High-temperature-resistant annular rubber conveying belt preparation system and method

Abstract

The invention discloses a high-temperature-resistant annular rubber conveying belt preparation system and method, and relates to the technical field of rubber conveying belt preparation, the high-temperature-resistant annular rubber conveying belt preparation system comprises a raw material treatment module, a composite forming module, a gradient vulcanization module and an intelligent quality inspection module, semi-finished products of the composite forming module are conveyed to the gradient vulcanization module, and an intelligent quality inspection module is arranged at the discharging end of the gradient vulcanization module. By designing the raw material processing module, nanoscale uniform dispersion of the ethylene propylene diene monomer, the modified nano montmorillonite and the aramid short fibers and construction of a three-dimensional network structure are realized, and the high temperature resistance of the material is synergistically improved by virtue of the barrier property of the montmorillonite and the reinforcing effect of the aramid fibers; the high-temperature-resistant stability of the rubber matrix and the synergism of the mechanical property are obviously improved.

Description

Technical Field

[0001] This invention relates to the field of rubber conveyor belt manufacturing technology, specifically to a high-temperature resistant annular rubber conveyor belt manufacturing system and method. Background Technology

[0002] In high-temperature industrial fields such as metallurgy, coking, and building materials, annular rubber conveyor belts, as core components for material transport, need to operate in extreme environments above 150°C for extended periods. Their high-temperature resistance and structural stability are directly related to the continuity and safety of production.

[0003] Currently, traditional circular rubber conveyor belts mostly use natural rubber or styrene-butadiene rubber as the matrix material. The molecular chains of these materials are easily affected by high temperature and oxidative aging, which manifests as hardening and cracking in a short time in a high-temperature environment, resulting in a sharp decline in mechanical properties and failing to meet the requirements for long-term use.

[0004] Patent CN101875731B discloses an ultra-wear-resistant rubber conveyor belt cover and its preparation method. The above patent achieves improved wear resistance and reduced abrasion performance.

[0005] The conveyor belts prepared by the aforementioned patents can improve wear resistance, reduce abrasion performance, and have good cover rubber strength and elongation at break, but there is still room for improvement in high-temperature heat resistance.

[0006] Therefore, this application proposes a system and method for preparing a high-temperature resistant annular rubber conveyor belt with a three-dimensional high-temperature resistant structure through nano-montmorillonite intercalation modification and synergistic reinforcement with aramid fibers. Summary of the Invention

[0007] The purpose of this invention is to provide a high-temperature resistant annular rubber conveyor belt preparation system and method to solve the technical problem mentioned in the background art that the molecular chains of traditional annular rubber conveyor belts are easily affected by high temperature-induced thermo-oxidative aging, resulting in a short service life.

[0008] To achieve the above objectives, the present invention provides the following technical solution: a high-temperature resistant annular rubber conveyor belt preparation system, comprising a raw material processing module, a composite molding module, a gradient vulcanization module, and an intelligent quality inspection module. The raw material processing module provides a modified rubber substrate to the composite molding module. The semi-finished product from the composite molding module is conveyed to the gradient vulcanization module. An intelligent quality inspection module is provided at the discharge end of the gradient vulcanization module.

[0009] The raw material processing module includes melt blending and intercalation reactions;

[0010] The melt blending process involves melting and mixing EPDM rubber, modified nano-montmorillonite, and aramid short fibers in a mixing kettle protected by an inert gas at 130°C and 0.7 MPa. The stirring paddle in the mixing kettle is started, the speed is set to 70 r / min, and the stirring is carried out for 35 min to fully mix the EPDM rubber, modified nano-montmorillonite, and aramid short fibers.

[0011] The intercalation reaction is that modified montmorillonite, under the action of shear force and silane coupling agent, peels off layers and inserts between rubber molecular chains to form a modified rubber matrix.

[0012] Preferably, the rubber melt in the raw material processing module enters the extruder in the composite molding module through an insulated pipe, and the rubber melt in the raw material processing module is diluted and mixed to form a rubber solution which enters the prepreg tank in the composite molding module.

[0013] The composite molding module includes prepreg treatment and extrusion molding;

[0014] Pre-impregnation involves passing aramid canvas through a pre-impregnation bath with a tension of 60N. The pre-impregnation bath contains modified rubber solution with a solid content of 25%. The canvas is impregnated at 40°C for 20 seconds, during which small molecule rubber molecules gradually penetrate into the fiber bundles. After drying at 100°C, a coating layer is formed.

[0015] Extrusion molding involves feeding pre-impregnated aramid canvas between two extruders. The two extruders then uniformly coat both sides of the canvas with 140°C modified rubber melt under a pressure of 1.5 MPa, forming a three-layer structure of rubber, canvas, and rubber.

[0016] Preferably, the rubber melt is dissolved and mixed to form a rubber solution. Toluene solution is added at a ratio of 3:1 to rubber melt, followed by the addition of a vulcanizing agent. After dissolving in a reaction tank at 45°C for 3 hours, the solution is filtered through a screen to obtain a rubber solution with a solid content of 25%. The rubber solution with a solid content of 25% enters the prepreg tank in the prepreg treatment through a transmission pipeline. Another part of the rubber melt in the raw material processing module enters the upper and lower extruders through an insulated pipeline. The extruders are started, the screw rotates at 200 r / min, and the barrel temperature is set to 150°C. The rubber melt is sheared, kneaded, and plasticized evenly, forming a melt with stable fluidity after 15 minutes.

[0017] Preferably, the semi-finished product extruded by the composite molding module is transported to the gradient vulcanization module via a conveyor belt;

[0018] The gradient vulcanization module includes preheating, vulcanization, and setting.

[0019] Preheating activates the rubber molecular chains. The semi-finished product is transported to the first microwave vulcanizing chamber, where the temperature is set at 170°C and the pressure at 1.6 MPa. The modified rubber matrix is ​​heated and pressurized, and the molecular chains change from frozen to active within 3 minutes.

[0020] Vulcanization involves conveying the material to the second stage microwave vulcanizing chamber, where the temperature is set at 180℃ and the pressure at 2.0MPa. Within 6 minutes, the rubber molecular chains and vulcanizing agent rapidly cross-link to form a stable three-dimensional network structure.

[0021] The final shaping process involves transporting the finished product to the third stage microwave vulcanizing chamber, where the temperature is set at 160℃ and the pressure at 1.5MPa. The temperature is then reduced in three stages over three minutes, with each stage decreasing by 5℃, and the pressure gradually decreasing from 1.5MPa to atmospheric pressure.

[0022] Preferably, during the preheating stage, the conveyor belt blank is driven by a servo motor to be conveyed to the first microwave vulcanizing box. The silicone pressure roller driven by the hydraulic cylinder at the top of the box adheres to the surface of the blank and preheats the rubber conveyor belt. The blank enters the second microwave vulcanizing box, and the hydraulic pressurizing devices on both sides are activated to apply pressure to the rubber conveyor belt through the honeycomb-shaped ventilated pressure plate to complete the crosslinking reaction.

[0023] Preferably, the intelligent quality inspection module is equipped with a phased array ultrasonic instrument, an electronic universal testing machine, and a thermal aging test chamber. The phased array ultrasonic instrument is installed on the conveyor path at the discharge end of the gradient vulcanization module. The electronic universal testing machine is installed downstream of the ultrasonic instrument and is equipped with a 500kN high-precision tensile sensor. Standard samples are cut from the conveyor belt using an automatic sampling device to test key mechanical properties. The thermal aging test chamber is located at the end of the conveyor belt and can simulate a high-temperature environment, performing a 1000-hour thermal aging test at 200℃.

[0024] Preferably, the raw material processing module includes a mixing kettle, a twin-screw extruder, and a nano-grinding mill. The bottom outlet of the mixing kettle is connected to the inlet of the twin-screw extruder. The outlet of the twin-screw extruder is connected to the inlet of the nano-grinding mill through a high-pressure insulated pipe. The nano-grinding mill has two outlets: one outlet is connected to the reaction tank, and the other outlet is connected to the extruder in the composite module.

[0025] Preferably, the composite molding module is provided with an unwinding device and two extruders. The unwinding device outputs aramid canvas and guides the aramid canvas into the middle of the two upper and lower extruders. One discharge pipe of the nano-grinding machine is directly connected to the hopper of the extruder, and the modified rubber melt is quantitatively delivered by a gear pump.

[0026] Preferably, the method includes the following steps:

[0027] S1. Raw material processing: First, the nano-montmorillonite is modified by adding nano-montmorillonite and silane coupling agent KH550 into a mixer at a mass ratio of 10:1 and stirring at 80℃ and 1500r / min for 2 hours to obtain modified nano-montmorillonite.

[0028] S2. Mixing and Kneading: Then, 70 parts of EPDM rubber, 30 parts of modified nano montmorillonite and 15 parts of aramid short fiber are put into an inert gas protected mixing kettle. The mixing kettle is heated to 130℃ and maintained at a pressure of 0.7MPa. The mixture is mixed for 35 minutes. After the mixing is completed, the material is discharged from the mixing kettle and enters a twin-screw extruder. The twin-screw extruder shears and extrudes the material into a nano mill for grinding. The grinding is repeated 3 times to ensure that the filler particle size is less than 5μm, and the modified rubber melt is obtained.

[0029] S3. Solution preparation: Prepare pre-impregnated rubber solution by taking the rubber melt produced by the raw material processing module, adding toluene at a mass ratio of 3:1 to toluene and adding 3% of the melt mass of vulcanizing agent, and putting it into a reaction tank at 45°C. Stir at 300 r / min for 3 hours. After filtration, a rubber solution with a solid content of 25% is obtained and transported to the pre-impregnated rubber tank.

[0030] S4. Extrusion Molding: The aramid canvas is installed on the unwinding device, and the canvas passes through the pre-impregnation tank at a speed of 1.2 m / min. The temperature of the adhesive is 40℃. After impregnation for 20 seconds, it is dried for 5 minutes to form a rubber coating layer. The pre-impregnated canvas enters between the upper and lower extruders. Modified rubber melt at 140℃ is introduced into the extruder, and the pressure is set to 1.5 MPa. The flow rate is controlled by the melt pump. The upper and lower symmetrically arranged extruders extrude the rubber melt synchronously and bond it to both sides of the canvas at a pressure of 1.5 MPa.

[0031] Preferably, the method further includes the following steps:

[0032] S5. Gradient vulcanization: The semi-finished product after composite molding is conveyed to the gradient vulcanization module via a conveyor belt. First, it enters the first microwave vulcanization chamber, with the temperature set at 170℃, the pressure at 1.6MPa, and the microwave power at 30kW, and is processed for 3 minutes. Then, it enters the second microwave vulcanization chamber, with the temperature set at 180℃, the pressure at 2.0MPa, and the microwave power increased to 45kW, and is processed for 6 minutes. Finally, it enters the third microwave vulcanization chamber, with the temperature set at 160℃ and the pressure at 1.5MPa, and the microwave power reduced to 25kW, and the processing time is 3 minutes.

[0033] S6 Intelligent Quality Inspection: After vulcanization, the conveyor belt products enter the intelligent quality inspection module. First, they are fully scanned by a phased array ultrasonic instrument to identify defects such as bubbles and delamination. When the defect size is greater than 0.5mm, it is marked as unqualified. Then, samples are taken every 10m and the tensile strength and joint peel strength are tested by an electronic universal testing machine. At the same time, 3 sets of samples are placed in a heat aging test chamber and aged at 200℃ for 1000h. The tensile strength and joint peel strength are then retested.

[0034] Compared with the prior art, the beneficial effects of the present invention are:

[0035] 1. This invention, through the design of a raw material processing module, achieves nanoscale uniform dispersion and construction of a three-dimensional network structure of EPDM rubber, modified nano-montmorillonite, and aramid short fibers. By leveraging the barrier properties of montmorillonite and the reinforcing effect of aramid fibers, the high-temperature resistance of the material is synergistically improved, significantly enhancing the high-temperature stability and mechanical properties of the rubber matrix. This solves the problem of rapid thermo-oxidative aging and significant strength decay of traditional rubber materials under high-temperature conditions due to uneven component dispersion.

[0036] 2. This invention, through the design of a composite molding module, achieves deep impregnation of aramid canvas and rubber substrate and precise composite of three-layer structure, allowing small molecule rubber to fully penetrate the fiber bundle and form a stable interface, greatly improving the interlayer bonding force and overall integrity of the composite structure, and solving the problem of loose bonding between fiber and rubber interface in traditional composite processes, which easily leads to interlayer delamination during use.

[0037] 3. This invention, through the design of a gradient vulcanization module, realizes the stepwise activation, cross-linking and gradient release of internal stress of rubber molecular chains, avoids local overheating and uneven cross-linking caused by direct high temperature, ensures the uniformity and structural stability of the vulcanization process, and makes the product less prone to cracking due to internal stress concentration during long-term use. It solves the problems of large performance fluctuations and short service life caused by improper temperature and pressure control in traditional vulcanization processes.

[0038] 4. This invention, through the design of an intelligent quality inspection module, realizes fully automated inspection from internal defect identification to high-temperature performance verification, significantly improving the stability and traceability of product quality, reducing the defect rate, and solving the problems of traditional quality inspection relying on manual labor, lagging inspection, and inability to guide process adjustments in real time. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the module flow of the present invention;

[0040] Figure 2 This is a schematic diagram of the raw material processing module of the present invention;

[0041] Figure 3This is a schematic diagram of the composite molding module of the present invention;

[0042] Figure 4 This is a schematic diagram of the gradient vulcanization module of the present invention;

[0043] Figure 5 This is a schematic diagram of the raw material processing flow of the present invention;

[0044] Figure 6 This is a schematic diagram of the composite molding process of the present invention. Detailed Implementation

[0045] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "front end," "rear end," "both ends," "one end," and "the other end," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0047] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0048] Example 1, please refer to Figure 1 , Figure 2 and Figure 5One embodiment of the present invention provides a high-temperature resistant annular rubber conveyor belt preparation system. The system modifies nano-montmorillonite by mixing nano-montmorillonite and silane coupling agent KH550 at a mass ratio of 10:1 in a mixer. The mixture is stirred for 2 hours at 80°C and 1500 r / min to obtain modified nano-montmorillonite. 70 parts of EPDM rubber, 30 parts of modified nano-montmorillonite, and 15 parts of aramid short fibers are then added to an inert gas-protected mixing reactor. The reactor is heated to 130°C and maintained at a pressure of 0.7 MPa for 35 minutes. After mixing, the material is discharged from the mixing reactor into a twin-screw extruder. The twin-screw extruder shears and extrudes the material into a nano-grinding mill for grinding. The grinding process is repeated three times to ensure the filler particle size is less than 5 μm, resulting in a modified rubber melt.

[0049] To prepare the prepreg solution, the rubber melt produced by the raw material processing module is taken, and toluene is added at a mass ratio of 3:1 to the rubber melt. Then, 3% of the melt mass of vulcanizing agent is added and put into a reaction tank at 45°C. The mixture is stirred at 300 r / min for 3 hours. After filtration, a rubber solution with a solid content of 25% is obtained and transported to the prepreg tank. Then, aramid canvas is installed on the unwinding device, and the canvas passes through the prepreg tank at a speed of 1.2 m / min. The temperature of the rubber solution is 40°C. After impregnation for 20 seconds, it is dried for 5 minutes to form a rubber coating layer. The prepreg canvas enters between the upper and lower extruders. Modified rubber melt at 140°C is introduced into the extruder, and the pressure is set to 1.5 MPa. The flow rate is controlled by the melt pump so that the melt evenly wraps both sides of the canvas, forming a three-layer structure of rubber, canvas, and rubber.

[0050] The semi-finished product after composite molding is conveyed to the gradient vulcanization module via a conveyor belt. First, it enters the first microwave vulcanization chamber, where the temperature is set at 170℃, the pressure at 1.6MPa, and the microwave power at 30kW, and it is processed for 3 minutes. Then, it enters the second microwave vulcanization chamber, where the temperature is set at 180℃, the pressure at 2.0MPa, and the microwave power is increased to 45kW, and it is processed for 6 minutes. Finally, it enters the third microwave vulcanization chamber, where the temperature is set at 160℃ and the pressure at 1.5MPa, and the microwave power is reduced to 25kW, and the processing time is 3 minutes. Finally, the modified annular rubber conveyor belt is obtained.

[0051] Furthermore, the nano-montmorillonite was first modified. Nano-montmorillonite and silane coupling agent KH550 were added to a mixer at a mass ratio of 10:1 and stirred at 80℃ and 1500r / min for 2 hours to obtain modified nano-montmorillonite. According to the formula, 70 parts of EPDM rubber, 30 parts of modified nano-montmorillonite and 15 parts of aramid short fiber were added to an inert gas-protected mixing kettle. Nitrogen gas was introduced into the mixing kettle to replace the air inside the kettle. After the feed port was closed, stirring was started, and the temperature was raised to 130℃. The pressure inside the kettle was adjusted to 0.7MPa and maintained at this state for 35 minutes. The components were initially dispersed by mechanical shear force. During this period, the mixing state of the material was observed through the viewing window to ensure that there was no obvious particle agglomeration.

[0052] After mixing, the bottom discharge valve of the mixing kettle is opened, and the material is conveyed to the feed port of the twin-screw extruder. The barrel temperature of the twin-screw extruder is set to 145℃, and the temperature is gradually increased from the feed section to the discharge section. The screw speed is 120r / min. Through strong shearing action, the material particles are further refined, and the montmorillonite flakes are initially peeled off. After continuous extrusion by the twin-screw extruder, the material enters the nano-grinding mill. Before starting the nano-grinding mill, the filling amount of grinding media is checked, the grinding pressure is set to 0.8MPa, and the number of cycles is 3. After grinding, the particle size of the material is controlled to be below 5um. The qualified material is diverted through the dual discharge ports. One part is directly conveyed to the extruder of the composite molding module through the insulated pipeline, and the other part enters the reaction tank for the preparation of prepreg.

[0053] Example 2, please refer to Figure 1 and Figure 3 One embodiment of the present invention is a high-temperature resistant annular rubber conveyor belt preparation system. The rubber melt in the raw material processing module enters the extruder in the composite molding module through the heat-insulated pipe. The rubber melt in the raw material processing module is diluted and mixed to form a rubber solution which enters the prepreg tank in the composite molding module.

[0054] The composite molding module includes prepreg treatment and extrusion molding. In the prepreg treatment, aramid canvas is passed through a prepreg tank with a tension of 60N. The prepreg tank contains modified rubber liquid with a solid content of 25%. It is immersed at 40°C for 20 seconds to allow small molecule rubber to penetrate into the fiber bundles. After drying at 100°C, a coating layer is formed, which provides a basis for subsequent vulcanization. The composite molding module is equipped with an unwinding device and two extruders. The unwinding device outputs aramid canvas and guides it between the two upper and lower extruders. One discharge pipe of the nano-grinding machine is directly connected to the hopper of the extruder, and the modified rubber melt is quantitatively delivered by a gear pump.

[0055] Further, modified rubber melt from the raw material processing module is introduced into the reaction vessel. Toluene is added at a mass ratio of 3:1 to the rubber melt, followed by 3% (by mass) of the vulcanizing agent DCP. The mixture is then placed into the reaction vessel at 45°C, with the pressure maintained at 0.1 MPa. The stirring speed is set to 300 r / min and stirring is continued for 3 hours. During this time, the operator observes the state of the rubber solution through a viewing window. After stirring, the rubber solution is filtered through a stainless steel filter to remove undissolved rubber particles and impurities, ultimately yielding a rubber solution with a solid content of 25%. The solution is then transported to the pre-impregnation tank through an insulated conveying pipeline. The inner wall of the pipeline is polished to prevent residual rubber solution from forming scale.

[0056] Example 3, please refer to Figure 1 , Figure 3 and Figure 6 One embodiment of the present invention is a high-temperature resistant annular rubber conveyor belt preparation system. The rubber melt in the raw material processing module enters the extruder in the composite molding module through the heat-insulated pipe. The rubber melt in the raw material processing module is diluted and mixed to form a rubber solution which enters the prepreg tank in the composite molding module.

[0057] The composite molding module includes prepreg treatment and extrusion molding. Prepreg treatment involves passing aramid canvas through a prepreg tank with a tension of 60N. The prepreg tank contains modified rubber liquid with a solid content of 25%. The canvas is immersed at 40°C for 20 seconds, allowing small molecule rubber to penetrate into the fiber bundles. After drying at 100°C, a coating layer is formed, providing a basis for subsequent vulcanization. Extrusion molding involves the prepreg aramid canvas entering between two extruders. The two extruders uniformly wrap the modified rubber melt at 140°C on both sides of the canvas under a pressure of 1.5MPa, forming a three-layer structure of rubber, canvas, and rubber.

[0058] The composite molding module is equipped with an unwinding device and two extruders. The unwinding device outputs aramid canvas and guides the aramid canvas into the middle of the two upper and lower extruders. One discharge pipe of the nano-grinding machine is directly connected to the hopper of the extruder, and the modified rubber melt is quantitatively delivered through a gear pump.

[0059] Further, the cleanliness of the prepreg tank was confirmed, and the prepared rubber solution was injected into the prepreg tank. The aramid canvas was installed on the unwinding device, the tension was set to 60N, and the unwinding motor was started, so that the aramid canvas entered the prepreg tank through the guide roller at a speed of 1.2m / min. After soaking for 20 seconds, it was discharged and then dried for 5 minutes to form a uniform coating layer. The prepreg aramid canvas was aligned with the position by the steering roller and vertically entered the middle of the upper and lower extruders. The extruder die head was preheated to 140℃, and the composite pressure was set to 1.5MPa. The flow rate of the upper and lower melt was synchronously controlled by the melt pump to ensure that the rubber melt evenly wrapped both sides of the canvas. Then the upper and lower extruders injected the rubber melt into both sides of the aramid canvas to form a three-layer structure of rubber, canvas and rubber. The semi-finished product after molding was conveyed to the conveyor belt by the traction roller and then smoothly entered the microwave vulcanizing box of the gradient vulcanizing module.

[0060] Example 4, please refer to Figure 1 and Figure 4 The present invention provides an embodiment of a high-temperature resistant annular rubber conveyor belt preparation system. The semi-finished product extruded by the composite molding module is transported to the gradient vulcanization module by the conveyor belt. The gradient vulcanization module includes preheating, vulcanization and shaping. Preheating activates the rubber molecular chains. The semi-finished product is transported to the first microwave vulcanization box. Through heating and pressure, the molecular chains in the modified rubber matrix are changed from a frozen state to an active state. At the same time, the small rubber molecules of the pre-impregnated rubber layer penetrate into the gaps of the aramid canvas fibers, creating molecular contact conditions for the subsequent cross-linking reaction and avoiding local overheating and uneven cross-linking caused by direct high temperature.

[0061] Vulcanization is the process by which the rubber molecular chains and the vulcanizing agent rapidly cross-link and react under high temperature and high pressure when the semi-finished product is transported to the second stage microwave vulcanizing box, forming a three-dimensional network structure.

[0062] The shaping process involves transporting the finished product to the third stage microwave vulcanizing chamber to eliminate internal stress. Through slow cooling and pressure gradient release, the internal stress caused by rapid cross-linking in the vulcanizing stage is relieved, the three-dimensional network structure is stabilized, and the dimensional shrinkage after cooling is reduced. At the same time, the bond between the aramid canvas and the rubber interface is made more stable, avoiding interlayer delamination caused by stress concentration during subsequent use.

[0063] Furthermore, the semi-finished product after composite molding is transported to the gradient vulcanization module via a conveyor belt. The conveyor belt speed is consistent with the molding speed. It first enters the first microwave vulcanization chamber, where the temperature is set at 170℃, the pressure at 1.6MPa, the microwave power at 30kW, and the processing time at 3min. This process changes the molecular chains in the modified rubber matrix from a frozen state to an active state, allowing the small rubber molecules in the pre-impregnated rubber layer to penetrate into the gaps between the aramid canvas fibers. During this process, the surface temperature is monitored by an infrared thermometer to ensure that the temperature fluctuations are normal.

[0064] Then it enters the second stage microwave vulcanizing chamber, with the temperature set at 180℃, the pressure at 2.0MPa, the microwave power increased to 45kW, and the processing time at 6min. At this time, a cross-linking reaction occurs. In the cross-linking reaction, the molecular chains in the modified rubber matrix react with the vulcanizing agent oxide and are connected to each other through covalent bonds to form a stable three-dimensional network structure, which transforms the rubber from a plastic material into an elastomer, improving tensile strength, heat resistance and deformation resistance.

[0065] Finally, it enters the third stage microwave vulcanizing chamber, where the temperature is set at 160℃, the pressure at 1.5MPa, the microwave power is reduced to 25kW, and the processing time is 3 minutes. This eliminates the internal stress of the rubber conveyor belt, making the bond between the aramid canvas and the rubber interface more stable.

[0066] Example 5, please refer to Figure 1 One embodiment of the present invention provides a high-temperature resistant annular rubber conveyor belt preparation system. The intelligent quality inspection module is equipped with a phased array ultrasonic instrument, an electronic universal testing machine, and a thermal aging test chamber. The phased array ultrasonic instrument is installed on the conveyor path at the discharge end of the gradient vulcanization module. The electronic universal testing machine is installed downstream of the ultrasonic instrument and is equipped with a 500kN high-precision tensile sensor. Standard samples are cut from the conveyor belt using an automatic sampling device to test key mechanical properties. The thermal aging test chamber is located at the end of the conveyor belt and can simulate a high-temperature environment to conduct a 1000-hour thermal aging test at 200°C.

[0067] Furthermore, the phased array ultrasonic instrument is installed along the conveyor belt at the discharge end of the gradient vulcanization module. The phased array ultrasonic instrument is started, the scanning width is set to 2m and the sampling interval is 0.5mm. After the equipment is preheated for 30 minutes, ultrasonic waves are emitted across the entire width of the conveyor belt. The reflected signals are digitally processed to generate tomographic images. When bubbles larger than 0.5mm and delamination larger than 1mm are detected, the system automatically marks the position, places the unqualified products into the recycling bin, stops manufacturing, and reminds the operator to check the problem and adjust the parameters through audible and visual alarms.

[0068] The conveyor belt that passes the ultrasonic test is sampled by an automatic sampling device. Three sets of parallel samples are taken every 10 meters. The samples are transferred to the electronic universal testing machine by a robotic arm. The electronic universal testing machine is set with a tensile rate of 50 mm / min and a clamping force of 10 kN to test the tensile strength and joint peel strength. The tensile strength is greater than 18 MPa and the joint peel strength is greater than 8 kN / m to be qualified. Unqualified products are placed in the recycling bin, and manufacturing is stopped at the same time to check the problems and adjust the parameters.

[0069] Three groups were randomly selected from the samples that passed the mechanical property test and placed in a thermal aging test chamber. The temperature of the thermal aging test chamber was set to 200℃, and then nitrogen was introduced to expel oxygen. The test duration was set to 1000 hours. After aging, the samples were cooled to room temperature and tested again by an electronic universal testing machine. A tensile strength retention rate greater than 14.4 MPa was considered qualified. Unqualified products were placed in a recycling box, and manufacturing was stopped. Problems were investigated and parameters were adjusted. The thermal aging test chamber can evaluate the thermo-oxidative aging stability of materials and provide key verification data for the high-temperature resistance performance of products.

[0070] Comparative Example 1: A high-temperature resistant annular rubber conveyor belt preparation system. 70 parts of EPDM rubber and 15 parts of aramid short fibers are added to an inert gas-protected mixing kettle. The mixing kettle is heated to 130°C and maintained at a pressure of 0.7 MPa for 35 minutes. After mixing, the material is discharged from the mixing kettle and enters a twin-screw extruder. The twin-screw extruder shears and extrudes the material into a nano-grinding mill for grinding. The grinding is repeated 3 times to ensure that the filler particle size is less than 5 μm, thus obtaining a modified rubber melt.

[0071] To prepare the prepreg solution, the rubber melt produced by the raw material processing module is taken, and toluene is added at a mass ratio of 3:1 to the rubber melt. Then, 3% of the melt mass of vulcanizing agent is added and put into a reaction tank at 45°C. The mixture is stirred at 300 r / min for 3 hours. After filtration, a rubber solution with a solid content of 25% is obtained and transported to the prepreg tank. Then, aramid canvas is installed on the unwinding device, and the canvas passes through the prepreg tank at a speed of 1.2 m / min. The temperature of the rubber solution is 40°C. After impregnation for 20 seconds, it is dried for 5 minutes to form a rubber coating layer. The prepreg canvas enters between the upper and lower extruders. Modified rubber melt at 140°C is introduced into the extruder, and the pressure is set to 1.5 MPa. The flow rate is controlled by the melt pump so that the melt evenly wraps both sides of the canvas, forming a three-layer structure of rubber, canvas, and rubber.

[0072] The semi-finished product after composite molding is conveyed to the gradient vulcanization module via a conveyor belt. First, it enters the first microwave vulcanization chamber, where the temperature is set at 170℃, the pressure at 1.6MPa, and the microwave power at 30kW, and it is processed for 3 minutes. Then, it enters the second microwave vulcanization chamber, where the temperature is set at 180℃, the pressure at 2.0MPa, and the microwave power is increased to 45kW, and it is processed for 6 minutes. Finally, it enters the third microwave vulcanization chamber, where the temperature is set at 160℃ and the pressure at 1.5MPa, and the microwave power is reduced to 25kW, and the processing time is 3 minutes. Finally, the modified annular rubber conveyor belt is obtained.

[0073] Comparative Example 2: A high-temperature resistant annular rubber conveyor belt preparation system. Nano-montmorillonite is modified by mixing nano-montmorillonite and silane coupling agent KH550 at a mass ratio of 10:1 in a mixer. The mixture is stirred at 80℃ and 1500 r / min for 2 hours to obtain modified nano-montmorillonite. 70 parts of EPDM rubber and 30 parts of modified nano-montmorillonite are then added to an inert gas-protected mixing kettle. The mixing kettle is heated to 130℃ and maintained at a pressure of 0.7 MPa for 35 minutes. After mixing, the material is discharged from the mixing kettle into a twin-screw extruder. The twin-screw extruder shears and extrudes the material into a nano-grinding mill for grinding. The grinding process is repeated three times to ensure the filler particle size is less than 5 μm, resulting in modified rubber melt.

[0074] To prepare the prepreg solution, the rubber melt produced by the raw material processing module is taken, and toluene is added at a mass ratio of 3:1 to the rubber melt. Then, 3% of the melt mass of vulcanizing agent is added and put into a reaction tank at 45°C. The mixture is stirred at 300 r / min for 3 hours. After filtration, a rubber solution with a solid content of 25% is obtained and transported to the prepreg tank. Then, aramid canvas is installed on the unwinding device, and the canvas passes through the prepreg tank at a speed of 1.2 m / min. The temperature of the rubber solution is 40°C. After impregnation for 20 seconds, it is dried for 5 minutes to form a rubber coating layer. The prepreg canvas enters between the upper and lower extruders. Modified rubber melt at 140°C is introduced into the extruder, and the pressure is set to 1.5 MPa. The flow rate is controlled by the melt pump so that the melt evenly wraps both sides of the canvas, forming a three-layer structure of rubber, canvas, and rubber.

[0075] The semi-finished product after composite molding is conveyed to the gradient vulcanization module via a conveyor belt. First, it enters the first microwave vulcanization chamber, where the temperature is set at 170℃, the pressure at 1.6MPa, and the microwave power at 30kW, and it is processed for 3 minutes. Then, it enters the second microwave vulcanization chamber, where the temperature is set at 180℃, the pressure at 2.0MPa, and the microwave power is increased to 45kW, and it is processed for 6 minutes. Finally, it enters the third microwave vulcanization chamber, where the temperature is set at 160℃ and the pressure at 1.5MPa, and the microwave power is reduced to 25kW, and the processing time is 3 minutes. Finally, the modified annular rubber conveyor belt is obtained.

[0076] Performance testing

[0077] Test 1 Tensile strength test: The samples prepared in Example 1 and Comparative Examples 1-2 were tested by a universal electronic tensile testing machine under constant temperature and humidity conditions, and the tensile strength was calculated.

[0078] Test 2: Joint peel strength test: The samples prepared in Example 1 and Comparative Examples 1-2 were tested by a universal electronic tensile testing machine under constant temperature and humidity conditions, and the joint peel strength was calculated.

[0079] Test 3 Thermal stability test: The samples prepared in Example 1 and Comparative Examples 1-2 were tested using a thermogravimetric analyzer to calculate the weight change of the samples during the heating process. The test temperature was 25-500℃.

[0080] Table 1 Test results of sample performance testing

[0081] Example Tensile strength (MPa) Joint peel strength (kN / m) Thermal weight loss rate (%) Example 1 19.15 10.22 4.25 Comparative Example 1 15.63 7.02 8.62 Comparative Example 2 14.39 6.57 10.35

[0082] Summary and Analysis

[0083] In terms of tensile strength, Example 1 (19.15 MPa) improved by 22.5% and 33.1% compared with Comparative Example 1 (15.63 MPa) and Comparative Example 2 (14.39 MPa), respectively. This was due to the synergistic reinforcing effect of nano-montmorillonite and aramid fiber in the raw material processing module, which solved the problem of mechanical property decay of traditional materials at high temperature.

[0084] Regarding the joint peel strength, Example 1 (10.22kN / m) improved by 45.6%-55.6% compared to the comparative example, which confirms the deep wetting of rubber and canvas and the uniform cross-linking effect of gradient vulcanization in the composite molding module, overcoming the defect of weak interfacial bonding of traditional joints.

[0085] Regarding the thermal weight loss rate, Example 1 (4.25%) was 49.3% of Comparative Example 1 and 41.0% of Comparative Example 2. This is attributed to the stable three-dimensional network structure constructed by gradient sulfidation and the barrier effect of montmorillonite, which greatly improved the material's resistance to thermal degradation.

[0086] In summary, this invention achieves a simultaneous leap in tensile strength, interfacial bonding force, and thermal stability, solving the problems of rapid thermo-oxidative aging and significant strength decay caused by uneven component dispersion in traditional rubber materials under high-temperature conditions, and providing a more reliable solution for conveyor belt applications under high-temperature conditions.

[0087] Working principle: First, the operator melts and blends EPDM rubber, modified nano-montmorillonite, and aramid short fibers under inert gas protection. The components are then uniformly dispersed by twin-screw shearing and nano-grinding. Under the action of silane coupling agent, montmorillonite is intercalated and exfoliated to form a three-dimensional mesh structure, which improves the heat barrier performance.

[0088] Then, the aramid canvas is impregnated and dried in a pre-impregnation tank to form a coating layer. Then, the modified rubber melt is compounded onto both sides of the canvas through upper and lower extruders to form a three-layer structure of rubber, canvas and rubber. Then, the preheating and activation of molecular chains, vulcanization to form a three-dimensional cross-linked network structure and shaping to eliminate internal stress are completed in three microwave vulcanization boxes in sequence to enhance structural stability.

[0089] Finally, the vulcanized conveyor belt products enter the intelligent quality inspection module. The intelligent quality inspection module verifies defects, strength and heat resistance in real time through ultrasonic flaw detection, mechanical testing and thermal aging test to ensure that the products meet the requirements of high-temperature working conditions.

[0090] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A high-temperature resistant annular rubber conveyor belt manufacturing system, comprising a raw material processing module, a composite molding module, a gradient vulcanization module, and an intelligent quality inspection module, characterized in that: The raw material processing module provides a modified rubber matrix to the composite molding module, and the semi-finished product of the composite molding module is conveyed to the gradient vulcanization module. The discharge end of the gradient vulcanization module is equipped with an intelligent quality inspection module. The raw material processing module includes melt blending and intercalation reactions; The melt blending process involves melting and mixing EPDM rubber, modified nano-montmorillonite, and aramid short fibers in a mixing kettle protected by an inert gas at 130°C and 0.7 MPa. The stirring paddle in the mixing kettle is started, the speed is set to 70 r / min, and the stirring is carried out for 35 min to fully mix the EPDM rubber, modified nano-montmorillonite, and aramid short fibers. The intercalation reaction is that modified montmorillonite, under the action of shear force and silane coupling agent, peels off layers and inserts between rubber molecular chains to form a modified rubber matrix.

2. The high-temperature resistant annular rubber conveyor belt manufacturing system according to claim 1, characterized in that: The rubber melt in the raw material processing module enters the extruder in the composite molding module through an insulated pipe. The rubber melt in the raw material processing module is diluted and mixed to form a rubber solution, which then enters the prepreg tank in the composite molding module. The composite molding module includes prepreg treatment and extrusion molding; Pre-impregnation involves passing aramid canvas through a pre-impregnation bath with a tension of 60N. The pre-impregnation bath contains modified rubber solution with a solid content of 25%. The canvas is impregnated at 40°C for 20 seconds, during which small molecule rubber molecules gradually penetrate into the fiber bundles. After drying at 100°C, a coating layer is formed. Extrusion molding involves feeding pre-impregnated aramid canvas between two extruders. The two extruders then uniformly coat both sides of the canvas with 140°C modified rubber melt under a pressure of 1.5 MPa, forming a three-layer structure of rubber, canvas, and rubber.

3. The high-temperature resistant annular rubber conveyor belt manufacturing system according to claim 2, characterized in that: The rubber melt is dissolved and mixed to form a rubber solution. Toluene solution is added at a ratio of 3:1 to rubber melt, followed by the addition of a vulcanizing agent. After dissolving in a reaction tank at 45°C for 3 hours, the solution is filtered through a screen to obtain a rubber solution with a solid content of 25%. The rubber solution with a solid content of 25% enters the prepreg tank in the prepreg treatment through a transmission pipeline. Another part of the rubber melt in the raw material processing module enters the upper and lower extruders through insulated pipelines. The extruders are started, the screw rotates at 200 r / min, and the barrel temperature is set to 150°C. The rubber melt is sheared, kneaded, and plasticized evenly, forming a melt with stable fluidity after 15 minutes.

4. The high-temperature resistant annular rubber conveyor belt manufacturing system according to claim 1, characterized in that: The semi-finished product extruded by the composite molding module is transported to the gradient vulcanization module by a conveyor belt. The gradient vulcanization module includes preheating, vulcanization, and setting. Preheating activates the rubber molecular chains. The semi-finished product is transported to the first microwave vulcanizing chamber, where the temperature is set at 170°C and the pressure at 1.6 MPa. The modified rubber matrix is ​​heated and pressurized, and the molecular chains change from frozen to active within 3 minutes. Vulcanization involves conveying the material to the second stage microwave vulcanizing chamber, where the temperature is set at 180℃ and the pressure at 2.0MPa. Within 6 minutes, the rubber molecular chains and vulcanizing agent rapidly cross-link to form a stable three-dimensional network structure. The final shaping process involves transporting the finished product to the third stage microwave vulcanizing chamber, where the temperature is set at 160℃ and the pressure at 1.5MPa. The temperature is then reduced in three stages over three minutes, with each stage decreasing by 5℃, and the pressure gradually decreasing from 1.5MPa to atmospheric pressure.

5. The high-temperature resistant annular rubber conveyor belt manufacturing system according to claim 4, characterized in that: During the preheating stage, the conveyor belt blank is driven by a servo motor to be conveyed to the first microwave vulcanizing box. The silicone pressure roller driven by the hydraulic cylinder at the top of the box is attached to the surface of the blank to preheat the rubber conveyor belt. The blank enters the second microwave vulcanizing box, and the hydraulic pressurizing devices on both sides are activated to apply pressure to the rubber conveyor belt through the honeycomb-shaped ventilated pressure plate to complete the crosslinking reaction.

6. The high-temperature resistant annular rubber conveyor belt manufacturing system according to claim 1, characterized in that: The intelligent quality inspection module is equipped with a phased array ultrasonic instrument, an electronic universal testing machine, and a thermal aging test chamber. The phased array ultrasonic instrument is installed on the conveyor path at the discharge end of the gradient vulcanization module. The electronic universal testing machine is installed downstream of the ultrasonic instrument and is equipped with a 500kN high-precision tensile sensor. Standard samples are cut from the conveyor belt through an automatic sampling device to test key mechanical properties. The thermal aging test chamber is located at the end of the conveyor belt and can simulate a high-temperature environment to conduct a 1000-hour thermal aging test at 200℃.

7. The high-temperature resistant annular rubber conveyor belt manufacturing system according to claim 1, characterized in that: The raw material processing module is equipped with a mixing kettle, a twin-screw extruder, and a nano-grinding mill. The bottom outlet of the mixing kettle is connected to the inlet of the twin-screw extruder. The outlet of the twin-screw extruder is connected to the inlet of the nano-grinding mill through a high-pressure insulated pipe. The nano-grinding mill has two outlets, one of which is connected to the reaction tank and the other of which is connected to the extruder in the composite module.

8. The high-temperature resistant annular rubber conveyor belt manufacturing system according to claim 1, characterized in that: The composite molding module is equipped with an unwinding device and two extruders. The unwinding device outputs aramid canvas and guides the aramid canvas into the middle of the two upper and lower extruders. One discharge pipe of the nano-grinding machine is directly connected to the hopper of the extruder, and the modified rubber melt is quantitatively delivered by a gear pump.

9. A method for preparing a high-temperature resistant annular rubber conveyor belt, adapted to the high-temperature resistant annular rubber conveyor belt preparation system according to any one of claims 1-8, characterized in that: The method includes the following steps: S1. Raw material processing: First, the nano-montmorillonite is modified by adding nano-montmorillonite and silane coupling agent KH550 into a mixer at a mass ratio of 10:1 and stirring at 80℃ and 1500r / min for 2 hours to obtain modified nano-montmorillonite. S2. Mixing and Kneading: Then, 70 parts of EPDM rubber, 30 parts of modified nano montmorillonite and 15 parts of aramid short fiber are put into an inert gas protected mixing kettle. The mixing kettle is heated to 130℃ and maintained at a pressure of 0.7MPa. The mixture is mixed for 35 minutes. After the mixing is completed, the material is discharged from the mixing kettle and enters a twin-screw extruder. The twin-screw extruder shears and extrudes the material into a nano mill for grinding. The grinding is repeated 3 times to ensure that the filler particle size is less than 5μm, and the modified rubber melt is obtained. S3. Solution preparation: Prepare pre-impregnated rubber solution by taking the rubber melt produced by the raw material processing module, adding toluene at a mass ratio of 3:1 to toluene and adding 3% of the melt mass of vulcanizing agent, and putting it into a reaction tank at 45°C. Stir at 300 r / min for 3 hours. After filtration, a rubber solution with a solid content of 25% is obtained and transported to the pre-impregnated rubber tank. S4. Extrusion Molding: The aramid canvas is installed on the unwinding device, and the canvas passes through the pre-impregnation tank at a speed of 1.2 m / min. The temperature of the adhesive is 40℃. After impregnation for 20 seconds, it is dried for 5 minutes to form a rubber coating layer. The pre-impregnated canvas enters between the upper and lower extruders. Modified rubber melt at 140℃ is introduced into the extruder, and the pressure is set to 1.5 MPa. The flow rate is controlled by the melt pump. The upper and lower symmetrically arranged extruders extrude the rubber melt synchronously and bond it to both sides of the canvas at a pressure of 1.5 MPa.

10. The method for preparing a high-temperature resistant annular rubber conveyor belt according to claim 9, characterized in that: The method further includes the following steps: S5. Gradient vulcanization: The semi-finished product after composite molding is conveyed to the gradient vulcanization module via a conveyor belt. First, it enters the first microwave vulcanization chamber, with the temperature set at 170℃, the pressure at 1.6MPa, and the microwave power at 30kW, and is processed for 3 minutes. Then, it enters the second microwave vulcanization chamber, with the temperature set at 180℃, the pressure at 2.0MPa, and the microwave power increased to 45kW, and is processed for 6 minutes. Finally, it enters the third microwave vulcanization chamber, with the temperature set at 160℃ and the pressure at 1.5MPa, and the microwave power reduced to 25kW, and the processing time is 3 minutes. S6 Intelligent Quality Inspection: After vulcanization, the conveyor belt products enter the intelligent quality inspection module. First, they are fully scanned by a phased array ultrasonic instrument to identify defects such as bubbles and delamination. When the defect size is greater than 0.5mm, it is marked as unqualified. Then, samples are taken every 10m and the tensile strength and joint peel strength are tested by an electronic universal testing machine. At the same time, 3 sets of samples are placed in a heat aging test chamber and aged at 200℃ for 1000h. The tensile strength and joint peel strength are then retested.

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