The intelligentized management of the heating electric power supply for the HPHT Hydraulic Cubic Press is realized by introducing an intelligentized controlling system. This research addresses the status quo in domestic cubic hinge presses where the level of automation is low, leading to the production of middle-to-low level diamond products. The system aims to solve the problems of low automation and unstable temperature fields during production, thereby facilitating the improvement of diamond production and quality.
1. Core Design Philosophy: Realizing Non-Constant Power "Curve Heating"
Traditional domestic HPHT Hydraulic Cubic Presses commonly use the constant power heating method. However, the resistance inside the synthesis cavity continuously changes, and as the synthesis time lengthens, the temperature inside the cavity becomes increasingly high. This makes it difficult to ensure the stability of the temperature field within the cavity, which clearly restricts the improvement of diamond grade and output.
Based on the practical experience of diamond synthesis, this research proposed a non-constant power heating scheme, meaning different power levels are applied according to different time segments during the entire synthesis process, thereby maintaining the relative stability of the temperature field within the synthesis cavity.
Time-Segment Control: The intelligent controller can control the original heating power supply according to the best process curve selected by the user. It enables control over current changes in time segments, making the heating process more compliant with the process characteristics required for the growth of different diamonds.
Controlled Temperature Field: During the production process, operators can raise or lower the current at any time according to actual needs, ensuring that the temperature field of the entire synthesis process is under a controlled status.
2. Technical Implementation: Digital Control Replacing Manual Adjustment
The core of intelligentized control involves replacing the traditional manual adjustment method with digital control.
Replacing Manual Adjustment: The original heating power supply uses PID adjustment to achieve stable output via negative feedback control. However, the manual setting is achieved by a potentiometer, which makes it impossible to realize the non-constant power curve heating method. This traditional method also involves significant human factors and poor repeatability.
Microprocessor Core: The intelligentized system takes a microprocessor (such as the AT89C51 single-chip microcomputer) as its core. The core handles program control, display, parameter input, data acquisition, D/A conversion, and switching quantities.
Digital Control Loop: The system uses the single-chip microcomputer to digitally control the voltage, replacing the manual adjustment of the potentiometer's center point voltage. The single-chip microcomputer performs digital control based on the set process curve and outputs the corresponding analog voltage value via the D/A converter.
Power Regulation: This analog voltage signal then drives the subsequent circuit through the power amplification circuit, regulating the output voltage of the heating power supply by changing the SCR (Silicon Controlled Rectifier) conduction angle.
3. Program and Algorithm Design: Ensuring Control Precision and Stability
The system utilizes precise program design and algorithms to ensure accuracy and anti-interference capability in harsh working environments.
Modular Design: The application software adopts a modular design, consisting of the main program, the interrupt service program, and the control algorithm program.
Timing Interrupt Control: The system uses the timing interrupt program (which generates an interrupt, for example, every 125ms) to complete control output and time accumulation. After the timing reaches 1s, the system decrements the set time value by one and determines whether to enter the control output of the next time segment.
Control Algorithms: Algorithms used include comparison control, number system conversion, and multi-byte multiplication and division. The reasonable application of these algorithms satisfies the system's requirement for precision and simplifies the program structure.
Anti-Interference Capability: Given the harsh working environment, the system uses a watchdog timer and voltage monitoring (such as the X5045 chip) to monitor the controller's operation status, preventing system abnormality or loss of control. Furthermore, "software trap" technology is set up in the application program. When the program loses control due to external interference, the trap processing program automatically restores the program, effectively improving the system's anti-interference ability.
4. System Functions and Characteristics
The intelligentized control system, upon practical implementation, demonstrates the following functions and advantages:
A. Mode Selection: The system can operate in manual or automatic control states as required.
B. Multi-Segment Curve Control: In the automatic control mode, it features the arbitrary setting and controlling function for 8 segments of the heating curve.
C. Real-time Fine-tuning: In automatic mode, it has the working curve translation fine-tuning function, allowing operators to fine-tune the working curve at any time according to need.
D. Parameter Management: Parameter settings feature a password management function, ensuring that only authorized personnel can change parameters or passwords.
E. Direct Display: Dynamic display technology is used to display the time segment, time value, and output value in real-time. The display is direct.
F. Comprehensive Advantages: The system is characterized by high controlling precision, easy adjustment, good repeatability, and stability, facilitating the improvement of diamond production and quality.