Automobile rubber sealing element and preparation method thereof

Abstract

The invention relates to the technical field of automobile parts, in particular to an automobile rubber sealing part and a preparation method thereof. A metal framework base material is stamped in a numerical control mode, and a framework blank is obtained by controlling deviation through a positioning pin; after being slightly roughened, the blank is phosphatized, coated with a special rubber prime coat adhesive and subjected to infrared drying; weighing the raw materials according to the ratio, feeding into an internal mixer by stages, and mixing at controlled temperature and speed to obtain a rubber compound; feeding the mixed rubber into a double-roller open mill to press a continuous rubber sheet in a step-by-step distance-adjusting manner; performing hydraulic cutting by a special cutting die to obtain a slightly large formed rubber sheet; sticking the molded film to the framework into a mold with a positioning boss, exhausting, boosting and vulcanizing to obtain a semi-finished product; feeding the semi-finished product into a hot air oven and introducing nitrogen for secondary vulcanization; and carrying out laser thickness measurement and visual inspection, packaging qualified products in an anti-static manner, and sealing in a corrugated carton. The framework precision and the rubber bonding strength are improved, and degumming is avoided; stable rubber material performance and uniform rubber sheet thickness are guaranteed, and material shortage is reduced; vulcanization displacement and bubbles are prevented, rubber oxidation and aging are inhibited, and the durability and stability of the product are improved.

Description

Technical Field

[0001] This invention relates to the field of automotive parts technology, specifically to an automotive rubber seal and its preparation method. Background Technology

[0002] Currently, the manufacturing process of traditional automotive rubber seals still suffers from numerous technical shortcomings, resulting in poor product quality stability and a high defect rate. In the skeleton processing stage, traditional stamping equipment often uses ordinary molds for positioning, lacking a precise deviation control mechanism. This leads to significant dimensional deviations in the stamped skeleton blanks, easily causing edge burrs and hole misalignment, making precise matching difficult during subsequent bonding with rubber. Furthermore, the surface treatment of the skeleton often involves only simple phosphating without targeted micro-roughening, resulting in weak adhesion between the phosphating layer and the skeleton substrate. Additionally, adhesive application relies heavily on manual operation, leading to uneven coating thickness and rough control of drying process parameters. This results in insufficient bonding strength between the rubber and the skeleton, making long-term use prone to delamination.

[0003] In the rubber compound processing stage, traditional mixing processes suffer from low raw material ratio accuracy and disordered control of mixing temperature and speed, often resulting in uneven dispersion of compounding agents and large fluctuations in the performance of the compounded rubber. Rubber sheeting often uses ordinary open mills for rough calendering, with insufficient roller gap adjustment precision, resulting in large deviations in rubber sheet thickness and poor consistency in thickness within the same roll. The cutting stage often uses manual cutting or simple tools, lacking dedicated cutting dies adapted to the skeleton size. The cut rubber sheets have low dimensional accuracy and are prone to burrs, which can easily lead to incomplete coverage or excessive overlap during subsequent application, directly causing inconsistent rubber height on the product surface and easily causing material shortage defects due to insufficient rubber sheet size.

[0004] In the vulcanization and subsequent processing stages, traditional vulcanization molds lack effective skeleton positioning structures. After the rubber sheet and skeleton are bonded, displacement easily occurs during vulcanization, and insufficient mold venting easily leads to air bubbles forming inside the rubber. Improper demolding temperature control often results in deformation of the semi-finished product due to excessive temperature differences. Secondary vulcanization is often carried out in an environment without a protective atmosphere, making the rubber prone to oxidation and aging, affecting product durability. Inspection relies heavily on manual visual inspection, which has low accuracy and efficiency in identifying defects such as rubber height deviation and minor material shortages. A large number of substandard products enter the market, increasing after-sales costs for automakers and potentially causing safety hazards due to seal failure. In summary, existing manufacturing processes are insufficient to meet the current high-quality requirements of the automotive industry for rubber seals, and a more precise and efficient manufacturing method is urgently needed to address these technical pain points. Summary of the Invention

[0005] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides an automotive rubber seal and its preparation method.

[0006] (II) Technical Solution A method for manufacturing automotive rubber seals includes the following steps: S1, Blanking and punching of skeleton: The metal skeleton substrate is blanked and punched using CNC stamping equipment. The stamping deviation is controlled by the cooperation between the pre-positioning pin in the stamping die and the pre-positioning hole on the edge of the substrate to obtain the skeleton blank of the pre-shaped shape. S2, skeleton treatment: First, the skeleton blank is subjected to surface micro-roughening treatment, then placed in zinc phosphating solution for phosphating, and then a rubber-specific primer adhesive is applied to the surface of the phosphating layer and dried with infrared. S3, Rubber compounding: Weigh the EPDM rubber base material, sulfur vulcanizing agent, accelerator, reinforcing agent and antioxidant according to the preset mass ratio, and put them into the internal mixer in stages to control the temperature and speed for mixing to obtain a uniform compound. S4, Rubber sheet production: The mixed rubber is fed into a two-roll mill and pressed into continuous rubber sheets by adjusting the step-by-step roller gap, controlling the thickness of the rubber sheets and the thickness deviation of the same roll of rubber. S5, Film Cutting: Design a special die according to the shape of the skeleton blank, and use a hydraulic cutting machine to cut the continuous film to obtain a shaped film with a size slightly larger than the skeleton blank. S6, vulcanization molding: A vulcanization mold with a skeleton positioning boss is used. After the molding film is attached to the skeleton blank, it is placed into the mold. The air is first degassed and then the pressure is increased for vulcanization to obtain a semi-finished product. S7, Disulfide Treatment: The semi-finished product is placed in a hot air circulating oven and nitrogen gas is introduced for secondary vulcanization. S8, Inspection and Packaging: A laser thickness gauge is used to detect the height of the rubber on the product surface. A visual inspection system is used to screen for material shortages. Qualified products are wrapped with anti-static materials, stacked with cushioning, and then sealed in corrugated cardboard boxes.

[0007] Preferably, in step S1, the stamping frequency of the CNC stamping equipment is controlled at 10-15 times / min, the cutting edge of the stamping die is made of cemented carbide and the sharpness of the cutting edge is kept below Ra0.8μm, and the cutting edge is ground and repaired after every 5000 stampings; the metal skeleton substrate is soaked in an alkaline degreasing agent at 50-60℃ for 10-15 minutes before stamping, then rinsed with deionized water until the pH value is neutral, and then dried with hot air before being put into the stamping process.

[0008] Preferably, in step S2, the surface micro-roughening treatment is carried out by sandblasting with 80-120 mesh white corundum; the concentration of zinc phosphating solution is 15-25%, the phosphating temperature is controlled at 35-45℃, the treatment time is 12-18min, and ultrasonic assistance is used during the phosphating process; after phosphating, the skeleton blank is first washed with deionized water, and then the adhesive is applied.

[0009] Preferably, the rubber-specific primer adhesive in step S2 is a phenolic resin type adhesive; the infrared drying uses a medium-wave infrared heater, and the drying temperature is controlled at 80-100℃. After drying, the dry film thickness is measured by a film thickness gauge to ensure that the dry film thickness is stable at 5-10μm.

[0010] Preferably, the mass ratio of each raw material in step S3 is EPDM rubber substrate: sulfur vulcanizing agent: tetramethylthiuram disulfide accelerator: N330 carbon black reinforcing agent: 2,2,4-trimethyl-1,2-dihydroquinoline polymer antioxidant = 100: (1.5-2.5): (0.8-1.2): (30-40): (1.0-1.5); the rotor speed of the internal mixer is 20-30 r / min in the low-speed mixing stage, 40-50 r / min in the medium-speed mixing stage, and 60-70 r / min in the high-speed mixing stage; after mixing, the mixed rubber is placed on a cooling rack to cool naturally to room temperature, and then placed in a constant temperature and humidity environment of 23±2℃ and 40-60% for aging.

[0011] Preferably, in step S4, the rollers of the two-roll open mill are made of chromium-molybdenum alloy steel, and the roller surface is quenched to a hardness of HRC58-62. The roller temperature is controlled at 60-80℃ and the temperature difference between the front and rear rollers does not exceed ±2℃. The roller gap adjustment accuracy is ±0.05mm. During the film output process, a laser online thickness gauge is used to monitor the film thickness in real time, and the thickness data is recorded every 100mm. When the thickness deviation is detected to exceed ±0.03mm, the equipment automatically adjusts the roller gap. After the continuous film is cooled to 30-40℃ by the cooling roller, it is wound up by the winding machine.

[0012] Preferably, in step S5, the special die is made of Cr12MoV mold steel, and after quenching and low-temperature tempering, the die hardness reaches HRC58-62. The die cutting edge adopts a rounded transition of R0.3-R0.5mm. The cutting pressure of the hydraulic cutting machine is controlled at 2-5MPa, the cutting speed is controlled at 10-20mm / s, and a 0.5-1mm thick polyurethane buffer pad is laid on the surface of the cutting machine worktable. The Shore hardness of the buffer pad is 50-60A. After cutting, the size of the forming film is detected by a two-dimensional image measuring instrument to ensure that the length and width of the forming film are 0.5-2mm larger than the corresponding size of the skeleton blank, and the dimensional deviation does not exceed ±0.05mm. At the same time, the edge of the forming film is checked to ensure that there are no cracks and the burr length does not exceed 0.1mm.

[0013] Preferably, in step S6, the vulcanizing mold is made of P20 pre-hardened plastic mold steel, and the surface of the mold cavity is polished to below Ra0.4μm; the height of the skeleton positioning boss is 0.3-0.5mm, and the surface of the boss is provided with an annular groove; after the bonding component is placed into the mold, the pressure is first vented at 0.5-1MPa for 20-30 seconds. During the venting process, the moving mold slowly descends to a distance of 5-10mm from the fixed mold, and then the mold is quickly closed and the pressure is increased to 5-10MPa. Vulcanization is carried out at 150-180℃ for 10-20 minutes; after vulcanization, the mold is cooled to 80-100℃ before demolding.

[0014] Preferably, in step S7, the hot air circulating oven is heated by an electric heating tube, and multiple temperature sensors are installed inside the oven to ensure temperature uniformity ≤ ±2℃, and the wind speed is controlled at 1-1.5m / s; the purity of the introduced nitrogen gas is ≥99.99%, the nitrogen flow rate is controlled at 1-2L / min, and the nitrogen gas is introduced from the bottom of the oven and discharged from the top to form convection; the secondary vulcanization temperature is 120-150℃, and the time is 5-10min; after the secondary vulcanization, the semi-finished product is placed in the cooling chamber and cooled to room temperature at a rate of 5-8℃ / min. After cooling, the product surface is wiped with 75% medical alcohol to remove residual vulcanization byproducts.

[0015] Preferably, the automotive rubber seal is manufactured using the aforementioned automotive rubber seal preparation method.

[0016] (iii) Beneficial technical effects Compared with existing technologies, the beneficial effects of this invention are: 1. By using CNC stamping equipment in conjunction with positioning pins, the dimensional accuracy of the skeleton blank is improved, effectively avoiding edge burrs and hole misalignment, providing a precise foundation for subsequent rubber bonding; the micro-roughening treatment of the skeleton surface combined with ultrasonic-assisted phosphating significantly enhances the bonding force between the phosphating layer and the skeleton substrate. Furthermore, the automatic spraying and infrared drying control of adhesive thickness greatly improve the bonding strength between the rubber and the skeleton, fundamentally solving the potential problem of delamination during long-term use.

[0017] 2. Precise control of mixing temperature and speed in stages, combined with clear raw material ratios, ensures uniform dispersion of each compounding agent in the compound, effectively improving the stability of the compound's performance and guaranteeing the overall performance consistency of the seals; the step-by-step roller gap adjustment and online thickness monitoring of the two-roll open mill significantly improve the uniformity of the rubber sheet thickness, and with the help of special die cutting, it solves the problem of inconsistent rubber height on the product surface in traditional processes, while effectively avoiding material shortage defects, and greatly improving the product's appearance and dimensional accuracy.

[0018] 3. The positioning boss and annular groove design of the vulcanizing mold effectively prevents the rubber sheet from shifting during the vulcanization process. The pre-venting operation avoids the generation of air bubbles inside the rubber. The reasonable demolding temperature control reduces the deformation of the semi-finished product. The secondary vulcanization under nitrogen protection effectively inhibits the oxidative aging of the rubber and significantly improves the durability and performance stability of the product. Attached Figure Description

[0019] Figure 1 This is a process flow diagram of a method for preparing automotive rubber seals disclosed in this invention; Figure 2 This is a line graph comparing the positive and negative deviations of the skeleton dimensions and the positive and negative deviations of the film thickness in the embodiments and comparative examples; Figure 3 This is a bar chart comparing the bonding strength between the rubber and the skeleton and the product defect rate in the examples and comparative examples; Figure 4 This is a radar comparison chart created by standardizing the dimensions of the performance comparison data of the examples and comparative examples. Detailed Implementation

[0020] according to Figures 1 to 4 The specific embodiments of the present invention are as follows: Example 1 S1: Blanking and punching of the skeleton Q235 cold-rolled steel sheet was selected as the metal skeleton substrate, with a substrate thickness of 1.2mm. Before stamping, the substrate was immersed in a 5% sodium hydroxide-based alkaline degreasing agent at 55℃ for 12 minutes, with stirring every 3 minutes during immersion to ensure uniform degreasing. Then, it was rinsed three times with deionized water with a conductivity ≤10μS / cm, each rinse lasting 1 minute. The pH value of the rinsing solution was checked with precision pH test paper to ensure it was 7.0. Finally, the substrate was placed in a hot air drying oven and dried at 80℃ for 8 minutes to completely remove surface moisture. The blanking and punching process is carried out using a CNC stamping machine with a stamping force of 160kN. The stamping frequency is set to 12 times / min. The cutting edge of the stamping die is made of YG8 cemented carbide, and the cutting edge sharpness is tested to be Ra0.6μm. Three positioning pins with a diameter of 2mm are pre-set in the die, which are precisely matched with the positioning holes pre-machined on the edge of the base material to control the stamping deviation ≤±0.02mm. After every 5000 stamping cycles, the cutting edge is ground and repaired with diamond grinding paste to maintain the stability of stamping quality. Finally, a ring skeleton blank with an outer diameter of 80mm and an inner diameter of 60mm is obtained.

[0021] S2: Skeleton Processing 100-mesh white corundum abrasive conforming to GB6408-86 standard was used to sandblast the surface of the skeleton blank using a pressure sandblasting machine. The sandblasting pressure was set to 0.4 MPa, the sandblasting distance to 150 mm, the sandblasting angle to 45°, and the treatment time to 30 s, so that the surface roughness of the skeleton reached Ra1.2 μm to enhance the adhesion of the subsequent phosphating layer. After the surface micro-roughening treatment was completed, a 20% zinc-based phosphating solution was prepared, and the sandblasted skeleton blank was placed in the phosphating tank. The phosphating temperature was controlled at 40℃, and an ultrasonic generator with a frequency of 28 kHz was turned on to assist phosphating. The treatment time was 15 min. Immediately after phosphating, the skeleton blank was rinsed twice in deionized water, with each rinse lasting 2 min, to remove residual phosphating solution from the surface. After phosphating, a phenolic resin-based rubber primer adhesive was selected and evenly applied to the phosphating layer surface using an automatic sprayer. The spraying pressure was set to 0.3 MPa and the spraying distance to 100 mm. The skeleton was then placed in a 3 kW mid-wave infrared oven and dried at 85°C for 15 minutes. After drying, the dry film thickness of the adhesive was measured using a film thickness gauge with a detection accuracy of ±1 μm to ensure that the thickness was stable at 8 μm. At least 5 detection points were used, and the average value was taken as the final thickness result.

[0022] S3: Rubber compounding Accurately weigh the following raw materials according to the following mass ratio: 100 parts of EPDM 4045 grade ethylene propylene diene monomer (EPDM) rubber, 2.0 parts of industrial-grade sulfur vulcanizing agent with a particle size of 100 mesh, 1.0 part of tetramethylthiuram disulfide accelerator, 35 parts of N330 carbon black reinforcing agent, and 1.2 parts of 2,2,4-trimethyl-1,2-dihydroquinoline polymer antioxidant. Add the raw materials to a 1.5L internal mixer in stages. First, add the EPDM rubber and mix at a low speed of 25 r / min for 3 minutes to fully soften the rubber. Then add the carbon black reinforcing agent and antioxidant, and mix at a medium speed of 45 r / min for 5 minutes, controlling the temperature of the mixing chamber to ≤80℃. Finally, add the sulfur vulcanizing agent and accelerator, and mix at a high speed of 65 r / min for 2 minutes, controlling the temperature of the mixing chamber to ≤100℃. After mixing, the mixed rubber is removed and placed on a stainless steel cooling rack to cool naturally to room temperature. Then, the mixed rubber is placed in a constant temperature and humidity chamber and aged for 12 hours at a temperature of 23°C and a humidity of 50%.

[0023] S4: Rubber compound sheeting The aged rubber compound is fed into a two-roll open mill with a roller diameter of 160mm and a roller surface length of 400mm. The rollers are made of chromium-molybdenum alloy steel, and the surface is hardened to HRC60. The roller temperature is controlled at 70℃, with a temperature difference of 1℃ between the front and rear rollers. The roller gap is adjusted electrically via a stepper motor, with an initial roller gap set at 3mm and gradually adjusted to the target thickness of 2.0mm. The roller gap adjustment accuracy is ±0.05mm. During the film output process, a laser online thickness gauge with a detection accuracy of ±0.001mm is used to monitor the film thickness in real time. Thickness data is recorded every 100mm. When the detected thickness deviation exceeds ±0.03mm, the equipment automatically adjusts the roller gap to compensate. After the continuous film is cooled to 35℃ by cooling rollers, it is wound up using a winding machine with a maximum winding diameter of 500mm. The length of each roll is set to 50m, and the winding tension is controlled at 50N to avoid stretching and deformation of the film.

[0024] S5: Film Cutting A special ring-shaped die was designed based on the shape of the ring-shaped skeleton blank. The die was made of Cr12MoV mold steel and underwent quenching treatment at 950℃ for 2 hours and low-temperature tempering treatment at 200℃ for 4 hours, achieving a die hardness of HRC60. The die cutting edge adopted a 0.4mm radius rounded transition to prevent the film from cracking during cutting. The wound continuous film was placed on the worktable of a hydraulic cutting machine with a maximum cutting force of 1200kN. The worktable surface was covered with a 0.8mm thick polyurethane buffer pad with a Shore hardness of 55A. The cutting pressure was set to 3MPa and the cutting speed to 15mm / s. The equipment was started to cut the film in a ring shape, resulting in a formed film with an outer diameter of 81mm and an inner diameter of 59mm. After cutting, the dimensions of the formed film are checked with a 2D image measuring instrument with a measurement accuracy of ±0.001mm to ensure that the dimensional deviation is ≤±0.05mm. At the same time, the edge of the film is observed with a magnifying glass with a magnification of 10x to confirm that there are no cracks and the burr length is ≤0.08mm.

[0025] S6: Vulcanization molding The vulcanizing mold is made of P20 pre-hardened plastic mold steel. The mold cavity surface is polished to a roughness of Ra0.3μm. The mold has a skeleton positioning boss with a height of 0.4mm, and the surface of the boss has an annular groove with a width of 0.2mm and a depth of 0.1mm to enhance positioning stability. The molding film is evenly applied to the surface of the skeleton blank, ensuring no air bubbles or wrinkles. Then, the bonding assembly is placed in the vulcanizing mold, and the vulcanizing machine with a maximum clamping force of 400kN is started. First, the air is vented at a pressure of 0.8MPa for 25 seconds. During the venting process, the moving mold slowly descends to a distance of 8mm from the fixed mold to fully expel the air inside the cavity. Then, the mold is quickly closed and the pressure is increased to 8MPa. Vulcanization is carried out at 160℃ for 15 minutes. After vulcanization, the mold is cooled to 90℃ at a rate of 5℃ / min. Then, the demolding operation is performed to obtain the semi-finished automotive rubber seal.

[0026] S7: Disulfide treatment The semi-finished product was placed in a 150L hot air circulating oven. Four PT100 temperature sensors were installed inside the oven to ensure temperature uniformity within ≤±2℃. The airflow speed was set to 1.2m / s. 99.995% pure nitrogen gas was introduced into the oven at a flow rate of 1.5L / min, with the nitrogen entering from the bottom and exiting from the top to create a stable convective atmosphere and prevent rubber oxidation. The secondary vulcanization temperature was set to 135℃, and the holding time was 8 minutes. After secondary vulcanization, the semi-finished product was removed and placed in a cooling chamber, where it was cooled to room temperature at a rate of 6℃ / min. After cooling, the product surface was gently wiped with a lint-free cloth soaked in 75% medical alcohol to remove residual vulcanization byproducts, taking care not to scratch the rubber surface during the wiping process.

[0027] S8: Inspect packaging The surface rubber height of the product is measured using a laser thickness gauge with a measurement range of 0-10mm and an accuracy of ±0.001mm. Eight evenly distributed inspection points ensure that the rubber height deviation is ≤±0.03mm. A visual inspection system with a resolution of 2 million pixels is used to screen for defects such as missing material, bubbles, and cracks, with an inspection accuracy of 0.01mm. Qualified products are first individually wrapped in PE antistatic film with a thickness of 0.05mm and a surface resistivity of 10^8-10^10Ω, then stacked on a tray with EVA cushioning pads, with the stacking height not exceeding 30cm. Finally, they are packed into corrugated cardboard boxes with a burst strength ≥120kPa, filled with pearl cotton cushioning material, sealed, and labeled with product specifications and production date.

[0028] Example 2 S1: Blanking and punching of the skeleton SPCC cold-rolled steel sheet with a thickness of 1.0 mm was selected as the metal skeleton substrate. Before stamping, the substrate was immersed in a 5% sodium carbonate alkaline degreasing agent at 50°C for 15 minutes, with stirring twice during immersion. It was then rinsed with deionized water until the pH of the rinsing solution reached 7.0. The substrate was then placed in a hot air drying oven and dried at 75°C for 10 minutes to remove surface moisture. A CNC stamping machine with a stamping force of 100 kN was used for blanking and punching, with a stamping frequency of 10 times / min. The stamping die cutting edge was made of YG6 cemented carbide, and its sharpness was tested to be Ra0.7 μm. Pre-set locating pins in the die cooperated with pre-set locating holes in the substrate to control the stamping deviation to ≤±0.03 mm. After every 5000 stamping cycles, the cutting edge was ground and repaired, ultimately yielding a ring-shaped skeleton blank with an outer diameter of 70 mm and an inner diameter of 50 mm.

[0029] S2: Skeleton Processing Using 80-mesh white corundum abrasive conforming to GB6408-86 standards, the surface of the skeleton blank was sandblasted using a pressure sandblasting machine. The sandblasting pressure was set to 0.3 MPa, the sandblasting distance to 140 mm, the sandblasting angle to 45°, and the processing time to 25 seconds, achieving a surface roughness of Ra 1.0 μm. Next, a 15% zinc-based phosphating solution was prepared, and the skeleton blank was placed in the phosphating tank. The phosphating temperature was controlled at 35°C, and an ultrasonic generator was used to assist phosphating for 18 minutes. After phosphating, the blank was rinsed twice with deionized water to remove residual phosphating solution. After rinsing, a phenolic resin-based rubber primer was applied using an automatic sprayer. The spraying pressure was set to 0.3 MPa, and the spraying distance to 100 mm. The blank was then placed in a mid-wave infrared oven and dried at 80°C for 20 minutes. The dry film thickness of the adhesive was measured using a film thickness gauge to ensure a stable thickness of 5 μm.

[0030] S3: Rubber compounding Weigh the raw materials according to the following mass ratio: 100 parts of EPDM 3092 grade ethylene propylene diene monomer (EPDM) rubber, 1.5 parts of industrial-grade sulfur vulcanizing agent, 0.8 parts of tetramethylthiuram disulfide accelerator, 30 parts of N330 carbon black reinforcing agent, and 1.0 part of 2,2,4-trimethyl-1,2-dihydroquinoline polymer antioxidant. Add the raw materials to a 1.5L internal mixer in stages. First, add the EPDM rubber and mix at a low speed of 20 rpm for 3 minutes. Then add the carbon black reinforcing agent and antioxidant, and mix at a medium speed of 40 rpm for 6 minutes, controlling the temperature of the mixing chamber to ≤95℃. Finally, add the sulfur vulcanizing agent and accelerator, and mix at a high speed of 60 rpm for 2 minutes. After mixing, allow the compound to cool naturally to room temperature and place it in a constant temperature and humidity chamber for aging at 21℃ and 40% humidity for 10 hours.

[0031] S4: Rubber compound sheeting The aged rubber compound is fed into a two-roll open mill with a roller diameter of 140mm and a roller surface length of 320mm. The rollers are made of chromium-molybdenum alloy steel and have a surface hardness of HRC58 after quenching. The roller temperature is controlled at 60℃ with a temperature difference of 2℃ between the front and rear rollers. The roller gap is adjusted in a stepwise manner to achieve the target thickness of 1.8mm with an adjustment accuracy of ±0.05mm. During the film output process, the thickness is monitored in real time using a laser online thickness gauge, and data is recorded every 100mm. When the deviation exceeds ±0.03mm, the roller gap is automatically adjusted. After the continuous film is cooled to 30℃ by cooling rollers, it is wound up by a winding machine with a length of 40m and a winding tension of 50N.

[0032] S5: Film Cutting A special ring-shaped die was designed based on the shape of the skeleton blank. The die was made of Cr12MoV mold steel, and after quenching and low-temperature tempering, the hardness reached HRC58. The cutting edge used a 0.3mm radius rounded transition. The continuous film was placed on the worktable of the hydraulic cutting machine. The worktable was covered with a 0.5mm thick polyurethane buffer pad with a Shore hardness of 50A. The cutting pressure was set to 2MPa and the cutting speed to 10mm / s. The machine was started to cut, resulting in a shaped film with an outer diameter of 70.5mm and an inner diameter of 49.5mm. After cutting, the dimensions were checked with a 2D image measuring instrument to ensure that the deviation was ≤±0.05mm. The edges were observed with a magnifying glass to confirm that there were no cracks and the burr length was ≤0.09mm.

[0033] S6: Vulcanization molding The vulcanizing mold is made of P20 pre-hardened plastic mold steel, with the cavity surface polished to Ra0.4μm. The mold has a 0.3mm high skeleton positioning boss inside. The bonding component is placed in the mold, and the pressure is first vented at 0.5MPa for 30 seconds. Then, the mold is quickly closed and the pressure is increased to 5MPa. Vulcanization is carried out at 150℃ for 20 minutes. After vulcanization, the mold temperature is controlled to be reduced to 80℃ before demolding to obtain the semi-finished product.

[0034] S7: Disulfide treatment The semi-finished product was placed in a hot air circulating oven with a wind speed of 1.0 m / s and 99.99% pure nitrogen gas introduced at a flow rate of 1 L / min. The secondary vulcanization temperature was set to 120℃, and the holding time was 10 min. After the secondary vulcanization, the semi-finished product was placed in a cooling chamber and cooled to room temperature at a rate of 5℃ / min. After cooling, the surface was wiped with 75% medical alcohol.

[0035] S8: Inspect packaging The thickness of the rubber on the product surface is measured with a laser thickness gauge, and defects are screened with a visual inspection system. Qualified products are wrapped in PE antistatic film, stacked in a tray with EVA cushioning pads, and then packed into a corrugated cardboard box and sealed. The box is filled with cushioning material and labeled.

[0036] Example 3 S1: Blanking and punching of the skeleton DC01 cold-rolled steel sheet with a thickness of 1.5mm was selected as the base material for the metal skeleton. Before stamping, the base material was immersed in a 6% sodium hydroxide alkaline degreasing agent at 60℃ for 10 minutes, then rinsed with deionized water until the pH value reached 7.0, and placed in a hot air drying oven at 85℃ for 6 minutes to remove surface moisture. A CNC stamping machine with a stamping force of 250kN was used for blanking and punching, with a stamping frequency of 15 times / min. The cutting edge of the stamping die was made of YG10 cemented carbide, with a sharpness of Ra0.5μm. The die positioning pin was matched with the pre-positioning hole of the base material to control the stamping deviation ≤±0.01mm. The cutting edge was ground after every 5000 stamping cycles, and finally a ring skeleton blank with an outer diameter of 90mm and an inner diameter of 70mm was obtained.

[0037] S2: Skeleton Processing Using 120-mesh white corundum abrasive conforming to GB6408-86 standards, the skeleton was sandblasted using a pressure sandblasting machine at a pressure of 0.5 MPa, a distance of 160 mm, and a time of 35 seconds, achieving a surface roughness of Ra 1.5 μm. Next, a 25% zinc-based phosphating solution was prepared, and the skeleton blank was placed in the phosphating bath. The temperature was controlled at 45℃, and ultrasonic-assisted phosphating was performed for 12 minutes. After phosphating, the skeleton was rinsed twice to remove residual solution. After rinsing, a phenolic resin-based rubber primer was applied at a spray pressure of 0.3 MPa and a distance of 100 mm. The skeleton was then placed in a mid-wave infrared oven and dried at 100℃ for 12 minutes. The dry film thickness was measured using a film thickness gauge to ensure it remained stable at 10 μm.

[0038] S3: Rubber compounding Weigh the raw materials according to the following mass ratio: 100 parts of EPDM 5050 grade ethylene propylene diene monomer (EPDM) rubber, 2.5 parts of industrial-grade sulfur vulcanizing agent, 1.2 parts of tetramethylthiuram disulfide accelerator, 40 parts of N330 carbon black reinforcing agent, and 1.5 parts of 2,2,4-trimethyl-1,2-dihydroquinoline polymer antioxidant. Add the raw materials to a mixing mill in stages: first, mix at a low speed of 30 rpm for 2 minutes; then, mix at a medium speed of 50 rpm for 4 minutes, controlling the temperature of the mixing chamber to ≤105℃; finally, mix at a high speed of 70 rpm for 2 minutes. After cooling, age the compound in a constant temperature and humidity environment of 25℃ and 60% for 14 hours.

[0039] S4: Rubber compound sheeting The compounded rubber was fed into a two-roll open mill with a roller diameter of 180mm and a roller surface length of 450mm. After quenching, the rollers were hardened to HRC62 at 80℃, with a temperature difference of 0℃ between the front and rear rollers. The roller gap was adjusted to 2.2mm with an accuracy of ±0.05mm. A laser thickness gauge was used for real-time monitoring, and automatic adjustment was made if the deviation exceeded ±0.03mm. After the rubber sheet cooled to 40℃, it was wound up to 60m per roll with a tension of 50N.

[0040] S5: Film Cutting The specialized die-cutting mold is made of Cr12MoV steel, with a hardness of HRC62 after quenching and tempering, and a cutting edge radius of 0.5mm. The hydraulic cutting machine operates at a pressure of 5MPa and a speed of 20mm / s, with a 1mm thick polyurethane cushioning pad of Shore 60A on the worktable. The cut yields a shaped film with an outer diameter of 92mm and an inner diameter of 68mm, with a dimensional deviation ≤±0.05mm and burrs ≤0.07mm.

[0041] S6: Vulcanization molding The vulcanizing mold cavity is polished to Ra0.3μm, the positioning boss height is 0.5mm, the air is first vented at 1MPa pressure for 20 seconds, the mold is closed and the pressure is increased to 10MPa, vulcanized at 180℃ for 10min, and then cooled to 100℃ to demold, obtaining a semi-finished product.

[0042] S7: Disulfide treatment The hot air circulating oven has a wind speed of 1.5 m / s, a nitrogen purity of 99.996%, a flow rate of 2 L / min, a secondary vulcanization at 150℃ for 5 min, a cooling rate of 8℃ / min, and the surface is wiped with alcohol after cooling.

[0043] S8: Inspect packaging After passing laser thickness measurement and visual inspection, the product is wrapped in anti-static material, stacked with cushioning, and then placed in a corrugated cardboard box and sealed with labels.

[0044] Comparative Example S1: Blanking and punching of the skeleton A standard mechanical punch press with a stamping force of 160kN is used. It lacks a locating pin structure and relies solely on die guidance. The stamping frequency is 8 times / min. The die cutting edge is made of Cr12 steel, with a sharpness of Ra1.2μm, and is not periodically ground or repaired. The metal skeleton substrate is only rinsed with water without degreasing. The resulting skeleton blank has a dimensional deviation of ±0.1mm and an edge burr length of 0.3-0.5mm.

[0045] S2: Skeleton Processing Without surface roughening treatment, the skeleton blank is directly placed in a 10% zinc phosphate solution and phosphated at 50°C for 20 minutes without ultrasonic assistance. After phosphated, a general-purpose rubber adhesive is manually applied, resulting in uneven coating thickness. The material is then allowed to air dry naturally without infrared drying or testing of the adhesive dry film thickness.

[0046] S3: Rubber compounding The raw material ratio is determined by experience and weighing. The approximate ratio is 100 parts EPDM rubber, 2 parts sulfur, 1 part accelerator, 35 parts carbon black, and 1 part antioxidant. There is no precise quality control. A regular 1.0L internal mixer is used, and the mixture is mixed at a single speed of 40r / min for 10 minutes. The temperature of the mixing chamber is not controlled. After mixing, the rubber is not aged and is directly put into the next process.

[0047] S4: Rubber compound sheeting A standard open mill with a roller diameter of 160mm is used. The roller temperature is not controlled. The roller gap is adjusted manually with an adjustment accuracy of ±0.2mm. There is no online thickness measurement device. The film thickness deviation is ±0.1mm, and the thickness consistency of the same roll of film is poor.

[0048] S5: Film Cutting Without a dedicated die, the film is cut by hand using scissors according to the approximate size of the skeleton. After cutting, the size deviation of the film is ±0.3mm, the length of the rough edge is 0.2-0.4mm, and some films have problems such as cracking and irregular shape.

[0049] S6: Vulcanization molding Using a common vulcanizing mold without a skeleton positioning structure, the rubber sheet is directly molded after being bonded to the skeleton without a pre-venting step. The vulcanizing pressure is set to 6MPa, and vulcanization is carried out at 160℃ for 15 minutes. The mold is demolded immediately after vulcanization, which makes the semi-finished product easy to deform and contains air bubbles inside the rubber.

[0050] S7: Disulfide treatment There is no secondary vulcanization process. After vulcanization, the semi-finished product is directly cooled to room temperature naturally without surface cleaning treatment, and residual vulcanization by-products adhere to the product surface.

[0051] S8: Inspect packaging The product appearance is inspected manually by visual inspection, without laser thickness gauges or vision inspection systems. Qualified products are directly packed into ordinary cardboard boxes without anti-static wrapping or cushioning materials inside the boxes.

[0052] The performance comparison between the examples and the comparative examples is shown in the table below: Table 1 Testing items Example 1 Example 2 Example 3 Comparative Example Positive and negative deviation of skeleton dimensions (mm) 0.02 0.03 0.01 0.1 Bond strength between rubber and skeleton (MPa) 3.8 3.5 4.2 1.5 Film thickness positive and negative deviation (mm) 0.03 0.03 0.02 0.1 Product defect rate (%) 0.5 0.8 0.3 15.2 Rubber tensile strength (MPa) 12.5 11.8 13.2 8.6 Elongation at break of rubber (%) 450 430 480 320 Tensile strength retention rate after heat aging (120℃×72h) 92% 90% 95% 65% Fatigue resistance (times) ≥10^6 ≥10^6 ≥10^6 3×10^5 Compared with the comparative example, this invention solves the core pain points of traditional automotive rubber seals, namely "large dimensional deviation, weak adhesion, unstable performance, and high defect rate," through systematic innovation of "precision process throughout the entire process + structural optimization of key links," and achieves a comprehensive upgrade in product precision, reliability, and durability.

[0053] The embodiment utilizes CNC stamping positioning pin control, micro-roughening of the skeleton surface + ultrasonic assisted phosphating, and precise application of adhesive and infrared drying. The skeleton size deviation is only 0.01-0.03mm, and the bonding strength between rubber and skeleton reaches 3.5-4.2MPa, far exceeding the comparative example. This solves the problems of hole position misalignment and delamination in traditional processes.

[0054] The example demonstrates that through staged temperature-controlled mixing, online thickness measurement and automatic compensation on a two-roll mill, and cutting with a special die, the film thickness deviation is only 0.02-0.03mm, and the product defect rate is as low as 0.3-0.8%. In contrast, the comparative example, due to manual cutting and lack of precision control, has a film thickness deviation of 0.1mm and a defect rate of 15.2%.

[0055] The rubber in the example has a tensile strength of 11.8-13.2 MPa, an elongation at break of 430-480%, a tensile strength retention rate of 90-95% after heat aging, and a fatigue resistance of ≥10 cycles. 6 The ratio is significantly higher than that of the control group; this is due to the optimization of the vulcanizing mold positioning boss + pre-venting design, nitrogen protection secondary vulcanization, etc., which effectively avoids displacement, bubbles and oxidation aging.

[0056] The comparative example, due to a lack of precise positioning, rough surface treatment, disordered rubber processing, and lack of protection and venting during vulcanization, resulted in large dimensional deviations, easy delamination of the bond, and rapid performance degradation, completely failing to meet the high-quality requirements of the automotive industry. In contrast, the embodiment, through precise control of the entire process and optimization of key structures, achieved the comprehensive advantages of "precise dimensions, strong adhesion, stable performance, and long service life," fully demonstrating the beneficial effects of the present invention and providing a reliable solution for the high-quality industrialization of automotive rubber seals.

[0057] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method of manufacturing a rubber seal for a vehicle, characterized by, The method comprises the following steps: S1, skeleton blanking and punching: using a numerical control stamping equipment to perform blanking and punching processing on a metal skeleton base material, controlling the stamping deviation through the cooperation of the pre-set positioning pins in the stamping die and the pre-positioning holes on the edge of the base material, and obtaining a skeleton blank with a pre-set shape; S2, skeleton processing: first performing surface micro-roughening treatment on the skeleton blank, then placing it in a zinc-based phosphating solution for phosphating, and then brushing a rubber special primer adhesive on the surface of the phosphating layer and using infrared drying; S3, rubber mixing: weighing the ethylene-propylene-diene rubber base material, sulfur vulcanizing agent, accelerator, reinforcing agent, and antioxidant according to the preset mass ratio, and feeding them into a mixer in stages to control the temperature and speed of mixing, and obtaining uniformly mixed rubber; S4, rubber sheeting: feeding the mixed rubber into a two-roll open mill, and pressing it into a continuous rubber sheet through step-by-step roll gap adjustment, and controlling the rubber sheet thickness and the thickness deviation of the same volume rubber sheet; S5, rubber sheet cutting: designing a special cutter according to the shape of the skeleton blank, and cutting the continuous rubber sheet using a hydraulic cutting machine to obtain a formed rubber sheet slightly larger than the skeleton blank; S6, vulcanization forming: using a vulcanization mold with a skeleton positioning boss, placing the formed rubber sheet on the skeleton blank into the mold, first exhausting, then pressurizing and vulcanizing to obtain a semi-finished product; S7, two sulfur treatment: placing the semi-finished product into a hot air circulation oven and performing secondary vulcanization under nitrogen protection; S8, inspection and packaging: using a laser thickness gauge to detect the rubber height on the surface of the product, using a visual inspection system to screen for material defects, and packing the qualified products into corrugated paper boxes after anti-static wrapping and cushion stacking.

2. The method of claim 1, wherein The stamping frequency of the numerical control stamping equipment in step S1 is controlled to be 10-15 times / min, the cutting edge of the stamping die is made of hard alloy material and the cutting edge sharpness is maintained below Ra0.8μm, and the cutting edge is ground and repaired every 5000 times of stamping; the metal skeleton base material is soaked in an alkaline degreasing agent at 50-60℃ for 10-15min before stamping, then washed with deionized water until the pH value is neutral, and then dried with hot air before being fed into the stamping process.

3. The method of claim 1, wherein In step S2, the surface micro-roughening treatment uses 80-120 mesh white corundum sandblasting; the concentration of the zinc-based phosphating solution is 15-25%, the phosphating treatment temperature is controlled at 35-45℃, the treatment time is 12-18min, and ultrasonic waves are used to assist the phosphating process; after phosphating, the skeleton blank is first washed in deionized water, and then the adhesive is brushed.

4. The method of claim 1, wherein In step S2, the rubber special primer adhesive is a phenolic resin type adhesive; the infrared drying uses a medium wave infrared heater, the drying temperature is controlled at 80-100℃, and after drying, the adhesive dry film thickness is detected using a film thickness gauge to ensure that the dry film thickness is stable at 5-10μm.

5. The method of claim 1, wherein The mass ratio of the raw materials in step S3 is: ternary ethylene-propylene rubber base material: sulfur vulcanizing agent: tetramethyl thiuram disulfide accelerator: N330 carbon black reinforcing agent: 2,2,4-trimethyl-1,2-dihydroquinoline polymer antioxidant = 100: (1.5-2.5): (0.8-1.2): (30-40): (1.0-1.5); the rotor speed of the internal mixer is 20-30 r / min in the low-speed mixing stage, 40-50 r / min in the medium-speed mixing stage, and 60-70 r / min in the high-speed mixing stage; after the mixing is completed, the mixed rubber is placed on a cooling rack to cool naturally to room temperature, and then placed in a constant temperature and humidity environment with a temperature of 23±2℃ and a humidity of 40-60% for aging.

6. The method of claim 1, wherein, In step S4, the roll of the two-roll open mill is made of chromium-molybdenum alloy steel, and the roll surface is quenched to a hardness of HRC58-62, the roll temperature is controlled at 60-80℃, and the temperature difference between the front and rear rolls is not more than ±2℃; the roll gap adjustment accuracy is ±0.05mm; during the sheeting process, a laser online thickness gauge is used to monitor the thickness of the rubber sheet in real time, and the thickness data is recorded every 100mm, when the detected thickness deviation exceeds ±0.03mm, the equipment automatically adjusts the roll gap; the continuous rubber sheet is cooled to 30-40℃ by a cooling roll, and then wound by a winding machine.

7. The method of claim 1, wherein the rubber seal is a vehicle rubber seal. In step S5, the special cutter is made of Cr12MoV die steel, quenched and low-temperature tempered, the cutter hardness reaches HRC58-62, the cutter edge adopts R0.3-R0.5mm arc transition; the cutting pressure of the hydraulic cutting machine is controlled at 2-5MPa, the cutting speed is controlled at 10-20mm / s, and a 0.5-1mm thick polyurethane buffer pad is laid on the surface of the cutting machine workbench, the Shore hardness of the buffer pad is 50-60A; after cutting, the size of the formed rubber sheet is detected by a two-dimensional image measuring instrument to ensure that the length and width of the formed rubber sheet are 0.5-2mm larger than the corresponding size of the skeleton blank, and the size deviation is not more than ±0.05mm, and the edge of the formed rubber sheet is also checked to ensure that there is no cracking and the length of the burr is not more than 0.1mm.

8. The method of claim 1, wherein, In step S6, the vulcanization mold is made of P20 pre-hardened plastic mold steel, and the mold cavity surface is polished to Ra0.4μm or less; the height of the skeleton positioning boss is 0.3-0.5mm, and the boss surface is provided with an annular groove; after the assembly is placed in the mold, it is first evacuated at a pressure of 0.5-1MPa for 20-30 seconds, during the evacuation process, the movable mold of the mold slowly descends to a distance of 5-10mm from the fixed mold, then the mold is quickly closed and the pressure is increased to 5-10MPa, and vulcanized at 150-180℃ for 10-20min; After vulcanization, the mold is cooled to 80-100℃ before demolding.

9. The method of claim 1, wherein, The hot air circulation oven in step S7 is heated by an electric heating tube, multiple groups of temperature sensors are arranged in the oven to ensure that the temperature uniformity is ≤±2℃, the wind speed is controlled at 1-1.5m / s; the purity of the nitrogen gas is ≥99.99%, the nitrogen gas flow is controlled at 1-2L / min, the nitrogen gas is introduced from the bottom of the oven and discharged from the top to form a convection; the secondary vulcanization temperature is 120-150℃, and the time is 5-10min; after the secondary vulcanization, the semi-finished product is placed in a cooling room and cooled to room temperature at a rate of 5-8℃ / min, and after cooling, the surface of the product is wiped with medical alcohol with a concentration of 75% to remove residual vulcanization by-products.

10. An automobile rubber sealing element prepared according to the method of claim 1.

Images