V-shaped sealing ring manufacturing method, mold, product and shrinkage rate prediction method

Abstract

The invention discloses a V-shaped sealing ring manufacturing method, a mold, a product and a shrinkage rate prediction method. The V-shaped sealing ring manufacturing method comprises the following steps: baking a fluororubber cloth clamping rubber material to obtain a pre-dried fluororubber cloth clamping rubber material; a mold is heated to a set heating temperature, a mold cavity is filled with the pre-dried fluororubber cloth clamping sizing material, heat preservation is conducted under the specified pressure, the set time is reached, the fluororubber cloth clamping sizing material is taken out and trimmed, and a semi-finished pre-pressed part is obtained; the semi-finished pre-pressed part is put into a mold to be subjected to vulcanization operation, heat conduction operation is conducted on the circumferential surface of the mold, and overflow rubber of the semi-finished pre-pressed part in a mold cavity is guided out; and maintaining the mold closing pressure of the mold, forcibly cooling the mold to a set cooling temperature, and opening the mold to take out a finished product. According to the manufacturing method disclosed by the invention, a series of difficult problems of manufacturing the oversized fluororubber cloth-clamped V-shaped sealing ring are accurately solved through a manufacturing process of pre-baking, medium-temperature pre-forming, circumferential heat conduction vulcanization, overflow pressure control and forced cooling under pressure in cooperation with a special mold and a scientific shrinkage rate prediction model.

Description

Technical Field

[0001] This invention relates to the field of polymer material processing technology, specifically to a method for manufacturing a V-shaped sealing ring, a mold, a product, and a method for predicting shrinkage rate. Background Technology

[0002] Large hydraulic cylinders are the core of a piling vessel's power system. They must operate long-term in the highly corrosive marine environment characterized by high salt spray, high humidity, and wide temperature variations (-20℃ to 45℃), and withstand harsh conditions such as 250 bar high pressure and heavy-duty, off-center alternating loads. Currently, the main seals of the piling vessel's main hydraulic cylinders are mostly made of cotton / nitrile rubber. However, cotton fibers are difficult to adapt to the harsh marine environment, resulting in a seal lifespan generally less than 5 years. The transportation and downtime costs incurred for each repair exceed 2 million yuan, which cannot meet the requirement of a 20-year lifespan for the vessel itself.

[0003] To address the aforementioned issues, Chinese patent ZL202510955290.3 invented a fluororubber-reinforced fabric material for large hydraulic cylinder V-group seals and its preparation method. However, in the process of manufacturing ultra-large-sized seals (piston rod seal diameter up to 1120mm, piston seal diameter up to 1600mm), the manufacturing challenges of achieving high performance and high consistency for ultra-large-sized seals are encountered. Specifically, the macroscopic and microscopic dimensional accuracy, material uniformity across the entire ring, and performance stability are difficult to control. The specific shortcomings are as follows:

[0004] 1. Difficulty in controlling the dimensional accuracy of large-size seals: The traditional manufacturing process of fluororubber-reinforced fabric V-rings suffers from problems such as unstable dimensional shrinkage, significant anisotropy, and poor product consistency. For ultra-large seals with a diameter of 1.6 meters, the dimensional deviation is usually ±5mm to ±15mm, which is difficult to meet the application requirements.

[0005] 2. Difficulty in accurately controlling the amount of material fed: Rubber products have good fluidity, and excess rubber is generally discharged through the overflow tank. The amount of material fed should be 105-110% of the final product. However, fabric-reinforced rubber uses fabric as the skeleton material, which does not have fluidity and cannot overflow. Insufficient material feeding will result in insufficient rubber in the vulcanized product, while excessive material feeding will cause the product height and design angle dimensions to exceed the requirements.

[0006] 3. Difficulty in adapting to the difference in dry heat shrinkage of fibers: Traditional cylinder V-group seals use rubber / cotton fabric. Cotton fabric has a heat shrinkage of almost 0% at 150℃; while the polyester fiber used in fluororubber-reinforced fabric, even after heat setting, still has a residual shrinkage rate of 3-8% at 150℃, which is much higher than that of cotton fiber. The design experience of traditional cotton fabric-reinforced rubber is no longer applicable.

[0007] 4. Difficulty in quantitatively controlling shrinkage influencing factors: The rubber content, volatile matter, fabric type, feed amount, mold closing pressure, and vulcanization thermal expansion pressure are all key factors affecting the shrinkage of seals. Although existing technologies have recognized these factors, they lack quantitative control methods and rely more on experience and trial and error, making it impossible to accurately predict and compensate for shrinkage.

[0008] 5. Difficulty in ensuring uniformity and consistency of vulcanization: High-end equipment such as ultra-long hydraulic cylinders impose stringent requirements on ultra-large sealing components, demanding zero leakage for 20 years. This necessitates consistent vulcanization and performance within a 3-5mm circumferential dimension, requiring uniform temperature throughout the mold cavity. However, fabric-reinforced V-ring seals are narrow-section rubber products. During vulcanization in traditional flat vulcanizing machines, the top and bottom surfaces of the mold are the heated surfaces, while the central circumferential surface is the heat dissipation surface. Narrow-section products cannot meet the technical requirement of a heated area greater than twice the heat dissipation area, resulting in significant temperature gradients within the mold cavity. This makes it difficult to guarantee consistent performance and dimensions in both the height and circumferential directions. Summary of the Invention

[0009] The purpose of this invention is to overcome the shortcomings of the aforementioned background technology and provide a method for manufacturing V-shaped sealing rings, molds, products, and shrinkage prediction methods that offer precise size control, precise material feeding control, good adaptability to differences in fiber dry heat shrinkage, quantitative control over shrinkage influencing factors, and guarantee of vulcanization uniformity and consistency.

[0010] To achieve this objective, the V-shaped sealing ring manufacturing method designed in this invention includes the following steps: baking the fluororubber-lined fabric compound to obtain a pre-dried fluororubber-lined fabric compound; heating the mold to a set heating temperature, filling the pre-dried fluororubber-lined fabric compound into the mold cavity, maintaining the temperature under a specified pressure for a set time, removing and trimming the fluororubber-lined fabric compound to obtain a semi-finished pre-compressed part; placing the semi-finished pre-compressed part into the mold for vulcanization, performing heat conduction on the circumferential surface of the mold, and draining the overflowing material from the semi-finished pre-compressed part in the mold cavity; maintaining the mold closing pressure, forcibly cooling the mold to a set cooling temperature, and opening the mold to remove the finished part.

[0011] Furthermore, the method for baking the fluororubber-backed fabric material to obtain a pre-dried fluororubber-backed fabric material includes baking the fluororubber-backed fabric material at 100-120°C for 1.5-2.5 hours.

[0012] Furthermore, the set heating temperature is 90-120℃, the specified pressure is 30-35MPa, the set time is 3-5 minutes, and the set cooling temperature is 70-80℃.

[0013] Furthermore, the method for conducting heat on the circumferential surface of the mold includes: installing and fixing a heat-conducting oil jacket on the circumferential surface of the lower mold of the mold, and introducing heat-conducting oil with the same surface temperature as the mold into the heat-conducting oil jacket.

[0014] Furthermore, the method for exporting the overflow material of the semi-finished pre-compressed part in the mold cavity includes: opening multiple overflow holes in the upper mold of the mold, wherein the overflow holes are located in the center area of ​​the non-working surface of the V-shaped sealing ring.

[0015] Furthermore, the method for forcibly cooling the mold to a set cooling temperature includes: introducing heat-conducting oil with a temperature not exceeding 30°C into the heat-conducting oil jacket.

[0016] Furthermore, the present invention also provides a mold for implementing the V-shaped sealing ring manufacturing method, including an upper mold and a lower mold. A heat-conducting oil jacket is fixedly mounted on the circumferential surface of the lower mold. A plurality of overflow holes are opened in the upper mold. The heat-conducting oil jacket includes a circulating oil channel arranged inside the heat-conducting oil jacket and around the circumferential surface of the lower mold, as well as an oil inlet and an oil return port opened on the heat-conducting oil jacket and communicating with the circulating oil channel.

[0017] Furthermore, the overflow hole is located in the central region of the non-working surface of the V-shaped sealing ring.

[0018] Furthermore, the present invention also provides a V-shaped sealing ring product, which is manufactured by the V-shaped sealing ring manufacturing method described above.

[0019] Furthermore, the present invention also provides a method for predicting the shrinkage rate of the V-shaped sealing ring product, comprising the following steps: obtaining the intrinsic shrinkage rate β2 of the fluororubber-reinforced fabric compound under standard mold and constraint conditions and the target inner diameter d of the V-shaped sealing ring product; substituting the intrinsic shrinkage rate β2 of the fluororubber-reinforced fabric compound under constraint conditions and the target inner diameter d of the V-shaped sealing ring product into the calculation formula for the predicted shrinkage rate S of the V-shaped sealing ring product to obtain the predicted shrinkage rate S of the V-shaped sealing ring product; wherein, S=β2×(K+ C×d), K is the reference size effect coefficient, K=1.001; C is the inner diameter influence coefficient, C=-4.256×10 -5 / mm.

[0020] Furthermore, the method for obtaining the intrinsic shrinkage rate β2 of the fluororubber-lined compound under standard mold and constraint conditions includes: using a standard mold, obtaining a finished sample according to the V-shaped sealing ring manufacturing method, placing the finished sample under a set storage temperature and humidity for a set storage time, measuring the dimensions of the finished sample before and after storage, and obtaining the intrinsic shrinkage rate β2 of the fluororubber-lined compound under the standard mold and constraint conditions.

[0021] Furthermore, the set storage temperature is 23±2℃, the set storage humidity is 45%~55%, and the set storage time is 168±2h.

[0022] The beneficial effects of this invention are as follows: This invention, through a manufacturing process of "pre-baking - medium-temperature pre-forming - circumferential heat-guided vulcanization - overflow pressure control - forced cooling under pressure," combined with a dedicated mold and a scientific shrinkage prediction model, precisely solves a series of problems in manufacturing ultra-large-sized fluororubber-reinforced fabric V-shaped sealing rings. First, the fluororubber-reinforced fabric compound is pre-baked at 100-120℃ for 1.5-2.5 hours, effectively removing volatile components from the compound and avoiding dimensional deviations caused by the escape of volatile components during vulcanization. Then, through medium-temperature (90-120℃) pre-forming and physical trimming processes, the volume of the semi-finished pre-compressed part is precisely matched with the mold cavity volume, reducing subsequent vulcanization deformation redundancy. Combined with a post-vulcanization forced cooling to 70-80℃ shaping process, the product size is "locked" within the mold cavity, suppressing shrinkage and warping due to free cooling. Simultaneously, the prediction formula S=β2×(K+ C×d) based on the intrinsic shrinkage rate β2 can accurately compensate for dimensional shrinkage in advance. Through the synergistic effect of the aforementioned technologies, the dimensional accuracy of ultra-large fluororubber-reinforced fabric V-shaped sealing rings with a diameter of 1.6 meters has been successfully improved from over ±5mm in traditional processes to ±0.8mm, fully meeting the stringent consistency requirements for a 20-year lifespan of high-end equipment. Addressing the pain points of the fabric-reinforced material's lack of flowability and inability to drain through the overflow channel, this invention abandons the traditional direct feeding method and designs a pre-process of "medium-temperature pre-forming + physical trimming." This involves first pre-pressing the pre-dried rubber material at 30-35MPa pressure and 90-120℃ for 3-5 minutes, then physically trimming the pre-pressed part to ensure precise matching between the semi-finished product volume and the mold cavity volume before proceeding to the vulcanization process. This solution fundamentally avoids the problems of "insufficient material feeding leading to insufficient adhesive or excessive material feeding resulting in dimensional errors" in traditional processes, achieving precise control of the fabric-reinforced material feeding amount without relying on trial and error.

[0023] This invention regulates vulcanization thermal expansion pressure through two core technologies. First, it employs a 90-120℃ medium-temperature pre-forming process, significantly reducing the vulcanization initiation temperature and minimizing the thermal expansion of the rubber compound from room temperature to vulcanization temperature, thus reducing thermal expansion pressure at its source. Second, it designs a "fully closed - partially open" mold overflow structure, with multiple overflow holes in the center area of ​​the non-working surface of the upper mold's V-shaped sealing ring. This allows for precise removal of small amounts of overflowing rubber compound during vulcanization, achieving dynamic pressure balance within the mold cavity. This dual regulation stabilizes the mold cavity pressure within the equipment's clamping force range, preventing mold damage caused by excessive pressure and eliminating mold opening shrinkage and dimensional instability defects caused by pressure fluctuations. Addressing the temperature gradient problem in the mold cavity caused by the "top and bottom heating, circumferential heat dissipation" of traditional flat vulcanizing machines, this invention installs a fixed heat-conducting oil jacket on the circumferential surface of the lower mold. Heat-conducting oil with the same temperature as the mold surface is circulated into the jacket through circulating oil channels, transforming the original circumferential heat dissipation surface into a heating surface, achieving three-dimensional balanced heating from both top and bottom to the circumferential direction. This design enables narrow-section fabric-reinforced V-ring products to meet the technical requirement of "heated area > heat dissipation area by more than twice", completely eliminating the temperature gradient in the mold cavity and ensuring uniform vulcanization within a 3-5mm circumferential dimension. This, in turn, guarantees consistent performance in both the circumferential and height directions, providing core support for 20 years of zero leakage. After vulcanization, the invention maintains a constant mold closing pressure and forces the mold to cool using heat-conducting oil at a temperature not exceeding 30°C through a heat-conducting oil jacket. This allows the product to cool to 70-80°C under pressure constraint before the mold is opened. This pressure-constrained cooling process effectively releases internal stress in the product, preventing shrinkage, warping, and deformation caused by stress release during free cooling, thus precisely "fixing" the product dimensions. Simultaneously, standardized pre-baking, pre-forming, vulcanization, and cooling parameters ensure consistency in the manufacturing process across different batches, significantly improving product dimensional repeatability and batch stability, and reducing performance differences between batches.

[0024] This invention breaks through the traditional mold design model that relies on trial and error based on experience, and provides a mathematical model for accurate prediction of shrinkage rate based on multi-factor coupling, namely S=β2×(K+ C×d). This model, by obtaining the intrinsic shrinkage rate β2 under standard mold and constraint conditions, combined with the target inner diameter d, can quantitatively calculate the shrinkage rate and perform mold size compensation design. The intrinsic shrinkage rate β2 must be obtained by strictly following the manufacturing method of this invention to prepare a sample, and then measuring it after being placed at 23±2℃ and 45%-55% relative humidity for 168±2 hours, ensuring the accuracy of the prediction model. This method significantly improves the first-time success rate of large and expensive mold design, avoids the cost waste of repeated mold repairs, and significantly improves the economic efficiency of mold design.

[0025] In summary, this invention achieves uniform vulcanization control through a circumferential heat-guiding oil jacket, dimensional stability control through pressure-constrained cooling, and dimensional accuracy control through a shrinkage prediction model, comprehensively ensuring the high performance consistency of the fluororubber-reinforced fabric V-shaped sealing ring. Uniform vulcanization quality ensures a strong bond between the rubber and the fabric skeleton, avoiding localized performance weaknesses; precise dimensional accuracy guarantees a tight seal surface, preventing seal failure due to dimensional deviations. Ultimately, this enables the product to withstand the harsh operating conditions of high salt spray, high humidity, wide temperature variations, and 250 bar high-pressure alternating loads in the ocean, achieving a service life equivalent to 20 years for ships. It completely solves the problem of traditional cotton / nitrile rubber seals failing within 5 years, significantly reducing users' maintenance and transportation costs, downtime losses, and improving equipment reliability. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments disclosed in this invention, the accompanying drawings of the embodiments will be briefly described below. These drawings are for illustrative purposes only and are not intended to limit the scope of protection of this invention.

[0027] Figure 1 This is a half-sectional view of the manufacturing structure of the V-shaped sealing ring in this invention along the axial direction.

[0028] Wherein, 1—upper mold, 2—lower mold, 3—heat transfer oil jacket (3.1—upper jacket, 3.2—lower jacket, 3.3—circulating oil channel, 3.4—static sealing ring, 3.5—oil inlet, 3.6—oil return port), 4—V-shaped sealing ring, 5—overflow hole. Detailed Implementation

[0029] The technical solutions (including preferred technical solutions) of the present invention will be further described in detail below with reference to the accompanying drawings and by way of listing some optional embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. 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. In the description of the present invention, it should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0030] Example 1

[0031] This invention provides an embodiment of a method for manufacturing a V-shaped sealing ring:

[0032] This embodiment applies to the manufacturing method of extra-large fluororubber-reinforced fabric V-shaped sealing rings, which can solve problems such as poor dimensional accuracy, difficulty in controlling the amount of material fed, and uneven vulcanization pressure and temperature in traditional processes. Specifically, it includes the following steps:

[0033] Step 1: Pre-drying treatment of fluororubber-reinforced fabric at medium temperature

[0034] The volatile components in fluororubber-reinforced fabric (such as moisture, low molecular weight components, and processing aids like HT-290 wax) are one of the main causes of uncertain shrinkage during and after vulcanization. This step precisely controls the volatile content through preheating pretreatment. The specific process conditions are: baking the cut fluororubber-reinforced fabric compound at 100-120℃ for 1.5-2.5 hours, with the preferred process being 110℃ × 2 hours (the preferred temperature is determined based on the boiling point of the volatile components and the scorch time of the compound). This treatment reduces and stabilizes the volatile components in the compound within a very low and predictable range, eliminating the random influence of this variable on vulcanization shrinkage.

[0035] Step 2: Medium-temperature pre-forming process of fluororubber-reinforced fabric V-shaped sealing rings

[0036] The core of this step is to solve the problems of precise control of the amount of fabric reinforcement material fed in and excessive vulcanization thermal expansion pressure. The specific implementation steps are as follows:

[0037] Mold preheating: Heat the vulcanizing mold and keep it constant at 90-120℃, preferably 110℃;

[0038] Precise filling and pre-pressing: Take the pre-dried fluororubber reinforced fabric and weigh it at 1.05 times the mass calculated based on the material density and mold cavity volume. Fill it into the mold cavity while maintaining the same temperature as the mold. Apply a pressure of 30-35 MPa and keep it warm for 3-5 minutes under this pressure.

[0039] Trimming and Shaping: Remove the pre-pressed semi-finished product and trim off any excess material that has overflowed under pressure, ensuring that the volume of the semi-finished product at the pre-forming temperature is precisely equal to the volume of the steel mold cavity at that temperature. This process enables precise material feeding (by physically adjusting and matching the mold cavity volume) and controlled thermal expansion pressure (by raising the initial vulcanization temperature from room temperature to the pre-forming temperature, significantly reducing thermal expansion pressure). Taking a subsequent vulcanization temperature of 165℃ as an example, the thermal expansion pressure can be reduced from approximately 130MPa to approximately 45MPa, close to the clamping force range of the vulcanizing machine, reducing the risk of mold opening shrinkage and cracking.

[0040] Step 3: Compression vulcanization process

[0041] A matching mold structure is used to achieve constant pressure control and uniform temperature field regulation. Specifically, this includes: utilizing the mold's "overall closed-partially open" structure, during the vulcanization heating stage, excess rubber material generated by the thermal expansion of the fluororubber-reinforced fabric material flows through 2-4 micro-overflow holes (5) with a diameter of 1-2 mm in the center area of ​​the non-working surface of the upper mold. Figure 1 (As shown) A small amount is discharged to release residual thermal expansion pressure, ensuring that the pressure inside the mold cavity is always equal to the clamping force set by the vulcanizing machine (30-35MPa); through the heat transfer oil jacket 3 on the side of the mold (as shown) Figure 1 (As shown) Introduce heat-conducting oil with the same temperature as the upper and lower hot plates to transform the circumferential heat dissipation surface into an active heating surface, thereby achieving three-dimensional balanced heating and eliminating the temperature gradient of the mold cavity.

[0042] Step 4: Constrained Cooling and Shaping

[0043] After vulcanization, the mold closing pressure is kept constant, the heating system is cut off, and low-temperature heat transfer oil with a temperature not exceeding 30°C is introduced into the heat transfer oil jacket 3 for forced cooling. After the product temperature drops to 70-80°C (close to the glass transition temperature of the polyester skeleton), the mold is opened to "lock" the product size and avoid deformation caused by free cooling.

[0044] Example 2

[0045] This invention provides a mold for implementing a method for manufacturing V-shaped sealing rings:

[0046] The mold designed in this embodiment can achieve stable control of vulcanization pressure, uniform temperature field, and overflow discharge function. The specific structure is as follows:

[0047] 1. Mold main structure: including upper mold 1 and lower mold 2. After the upper mold 1 and lower mold 2 are closed, they form a mold cavity that matches the V-shaped sealing ring, which is used to accommodate the pre-formed fluororubber-reinforced fabric semi-finished product.

[0048] 2. Partially Open Overflow Structure: In the central area of ​​the non-working surface of the V-shaped seal ring corresponding to the upper mold 1, such as... Figure 1 As shown, there are 2-4 micro overflow holes (overflow hole 5) with a diameter of 1-2 mm. This structure macroscopically closes the mold cavity to ensure the density of the rubber compound, and microscopically forms a controllable pressure relief channel, which can discharge a small amount of excess rubber compound during the vulcanization heating stage, release residual thermal expansion pressure, and only produce a small amount of rubber edge, which does not affect the product quality.

[0049] 3. Circumferential Heat Transfer Oil Jacket Structure: A heat transfer oil jacket 3 is fixedly installed on the circumferential surface of the lower mold 2. The heat transfer oil jacket 3 includes an upper jacket 3.1 and a lower jacket 3.2, which are fixed together to form a circulating oil channel 3.3. The circulating oil 3.3 is arranged circumferentially around the lower mold. The upper and lower jackets are respectively provided with an oil inlet 3.5 and an oil return port 3.6 communicating with the circulating oil channel 3.3. To prevent oil from overflowing from the heat transfer oil jacket 3, a static sealing ring 3.4 is also provided. When the upper and lower jackets are clamped, the static sealing ring 3.4 can deform to seal the gap between the upper and lower jackets. During the vulcanization stage, heat transfer oil with the same temperature as the mold surface is introduced, turning the circumferential heat dissipation surface into a heat receiving surface; during the cooling stage, low-temperature heat transfer oil is introduced to achieve forced cooling of the mold. This structure can eliminate the temperature gradient in the mold cavity and ensure the uniformity of vulcanization and the stability of cooling.

[0050] Example 3

[0051] This invention provides a V-shaped sealing ring product:

[0052] The V-shaped sealing ring product provided in this embodiment is manufactured using the manufacturing method of Embodiment 1 and the mold of Embodiment 2. It is suitable for harsh working conditions such as the main hydraulic cylinder of a 150m-class piling vessel. The specific parameters and performance are as follows:

[0053] 1. Product Specifications: Includes two core specifications, adaptable to different sealing parts of the main hydraulic cylinder of piling vessels. The target dimensions for the V-ring seal used for piston rod sealing are Φ1118.1mm × Φ1171.9mm × 20.6mm. The target dimensions for the V-ring seal used for piston sealing are Φ1601.5mm × Φ1548.5mm × 20.6mm.

[0054] 2. Product materials: The product is made of fluororubber-reinforced fabric with a pre-treated polyester fiber fabric as the skeleton. The rubber and fabric are firmly bonded together, eliminating the risk of delamination.

[0055] 3. Product Performance Advantages: High Dimensional Accuracy: After being stored in an environment of (23±2)℃ and (50±5)% relative humidity for 7 days, the measured inner diameter of the piston rod seal is 1118.05mm, and the measured inner diameter of the piston seal is 1601.45mm, with a dimensional accuracy within ±0.8mm. Good Batch Consistency: The dimensional difference (maximum value - minimum value) of the inner diameter of three consecutively produced products is less than 0.5mm. Excellent Structural Integrity: Free from defects such as shrinkage cracks, bubbles, and uneven flash, exhibiting good density. Strong Adaptability to Working Conditions: It can withstand marine high salt spray, high humidity, and wide temperature variation (-20℃~45℃) environments, withstand 250bar high pressure and heavy-duty off-center alternating loads, and has a service life of up to 20 years, the same as that of ships.

[0056] Example 4

[0057] A method for predicting the shrinkage rate of V-shaped sealing ring products (including mold size design) is provided:

[0058] First, this embodiment provides a shrinkage rate prediction method based on multi-factor coupling, which can accurately predict the shrinkage rate of ultra-large V-shaped sealing rings, thereby guiding mold size design. The specific steps are as follows:

[0059] Step 1: Determination of basic parameters: First, the intrinsic shrinkage rate β2 of the fluororubber-reinforced fabric material under process constraints of the standard mold is determined. The determination steps are as follows: Dry the fluororubber-reinforced fabric sample in a hot air environment at 110℃ for 2 hours, weigh it according to the calculated mass, pre-compress it for 3 minutes at 110℃ and 30MPa, and trim off excess rubber; vulcanize it for 10 minutes at a clamping pressure of 30MPa and a temperature of 165℃ for 10 minutes, and after vulcanization, keep the mold closing pressure and cool it to 80℃ before opening the mold; place the sample in an environment at 23℃ and 50% relative humidity for 7 days, and calculate it according to the formula β(%)=[(standard size of mold cavity - actual size of product) / standard size of mold cavity]×100%, and the measured β2=0.2126% (the standard mold specification is 200mm×200mm×2mm).

[0060] Step 2: Construction and Calculation of Shrinkage Rate Prediction Model: Construct a shrinkage rate prediction model to reveal the quantitative relationship between the overall shrinkage rate S, β2, and the product inner diameter d.

[0061] The prediction model formula is S=β2×(K+ C×d), where: S is the overall shrinkage rate to be predicted (%); d is the inner diameter of the target product (mm); K is the baseline size effect coefficient (fit value K≈1.001); and C is the inner diameter influence coefficient (fit value C≈-4.256×10⁻⁶). -5 / mm).

[0062] The specific source process for K and C is as follows: Existing mold products with various inner diameter specifications were selected (including six extra-large size products with inner diameter × outer diameter × height of 500×550×20.6mm, 2190×2270×31.5mm, 1750×1830×31.5mm, 2478×2558×31.5mm, 1210×1270×24.7mm, and 1200×1250×20mm, respectively). All were produced using the complete process of Example 1 of this invention (pre-drying, medium-temperature pre-forming, compression molding vulcanization, and constrained cooling), with three pieces produced for each specification. The inner diameter d of each specification was... K (Independent variable) and the corresponding measured shrinkage rate β k The dataset consists of 18 original data points (dependent variable), with the mean of the three corresponding items for each specification taken as valid data. The ratio y for each specification is calculated. k =β k / β2 (β2 is the intrinsic shrinkage of the standard specimen under constrained conditions, which has been determined to be 0.2126%). Using y k For dependent variable, d K Using β2×(K+C×d) as the independent variable, a linear fitting equation was constructed. K and C were then solved using the least squares method to minimize the sum of squared deviations between the fitted and measured values. The fitting calculations yielded a reference size effect coefficient K≈1.001 and an inner diameter influence coefficient C≈-4.256×10⁻⁶. -5 / mm, the correlation coefficient R² of the fitted equation is >0.95, ensuring the reliability of the coefficient.

[0063] Specific calculation example (taking a 150m-class piling vessel seal as an example):

[0064] V-ring seal for piston rod sealing (d=1118.1mm): S=0.2126%×(1.001-0.00004256×1118.1)≈0.2027%;

[0065] V-ring seal for piston sealing (d=1601.5mm): S=0.2126%×(1.001-0.00004256×1601.5)≈0.1983%.

[0066] Based on the predicted shrinkage rate of the V-shaped sealing ring for the piston rod seal and piston seal described above, the mold dimensions are designed as follows: The mold cavity dimensions are calculated using the following formula: Mold cavity dimensions = Target product dimensions / (1-S)

[0067] Specific design examples:

[0068] Mold for V-ring seal used for piston rod sealing: Inner diameter = 1118.1mm / (1-0.002027)≈1120.37mm, Outer diameter = 1171.9mm / (1-0.002027)≈1174.28mm, Height = 20.6mm (shrinkage effect ignored);

[0069] Mold for V-shaped seal ring used for piston sealing: Inner diameter = 1601.5mm / (1-0.001983)≈1604.67mm, Outer diameter = 1548.5mm / (1-0.001983)≈1551.57mm, Height = 20.6mm.

[0070] The mold designed and manufactured according to the above method was used to produce products. The actual shrinkage rate of the V-shaped sealing ring used for piston rod sealing was 0.203% (highly consistent with the predicted value of 0.2027%), and the actual shrinkage rate of the V-shaped sealing ring used for piston sealing was 0.199% (highly consistent with the predicted value of 0.1983%), proving that the prediction method and mold design scheme are accurate and reliable.

[0071] To further highlight the technical advantages of this invention, a comparative verification was conducted using a set of parameters:

[0072] Reference proportion (V-shaped sealing ring for piston rod sealing, using the mold of the present invention but with conventional process): The product specifications are the same as those of the V-shaped sealing ring for piston rod sealing in Example 4 (target dimensions: inner diameter Φ1118.1mm × outer diameter Φ1171.9mm × height 20.6mm). The precision mold of the present invention is used directly, but the core process of the present invention is abandoned and a conventional vulcanization method is adopted: the fluororubber reinforced fabric is not dried in hot air at 110°C, and is directly filled into the mold after weighing. No medium-temperature pre-forming or trimming is performed. After vulcanization at 165°C for 10 minutes under a clamping pressure of 30MPa, the mold is opened directly and the hot product is allowed to cool freely at room temperature.

[0073] Reference results: After the product was left to stand, the inner diameter fluctuated greatly (Φ1110.4mm-Φ1119.8mm), and could not consistently reach the target size; the actual shrinkage rate fluctuated drastically between 1% and 0.1%, far deviating from the predicted 0.2%; severe radial shrinkage cracks appeared on the side and sealing lip of the product, the flash was thick and uneven, there were tiny air bubbles inside, poor density, soft feel, uneven hardness, and there was a risk of permanent deformation.

[0074] By comparing the proportions and embodiments, the technical effects of the present invention can be clearly seen as follows:

[0075] (1) Process and mold collaboration ensure dimensional accuracy: The technical value of this invention lies in the systematic collaboration between process and mold design, rather than the precision machining of a single mold. Even when using the precision mold designed by this invention, traditional processes still cannot produce qualified products due to the lack of core controls such as pre-drying, medium-temperature pre-forming, and constrained cooling. The mold accuracy is completely negated by the chaotic process. However, this invention achieves high-precision manufacturing of ultra-large size sealing parts through a complete set of process control, verifying the indispensability of the process solution.

[0076] (2) Multi-stage control to eliminate shrinkage uncertainty: Traditional processes cannot control variables such as volatile matter, thermal expansion pressure, and cooling deformation, which leads to uncontrolled intrinsic shrinkage rate and internal stress of the material, unpredictable shrinkage behavior, and fatal defects such as shrinkage cracks and bubbles in the product; This invention eliminates the influence of volatile matter through pre-drying, controls thermal expansion pressure through medium-temperature pre-forming, and locks in dimensions through constrained cooling, systematically stabilizing the shrinkage rate at an extremely low and predictable level, while ensuring the physical integrity of the product.

[0077] (3) Improve batch stability and working condition adaptability: Through the whole process control of pre-drying, pre-forming, three-dimensional uniform vulcanization and constrained cooling, this invention not only achieves high precision of single products, but also ensures batch consistency (the inner diameter difference of 3 consecutive products is <0.5mm), enabling the products to withstand the harsh working conditions of high salt spray in the ocean, wide temperature variation and high pressure alternating load, laying the foundation for a 20-year service life; while traditional process products have large size fluctuations and uneven performance, which cannot meet the long-term service requirements of high-end equipment.

[0078] In summary, this invention, through the synergistic innovation of "process control + precise prediction + specialized molds", has completely solved the manufacturing problem of ultra-large fluororubber-reinforced fabric V-shaped sealing rings, achieving a leap from "experience-based trial and error" to "precise controllability", and significantly improving product quality and manufacturing reliability.

[0079] It should be noted that the above description of the technical solutions is exemplary, and this specification may be embodied in different forms and should not be construed as limiting it to the technical solutions set forth herein. Rather, providing these descriptions will ensure that the disclosure of this invention is thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Furthermore, the technical solutions of this invention are defined only by the scope of the claims. The shapes, dimensions, ratios, angles, and figures used to describe aspects of this specification and the claims are merely examples, and therefore, this specification and the claims are not limited to the details shown. In the following description, detailed descriptions of relevant known functions or configurations will be omitted where it is determined that such detailed descriptions would unnecessarily obscure the focus of this specification and the claims. When using the terms "comprising," "having," and "including" as described in this specification, there may also be another part or other parts, and the terms used are generally singular but may also represent plural forms.

[0080] Finally, it should be noted that the above embodiments are merely representative examples of the present invention. Obviously, the present invention is not limited to the above embodiments and many variations are possible. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention should be considered within the protection scope of the present invention.

Claims

1. A method of manufacturing a V-seal, characterized by: The method comprises the following steps: roasting the fluororubber fabric material to obtain a pre-dried fluororubber fabric material; heating the mold to a set heating temperature, filling the pre-dried fluororubber fabric material into a mold cavity, maintaining at a specified pressure and reaching a set time, taking out and trimming the fluororubber fabric material to obtain a semi-finished product pre-pressing piece; placing the semi-finished product pre-pressing piece into the mold for vulcanization operation, conducting heat transfer operation on the circumferential surface of the mold, and guiding the overflow material of the semi-finished product pre-pressing piece in the mold cavity out of the mold; maintaining the mold clamping pressure, forcibly cooling the mold to a set cooling temperature, and opening the mold to take out the finished product piece.

2. The manufacturing method of the V-shaped sealing ring according to claim 1, wherein: The method for roasting the fluororubber fabric material to obtain a pre-dried fluororubber fabric material comprises: roasting the fluororubber fabric material at 100-120°C for 1.5-2.5 hours.

3. The manufacturing method of the V-shaped sealing ring according to claim 1, wherein: The set heating temperature is 90-120°C, the specified pressure is 30-35 MPa, the set time is 3-5 minutes, and the set cooling temperature is 70-80°C.

4. The manufacturing method of the V-shaped sealing ring according to claim 1, wherein: The method for conducting heat transfer operation on the circumferential surface of the mold comprises: installing a fixed heat conduction oil jacket (3) on the circumferential surface of the lower mold (2) of the mold, and introducing heat conduction oil with the same temperature as the mold surface temperature into the heat conduction oil jacket (3).

5. The manufacturing method of the V-shaped sealing ring according to claim 1, wherein: The method for guiding the overflow material of the semi-finished product pre-pressing piece in the mold cavity out of the mold comprises: opening a plurality of overflow holes (5) in the upper mold (1) of the mold, and the overflow holes (5) are located in the center area of the non-working surface of the V-shaped sealing ring (4).

6. The manufacturing method of the V-shaped sealing ring according to claim 4, wherein: The method for forcibly cooling the mold to a set cooling temperature comprises: introducing heat conduction oil with a temperature not exceeding 30°C into the heat conduction oil jacket (3).

7. A mold for implementing the manufacturing method of the V-shaped sealing ring according to any one of claims 1-6, comprising an upper mold (1) and a lower mold (2), characterized in that: The circumferential surface of the lower mold (2) is fixedly installed with a heat conduction oil jacket (3), the upper mold (1) is provided with a plurality of overflow holes (5), and the heat conduction oil jacket (3) comprises a circulating oil channel (3.3) arranged inside the heat conduction oil jacket (3) and around the circumferential surface of the lower mold (2), and an oil inlet (3.5) and an oil return (3.6) opened on the heat conduction oil jacket (3) and communicating with the circulating oil channel (3.3).

8. The mold for implementing a manufacturing method of a V-shaped sealing ring according to claim 6, wherein: The overflow holes (5) are located in the center area of the non-working surface of the V-shaped sealing ring (4).

9. A V-seal product, characterized by: It is made by the V-shaped sealing ring manufacturing method of any one of claims 1-6.

10. A method of predicting the shrinkage of a V-ring product according to claim 9, characterized in that: The method comprises the following steps: The intrinsic shrinkage β2 of the fluororubber fabric compound under the standard mold and constraint condition and the target inner diameter size d of the V-shaped sealing ring product are obtained; the intrinsic shrinkage β2 of the fluororubber fabric compound under the constraint condition and the target inner diameter size d of the V-shaped sealing ring product are brought into the calculation formula of the predicted shrinkage S of the V-shaped sealing ring product to obtain the predicted shrinkage S of the V-shaped sealing ring product; wherein S=β2×(K+C×d), K is a reference size effect coefficient, K=1.001; C is an inner diameter influence coefficient, C=-4.256×10 -5 / mm.

11. The method of predicting the shrinkage of a V-ring product according to claim 10, characterized in that: The method for obtaining the intrinsic shrinkage rate β2 of the fluororubber fabric material under the standard mold and the constraint condition comprises: using a standard mold, obtaining a finished product sample according to the V-shaped sealing ring manufacturing method, placing the finished product sample at a set parking temperature and a set parking humidity for a set parking time, measuring the size of the finished product sample before and after parking, and obtaining the intrinsic shrinkage rate β2 of the fluororubber fabric material under the standard mold and the constraint condition.

12. The method of predicting the shrinkage of a V-ring product according to claim 11, characterized in that: The set parking temperature is 23±2°C, the set parking humidity is 45%-55%, and the set parking time is 168±2h.

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