Extrusion and injection composite molding of a non-pneumatic tire and method of processing

Abstract

This invention discloses an extrusion and injection molding composite airless tire and its processing method, belonging to the field of airless tire molding technology. The extrusion and injection molding composite molded airless tire and its processing method include an inner tire layer with a cavity circumferentially formed in the center. A composite tire layer is coaxially fitted onto the outer layer of the inner tire layer. An elastic skeleton material is wound within the threaded grooves of the partially cross-linked vulcanized tire body. The skeleton material undergoes pre-processing such as impregnation before winding, ensuring a tighter fit between the inner and outer tire layers at the junction through the threaded grooves. This allows for a clear division of functions such as load-bearing and comfort, and to some extent solves the problem of unevenness at the tire joint in traditional tire manufacturing processes.

Description

Technical Field

[0001] This invention relates to the field of pneumatic tire molding technology, and more specifically to a pneumatic tire manufactured by extrusion and injection molding and its processing method. Background Technology

[0002] Tires are divided into pneumatic tires and tubeless tires. Traditional pneumatic tires are widely used due to their mature manufacturing process, good shock absorption, comfortable riding experience, and good load-bearing capacity. However, with the increasing number of vehicle accidents caused by tire blowouts, wear, and unstable operation, tubeless tires, which are tubeless, are gaining attention due to their high safety, energy efficiency, and environmental friendliness. Tubeless tires are further divided into solid tires and hollow tires. Hollow tires largely solve the problem of insufficient resilience and bumpy rides caused by insufficient rebound in tubeless tires.

[0003] A search revealed a Chinese patent, CN109109352A, published on January 1, 2019, which discloses a method for one-time injection molding, hollow molding, and vulcanization of rubber products. This method can complete the injection, hollow molding, and vulcanization processes within the same mold cavity. The mold cavity includes an upper mold, a lower mold, and a mold core. The mold core lays the foundation for the hollowing of the mold cavity, providing the conditions for filling with the high-temperature and high-pressure gas required for vulcanization. This integrates the injection molding, hollow molding, and vulcanization devices, avoiding the need for separate devices in existing technologies. While the heat loss and process flow costs caused by the process flow have greatly improved the shortcomings of the traditional complex process and simplified the manufacturing process, it has been found through the use of this process that although it can theoretically achieve fully automated production, in actual production, the hollow tire vulcanization process requires the introduction of high-temperature gas or compressed air to heat the inner cavity, resulting in a low yield of hollow tires. At the same time, the need for high-temperature gas or compressed air during equipment operation poses safety hazards and increases the responsibility coefficient of the product realization process, making it difficult to achieve large-scale industrial production.

[0004] For example, a representative of traditional airless tires is the airless hollow tire produced by Jiangxin Tire. The airless hollow tire launched by the company is based on the traditional solid tire with a hollow, porous structure to improve the comfort of the solid tire. It uses a screw extruder and a multi-hole die to extrude a tubular tire blank, supplemented by butt molding process and traditional compression vulcanization molding to obtain the airless hollow tire. Its advantages are that it does not require inflation and is easy to maintain, has a long service life, is puncture-resistant, and wear-resistant. Its disadvantages are that the problem of riding comfort has not been fundamentally solved, the tire body can only be designed to be small, and the production process is relatively complex. Summary of the Invention

[0005] 1. The technical problem that the invention aims to solve

[0006] To address the issues of poor sealing at the joint of pneumatic tires manufactured in existing technologies, this invention proposes an extrusion and injection molding pneumatic tire and its processing method. A composite tire layer is fitted onto the outer layer of the inner tire layer. The junction of the inner and outer tire layers is interlocked by threaded grooves and fused together by vulcanization cross-linking. This solves the safety problems such as vibration, bumps, and even breakage during riding caused by unevenness at the tire joint.

[0007] 2. Technical Solution

[0008] To achieve the above objectives, the technical solution provided by the present invention is as follows:

[0009] An extrusion-injection composite molded pneumatic tire includes a tire carcass, which includes an inner tube layer. A cavity is formed circumferentially in the center of the inner tube layer, which can largely solve the problem of insufficient resilience causing bumps during riding in pneumatic tires. The outer circumferential surface of the inner tube layer is provided with threaded grooves, and a composite tire layer is coaxially fitted onto its outer layer. The threaded grooves formed between the outer circumferential surface of the inner tube layer and the composite tire layer are arc-shaped connected threaded grooves I. The junction of the inner and outer tire layers is interlocked by the threaded grooves I and fused together by vulcanization cross-linking, thus solving the safety problems of vibration, bumps, and even breakage during riding caused by unevenness at the tire joint.

[0010] A further technical solution is that the threaded groove formed between the outer circumferential surface of the inner tire layer and the composite tire layer is a V-shaped threaded groove II, which increases the contact area at the junction of the inner and outer tire layers, making the joint tighter and ensuring effective adhesion between the inner tire layer and the composite tire layer, thereby effectively solving the problem of uniformity at the tire joint.

[0011] A further technical solution involves using extruded rubber compound A as the inner layer material. Extruded rubber compound A focuses on load-bearing capacity and possesses the properties of a skeleton material, enabling precise and better optimization of the formed tire, thereby improving the tire's structural strength. The composite tire layer material is injection-molded rubber compound B, which focuses on comfort, resulting in good wear resistance, flexural strength, wet skid resistance, and cushioning performance. After the extruded rubber compound A is compounded with injection-molded rubber compound B, under the premise of greater safety, the functions of load-bearing capacity and comfort are clearly divided, and the problem of unevenness at the tire joint in traditional tire manufacturing processes can be solved to a certain extent.

[0012] A method for processing an extrusion and injection molded pneumatic tire includes the following steps:

[0013] Step 1: Extruding the tubular inner tube layer: Add rubber compound A into the screw extruder and then extrude the tubular inner tube layer;

[0014] Step 2, Mold A opening: Cut the extruded tubular inner tube layer according to the tire size, and join the ends together to form a shape. Then place it in mold A on the flat vulcanizing machine for mold closing.

[0015] Step 3, Partial Cross-linking Vulcanization: Insert the inflation tube along the direction perpendicular to the inner circumference of the tire body, and introduce compressed air into the inner tube cavity. The input compressed air is about 1.0 MPa, so that the compressed air fills the entire cavity. Then, mold the upper and lower molds of mold A to complete the partial cross-linking vulcanization, thereby weakening the joint stress and strengthening the overall performance.

[0016] Step 4, Mold B opening: Take the partially cross-linked and vulcanized tire carcass out of mold A, then place it into mold B on the injection molding machine, place it against the inner cavity of the mold, and close the mold.

[0017] Step 5: Injecting B compound: Inject the B compound into the B mold using an injection molding machine until the B compound fills the mold and forms a composite tire layer around the inner tire layer, making the tire carcass wear-resistant and slip-resistant.

[0018] Step Six: Vulcanization Molding: Compressed air is introduced into the bladder cavity of the composite tire body at a pressure of approximately 1.0 MPa, filling the entire cavity and initiating vulcanization molding. This process promotes the cross-linking and bonding of the injected rubber compound with the inner tube layer, forming a unified whole. This addresses potential joint problems: if the joint is too tight, a bulge will appear at the joint, causing abrupt changes in the internal structure and leading to bumps and poor riding comfort; if the joint is too loose, a depression will appear at the joint, also causing bumps and even breakage, resulting in poor riding comfort and significant safety hazards.

[0019] In a further technical solution, in step two, a vent hole is opened on the inner circumferential surface of mold A, and an inflation tube is inserted along the direction perpendicular to the inner circumferential surface of the tire body to introduce compressed air into the bladder cavity of the inner tire layer. This ensures that the bladder cavity is filled with compressed air during the subsequent cross-linking and vulcanization process, preventing deformation of the bladder cavity channel due to the pressure generated by molding, and promoting better vulcanization of the rubber material in the bladder cavity channel. The inner wall of the molding cavity of mold A is provided with a threaded concave-convex structure, so that the outer circumferential surface of the inner tire layer molded inside it forms a corresponding threaded concave-convex groove. The inner circumferential surface of the composite tire layer formed after the injection of rubber B matches the threaded concave-convex groove on the outer circumferential surface of the inner tire layer, so that the inner tire layer acts as a support frame structural component, bearing the tire load and providing cushioning. The composite tire layer formed by the injected rubber B acts as the tire tread, providing tire wear resistance and anti-skid properties, thus combining the advantages of extrusion and injection processes.

[0020] In a further technical solution, in step four, the thickness of the tire carcass placed in mold B is greater than the height of the mold cavity after mold B is closed. By completely separating the inner and outer peripheral surfaces of the tire carcass, compressed air is injected after mold closure, which expands the outer diameter of the tire carcass to a certain extent. This provides a reinforced track to eliminate the risk of bumps or breakage in the joint process, ensuring that mold B on the injection molding machine can press the tire carcass tightly after mold closure. This prevents the B rubber material from entering the inner peripheral surface of the inner tire layer when the B rubber material is injected under high pressure, thereby affecting the overall structure of the finished tire.

[0021] A further technical solution involves opening an injection port on the outer peripheral surface of mold B, thereby forming a composite tire layer in the reinforced track area reserved on the outer peripheral surface of the inner tire layer; and opening a vent hole on the inner peripheral surface of mold B, thereby ensuring that the cavity is filled with compressed air during the cross-linking vulcanization process, preventing deformation of the cavity channel caused by the pressure generated by molding, and promoting better vulcanization of the rubber material in the cavity channel.

[0022] In a further technical solution, step three involves winding an elastic skeleton material within the threaded grooves of the partially cross-linked vulcanized tire carcass. This enhances the bonding force between the inner and composite tire layers, facilitating their integration into a single unit by using the skeleton material as a bridge. It also offers advantages such as increased tire support and comfort, reduced overall tire weight, and lower raw material costs. Before winding, the skeleton material undergoes pre-processing such as impregnation, but is not limited to impregnation, to prevent the skeleton material from forming a puncture-like structure between the inner and composite tire layers, which could generate stress and affect the internal stability of the tire carcass.

[0023] 3. Beneficial effects

[0024] Compared with the prior art, the technical solution provided by this invention has the following advantages:

[0025] (1) The present invention provides an extrusion and injection composite molding pneumatic tire and its processing method, wherein a composite tire layer is fitted onto the outer layer of the inner tire layer, and the threaded groove formed between the outer circumferential surface of the inner tire layer and the composite tire layer is a threaded groove I connected in an arc shape. The two tire layers intersect each other by means of the threaded groove I and are fused together by vulcanization crosslinking, so as to solve the safety problems such as shaking, bumping and even breakage caused by unevenness at the tire joint during riding.

[0026] (2) The extrusion and injection composite molding non-pneumatic tire and its processing method of the present invention, wherein the threaded groove formed between the outer peripheral surface of the inner tire layer and the composite tire layer is a V-shaped threaded groove II, thereby increasing the contact area at the junction of the inner and outer tire layers and making the junction tighter, so as to ensure effective adhesion between the inner tire layer and the composite tire layer, thereby effectively solving the problem of uniformity at the tire joint.

[0027] (3) The present invention provides an extrusion and injection composite molded pneumatic tire and its processing method, wherein the inner tire layer material is extruded rubber compound A, which focuses on load, and has the properties of skeleton material, thereby improving the structural strength of the tire; the composite tire layer material is injection rubber compound B, which focuses on comfort, making the tire wear-resistant, flexural-resistant, wet-slip-resistant and cushioning-good. After the extruded rubber compound A is composited with the injection rubber compound B, under the premise of greater safety, the tire riding comfort and tire load capacity are taken into account, and the problem of unevenness at the tire joint in the traditional tire production process can be solved to a certain extent.

[0028] (4) The present invention provides an extrusion and injection composite molding pneumatic tire and its processing method. The inner wall of the molding cavity of the A mold is provided with a threaded concave-convex structure, so that the outer peripheral surface of the inner tire layer molded inside it forms a corresponding threaded concave-convex groove. The inner peripheral surface of the composite tire layer formed after the B rubber is injected matches the threaded concave-convex groove on the outer peripheral surface of the inner tire layer, so that the inner tire layer acts as a support frame structure component, bearing the tire load and buffering function, etc.; the composite tire layer formed by the injected B rubber acts as the tire tread, playing the role of tire wear resistance and anti-skid, thus combining the advantages of extrusion process and injection process into one.

[0029] (5) The present invention provides an extrusion and injection composite molding pneumatic tire and its processing method. The thickness of the tire body placed in the B mold is greater than the height of the mold cavity after the B mold is closed. By completely separating the inner and outer peripheral surfaces of the tire body, compressed air is filled after the mold is closed, so that the outer diameter of the tire body is expanded to a certain extent. This provides a reinforced track to eliminate the bumps or breakage hazards of the joint process, so as to ensure that the B mold on the injection machine can press the tire body tightly after the mold is closed, so as to prevent the B rubber material from entering the inner peripheral surface of the inner tire layer when the B rubber material is injected under high pressure, thereby affecting the overall structure of the finished tire.

[0030] (6) The present invention provides an extrusion and injection composite molded pneumatic tire and its processing method, wherein an elastic skeleton material is wound in the threaded groove of the partially cross-linked vulcanized tire body to enhance the bonding force between the inner tire layer and the composite tire layer, and further integrates them into a whole by relying on the skeleton material as a bridge; it also has the advantages of enhancing the tire's support and comfort, reducing the overall weight of the tire, and reducing the cost of raw materials; the skeleton material needs to be pre-processed (not limited to impregnation) before winding to avoid the skeleton material forming a puncture-like structure between the inner tire layer and the composite tire layer, generating stress and affecting the internal stability of the tire body;

[0031] (7) The present invention discloses an extrusion and injection molding pneumatic tire and its processing method. The extruded compound A focuses on load-bearing capacity and includes 25-35% natural rubber, 8-10% high-styrene masterbatch, and 15-20% recycled rubber. The blending of natural rubber, high-styrene masterbatch, and recycled rubber provides good stiffness, which helps improve the support performance of the tire skeleton, highlighting the tire's support and load-bearing functions. The injection compound B focuses on comfort and includes 45-65% rubber (natural rubber, styrene-butadiene rubber, butadiene rubber, etc.). Natural rubber has good elasticity, styrene-butadiene rubber has good wet skid resistance, and butadiene rubber has good wear resistance. Blending with other compounding agents enhances the tire's elasticity, wet skid resistance, and wear resistance. Compared to traditional tires, since the tire of the present invention has two layers, inner and outer, only the proportion of high-performance rubber added to the injection compound B used in the outer layer needs to be increased, thereby saving costs. Attached Figure Description

[0032] Figure 1 A schematic diagram of the three-dimensional structure of an existing pneumatic tire;

[0033] Figure 2 This is a schematic diagram of the longitudinal section structure of the pneumatic tire of the present invention;

[0034] Figure 3 for Figure 2 Enlarged structural diagram of section A;

[0035] Figure 4 This is a schematic diagram of the three-dimensional structure of mold A in this invention;

[0036] Figure 5 This is a schematic diagram of the three-dimensional structure of mold B in this invention;

[0037] Figure 6 This is a schematic diagram of the longitudinal section structure of the pneumatic tire of the present invention;

[0038] Figure 7 for Figure 6 Enlarged structural diagram of section B.

[0039] In the diagram: 1-Carcass; 2-Cavity; 3-Mold A; 4-Mold B; 11-Inner tire layer; 12-Composite tire layer; 13-Inner circumferential surface of the tire body; 31-Threaded concave-convex structure; 32-Ventilation hole I; 41-Injection port; 42-Ventilation hole II; 111-Threaded concave-convex groove I; 112-Threaded concave-convex groove II. Detailed Implementation

[0040] To further understand the content of this invention, a detailed description of the invention is provided in conjunction with the accompanying drawings.

[0041] Example 1

[0042] This embodiment describes an extrusion and injection molding composite molded pneumatic tire, such as... Figure 2 As shown, the tire includes a carcass 1, which includes an inner tube 11. A cavity 2 is formed circumferentially in the center of the inner tube 11. The outer circumferential surface of the inner tube 11 has threaded grooves. A composite tire layer 12 is coaxially fitted onto the outer layer and fused together using vulcanization cross-linking. This design aims to address safety issues such as vibration, bumps, and even breakage during riding caused by unevenness at the tire joint. Figure 1 As shown, compared with existing airless tires, the airless tire of the present invention can largely solve the problem of bumpy ride caused by insufficient resilience during the riding process of airless tires.

[0043] In this embodiment, as Figures 2-3 As shown, the threaded groove formed between the outer circumferential surface of the inner tire layer 11 and the composite tire layer 12 is a circular arc-shaped threaded groove I111. The inner and outer tire layers interlock with each other through the threaded groove I111 to solve the safety problems such as vibration, bumps, and even breakage caused by unevenness at the tire joint. The inner tire layer 11 is made of extruded rubber compound A, which focuses on load-bearing capacity. Extruded rubber compound A includes 25-35% natural rubber, 8-10% high-styrene masterbatch, and 15-20% recycled rubber. The tire is made from a blend of raw rubber, including natural rubber, high-styrene masterbatch, and recycled rubber. This blend exhibits good stiffness, which helps improve the support performance of the tire skeleton, emphasizing the tire's support and load-bearing functions. The composite tire layer 12 is made of injection molding compound B, which focuses on comfort. Injection molding compound B includes 45-65% rubber (natural rubber, styrene-butadiene rubber, butadiene rubber, etc.), among which natural rubber has good elasticity, styrene-butadiene rubber has good wet skid resistance, and butadiene rubber has good wear resistance. By blending with other compounding agents, the tire exhibits better elasticity, wet skid resistance, and wear resistance. Compared to traditional tires, since the tire of this invention has two layers, inner and outer, only the proportion of high-performance rubber added to the injection molding compound B used in the outer layer needs to be increased, thereby saving costs. After the outer layer of extruded rubber compound A is composited with injection-molded rubber compound B, under the premise of greater safety, the functions of load-bearing and comfort are clearly divided, and the problem of unevenness at the tire joint in traditional tire production processes can be solved to a certain extent. The two types of rubber compounds are interlocked (fitted and welded) by means of threaded grooves I111 (single or multiple strands, parallel or alternating), and then fused together by chemical vulcanization cross-linking of polymer materials.

[0044] Example 2

[0045] This embodiment of an extrusion and injection molded pneumatic tire has the same basic structure as Embodiment 1, but the differences and improvements are as follows: Figures 6-7As shown, the threaded groove formed between the outer circumferential surface of the inner tire layer 11 and the composite tire layer 12 is a V-shaped threaded groove II112, which increases the contact area at the junction of the inner and outer tire layers, making the joint tighter and ensuring effective adhesion between the inner tire layer 11 and the composite tire layer 12, thereby effectively solving the problem of uniformity at the tire joint.

[0046] Example 3

[0047] This embodiment of the method for processing an extrusion and injection composite molded pneumatic tire has the same basic structure as Embodiment 2, but the differences and improvements are as follows: It includes the following steps:

[0048] Step 1: Extruding the tubular inner tube layer 11: Add rubber compound A into the screw extruder and then extrude the tubular inner tube layer 11;

[0049] Step 2, Mold A 3 opening: Cut the extruded tubular inner tube layer 11 according to the tire size, and join the ends together to form a shape. Then place it on mold A 3 on the flat vulcanizing machine for mold closing.

[0050] Step 3, partial cross-linking vulcanization: Insert the inflation tube inward along the direction perpendicular to the inner circumferential surface 13 of the tire body, and introduce compressed air into the bladder 2 of the inner tire layer 11. The input compressed air is about 1.0 MPa, so that the compressed air fills the entire bladder 2. Then, mold the upper and lower molds of mold A to complete the partial cross-linking vulcanization, thereby weakening the joint stress and strengthening the overall performance.

[0051] Step 4, Mold B opening: Take the partially cross-linked and vulcanized tire body 1 out of mold A 3, then place it into mold B 4 on the injection molding machine, place it against the inner cavity of the mold, and close the mold.

[0052] Step 5: Injecting B rubber compound: Inject B rubber compound into B mold 4 using an injection molding machine until the mold is full and a composite tire layer 12 is formed around the inner tire layer 11, making the tire carcass 1 wear-resistant and slip-resistant on the outside.

[0053] Step Six: Vulcanization Molding: Insert the inflation tube inward along the direction perpendicular to the inner circumferential surface 13 of the tire body, and introduce compressed air into the bladder cavity 2 of the composite tire body 1. The input compressed air pressure is approximately 1.0 MPa, so that the compressed air fills the entire bladder cavity 2, and vulcanization molding is carried out. This promotes the vulcanization and cross-linking of the injected rubber material with the inner tire layer 11 to form a unified whole, thereby solving the joint problems. If the joint is too tight, a bulge will appear at the joint, the internal structure shape will change abruptly, and it will be prone to bumps, resulting in poor riding comfort. If the joint is too loose, a depression will appear at the joint, which will be prone to bumps and may even break, resulting in poor riding comfort and significant safety hazards.

[0054] In this embodiment, in step two, as follows: Figure 4As shown, the inner circumferential surface of mold A 3 is provided with a vent hole I32. An inflation tube is inserted along the direction perpendicular to the inner circumferential surface of the tire body, and compressed air is introduced into the bladder 2 of the inner tire layer 11. This ensures that the bladder 2 is filled with compressed air during the subsequent cross-linking and vulcanization process, preventing deformation of the bladder 2 channel due to the pressure generated by molding, and promoting better vulcanization of the rubber material in the bladder 2 channel. The inner wall of the molding cavity of mold A 3 is provided with a threaded concave-convex structure 31, so that the outer circumferential surface of the inner tire layer 11 molded inside it forms a corresponding threaded concave-convex groove I111. The inner circumferential surface of the composite tire layer 12 formed after the injection of the B rubber material matches the threaded concave-convex groove I111 on the outer circumferential surface of the inner tire layer 11, so that the inner tire layer 11 acts as a support frame structural component, bearing the tire load and providing cushioning. The composite tire layer 12 formed by the injected B rubber material acts as the tire tread, providing tire wear resistance and anti-skid properties, thus combining the advantages of extrusion and injection processes.

[0055] In step four, such as Figure 5 As shown, the outer circumferential surface of the B mold 4 has an injection port 41, thereby forming a composite tire layer 12 in the reinforced track area reserved on the outer circumferential surface of the inner tire layer 11; the inner circumferential surface of the B mold 4 has a vent hole II 42, thereby ensuring that the cavity 2 is filled with compressed air during the cross-linking vulcanization process, preventing the pressure generated by molding from causing deformation in the cavity 2 channel, and promoting better vulcanization of the rubber material in the cavity 2 channel; the thickness of the tire body 1 placed in the B mold 4 is greater than the height of the mold cavity after the B mold 4 is closed. By completely separating the inner and outer circumferential surfaces of the tire body 1, and filling it with compressed air after mold closing, the outer diameter of the tire body 1 is expanded to a certain extent, thereby reserving a reinforced track to eliminate the risk of bumps or breakage in the joint process, so as to ensure that the B mold 4 on the injection molding machine can press the tire body 1 tightly after mold closing, so as to prevent the B rubber material from entering the inner circumferential surface 13 of the inner tire layer 11 when the B rubber material is injected under high pressure, thereby affecting the overall structure of the finished tire.

[0056] Airless hollow tires produced by simple extrusion + molding (flat vulcanization) processes and used in electric vehicles and bicycles suffer from significantly lower riding comfort compared to traditional pneumatic tires due to their lower rebound and cushioning performance, and relatively heavier weight. They also experience higher energy consumption, require more effort, and are prone to severe bumps during riding. Furthermore, they fail to balance riding comfort with load-bearing capacity. This invention combines the traditional airless tire (extrusion + flat vulcanization) production process with injection molding, integrating the advantages of both technologies to create a composite technology that results in a safer and more comfortable tire. The traditional tire production process (extrusion + flat vulcanization molding) has advantages such as simple process, low equipment cost, and ease of mass production. However, it has disadvantages: because the extruded tubular tire blank needs to be cut and joined according to tire size before vulcanization, unevenness can easily occur at the tire joint, leading to vibration, bumps, and even breakage during riding, severely affecting riding comfort and potentially causing traffic accidents. Modern tire manufacturing processes (injection molding) offer advantages such as high automation, low labor intensity, simplified operation, and better overall tire uniformity. This, to some extent, addresses the unevenness at the tire joint that exists in traditional tire manufacturing processes. The injection molding process, through its composite technology, minimizes and optimizes potential joint defects (overly tight joints result in bulges, abrupt changes in internal structure, and poor riding comfort; loose joints result in depressions, leading to bumps, even breakage, poor riding comfort, and significant safety hazards). These defects are eliminated or optimized as much as possible (the injection molding process uses pre-reserved spiral injection tracks, welded reinforcement, and utilizes high-molecular chemical bonds for vulcanization and cross-linking to fuse the tire together).

[0057] Example 4

[0058] This embodiment of the method for processing an extrusion and injection composite molded pneumatic tire has the same basic structure as Embodiment 3, but the difference and improvement are as follows: it includes the following steps:

[0059] Step 1: Extruding the tubular inner tube layer 11: Add rubber compound A into the screw extruder and then extrude the tubular inner tube layer 11;

[0060] Step 2, Mold A 3 opening: Cut the extruded tubular inner tube layer 11 according to the tire size, and join the ends together to form a shape. Then place it on mold A 3 on the flat vulcanizing machine for mold closing.

[0061] Step 3, partial cross-linking vulcanization: Compressed air is introduced into the bladder cavity 14 of the inner tube 11. The input compressed air is about 1.0 MPa, so that the compressed air fills the entire bladder cavity 2. Then, the upper and lower molds of mold A are pressed to complete the partial cross-linking vulcanization, thereby weakening the joint stress and strengthening the overall performance.

[0062] Step 4, Mold B opening: Take the partially cross-linked and vulcanized tire body 1 out of mold A 3, then place it into mold B 4 on the injection molding machine, place it against the inner cavity of the mold, and close the mold.

[0063] Step 5: Injecting B rubber compound: Inject B rubber compound into B mold 4 using an injection molding machine until the mold is full and a composite tire layer 12 is formed around the inner tire layer 11, making the tire carcass 1 wear-resistant and slip-resistant on the outside.

[0064] Step 6, vulcanization molding: Compressed air is introduced into the cavity through hole 14 of the composite carcass 1, and the input compressed air pressure is about 1.0 MPa.

[0065] In this embodiment, in step one, the outer diameter of the tube of the extruded inner tire layer 11 is smaller than the outer diameter of the finished tire (approximately 70%), thus reserving a covering space to eliminate the risk of bumps or breakage in the joint process in subsequent processes; in step five, the outer diameter of the tube of the carcass 1 formed by injection before molding and vulcanization of the composite tire layer 12 is smaller than the outer diameter of the finished tire (approximately 80%). Since the filling of compressed air in step six will cause its outer diameter to expand to a certain extent, in order to eliminate the risk of bumps or breakage in the joint process, a reinforced track is reserved to ensure that subsequent processes can proceed smoothly.

[0066] like Figure 4 As shown, the inner circumference of mold A 3 has a vent I32 corresponding to the bladder cavity through hole 14. By introducing compressed air into the bladder cavity through hole 14 of the inner tire layer 11, it is ensured that the bladder cavity 2 is filled with compressed air during the subsequent cross-linking vulcanization process. This prevents the pressure generated by molding from causing deformation in the bladder cavity 2 channel and promotes better vulcanization of the rubber material in the bladder cavity 2 channel. The inner wall of the molding cavity of mold A 3 has a threaded concave-convex structure 31, so that the outer circumference of the inner tire layer 11 molded inside it forms a corresponding threaded concave-convex groove II112. The inner circumference of the composite tire layer 12 formed after the injection of the B rubber material matches the threaded concave-convex groove II112 on the outer circumference of the inner tire layer 11, so that the inner tire layer 11 acts as a support frame structural component, bearing the tire load and providing cushioning. The composite tire layer 12 formed by the injected B rubber material acts as the tire tread, providing tire wear resistance and anti-skid properties, thus combining the advantages of extrusion and injection processes.

[0067] like Figures 6-7 As shown, the threaded groove II112 has a V-shaped interconnected structure to increase the contact area at the junction of the inner tire layer 11 and the composite tire layer 12, thereby making the bonding between the inner and outer tire layers tighter, ensuring effective adhesion between the inner tire layer and the composite tire layer, and ultimately effectively solving the problem of uniformity at the tire joint.

[0068] Example 5

[0069] This embodiment of the method for processing an extrusion and injection composite molded pneumatic tire has the same basic structure as Embodiment 4, but the difference and improvement are as follows: it includes the following steps:

[0070] Step 1: Extruding the tubular inner tube layer 11: Add rubber compound A into the screw extruder and then extrude the tubular inner tube layer 11;

[0071] Step 2, Mold A 3 opening: Cut the extruded tubular inner tube layer 11 according to the tire size, and join the ends together to form a shape. Then place it on mold A 3 on the flat vulcanizing machine for mold closing.

[0072] Step 3, partial cross-linking vulcanization: Compressed air is introduced into the bladder cavity 14 of the inner tube 11. The input compressed air is about 1.0 MPa, so that the compressed air fills the entire bladder cavity 2. Then, the upper and lower molds of mold A are pressed to complete the partial cross-linking vulcanization, thereby weakening the joint stress and strengthening the overall performance.

[0073] Step 4: Winding the elastic skeleton material: Wind the elastic skeleton material into the threaded groove of the tire body 1. The elastic skeleton material has been pre-processed by impregnation with resin.

[0074] Step 5, Mold B Opening 4: Place the partially cross-linked and vulcanized tire carcass 1 into the mold B 4 on the injection molding machine, place it against the inner cavity of the mold, and close the mold;

[0075] Step 6: Injecting B rubber compound: Inject B rubber compound into B mold 4 using an injection molding machine until the mold is full and a composite tire layer 12 is formed around the inner tire layer 11, making the tire carcass 1 wear-resistant and slip-resistant on the outside.

[0076] Step 7, vulcanization molding: Compressed air is introduced into the cavity through hole 14 of the composite carcass 1, and the input compressed air pressure is about 1.0 MPa.

[0077] In this embodiment, an elastic skeleton material is wound within the threaded groove to enhance the bonding force between the inner tube layer 11 and the composite tire layer 12. This helps to bridge the two systems using the skeleton material and further integrate them into a whole, effectively preventing the composite tire layer 12 from detaching from the inner tube layer 11. This addresses safety issues such as vibration, bumps, and even breakage caused by unevenness at the tire joint. It also enhances tire support and comfort, reduces overall tire weight, and lowers raw material costs. Before winding, the skeleton material needs to undergo pre-processing treatments such as impregnation (not limited to impregnation) to prevent the skeleton material from forming a puncture-like structure between the inner tube layer 11 and the composite tire layer 12, which could generate stress and affect the internal stability of the tire.

[0078] The present invention and its embodiments have been described above illustratively. This description is not restrictive, and the figures shown are only one embodiment of the present invention; the actual structure is not limited thereto. Therefore, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the present invention, such designs should fall within the protection scope of the present invention.

Claims

1. A process for the extrusion and injection-composite moulding of a run-flat tyre comprising a carcass (1), characterised in that: The tire body (1) includes an inner tube layer (11), and a cavity (2) is provided in the middle of the inner tube layer (11) along its circumference; the outer circumferential surface of the inner tube layer (11) is provided with a threaded groove, and a composite tire layer (12) is coaxially fitted to its outer layer. The threaded groove formed between the outer peripheral surface of the inner tire layer (11) and the composite tire layer (12) is either a threaded groove I (111) connected in an arc shape or a threaded groove II (112) connected in a V shape; the material of the inner tire layer (11) is extruded rubber A, and the material of the composite tire layer (12) is injection rubber B: the inner peripheral surface of the composite tire layer (12) formed after the B rubber is injected fits the threaded groove on the outer peripheral surface of the inner tire layer (11), and the threaded groove is wrapped with an elastic skeleton material that has been pretreated by impregnation. The inner tire layer (11) is made of extruded rubber compound A, which includes 25-35% natural rubber, 8-10% high styrene masterbatch, and 15-20% recycled rubber, and has the skeletal properties to support the load; the composite tire layer (12) is made of injection molding compound B, which includes 45-65% natural rubber, styrene-butadiene rubber or cis-butadiene rubber, and has wear resistance, flexural resistance and cushioning properties; The inner circumferential surface of the composite tire layer (12) formed after the injection of the B rubber compound matches the threaded groove on the outer circumferential surface of the inner tire layer (11), and the threaded groove is wrapped with an elastic skeleton material that has been pretreated by impregnation. The inner tire layer (11) is formed by extrusion through an extruder, and the composite tire layer (12) is formed by injection molding through an injection molding machine. The two are fused together by vulcanization crosslinking. The processing method includes the following steps: Step 1: Extruding the tubular inner tube layer (11): Add rubber compound A into the screw extruder and then extrude the tubular inner tube layer (11). Step 2, Mold A (3) opening: Cut the extruded tubular inner tube layer (11) according to the tire size, and then connect the ends to form a mold. Then place it in mold A (3) on the flat vulcanizing machine for mold closing. Step 3, partial cross-linking vulcanization: Insert the inflation tube along the direction perpendicular to the inner circumferential surface (13) of the tire, and introduce compressed air into the bladder (2) of the inner tire layer (11) so that the compressed air fills the entire bladder (2). Then, mold the upper and lower molds of mold A (3) to complete the partial cross-linking vulcanization. Step 4, Mold B (4) opening: Take the partially cross-linked vulcanized carcass (1) out of mold A (3), and then put it into mold B (4) on the injection molding machine, place it against the inner cavity of the mold, and close the mold; Step 5: Inject B rubber: Inject B rubber into B mold (4) using an injection molding machine until B rubber fills the mold and forms a composite tire layer (12) around the inner tire layer (11). Step 6, vulcanization molding: Compressed air is introduced into the cavity (2) of the composite carcass (1) so that the compressed air fills the entire cavity (2) and vulcanization molding is performed.

2. The method of claim 1, wherein: In step two, the inner circumferential surface of mold A (3) is provided with a ventilation hole I (32); the inner wall of the molding cavity of mold A (3) is provided with a threaded concave-convex structure (31), so that the outer circumferential surface of the inner tube layer (11) molded inside it forms a corresponding threaded concave-convex groove.

3. The method of claim 1, wherein: the tire is an airless tire. In step four, the thickness of the tire body (1) placed in mold B (4) is greater than the height of the mold cavity after mold B (4) is closed, thus completely separating the inner and outer circumferences of the tire body (1).

4. The method of claim 3, wherein the tire is an airless tire. The B mold (4) has an injection port (41) on its outer circumferential surface and a vent hole II (42) on its inner circumferential surface.

5. The method of claim 3, wherein: the extrusion and injection molding of the tire is performed in a single step. In step three, an elastic skeleton material is wound into the threaded groove of the partially cross-linked vulcanized carcass (1). The skeleton material needs to be pre-processed before winding, and the pre-processing includes, but is not limited to, impregnation.

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