Foam forming process for elastic rotating body

Abstract

The invention relates to a process for realizing uniform foaming of an elastic rotating body through temperature gradient control, in particular to an elastic rotating body foaming forming process which comprises the following steps: S1, raw material pretreatment and internal mixing: adopting a blend of POE (Polyolefin Elastomer) and EPDM (Ethylene-Propylene-Diene Monomer) as a main body material, mixing POE and EPDM according to a mass ratio of 6: 4-8: 2, and carrying out extrusion molding; adding 3%-15% of an anti-shrinking agent, 8%-20% of talcum powder and 5%-12% of calcium carbonate as fillers, and mixing and plasticizing for 8-12 minutes through an internal mixer at the temperature of 80-100 DEG C and the rotor rotating speed of 30-50 rpm. According to the foaming forming process of the elastic rotating body, the shaping pipe and the built-in heating pipe are arranged in the middle of the mold cavity, so that the temperature of the middle of the mold cavity is 1-3 DEG C higher than that of the upper and lower areas, and therefore, an accurate axial temperature gradient is formed, the decomposition rate of a foaming agent and the material curing process are effectively balanced, and shrinkage deformation caused by uneven temperature is inhibited.

Description

Technical Field

[0001] The invention relates to a process for achieving uniform foaming of an elastic rotating body through temperature gradient control, and in particular to a foaming molding process of an elastic rotating body. Background Art

[0002] The elastic rotator is a key component of a guardrail, and its formulation, production process, and equipment are crucial. However, there are few technical reports on elastic rotators, both domestically and internationally. The elastic rotator is made of either ethylene vinyl acetate (EVA) or flexible polyurethane. The mass of a single elastic rotator ranges from 1 to 10 kg, so the EVA shot size needs to be within this range. Current foaming processes cannot achieve this large shot size in one go. The manufacturing process involves first creating a semicircular mold, then foaming the selected EVA material to obtain a semicircular blank. Two semicircular blanks are then placed in a special mold, heated, and pressed into a single piece, ultimately yielding the elastic rotator.

[0003] However, in the traditional elastic rotating body foaming process, uniform heating of the mold or external heat source radiation is often used, resulting in large differences in the curing rates of the inner and outer layers of the material. The bubbles generated during the decomposition of the foaming agent may be unevenly distributed in the foam body, causing bubble collapse and uneven density. Summary of the Invention

[0004] The content of this application is used to briefly introduce concepts that will be described in detail in the detailed description section below. The content of this application is not intended to identify key features or essential features of the technical solution for which protection is sought, nor is it intended to limit the scope of the technical solution for which protection is sought.

[0005] The purpose of the present invention is to provide a foaming molding process for an elastic rotating body to solve the problem that the heating method of the existing elastic rotating body mold will lead to different curing rates of the inner and outer layers of the material and cannot ensure the uniformity of the decomposition of the foaming agent.

[0006] To achieve the above object, the present invention provides the following technical solution: a foaming molding process for an elastic rotating body, comprising the following steps:

[0007] S1. Raw material pretreatment and mixing: POE and EPDM (ethylene propylene diene monomer) blends are used as the main materials, mixed at a mass ratio of POE:EPDM = 6:4-8:2, and 3%-15% anti-shrinkage agent, 8%-20% talc powder, and 5%-12% calcium carbonate are added as fillers. Mix and plasticize in an internal mixer at 80-100°C and a rotor speed of 30-50 rpm for 8-12 minutes.

[0008] S2, Plasticization and Injection: The granulated material is placed in the barrel and plasticized under segmented temperature control (70-80°C at the front end, 85-95°C in the middle, and 90-100°C at the end). It is then injected into the mold cavity, which is vacuumed to ≤0.08MPa, at an injection speed of ≥200mm / s and a pressure of ≥65MPa.

[0009] S3. Foaming and shaping: The mold cavity temperature is maintained at 160-190°C through the upper and lower heating tubes of the mold, and the foaming agent is fully decomposed with a holding time of 600-1200 seconds. A shaping tube 1 is set in the middle of the mold cavity, and the internal heating tube 4 is set to make the middle temperature 1-3°C higher than the upper and lower areas of the mold cavity, forming a local temperature gradient to suppress shrinkage and deformation.

[0010] S4, mold cooling: After foaming is completed, the mold is gradually cooled by water cooling or air cooling medium. In the first stage, it is cooled to 100℃ at a rate of ≥10℃ / min, and in the second stage, it is naturally cooled to room temperature to fix the foam structure;

[0011] S5. Post-processing and inspection: The demoulded product is subjected to surface trimming, plasma polishing or hydrophobic coating, and the cell uniformity is detected by X-ray and the elastic recovery rate is verified by tensile testing.

[0012] Preferably, in step S1, the mixture after internal mixing is tableted at 45-65° C. for 5-8 minutes in an open mixer, and the granulated particle size is 3-5 mm.

[0013] Preferably, during the injection phase of step S2, the injection speed is dynamically adjusted: in the initial phase, 80% of the mold cavity volume is filled at 200-300 mm / s, and the remaining 20% ​​is switched to a low-speed feeding of 50-100 mm / s.

[0014] Preferably, in step S3, the upper and lower heating tubes are resistance heating tubes or carbon fiber heating tubes, the distance between the heating tubes and the mold cavity is 1-3 mm, and the surface of the mold cavity is sprayed with a chromium alloy wear-resistant heat-conductive layer with a thickness of 0.1-0.3 mm.

[0015] Preferably, the shaping tube is a composite structure, made of double-layer stainless steel, the inner layer is a high-temperature resistant and corrosion-resistant alloy, and the outer layer is a heat-insulating coating to accurately conduct the heat of the heating tube;

[0016] The diameter of the shaping tube is 110~140mm, the wall thickness is 2~5mm, and the inner wall is provided with a medium heating tube. The medium heating tube is vertically arrayed in the installation groove opened on the inner wall of the shaping tube. The outer walls of the two ends of the shaping tube are symmetrically provided with blocks with a height of 2~5mm. When the mold is closed, the blocks are embedded in the card grooves of the mold cavity to form an airtight structure.

[0017] Preferably, in step S3, the foaming agent is a compound system of azodicarbonamide (AC) and sodium bicarbonate, with a mass ratio of AC:sodium bicarbonate = 3:1-5:1, and the amount of the foaming agent added is 1%-5% of the total mass of the base material.

[0018] Preferably, in step S4, the water-cooling medium is silicone oil or ethylene glycol aqueous solution, the flow rate is ≥5m³ / h, the cooling water temperature is 10~25°C, and the first stage cooling time is ≤10 minutes.

[0019] Preferably, after cooling in step S4, a post-processing step is added: placing the product in an oven at 80-100° C. for heat treatment for 30-60 minutes, followed by plasma surface activation treatment with an activation power of 200-400 W and a treatment time of 5-10 minutes.

[0020] Preferably, an independent thermocouple sensor is further provided inside the shaping tube to monitor temperature deviation in real time and feed back to the PLC controller.

[0021] Preferably, the inner wall of the shaping tube is further provided with a bionic flow channel, which is a honeycomb-shaped flow channel to enhance the uniformity of heat medium circulation.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The elastic rotating body foaming molding process proposed in the present invention, by arranging a shaping tube and its built-in heating tube in the middle of the mold cavity, makes the temperature in the middle of the mold cavity 1~3°C higher than the upper and lower areas, thereby forming a precise axial temperature gradient, effectively balancing the decomposition rate of the foaming agent and the curing process of the material, and suppressing shrinkage deformation caused by uneven temperature. The inner wall of the shaping tube is designed as a honeycomb-like flow channel, which enhances the circulation uniformity of the heat medium and reduces the risk of local overheating. In addition, with the application of a chromium alloy wear-resistant heat-conducting layer, the surface temperature fluctuation of the mold cavity is controlled within ±1°C, significantly improving the uniformity of the bubble distribution.

[0024] 2. The elastic rotating body foaming molding process proposed in the present invention quickly fills 80% of the volume of the mold cavity through high-speed injection and then switches to low-speed feeding, effectively reducing the generation of turbulent bubbles by 80%, and reducing the scrap rate from 15% in the traditional process to ≤5%. In addition, piezoelectric pressure sensors are installed at the injection machine nozzle and the mold inlet to monitor injection pressure fluctuations in real time; the molding tube is divided into multiple axial heating zones, and a thermocouple sensor is embedded in each zone to collect temperature data in real time and analyze it in conjunction with the pressure signal. The zoned response of the pressure and thermocouple sensors ensures that the foaming agent decomposes in the optimal temperature zone, avoiding the occurrence of density stratification. This process achieves dynamic stabilization of the temperature gradient under injection pressure fluctuations, significantly improving the foaming uniformity and the qualified rate of the product.

[0025] 3. The elastic rotating body foaming process proposed in this invention utilizes dynamic injection speed adjustment and high shear rate technology to enhance the separation of the foaming agent from the base material. The foaming agent is concentrated around the sizing tube, which helps improve the foaming effect and ensures that the foaming agent decomposes within the optimal temperature range, thereby ensuring product quality and foaming uniformity. Controlling parameters such as injection pressure and mold vacuum avoids gas interference and uneven gas distribution, further reducing scrap rates.

[0026] 4. The elastic rotating body foaming process proposed in this invention utilizes PLC for precise temperature control, combined with a honeycomb-like flow channel design, to effectively enhance the uniformity of heat medium circulation, ensuring temperature fluctuations of ≤±0.5°C, thereby reducing energy consumption by approximately 30%. This technological innovation not only improves production efficiency but also brings significant energy savings to the production process, reducing production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings constituting a part of this application are used to provide a further understanding of this application and make other features, purposes and advantages of this application more apparent. The drawings and descriptions of the exemplary embodiments of this application are used to explain this application and do not constitute an improper limitation on this application.

[0028] In addition, throughout the drawings, the same or similar reference numerals represent the same or similar elements. It should be understood that the drawings are schematic and that the elements and components are not necessarily drawn to scale.

[0029] In the attached figure:

[0030] Figure 1 Schematic diagram of the shaping tube structure of the elastic rotating body foaming molding process of the present invention;

[0031] Figure 2 This is a schematic diagram of the expanded state of the inner wall of the shaping tube in the elastic rotating body foaming molding process of the present invention.

[0032] In the figure: 1. Molding tube; 2. Clamping block; 3. Mounting groove; 4. Middle heating tube; 5. Honeycomb-shaped flow channel. DETAILED DESCRIPTION

[0033] Embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although certain embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be construed as limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the present disclosure. It should be understood that the drawings and embodiments of the present disclosure are for illustrative purposes only and are not intended to limit the scope of protection of the present disclosure.

[0034] It should also be noted that, for ease of description, only the parts related to the invention are shown in the drawings. In the absence of conflict, the embodiments and features in the embodiments of the present disclosure may be combined with each other.

[0035] It should be noted that the concepts of "first" and "second" mentioned in this disclosure are only used to distinguish different devices, modules or units, and are not used to limit the order or interdependence of the functions performed by these devices, modules or units.

[0036] It should be noted that the modifications of "one" and "multiple" mentioned in the present disclosure are illustrative rather than restrictive, and those skilled in the art should understand that unless otherwise clearly indicated in the context, they should be understood as "one or more".

[0037] The names of the messages or information exchanged between multiple devices in the embodiments of the present disclosure are only used for illustrative purposes and are not used to limit the scope of these messages or information.

[0038] The present disclosure will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0039] See also Figure 1-2 , a foaming molding process for an elastic rotating body, comprising the following steps:

[0040] S1. Raw material pretreatment and mixing: POE and EPDM (ethylene propylene diene monomer) blends are used as the main materials, mixed at a mass ratio of POE:EPDM = 6:4-8:2, and 3%-15% anti-shrinkage agent, 8%-20% talc powder, and 5%-12% calcium carbonate are added as fillers. Mix and plasticize in an internal mixer at 80-100°C and a rotor speed of 30-50 rpm for 8-12 minutes.

[0041] S2, Plasticization and Injection: The granulated material is placed in the barrel and plasticized under segmented temperature control (70-80°C at the front end, 85-95°C in the middle, and 90-100°C at the end). It is then injected into the mold cavity, which is vacuumed to ≤0.08MPa, at an injection speed of ≥200mm / s and a pressure of ≥65MPa.

[0042] S3. Foaming and shaping: The mold cavity temperature is maintained at 160-190°C through the upper and lower heating tubes of the mold, and the foaming agent is fully decomposed with a holding time of 600-1200 seconds. A shaping tube 1 is set in the middle of the mold cavity, and the internal heating tube 4 is set to make the middle temperature 1-3°C higher than the upper and lower areas of the mold cavity, forming a local temperature gradient to suppress shrinkage and deformation.

[0043] S4, mold cooling: After foaming is completed, the mold is gradually cooled by water cooling or air cooling medium. In the first stage, it is cooled to 100℃ at a rate of ≥10℃ / min, and in the second stage, it is naturally cooled to room temperature to fix the foam structure;

[0044] S5. Post-processing and inspection: The demoulded product is subjected to surface trimming, plasma polishing or hydrophobic coating, and the cell uniformity is detected by X-ray and the elastic recovery rate is verified by tensile testing.

[0045] Furthermore, in step S1, the mixture after internal mixing is pressed into tablets at 45-65° C. for 5-8 minutes in an open mixer, and the granulated particle size is 3-5 mm.

[0046] Furthermore, during the injection phase of step S2, the injection speed is dynamically adjusted: in the initial phase, 80% of the mold cavity volume is filled at 200-300 mm / s, and the remaining 20% ​​is switched to a low-speed feeding of 50-100 mm / s.

[0047] Piezoelectric pressure sensors are installed at the injection machine nozzle and mold inlet to monitor injection pressure fluctuations in real time. The sizing tube (1) is divided into multiple axial heating zones, each embedded with a thermocouple sensor to collect real-time temperature data and analyze it in conjunction with the pressure signal. This zoning response of the pressure and thermocouple sensors ensures that the foaming agent decomposes within the optimal temperature zone, preventing density stratification.

[0048] During the injection phase, the mold runners guide the melt to create a directional flow effect. Due to its lower density than the melt, the foaming agent migrates and concentrates around the sizing tube 1 in the shear flow field. The injection speed is dynamically adjusted (initially 200-300 mm / s, later 50-100 mm / s). High shear rates (Re > 4000) enhance the separation of the foaming agent from the melt, allowing the concentration of the foaming agent in the concentrated area to reach 1.5-2 times that of the matrix material. Simultaneously, the mold cavity vacuum is controlled at ≤0.08 MPa to reduce gas interference and promote the migration of the foaming agent to the high-temperature area. The injection pressure (≥65 MPa) and the local high pressure of the sizing tube create a pressure gradient, forcing the foaming agent to preferentially nucleate near the sizing tube.

[0049] Because the foaming agent concentrates around the sizing tube 1, its concentration can reach 1.5 to 2 times that of the base material, enhancing the foaming effect and ensuring a more uniform foam structure in the final elastic rotating body, improving foaming uniformity. The mold cavity vacuum is controlled at ≤0.08 MPa, effectively reducing gas interference and preventing uneven gas distribution during melt flow. This ensures a relatively stable operating environment for the foaming agent, further enhancing its effectiveness. By controlling the vacuum level and shear flow field, the foaming agent is more easily migrated to the high-temperature area, helping it decompose at the optimal temperature. This ensures a stable foaming process, avoids density stratification, and improves product quality. The pressure gradient created by the injection pressure (≥65 MPa) and the local high pressure around the sizing tube 1 forces the foaming agent to preferentially nucleate near the sizing tube 1. This targeted nucleation effectively prevents excessive dispersion or uneven distribution of the foaming agent, ensuring stable and uniform foaming in the final product. Dynamic adjustment of injection speed and high shear rate helps to improve the separation of foaming agent and melt, improve the accuracy of the foaming process, thereby reducing the scrap rate and improving the product qualification rate and production efficiency.

[0050] Furthermore, in step S3, the upper and lower heating tubes are resistance heating tubes or carbon fiber heating tubes, the distance between the heating tubes and the mold cavity is 1-3 mm, and the surface of the mold cavity is sprayed with a chromium alloy wear-resistant heat-conductive layer with a thickness of 0.1-0.3 mm.

[0051] Furthermore, the shaping tube 1 is a composite structure, made of double-layer stainless steel, the inner layer is a high-temperature resistant and corrosion-resistant alloy, and the outer layer is a heat-insulating coating to accurately conduct the heat of the heating tube 4;

[0052] The diameter of the shaping tube 1 is 110~140mm, the wall thickness is 2~5mm, and the inner wall is provided with a medium heating tube 4. The medium heating tube 4 is vertically arrayed in the installation groove 3 opened on the inner wall of the shaping tube 1. The outer walls of the two ends of the shaping tube 1 are symmetrically provided with blocks 2. The height of the block 2 is 2~5mm. When the mold is closed, the block 2 is embedded in the groove of the mold cavity to form an airtight structure.

[0053] The card block 2 is embedded in the card slot of the mold cavity to form a good airtight structure, which effectively prevents gas leakage and ensures the gas stability during the foaming process, thereby improving the foaming quality and product consistency. The card block 2 and the card slot can also be set as an annular card block and card slot, and one end of the shaping tube 1 is connected to an external motor to drive the shaping tube 1 to rotate, which can effectively stir the injection material, help to evenly disperse the foaming agent, improve the uniformity of foaming, and avoid material deposition and uneven distribution. The rotation of the shaping tube 1 not only enhances the miscibility of the material, but also promotes the fluidity of the material, making the injection process smoother, reducing the risk of bubble aggregation and uneven foaming, thereby improving the quality of the product and the molding effect.

[0054] An independent thermocouple sensor is also provided inside the shaping tube 1 to monitor the temperature deviation in real time and feed it back to the PLC controller.

[0055] The inner wall of the shaping tube 1 is further provided with a bionic flow channel, which is a honeycomb-shaped flow channel 5 to enhance the uniformity of heat medium circulation.

[0056] The sizing tube 1 houses a central heating tube 4, which is vertically embedded in the mounting groove 3 and interacts with a honeycomb-shaped flow channel 5 with a depth of 1.2 to 2 mm. This creates an axial temperature gradient, effectively controlling the decomposition rate of the foaming agent to a deviation of ≤±5%. A built-in thermocouple sensor monitors the temperature in real time and feeds this data to a PLC controller, automatically adjusting the heating power to limit temperature fluctuations to within ±0.5°C. This reduces energy consumption by approximately 30% compared to traditional processes.

[0057] The combination of the intermediate heating tube 4 and precise PLC temperature control keeps the temperature around the sizing tube 1 1-3°C higher than the upper and lower areas of the mold cavity, accelerating the decomposition of the AC foaming agent. Furthermore, the honeycomb-like flow channel 5 enhances the uniform circulation of the heat medium, ensuring local temperature fluctuations of ≤±0.5°C, further ensuring that the deviation of the foaming agent decomposition rate is controlled within ±5%.

[0058] In addition, the gradient structure of the inner and outer cells of the shaped tube 1 promotes the rapid decomposition of the foaming agent in the high-temperature zone, forming high-density cells. The surface layer forms a dense layer due to rapid cooling, and the closed cell rate reaches ≥95%, greatly improving the wear resistance and compressive strength.

[0059] Furthermore, in step S3, the foaming agent is a compound system of azodicarbonamide (AC) and sodium bicarbonate, with a mass ratio of AC:sodium bicarbonate = 3:1-5:1, and the amount of the foaming agent added is 1%-5% of the total mass of the base material.

[0060] Furthermore, in step S4, the water-cooling medium is silicone oil or ethylene glycol aqueous solution, the flow rate is ≥5m³ / h, the cooling water temperature is 10~25°C, and the first stage cooling time is ≤10 minutes.

[0061] Furthermore, after cooling in step S4, a post-processing step is added: placing the product in an oven at 80-100° C. for heat treatment for 30-60 minutes, and then performing plasma surface activation treatment with an activation power of 200-400 W and a treatment time of 5-10 minutes.

[0062] The inventors arrived at the technical solution of the present invention through extensive experimentation and exploration. Upper and lower heating tubes maintain the mold cavity temperature at 160-190°C, combined with a 600-1200 second hold time to ensure sufficient decomposition of the foaming agent. A shaping tube 1 is positioned in the center of the mold cavity, along with an internal intermediate heating tube 4. This creates a temperature gradient in the center that is 1-3°C higher than that in the upper and lower zones, effectively suppressing shrinkage and deformation, ensuring uniform foaming, and ultimately, guaranteeing product quality.

[0063] The present invention is able to achieve the above-mentioned significant substantial characteristics and progressive effects. The reasons for this have been analyzed many times and are as follows: by arranging a shaping tube 1 and a built-in intermediate heating tube 4 in the middle of the mold cavity, the temperature in the middle of the mold cavity is made 1~3°C higher than that in the upper and lower areas, thereby forming a precise axial temperature gradient. This design effectively balances the decomposition rate of the foaming agent and the solidification process of the material, and suppresses the occurrence of shrinkage deformation. In addition, the design of the honeycomb-shaped flow channel 5 on the inner wall of the shaping tube 1 enhances the circulation uniformity of the heat medium and reduces the risk of local overheating. At the same time, in combination with the chromium alloy wear-resistant heat-conducting layer, the temperature fluctuation of the mold cavity surface is controlled within ±1°C, thereby significantly improving the uniformity of the distribution of the bubbles.

[0064] Example 1

[0065] Base material: POE:EPDM=7:3, talc 18%, calcium carbonate 10%, anti-shrinkage agent 8%;

[0066] Foaming agent: AC: sodium bicarbonate = 4:1, addition amount 3%;

[0067] The diameter of the shaping tube 1 is 130 mm, the middle temperature is 178°C, and the depth of the honeycomb flow channel 5 is 1.2 mm;

[0068] Injection speed: 250 mm / s in the initial stage, 80 mm / s in the feeding stage;

[0069] The cooling medium is ethylene glycol aqueous solution.

[0070] The elastic rotating body obtained in Example 1 has a density of 0.50 g / cm³ and a compression set of ≤6%.

[0071] Example 2

[0072] Base material: POE:EPDM=8:2, talc 12%, calcium carbonate 6%, anti-shrinkage agent 10%;

[0073] Foaming agent: AC: sodium bicarbonate = 5:1, added amount 4.5%;

[0074] The diameter of the shaping tube 1 is 120 mm, the middle temperature is 182°C, and the spacing of the honeycomb flow channels 5 is 15 mm;

[0075] Injection speed: 280 mm / s in the initial stage, 60 mm / s in the feeding stage;

[0076] Post-treatment: heat treatment at 90°C for 50 minutes, plasma activation power 350W.

[0077] The elastic rotating body obtained in Example 2 has a density of 0.38 g / cm³ and good wear resistance, with a mass loss of no more than 5 mg after 1000 cycles.

[0078] Example 3

[0079] Base material: POE:EPDM=6:4, talc 20%, calcium carbonate 12%, anti-shrinkage agent 5%;

[0080] Foaming agent: AC: sodium bicarbonate = 3:1, addition amount 2.5%;

[0081] The diameter of the shaping tube 1 is 140 mm, the middle temperature is 185°C, and the width of the honeycomb-shaped flow channel 5 is 2 mm;

[0082] Injection speed: 200mm / s throughout the entire process;

[0083] The cooling medium is silicone oil.

[0084] The elastic rotating body obtained in Example 3 has a density of 0.44 g / cm³, a bearing strength of ≥28 MPa, excellent fatigue resistance, and a deformation of less than 3% after 100,000 compression cycles.

[0085]

[0086] By optimizing various parameters during the foaming process, the present invention significantly shortens the molding cycle. For example, the molding cycle of Example 1 is 20 minutes, which is over 15% shorter than that of conventional processes, significantly improving production efficiency. Furthermore, due to the precise control of the foaming process, the quality of the final product is more stable, and the density deviation is kept within a relatively low range, further enhancing production accuracy.

[0087] In summary, the present invention achieves high-precision, high-performance, and low-energy production of elastic rotating body foam products through gradient temperature control of the molding tube, dynamic injection optimization, and coordinated design of the composite structure. This is particularly suitable for the manufacture of high-end elastic components for road traffic equipment. Examples demonstrate that this invention significantly outperforms traditional EVA substrate processes in terms of overall performance and has broad market application prospects.

[0088] The above descriptions are merely some preferred embodiments of the present disclosure and illustrate the underlying technical principles. Those skilled in the art should understand that the scope of the invention encompassed by the embodiments of the present disclosure is not limited to technical solutions formed by specific combinations of the aforementioned technical features. It also encompasses other technical solutions formed by any combination of the aforementioned technical features or their equivalents, without departing from the aforementioned inventive concept. For example, a technical solution formed by replacing the aforementioned features with (but not limited to) technical features with similar functions disclosed in the embodiments of the present disclosure.

Claims

1. A foaming process for an elastic rotating body, characterized in that: The steps include: S1. Raw material pretreatment and mixing: POE and EPDM (ethylene propylene diene monomer) blends are used as the main materials, mixed at a mass ratio of POE:EPDM = 6:4-8:2, and 3%-15% anti-shrinkage agent, 8%-20% talc powder, and 5%-12% calcium carbonate are added as fillers. Mix and plasticize in an internal mixer at 80-100°C and a rotor speed of 30-50 rpm for 8-12 minutes. S2, Plasticization and Injection: The granulated material is placed in the barrel and plasticized under segmented temperature control (70-80°C at the front end, 85-95°C in the middle, and 90-100°C at the end). It is then injected into the mold cavity, which is vacuumed to ≤0.08MPa, at an injection speed of ≥200mm / s and a pressure of ≥65MPa. S3, foaming and shaping: the mold cavity temperature is maintained at 160-190°C through the upper and lower heating tubes of the mold, and the foaming agent is fully decomposed with a heat preservation time of 600-1200s; a shaping tube (1) is set in the middle of the mold cavity, and a middle heating tube (4) is built in it to make the middle temperature 1-3°C higher than the upper and lower areas of the mold cavity, forming a local temperature gradient to suppress shrinkage deformation; S4, mold cooling: After foaming is completed, the mold is gradually cooled by water cooling or air cooling medium. In the first stage, it is cooled to 100℃ at a rate of ≥10℃ / min, and in the second stage, it is naturally cooled to room temperature to fix the foam structure; S5. Post-processing and inspection: The demoulded product is subjected to surface trimming, plasma polishing or hydrophobic coating, and the cell uniformity is detected by X-ray and the elastic recovery rate is verified by tensile testing.

2. The elastic rotating body foaming molding process according to claim 1, characterized in that: In step S1, the mixture after internal mixing is pressed into tablets at 45-65° C. for 5-8 minutes in an open mixer, and the granulated particle size is 3-5 mm.

3. The elastic rotating body foaming molding process according to claim 2, characterized in that: During the injection phase of step S2, the injection speed is dynamically adjusted: in the initial phase, 80% of the mold cavity volume is filled at 200-300 mm / s, and the remaining 20% ​​is switched to a low speed of 50-100 mm / s.

4. The elastic rotating body foaming molding process according to claim 3, characterized in that: In step S3, the upper and lower heating tubes are resistance heating tubes or carbon fiber heating tubes, the distance between the heating tubes and the mold cavity is 1-3 mm, and the surface of the mold cavity is sprayed with a chromium alloy wear-resistant heat-conductive layer with a thickness of 0.1-0.3 mm.

5. The elastic rotating body foaming molding process according to claim 4, characterized in that: The shaping tube (1) is a composite structure, made of double-layer stainless steel, the inner layer is a high-temperature resistant and corrosion-resistant alloy, and the outer layer is a heat-insulating coating to accurately conduct the heat of the heating tube (4); The shaping tube (1) has a diameter of 110-140 mm and a wall thickness of 2-5 mm. A middle heating tube (4) is provided on its inner wall. The middle heating tube (4) is arranged vertically in an installation groove (3) provided on the inner wall of the shaping tube (1). Clamping blocks (2) are symmetrically provided on the outer walls of both ends of the shaping tube (1). The height of the clamping blocks (2) is 2-5 mm. When the mold is closed, the clamping blocks (2) are embedded in the clamping groove of the mold cavity to form an airtight structure.

6. The elastic rotating body foaming molding process according to claim 5, characterized in that: In step S3, the foaming agent is a compound system of azodicarbonamide (AC) and sodium bicarbonate, with a mass ratio of AC:sodium bicarbonate = 3:1-5:1, and the amount of the foaming agent added is 1%-5% of the total mass of the base material.

7. The elastic rotating body foaming molding process according to claim 6, characterized in that: In step S4, the water-cooling medium is silicone oil or ethylene glycol aqueous solution, the flow rate is ≥5m³ / h, the cooling water temperature is 10-25°C, and the first-stage cooling time is ≤10 minutes.

8. The elastic rotating body foaming molding process according to claim 7, characterized in that: After cooling in step S4, a post-processing step is added: placing the product in an oven at 80-100° C. for heat treatment for 30-60 minutes, followed by plasma surface activation treatment with an activation power of 200-400 W and a treatment time of 5-10 minutes.

9. The elastic rotating body foaming molding process according to claim 8, characterized in that: An independent thermocouple sensor is also provided inside the shaping tube (1) to monitor temperature deviation in real time and feed back to the PLC controller.

10. The elastic rotating body foaming molding process according to claim 9, characterized in that: The inner wall of the shaped tube (1) is further provided with a bionic flow channel, which is a simulated honeycomb flow channel (5) to enhance the uniformity of heat medium circulation.

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