidewall of the top isolation adhesive facing downwards, and with the bonding positioning cursor reference line marked in step S2 as a reference, the cursor reference line corresponds to the width boundary of the sub-working belt layer (B). The inflection point of its irregular sidewall is positioned radially upwards at the end of the main working belt layer (C) using the positive bonding method, ensuring that the inflection point fits tightly with the end of the sub-working belt layer (B) to be bonded subsequently. S8. Top layer bonding: Bond the sub-working belt layer (B) and the hydrophobic belt layer (A) in sequence, so that the radially lower side of the end of the sub-working belt layer (B) is engaged with the inflection point of the upper isolation adhesive. S9, Tread laying and forming: Tread rubber (4) is laid on the radial outer side of the hydrophobic belt layer (A) and the isolation rubber (3) to form a green tire blank; S10. Vulcanization and shaping treatment: The green tire blank obtained in step S9 is placed in a vulcanization mold for vulcanization treatment to obtain the finished tire for heavy-duty engineering.

6. The method for preparing a stress dispersion structure for the belt layer of a heavy-duty engineering tire according to claim 5, characterized in that: In step S1, the preparation of the isolation adhesive (3) component specifically includes: S1.1, Extrusion shaping: The rubber compound of the isolation type rubber (3) is extruded through the shaped die plate to obtain a continuous rubber strip with a preliminary inflection point tooth profile; S1.2, Shaping and Cooling: The continuous adhesive strip obtained in step S1.1 is passed through a shaping channel under wind conditions. The inner wall of the shaping channel has a convex support structure corresponding to the inflection point teeth of the isolation adhesive (3). The cooling air temperature is controlled at 15℃ to 25℃ and the wind speed is controlled at 3m / s to 8m / s. S1.3, Slitting and collecting: Cut the continuous rubber strip after shaping and cooling into preset lengths to obtain the isolation type rubber (3) finished parts.

7. The method for preparing a stress dispersion structure for the belt layer of a heavy-duty engineering tire according to claim 6, characterized in that: The convex support structure is used to apply continuous shape constraint to the inflection point of the isolation adhesive (3) to ensure that the inflection point angle tolerance is ±1.0° to ±1.5° after cooling and shrinkage.

8. The method for preparing a stress dispersion structure for the belt layer of a heavy-duty engineering tire according to claim 5, characterized in that: In step S1, the thickness of the low hardness transition portion of the shoulder pad adhesive component (2) is 0.8 mm to 2.5 mm, and a Shore A hardness gradient transition region is formed between the low hardness transition portion and the main body portion, and the width of the hardness gradient transition region is 3 mm to 8 mm.

9. The method for preparing a stress dispersion structure for the belt layer of a heavy-duty engineering tire according to claim 5, characterized in that: In steps S5 and S7, the inflection point area of ​​the isolation adhesive (3) is preheated before bonding; after bonding, the bonding area is rolled.

10. The method for preparing a stress dispersion structure for the belt layer of a heavy-duty engineering tire according to claim 5, characterized in that: In step S10, the vulcanization treatment is carried out at a temperature of 140°C to 160°C, a pressure of 1.8 MPa to 2.5 MPa, and a time of 90 minutes to 130 minutes.

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