The frontiers of quality control technology development are highlighted in the following four aspects:
(1) Quality online control technology
Temperature, time and furnace gas composition are the most basic control parameters in the online control technology of heat treatment quality. In terms of temperature control, thyristor temperature control technology has been widely used at home and abroad. Combined with PID instrumentation, the temperature of the hot process can be controlled to a fairly precise range. For the heat treatment and forging heating process of large parts and large furnaces, special instruments, programmable controllers, microprocessors, etc. have been used in the vacuum heating of the whole furnace workpiece to achieve the temperature change law according to the process requirements (heating speed, The heating step, the holding time, the cooling rate with the furnace, the air cooling rate, etc. are applied to perform heating and cooling, and the temperature can be tracked from the beginning to the end of the process. In terms of furnace gas control, from the perspective of sensors, we have experienced the development of a dew point method, the infrared detector, the oxygen probe. At present, carburizing in an endothermic atmosphere, a nitrogen-based synthetic atmosphere and a drip-type atmosphere, using an oxygen probe as a sensor, the carbon potential of the furnace gas can be made under the premise of strictly controlling the furnace temperature and the good pen circulation of the furnace gas (carbon surface of the steel) The amount) is accurate to ±0.05 to 0.02%. By using the microprocessor to accurately control the temperature, furnace carbon potential, strong seepage and diffusion time, the on-line control of the surface carbon content, the depth of the layer, and the carbon concentration gradient of the layer are distributed according to certain rules.
For the on-line control technology of heat treatment quality, it is urgent to consider the direct control of the carbon potential during the recent atmosphere carburizing, and the carbon concentration distribution of the workpiece surface during the methanol-hydrogen-acetone (kerosene) synthesis atmosphere carburizing. Adapt to control, online control of forging heat quenching line temperature, on-line monitoring of forging die and stamping die wear.
(2) Non-destructive testing and evaluation technology
100% non-destructive testing of part quality and internal defects is one of the development trends of quality control in advanced manufacturing technology. Advances in physics such as electricity, magnetism, sound and light have greatly promoted non-destructive testing technology, The rapid development of aerospace, nuclear power and other industries has led to a leap in non-destructive testing technology. In the non-destructive testing technology, in addition to the commonly used methods of radiation, ultrasonic, magnetic, electromagnetic induction (eddy current), infiltration (fluorescence, coloring), etc., the emerging non-destructive testing techniques include electron transmission photography, high-energy X-ray method, and ray layer. Analytical method, optical holography, ultrasonic holography, infrared test, microwave test, etc. Non-destructive testing methods for material and part properties include residual magnetic method, coercive force method, eddy current method, magnetic noise method (Buckson effect method), higher harmonic method, ultrasonic scattering echo method and acoustic emission method.
Foreign countries pay great attention to the application of online non-destructive testing. For example, the eddy current testing method for inspecting defects on the surface of pipes, profiles and surfaces is an example. The FORSTER Research Institute of Germany has developed an automatic detection system for edging of Φ2～30mm tube sheets. The highest detection speed reaches 4m/ s, the maximum sensitivity is 30 μm. The institute has also developed a series of rotary and penetrating probes, and the serialization and industrialization technologies are quite mature. In the past 20 years, many technologies and equipments including traditional eddy current testing systems, far-field eddy currents, seepage eddy currents, multi-frequency eddy currents, and pre-multi-frequency eddy currents have been introduced. Many units have developed such technologies themselves, but The maturity is not high, and the introduction of equipment is not good, and most of them cannot be operated normally on the production line.
In the forefront of non-destructive testing, there are urgent need to solve the multi-dimensional eddy current testing methods and equipment for ferromagnetic tubes, rods, and filament materials, and non-destructive testing methods and equipment for induction heating surface hardened layers and carburized hardened layers. On-line non-destructive testing method and equipment for mass production of heat-treated parts after heat treatment, real-time detection of defect image processing and display in thick-walled container welding process, mass production of ball-and-iron iron parts ball ratio and online non-destructive testing system for matrix structure, high-resolution X-ray Online non-destructive testing systems, etc.
(3) Statistical Process Control (SPC) Technology
Statistical Process Control (SPC) technology is a modern quality management technology that integrates production technology and scientific management. In this direction, it belongs to cutting-edge technologies: SPC quality control of carburizing and quenching, precision forming (die casting, precision forging, etc.) SPC quality control. And SPC quality control of heat treatment distortion.
The human production process has undergone the following seven steps to control product quality: 1 to investigate the final quality of the product; 2 to analyze the individual factors that significantly affect the quality; 3 to control the changes of these factors by manual adjustment; 4 to automatically control these influencing factors; 5 Use statistical methods to obtain the law of continuous change of production effect; 6 comprehensively investigate and understand other secondary factors affecting quality; 7 consider all factors, establish a complete theoretical model to control the entire production process, and obtain 100% qualified products. At present, many industrial advanced countries in the world have begun to test the seventh step of SPC production. It is reported that SPC technology has produced outstanding effects in heat treatment production. FORD, DONA, and BLANDBURGH NENO heat treatment plants in the United States are studying the quality control of SPC technology for heat treatment. In the United States PENNSYLVANIA METALLURGICAL company in the 1018 steel carbonitriding process, 25% of the workpieces exceeded the upper limit of the required depth (0.46MM), 0.83% of the workpiece did not reach the lower limit of the layer (0.20MM), through statistical process analysis, improvement The process adopted measures such as shortening the co-infiltration time, reducing the carbon potential of the furnace gas, improving the basket, and improving the circulation of the furnace gas. Finally, the workpiece exceeding the upper limit was reduced to 2.9%, and the workpiece below the lower limit was 0.01%.
The quality control process of forming and modified production in China is currently limited to the first to third steps. Individual enterprises have realized the automatic control of individual influencing factors. The system research and development and application of SPC technology are still unknown.
(4) Precision sensing technology
The most common type of temperature sensor used in mechanical manufacturing hot forming and modification technology is the temperature measuring element that works in high temperature, special atmosphere, special liquid, such as high temperature reducing and osmosis. A thermocouple with a carbon atmosphere, high temperature and high vacuum, high temperature liquid metal, and molten salt for long-term operation. Secondly, the zirconia oxygen concentration battery (oxygen probe) with high precision and long life, which can measure the trace oxygen and carbon potential of the furnace gas, and the slight change of the electromagnetic properties of the sensing material, thereby measuring the change of material properties (hardness, strength, tissue defect) Electromagnetic sensor and display instrument. There are also probes that emit ultra-high-frequency sound waves and have high sensitivity to receive back-scattered sound waves. They sense the cooling intensity of quenching medium, gas-liquid flow rate, pressure, and corrective pressure.
In the 1990s, silicon-based substrates, micro-machining technology manufacturing of various sensors developed the fastest, optical and solid-state sensors using microprocessor technology has also been widely used, sensor and actuator integration is the focus of the future The direction of development, smaller size, cheaper price and more reliable performance are the main trends in sensor development.
Since the 1980s, the development and production of sensitive components and sensors in China have formed an industry. In 1990, the output value has reached 770 million yuan, high temperature thermocouples, oxygen probes, heat sensitive, photosensitive, gas sensitive, humidity sensitive, pneumatic components, etc. Domestically, we have mastered manufacturing and have product supply. However, the sensitivity of these domestic sensors is generally low, especially the poor reliability, low service life, some sensors are incomplete, can not meet the production needs, compared with advanced industrial countries, there is still a gap of 10 to 20 years.
(1) Quality online control technology
Temperature, time and furnace gas composition are the most basic control parameters in the online control technology of heat treatment quality. In terms of temperature control, thyristor temperature control technology has been widely used at home and abroad. Combined with PID instrumentation, the temperature of the hot process can be controlled to a fairly precise range. For the heat treatment and forging heating process of large parts and large furnaces, special instruments, programmable controllers, microprocessors, etc. have been used in the vacuum heating of the whole furnace workpiece to achieve the temperature change law according to the process requirements (heating speed, The heating step, the holding time, the cooling rate with the furnace, the air cooling rate, etc. are applied to perform heating and cooling, and the temperature can be tracked from the beginning to the end of the process. In terms of furnace gas control, from the perspective of sensors, we have experienced the development of a dew point method, the infrared detector, the oxygen probe. At present, carburizing in an endothermic atmosphere, a nitrogen-based synthetic atmosphere and a drip-type atmosphere, using an oxygen probe as a sensor, the carbon potential of the furnace gas can be made under the premise of strictly controlling the furnace temperature and the good pen circulation of the furnace gas (carbon surface of the steel) The amount) is accurate to ±0.05 to 0.02%. By using the microprocessor to accurately control the temperature, furnace carbon potential, strong seepage and diffusion time, the on-line control of the surface carbon content, the depth of the layer, and the carbon concentration gradient of the layer are distributed according to certain rules.
For the on-line control technology of heat treatment quality, it is urgent to consider the direct control of the carbon potential during the recent atmosphere carburizing, and the carbon concentration distribution of the workpiece surface during the methanol-hydrogen-acetone (kerosene) synthesis atmosphere carburizing. Adapt to control, online control of forging heat quenching line temperature, on-line monitoring of forging die and stamping die wear.
(2) Non-destructive testing and evaluation technology
100% non-destructive testing of part quality and internal defects is one of the development trends of quality control in advanced manufacturing technology. Advances in physics such as electricity, magnetism, sound and light have greatly promoted non-destructive testing technology, The rapid development of aerospace, nuclear power and other industries has led to a leap in non-destructive testing technology. In the non-destructive testing technology, in addition to the commonly used methods of radiation, ultrasonic, magnetic, electromagnetic induction (eddy current), infiltration (fluorescence, coloring), etc., the emerging non-destructive testing techniques include electron transmission photography, high-energy X-ray method, and ray layer. Analytical method, optical holography, ultrasonic holography, infrared test, microwave test, etc. Non-destructive testing methods for material and part properties include residual magnetic method, coercive force method, eddy current method, magnetic noise method (Buckson effect method), higher harmonic method, ultrasonic scattering echo method and acoustic emission method.
Foreign countries pay great attention to the application of online non-destructive testing. For example, the eddy current testing method for inspecting defects on the surface of pipes, profiles and surfaces is an example. The FORSTER Research Institute of Germany has developed an automatic detection system for edging of Φ2～30mm tube sheets. The highest detection speed reaches 4m/ s, the maximum sensitivity is 30 μm. The institute has also developed a series of rotary and penetrating probes, and the serialization and industrialization technologies are quite mature. In the past 20 years, many technologies and equipments including traditional eddy current testing systems, far-field eddy currents, seepage eddy currents, multi-frequency eddy currents, and pre-multi-frequency eddy currents have been introduced. Many units have developed such technologies themselves, but The maturity is not high, and the introduction of equipment is not good, and most of them cannot be operated normally on the production line.
In the forefront of non-destructive testing, there are urgent need to solve the multi-dimensional eddy current testing methods and equipment for ferromagnetic tubes, rods, and filament materials, and non-destructive testing methods and equipment for induction heating surface hardened layers and carburized hardened layers. On-line non-destructive testing method and equipment for mass production of heat-treated parts after heat treatment, real-time detection of defect image processing and display in thick-walled container welding process, mass production of ball-and-iron iron parts ball ratio and online non-destructive testing system for matrix structure, high-resolution X-ray Online non-destructive testing systems, etc.
(3) Statistical Process Control (SPC) Technology
Statistical Process Control (SPC) technology is a modern quality management technology that integrates production technology and scientific management. In this direction, it belongs to cutting-edge technologies: SPC quality control of carburizing and quenching, precision forming (die casting, precision forging, etc.) SPC quality control. And SPC quality control of heat treatment distortion.
The human production process has undergone the following seven steps to control product quality: 1 to investigate the final quality of the product; 2 to analyze the individual factors that significantly affect the quality; 3 to control the changes of these factors by manual adjustment; 4 to automatically control these influencing factors; 5 Use statistical methods to obtain the law of continuous change of production effect; 6 comprehensively investigate and understand other secondary factors affecting quality; 7 consider all factors, establish a complete theoretical model to control the entire production process, and obtain 100% qualified products. At present, many industrial advanced countries in the world have begun to test the seventh step of SPC production. It is reported that SPC technology has produced outstanding effects in heat treatment production. FORD, DONA, and BLANDBURGH NENO heat treatment plants in the United States are studying the quality control of SPC technology for heat treatment. In the United States PENNSYLVANIA METALLURGICAL company in the 1018 steel carbonitriding process, 25% of the workpieces exceeded the upper limit of the required depth (0.46MM), 0.83% of the workpiece did not reach the lower limit of the layer (0.20MM), through statistical process analysis, improvement The process adopted measures such as shortening the co-infiltration time, reducing the carbon potential of the furnace gas, improving the basket, and improving the circulation of the furnace gas. Finally, the workpiece exceeding the upper limit was reduced to 2.9%, and the workpiece below the lower limit was 0.01%.
The quality control process of forming and modified production in China is currently limited to the first to third steps. Individual enterprises have realized the automatic control of individual influencing factors. The system research and development and application of SPC technology are still unknown.
(4) Precision sensing technology
The most common type of temperature sensor used in mechanical manufacturing hot forming and modification technology is the temperature measuring element that works in high temperature, special atmosphere, special liquid, such as high temperature reducing and osmosis. A thermocouple with a carbon atmosphere, high temperature and high vacuum, high temperature liquid metal, and molten salt for long-term operation. Secondly, the zirconia oxygen concentration battery (oxygen probe) with high precision and long life, which can measure the trace oxygen and carbon potential of the furnace gas, and the slight change of the electromagnetic properties of the sensing material, thereby measuring the change of material properties (hardness, strength, tissue defect) Electromagnetic sensor and display instrument. There are also probes that emit ultra-high-frequency sound waves and have high sensitivity to receive back-scattered sound waves. They sense the cooling intensity of quenching medium, gas-liquid flow rate, pressure, and corrective pressure.
In the 1990s, silicon-based substrates, micro-machining technology manufacturing of various sensors developed the fastest, optical and solid-state sensors using microprocessor technology has also been widely used, sensor and actuator integration is the focus of the future The direction of development, smaller size, cheaper price and more reliable performance are the main trends in sensor development.
Since the 1980s, the development and production of sensitive components and sensors in China have formed an industry. In 1990, the output value has reached 770 million yuan, high temperature thermocouples, oxygen probes, heat sensitive, photosensitive, gas sensitive, humidity sensitive, pneumatic components, etc. Domestically, we have mastered manufacturing and have product supply. However, the sensitivity of these domestic sensors is generally low, especially the poor reliability, low service life, some sensors are incomplete, can not meet the production needs, compared with advanced industrial countries, there is still a gap of 10 to 20 years.
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