A production process of a new oil seal

Abstract

This invention relates to the field of sealing component manufacturing technology, specifically a novel oil seal production process, comprising the following steps: S1: Preparing metal parts by stamping, including a bushing body, an outer skeleton, an inner skeleton, and a retaining ring; deburring and cleaning the prepared metal parts, followed by phosphating surface treatment; S2: Preparing a lip piece from a PTFE-based mixed powder through pressing and sintering; S3: Extruding AEM rubber after open milling to obtain a first rubber layer and a second rubber layer; S4: Positioning the outer skeleton, inner skeleton, main lip, and secondary lip in a vulcanization mold, adding the second rubber layer, and performing hot-press vulcanization; after demolding, surface treatment, and a second vulcanization to obtain a semi-finished oil seal body; using the same vulcanization process as the semi-finished oil seal body, connecting the first rubber layer to the surface of the bushing body to obtain a rubber-coated bushing; S5: Assembling the rubber-coated bushing, the semi-finished oil seal body, and the retaining ring. The novel oil seal produced by this invention has excellent dynamic and static sealing performance.

Description

Technical Field

[0001] This invention relates to the field of sealing component manufacturing technology, and in particular to a novel oil seal production process. Background Technology

[0002] Oil seals are the core basic components of rotary shaft sealing systems and are widely used in automotive transmissions, construction machinery, hydraulic equipment and other fields. Their core functions are to prevent lubricating oil leakage and to block the intrusion of external dust and mud.

[0003] As industrial equipment develops towards high speed, high temperature, and long service life, combined PTFE oil seals with rubber-coated bushings are increasingly widely used due to their combination of static sealing reliability and dynamic sealing wear resistance.

[0004] Traditional rubber rotary oil seals have a simple structure (only an outer iron shell and a rubber sealing lip with a spring coil). Their sealing surface is narrow and linear, and the clamping force is provided by the spring. Although they are easier to develop and produce, their rubber lip is constantly affected by the spring coil. Although this improves the static sealing ability to a certain extent, it is extremely prone to wear and aging.

[0005] In view of this, the present invention provides a novel oil seal manufacturing process to meet market demand. Summary of the Invention

[0006] To achieve the above objectives, the present invention provides the following technical solution: a manufacturing process for a novel oil seal, the novel oil seal comprising a bushing body, a first adhesive layer vulcanized on the surface of the bushing body, an outer skeleton and an inner skeleton axially sleeved on the outer periphery of the bushing body, a main lip and a secondary lip clamped and vulcanized and bonded between the outer skeleton and the inner skeleton and stacked thereon, a second adhesive layer vulcanized and connected to the outer periphery of the outer skeleton, and a retaining ring fixedly sleeved on the end of the bushing body, characterized in that the manufacturing process of the novel oil seal includes the following steps:

[0007] S1: Metal parts are manufactured by stamping, including bushing body, outer skeleton, inner skeleton and retaining ring; the manufactured metal parts are deburred, cleaned and then subjected to phosphating surface treatment.

[0008] S2: The main lip and the secondary lip are made by pressing and sintering the PTFE-based mixed powder. After the main lip is machined with an angled annular thread, the main lip and the secondary lip are sliced.

[0009] S3: AEM rubber is extruded after open milling to obtain the first rubber layer and the second rubber layer;

[0010] S4: Position the outer skeleton, inner skeleton, main lip and secondary lip into the vulcanization mold, add the second rubber layer and perform hot pressing vulcanization. After demolding, perform surface treatment and then perform secondary vulcanization to obtain the oil seal body semi-finished product. Using the same vulcanization process as the oil seal body semi-finished product, connect the first rubber layer to the surface of the bushing body to obtain the rubber-coated bushing.

[0011] S5: Assemble the rubber-coated bushing, the semi-finished oil seal body, and the retaining ring to obtain the finished oil seal.

[0012] Preferably, in step S1, the bushing body needs to undergo nitriding treatment before phosphating surface treatment.

[0013] Preferably, in S1, the phosphating surface treatment includes degreasing, water washing, rust removal, secondary water washing, surface conditioning, phosphating, cold water washing, tertiary water washing, drying, and rust prevention performed sequentially.

[0014] Preferably, in the degreasing process, the degreasing solution is prepared in the following mass ratio:

[0015] Degreasing solution: tap water = 1:4, degreasing solution pH value: 13~14, degreasing solution temperature: 60℃-70℃, degreasing time: 450s~600s;

[0016] In the rust removal process, the rust removal solution is prepared in the following proportions by mass:

[0017] Hydrochloric acid: tap water = 2:1; rust remover pH value: 1~2; rust remover temperature: room temperature; rust removal time: 450s~600s.

[0018] In the aforementioned table conditioning solution, the mass ratio of the table conditioning solution is as follows:

[0019] Surface conditioning solution: tap water = 1:100, pH value of surface conditioning solution: 8~9, surface conditioning temperature: room temperature, surface conditioning time: 30~60s;

[0020] In the phosphating process, the phosphating agent is formulated in the following proportions by mass:

[0021] Phosphating agent: tap water = 7:100, phosphating agent pH value: 2~2.5, phosphating temperature: 85℃~90℃, phosphating time: 450s~600s, phosphating acid ratio: 6~7.

[0022] Preferably, in step S3, the open mixing is performed using a rubber mixing mill, with a 0.5mm gap for at least 3 thin passes, producing sheets with a thickness of 3-6mm and a width of 50-70mm.

[0023] The extrusion bar is made using an extrusion machine with an extrusion pressure of 40 MPa, an extrusion speed of 10-20 m / min, a take-up speed of 8-15 m / min, an inlet barrel temperature of 58℃-62℃, an intermediate barrel temperature of 63℃-67℃, and an outlet barrel temperature of 68℃-72℃.

[0024] Preferably, in step S4, the surface treatment includes edge tearing, adhesive scraping, edge trimming, and air spray cleaning.

[0025] Preferably, in step S5, before assembly, a warm air blower or a vertical pre-forming machine can be used to bend the free ends of the main lip and the secondary lip to the oil side for pre-forming.

[0026] Preferably, the nitriding treatment is performed in a nitriding furnace;

[0027] The nitriding conditions included: furnace pressure of 0.5 MPa to 0.6 MPa and ammonia flow rate of 0.4 nm. 3 / h~0.6nm 3 / h, keep warm at 540℃ for 3h~4h.

[0028] Preferably, in step S4, the secondary vulcanization is performed using a programmable oven;

[0029] The secondary vulcanization conditions include: maintaining the temperature inside the chamber at 157℃~163℃ for at least 20 minutes, and maintaining the temperature at 172℃~178℃ for at least 270 minutes.

[0030] Preferably, in step S4, the clamped ends of the main lip and the secondary lip when they are positioned into the vulcanizing mold are coated with sealant at the gap between them and the outer and inner skeletons.

[0031] The beneficial effects of this invention are:

[0032] The novel oil seal obtained by this invention has good dynamic and static sealing performance. Under static conditions, the rubber column strengthens the structural strength of the inner sealing protrusion, resists oil pressure deformation, and maintains stable static sealing performance. Under dynamic conditions, the retaining ring buffers the oil impact and uses oil pressure to enhance the lip contact force. Combined with the double-layer lip structure, it improves sealing reliability while reducing wear and effectively extends the overall service life of the oil seal. Attached Figure Description

[0033] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0034] Figure 1 This is a schematic diagram of the main structure of the oil seal of the present invention;

[0035] Figure 2 This is a schematic diagram of the AA cross-sectional structure of the present invention;

[0036] Figure 3 This is a schematic cross-sectional view of the main lip plate surface with an angled annular thread of the present invention.

[0037] Figure 4 This is a schematic diagram of the main lip plate surface with an angled annular thread of the present invention.

[0038] Figure 5 This is a schematic diagram of the nitriding process of the present invention;

[0039] Figure 6 This is a schematic diagram of the secondary vulcanization process of the present invention.

[0040] In the attached drawings: 1. Bushing body; 11. First adhesive layer; 12. Dustproof lip; 13. Limiting lip; 2. Outer skeleton; 3. Inner skeleton; 4. Main lip piece; 5. Secondary lip piece; 6. Retaining ring; 21. Second adhesive layer. Detailed Implementation

[0041] 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.

[0042] A new type of oil sealing process, such as Figures 1-6 As shown, the novel oil seal structure produced by this process is a coaxial rotary sealing structure, which consists of four parts: a rubber-coated bushing, a skeleton assembly, a sealing lip assembly, and a retaining ring 6. The skeleton assembly is coaxially sleeved on the outer periphery of the rubber-coated bushing, the sealing lip assembly is fixed inside the skeleton assembly and its inner edge forms a sliding seal with the outer periphery of the rubber-coated bushing, and the retaining ring 6 is fixedly installed on the end of the rubber-coated bushing near the oil side.

[0043] The rubber-coated bushing includes a rigid bushing body 1 and a first rubber layer 11 integrally vulcanized on the surface of the bushing body 1. The bushing body 1 is a cylindrical component made of metal, providing rigid support for the entire rubber-coated bushing. The first rubber layer 11 is made of oil-resistant rubber, such as AEM rubber, and completely covers the inner circumferential surface, air-side end face, and part of the outer circumferential surface of the bushing body 1. The bushing body 1 is press-fitted with the rotating shaft of the sealed equipment through the first rubber layer 11 to achieve a static seal between the rubber-coated bushing and the rotating shaft.

[0044] Furthermore, the first rubber layer 11, located on the inner circumferential surface of the bushing body 1, is formed with at least two axially spaced annular protrusions. These annular protrusions extend continuously around the entire circumference, forming multiple static sealing lines by interfering with the surface of the rotating shaft. Between adjacent annular protrusions, several axially extending rubber pillars 111 are evenly spaced circumferentially. The rubber pillars 111 and the annular protrusions are integrally vulcanized, with both ends connected to the annular protrusions on either side. Their radial thickness matches the protrusion height of the annular protrusions. When static oil pressure exists on the oil side, the oil pressure acting on the rubber-coated bushing will cause the annular protrusions to tend to expand radially. The rubber pillars 111 can provide axial tension and radial support to adjacent annular protrusions, limiting excessive deformation and maintaining the stability of the interference fit, thereby ensuring sealing reliability under long-term static conditions.

[0045] At the end of the first adhesive layer 11 near the air side, a dustproof lip 12 is integrally formed. The dustproof lip 12 extends radially outward from the air side end face of the bushing body 1, with its outer edge folded towards the skeleton assembly. Its end face is tightly fitted with the end face of the skeleton assembly near the air side, forming a rotary seal barrier to prevent external dust, mud, water, and other impurities from entering the oil seal from the air side. At the same time, a limiting lip 13 is also formed on the inner side of the dustproof lip 12. The limiting lip 13 extends radially and together with the dustproof lip 12, forms a covering cavity with an opening facing the outer periphery of the bushing body 1. The air side end of the bushing body 1 is fitted into this covering cavity. The covering force of the rubber strengthens the bonding strength between the first adhesive layer 11 and the end of the bushing body 1, preventing the adhesive layer from delaminating during long-term operation.

[0046] The skeleton assembly includes an outer skeleton 2 and an inner skeleton 3, both of which are annular components formed by metal stamping and are coaxially nested together. The outer skeleton 2 is a rotating body with an L-shaped cross-section, including an axially extending cylindrical section and a flange section extending radially inward from the oil-side end of the cylindrical section. The inner skeleton 3 also has an L-shaped cross-section structure and is nested and fixed inside the outer skeleton 2. The two together form a mounting cavity for clamping and fixing the lip assembly. The outer circumferential surface of the cylindrical section of the outer skeleton 2 is also integrally vulcanized with a second adhesive layer 21. The second adhesive layer 21 is made of oil-resistant rubber and is used to make an interference fit with the housing mounting hole of the sealed equipment to achieve a soft connection and static seal between the oil seal and the housing. At the same time, it can absorb the vibration generated by assembly tolerances and equipment operation, and improve assembly stability.

[0047] The lip assembly includes a main lip 4 and a secondary lip 5, both of which are annular lip structures made of PTFE. They are stacked axially, with their roots clamped and vulcanized and bonded between the outer skeleton 2 and the inner skeleton 3, forming a sealed whole with the skeleton assembly. The main lip 4 is positioned closer to the oil side, with its free end bent towards the oil side. Its lip line is tightly fitted to the outer circumferential surface of the bushing body 1, forming the main dynamic seal barrier to prevent lubricating oil from leaking from the oil side to the air side. The secondary lip 5 is stacked on the air side of the main lip 4, with an axial length shorter than the main lip 4. Its free end extends to the bent root of the main lip 4, and its lip line is also fitted to the outer circumferential surface of the bushing body 1, forming an auxiliary seal barrier. When the main lip 4 experiences minor leakage due to long-term wear, the secondary lip 5 can form a second sealing barrier. The double sealing structure significantly improves the sealing reliability. At the same time, the annular cavity formed between the main lip 4 and the secondary lip 5 can store a small amount of lubricating oil, providing continuous lubrication to the lip contact surface, reducing the coefficient of friction, reducing lip wear, and extending the service life of the oil seal.

[0048] The retaining ring 6 is fixedly fitted onto the end of the bushing body 1 near the oil side. It is a rigid annular component with an L-shaped cross-section, partially enclosing the outer side of the free end of the main lip 4. The radial outer edge of the retaining ring 6 extends towards the air side, defining a meandering oil passage together with the flange end face of the outer frame 2 near the oil side. When the oil on the oil side is agitated by the rotating shaft, generating fluid impact, the retaining ring 6 first forms a physical barrier against the direct impact of the oil, preventing high-pressure oil from directly impacting the free end of the main lip 4, causing lip lifting and seal instability. At the same time, after the oil enters the oil passage through the guide of the retaining ring 6, the oil pressure acts on the outer peripheral surface of the main lip 4, forming a radially inward pressing force, making the lip of the main lip 4 fit more tightly against the surface of the bushing body 1, achieving a self-tightening sealing effect of oil pressure—the higher the oil side pressure, the stronger the lip's contact force and the more stable the sealing performance.

[0049] The production process of the present invention will be further described in detail below through three specific embodiments, in conjunction with the above-described oil seal structure.

[0050] Example 1

[0051] This embodiment demonstrates the optimal process parameters for preparing a novel oil seal with dimensions of 88.5mm × 123mm × 14mm. The specific production steps are as follows:

[0052] S1: Metal parts preparation and pretreatment: ST12 high-quality cold-rolled steel sheet was used to prepare the bushing body 1, outer skeleton 2, inner skeleton 3 and retaining ring 6 by precision stamping press. After stamping, all metal parts were deburred and ultrasonically cleaned to remove surface oil and metal debris. The bushing body 1 was first subjected to nitriding surface strengthening treatment: the bushing body 1 was neatly stacked on the nitriding furnace rack, and after vacuuming, ammonia gas was introduced. The furnace pressure was controlled at 0.55MPa and the ammonia flow rate was 0.5Nm³ / h. The temperature was raised to 540℃ and held for 3.5h. After cooling in the furnace, it was taken out, so that a uniform and dense nitriding layer was formed on the surface of the bushing body 1. The nitrided bushing body 1, along with the outer skeleton 2, inner skeleton 3, and retaining ring 6, undergo phosphate surface treatment, following these steps in sequence: ① Degreasing: Immerse the workpiece in a degreasing solution prepared at a mass ratio of 1:4 (degreasing solution: tap water), with a pH of 13.5 and a solution temperature of 65℃, for 500 seconds to thoroughly saponify and remove oil stains from the workpiece surface; ② Washing: Rinse with room temperature tap water for 30 seconds to remove residual degreasing solution from the workpiece surface; ③ Rust Removal: Immerse in a rust removal solution prepared at a mass ratio of 2:1 (hydrochloric acid: tap water), with a pH of 1.5, for 500 seconds at room temperature to remove oxide scale and rust from the workpiece surface; ④ Secondary Washing: Rinse with room temperature tap water for 30 seconds to remove residual acid; ⑤ Surface Conditioning: Immerse the workpiece in a surface conditioner... In the preparation of the solution, the surface preparation solution is prepared according to the mass ratio of surface preparation agent to tap water = 1:100, pH value 8.5, and treated at room temperature for 45s to activate the metal surface and provide uniform crystal nuclei for phosphating crystallization; ⑥ Phosphating: Immerse in the phosphating solution, the mass ratio of phosphating agent to tap water is 7:100, pH value 2.2, solution temperature 88℃, soak for 500s, control the ratio of total acidity to free acidity (acid ratio) to 6.5, and form a uniform and dense zinc phosphate phosphating film on the workpiece surface; ⑦ Cold water wash: Rinse with room temperature clean water for 20s; ⑧ Three water washes: Rinse with deionized water for 20s to thoroughly remove residual phosphating solution and soluble salts; ⑨ Drying and rust prevention: Place in a 100℃ hot air circulating oven to dry for 10min, and then spray a thin layer of rust-preventive oil for later use.

[0053] S2: Using the lip sheet formulation and its production process for enhancing the wear resistance of the lip, which was previously applied for by the applicant and has the publication number CN118909370B, a PTFE sintered blank lip sheet was prepared.

[0054] The sintered blank lip is clamped on a precision CNC lathe, and an annular recirculation thread with a helix angle of 80°~85° is machined on the sealing working surface of the main lip 4, with a thread depth of 0.03mm and a pitch of 0.5mm. Finally, it is precisely sliced ​​according to the designed axial thickness to obtain the finished main lip 4 and secondary lip 5 respectively.

[0055] S3: Preparation of AEM rubber compound. AEM acrylate raw rubber is fed into an open mixing mill, with the roller temperature controlled at 55℃. It is first plasticized for 2 minutes. Vulcanizing agents, accelerators, antioxidants, and other compounding agents are added according to the industry-standard formula. After uniform mixing, the roller gap is adjusted to 0.5mm, and the mixture is passed through a thin pass three times to ensure thorough dispersion of the rubber compound and additives. Finally, the roller gap is adjusted, and sheets are extruded to a thickness of 4mm and a width of 60mm. The sheets are then left to stand at room temperature for 16 hours for later use. The rested sheets are fed into a cold-feed extruder to extrude rubber strips. The extrusion pressure is set to 40MPa, the extrusion speed to 15m / min, and the take-up speed to 12m / min. The barrel temperature is controlled in sections: 60℃ for the inlet barrel, 65℃ for the middle barrel, and 70℃ for the outlet barrel. Uniform, dense, and bubble-free rubber strips are obtained and used for molding the first rubber layer 11 and the second rubber layer 21, respectively.

[0056] S4: Preparation of the semi-finished oil seal body by split vulcanization molding: The outer skeleton 2, inner skeleton 3, main lip 4, and secondary lip 5 are positioned into the vulcanization mold cavity according to the design. Silicone sealant is evenly applied to the assembly gap between the clamped ends of the main lip 4 and secondary lip 5 and the outer skeleton 2 and inner skeleton 3 to fill the assembly gap. Then, the second layer of adhesive strip 21 is placed in, and after the mold is closed, it is sent to a flat vulcanizing machine. The vulcanization temperature is set to 170℃ and the vulcanization pressure to 15MPa. The temperature and pressure are maintained for 300s to complete the first hot-press vulcanization. After the mold is opened and the part is removed, the edges are peeled, the adhesive is scraped, the edges are precisely trimmed, and the part is cleaned by compressed air blowing to completely remove the vulcanization flash and excess adhesive. The trimmed part is placed in a programmable oven for secondary vulcanization: the temperature is first raised to 160℃ and held for 20 minutes, then the temperature is raised to 175℃ and held for 270 minutes. After the program is completed, the part is cooled to room temperature with the oven to obtain the semi-finished oil seal body. Preparation of rubber-coated bushing: Using the same primary and secondary vulcanization process parameters as described above, the first rubber layer 11 and the bushing body 1 are molded and vulcanized together, so that the first rubber layer 11 is firmly bonded to the inner circumferential surface, air side end face and part of the outer circumferential surface of the bushing body 1, thus obtaining the rubber-coated bushing.

[0057] S5: Finished Product Assembly. A vertical pre-forming machine is used to hot-press and shape the free ends of the main lip 4 and auxiliary lip 5 within the semi-finished oil seal body. The shaping temperature is 130℃, and the temperature is maintained for 45 seconds to ensure that the lips are stably tilted towards the oil side at the designed angle. After shaping, a coaxial pressing fixture is used to smoothly press the rubber-coated bushing into the semi-finished oil seal body, ensuring that the lips of the main lip 4 and auxiliary lip 5 are evenly fitted to the outer circumferential surface of the bushing body 1. Finally, the retaining ring 6 is pressed and fixed to the end of the bushing body 1 near the oil side. After passing the airtightness test, appearance and dimensional inspection, the finished oil seal is obtained.

[0058] Example 2

[0059] This embodiment uses a novel small-sized oil seal with limited parameter range. The specific steps are basically the same as in Embodiment 1, with the key process parameters adjusted as follows:

[0060] Nitriding treatment: furnace pressure 0.5MPa, ammonia flow rate 0.4Nm³ / h, heat treatment at 540℃ for 3h;

[0061] Phosphating treatment: Degreasing temperature 60℃, time 450s; Rust removal time 450s; Surface conditioning time 30s; Phosphating temperature 85℃, time 450s, acid ratio 6;

[0062] PTFE preparation: cold pressing pressure 20MPa, sintering temperature 370℃, holding time 2h;

[0063] Rubber compound preparation: sheet thickness 3mm, width 50mm; extrusion speed 10m / min, retraction speed 8m / min; inlet cylinder 58℃, intermediate cylinder 63℃, outlet cylinder 68℃;

[0064] Vulcanization process: First vulcanization temperature 165℃, pressure 12MPa, time 240s; Second vulcanization temperature 157℃ for 20min, temperature 172℃ for 270min;

[0065] Lip pre-formation: Temperature 120℃, hold for 30 seconds.

[0066] Example 3

[0067] This embodiment uses the upper limit of the parameter range to prepare a large-size heavy-duty oil seal. The specific steps are basically the same as in Example 1, with the key process parameters adjusted as follows:

[0068] Nitriding treatment: furnace pressure 0.6MPa, ammonia flow rate 0.6Nm³ / h, heat treatment at 540℃ for 4h;

[0069] Phosphating treatment: Degreasing temperature 70℃, time 600s; Rust removal time 600s; Surface conditioning time 60s; Phosphating temperature 90℃, time 600s, acid ratio 7;

[0070] PTFE preparation: cold pressing pressure 30MPa, sintering temperature 390℃, holding time 4h;

[0071] Rubber compound preparation: sheet thickness 6mm, width 70mm; extrusion speed 20m / min, retraction speed 15m / min; inlet cylinder 62℃, intermediate cylinder 67℃, outlet cylinder 72℃;

[0072] Vulcanization process: First vulcanization temperature 175℃, pressure 18MPa, time 360s; Second vulcanization temperature 163℃ for 20min, temperature 178℃ for 270min;

[0073] Lip pre-formation: Temperature 150℃, hold for 60 seconds.

[0074] Test data: To verify the sealing performance and wear resistance of the oil seals prepared by the process of this invention, an RT-2-PCD type oil seal bench testing machine was used to conduct simulated working condition tests on oil seal samples with specifications of 88.5mm×123mm×14mm prepared in any of Examples 1-3.

[0075] 1. Test conditions:

[0076] The test shaft diameter was Φ89mm, the surface roughness was Ra1.2μm, the surface hardness was 43HRC, and the shaft runout was 0.15mm. The sealing medium was 85W / 90 gear oil, and the test oil volume was 4kg. The test speed was 500r / min, and the shaft rotation included both right-hand and left-hand rotation. The test cycle was as follows: 14h of continuous operation at room temperature, 6h of operation at 120℃, and 4h of cooling down, which constituted one cycle, with a total test duration of 240h. In the later stage of the test, a mud and water spray condition was added to verify the dustproof and mud-resistant performance of the oil seal.

[0077] 2. Experimental Procedure:

[0078] Install the test shaft and oil seal sample, adjust the shaft eccentricity to the set value, and write the operation program; start the test bench and run it continuously according to the set cycle system. During the test, observe in real time whether the oil seal leaks; after the test, remove the oil seal sample and test shaft, and observe the wear of the lip and the wear of the test shaft surface.

[0079] 3. Experimental Results and Conclusions:

[0080] After 240 hours of continuous bench testing under high and low temperature cycling, bidirectional rotation, and slurry conditions, the oil seal produced in the above embodiment showed no leakage throughout the entire process. Disassembly and inspection revealed no obvious wear marks on the lips of the main and auxiliary lips, no abnormal wear on the mating surfaces of the test shaft, no peeling of the first adhesive layer from the bushing body, and no rust or erosion deformation on the retaining ring. The test results demonstrate that the new oil seal produced using the process of this invention exhibits high sealing reliability, excellent wear resistance, and strong environmental resistance, fully meeting the requirements for long-life operation under complex working conditions.

[0081] 4. The experimental procedure is shown in Tables 1-2 below:

[0082] Table 1

[0083] Table 2

[0084] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A manufacturing process for a novel oil seal, the novel oil seal comprising a bushing body (1), a first adhesive layer (11) vulcanized on the surface of the bushing body (1), an outer skeleton (2) and an inner skeleton (3) axially sleeved on the outer periphery of the bushing body (1), a main lip (4) and a secondary lip (5) clamped and vulcanized and bonded between the outer skeleton (2) and the inner skeleton (3) and stacked thereon, a second adhesive layer (21) vulcanized and connected to the outer periphery of the outer skeleton (2), and a retaining ring (6) fixedly sleeved on the end of the bushing body (1), characterized in that, The aforementioned production process includes the following steps: S1: Metal parts are manufactured by stamping, including bushing body (1), outer skeleton (2), inner skeleton (3) and retaining ring (6); the manufactured metal parts are deburred, cleaned and then subjected to phosphating surface treatment. S2: The main lip (4) and the secondary lip (5) are obtained by pressing and sintering the mixed powder based on PTFE. After the angled annular thread is machined on the surface of the main lip (4), the main lip (4) and the secondary lip (5) are sliced. S3: AEM rubber is extruded after open milling to obtain the first rubber layer (11) and the second rubber layer (21). S4: Position the outer skeleton (2), inner skeleton (3), main lip (4) and secondary lip (5) into the vulcanization mold, add the second adhesive layer (21) and perform hot-press vulcanization. After demolding, perform surface treatment and then perform secondary vulcanization to obtain the oil seal body semi-finished product. Using the same vulcanization process as the oil seal body semi-finished product, connect the first adhesive layer (11) to the surface of the bushing body (1) to obtain the rubber-coated bushing. S5: Assemble the rubber-coated bushing, the semi-finished oil seal body and the retaining ring (6) to obtain the finished oil seal.

2. The manufacturing process of the novel oil seal as described in claim 1, characterized in that: In S1, the bushing body (1) needs to be nitrided before phosphating surface treatment.

3. The manufacturing process of the novel oil seal as described in claim 1, characterized in that: In S1, the phosphating surface treatment includes degreasing, water washing, rust removal, secondary water washing, surface conditioning, phosphating, cold water washing, tertiary water washing, drying, and rust prevention performed sequentially.

4. The manufacturing process of the novel oil seal as described in claim 3, characterized in that: In the degreasing process, the degreasing solution is prepared in the following proportions by mass: Degreasing solution: tap water = 1:4, degreasing solution pH value: 13~14, degreasing solution temperature: 60℃-70℃, degreasing time: 450s~600s; In the rust removal process, the rust removal solution is prepared in the following proportions by mass: Hydrochloric acid: tap water = 2:1; rust remover pH value: 1~2; rust remover temperature: room temperature; rust removal time: 450s~600s. In the aforementioned table conditioning solution, the mass ratio of the table conditioning solution is as follows: Surface conditioning solution: tap water = 1:100, pH value of surface conditioning solution: 8~9, surface conditioning temperature: room temperature, surface conditioning time: 30~60s; In the phosphating process, the phosphating agent is formulated in the following proportions by mass: Phosphating agent: tap water = 7:100, phosphating agent pH value: 2~2.5, phosphating temperature: 85℃~90℃, phosphating time: 450s~600s, phosphating acid ratio: 6~7.

5. The manufacturing process of the novel oil seal as described in claim 1, characterized in that: In S3, the open mixing is carried out using a rubber mixing mill, and the sheet is produced at least 3 times with a gap of 0.5mm, with a thickness of 3-6mm and a width of 50-70mm. The extrusion bar is made using an extrusion machine with an extrusion pressure of 40 MPa, an extrusion speed of 10-20 m / min, a take-up speed of 8-15 m / min, an inlet barrel temperature of 58℃-62℃, an intermediate barrel temperature of 63℃-67℃, and an outlet barrel temperature of 68℃-72℃.

6. The manufacturing process of the novel oil seal as described in claim 1, characterized in that: In step S4, the surface treatment includes edge tearing, adhesive scraping, edge trimming, and air spray cleaning.

7. The manufacturing process of the novel oil seal as described in claim 1, characterized in that: In S5, before assembly, a warm air blower or a vertical pre-forming machine can be used to bend the free ends of the main lip (4) and the secondary lip (5) to the oil side for pre-forming.

8. The manufacturing process of the novel oil seal as described in claim 2, characterized in that: The nitriding treatment is performed using a nitriding furnace; The nitriding conditions included: furnace pressure of 0.5 MPa to 0.6 MPa and ammonia flow rate of 0.4 nm. 3 / h~0.6nm 3 / h, keep warm at 540℃ for 3h~4h.

9. The manufacturing process of the novel oil seal as described in claim 1, characterized in that: In step S4, the secondary vulcanization is performed using a programmable oven; The secondary vulcanization conditions include: maintaining the temperature inside the chamber at 157℃~163℃ for at least 20 minutes, and maintaining the temperature at 172℃~178℃ for at least 270 minutes.

10. The manufacturing process of the novel oil seal as described in claim 1, characterized in that: In S4, the clamped ends of the main lip (4) and the secondary lip (5) when they are positioned in the vulcanizing mold are coated with sealant at the gap between them and the outer and inner skeletons.

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