A vacuum box helium leak detection method

Abstract

The application provides a vacuum box helium leak detection method, comprising: obtaining a workpiece to be detected and placing it in a vacuum box, vacuumizing the vacuum box after automatically closing the box door, and filling high-pressure nitrogen into the workpiece to be detected to conduct pressure resistance strength and large-leak air tightness test; if the test is passed, pre-vacuumizing the workpiece to be detected to a set value, filling helium into the workpiece to be detected after the vacuum box and the workpiece to be detected reach a set vacuum degree, and judging the leak rate to be qualified or unqualified through helium mass spectrum detection; recycling the helium after detection is completed and recycling the helium, and realizing full automation of the detection process through PLC control and touch screen operation.

Description

Technical Field

[0001] This invention relates to the field of information technology, and in particular to a method for detecting helium leaks in a vacuum chamber. Background Technology

[0002] Industries such as aerospace, automotive manufacturing, and electronics have extremely high requirements for the accuracy of workpiece airtightness testing, as airtightness directly affects the safety and reliability of products; even the slightest leak can lead to equipment failure or safety accidents. In these fields, airtightness testing is not only a core part of quality control but also a key technology to ensure the normal operation of products in extreme environments. However, existing testing methods have significant shortcomings in practical applications, failing to meet the combined demands of high precision, high efficiency, and low cost, thus limiting the further development of industrial production.

[0003] Current airtightness testing methods often face the problem of insufficient cleanliness of the workpiece surface. Residual oil, dust, or other impurities may remain on the workpiece surface, interfering with the sensitivity of the testing equipment and causing leaks to be masked or misjudged. For example, in automobile manufacturing, the complex surfaces of engine components may have processing residues that affect test results, leading to inaccurate leak rate data. Furthermore, maintaining a stable vacuum environment during testing is difficult; ordinary vacuum systems are prone to pressure fluctuations due to equipment aging or poor sealing, thus affecting testing accuracy. These problems render existing methods inefficient and unreliable in demanding scenarios.

[0004] A deeper technical challenge lies in effectively controlling helium resource usage while achieving high-precision detection. Helium, a key tracer gas in leak detection, presents a challenge to the economic viability of the test due to its scarcity and high cost. In practice, helium is often used only once and then released without being recycled, leading to significant resource waste. For example, in electronic device manufacturing, detecting minute leaks requires large-volume helium injections, but traditional equipment lacks a recovery mechanism, resulting in high costs. Furthermore, frequent helium replenishment can interrupt the detection process and reduce production efficiency.

[0005] Therefore, achieving efficient helium utilization while ensuring workpiece surface cleanliness and a stable vacuum environment has become a key issue in the field of airtightness testing. This issue not only involves technological improvements in testing equipment but also requires breakthroughs in automated control and resource management to meet the comprehensive demands of industrial production for high precision, high efficiency, and low cost. Summary of the Invention

[0006] This invention provides a method for helium leak detection in a vacuum chamber, mainly comprising: The workpiece to be inspected is acquired and placed into a vacuum chamber. After the chamber door is automatically closed, the vacuum chamber is evacuated, and high-pressure nitrogen is simultaneously introduced into the workpiece to test its pressure resistance and large leakage tightness. If the test is passed, the workpiece is pre-evacuated to a set value, and after the vacuum chamber and the workpiece reach the set vacuum level, helium is introduced into the workpiece. Helium mass spectrometry is used to determine whether the leakage rate is qualified or unqualified. After the test is completed, the helium is recovered and recycled. The entire testing process is fully automated through PLC control and touch screen operation.

[0007] Furthermore, the process of evacuating the vacuum chamber and simultaneously filling the workpiece under inspection with high-pressure nitrogen for pressure resistance and large leak tightness testing includes: acquiring the workpiece under inspection and placing it into the vacuum chamber through a manual connection joint; pressing the start button and the vacuum chamber automatically descending and closing to seal; evacuating the vacuum chamber by opening a specific valve and filling the workpiece under inspection with high-pressure nitrogen, wherein the pressure of the high-pressure nitrogen is adjustable within a preset range; observing the pressure change inside the workpiece under inspection for a preset pressure holding time; if the pressure change exceeds the set range, it is judged as a large leak and an automatic alarm is triggered; if it is within the set range, it is judged as no large leak and the nitrogen is released; if no large leak is determined, the workpiece under inspection is pre-evacuated to a set value, wherein the set value is adjusted via a touch screen; and precisely controlling the vacuum chamber and the workpiece under inspection to reach a set vacuum level through a vacuum measuring device, wherein the pressure inside the vacuum chamber is lower than a preset threshold and the evacuation pressure of the workpiece under inspection is lower than another preset threshold.

[0008] Furthermore, the process of filling the workpiece with helium and determining whether the leak rate is acceptable or unacceptable using helium mass spectrometry includes: opening the leak detection valve after the vacuum chamber and the workpiece reach a set vacuum level, and filling the workpiece with helium at a set pressure, wherein the helium filling pressure is adjustable within a preset range; detecting the leak rate inside the vacuum chamber using a helium mass spectrometer leak detector, obtaining leak rate data and comparing it with a preset leak rate threshold, wherein the preset leak rate threshold is set by the system; if the leak rate data is lower than the preset leak rate threshold, it is judged as acceptable and a prompt is given; if it is higher than the preset leak rate threshold, it is judged as unacceptable and an alarm is triggered; for unacceptable cases, the system automatically recovers the helium and removes the helium background in the vacuum chamber and pipeline by filling with high-purity nitrogen; after the test is completed, the vacuum chamber is filled, the door is opened and lifted, and the acceptable workpiece is manually unloaded, wherein the entire process is coordinated by a PLC with the leak detector and the helium filling and recovery section.

[0009] Furthermore, the recovery and recycling of helium gas is fully automated through PLC control and touchscreen operation, including: opening a specific valve after testing to allow helium gas in the inspected workpiece to flow into a low-pressure recovery tank; extracting the remaining helium gas in the inspected workpiece using a vacuum pump and sending it into the recovery tank, while simultaneously compressing the helium gas in the recovery tank into a high-pressure storage tank using a compressor; monitoring the helium pressure and concentration in the high-pressure storage tank, and automatically opening a valve to replenish high-purity helium gas if it falls below a preset value; filtering the helium gas through a three-stage filtration device to ensure cleanliness, with the filtration accuracy reaching a preset level; and integrating the leak detector, vacuum chamber, and helium filling and recovery section with PLC control, displaying real-time vacuum level, pressure, and leak rate on the touchscreen, and recording pressure change data, where parameters are set via access permissions.

[0010] Furthermore, the step of evacuating the vacuum chamber by opening a specific valve and filling the inspected workpiece with high-pressure nitrogen includes: obtaining the internal dimensions of the vacuum chamber and adjusting them according to the shape of the inspected workpiece, wherein the volume of the vacuum chamber is determined by a protocol; opening the valve to evacuate the vacuum chamber to a pressure lower than a preset pressure, while simultaneously filling the inspected workpiece with high-pressure nitrogen to simulate the working environment; obtaining pressure sensor data to observe pressure changes during the pressure holding period, and passing if the changes are within a set range; if a large leak alarm is triggered, pressing the reset button will automatically release the gas from the workpiece, and the vacuum chamber will be filled and opened; and ensuring safe operation of the chamber door through a safety light curtain, wherein the height of the vacuum chamber above the ground is within a preset range.

[0011] Furthermore, the process of detecting leaks inside the vacuum chamber using a helium mass spectrometer to obtain leak rate data and compare it with a preset leak rate threshold includes: using a Roots vacuum pump set to evacuate the vacuum chamber to increase the pumping speed, and measuring the vacuum level through a vacuum gauge; after filling with helium, performing helium mass spectrometry detection through control valves and calibration components to obtain the real-time leak rate; if the leak rate is higher than the threshold, triggering the helium purging function to fill the vacuum chamber and pipelines with high-purity nitrogen to remove contamination; controlling the recovery rate to be no less than a preset ratio through a compressor and pump set; setting multiple sets of parameters through a touch screen and displaying qualified and unqualified results in real time, wherein the system has password protection and fault logging.

[0012] Furthermore, the step of compressing helium from the recovery tank to the high-pressure storage tank via a compressor includes: acquiring helium from the low-pressure recovery tank and compressing it via a compressor, wherein the high-pressure storage tank is equipped with a pressure sensor; replenishing helium from an external source if the concentration is lower than a preset value, controlling the process via a solenoid valve and a vacuum valve; treating the helium with a precision filter to prevent impurities from contaminating the inspected workpiece; using a PLC to coordinate the electrical control section to achieve interlocking protection, stopping operation and triggering an alarm if the protection device activates; and displaying data statistics and pressure change records on a touchscreen, wherein the system automatically stores the detection process data.

[0013] Furthermore, the fully automated detection process achieved through PLC control and touchscreen operation includes: integrating system components through a communication module to achieve coordinated control; setting operating parameters such as leak rate and detection time, and preventing modification through password protection; recording the time and triggering an alarm in case of a fault, including overload protection and overvoltage protection; indicating pass or fail through an audible and visual alarm, and ensuring safety features such as an emergency stop switch.

[0014] The technical solutions provided by the embodiments of the present invention may include the following beneficial effects: This invention discloses a vacuum chamber helium leak detection method, targeting high-precision workpiece airtightness testing scenarios in aerospace, automotive manufacturing, and electronic device industries. It solves the problems of low accuracy, slow efficiency, and high cost caused by insufficient workpiece surface cleanliness, unstable vacuum environment, and helium resource waste in traditional testing methods. This invention ensures surface cleanliness through workpiece pretreatment, achieves stable positioning using an adjustable vacuum chamber cavity and low-outgassing-rate fixtures, constructs a high-vacuum environment using a multi-stage vacuum pump system and precise pressure control technology, and achieves high-sensitivity leak rate detection using a helium mass spectrometer. Simultaneously, this invention integrates an automated control and helium recovery and recycling system, coordinating various components through a PLC, and combining real-time monitoring and parameter access management via a touchscreen to ensure efficient and reliable testing, achieving a helium recovery rate of over 90% and significantly reducing costs. Ultimately, this invention achieves high-precision, high-efficiency, and low-cost airtightness testing, meeting stringent industrial requirements and improving product quality and production efficiency. Attached Figure Description

[0015] Figure 1 This is a flowchart of a vacuum chamber helium leak detection method according to the present invention.

[0016] Figure 2 This is a logic control diagram for a vacuum chamber helium leak detection method according to the present invention.

[0017] Figure 3 This is a schematic diagram illustrating the system working principle of a vacuum chamber helium leak detection method according to the present invention.

[0018] Figure 4 This is a schematic diagram of the system helium recovery principle of a vacuum chamber helium leak detection method according to the present invention. Detailed Implementation

[0019] To further understand the content of this invention, a detailed description of the invention is provided in conjunction with the accompanying drawings and embodiments. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention. It should also be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0020] like Figure 1-3This embodiment of a vacuum chamber helium leak detection method specifically includes: This invention provides a vacuum chamber helium leak detection method. This method utilizes helium detection technology in a vacuum environment to accurately detect the airtightness of the workpiece under inspection, and is applicable to sealing inspection in fields such as aerospace, automotive manufacturing, and electronic devices.

[0021] Step S1: Obtain the workpiece to be inspected and place it into a vacuum chamber. After the chamber door is automatically closed, the vacuum chamber is evacuated. At the same time, high-pressure nitrogen is introduced into the workpiece to test its pressure resistance and air tightness.

[0022] In one embodiment, the process of acquiring the workpiece includes pretreatment and positioning. Before entering the detection system, the workpiece needs to be cleaned to ensure its surface is free of oil, dust, and other impurities, thus avoiding any impact on detection accuracy. The cleanliness of the workpiece's outer surface directly affects the establishment of the vacuum environment and the accuracy of helium detection. Cleaning typically employs solvent cleaning or ultrasonic cleaning methods, with the appropriate method selected based on the workpiece's material and degree of contamination.

[0023] Specifically, the process of placing the workpiece into the vacuum chamber requires consideration of the workpiece's geometry and dimensions. The vacuum chamber's interior is designed with an adjustable structure to accommodate workpieces of different sizes. The workpiece is fixed in a designated position within the vacuum chamber using specialized fixtures, ensuring stability during the inspection process. The fixtures are made of stainless steel or aluminum alloy with low outgassing rates to prevent additional gas release in a vacuum environment.

[0024] Step S11: Obtain the workpiece to be inspected and place it into the vacuum chamber through the manual connection joint. After pressing the start button, the vacuum chamber will automatically descend and close the door to seal.

[0025] The design of the connector is a key component of the testing system. The connector employs a quick-connect structure, enabling rapid assembly and disassembly while ensuring a tight seal. An internal sealing ring, made of fluororubber or silicone rubber, provides excellent temperature resistance and chemical stability. During connection, operators must ensure the contact surfaces between the connector and the workpiece are clean to avoid testing errors caused by poor sealing.

[0026] The automatic door closing mechanism of the vacuum chamber is achieved through a pneumatic or electric drive system. The chamber door employs a multi-point sealing structure to ensure good sealing during the vacuuming process. The sealing rings are O-rings made of nitrile rubber or fluororubber, capable of withstanding pressure differences under vacuum conditions. After the chamber door closes, the system automatically detects the sealing status and only begins subsequent vacuuming operations after confirming a good seal.

[0027] Step S12: Vacuum the vacuum chamber by opening a specific valve and fill the workpiece under inspection with high-pressure nitrogen gas, wherein the pressure of the high-pressure nitrogen gas is adjustable within a preset range.

[0028] The vacuum chamber evacuation process employs a multi-stage evacuation system. The initial evacuation uses a mechanical pump to quickly reduce the pressure inside the chamber to a medium vacuum level. The pumping speed of the mechanical pump is determined by the volume of the vacuum chamber, typically selecting a pump with a pumping speed 3 to 5 times the chamber volume. After reaching a medium vacuum, a molecular pump or diffusion pump is activated for high-vacuum evacuation, ultimately bringing the pressure inside the chamber to the required testing vacuum level.

[0029] The high-pressure nitrogen filling process requires precise control of pressure and flow rate. High-purity nitrogen (99.99%) is used as the nitrogen source to ensure a clean testing environment. Nitrogen enters the workpiece under test through a pressure reducing valve and a flow control valve, with pressure control accuracy reaching ±0.01 MPa. During filling, the system monitors the internal pressure changes of the workpiece in real time to ensure the filling pressure reaches the preset value.

[0030] Step S121: Obtain the inner dimensions of the vacuum chamber and adjust them according to the shape of the workpiece being inspected, wherein the volume of the vacuum chamber is determined by a protocol.

[0031] The vacuum chamber's internal cavity adjustment mechanism employs a modular design. The chamber's interior features movable partitions and support structures, allowing for adjustment based on the dimensions of the workpiece being inspected. This design accommodates workpieces of varying sizes while minimizing the effective volume of the vacuum chamber, thus maximizing vacuuming efficiency. Determining the internal cavity volume requires consideration of factors such as workpiece size, vacuuming time, and inspection accuracy.

[0032] In one possible implementation, the vacuum chamber volume is determined by a pre-defined protocol file. This file contains optimal vacuum chamber volume parameters for different workpiece types, and the system automatically calls the appropriate volume settings based on the workpiece type. This approach ensures the consistency and repeatability of the detection parameters, improving the reliability of the detection results.

[0033] Step S122: Open the valve to evacuate the vacuum chamber to a pressure lower than the preset pressure, and at the same time fill the workpiece under inspection with high-pressure nitrogen to simulate the working environment.

[0034] The timing and sequence of valve opening are crucial to the vacuuming process. The system first opens the coarse-pump valve and starts the mechanical pump to perform initial vacuuming of the vacuum chamber. When the vacuum level reaches a preset intermediate value, the coarse-pump valve is closed, the fine-pump valve is opened, and the high-vacuum pump is started to continue vacuuming. This staged vacuuming method effectively improves vacuuming efficiency and shortens detection time.

[0035] The introduction of high-pressure nitrogen simulates the pressure state of the workpiece under test in an actual working environment. The nitrogen pressure is set according to the actual working pressure of the workpiece, typically 1.2 to 1.5 times the working pressure, to verify the sealing performance of the workpiece under overpressure conditions. The inflation process is carried out slowly to avoid pressure shocks that could damage the workpiece.

[0036] Step S13: Observe the internal pressure change of the workpiece under inspection during the pressure holding preset time. If the pressure change exceeds the set range, it is judged as a major leak and an automatic alarm is triggered. If it is within the set range, it is judged as no major leak and nitrogen is released.

[0037] The holding time is set based on the workpiece volume and the expected detection accuracy. For small workpieces, the holding time is typically set to 30 seconds to 2 minutes, while for large workpieces, the holding time can be extended to 5 minutes or longer. During the holding period, the system monitors the internal pressure changes of the workpiece in real time using a high-precision pressure sensor, with a pressure measurement accuracy of 0.1 Pa.

[0038] The criteria for judging pressure changes are determined based on the workpiece type and sealing requirements. Generally, a pressure drop rate exceeding 1% of the initial pressure is considered a major leak. The major leak detection algorithm considers factors such as temperature compensation and system drift to ensure the accuracy of the judgment results. When a major leak is detected, the system immediately stops the detection process, activates the alarm device, and automatically records the fault information.

[0039] Step S14: If it is determined that there is no major leak, the workpiece under inspection is pre-vacuumed to a set value, wherein the set value is adjusted via a touch screen.

[0040] Pre-vacuuming is a crucial preparatory step before helium leak testing. Pre-vacuuming inside the workpiece removes residual nitrogen and other gases, creating favorable environmental conditions for subsequent helium filling. The target pressure for pre-vacuuming is typically set between 1 Pa and 10 Pa, with the specific value determined based on the workpiece's sealing requirements and testing accuracy.

[0041] The touchscreen interface provides intuitive parameter adjustment functions. Operators can set parameters such as the target pre-vacuum pressure, evacuation time, and evacuation rate via the touchscreen. The interface uses a graphical display to show the current vacuum level and evacuation progress in real time, facilitating operator monitoring of the testing process.

[0042] Step S15: The vacuum chamber and the workpiece under inspection are precisely controlled by the vacuum measuring device to reach the set vacuum level, wherein the pressure inside the vacuum chamber is lower than a preset threshold and the evacuation pressure of the workpiece under inspection is lower than another preset threshold.

[0043] The vacuum measuring device employs a combination of various types of vacuum gauges. A thermocouple vacuum gauge is used in the rough vacuum stage, with a measurement range of 0.1 Pa to 100,000 Pa. An ionization vacuum gauge is used in the high vacuum stage, with a measurement range of 0.0001 Pa to 1 Pa. This combination of gauges ensures measurement accuracy and reliability across the entire range.

[0044] Vacuum control employs a closed-loop control system. Based on the measurement results from the vacuum gauge, the system automatically adjusts the operating status of the vacuum pump and the valve opening to achieve precise vacuum control. The control algorithm uses a PID control strategy, enabling rapid response to changes in vacuum level and maintaining a stable vacuum environment. The pressure threshold inside the vacuum chamber is typically set to 0.1 Pa, and the evacuation pressure threshold for the inspected workpiece is set to 1 Pa.

[0045] Step S2: If the inspection passes, the workpiece under inspection is pre-evacuated to the set value. After the vacuum chamber and the workpiece under inspection reach the set vacuum level, helium is introduced into the workpiece under inspection. The leak rate is determined to be qualified or unqualified by helium mass spectrometry.

[0046] Helium detection is the core component of the entire leak detection process. Helium, as a detection medium, has advantages such as small molecular weight, good chemical inertness, and ease of detection. In a vacuum environment, helium can rapidly penetrate into tiny leak channels, and extremely low concentrations of helium can be detected using a helium mass spectrometer leak detector, enabling high-precision leak rate measurement.

[0047] The working principle of a helium mass spectrometer leak detector is based on mass spectrometry analysis technology. Helium molecules are ionized into helium ions in the ionization chamber. Under the influence of a magnetic field, the helium ions are separated according to their mass-to-charge ratio. The helium ions are collected by a collector and converted into an electrical signal. The intensity of the electrical signal is proportional to the helium concentration, and a precise leak rate value can be obtained through signal processing circuitry.

[0048] Step S21: After the vacuum chamber and the workpiece under inspection reach the set vacuum level, open the leak detection valve and fill the workpiece under inspection with helium gas at a set pressure, wherein the helium filling pressure is adjustable within a preset range.

[0049] The leak detection valve is designed with a precision regulating valve to achieve accurate control of the helium flow rate. The valve's internal structure uses a needle valve, and the helium flow rate is controlled by adjusting the needle valve's opening. The valve is made of stainless steel, and its inner surface undergoes electrolytic polishing to ensure surface smoothness and chemical stability. The valve's sealing performance directly affects the detection accuracy; the sealing material uses either an all-metal seal or a polymer seal.

[0050] The helium filling pressure is determined based on the structure and sealing requirements of the workpiece being inspected. For thin-walled workpieces, the filling pressure is typically set between 50 kPa and 200 kPa to avoid deformation caused by excessive pressure. For thick-walled or high-strength workpieces, the filling pressure can be set to 500 kPa or even higher to improve detection sensitivity. The helium filling process employs a slow filling method, with the filling rate controlled between 10 kPa / s and 50 kPa / s.

[0051] Step S211: Use a Roots vacuum pump set to evacuate the vacuum chamber to increase the pumping speed, and measure the vacuum level through a vacuum gauge.

[0052] The configuration of a Roots vacuum pump set is determined based on the vacuum chamber volume and evacuation time requirements. Roots pumps are characterized by high pumping speed and high ultimate vacuum, making them particularly suitable for rapid evacuation of large-volume vacuum chambers. Pump sets typically employ a combination of a Roots pump and a mechanical pump, with the mechanical pump serving as the backing pump and the Roots pump as the main pump. This configuration allows the vacuum chamber to be evacuated to the required vacuum level in a relatively short time.

[0053] The installation location and number of vacuum gauges are determined based on the structure of the vacuum chamber. To accurately reflect the vacuum distribution within the chamber, multiple vacuum gauges are typically installed at different locations. The selection of vacuum gauges considers factors such as measurement range, accuracy, and response time. In helium leak detection applications, where high measurement accuracy is required, ionization vacuum gauges or capacitive thin-film vacuum gauges are usually selected.

[0054] Step S22: The vacuum chamber is tested using a helium mass spectrometer leak detector to obtain leak rate data and compare it with a preset leak rate threshold, wherein the preset leak rate threshold is set by the system.

[0055] The helium mass spectrometer leak detector is connected to a vacuum chamber via a sampling line to continuously sample the gas inside the chamber. The design of the sampling line needs to balance the line impedance and response time. A line diameter that is too small will increase flow resistance and affect the detection response speed, while a line diameter that is too large will increase the dead volume of the system and affect detection accuracy. Stainless steel tubing with an inner diameter of 6mm to 12mm is typically chosen for the sampling line.

[0056] Leakage rate data is acquired using real-time sampling and data processing techniques. The leak detector collects multiple data points per second, and noise interference is eliminated through digital filtering and signal processing algorithms to obtain stable and reliable leak rate values. Data processing algorithms include moving average filtering and Kalman filtering, which effectively improve measurement accuracy and stability.

[0057] Step S221: After filling with helium, helium mass spectrometry is performed through the control valve and calibration section to obtain the real-time leak rate.

[0058] The control valve system includes multiple solenoid valves and manual valves for switching gas flow paths and regulating flow. The solenoid valves feature a fast-response design with a response time of less than 100 milliseconds, enabling precise flow path control. The manual valves, used for flow path adjustment during system maintenance and calibration, employ a precision needle valve design, offering excellent regulating characteristics and sealing performance.

[0059] The calibration section is a crucial component for ensuring testing accuracy. The calibration system includes a standard leak orifice, a calibration gas source, and a calibration flow path. The leak rate of the standard leak orifice is precisely calibrated, serving as the benchmark for leak detector calibration. The calibration process is performed automatically before each test, ensuring the measurement accuracy and stability of the leak detector. Calibration data is automatically recorded and used to correct test results.

[0060] Step S23: If the leakage rate data is lower than the preset leakage rate threshold, it is judged as qualified and a prompt is given; if it is higher than the preset leakage rate threshold, it is judged as unqualified and an alarm is triggered.

[0061] The leakage rate threshold is set based on the technical requirements and application of the inspected workpiece. For seals in the aerospace industry, the leakage rate threshold is typically set between 10^-9 Pa·m³ / s and 10^-10 Pa·m³ / s. For seals in the automotive industry, the leakage rate threshold can be set between 10^-6 Pa·m³ / s and 10^-8 Pa·m³ / s. Threshold setting requires consideration of a balance between inspection accuracy, production cost, and product reliability.

[0062] The results are displayed using a combination of methods. Passing results are indicated by a green indicator light and a short buzzer sound, while failing results are indicated by a red indicator light and a long buzzer sound. Simultaneously, the test results are displayed on the touchscreen in numerical and graphical formats, including the measured leak rate, threshold setting, and pass / fail judgment. Test data is automatically saved to a database for easy quality traceability and statistical analysis.

[0063] In step S24, for non-compliant cases, the system automatically recovers helium and removes the helium background in the vacuum box and pipeline by filling it with high-purity nitrogen.

[0064] The helium recovery system is designed with economic and environmental requirements in mind. As a rare gas, helium's recovery and reuse can significantly reduce testing costs. The recovery system includes recovery pipelines, a recovery tank, and a purification unit. Helium from defective workpieces enters the recovery tank through the recovery pipelines, is purified, and then reused for testing. The recovery rate typically reaches over 90%.

[0065] Helium background removal is a crucial step in ensuring the accuracy of subsequent detections. Helium has strong permeability and adsorption properties in vacuum systems, and residual helium can affect the accuracy of subsequent tests. The removal process uses high-purity nitrogen replacement gas with a purity of no less than 99.999% and a helium content of less than 1 ppm. The replacement process requires multiple cycles to ensure that the helium background is reduced to an acceptable level.

[0066] Step S25: After the test is completed, the vacuum chamber is filled with gas, the door is opened and the workpiece is lifted, and qualified workpieces are manually unloaded. The entire process is coordinated by the PLC with the leak detector and the helium filling and recovery section.

[0067] The vacuum chamber's inflation and opening process employs a safety interlock design. The system first confirms the complete completion of the testing process and helium recovery before initiating the inflation process. Dry air or nitrogen is used for inflation, and the inflation rate is controlled within an appropriate range to avoid impact on the workpiece due to excessively rapid inflation. When the pressure inside the vacuum chamber approaches atmospheric pressure, the safety interlock is released, and the chamber door opens automatically.

[0068] The PLC control system adopts a distributed control architecture, with the main controller responsible for overall process coordination and each subsystem equipped with an independent control module. The control system has comprehensive fault diagnosis and safety protection functions, capable of automatically shutting down and issuing alarms in abnormal situations. The human-machine interface uses a touchscreen design, providing an intuitive operating interface and real-time status display.

[0069] Step S3: After the test is completed, the helium gas is recovered and recycled. The test process is fully automated through PLC control and touch screen operation.

[0070] A helium recycling system is an important measure to improve the economic efficiency of testing. The system includes helium recovery, purification, storage, and reuse. The recovered helium undergoes multi-stage purification to remove moisture, oxygen, and other impurities, restoring its purity to the required testing levels. The purified helium is stored in a high-pressure storage tank for subsequent testing. The entire recycling process is automated, reducing human intervention and operational errors.

[0071] Step S31: After the test is completed, open a specific valve to allow helium gas inside the tested workpiece to flow into the low-pressure recovery tank.

[0072] The design volume of the low-pressure recovery tank is determined based on the internal volume of the workpiece being inspected and the helium filling pressure. The recovery tank is typically made of stainless steel, with an inner surface treated by electrolytic polishing to ensure a smooth surface and low outgassing rate. The recovery tank is equipped with pressure and temperature sensors to monitor the gas state inside the tank in real time. The tank's design pressure is typically 1 MPa, with the operating pressure controlled below 0.5 MPa to ensure safe operation.

[0073] The opening of specific valves is controlled by a program, automatically executed according to a preset time sequence and pressure conditions. Before opening the valve, the system first checks the pressure status of the recovery tank to ensure sufficient volume to receive helium. The valve opening process is slow to avoid sudden pressure changes that could impact the system. The opening speed is controlled by the rotational speed of the electric actuator, typically set to open by 10% to 20% per second.

[0074] In one embodiment, the helium inflow process is driven by differential pressure. The helium pressure inside the workpiece being inspected is higher than the pressure in the recovery tank, creating a pressure difference that drives the helium flow. During the flow, the system monitors the pressure balance. When the pressures on both sides are close to equilibrium, an auxiliary extraction device is activated to ensure the integrity of helium recovery. The flow pipeline uses a large-diameter design to reduce flow resistance and improve recovery efficiency.

[0075] Step S32: The remaining helium gas inside the workpiece under inspection is extracted by a vacuum pump and sent to a recovery tank. At the same time, the helium gas in the recovery tank is compressed to a high-pressure storage tank by a compressor.

[0076] The selection of a vacuum pump considers factors such as pumping speed, ultimate vacuum level, and helium compatibility. For helium recovery applications, screw vacuum pumps or Roots vacuum pumps are typically chosen, as these pumps offer good helium extraction capabilities and low backflow rates. The pumping speed is determined based on the internal volume of the workpiece and the required recovery time; generally, a vacuum pump with a pumping speed 5 to 10 times the workpiece volume is selected.

[0077] The extraction of residual helium needs to take into account the complexity of the workpiece's internal structure. For workpieces with complex internal cavities, helium may stagnate in dead corners or narrow channels. The extraction process employs a multi-stage extraction method: first, rapid extraction is performed to remove most of the helium, followed by fine extraction to remove any remaining helium. The completion status of the entire extraction process is determined by a combination of pressure monitoring and time control.

[0078] The compressor system employs a multi-stage compression design, capable of compressing low-pressure helium gas to a high-pressure state. The first stage of compression reduces the low-pressure helium gas in the recovery tank to a medium pressure, while the second stage further increases the pressure to the storage requirements. During compression, the compression temperature needs to be controlled to prevent overheating from affecting the helium purity. The compressor is equipped with a cooling system, using either water or air cooling to control the compression temperature.

[0079] Step S321: Obtain helium gas from the low-pressure recovery tank and compress it using a compressor, wherein the high-pressure storage tank is equipped with a pressure sensor.

[0080] Helium in the low-pressure recovery tank is extracted from the bottom to ensure full utilization of the helium. The extraction pipeline is designed with an inverted U-shape to prevent liquid impurities from entering the compressor. The pipeline inner diameter is determined according to the compressor's intake requirements, typically choosing a diameter of 25mm to 50mm to ensure sufficient gas flow. During extraction, the system monitors the pressure changes in the recovery tank, and stops extraction when the pressure drops to a preset lower limit.

[0081] The compressor's operating parameters are optimized based on the physical properties of helium. Helium has a high specific heat, resulting in a significant temperature rise during compression; therefore, multi-stage compression and intercooling are necessary to control the temperature. The compression ratio is typically set between 3 and 5 to ensure compression efficiency while avoiding excessively high compression temperatures. The compressor's exhaust temperature is controlled below 80 degrees Celsius to ensure helium quality and equipment safety.

[0082] The pressure sensor in the high-pressure gas storage tank uses a high-precision pressure transmitter with a measurement accuracy of 0.1% of full scale. The sensor is mounted on top of the tank to avoid interference from liquid impurities. The sensor signal is input to the PLC system via an analog input module, enabling real-time pressure monitoring and control. The pressure data is used to control the compressor's start / stop and regulate the compression process.

[0083] Step S33: Monitor the helium pressure and concentration in the high-pressure storage tank. If it is lower than the preset value, automatically open the valve to replenish high-purity helium.

[0084] Helium concentration is monitored using gas chromatography. The analytical instrument is equipped with a thermal conductivity detector, enabling precise measurement of helium concentration in the gas mixture. A sampling system periodically extracts gas samples from the storage tank, which are then analyzed by the analytical instrument. The analysis results are transmitted to the control system in real time for helium quality monitoring and replenishment decisions.

[0085] The frequency of concentration monitoring is determined based on system usage and helium consumption. During continuous monitoring operations, the monitoring frequency is set to once per hour, while during intermittent operations, the frequency can be reduced to once per day. Monitoring data is automatically recorded and trend charts are generated to facilitate analysis of helium quality variation patterns and prediction of replenishment needs.

[0086] The automatic replenishment system includes components such as a high-purity helium source, a pressure reducing valve, a flow control valve, and a safety valve. The high-purity helium source typically uses a steel cylinder or a liquid helium Dewar flask, with a helium purity of no less than 99.999%. The pressure reducing valve reduces the high-pressure helium to an appropriate pressure, and the flow control valve precisely controls the replenishment flow rate. The replenishment process employs a slow filling method to avoid pressure shocks and temperature changes affecting the storage tank.

[0087] Step S322: If the concentration is lower than the preset value, helium is replenished from an external source, and the process is controlled by a solenoid valve and a vacuum valve.

[0088] The selection of an external helium source considers factors such as purity, pressure, and supply stability. Industrial-grade high-purity helium typically has a purity of 99.999%, which meets leak detection requirements. Helium supply is achieved through a multi-cylinder combination system using a manifold system for continuous supply. The manifold is equipped with an automatic switching device that automatically switches to a backup cylinder group when the pressure of one group of cylinders drops, ensuring uninterrupted supply.

[0089] The solenoid valve system features an explosion-proof design, suitable for controlling inert gases such as helium. The valve is made of stainless steel, and the seals are made of fluororubber or metal, ensuring long-term reliability. The solenoid valve has a response time of less than 50 milliseconds, enabling precise flow control. Valve opening is controlled via pulse width modulation, achieving continuously adjustable flow characteristics.

[0090] Vacuum valves are used for system isolation and maintenance operations. The valves feature a bellows seal design, providing excellent vacuum sealing performance. They can be operated manually or electrically. Manual valves are used for isolation operations during system maintenance, while electric valves are used for on / off operations in automated control processes. Valve selection considers parameters such as nominal diameter, pressure rating, and sealing performance.

[0091] Step S34: Helium gas is filtered through a three-stage filtration device to ensure cleanliness, wherein the filtration accuracy reaches a preset level.

[0092] The three-stage filtration system employs a progressive filtration design, with each stage increasing in filtration precision. The first-stage filter uses a coarse filter element with a filtration precision of 10 microns, primarily removing larger particulate impurities and oil mist. The filter element is made of sintered stainless steel or polytetrafluoroethylene (PTFE) material, exhibiting excellent chemical stability and temperature resistance.

[0093] The secondary filter uses a medium-efficiency filter element with a filtration accuracy of 1 micron, further removing fine particles and aerosols. The filter element is made of glass fiber or polypropylene, offering high filtration efficiency and low pressure drop. The filter housing is made of stainless steel and is designed to withstand the system's operating pressure of 2 MPa.

[0094] The three-stage filter uses high-efficiency filter elements with a filtration accuracy of 0.1 microns, capable of removing the vast majority of particulate contaminants. The filter elements utilize PTFE membranes or ultra-fine glass fiber materials, achieving a filtration efficiency of over 99.99%. The filter is equipped with a differential pressure indicator to monitor the clogging status of the filter elements in real time. When the differential pressure exceeds a set value, an automatic alarm is triggered to prompt replacement of the filter elements.

[0095] In step S35, the PLC controls the integrated leak detector, vacuum chamber, and helium recovery section, displays the real-time vacuum level, pressure, and leak rate via a touch screen, and records pressure change data, with parameters set by permissions.

[0096] The PLC control system adopts a modular design. The main controller is responsible for the overall process coordination and management, while each subsystem is equipped with a dedicated control module. The main controller uses a high-performance PLC with abundant input / output interfaces and powerful data processing capabilities. The control program uses a structured programming approach, decomposing complex control logic into multiple functional modules to improve program maintainability and scalability.

[0097] The leak detector is integrated via a standard communication interface, supporting multiple communication methods such as RS485 and Ethernet. The communication protocol uses Modbus or a custom protocol to enable remote setting of leak detector parameters and real-time data acquisition. Integrated functions include leak detector start / stop control, detection parameter setting, leak rate data reading, and fault status monitoring.

[0098] The vacuum chamber control module is responsible for the automated operation of the vacuum system, including the start / stop control of the vacuum pump, the on / off control of valves, and the monitoring and control of the vacuum level. The control module is equipped with multiple analog input interfaces to receive measurement signals from the vacuum gauge. The control algorithm employs a PID control strategy to achieve precise vacuum level control and rapid response.

[0099] The control of the helium charging and recovery section includes the coordinated control of the helium supply system, recovery system, and purification system. The control module monitors the operating status of each system and automatically switches operating modes according to the needs of the detection process. The helium supply is precisely regulated through a flow control valve, and the recovery process is completed by combining pressure balancing and time control.

[0100] The touchscreen human-machine interface uses an industrial-grade touchscreen, offering excellent environmental adaptability and long-term stability. The interface design employs a graphical approach, intuitively displaying the system's operating status and testing data. The main interface displays key parameters such as the current testing stage, vacuum level, pressure, and leak rate. The historical data interface provides data query and trend analysis functions, facilitating quality analysis and fault diagnosis.

[0101] Real-time data display combines numerical and graphical methods. Numerical displays provide precise numerical information, while graphical displays offer intuitive trends. The data refresh rate is set to once per second to ensure real-time data accuracy. Display precision is determined based on the characteristics of the measured parameters: vacuum level is 0.01 Pa, pressure is 0.1 kPa, and leak rate is 10^-11 Pa·m³ / s.

[0102] Pressure change data is recorded using high-speed data acquisition, with a sampling frequency exceeding 10 times per second. Recorded data includes timestamps, pressure values, temperature values, and system status. Data storage utilizes a relational database, supporting large-capacity data storage and fast retrieval. A data backup function ensures data security by periodically backing up data to external storage devices.

[0103] Parameter access control employs a multi-level permission management system. Operators can only view test data and execute standard test procedures, but cannot modify system parameters. Engineers can modify test parameters and system configurations, but password verification is required. Administrators have the highest level of privileges and can modify all parameters and system settings. Access control is implemented through user login and password verification, with login information automatically recorded for easy auditing and tracing.

[0104] Step S4: Integrate system components through the communication module to achieve coordinated control.

[0105] The communication module employs industrial Ethernet technology, supporting the TCP / IP protocol stack to achieve high-speed data exchange between various system components. The network topology adopts a star structure, with the main controller serving as the network center, and each subsystem connected to the network via switches. The network transmission rate reaches 100Mbps, meeting the requirements for real-time control and large-volume data transmission.

[0106] The integration of system components includes both hardware integration and software integration. Hardware integration is achieved through standardized interfaces, with each component using a unified electrical and mechanical interface standard. Software integration is achieved through unified communication protocols and data formats, ensuring compatibility and interoperability between equipment from different manufacturers.

[0107] The coordinated control algorithm employs a distributed control strategy, where each subsystem maintains relatively independent control functions, and the main controller is responsible for global coordination and optimization. The control algorithm considers the mutual influences and constraints between subsystems, achieving overall performance optimization through optimization algorithms. The implementation of coordinated control includes functions such as timing control, logic control, and safety interlocking.

[0108] In one possible implementation, the communication module supports remote monitoring and diagnostic functions. Through an internet connection, technicians can remotely access the system to adjust parameters and diagnose faults. Remote access utilizes VPN technology to ensure data transmission security. Remote diagnostic functions include system status monitoring, fault analysis, and maintenance recommendations.

[0109] Step S5: Set operating parameters such as leak rate and detection time, and prevent modification by password protection.

[0110] The setting of operating parameters includes several categories such as detection parameters, control parameters, and safety parameters. Detection parameters include leak rate threshold, detection time, and helium pressure, which directly affect the accuracy and reliability of the detection results. Control parameters include vacuum level setpoint, vacuuming time, and charging rate, which affect the efficiency and stability of the detection process.

[0111] Setting the leak rate threshold requires consideration of the technical requirements and application environment of the inspected workpiece. Leak rate requirements vary significantly depending on the type of workpiece, and the system provides multiple preset parameters for selection. The parameter setting interface combines drop-down menus and numerical input, offering both standard options and allowing for custom settings. After parameter settings are completed, the system automatically performs a validity check to prevent incorrect parameter settings.

[0112] The testing time is set based on a balance between testing accuracy and production efficiency. A longer testing time can improve accuracy but reduce production efficiency. The system offers three modes: rapid testing, standard testing, and precision testing, each with a corresponding testing time setting. Rapid testing is suitable for batch production, with a testing time of 2 to 5 minutes. Standard testing is suitable for routine quality control, with a testing time of 5 to 10 minutes. Precision testing is suitable for high-requirement products, with a testing time of 10 to 20 minutes.

[0113] The password protection function employs multi-layered encryption technology to ensure the security of parameter settings. Passwords must be a combination of letters, numbers, and special characters, and must be at least 8 characters long. The system supports password strength checks, requiring passwords to have sufficient complexity. Passwords are valid for 3 months, after which they must be forcibly replaced. If a password is entered incorrectly more than 3 times, the system will automatically lock for 30 minutes to prevent malicious attacks.

[0114] Step S6: If a fault occurs, record the time and trigger an alarm, including overload protection and overvoltage protection.

[0115] The fault detection system employs a multi-layered monitoring mechanism, encompassing both hardware and software monitoring. Hardware monitoring, implemented through sensors and detection circuits, detects anomalies in physical parameters such as voltage, current, temperature, and pressure. Software monitoring, achieved through program logic, detects software faults related to system operation, communication status, and data anomalies.

[0116] The fault logging function uses an event log to record in detail the time, type, location, and related parameters of each fault. Recorded information includes fault codes, fault descriptions, system status snapshots, and operator information. Fault records are automatically saved to non-volatile memory and will not be lost even if the system is powered off. The record capacity is sufficient to store fault information for more than one year, and it supports querying and statistics by time, type, and other criteria.

[0117] The overload protection function monitors the load status of each component in the system and automatically takes protective measures when the load exceeds the rated value. Motor overload protection is achieved through current monitoring; when the current exceeds the set value, the machine automatically shuts down and an alarm is triggered. Vacuum pump overload protection is achieved through temperature and vibration monitoring; when the temperature or vibration exceeds the limit, the machine automatically shuts down for protection. The overload protection action threshold is determined based on the equipment specifications and operating environment, ensuring equipment safety while preventing false triggering.

[0118] The overpressure protection function monitors the pressure status of each part of the system to prevent overpressure from harming equipment and personnel. Gas pipelines are equipped with safety valves that automatically release pressure when it exceeds a set value. The vacuum system is equipped with a vacuum breaker valve to prevent excessive vacuum from damaging equipment. Pressure monitoring employs a redundant design, equipped with both primary and backup pressure sensors to improve monitoring reliability.

[0119] Step S7: Use an audible and visual alarm to indicate whether the test is qualified or not, and ensure that safety features such as emergency stop switches are in place.

[0120] The audible and visual alarms feature an industrial-grade design, offering excellent environmental adaptability and long-term reliability. The audible alarms utilize buzzers or electronic speakers with adjustable volume and settable frequency. The visual alarms employ LED indicator lights, characterized by high brightness and long lifespan. The installation location of the alarms is carefully considered within the operator's line of sight and hearing range to ensure timely delivery of alarm information.

[0121] A successful alarm is indicated by a green indicator light and a short beep, providing the operator with a clear success signal. A failed alarm is indicated by a red indicator light and a continuous beep, drawing the operator's attention. The duration of the alarm signal is set, typically from 10 to 30 seconds. An alarm confirmation function allows the operator to manually stop the alarm signal, avoiding prolonged noise interference.

[0122] The safety features include multiple safety measures such as an emergency stop switch, safety light curtains, and protective door interlocks. The emergency stop switch uses a mushroom-shaped button design, is red in color, and is installed in a location easily accessible to operators. After the emergency stop switch is activated, the system immediately stops all moving parts, cuts off the dangerous power supply, and remains in a safe state until manually reset.

[0123] The safety light curtain is installed at the opening of the vacuum chamber and automatically shuts down to protect the system when an object enters the hazardous area. The light curtain uses infrared detection technology, achieving millimeter-level accuracy. The installation height and detection range of the light curtain are determined based on the equipment structure and safety requirements. In the event of a light curtain malfunction, the system automatically enters a safety mode to prevent safety function failure.

[0124] The safety door interlock ensures that the safety door remains closed during equipment operation and automatically shuts down the equipment when the door is opened. The interlock switch uses a magnetic or mechanical switch and features anti-tampering and anti-bypass capabilities. The interlock circuit employs a safety relay design, meeting safety standards. Interlock functionality is tested regularly to ensure its effectiveness.

[0125] like Figure 3 In helium filling and large leak detection mode: Place the workpiece into the vacuum chamber, then connect the workpiece to the system, press the dual start button, the chamber door will close automatically, and the remaining work will be completed automatically by the system.

[0126] After the chamber door is closed, the system opens V1 and V6, closes V2, V4, V5, V6, V7, and V8, evacuates the vacuum chamber, and fills the workpiece with high-pressure nitrogen.

[0127] Hold the pressure for a few seconds and observe the pressure change inside the workpiece. If the pressure change is within the set range, it means that there is no major leakage in the workpiece. Otherwise, it means that there is a major leakage in the workpiece. The system will automatically give an audible and visual alarm. The user presses the confirmation button and the system ends the test. In micro-leak detection mode: If no large leak is found, when the vacuum values ​​of both the vacuum chamber and the workpiece reach the required levels (which can be set on-site, such as 20Pa for the vacuum chamber and 1000Pa for the workpiece absolute pressure), helium gas at the set pressure is introduced into the workpiece to simulate the workpiece's working environment for micro-leak detection. If the workpiece is defective, the system will alarm; otherwise, the system will provide a prompt. For defective products, the system will issue an alarm signal; if no small leak is found, the system will automatically proceed to the next step.

[0128] like Figure 4 Helium recovery: After the micro-leakage detection is passed, the system automatically enters the recovery process. The helium charging and recovery system workflow is shown in the diagram. (The helium charging process is as follows: After evacuating the workpiece by opening V3, close V3, open V1, and charge the workpiece with helium until the specified pressure is reached, then close V1.) After leak detection, open V2, and the helium inside the workpiece automatically flows into the low-pressure recovery tank. Then close V2, open V3, and the mechanical pump extracts the remaining helium from the workpiece and sends it to the recovery tank. Simultaneously, the main compressor compresses the helium in the recovery tank to the storage tank. Because 100% recovery is impossible (recovery rate is higher than 98%), when the pressure or concentration in the storage tank is lower than the specified value, V6 needs to be opened to replenish helium to maintain sufficient pressure and concentration of helium in the storage tank.

[0129] Based on the embodiments of the present invention described above, and through the above description, those skilled in the art can make various changes and modifications without departing from the technical concept of the present invention. The technical scope of the present invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A method for detecting helium leaks in a vacuum chamber, characterized in that, include: The workpiece to be inspected is obtained and placed into a vacuum chamber. After the chamber door is automatically closed, the vacuum chamber is evacuated. At the same time, high-pressure nitrogen is introduced into the workpiece to test its pressure resistance and air tightness. If the inspection passes, the workpiece under inspection is pre-evacuated to the set value, and after the vacuum chamber and the workpiece under inspection reach the set vacuum level, helium is filled into the workpiece under inspection. The leak rate is determined to be qualified or unqualified by helium mass spectrometry. After the test is completed, the helium gas is recovered and reused. The test process is fully automated through PLC control and touch screen operation.

2. The vacuum chamber helium leak detection method as described in claim 1, characterized in that, The process of evacuating the vacuum chamber and simultaneously filling the workpiece under test with high-pressure nitrogen gas for pressure resistance and large leakage tightness testing includes: The workpiece to be inspected is obtained and placed into the vacuum chamber through a manual connection joint. After pressing the start button, the vacuum chamber automatically descends, closes, and seals. The vacuum chamber is evacuated by opening a specific valve, and high-pressure nitrogen is introduced into the workpiece being inspected. The pressure of the high-pressure nitrogen is adjustable within a preset range. The pressure holding time is preset to observe the internal pressure change of the inspected workpiece. If the pressure change exceeds the set range, it is judged as a major leak and an automatic alarm is triggered. If it is within the set range, it is judged as no major leak and nitrogen is released. If no major leak is determined, the workpiece under inspection is pre-vacuumed to a set value, which is adjusted via a touch screen. The vacuum chamber and the workpiece under inspection are precisely controlled by a vacuum measuring device to reach the set vacuum level, wherein the pressure inside the vacuum chamber is lower than a preset threshold, and the evacuation pressure of the workpiece under inspection is lower than another preset threshold.

3. The vacuum chamber helium leak detection method as described in claim 1, characterized in that, The process of filling the workpiece with helium gas and determining whether the leak rate is acceptable or unacceptable using helium mass spectrometry includes: After the vacuum chamber and the workpiece under inspection reach the set vacuum level, the leak detection valve is opened, and helium gas at a set pressure is introduced into the workpiece under inspection. The helium filling pressure is adjustable within a preset range. The leak rate inside the vacuum chamber is detected by a helium mass spectrometer, and the leak rate data is compared with a preset leak rate threshold, which is set by the system. If the leakage rate data is lower than the preset leakage rate threshold, it is judged as qualified and a prompt is given; if it is higher than the preset leakage rate threshold, it is judged as unqualified and an alarm is triggered. In case of non-compliance, the system automatically recovers helium and removes the helium background in the vacuum box and pipeline by filling it with high-purity nitrogen; After the test is completed, the vacuum chamber is filled with gas, the door is opened and lifted, and qualified workpieces are manually unloaded. The entire process is coordinated by a PLC with a leak detector and a helium filling and recovery unit.

4. The vacuum chamber helium leak detection method as described in claim 1, characterized in that, The process of recovering and recycling helium gas, and automating the detection process through PLC control and touchscreen operation, includes: After the test is completed, a specific valve is opened to allow helium gas inside the tested workpiece to flow into the low-pressure recovery tank. The remaining helium gas inside the workpiece under inspection is extracted by a vacuum pump and sent to a recovery tank. At the same time, the helium gas in the recovery tank is compressed to a high-pressure storage tank by a compressor. Monitor the helium pressure and concentration in the high-pressure storage tank. If it is lower than the preset value, automatically open the valve to replenish high-purity helium. Helium gas is filtered through a three-stage filtration system to ensure cleanliness, with the filtration precision reaching a preset level. The PLC control integrates the leak detector, vacuum chamber, and helium recovery unit. It displays real-time vacuum level, pressure, and leak rate via a touch screen and records pressure change data. Parameters can be set by user permissions.

5. The vacuum chamber helium leak detection method as described in claim 2, characterized in that, The process of evacuating the vacuum chamber by opening a specific valve and then filling the workpiece under inspection with high-pressure nitrogen includes: Obtain the inner cavity size of the vacuum chamber and adjust it according to the shape of the workpiece to be inspected. The volume of the vacuum chamber is determined by agreement; Open the valve to evacuate the vacuum chamber to a pressure lower than the preset pressure, and at the same time, fill the workpiece to be inspected with high-pressure nitrogen to simulate the working environment; Obtain the data of the pressure sensor and observe the pressure change during the pressure holding period. If the change is within the set range, it passes; If a large leak alarm occurs, press the reset button and the workpiece will automatically deflate, and the vacuum chamber will be inflated and the door will be opened; Ensure the safety of the door operation through the safety light curtain. The height of the vacuum chamber from the ground is within the preset range.

6. The vacuum chamber helium leak detection method as described in claim 3, characterized in that, The vacuum chamber is detected by a helium mass spectrometer leak detector, and the leak rate data is obtained and compared with the preset leak rate threshold, including: Use a Roots vacuum pump set to evacuate the vacuum chamber to improve the pumping speed, and measure the vacuum degree through a vacuum gauge tube; After filling with helium, perform helium mass spectrometry detection through the control valve and calibration part to obtain the real-time leak rate; If the leak rate is higher than the threshold, trigger the helium purging function, and fill the vacuum chamber and pipeline with high-purity nitrogen to remove contamination; The recovery rate is controlled by the compressor and pump set to be not less than the preset ratio; Set multiple groups of parameters through the touch screen and display the qualified and unqualified results in real time. The system has password protection and fault records.

7. The vacuum chamber helium leak detection method as described in claim 4, characterized in that, The helium in the recovery tank is compressed to the high-pressure gas storage tank by the compressor, including: Obtain the helium in the low-pressure recovery tank and compress it through the compressor. The high-pressure gas storage tank is equipped with a pressure sensor; If the concentration is lower than the preset value, supplement helium from an external source, and control the process through solenoid valves and vacuum valves; Process helium through a precision filter to prevent impurities from contaminating the workpiece to be inspected; The PLC coordinates the electrical control part to achieve interlock protection. If the protection device operates, stop the operation and alarm; The touch screen displays the data statistics and the pressure change record. The system automatically stores the detection process data.

8. The vacuum chamber helium leak detection method as described in claim 1, characterized in that, The detection process is fully automated through PLC control and touch screen operation, including: Integrate system components through the communication module to achieve coordinated control; Set operation parameters such as leak rate and detection time, and prevent modification through password protection; If a fault occurs, record the time and alarm, including overload protection and overvoltage protection; Prompt qualified and unqualified through an audible and visual alarm, and ensure safety configurations such as an emergency stop switch.

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