1. Fatigue Challenges for "High-Frequency Short-Time" Synthesis (Fine Powder/RVD) For the synthesis of sawing-grade diamond fine powder, ultra-fine powder, and RVD single crystals, the process requires extremely short synthesis times. High-Frequency Impact: The synthesis time for these materials is only 1/5 of that for medium-coarse grit, meaning the equipment usage frequency is 5 times higher within the same working period. Structural Fracture Risk: This high-frequency alternating stress makes the hinge beams (especially the beam ears) highly prone to fatigue fracture.Design Shortcomings: Current design methods mostly rely on basic finite element optimization and lack deep simulation for frequency, fatigue, and non-linear analysis (such as using Solidworks Simulation), making it difficult to accurately predict and solve structural hazards under high-frequency conditions.2. Pressure Holding Challenges for "Long-Time" Synthesis (Large Single Crystals) When synthesizing gem-grade or industrial-grade large single crystals larger than 3mm, the process requires the equipment to maintain stable high pressure for a long time,.Stroke Limitations: Traditional cubic presses mainly rely on a single-pressure source supercharger to maintain pressure. However, the plunger stroke of existing superchargers is limited and cannot meet the ultra-long pressure holding requirements. Equipment Bottleneck: This forces existing equipment to be modified, such as replacing the traditional supercharger with ultra-high pressure oil pumps without stroke limits or reciprocating intensifiers; otherwise, the conditions for large single crystal synthesis cannot be met.3. Temperature Control Challenges for "Phase-Change Sensitive" Materials (Composite Sheets) Unlike sawing-grade diamonds which are relatively stable during synthesis, materials like diamond composite sheets undergo significant physical state changes.Non-Linear Changes: The material in the cavity transforms from solid to melt (phase change), causing volume changes, which in turn alter resistance and heat generation, ultimately leading to unstable cavity temperatures,.Control Lag: Traditional electrical control systems often struggle to rapidly capture these subtle and fast fluctuations caused by phase changes. Existing technology lacks sufficient intelligent compensation capabilities to ensure the consistency and stability of the synthesized samples.4. Cavity Challenges for "Extreme High Pressure" Needs As the demand for higher-grade materials increases, the traditional cubic press faces physical bottlenecks in pressure upper limits and cavity expansion.Anvil Limits: The diameter of tungsten carbide anvils cannot be infinitely enlarged, limiting the size of the synthesis cavity and the upper pressure limit.Structural Limitations: Compared to two-die (belt press) technology, the cubic press has limitations in generating ideal pressure and temperature fields. It requires transplanting the multi-layer annular mold structure of two-die presses or developing special 6-8 anvil devices to break through this technical ceiling.
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1. Raw Material and Equipment Preparation Equipment: A domestic CS–XIII type hinge-style cubic press is used for synthesis.Materials: Specially proportioned diamond micropowder and cemented carbide (as the substrate) are selected.2. High-Temperature High-Pressure (HPHT) Sintering This is the critical step for forming the polycrystalline diamond composite structure.Process Conditions: The assembled raw materials are placed in the press and sintered at temperatures of 1300–1600°C and pressures of 5.5–7.5 GPa. This process creates the initial composite blank, combining the diamond powder with the carbide to achieve high hardness and toughness.3. Subsequent Shaping and Processing The sintered blank must undergo precision machining to form the final non-planar structure.Procedures: These include sandblasting, cylindrical grinding, and lapping.Forming: Through these steps, the blank is shaped into specific non-planar geometries, such as ridge (dual-edge), 3-ridge, 4-ridge, and 5-ridge structures.4. Cutting Edge Angle Design and Control Controlling the geometric angle of the cutting edge is a crucial process parameter for optimizing performance.Basic Design: Initially, the angle between the cutting edge and the vertical direction is set to 90°. Optimization: To further enhance fatigue impact resistance, the process involves adjusting this angle to be greater than 90° (e.g., 99°). Experiments prove that this modification significantly boosts impact resistance while maintaining wear resistance and load performance.
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The hinge beam, as the core load-bearing component of the cubic press, faces severe fatigue fracture risks under specific working conditions. The following is a detailed analysis of the factors affecting its fatigue strength and design improvements:1. Core Factors Affecting Fatigue StrengthThe literature points out that hinge beam fatigue is highly condition-specific, mainly occurring during the synthesis of sawing-grade fine grits, ultra-fine grits, and specific type-I single crystals.Extremely High Usage Frequency (Alternating Loads): This is the most direct cause of fatigue failure. When synthesizing fine, ultra-fine, or type-I single crystals, the single synthesis time is extremely short, only 1/7 of the time required for medium-coarse grits. This means that within the same working period, the number of synthesis cycles (pressurization-holding-depressurization) for this equipment is about 5 times that of medium-coarse grit synthesis.Cumulative Fatigue Effect: This high-frequency reciprocating operation subjects the hinge beam to massive alternating load cycles in a short period, easily leading to ear tearing or even beam body fracture, phenomena not fully considered in traditional designs for low-frequency operations (like medium-coarse grit synthesis).Limitations of Traditional Design Philosophy: Existing hinge beam designs are mostly derived from finite element optimization focusing on static strength analysis, often neglecting the impact of fatigue strength. Such designs fall short when facing the special product synthesis involving high-frequency operations.2. Direction and Strategy for Improved DesignTo solve these problems and improve the stability and lifespan of equipment producing fine-grain diamond, the literature proposes the following improvement directions:Introduction of More Applicable Strength Theories: For equipment dedicated to producing fine grits, the design calculation of the hinge beam should abandon simple static analysis and adopt the third and fourth strength theories. This design basis is considered more reasonable and practical when dealing with complex stress and fatigue issues. Manufacturing Process Innovation: From Casting to Forging: Status Quo: Due to cost and forging technology limitations, early hinge beam designs in China mostly used casting forms. Improvement: With the improvement of forging technology, costs have significantly decreased. For high-frequency equipment, the forged hinge beam design concept should be adopted. The forging process significantly improves the density and fiber continuity of the metal material, thereby greatly enhancing fatigue strength. The literature notes that the earliest hinge-type cubic presses in the United States used forged beam structures.Promoting "Dedicated Equipment" Design Thinking: Future design trends should not be "one machine for multiple uses," but rather creating dedicated equipment tailored to the synthesis characteristics of different superhard materials. For the high-frequency characteristic of fine-grain diamond synthesis, the fatigue strength design of the hinge beam should be specifically reinforced, rather than simply using general-purpose models.
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The alloy infiltration method (specifically the iron-nickel-based alloy infiltration technique) plays a critical role in improving the compatibility between diamond and binder and enhancing tool life. This is reflected in the following aspects:1. Improving the Compatibility between Diamond and Binder Reducing Thermal Expansion Differences: The alloy infiltration method effectively reduces the thermal expansion difference between the diamond and the binder (metal solvent). This mismatch is a core issue in compatibility, as the large disparity in coefficients of thermal expansion is the primary cause of residual stress within the Polycrystalline Diamond Compact (PDC).Optimizing Proportion Control: Compared to the traditional powder-mixing method, the alloy infiltration method makes the metal solvent ratio easier to control and offers stronger maneuverability, thereby supplying an adequate proportion between the diamond and the binder.2. Reducing Residual Stress Minimizing Stress Generation: By effectively reducing the difference in thermal expansion coefficients and providing an appropriate binder proportion, this method plays a positive role in preparing PDC with low stress levels.Improving Stress Distribution: Samples prepared using this method exhibit residual compressive stresses that are uniformly distributed in both the axial and radial directions.3. Increasing Tool Life Addressing Short Life Issues: Practical applications indicate that oversize residual stress results in shorter life performance for PDC. The alloy infiltration method directly resolves this key factor limiting lifespan by synthesizing high-quality PDC with low residual stress. Enhancing Wear Resistance and Structural Quality: PDC synthesized via this method possesses a high-density diamond layer structure. X-ray diffraction confirms the presence of cubic diamond, alloy, and carbide phases without any detected graphite phase. This promotes the growth of diamond-to-diamond (D-D) bonds, resulting in high-quality, wear-resisting tool materials.The alloy infiltration method fundamentally reduces destructive residual stress through physical matching (reducing thermal expansion mismatch) and process optimization (precisely controlling binder proportions). This not only strengthens the material's microstructural bonding but also significantly extends the tool's service life.
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According to the provided literature, the core key to centering technology for a cubic press can be summarized in one phrase: Ensuring Torque Balance.To achieve this core goal, at the level of engineering manufacturing and practical application, one must rely on two pillars: extremely high Machining Accuracy (Static Foundation) and excellent Structural Rigidity (Dynamic Guarantee).1. Theoretical Key: Ensuring Torque Balance The literature explicitly states, "Ensuring torque balance is the key to cubic press centering technology". Eliminating Additional Force Couples: Ideal centering means there are no forces in the system that cause components to twist. If the piston centerline does not coincide with the hinge beam centerline (eccentricity), or if there is an angle, an "additional force couple" is generated. Consequences: This extra torque destroys the sealing space, causing the equipment to become a "typical blowout press," or causes twisting trends in the dies and hinges, severely shortening their lifespan,.2. Physical Implementation Key: Accuracy and Rigidity To achieve the aforementioned torque balance, two physical problems must be solved, which are the keys to ensuring good equipment centering:A. Machining Accuracy (Foundation for Static Centering) Machining accuracy directly determines whether the equipment is "innately" centered in an unpressurized state. Hinge Accuracy: The centerlines of the 12 hinge pins must form a perfect regular cube, and pinhole diameters and fit tolerances must be consistent. Poor accuracy leads to uneven force on hinges and causes beam fracture. Concentricity: The piston centerline must coincide with the hinge beam centerline and intersect at the Equipment Center. If an eccentricity exists, destructive additional force couples will arise. Cylinder Bore Consistency: If cylinder sizes vary, the stronger cylinder will push the chamber toward the weaker one, generating shear forces.B. Structural Rigidity (Guarantee for Dynamic Centering) The literature particularly emphasizes that structural rigidity is the guarantee for the equipment to possess good centering performance when working under high pressure. Definition of Rigidity: The equipment as a whole undergoes only equal amounts of elastic deformation. Dynamic Instability: Even if initial accuracy is high (static centering), if a specific beam or cylinder has poor rigidity, it will undergo excessive axial stretching or radial deformation under high pressure. If this deformation is inconsistent, it leads to "dynamic" misalignment under high pressure, triggering blowouts. Auto-Adjustment Capability: Good rigidity, combined with the floating characteristic of pistons in hydraulic oil, allows the system to perform minute automatic centering adjustments without breaking the seal.3. Ultimate Goal: Three Centers Unification The ultimate purpose of all centering technologies is to enable the Equipment Center to completely overlap with the Die Center and Material Center under ultra-high pressure (Three Centers Unification).The Equipment Center is determined by the machine's own accuracy and rigidity.The Die Center and Material Center can be compensated and adjusted through "anvil adjustment" and assembly structure design.Summary and Analogy The key to centering technology lies in maintaining perfect geometric symmetry and force balance even under extreme pressure.Analogy for Understanding: Imagine six people (six cylinders) standing in a circle, using their palms to jointly lift a heavy pyramid (the ultra-high pressure chamber).Machining Accuracy is like requiring these six people to have absolutely precise positioning, with palm heights exactly the same. If someone stands crookedly (eccentricity), the pyramid will tilt and slide.Structural Rigidity is like requiring these six people's arms to be as hard as steel. If someone is weak and their arm bends immediately upon lifting (large deformation), the pyramid will collapse toward that side (blowout).Torque Balance is the final result: regardless of the load, the pushing forces of the six people cancel out perfectly, and the pyramid remains motionless, neither rotating nor tipping over.
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The optimization of the main structure of the heavy-tonnage cubic diamond press primarily focused on improving the equipment’s centering, synchronization, and pressure-keeping performance. Based on the analysis of existing hinged cubic press structures, the following key optimization measures were implemented.I. Main Body Structural Design Optimization1. Adoption of the Pocket Bottom Structure: The hinge beams and working cylinders utilized the pocket bottom structure. Physical testing indicates that this structure possesses superior structural rigidity compared to the traditional flange support structure.2. Live-Bottom Working Cylinder Design: The working cylinder was designed as a live-bottom structure. This structural approach separates the cylinder barrel and the cylinder bottom, improving material utilization, reducing raw material consumption, and greatly enhancing the process performance related to forging, machining, and heat treatment.3. Working Cylinder Wall Thinning and Reduced Fit Clearance: While ensuring that mechanical processing requirements are met, the design sought to minimize the wall thickness of the working cylinder barrel and reduce the cooperation clearance between the barrel’s outer diameter and the hinge beam’s inner bore. This optimization improves the centering ability of the press. When the barrel is subjected to ultra-high hydraulic pressure, it undergoes slight elastic deformation and presses against the inner wall of the hinge beam, improving the stress conditions and extending the barrel’s service life.4. Shortening of Key Component Lengths: While maintaining component strength, the length of the working cylinder and hinge beam was shortened, thereby reducing steel consumption and manufacturing costs.5. Optimization of Hinge Beam Lug Shape: The shape of the hinge beam lugs was rationally designed. By keeping the extension surfaces of adjacent lugs parallel and ensuring that the traditional hinge beam lugs project appropriately higher than the outer diameter of the barrel, the strength of the dangerous bottom cross-section was effectively enhanced, and the rigidity of the equipment was increased.II. Piston and Connection Optimization1. Installation of Bronze Wear Strips on Pistons: To resolve the common "scoring" (cylinder scratching) problem during press use and enhance centering, bronze wear strips were installed on the pistons. This measure reduced the fit clearance between the piston and the working cylinder to 0.01 mm, which greatly improved the press's centering and completely solved the "scoring" issue, preventing subsequent synchronization problems or component scrapping.2. Rearward Shift of Piston Center of Gravity: To reduce the downward deflection of the six horizontal anvils when they advance, the design required the piston's center of gravity to be shifted backward to eliminate deflection caused by the weight of the piston in the horizontal direction.3. Use of Elastic Gap-Free Pin Connection: Elastic gap-free pin connections were used between the hinge beams. This novel pin design eliminates the clearance between the hinge beams, creating an interference fit, thereby significantly improving the equipment's centering, synchronization, and pressure-keeping performance. Eliminating clearance also helps enhance the coordination of the equipment's inherent deformation.
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The "digital" control system, composed of a Programmable Logic Controller (PLC), pressure sensors, and pressure gauges, primarily implements the following three functions on the HPHT Hydraulic Cubic Press apparatus:1、Realizing the logical control of electrical actions: This refers to controlling the sequence of actions of executive components (such as solenoid valves) in the electrical system, ensuring they are energized according to the press operation steps. Compared to traditional relay logical control, the PLC can realize the required functions in real-time by compiling a ladder diagram and is more flexible when needing to modify or add/delete the energization sequence of solenoid valves.2、Realizing pressure control and fault diagnosis: This includes the precise control of the hydraulic system and pressure parameters, as well as the rapid judgment of system anomalies. For example, the system can use the pressure gauge, a "digital" system, to adjust the throttle valve to obtain six-cylinder synchronous pressure. In terms of fault diagnosis, the system can retrieve operating statuses and abnormal phenomena via the touch screen (such as the state of the booster travel switch contacts or the phenomenon of taking too long to reach overpressure), thereby inferring the fault cause and locating the specific component.3、Realizing the execution and storage of process parameter curves: The digital system enables the press apparatus to operate according to preset process curves (such as the technology curve for synthesizing diamond with powder catalyst, shown in Figure 2). Operators can set various parameters via the touch screen, such as overpressure pressure, starting heating pressure, pause time, final pressure, and soaking time, and precisely correspond power or voltage to different time periods, thus transforming the original unknown and passive control method into an active control method. Simultaneously, the system can also store these process parameter curves.The PLC is the core technology that enables these functions. It possesses capabilities like logical operation, real-time counting, and sequential control, and also features A/D, D/A conversion, data operation, and data processing. These capabilities allow it to replace simple relay logical control systems that could only meet singular functional requirements.
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As the HPHT Hydraulic Cubic Press scales up, continuous improvements in its design and manufacturing process have resulted in significant structural advantages, particularly in the design and manufacturing of the main frame structure.1. Main Frame Structure Design and Optimization More Rational and Compact Structure: The design aims to reasonably reduce overall dimensions, which reduces equipment costs, makes the design more user-friendly, and ensures operability.Optimized Hinge Beam: The Finite Element Method (using software like ANSYs) is employed to optimize the hinge beam design, leading to a more rational force distribution and structure.Thin-Walled Work Cylinders: Thin-walled work cylinders are adopted to reduce the piston stroke while ensuring sufficient operating space.2. Fundamental Improvement in Work Cylinder Load-Bearing StructureIn traditional presses, the work cylinder was the main load-bearing component, leading to frequent "cylinder cracking". Modern designs have shifted the load-bearing mechanism from the original flange support to bottom support or double support.The core advantage of this modification is the transfer of the main load-bearing function from the work cylinder to the hinge beam. This change has successfully and completely solved the common problem of "cylinder cracking".A. "Double Support Structure" (Example: Guilin Metallurgical Machinery General Factory):1. Thin-Walled, Live-Bottom, Split-Type Work Cylinder: Reduces the work cylinder wall thickness from over 80mm to 30mm.2. Facilitates Scaling Up: Significantly reduces the overall dimensions of the main machine, which is favorable for large-scale development.3. Rational Force Distribution: The double-support structure allows the force to be rationally distributed between the bottom and the upper end face of the hinge beam.4. Improved Piston Durability: A wear-resistant band is designed on the piston to prevent scratching the work cylinder.B. "Bottom Support Structure" (Example: Designed by Lü Fengnong):1. Improved Overall Machine Concentricity: Achieves a gap-free fit between the work cylinder and the hinge beam, significantly improving the concentricity (centering accuracy) to within 0.1mm.2. Improved Stress Distribution: The specially shaped bottom of the work cylinder rationally improves the stress distribution of both the work cylinder and the hinge beam.3. Long-Term Stable Synchronicity: An anti-scratch ring is designed on the piston, ensuring that the synchronicity of the entire machine remains stable over the long term.
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CAN bus technology significantly enhances the functionality and performance of the HPHT Hydraulic Cubic Press control system by establishing an efficient and reliable communication network, demonstrating superiority, especially in meeting the higher demands for stability, precision, and real-time monitoring required by high-quality diamond synthesis processes.Here is a detailed explanation of how CAN bus technology enhances the functions and performance of the HPHT Hydraulic Cubic Press control system:I. Enhanced Functionality (Functionality Enhancement)CAN bus technology primarily achieves real-time coordinated control and centralized monitoring management by constructing two layers of networks: internal and external.1. Achieving Real-Time Data Exchange and Coordinated Control among Internal Control Units: Within a single hydraulic press, the CAN fieldbus connects control units equipped with CAN interfaces (such as the heating program setter, pressure controller, over/under current protector, recorder, etc.) to form an internal bus communication network. This network structure allows each control unit to both transmit data to and receive data from other control units. This completes the function of real-time data exchange and coordinated control during the working process. For example, the heating program setter controls the 15-segment heating curve, the pressure controller controls the pressure curve, and the recorder records and stores the parameters of every working cycle in real time.2. Achieving Workshop-Level Centralized Monitoring and Management: The recorder in the press control system serves as a node for that specific press control system. The control systems of various presses in the workshop, via these nodes and an industrial control computer (IPC), form an external communication network for data communication and control. This achieves the goal of centralized monitoring and management. A single upper computer in the central control room can perform data acquisition and monitoring for up to 50 presses on-site.3. Providing Remote Monitoring and Parameter Modification Capability: The external bus network transmits real-time pressure, current, set values for the process curve, and alarm information stored in the recorder module of the press control system to the upper computer for monitoring and storage. The upper computer can modify and control the parameters of any single press control system via the bus.II. Enhanced Performance and Superiority (Performance Enhancement and Superiority)CAN bus is recognized as one of the most promising fieldbuses, and its unique design and technical features bring significant performance improvements to the control system.1. High Reliability and Stability: CAN bus possesses excellent anti-interference characteristics and extremely high reliability. Actual operation has demonstrated that the system performance is stable and reliable. Practice over more than four years has proven the system has strong anti-interference capability.2. Accurate and Error-Free Data Transmission: CAN bus includes CRC check measures (Cyclic Redundancy Check) and features error identification and automatic retransmission functions. In actual application, connecting 50 presses at a baud rate set to 500 kbps, there was no data loss and no transmission errors between the upper computer and the lower machines.3. Technical Advantages Leading to Flexibility and Real-Time Performance: CAN bus technology offers advantages in flexibility, real-time capability, accuracy, and reliability. It adopts a multi-master working mode, enabling transmission methods like point-to-point, one-to-many, and global broadcast. It employs a non-destructive, priority-based competition bus arbitration method. Signal transmission uses a short frame structure (8 bytes per frame), with a maximum transmission rate of up to 1 Mbps.4. Positive Impact on Production Processes: The system provides a strong guarantee for the control of the synthesis process of the HPHT Hydraulic Cubic Press and the improvement of workshop management level. It also plays an obvious role in improving product quality grade and controlling costs.In essence, the CAN bus acts like the "nervous system" for the cluster of HPHT Hydraulic Cubic Presses. Inside a single press, it ensures real-time, error-free collaboration among subunits controlling critical parameters like temperature and pressure (internal network). At the entire workshop level, it allows the central control room to carry out unified command, remote adjustment, and status monitoring of all presses (external network), thereby transforming previously dispersed control into an integrated and highly efficient management system.
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The large-chamber synthesis process for the cubic press (such as 38mm and 40mm chambers), in contrast to traditional small-chamber processes (such as 28mm and 30mm chambers), faces challenges because the expansion of the chamber size alters the state of the pressure and temperature fields within the synthesis cavity. Optimizing the pressure and temperature control modes to fully exploit the advantages of large chambers has become the primary challenge for diamond factories.I. Pressure Field Challenges: Increased Pressure Gradient and Difficulty Maintaining Stable ConditionsThe growth of high-quality diamond single crystals requires relatively stable pressure conditions. However, the expansion of the chamber, combined with phase changes during the synthesis process, contributes to the challenge of generating a greater pressure gradient inside the synthesis cavity.1. Increased Pressure Gradient Due to Transmission Loss The enlargement of the synthesis chamber inevitably leads to an increase in the pressure difference (i.e., the pressure gradient increases) between the outer shell and the core of the synthesis rod, which is caused by pressure transmission loss.2. Volume Contraction and Pressure Drop from High Temperature and High Pressure Phase Changes The diamond growth process also causes changes in the pressure field. Under high temperature and high pressure, the transformation of graphite into diamond, using pyrophyllite as the pressure-transmitting medium, involves a series of phase changes:The pyrophyllite mineral phase change produces kyanite and coesite.The graphite phase change produces diamond. Because the specific gravity of these phase-change products is high, volume shrinkage occurs before and after the phase change, resulting in a drop in internal pressure within the synthesis chamber.3. Poorer Pressure Transmission Due to Increased Rigidity After the phase change, the friction coefficient and strength of the pyrophyllite increase, causing it to become rigid. This rigidity negatively affects the effectiveness of pressure transmission and pressure boosting. All these factors together lead to a greater pressure gradient inside the cavity.Core Challenge: The challenge for large-chamber processes is how to better reduce pressure loss and compensate for the pressure gradient.II. Temperature Field Challenges: Maintaining Uniformity and StabilityThe temperature field within the synthesis cavity is affected by two factors: heating and heat dissipation. Although the enlargement of the chamber objectively provides conditions for forming a more balanced and stable temperature field—meaning the spatial proportion that meets the required temperature conditions for the growth of high-quality diamonds will be greater in large chambers—practical control challenges persist.1. Generation of the Temperature Gradient The temperature field in the synthesis cavity is established through direct electric heating. The temperature gradient is generally considered to be generated by heat dissipation, and the temperature is expected to decrease gradually from the rod core outward.2. Difficulty in Maintaining Equilibrium In actual production, the phenomenon of asynchronous diamond growth between the rod core and the exterior often occurs, and the temperature gradient is cited as one of the causes. The critical challenge for temperature control is to realize or approach the balance point between heating and heat dissipation (i.e., a "heat preservation state") by adjusting the heating power appropriately and timely within the limited synthesis duration. Achieving this heat preservation state helps effectively reduce temperature changes and the temperature gradient.
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The HPHT Hydraulic Cubic Press is the "heart" equipment used for manufacturing synthetic diamonds. Since it operates for long periods under the extreme conditions of ultra-high temperature, high pressure, and frequent cyclic loads, its hydraulic system is prone to various issues, such as seal failure, oil contamination, and valve group jamming.Traditional diagnostic methods are often inefficient and rely heavily on human experience.To overcome this challenge, experts proposed using Artificial Intelligence (AI), specifically a technique called the Convolutional Neural Network (CNN), to act as the hydraulic system's "smart doctor."Here is a simplified explanation of how AI is utilized for fault diagnosis in the HPHT Hydraulic Cubic Press hydraulic system:Step 1: Collecting "Case Files" (Simulation and Data Acquisition)Training an AI doctor requires a vast amount of fault data, similar to how a human doctor studies numerous case reports.1. Identifying the "Illnesses": Researchers categorized the common faults in the HPHT Hydraulic Cubic Press hydraulic system into four major "illness types": hydraulic pump, hydraulic valve, hydraulic cylinder (cylinder body), and hydraulic pipeline faults. Specific examples of potential faults include hydraulic pump leakage, insufficient flow, valve core damage or jamming, cylinder seal failure, gas in the cylinder body, or pipe joint leakage.2. Creating a "Virtual Patient": Instead of damaging a real machine, experts built a highly realistic simulation platform of the hydraulic system using AMESim (or Automation Studio). The simulated cylinder diameter was 800 mm.3. Deliberately Introducing "Symptoms": On this virtual platform, researchers intentionally introduced various fault factors corresponding to the four types of faults (e.g., pump leakage, valve core damage, cylinder seal failure, pipe joint leakage).4. Collecting "Vital Signs": After a fault was introduced and the system stabilized, monitoring devices were placed at the oil inlets of six hydraulic cylinders to continuously collect two key operating indicators: pressure curves and velocity curves.5. Preparing the Dataset: To ensure the data was reliable and repeatable, each experimental condition was collected 10 times. Ultimately, 1,440 pressure and velocity curves were collected to form the AI training sample set. Different fault types have different characteristic impacts on these curves; for instance, pump leakage leads to a pressure drop, while gas in the cylinder causes velocity fluctuations.Step 2: Training the "Smart Doctor" (Convolutional Neural Network CNN)The CNN algorithm is a type of deep learning network known for its strong feature extraction capability and adaptability. It can automatically identify and extract key features from raw data.1. Data Input: The collected pressure and velocity curves (like the machine's "ECG" or "X-ray") were processed into training data suitable for the CNN, such as 25 pixels × 25 pixels grayscale images.2. Network Structure: The diagnostic model was designed based on the LeNet network and improved. The structure typically includes an input layer, convolutional layers, pooling layers, and fully connected layers. Convolutional Layer (The Core): This layer extracts local area features through multi-layer convolution operations. The ReLU activation function is used to enable the network to fit non-linear patterns. Pooling Layer: This follows the convolutional layer to reduce the feature map size and computation, retaining the most significant features. Max pooling is specifically used because it is beneficial for capturing extreme point feature information. Fully Connected Layer: This integrates the local features into global features. Output Layer: Using the Softmax function, the output maps to a probability distribution for the classification task, corresponding to the four hydraulic system fault types.3. Learning and Optimization: The AI model is trained by minimizing the Multi-class Cross-Entropy Loss Function. By adjusting network weights using gradient descent, the model continuously optimizes its diagnostic performance and reduces prediction errors.Step 3: Assessing the "Doctor's" Diagnostic Accuracy (Results Validation)The performance of the AI model was validated using a test set (split from the 1,440 samples, typically 8:2 for training/testing).• Single Input (Pressure): When only the pressure curve was input, the model's accuracy on the test set eventually converged to 1 (100%). The loss function approached 0 after 20 iterations.• Single Input (Velocity): When only the velocity curve was input, the model's accuracy on the test set also converged to 1 (100%). The loss function approached 0 after 32 iterations.• Combined Input (Pressure and Velocity): When pressure and velocity (mixed variables) were input jointly, the model's identification accuracy reached over 95%.In conclusion: The fault diagnosis model built upon the CNN architecture demonstrates strong feature extraction capabilities and high accuracy in fault type recognition. This validates that the CNN-based model can accurately identify fault types, providing an AI solution for the fault recognition of the HPHT Hydraulic Cubic Press hydraulic system.
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The intelligent control of the artificial diamond synthesis process is primarily achieved through the implementation of advanced computer control technology and intelligent control strategies to enable comprehensive and precise monitoring and control of key process parameters.1. Overall Intelligent Control System ArchitectureThe computer control system for the artificial diamond press (such as the Y-500 cubic press) mainly replaces the machine's original electrical control system. The press itself is composed of the electrical control system and the hydraulic system.Intelligent Functionality and Goals:Comprehensive Control: The system utilizes computer control technology to perform all-around control and monitoring of the entire artificial diamond production process, significantly improving the working reliability and production efficiency of the press machine.Core Functions: It possesses intelligent functions including logic analysis, mathematical calculation, optimal dynamic control, state detection, analysis and processing of abnormal situations, automatic process tracking, dynamic display, a user-friendly human-machine interface, and network communication.Software Technology: The field control computer software applies intelligent PID control theory, fuzzy PID control theory, and PID parameter self-tuning technology.Prediction and Advance Control: The fault analysis and processing module software includes a state prediction function. This allows the prediction of the development trends for the ram displacement, system pressure, and system heating power. Based on this analysis, the computer performs advance control over all executive systems to ensure stable and safe operation of the equipment.Components: The control system consists of pressurization control, heating control, ram displacement control, comprehensive analysis and processing, field monitoring, and central monitoring.2. Intelligent Control Strategies for Key Process ParametersThe synthesis outcome (yield and quality) of artificial diamond is largely determined by the appropriate matching of temperature and pressure. Intelligent control focuses on precise regulation of these variables.A. Pressurization Control (Pressure) – Using Fuzzy PID ControlPressurization control demands high precision and speed. The process requires multiple stages (2 to 6 segments) for supercharging and pressure holding. The pressure needs to be increased from approximately 10 MPa to around 90 MPa in segments over several minutes, and the overshoot cannot exceed 0.3 MPa. Control Strategy: A fuzzy-PID composite control method is utilized to enhance the accuracy of fuzzy control. The pressure control strategy employs a multi-modal segmented control algorithm which synthesizes the advantages of Proportional (P), Fuzzy, and Proportional-Integral (PI) control. Control Breakdown: Supercharging uses the main pump switch control, while pressure holding utilizes the auxiliary pump compensation with fuzzy PID control. Switching Mechanism: When the deviation exceeds a specific threshold, Proportional control is engaged for rapid tracking adjustment. When the deviation falls below the threshold, it switches to Fuzzy control to improve system damping characteristics and reduce overshoot. When the error (linguistic variable) is zero, it switches to PI control (the integrator is shut down when the absolute error is zero or saturation occurs).Robustness: Compared to traditional PID controllers, the Fuzzy PID controller enhances the system's robustness against external interference and internal parameter changes, reducing overshoot and improving dynamic characteristics.B. Heating Control (Power/Temperature) – Using Expert-based Intelligent Self-tuning PID ControlThe heating control process typically starts after the supercharging reaches 30 MPa, and involves multiple stages of heating and holding. Heating power control needs to be precise, but temperature exhibits a lagging nature due to the characteristics of the heat transfer medium (pyrophyllite, woven ribbon, alloy rams).Control Strategy: The heating power control adopts an expert-based intelligent self-tuning PID control algorithm based on pattern recognition.Intelligent Self-tuning Mechanism: When the output deviates from the setpoint or when the system is disturbed, pattern recognition is performed on the time characteristics of the system error (e). This identifies characteristic parameters of the response curve, such as overshoot, damping ratio, decay oscillation period, and rise time. The deviations between these measured characteristic parameters and their preset values are input into the expert system. These corrections are applied to the conventional PID controller, modifying its parameters to ensure the heating power response curve characteristics meet the technical requirements.Performance: Practical implementation confirms that this intelligent self-tuning PID algorithm ensures stable operation and satisfies the steady-state control accuracy and dynamic response indices for heating power.C. Ram Displacement ControlThe synchronization accuracy of the six rams during the liquid filling process is a critical index for diamond synthesis. It is required that the synchronization difference be less than 0.01 mm. Given the extremely short filling time (only 4 to 5 seconds), the system must accurately sample and process 20x6 sets of displacement data.Control Strategy: To ensure control accuracy, the system employs high-speed processing instructions, floating-point arithmetic instructions, and various anti-interference measures.3. Monitoring and Human-Machine InteractionField Monitoring: Field monitoring uses a touch-screen graphic display operating terminal. This terminal is easy to operate, displays clearly, and is reliable. It dynamically displays the operating conditions, including switching quantities, analog quantities, process operation curves, and fault alarm types. It also allows for setting parameters such as working parameters, displacement parameters, PID parameters, and temperature/pressure curves.Central Monitoring: Real-time and historical data from all press machines are transmitted via the field bus to the central monitoring computer. This enables production management and technical analysis, allowing staff to view and print the operating status and historical data of specific presses. The central monitoring system software is built using Kingview 6.5.
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