An oil-impervious mold core structure

Abstract

The utility model discloses a kind of oil seepage prevention die core structures, at least one annular sealing groove is arranged in the circumferential direction of the working section of die core body, and the detachable elastic sealing ring is embedded in the sealing groove, and the outer diameter of sealing ring is greater than the inner diameter of die cavity to form interference fit.The utility model realizes double sealing by replaceable sealing ring structure, solves the pollution and waste problem caused by traditional die core oil seepage, greatly reduces the oil seepage rate, and is especially suitable for high-pressure oil injection mould such as lubricating oil block.

Description

Technical Field

[0001] This utility model relates to the field of precision mold technology, and is particularly applicable to the oil-proof mold core structure that requires high-pressure oil injection, such as lubricating oil blocks and grease molding molds. Background Technology

[0002] In the molding and processing of oil-based products (such as lubricating oil blocks, greases, and rust-preventive oils), the sealing performance of the mold core and mold cavity is a key factor affecting product quality and production efficiency. Traditional mold cores often employ an integral metal structure, relying on precision machining to control the fit clearance between the mold core and mold cavity (typically 0.05-0.2mm). However, under high-pressure oil injection conditions, oil can still seep through these microscopic gaps, leading to product contamination, material waste, and mold scaling. Existing improvement solutions mostly use an integral rubber-coated mold core, which can improve sealing in the short term, but the entire mold core needs to be replaced after the rubber layer wears down, resulting in high maintenance costs. Industry test data shows that the traditional structure has an average oil leakage of 4.8ml per injection under an injection pressure of 10MPa, causing not only approximately 5% material loss but also requiring frequent shutdowns for mold cleaning. Furthermore, the carbonization of leaked oil residue exacerbates mold cavity wear, shortening mold life by more than 30%. Therefore, there is an urgent need for an oil-leakage-proof mold core structure that combines maintainability and high-pressure adaptability to fundamentally solve the series of problems caused by oil leakage. Utility Model Content

[0003] The technical problem to be solved by this utility model is to provide an oil-proof mold core structure. This utility model achieves double sealing through a replaceable sealing ring structure, which solves the pollution and waste problems caused by oil leakage in traditional mold cores, greatly reducing the oil leakage rate. It is especially suitable for high-pressure oil injection molds such as lubricating oil blocks.

[0004] This utility model is achieved through the following solution: an oil-proof mold core structure, including a mold core body, wherein the working section of the mold core body is provided with at least one annular sealing groove in the circumference, and a detachable elastic sealing ring is embedded in the sealing groove, wherein the outer diameter of the sealing ring is larger than the inner diameter of the mold cavity to form an interference fit.

[0005] The sealing ring has a trapezoidal cross-section, and the sealing groove has a matching trapezoidal groove cross-section.

[0006] The top of the sealing ring is provided with an annular lubrication reservoir, the depth of which is 1 / 5 to 1 / 4 of the total height of the sealing ring.

[0007] The sealing ring is made of oil-resistant elastic material with a Shore hardness of 70A-90A and a compression set of ≤15%.

[0008] The oil-resistant elastic material is hydrogenated nitrile rubber, fluororubber, or polytetrafluoroethylene composite material.

[0009] The outer surface of the sealing ring is provided with a spiral oil-guiding pattern, with a pattern depth of 0.1-0.3 mm and a pitch of 2-4 mm.

[0010] Two sealing rings are arranged axially on the mold core body, and the ratio of the distance L between the two sealing rings to the diameter of the mold core is 0.3 to 0.5.

[0011] The beneficial effects of this utility model are as follows:

[0012] 1. This utility model effectively solves the oil leakage problem of traditional mold core structures through an innovative sealing ring design. Compared with the integral sealing structure, the split replaceable sealing ring significantly reduces maintenance costs. After wear, only the sealing ring needs to be replaced to restore sealing performance, avoiding the scrapping of the entire mold core.

[0013] 2. The unique trapezoidal cross-section sealing ring, combined with an interference fit design, maintains a stable seal even under high-pressure conditions, significantly reducing oil leakage. Simultaneously, the special material of the sealing ring provides excellent oil resistance and deformation resistance, extending its service life. The optimized spiral oil guide pattern design ensures both sealing performance and reduces frictional loss.

[0014] 3. The double sealing ring layout provides double sealing protection, further enhancing the reliability of oil leakage prevention. This utility model has a simple and practical structure, which not only significantly improves the sealing effect but also reduces maintenance difficulty. It is particularly suitable for high-pressure oil injection molding dies such as lubricating oil blocks, and has obvious practical value and economic advantages. Attached Figure Description

[0015] Figure 1 is a front view cross-sectional view of the oil-proof mold core structure of this utility model.

[0016] Figure 2 is a schematic diagram of the A-scale structure of the oil-proof mold core structure of this utility model.

[0017] Figure 3 is a three-dimensional structural schematic diagram of a sealing ring for an oil-proof mold core structure according to this utility model.

[0018] Figure 4 is a front view cross-sectional view of the oil-proof mold core structure of this utility model in use.

[0019] In the figure: 1 is the mold core body, 2 is the sealing groove, 3 is the sealing ring, 31 is the lubrication oil reservoir, and 4 is the mold cavity. Detailed Implementation

[0020] The present invention will be further described below with reference to Figures 1-4, but the scope of protection of the present invention is not limited to the contents described.

[0021] Identical components are represented by the same reference numerals. It should be noted that the terms "front," "rear," "left," "right," "up," and "down" used in the following description refer to directions in the accompanying drawings, while the terms "inner" and "outer" refer to directions toward or away from the geometric center of a specific component, respectively. Furthermore, the accompanying drawings are all in a very simplified form and use non-precise ratios, and are only used to facilitate and clarify the purpose of illustrating the embodiments of this utility model.

[0022] Example 1

[0023] This embodiment provides a basic oil-proof mold core structure, as shown in Figures 1-4. This structure mainly comprises three core components: the mold core body 1, the sealing groove 2, and the sealing ring 3. The mold core body 1 is made of 45# high-quality carbon steel through quenching and tempering heat treatment, achieving a hardness of HRC28-32, ensuring both sufficient structural strength and good machinability. An annular sealing groove 2 with a width of 6±0.02mm and a depth of 5.5±0.02mm is machined into the working section of the mold core body 1 (i.e., the section that mates with the mold cavity 4). The bottom of the groove has a radius of 0.2mm, which effectively avoids stress concentration and extends the service life of the mold core.

[0024] The sealing ring 3 is manufactured using injection molding, and the material is hydrogenated nitrile butadiene rubber (HNBR) with a Shore hardness of 80A±3. In the ASTM D471 standard oil immersion test, this material exhibits a volume expansion rate of no more than 5% and a compression set (70℃×24h) ≤12%. The sealing ring 3 has an isosceles trapezoidal cross-section with an upper base of 5±0.05mm, a lower base of 6±0.05mm, and a height of 6±0.05mm. This special cross-sectional shape generates sealing forces in both radial and axial directions under pressure, significantly improving the sealing effect. During installation, after pressing the sealing ring 3 into the sealing groove 2, its outer diameter reaches 50.4±0.05mm, forming an interference fit of 0.38-0.42mm with the inner diameter of the standard mold cavity 4 (50+0.02mm). Verified by ANSYS finite element analysis, this interference fit can produce an elastic deformation of 0.12-0.18 mm under a working pressure of 5 MPa, which can ensure sealing performance without causing excessive wear.

[0025] As shown in Figures 2 and 3, an annular lubricating oil reservoir 31, 1.8±0.05mm wide and 1.2±0.03mm deep, is machined at the center of the top of the sealing ring 3. This reservoir can hold approximately 0.15ml of food-grade grease (compliant with NSF H1 standards). The outer surface of the sealing ring 3 is precision-engraved with a right-handed spiral oil guide pattern of 15° ± 1°, with a pattern depth of 0.2±0.02mm and a pitch of 3±0.1mm. This unique pattern design has a dual function: on the one hand, when a small amount of oil...

[0026] When liquid seeps into the sealing surface, the spiral grooves guide the oil back into the mold cavity along the thread direction; on the other hand, the grooves can store a small amount of lubricating oil, reducing the dynamic friction coefficient from 0.25 in the conventional structure to below 0.15. Actual measurement data shows that under continuous operation for 8 hours, the temperature of the sealing ring of this structure only increases by 12±2℃, far lower than the 35±5℃ temperature rise of ordinary O-ring structures.

[0027] Example 2

[0028] This embodiment features an optimized design for high-pressure conditions. Two sealing rings 3 are arranged axially on the mold core body 1, forming a double sealing guarantee. The mold core body 1 is made of 9Cr18MoV martensitic stainless steel, and undergoes vacuum quenching + deep cryogenic treatment + tempering heat treatment to achieve a hardness of HRC54-56, exhibiting excellent corrosion resistance and wear resistance. The working section has a diameter of 80±0.03mm and a surface roughness Ra≤0.4 μm. The spacing between the two sealing rings 3 is designed to be 32±0.05mm (calculated based on 0.4D). This spacing has been verified through fluid dynamics simulation to form a stable pressure buffer zone between the two sealing rings.

[0029] The front sealing ring 3a (near the oil inlet) is made of a composite material of polytetrafluoroethylene (PTFE) filled with 25% glass fiber. This material has a wear coefficient of only 0.12 in the ASTM D3700 standard test. Its cross-section is designed as an asymmetrical trapezoid (upper base 6±0.05mm, lower base 8±0.05mm), a special shape that better resists the axial impact force of high-pressure oil. The bottom of the sealing groove 2a has eight evenly distributed pressure-reducing micro-holes with a diameter of 0.3±0.02mm, arranged at a 45° angle. When the oil pressure suddenly rises to 20MPa, it can temporarily relieve pressure through the micro-holes, with the pressure relief flow rate controlled within 0.05ml / s, thus alleviating pressure peaks without affecting normal sealing performance.

[0030] The rear sealing ring 3b is made of fluororubber (FKM) with a hardness of 85A±3, maintaining good elasticity even at 200℃. Its top has a lubrication reservoir 31 with a width of 2±0.05mm and a depth of 1.5±0.05mm, pre-filled with high-temperature resistant molybdenum disulfide lubricant, allowing for an operating temperature range of -40℃ to 280℃. The two sealing rings employ a differentiated design: the front sealing ring 3a has a double-ended spiral pattern with a depth of 0.25±0.02mm and a pitch of 2.5±0.1mm on its outer surface; the rear sealing ring 3b has a single-ended spiral pattern with a depth of 0.15±0.02mm and a pitch of 3.5±0.1mm. This combined design allows the front sealing ring to bear approximately 70% of the pressure load, while the rear sealing ring serves as a safety redundancy.

[0031] In practical applications, when the system pressure reaches 15-20 MPa, the front sealing ring 3a will experience a shrinkage of 0.25-0.35 mm.

[0032] The elastic deformation occurs, at which point the subsequent sealing ring 3b begins to participate in the sealing. Actual measurement data from a petrochemical company shows that after 500 cycles of continuous operation under a pressure of 18±0.5MPa, the oil leakage rate stabilizes within the range of 0.18-0.22ml / cycle, and the wear difference between the two sealing rings is controlled between 0.03-0.05mm, proving the effectiveness of the pressure distribution mechanism.

[0033] In terms of maintenance, this embodiment innovatively adopts a "step-by-step replacement" strategy: when the wear of the front sealing ring 3a reaches 0.3mm, it is replaced and moved to the next position, and a new ring is installed in the front. This maintenance method can extend the overall service life of the sealing assembly by approximately 35-45% compared to complete replacement. For easy identification, the two sealing rings are marked with different colors: the front sealing ring 3a is yellow (RAL 1021), and the rear sealing ring 3b is blue (RAL 5015), with directional arrows laser-engraved on the end face. The replacement operation uses specialized installation tools and can be completed within 15±2 minutes, greatly reducing equipment downtime.

[0034] Although the technical solutions of this utility model have been described and enumerated in detail, it should be understood that modifications to the above embodiments or the adoption of equivalent alternatives are obvious to those skilled in the art. Such modifications or improvements made without departing from the spirit of this utility model are all within the scope of protection claimed by this utility model.

Claims

1. An oil barrier die core structure comprising a die core body (1), characterized in that, The working section of the mold core body (1) is provided with at least one annular sealing groove (2) in the circumferential direction. The sealing groove is embedded with a detachable elastic sealing ring (3). The outer diameter of the sealing ring (3) is larger than the inner diameter of the mold cavity (4) to form an interference fit.

2. The oil-proof mold core structure according to claim 1, characterized in that, The sealing ring (3) has a trapezoidal cross section, and the sealing groove (2) has a matching trapezoidal groove cross section.

3. The oil-proof mold core structure according to claim 1, characterized in that, The top of the sealing ring (3) is provided with an annular lubrication reservoir (31), the depth of which is 1 / 5 to 1 / 4 of the total height of the sealing ring.

4. An oil barrier core structure according to claim 1, wherein The sealing ring (3) is made of oil-resistant elastic material with a Shore hardness of 70A-90A and a compression set of ≤15%.

5. An oil barrier core structure according to claim 4, wherein The oil-resistant elastic material is hydrogenated nitrile rubber, fluororubber, or polytetrafluoroethylene composite material.

6. An oil barrier core structure according to claim 1, wherein The outer surface of the sealing ring (3) is provided with a spiral oil guide pattern with a pattern depth of 0.1-0.3 mm and a pitch of 2-4 mm.

7. An oil barrier core structure according to claim 1, wherein Two sealing rings (3) are arranged axially on the mold core body (1), and the ratio of the distance L between the two sealing rings to the diameter of the mold core is 0.3 to 0.5.

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