High-sealing-performance rotary joint and preparation process thereof

Abstract

The invention relates to the technical field of fluid conveying, and discloses a high-sealing-performance rotary joint and a preparation technology thereof.The rotary joint comprises a rotary joint body I and a rotary joint body II which is rotatably arranged, and a leakage early warning structure is arranged on the rotary joint body I; the structure comprises an early warning channel, a liquid accumulation groove used for collecting a trace amount of leaked fluid and an observation window installed outside. A two-way labyrinth type sealing structure is arranged on the outer side of the thrust ball bearing, so that the environmental adaptability is improved; according to the manufacturing technology, after assembly is completed through a low-temperature stress-free method, in-situ final machining is conducted on the device under the dynamic standard, specifically, a thrust ball bearing of the device serves as the dynamic standard to drive the rotating joint body II to rotate, and final micromachining is conducted on the dynamic sealing face. According to the invention, the assembly accumulative error is fundamentally eliminated, the dynamic sealing surface with ultrahigh geometric accuracy is obtained, the sealing performance and the operation safety of the rotary joint are obviously improved, and the service life of the rotary joint is obviously prolonged.

Description

Technical Field

[0001] This invention relates to the field of fluid transport technology, specifically to a high-sealing rotary joint and its manufacturing process. Background Technology

[0002] Rotary joints, as key components for transferring fluid media between stationary pipelines and rotating equipment, are widely used in many industrial fields such as papermaking, steelmaking, chemical engineering, and machine tool manufacturing. A typical rotary joint usually includes a rotary joint body that serves as a fixed housing, a rotary joint body rotatably inserted therein, rolling bearings for supporting rotation, and dynamic seals for preventing media leakage.

[0003] However, the reliability of existing rotary joints largely depends on the performance of dynamic seals. As vulnerable components, wear and failure of dynamic seals are inevitable, but the failure process is often sudden and unpredictable. In practical applications, once a leak occurs, high-pressure fluid not only flows out rapidly, but more seriously, it can infiltrate and erode the internal support bearings, leading to secondary failures such as lubrication failure and bearing burnout, ultimately causing unplanned downtime and significant economic losses. Existing designs generally lack a mechanism to provide early warning when seal failure occurs in its initial stages.

[0004] Furthermore, while some rotary joints may have simple dust covers or auxiliary seals to protect the bearings, these basic protective measures are insufficient to effectively prevent external contaminants from slowly infiltrating over time in harsh industrial environments filled with dust and moisture. They also cannot completely prevent the loss of internal lubricating grease under the centrifugal force of high-speed rotation. This inadequate protection of the bearing chamber accelerates bearing wear and limits the long-term reliability of the rotary joint under severe operating conditions.

[0005] From a manufacturing perspective, achieving a long-life dynamic seal requires extremely high geometric precision on the dynamic sealing surface of the rotating shaft. Traditional manufacturing methods involve precision machining each component independently, followed by assembly via press fitting or interference fit. However, even with high machining precision for each part, stress generated during assembly and unavoidable tolerance accumulation can still cause a slight deviation between the final assembly's rotational axis and the reference axis used during individual component machining. This residual geometric error results in minute radial runout of the dynamic sealing surface, leading to uneven stress on the sealing lip and accelerated wear, thus preventing it from reaching its theoretical design life. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a high-sealing rotary joint that can provide early warning of early failure of core dynamic seal, while having high reliability and long service life, and to provide a manufacturing process that can fundamentally eliminate assembly accumulation error and produce the high-precision rotary joint.

[0007] To solve the above-mentioned technical problems, the first aspect of the present invention provides a high-sealing rotary joint, which includes a rotary joint body I as a fixed outer shell, a rotary joint body II rotatably disposed inside the rotary joint body I, a thrust ball bearing for supporting the rotary joint body II, and two rotary seals disposed between the rotary joint body I and the rotary joint body II as dynamic seals.

[0008] The rotary joint body I is equipped with a leakage warning structure. This structure includes a fluid collection groove formed on the rotary joint body I, and a warning channel formed on the inner wall of the rotary joint body I, located between the rotary seal and the thrust ball bearing. When the internal rotary seal experiences a minor leak due to wear, the leaking fluid will first flow from the warning channel to the fluid collection groove, capturing and concentrating the leaking fluid to form a signal that can be perceived externally. This transforms an unpredictable, sudden leakage failure into a predictable and plannable maintenance event, avoiding the serious consequences of the leaking fluid directly contaminating the bearing.

[0009] In one specific embodiment, the outer end of the warning channel is connected to the liquid accumulation tank, and an observation window is installed at the opening of the liquid accumulation tank on the outer surface of the rotary joint body I. This arrangement allows the collected leaking fluid to flow to the observation window, providing the operator with a direct and clear visual warning signal.

[0010] Preferably, the rotary joint further includes a bidirectional labyrinth seal structure disposed on the outside of the thrust ball bearing. This non-contact seal structure, through centrifugal force and tortuous gap channels, prevents the intrusion of external contaminants and the loss of internal lubricant, thereby protecting the working environment of the thrust ball bearing and improving the reliability and lifespan of the device under harsh operating conditions.

[0011] Specifically, the bidirectional labyrinth seal structure includes multiple sets of protruding ribs integrally formed on the inner hole of the gland, and multiple sets of inner grooves integrally formed on the outer circumferential surface of the rotary joint body II. The protruding ribs and the inner grooves are staggered and non-contacting, forming a tortuous gap channel to achieve the above-mentioned bidirectional protection function.

[0012] A second aspect of this invention provides a manufacturing process for a high-sealing rotary joint, which aims to achieve ultra-high fitting accuracy by eliminating geometric errors caused by accumulated assembly tolerances and mating stresses. The process includes the following steps:

[0013] First, a rotary joint body II is pre-machined, which includes reserving a finishing allowance in the dynamic sealing surface area where the rotary joint body II mates with the rotary step seal.

[0014] Subsequently, the rotary joint body II and a thrust ball bearing are combined to form a rotating component assembly, and the rotating component assembly is subjected to deep cryogenic treatment; at the same time, a rotary joint body I is used as a fixed component assembly, and the fixed component assembly is subjected to preheating treatment.

[0015] Next, the rotary component assembly, which has undergone cryogenic treatment, is stress-free inserted into the preheated fixed component assembly and subjected to room temperature thermal equilibrium to form a precise interference fit.

[0016] The assembly that has achieved thermal equilibrium undergoes in-situ final machining under dynamic reference. This machining is performed with the rotary joint body I as a static reference. Based on real-time monitoring of the machining status, the rotary joint body II is driven to rotate using the thrust ball bearing already installed inside the assembly. A closed-loop control algorithm is used to adjust the machining parameters to remove the reserved finishing allowance. This method fundamentally ensures the coaxiality, roundness, and cylindricity of the dynamic sealing surface relative to the actual rotation axis, resulting in an ideal sealing mating surface.

[0017] Preferably, the pre-processing step of the rotary joint body II further includes surface strengthening treatment of the dynamic sealing surface area to improve its hardness and wear resistance, thereby extending the service life of the rotary seal and mating surface.

[0018] In one specific embodiment, the temperatures and holding times for the cryogenic treatment and preheating treatment are no longer fixed empirical values, but are determined by calculation using a heat transfer model based on the digital model of the components, and the assembly steps are performed in an inert gas environment. Model-based parameter optimization ensures the formation of the required gaps for stress-free assembly, while the inert gas environment avoids the impact of frost formation on the surface of the cryogenic components on the fitting accuracy.

[0019] Preferably, before the in-situ final machining step under the dynamic reference begins, a disposable temporary isolation seal is installed on the outside of the thrust ball bearing. This step ensures that the thrust ball bearing is not subject to secondary contamination by isolating grinding fluid and particles during machining, which is crucial for ensuring process feasibility.

[0020] In one specific embodiment, during the in-situ final machining step under the dynamic reference, the closed-loop control algorithm adaptively adjusts the depth of cut or workpiece rotation speed based on signals from acoustic emission or vibration sensors. All finishing allowances are removed through micro-grinding until the surface roughness of the dynamic sealing surface reaches Ra0.1μm or better. This ensures that the final dynamic sealing surface has extremely high surface finish, creating ideal hardware conditions for achieving a long-life, high-reliability dynamic seal.

[0021] This invention provides a high-sealing rotary joint and its manufacturing process. It has the following beneficial effects:

[0022] 1. This invention, by setting up a leakage early warning structure, transforms unpredictable sudden sealing failures into predictable and plannable maintenance events. When the core rotating seal experiences initial wear and generates a small leak, the leaking fluid is captured by the early warning channel and collects in the accumulator. This forms a clear, externally observable signal through the observation window, preventing damage caused by direct contamination of the thrust ball bearing by the leaking fluid, and greatly improving the safety and maintenance efficiency of the equipment.

[0023] 2. This invention adds a bidirectional labyrinth seal structure, which can actively utilize the centrifugal force field and the throttling effect of the tortuous channel to bidirectionally block the intrusion of external dust, water vapor and other pollutants as well as the loss of internal lubricant, providing a clean and stable working environment for the thrust ball bearing, thereby effectively extending its service life.

[0024] 3. The manufacturing process of this invention introduces in-situ final machining under dynamic reference. After the rotary joint completes the assembly, its own thrust ball bearing is used as the dynamic reference to drive the rotary joint body II to rotate, and its dynamic sealing surface is subjected to final micro-machining. This eliminates the final geometric error caused by the accumulation of component tolerances and the release of assembly stress, creating near-ideal fitting conditions for the rotary seal, thereby significantly improving the performance of the dynamic seal, reducing the wear rate, and extending its effective service life.

[0025] 4. This invention pre-compensates for heat treatment deformation and optimizes process parameters for low-temperature assembly through simulation calculations based on digital models, thereby improving process accuracy and efficiency from the source. In the in-situ final processing step, sensor-based adaptive closed-loop control is introduced, transforming the processing from traditional experience-based to data-driven, ensuring the stability and consistency of the final geometric accuracy of each product while improving production efficiency. Finally, the establishment of a full-process digital history for each product enables quality traceability, providing a solid data foundation for continuous process improvement and quality management. Attached Figure Description

[0026] Figure 1This is a perspective view of the present invention;

[0027] Figure 2 This is an exploded view of the rotary joint structure of the present invention;

[0028] Figure 3 This is a cross-sectional view of the internal structure of the rotary joint of the present invention;

[0029] Figure 4 for Figure 3 Enlarged view of A in the middle;

[0030] Figure 5 for Figure 3 Enlarged view of B in the middle;

[0031] Figure 6 This is a schematic diagram of the preparation process of the present invention.

[0032] Among them, 1. Thrust ball bearing; 2. O-ring; 3. Rotary seal; 4. Rotary joint body I; 5. Rotary joint body II; 6. Pressure cap; 7. Retaining ring; 8. Observation window; 9. Rib; 10. Inner groove; 11. Warning channel; 12. Liquid accumulation tank. Detailed Implementation

[0033] The technical solutions in 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.

[0034] To better understand the present invention, the above content will be described in detail below with reference to specific embodiments.

[0035] Please see the appendix Figure 1 - Appendix Figure 5 The present invention provides a high-sealing rotary joint, which includes a rotary joint body I4 serving as a fixed base, and a rotary joint body II5 rotatably passing through the inner cavity of the rotary joint body I4 in a coaxial manner. The rotary joint body II5 is used to transport fluid media.

[0036] In this embodiment, the thrust ball bearing 1 is disposed inside the rotary joint body I4. The outer ring of the thrust ball bearing 1 mates with the inner wall of the rotary joint body I4, while its inner ring is mounted on the outer surface of the rotary joint body II5. The thrust ball bearing 1 is used to bear the axial load generated by the rotary joint body II5 during operation and to provide radial support for its smooth rotation.

[0037] The retaining ring 7 is installed in an annular groove on the outer surface of the rotary joint body II 5. One end face of the retaining ring 7 abuts against the end face of the inner ring of the thrust ball bearing 1, thereby achieving axial positioning of the thrust ball bearing 1 and ensuring that the axial position of the rotary joint body II 5 within the rotary joint body I 4 remains stable.

[0038] At one end opening of the rotary joint body I4, a pressure cap 6 is detachably fixed by multiple bolts. The central through hole of the pressure cap 6 allows the rotary joint body II5 to pass through, and it serves to seal and protect the internal components of the device.

[0039] An O-ring 2 is provided between the inner ring of the gland 6 and the mating surface of the rotary joint body II 5. The O-ring 2 is compressed and filled in the gap between the two to achieve a dynamic seal between the gland 6 and the rotary joint body II 5, preventing external contaminants from entering the device or internal media from leaking from the static mating surface.

[0040] Two annular mounting grooves are axially spaced on the inner wall of the rotary joint body I4, located inside the thrust ball bearing 1. Two rotary step seals 3 are respectively installed in these two annular mounting grooves. The sealing lip of each rotary step seal 3 maintains dynamic contact with the outer circular surface of the rotary joint body II5, forming two core dynamic sealing barriers to prevent the internal fluid medium from leaking outward along the gap between the rotary joint body I4 and the rotary joint body II5 under high pressure differential and relative rotation conditions. An O-ring 2 is provided between the rotary step seal 3 and the groove of the rotary joint body I4, which continuously and stably pushes open the sealing lip from behind, allowing it to fit tightly against the surface of the rotary joint body II5.

[0041] In this embodiment, the rotary joint is equipped with a leakage early warning structure to enable visual monitoring of the core dynamic sealing working status.

[0042] An annular fluid collection groove 12 is formed on the inner wall of the rotary joint body I4, between the rotary step seal 3 and the thrust ball bearing 1, located axially on the inner side. During the normal service life of the rotary step seal 3, this fluid collection groove 12 remains dry. When the rotary step seal 3 experiences initial failure due to long-term wear, a small amount of leaking fluid will breach the seal. At this time, the function of the fluid collection groove 12 is to capture and collect this leaking fluid immediately, thereby confining the leak to a specific area and preventing it from directly intruding into and contaminating the adjacent thrust ball bearing 1.

[0043] A warning channel 11 is machined on the shell wall of the rotary joint body I4. The outer end of the warning channel 11 is connected to the liquid accumulation tank 12, forming a fluid passage from the internal warning channel 11 to the external liquid accumulation tank 12.

[0044] An observation window 8 is sealed and installed at the opening of the sump 12 on the outer surface of the rotary joint body I4. Leaking fluid flows from the warning channel 11 into the sump 12. When the leaking fluid reaches a certain level, it accumulates along the sump 12 and flows to the observation window 8. The operator can visually observe the fluid behind the observation window 8 to receive a clear warning signal that the internal seal has begun to fail. This structure transforms unpredictable, sudden leaks into predictable, plannable maintenance events, significantly improving equipment operational safety and maintenance efficiency.

[0045] This embodiment also provides a non-contact, bidirectional labyrinth seal structure on the outside of the thrust ball bearing 1 to provide physical isolation to the lubrication chamber where the thrust ball bearing 1 is located.

[0046] This bidirectional labyrinth seal structure is formed by the specific geometric features of the stationary and rotating components. Multiple sets of annular ribs 9 are integrally formed on the inner wall of the gland 6. Correspondingly, multiple sets of annular grooves 10 are integrally formed on the outer surface of the rotary joint body II 5. After assembly, the ribs 9 and grooves 10 intersect without physical contact, together forming a complex and tortuous radial clearance channel.

[0047] When the rotary joint body II5 rotates at high speed, the centrifugal force field it generates will throw off dust, water vapor and other pollutants from the external environment that are trying to penetrate radially. At the same time, any airflow or liquid that attempts to penetrate axially will undergo multiple throttling and expansion when passing through the tortuous channel, resulting in the dissipation of its energy and a reduction in its flow velocity. The solid particles it carries will be deposited in the channel due to inertial collisions, thus preventing them from reaching and contaminating the internal thrust ball bearing 1.

[0048] The tendency of grease to overflow in the thrust ball bearing 1 under high temperature or centrifugal force is also blocked by this labyrinth seal structure. The ejected grease particles are captured by the inner wall of the channel and guided back into the bearing cavity under centrifugal force, thus effectively preventing lubricant loss and ensuring long-term stable lubrication of the thrust ball bearing.

[0049] Working principle: In operation, rotary joint body II5 rotates inside rotary joint body I4, which serves as a fixed outer shell. Thrust ball bearing 1 is located inside rotary joint body I4, providing support for the rotation of rotary joint body II5. Retaining ring 7, mounted on rotary joint body II5, contacts thrust ball bearing 1, axially positioning thrust ball bearing 1. Pressure cap 6 is fixedly connected to the end of rotary joint body I4 by multiple bolts.

[0050] Two rotary step seals 3 serve as dynamic seals, installed in internal grooves within rotary joint body I 4 and contacting the outer circumferential surface of rotary joint body II 5 to isolate the internal fluid medium. Multiple O-rings 2 serve as static seals and pressure actuations, respectively positioned on the inner ring of the gland 6 and the outer sides of the two rotary step seals 3, to ensure sealing between the fixed connection surfaces and to continuously provide pressure to the sealing lips of the rotary step seals 3 on the outer circumferential surface of rotary joint body II 5.

[0051] A sump 12 is formed on the rotary joint body I4, located between the rotary seal 3 and the thrust ball bearing 1. A warning channel 11 is formed on the rotary joint body I4, with its outer end connected to the sump 12. When fluid leaks from the rotary seal 3, it first enters the warning channel 11, then flows through the warning channel 11 to the sump 12, and finally flows to the observation window 8 installed on the outside of the rotary joint body I4.

[0052] In addition, a two-way labyrinth seal structure is provided on the outside of the thrust ball bearing 1. This structure consists of multiple sets of raised ribs 9 integrally formed on the inner hole of the gland 6 and multiple sets of inner grooves 10 integrally formed on the outer circular surface of the rotary joint body II 5. The raised ribs 9 and the inner grooves 10 are staggered and non-contacting, forming a tortuous gap when the rotary joint body II 5 rotates.

[0053] Reference Appendix Figure 6 Another embodiment of the present invention provides a process for manufacturing a high-sealing rotary joint, which includes the following steps:

[0054] Pre-processing and preparation steps for rotary joint II and various key metal components.

[0055] Pre-processing and preparation steps based on digital twins:

[0056] For the machining of rotary joint body I (4), gland (6) and rotary joint body II (5), a precise digital twin model of each key component is first created in the Manufacturing Execution System (MES).

[0057] Intelligent computing and simulation optimization:

[0058] Before semi-finishing, heat treatment simulation is performed on the digital twin model using finite element analysis (FEA) software. The calculations predict and quantify the minute deformations that may be caused by tempering or solution treatment. The results are then used to pre-compensate the dimensions of the semi-finished drawing at the μ-level, ensuring that the heat-treated part is closer to the ideal dimensions and reducing the allowance and difficulty of subsequent finishing grinding.

[0059] For the surface strengthening treatment of rotary joint body II (5), historical process data is analyzed using machine learning algorithms to establish a predictive model between the surface hardening layer depth, hardness distribution, and quenching process parameters (such as power and scanning speed). Before processing, MES automatically recommends or generates the optimal combination of process parameters based on this predictive model to obtain the most ideal wear resistance performance.

[0060] Based on material batches, heat treatment simulation results, and historical processing data, the system uses an optimization algorithm to accurately calculate the required finishing allowance for the dynamic sealing surface, optimizing it from a fixed range (e.g., 3-5 μm) to an optimal specific value for the current workpiece, in order to minimize the time required for subsequent in-situ machining.

[0061] For the rotary joint body I4 and the pressure cap 6, which serve as the fixed outer shell, the materials used are alloy structural steel with excellent comprehensive mechanical properties, such as 42CrMo, or austenitic stainless steel with good corrosion resistance, such as 316L.

[0062] The bar stock or forging is turned and milled using a CNC machining center to complete the semi-finishing of its main body shape, inner hole, bolt hole, as well as the liquid accumulation tank 12 and the warning channel 11 in the leakage warning structure;

[0063] For the gland 6, the outline of the annular rib 9 required for the bidirectional labyrinth seal structure is integrally machined into its inner hole. After machining, the parts are subjected to appropriate heat treatment, such as quenching and tempering for parts made of 42CrMo material, or solution treatment for parts made of 316L material, to stabilize the material structure and eliminate machining stress.

[0064] After heat treatment, each mating surface is precision ground using a high-precision internal and external cylindrical grinding machine to achieve a dimensional tolerance of IT6 and a surface roughness of no less than Ra0.4μm.

[0065] For the rotary joint body II5, which serves as the rotating spindle, the material selected is bearing steel or hard alloy steel with high hardness and high wear resistance, such as GCr15 or 20CrMnTi.

[0066] The bar stock is machined using a CNC lathe to complete the outline of the main body, the central fluid channel, the mounting groove of the retaining ring 7, and the annular inner groove 10 required for the bidirectional labyrinth seal structure;

[0067] Subsequently, the outer circular surface of the rotary joint body II5, especially the dynamic sealing surface area that mates with the rotary step seal 3, undergoes surface strengthening treatment. This surface strengthening treatment can be high-frequency quenching or carburizing quenching, to achieve a surface hardness of 58-62 HRC, thereby obtaining excellent wear resistance.

[0068] After heat treatment, the rotary joint body II5 is precision ground. Except for the dynamic sealing surface, the dimensional tolerances of the remaining mating surfaces reach IT6 level.

[0069] During the precision grinding of the rotary joint body II5, the dynamic sealing surface area that mates with the rotary step seal 3 is not machined to the final design dimensions in one go, but a finishing allowance of 3-5 μm is intentionally reserved. The surface roughness of this area is controlled at Ra0.2-0.4 μm at this time. This reserved micro-machining allowance is a necessary preparation for subsequent in-situ final machining in the assembled state of the device. Based on material batches, heat treatment simulation results, and historical machining data, the system uses an optimization algorithm to accurately calculate the required finishing allowance for the dynamic sealing surface, optimizing it from a fixed range (such as 3-5 μm) to an optimal specific value for the current workpiece, in order to minimize the time required for subsequent in-situ machining.

[0070] After the pre-processing and preparation of each component are completed, the low-temperature stress-free assembly step begins.

[0071] This step utilizes the physical properties of thermal expansion and contraction of materials to achieve precise fitting of core components without the application of external mechanical force.

[0072] Before cryogenic and preheating treatments, the system calls upon the digital twin models of the components and their material thermophysical properties to perform rapid simulation calculations using a heat transfer model. The purpose of this calculation is to accurately determine the minimum cryogenic temperature and shortest holding time required for rotating component assemblies, as well as the optimal preheating temperature and holding time required for stationary component assemblies, based on the current ambient temperature and humidity. This replaces the practice of relying on fixed empirical ranges (such as 100-120℃), achieving personalized and optimized temperature control for each batch and each workpiece, ensuring a stable temporary clearance required for assembly while minimizing energy consumption and maximizing efficiency.

[0073] The rotary joint body II5 with the retaining ring 7 already installed is combined with the thrust ball bearing 1 to form a rotating component assembly. This rotating component assembly is placed in a liquid nitrogen cryogenic treatment chamber and cryogenically treated at a temperature of -196°C for 30 to 60 minutes to ensure that the assembly achieves sufficient and uniform dimensional shrinkage.

[0074] Meanwhile, the rotary joint body I4, with the rotary step seal 3 already installed, is placed in a precision constant temperature forced-air drying oven as a fixed component assembly. The fixed component assembly is heated at a temperature of 100-120℃ for 30-60 minutes to allow its inner hole to undergo controllable and uniform thermal expansion.

[0075] Assembly operations are carried out in an environment filled with a dry, inert gas, such as an assembly workstation or glove box purged with nitrogen. The purpose of this inert gas environment is to prevent moisture in the air from condensing into frost on the surfaces of cryogenically treated parts, thereby ensuring the cleanliness of the assembly process and the final fit accuracy.

[0076] Using a specialized vertical assembly guide fixture, the cryogenically treated rotating component assembly is quickly removed from the processing chamber and smoothly slid into the preheated fixed component assembly's inner bore using a purely axial sliding motion. Due to the temporary gap created by the temperature difference, no mechanical pressure is required throughout the assembly process.

[0077] After the sliding assembly is completed, the preliminarily assembled device assembly is moved to an environment with a room temperature of 20±5℃ and allowed to stand naturally for 2 to 4 hours. During this period, the previously chilled components will absorb heat and expand, while the previously preheated components will dissipate heat and shrink. Ultimately, the required interference fit will be formed between the outer ring of the thrust ball bearing 1 and the inner hole of the rotary joint body I4, and between the inner ring of the thrust ball bearing 1 and the outer ring of the rotary joint body II5.

[0078] The fit formed by this method has an extremely uniform internal stress distribution, avoiding local stress concentration and shell deformation caused by traditional press-fitting processes.

[0079] Once the assembly has achieved thermal equilibrium, it enters the in-situ final machining step under dynamic reference. This step aims to eliminate geometric errors caused by accumulated assembly tolerances and fitting stress.

[0080] Before machining begins, a disposable temporary isolation seal is installed on the outside of the thrust ball bearing 1 and on the inside of the dynamic sealing surface area to be machined in the assembled device assembly. This seal can be a custom-made lip seal ring made of flexible graphite composite material or high-temperature silicone rubber. Its function is to strictly prevent grinding fluid and grinding particles from entering the chamber where the thrust ball bearing 1 is located during subsequent machining, ensuring the cleanliness of the bearing.

[0081] In addition, high-frequency acoustic emission (AE) sensors and vibration sensors are installed on the fixed fixture near the grinding area on the ultra-precision grinding machine.

[0082] Subsequently, the assembly with the temporary seal installed is moved to an ultra-precision cylindrical grinder or a single-point diamond lathe. A non-deformable high-precision hydraulic chuck is used to clamp the outer cylindrical surface of rotary joint body I4, fixing it as the static reference for the entire system. A flexible coupling connects and drives the end of rotary joint body II5, allowing it to rotate at 100-300 RPM, entirely relying on the thrust ball bearing 1 already installed inside the assembly. This clamping and driving method ensures that the rotation axis of rotary joint body II5 is the actual dynamic rotation center of the assembly during actual operation.

[0083] At the start of machining, the AE sensor precisely detects the instant of contact between the grinding wheel and the workpiece surface, achieving micron-level automatic calibration of the machining start point. This replaces traditional manual trial cuts or electrical contact measurements, resulting in higher efficiency and accuracy. During micro-grinding, an adaptive control algorithm runs in real time. This algorithm integrates signal data from the AE sensor and vibration sensor to continuously monitor the grinding status. If the algorithm identifies abnormal vibration signals caused by a dull grinding wheel or excessive grinding force, it automatically fine-tunes the depth of cut or workpiece rotation speed to suppress machining chatter and ensure surface quality. If the algorithm determines from the AE signal that grinding efficiency has decreased, it can automatically trigger an online dressing cycle of the grinding wheel to always keep the grinding wheel in optimal cutting condition.

[0084] The entire processing is dominated by this closed-loop adaptive control system, which automatically removes the reserved allowance until the surface roughness online measuring instrument (if equipped) reports that the target value of Ra0.1μm has been achieved.

[0085] This machining process completely removes the 3-5μm machining allowance retained in the pre-machining stage until the dynamic sealing surface reaches the final design dimensions. The resulting dynamic sealing surface achieves extremely high geometric accuracy in roundness, cylindricity, and coaxiality relative to the actual rotation axis of the assembly. Its final surface roughness can reach Ra0.1μm or better, providing an ideal mating surface for the rotary step seal 3.

[0086] After the in-situ final processing is completed, the post-processing and final assembly steps begin.

[0087] First, the disposable temporary isolation seals, which have fulfilled their isolation function, are carefully removed from the assembly and discarded. Then, the entire assembly undergoes a multi-step precision cleaning process to thoroughly remove all grinding particles and residual grinding fluid generated during the machining process.

[0088] The cleaning process includes: initial immersion cleaning of the assembly in petroleum ether to dissolve and remove oily contaminants. Next, it is transferred to an ultrapure aqueous solution containing 0.1-0.5 vol% of a nonionic surfactant, such as Triton X-100, for multi-stage ultrasonic cleaning, each stage lasting 15-30 minutes, to strip and suspend all solid particles through cavitation. Then, the assembly is finally rinsed with isopropanol to replace residual moisture and further clean it. Finally, all internal and external surfaces of the assembly are purged and dried in a clean environment using high-purity nitrogen gas with a purity of not less than 99.999%.

[0089] Perform the final assembly on a clean workbench. Correctly insert the O-ring 2 into the sealing groove of the gland 6. Then install the gland 6 onto the rotary joint body I4, and use a torque wrench to tighten the fixing bolts in 2 to 3 steps in a diagonal sequence until the final torque reaches the preset value of 15 to 20 N·m to ensure that the gland is installed flat and to avoid uneven stress.

[0090] Finally, the observation window 8 is sealed to the opening of the warning channel 11 on the outer wall of the rotary joint body I4 by means of thread or press-fit. This completes the entire manufacturing process of the high-sealing rotary joint. A thin layer of vapor phase rust inhibitor can be applied to the surface of the finished product for subsequent storage and transportation.

[0091] During final assembly, a digital torque wrench is used to tighten the fixing bolts. Each tightening torque, rotation angle, and timestamp is automatically recorded and linked to the product's unique serial number. From the initial material batch number and simulation data to temperature control parameters, in-situ machining sensor data streams, and finally the assembly torque, all information is integrated into the MES system, creating a complete and traceable "digital history" or "digital trail" for the rotary joint. This provides a solid data foundation for future quality analysis, continuous process improvement, and remote diagnostics.

Claims

1. A high containment rotary joint, characterized by, It comprises: The rotating joint body I (4) is sleeved outside the rotating joint body II (5), and the end of the rotating joint body I (4) is fixedly connected with a gland (6) through a plurality of bolts; two rotating stellite seals (3) are arranged between the internal clamping groove of the rotating joint body I (4) and the outer surface of the rotating joint body II (5); O-rings (2) are arranged outside the two rotating stellite seals (3); A thrust ball bearing (1) is arranged inside the rotating joint body I (4) and used for supporting the rotating joint body II (5); a retainer ring (7) is mounted outside the rotating joint body II (5) and used for axially positioning the thrust ball bearing (1); A leakage warning structure is arranged on the rotating joint body I (4), the leakage warning structure comprises a warning channel (11) formed in the rotating joint body I (4), and a liquid accumulation groove (12) for collecting leaked fluid is formed between the rotating stellite seal (3) and the thrust ball bearing (1) and outside the rotating joint body I (4).

2. A high containment rotary joint according to claim 1, wherein, The outer end of the warning channel (11) is in communication with the liquid accumulation groove (12), and an observation window (8) is mounted at the outer opening of the liquid accumulation groove (12).

3. A high containment rotary joint according to claim 1, wherein, A bidirectional labyrinth seal structure is further arranged outside the thrust ball bearing (1).

4. A high containment rotary joint according to claim 3, wherein, The bidirectional labyrinth seal structure comprises a plurality of convex ribs (9) integrally formed on the inner hole of the gland (6) and a plurality of inner grooves (10) integrally formed on the outer circular surface of the rotating joint body II (5), and the convex ribs (9) and the inner grooves (10) are staggered and non-contact.

5. A high containment rotary joint according to claim 1, wherein, An O-ring (2) is further arranged between the inner ring of the gland (6) and the rotating joint body II (5).

6. A process for the production of a high containment rotary joint for the production of a high containment rotary joint according to any one of claims 1 to 5, characterized in that, The method comprises the following steps: Preprocessing is performed on the rotating joint body II (5) and each key metal part, and the preprocessing comprises reserving a finish machining allowance in a dynamic sealing surface area of the rotating joint body II (5) and the rotating stellite seal (3); The rotating joint body II (5) and the thrust ball bearing (1) form a rotating component assembly, the rotating component assembly is subjected to cryogenic treatment, the rotating joint body I (4) is taken as a fixed component assembly, and the fixed component assembly is subjected to preheating treatment; The rotating component assembly subjected to the cryogenic treatment is arranged in the fixed component assembly subjected to the preheating treatment to form a device assembly, and the device assembly is subjected to thermal balance; The device assembly subjected to the thermal balance is subjected to in-situ final machining under a dynamic reference, the rotating joint body I (4) is taken as a static reference, the rotating joint body II (5) is driven to rotate by the thrust ball bearing (1) in the assembly, and a machining parameter is adjusted by a closed-loop control algorithm to remove the finish machining allowance reserved in the dynamic sealing surface area on the basis of real-time monitoring of a machining state.

7. A process for manufacturing a high containment rotary joint according to claim 6, characterized in that, The preprocessing of the rotating joint body II (5) further comprises surface strengthening treatment in the dynamic sealing surface area.

8. A process for manufacturing a high containment rotary joint according to claim 6, characterized in that, The temperature and holding time of the deep cryogenic treatment and preheating treatment are determined based on a digital model of the parts by a heat transfer model, and the step of loading the rotating component assembly into the fixed component assembly is performed in an inert gas environment.

9. A process for manufacturing a high containment rotary joint according to claim 6, characterized in that, Before the in-situ finish machining under the dynamic reference, a disposable temporary isolation seal is installed on the outside of the thrust ball bearing (1) to block the grinding fluid during the machining process.

10. A process for manufacturing a high containment rotary joint according to claim 6, characterized in that, The closed-loop control algorithm adaptively adjusts the depth of cut or the workpiece rotation speed based on the signals of acoustic emission or vibration sensors, removes all the finishing allowance through micro-grinding, and ensures that the surface roughness of the dynamic sealing surface reaches Ra 0.1 μm or better.

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