最新刊期
期 9 ， 2022
- 摘要：Since 2021, the development concept of green manufacturing has been mentioned again in the 14th Five-Year Plan, and promoting green and low-carbon has become the strongest voice in today's society. Welding as a key link in the modern manufacturing industry, its pollution is very serious. Therefore, it is the general trend of striving to build an efficient, clean, low-carbon and circular green manufacturing system. As one of the most important brazing materials, the flux-cored brazing filler metal has the advantages of good comprehensive performance, low cost, good brazing fluidity, energy conservation and emission reduction, and a low degree of environmental pollution. It can be used for joining various dissimilar alloys and is widely used in refrigeration, machinery, electronics and other manufacturing fields, and has received a lot of attention at home and abroad. The several types of flux-cored brazing filler metals that have received widespread attention in recent years are discussed, and their research progress at home and abroad are elaborated, and the influence of the welding parameters on the microstructure and properties of the joints are also discussed. Finally the problems and difficulties in the preparation and brazing process of the current flux-cored brazing filler metals are sorted out, and the prospect of future development is put forward.关键词：flux-cored brazing filler metal;flux-cored zinc aluminum brazing filler metal;flux-cored silver brazing filler metal;green emission reduction
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发布时间：2022-09-28 - 摘要：7N01 aluminum alloy is a high-strength Al-Zn-Mg alloy with the advantages of heat-treatable strengthening, strong weldability, good processability and light weight. It has been widely used in high-speed trains, marine ships, aerospace and other fields. Since the 7N01 aluminum alloy welded joint has experienced the process of non-uniform heating and cooling,and the local microstructure of the welded joint has undergone complex changes. The precipitated phase has unbalanced dissolution and precipitation behavior, and is redistributed to the boundary and grain boundary, resulting in different components and structures in different regions of the welded joint, thus showing different corrosion sensitivity. A series of factors, such as aging process, post weld treatment and welding process parameters, will affect the corrosion resistance of 7N01 aluminum alloy welded joints. The complexity of service environment also brings great challenges to the research on corrosion behavior of 7N01 aluminum alloy.The corrosion types, research methods and occurrence areas of 7N01 aluminum alloy welded joints are reviewed. Meanwhile, the mechanism and influencing factors of corrosion resistance are analyzed, and the main ways to improve the corrosion resistance of the joints are proposed.关键词：7N01 aluminum alloy;welded joint;corrosion;research progress
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发布时间：2022-09-28 - 摘要：The preparation of kitchen knives and scissors is generally produced by the combination of traditional stamping, forging and heat treatment. Due to the limitations of traditional stainless steel materials, the performance of the knife and scissors blade is constrained. It is very rare to use laser processing technology to prepare high-performance blade coatings in the field of cutting tools. This paper describes in detail the traditional preparation methods of cutting tools and the existing laser preparation technology, in order to provide a reference for the rapid development of high-end cutting tool industry and the industrialization of laser processing technology. Firstly, the development status of cutting technology at home and abroad is introduced. Secondly, the bottleneck of domestic knife shear development is introduced from four aspects: materials, heat treatment, preparation process and technological innovation. Thirdly, combined with the current development of laser technology, several laser processing technologies that help the preparation and intelligent production of high-end cutting tools are introduced. Finally, some feasible suggestions are put forward for the establishment of future intelligent production line in the knife and shear industry.关键词：laser processing;knife and scissors;laser cladding;research progress
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发布时间：2022-09-28 - 摘要：Aiming at the problem of initial position of butt narrow gap weld, a local identification method based on edge matching for initial position of narrow gap weld was proposed in this paper. It can realize the recognition of initial weld points under complex light source environment. In this method, the image template technology is used to lock the local area of the initial weld point, and then the initial weld point recognition is completed before welding. Firstly, the weld image edges are selected as matching features, and a method based on Hough linear transform distance is proposed to remove noise to solve the problem of false edge caused by noise in edge dectetion. After image matching, the region containing the initial point of the weld can be obtained initially. Finally, Harris corner detection algorithm is combined with sub-pixel corner detection, and the selection rules are used to screen and accurately locate the sub-pixel initial point of the weld. Through the recognition of initial weld points in three different ambient light images, the comparison results show that the initial point recognition method proposed in this paper can accurately identify the initial weld points under the condition of uneven or insufficient illumination of the image, and has a certain anti-interference ability, laying a good foundation for the next step of weld tracking.关键词：initial welding position;image matching;corner detection;narrow gap weld;precise identification
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发布时间：2022-09-28 - 摘要：To ensure the validity of tensile shear test results of resistance spot welding joints, this paperanalyze the factors affecting the results of tensile shear test,Select 301 stainless steel, carbon steel, 5083 aluminum alloy resistance spot welding samples. Conduct a series of verification tests for the material, plate thickness, sample size, welding spot diameter, test rate, test temperature and other parameters. The Digital Image Correlation (DIC) techniquewas used to collect data for the test process. According to the test data, the tensile rate is less than 10mm/min and has little influence on the test results. Ambient temperature has an obvious effect on the test results, so the range of room temperature should be strictly required. It is recommended that the ambient temperature of the test be 23℃±5℃. Based on the strain field analysis obtained by DIC equipment, it is concluded that the reason for saturation strength condition is that the base metal part participates in the whole tensile shear process, and the maximum tensile shear force under saturation strength condition can be obtained when a complete annular strain region is formed around the welding spot.关键词：resistance welding;tensile shear;saturated strength condition;digital image correlation (DIC)
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发布时间：2022-09-28
Important Issuse
- 摘要：The cold metal transfer welding technology is used to weld 5083 aluminum alloy. The effect of pulse gas metal arc welding, direct-current/variable polarity cold metal transfer welding and direct-current/variable polarity cold metal mix with pulse transfer welding on weld forming are analyzed. By setting different AC balance, the influence of different positive/negative ratio and pulse ration on plate weld forming is analyzed. Butt welding tests of 8mm thick 5083 aluminum alloy are carried out by cold metal transfer welding, cold metal transfer mix with pulse transfer welding, variable polarity cold metal transfer welding and variable polarity cold metal transfer mix with pulse transfer welding. The weld forming, section appearance, micro blowhole number, microstructure and mechanical properties of different technologies are compared. The results show that the weld obtained by the cold metal transfer mix with pulse transfer welding is well formed with the lowest number of micro blowhole and slightly better mechanical properties. The microstructure of the weld is α phase (Al), granular precipitated phase and dispersion phase.关键词：cold metal transfer welding;variable polarity cold metal transfer welding;variable polarity cold metal mix with pulse transfer welding;weld forming;micro blowhole
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发布时间：2022-09-28 - 摘要：Narrow-gap laser filler wire welding is a new welding technology with high quality and high efficiency for thick wall components. Because of its small heat input, high energy density, fast welding speed, narrow heat affected zone, small welding deformation and high joint quality, laser-multi-pass narrow-gap has become a key technology in the manufacture of large thickness titanium alloy structural parts, which has attracted wide attention of scholars at home and abroad. However, due to the lack of relevant standards, it is unable to better promote the application of the technology in a wide range. Therefore, the formulation of “Recommended Process Specification for Narrow Gap Laser Filling Welding of Large Thickness Titanium Alloy ” is helpful to promote the development of laser-multi-pass narrow-gap of Large thickness titanium alloy in China and provide the basis for the construction of evaluation standard system of laser-multi-pass narrow-gap in China. In order to further facilitate relevant users to interpret the standard, this paper introduces some examples and related research results to explain the standard, so as to better interpret the standard.关键词：titanium alloy;large thickness;laser-multi-pass narrow-gap;group standard
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发布时间：2022-09-28 -
Influence of Ni/Au Plating Process and Plating Thickness of Kovar Alloy on Laser Seal Welding Cracks
摘要：The Kovar alloy with Ni/Au plating as a protective layer and brazing layer is used as the metal shell for the gas tight package of microwave assembly. The LW600AE laser is used to conduct the laser seal welding of the shell and cover plate of Kovar alloy with Ni/Au plating to obtain the welded joints with beautiful appearance and qualified air tightness, and the influence of the Ni/Au plating process and plating thickness on the cracks of welded joints are analyzed. The results show that the P element in electroless plating Ni finish and Au element in electroplating Au finish have lower melting points compared to other elements in Kovar alloy, and are very easy vaporized to form a variety of low melting point eutectic, which causes cracks. When the thickness of Au finish on the surface of Kovar alloy with electroplating Ni and Au is less than 0.8μm, no cracks occur. As the thickness of Au finish increases, a large amount of Au elements integrate into the weld, the tendency and length of cracks in welding joints improve. The increase of electroplating Ni finish does not lead to crack generation. When the electroplating Ni finish is 8~11 um, electroplating Au finish is 0.1~0.3um, the quality of welded joint of microwave assembly is good, and better protection and brazing properties are obtained.关键词：kovar alloy;Ni/Au finshes;laser seal welding;cracks;plating process- 50
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发布时间：2022-09-28 - 摘要：In order to solve the problem of heavy workload, high labor intensity and resource consumption caused by traditional welding process manufacturing for the ball valve of the large pumped storage unit, by combining narrow gap GMAW technology with robot welding technology, the key technologies are studied, including welding process structure design and deformation control of ball valve body, robot narrow gap transverse welding process, welding quality process control. The narrow gap welding groove of ball valve body suitable for robot welding is designed, and through small sample test, the key parameters of swing arc narrow gap GMAW are analyzed and proved, and welding parameters ranges are determined. Combining with the welding and manufacturing of ball valve body of pumped storage group, the reasonable reverse deformation is set, the welding quality control measures are laid down, and a new manufacturing technology of robot narrow gap transverse welding for large ball valve body is developed. This new technology has been applied to a ball valve of a pumped storage product. The welds of this product are tested by UT and TOFD flaw detection, and the pass rate is over 99%. The results show that this technology is feasible, which realizes the stable and efficient welding, reduces the labor intensity of workers, and achieves the effect of energy saving and emission reduction.关键词：ball value manufacturing;Robot welding;narrow gap;welding quality;welding deformation
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发布时间：2022-09-28 - 摘要：During the regular inspection of spherical tanks in a large chemical enterprise, there are a lot of weld cracks on the internal and external surfaces of the 3 000 m³ propylene spherical tank. The cracks are found classified and counted according to the location and category, and the appearance of typical crack defects are analyzed. The causes of weld cracks are analyzed in depth, and the five major causes of weld cracks on the spherical tank are summarized, The targeted treatment suggestions, precautions for the construction, installation and regular inspection of spherical tanks in the future and preventive measures to avoid weld crack are given. The results show that poor welding technology, on-site heat treatment not meeting the specification requirements, and welding residual stress are the main causes of spherical tank cracking. During the manufacturing process of spherical tank, the quality of raw materials and manufacturing quality of spherical shell plate shall be strictly controlled, and the quality of welding process and non-destructive testing of welds after welding shall be controlled. In the regular inspection process, the upper and lower circumferential welds shall be focused on. The method of UT+TOFD can be used for weld testing.关键词：spherical tank;butt weld;crack;periodic inspection;upper and lower circumferential welds
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发布时间：2022-09-28 - 摘要：Repairing the composite metal layer of bearing bush of large rotating equipment by online repair welding is a least costly repair method. However, the welding can only be carried out in horizontal position because of the heavy bearing, the difficulty of adjusting the bearing Angle, the low melting point of composite metal and the easy flow of liquid. These difficulties limit the implementation of online repair work and form the difficult problem of repairing bearing bush defects. For repair welding only horizontal position welding, as well as the bearing rotation fixed is difficult,the professional equipment for adjusting the bearing bush welding and repair posture has been innovated, and the tools for reducing the adverse factors of the formation of wear-resistant alloy liquid welds have been developed. For poor fusion of dissimilar metal welding between bearing base metal and wear-resistant layer alloy, using the shallow penetration, easy operating method of fusion. This series of improvement measures can effectively overcome the difficulties through practice, so that online comprehensive high quality and efficient welding repair damaged wear-resistant alloy layer work can be implemented smoothly.关键词：online welding;composite metal;bearing bush;innovation
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发布时间：2022-09-28 - 摘要：For the welding of super duplex stainless steel pipeline in a 1 500 m subsea manifold project, the control system Tubings in the pipeline are small-diameter tube with diameter of less than 1 inch, which requires welder's welding skill level extremely high, and the risk of root blockage is easy to be formed by manual argon tungsten arc welding for backing weld. The company adopts the welding method of autogenous welding or autogenous + manual filler wire welding, which is applied in the production of the project. The forming of the root of bead is excellent, the good backing welds are obtained in batches, and the welding effect is ideal. Since autogenous welding requires high ellipticity of base metal and accuracy of weld assembly, combining with the welding difficulties in the production process of the project, in-depth analysis are made and effective solutions are taken. Through several production projects in the past few years, the most frequent welding defects are summarized, the error correction schemes in production are followed, and experience and lessons in production are summarized, which provides a good reference for subsequent project production.关键词：super duplex stainless steel;autogenous welding;welding defects;welding method
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发布时间：2022-09-28
Welding Technology
- 摘要：A method based on photoelectric detection has been proposed to measure manual welding speed, coupled with welding voltage and current, the online datection of welding heat input during manual welding process is realized. This method is applied to the online detection of welding heat input in various positions and various manual open arc welding methods. A kind of arc capture mechanism and combination method is designed to convert the moving speed of arc light into pulse signal and calculate the welding speed by controller. A test platform based on STM32 is built to complete digital detection, display and data management of welding heat input. The experiment shows that the method is good at real time and the data fluctuation range is small, so that the detection precision of welding heat input is improved.关键词：welding heat put;on-line detection;speed sensor;arc light capture mechanism
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发布时间：2022-09-28 - 摘要：In order to provide customers with more rapid and high-quality equipment, standardized design was carried out according to the type and structure of the company's commonly used positives to form the company's standard equipment, which greatly shortened the production time of the company's entire project, improved work efficiency, and provided the welding workstation to customers more quickly. At present, welding positioner has become an indispensable part of welding robot workstation. This paper introduces the typical application examples of the three-axis vertical overturning positioner in the robot welding workstation, the main technical parameters of the standard positioner, the working principle, structure design and drive selection of the three-axis vertical overturning positioner. The idea of modularization is carried out to the whole design process of the positioner. The structure of the three-axis vertical turning positioner is divided into: driving unit, driven unit, rotating frame, base, head box, tail box and other modules. Each module has a unified installation size, but each module has a different structure size, so after combination, design a variety of types, meet the needs of a variety of welding fixtures, adapt to a wider range of robot welding workstations.关键词：robot welding workstation;three-axis vertical turning positioner;load calculation;modular structure design
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发布时间：2022-09-28
Welding Equipment
- 摘要：In view of the fact that the welding of 690 MPa grade building structural steel mainly adopts imported electrodes, the localization of J807GD electrode has been studied. By adding different kinds of fluoride into the coating in proportion, the fluidity of the slag is optimized, and some powders with crystal water in the coating are pre baked to reduce the diffusible hydrogen content in the weld, strictly control the content of Mn, Cr, Cu and other elements in the weld, and optimize the yield ratio of the deposited metal. The results show that the developed J807GD electrode has excellent horizontal and vertical welding processability, the yield ratio ≤0.92, and the mechanical properties meet the technical requirements under the recommended parameters. The welding parameters are applicable to a wide range, which are suitable for the welding of690 MPa grade building structural steel, and can meet the technical requirements of engineering applications. This study solves the problem of the balance between the high yield ratio and impact toughness of deposited metal of supporting electrodes for 690 MPa grade building structural steel, and provides a theoretical basis for the research on the localization of supporting electrodes for 690 MPa grade building structural steel.关键词：J807GD electrode;high strength and high toughness;yield ratio;690 MPa grade building structural steel
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发布时间：2022-09-28 - 摘要：Low alloy steel 16MND5 for pressure vessel of domestic nuclear power reactor type "HPR1000" reactor has been developed domestically with manual welding electrode. Electrode welding process has long relied on the experience of welding workers, and it is difficult to scientifically and quantitatively determine the advantages and disadvantages of electrode welding process performance. Through the research on the quantitative evaluation method of process performance index, the comparison and quantitative evaluation of process performance between newly developed domestic electrodes and imported welding materials are carried out, and the factors affecting the stability of welding process are summarized and studied, such as arc stability For slag removal and forming appearance, the process performance indexes of welding materials are scientifically evaluated by quantitative method. From the evaluation results, the existing quantitative evaluation standards and methods of process performance can scientifically evaluate the welding process performance of welding electrodes. Compared with the evaluation results, the process performance of domestic manual welding electrodes is equivalent to that of imported welding materials, reaching the research goal of the subject project. Through quantitative evaluation, it is proved that domestic welding materials have realized the transformation from "usable" to "easy to use".关键词：reactor pressure vessel;low-alloy steel 16MND5;welding rod;process quantification
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发布时间：2022-09-28
Welding Material
- 摘要：As an important part of practical teaching in colleges and universities, mechanical manufacturing practice is of great significance to cultivate students' engineering practice ability and improve their engineering quality. In recent years, Tsinghua university basic industry training center (hereinafter referred to as "the Center") has made great adjustments in the improvement of practical teaching concepts and teaching conditions, and relying on various kinds of funds and abilities, the laboratory construction of the center has made great progress. In order to improve the quality of personnel training, the planning and construction of the practical teaching platform for forming manufacturing are comprehensively studied. From the major aspects of the function orientation and construction principle, resource construction and teaching construction of the practice teaching platform for forming manufacturing, through the platform hardware and software construction, teaching team composition, platform management and practical teaching course development, the concrete measures of laboratory in platform construction in recent years are systematically expound. It is found that the construction of practical teaching platform must be in line with the objectives of talent training and subject development strategy of colleges and universities and current social development situation. Meanwhile, by exploring the connotation of teaching projects and sorting out the new teaching mode of engineering training based on forming manufacturing, the talent training of practical courses is carried out better and the quality of talent training is further improved.关键词：forming manufacturing practice;practice platform;construction and planning;quality of personnel training
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发布时间：2022-09-28 - 摘要：In order to thoroughly implement the spirit of the National Vocational Education Conference, explore the comprehensive education model of "post class competition certificate". Combined with the current curriculum setting of intelligent welding technology, there are problems of low degree of fit in meeting job ability requirements, skill competitions, and vocational skill level verification, which further limits the improvement of students' professional ability and restricts the training of high-skilled talents by vocational education. quality. This paper constructs a professional curriculum system of intelligent welding technology from the "post ability-course-skill competition-vocational skill level certificate" integrated mode, in order to achieve the goal of professional talent training.关键词：post-class competition certificate;intelligent welding technology;curriculum system;personnel training
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发布时间：2022-09-28
Welding Education
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