Research and prospect of ultrasonic welding technology
Abstract: Ultrasonic welding has outstanding advantages such as energy saving, environmental protection and convenient operation, which has attracted more and more attention. Ultrasonic welding has been widely used in many fields. The basic principle of ultrasonic welding is briefly introduced. The development of ultrasonic welding in China is summarized, and the development of ultrasonic welding is prospected.
Keywords: research status of ultrasonic welding
Introduction to 0
1950, Americans invented ultrasonic welding technology, which is widely used in industrial production as a special connection technology. In addition, ultrasonic welding technology is also widely used in electronics industry, electrical appliance manufacturing, new materials and equipment, aerospace and nuclear energy industries, food packaging boxes, advanced parts sealing technology and so on. The advantages of ultrasonic welding are energy saving, environmental protection and convenient operation. This technology has greatly promoted the construction of a resource-saving and environment-friendly society in China.
1 Principle and characteristics of ultrasonic welding [1]
As a special welding method, ultrasonic welding usually refers to the use of mechanical vibration energy with ultrasonic frequency (greater than 16KHZ) to connect the same or different metals, semiconductors, plastics and cermets. When welding metal by ultrasonic wave, on the one hand, there is no need to apply current to the workpiece, on the other hand, there will be no high-temperature heat source introduced into the workpiece. In the welding process, under the action of static pressure, elastic vibration energy is converted into friction work, deformation energy and limited temperature rise between workpieces. Under the condition that the base metal does not melt, the metallurgical bonding between joints is realized, so ultrasonic welding belongs to solid-state welding.
Under the action of the ultrasonic generator, the power frequency current is further converted into an oscillation current with the ultrasonic frequency of (15 ~ 16 kHz) d, and the transducer converts electromagnetic energy into elastic mechanical vibration energy through magnetostrictive effect. The function of the amplifier is to amplify the amplitude, and at the same time, it is coupled with the workpiece through the coupling rod and the upper acoustic electrode. If the natural frequencies of the transducer, amplifier, coupling rod and upper sonotrode are consistent with each other, in this case, the system will resonate, thus transferring elastic vibration energy to the workpiece with static pressure F, and the two thin workpieces are bonded together through this energy conversion.
2 domestic research status
2. 1 research status of ultrasonic metal welding
Cui Yan [2] studied the application of ultrasonic welding in the welding repair of tank aluminum parts, and made a detailed analysis of the weldability of aluminum and aluminum alloys. He believes that the accuracy of resonant frequency is an important factor to ensure the stability of solder joint quality. In the process of ultrasonic welding, due to the variable mechanical load, detuning will occur randomly, which will make the quality of solder joints unstable. According to the characteristics of ultrasonic welding, the corresponding welding specifications are formulated. A large number of experiments have proved that ultrasonic welding of aluminum and aluminum alloy can effectively remove the dense oxide film on the metal surface, thus ensuring the welding quality.
Yang Shengwen of South China University of Technology and others [3] deduced the theoretical regional temperature formula of ultrasonic welding joint of copper sheet-copper tube solar collector, and measured the welding regional temperature by artificial thermocouple method, analyzed the reasons for the measurement temperature deviation, and compared it with scanning electron microscope (SEW) pictures, and studied the formation mechanism of ultrasonic welding joint of copper sheet-copper tube. The results show that ultrasonic welding is a physical metallurgical process based on two factors: the high temperature of micro-tooth tip in the joint area and the complete adhesion of pure metal surface after plastic deformation.
Zhang [4] of the School of Mechanical and Electrical Engineering of Nanjing University of Aeronautics and Astronautics studied the solid-state diffusion welding process of 1Cr 18Ni9Ti and TC4 dissimilar metals, and adopted the ultrasonic loading solid-state diffusion welding process on the existing basis. The results of metallographic examination show that stainless steel and titanium have formed a good connection by ultrasonic loading diffusion welding process.
Yan Jiuchun, Sun et al of Harbin Institute of Technology [5]. A structure which is suitable for complex structures and can be reliably connected in an open environment is studied. Ultrasonic vibration assisted brazing technology? At the same time, the preliminary test results of aluminum matrix composites, aluminum alloys, ceramics/aluminum and glass/aluminum welding are introduced. The welding results show that proper ultrasonic vibration can effectively remove the oxide film on the surface of the base metal and further promote the wetting of the base metal and solder. The joints with good microstructure and mechanical properties were obtained in low temperature atmospheric environment.
Zhu et al. [6] of Nanchang University studied the microstructure changes of aluminum alloy AA606 1 under ultrasonic welding by electron backscatter diffraction (EBSD), which deepened the understanding of ultrasonic metal welding from the microscopic point of view. Through experiments, the distribution diagram of orientation difference between the original aluminum foil and the welded aluminum foil is obtained. By analyzing the grain orientation, grain structure and grain boundary characteristics, the influence of ultrasonic welding on the microstructure and structure of aluminum alloy is understood.
2.2 Research Status of Ultrasonic Non-metallic Welding
Guo Yufeng [7] 12? M polyethylene terephthalate (PET)/30? The ultrasonic welding process of M polyethylene (PE) film was studied. It was found that the welding amplitude was 2- 10? M has little effect on the heat sealing strength of welded joints; When the welding amplitude is 4-7? The maximum heat sealing strength of welded joints appears at m, and with the extension of welding time and the increase of welding pressure, the heat sealing strength of welded joints first increases and then decreases. By analyzing the crystallinity of the welding zone under different process parameters, the results show that the crystallinity of the joint affects the heat sealing strength of the welded joint of PET/PE film. With the increase of welding time, welding amplitude and welding pressure, the crystallinity of the welded joint sample first decreases and then increases, while the heat sealing strength of the welded joint first increases and then decreases.
Zhao Gang [8] and others studied the application of ultrasonic welding in automobile sensor packaging. Through the selection of materials and welding methods, the design of welding joints and tooling, and the design of manufacturing process, this paper expounds the methods for realizing the packaging of automobile sensors.
Zhao Shibin [9] studied the application of ultrasonic welding in connectors. This paper briefly introduces the principle of ultrasonic welding, the design method and key points of joint surface, and the specific application and scope of use in connector.
Nie Zhongming of Northwestern Polytechnical University [10] studied the ultrasonic welding of contact electrode and lead wire of high resistance CdZnTe semiconductor (CZT for short). It is considered that the ultrasonic bonding rate between the gold electrode prepared by ion sputtering and the external lead is high after the mechanical polishing surface treatment of CZT wafer, and the electrode thickness that can obtain the best solder joint quality is 180nm. In addition, after the preparation process of CZT contact electrode is determined, wedging pressure becomes the main factor affecting the quality of ultrasonic welding between CZT contact electrode and lead wire, and welding power is the secondary factor.
3 abstract
At present, the understanding of ultrasonic metal welding mechanism is insufficient. Is ultrasonic metal welding solid state welding or metal-to-metal welding? Whether there is a combination of metal melting in the welding process needs further study. In addition, although the application of ultrasonic in material welding has a good welding effect, there are still problems in stability, operability and reliability for the whole system composed of ultrasonic generator, acoustic system and mechanical system, so the design of acoustic system and the connection mode between acoustic system and specimen are very important. In addition, it is also an important direction to study the effect of ultrasonic vibration on grain and texture from the perspective of micromechanics.
References:
[1] Li Xiaoming, Li Yansheng, Han Jingyun. Research on rapid prototyping method based on ultrasonic welding technology [J]. Machine Tool and Hydraulic, 2007,35 (3): 4-6.
Cui Yan. Application of ultrasonic welding in maintenance of aluminum parts of storage tanks [J]. Industrial Technology and Economy, 2000,19 (3):114-16.
Yang Shengwen, Wu Zequn, Chen Pingchi. Experimental study on ultrasonic welding of copper sheet-copper tube solar collector [J]. Welding, 2005 (9): 32-35.
Zhang. Ultrasonic Diffusion Welding of Titanium and Stainless Steel [J]. Mechanical Engineering and Automation, 2008 (1):125-127.
Yan Jiuchun, Sun,. Ultrasonic vibration assisted brazing technology [J]. Welding, 2009 (3): 6- 12.
Zhu, Ma, Ye Haimei. Microstructure evolution analysis of aluminum alloy AA606 1 ultrasonic welding [A]. Proceedings of the 7th China robot welding academic and technical exchange conference [C], 2008:107-10.
Guo Yufeng. Ultrasonic welding of polyethylene terephthalate/polyethylene film [J]. Aerospace Materials Technology, 20 10 (4): 53-55.
Zhao Gang, Cao Zhi, Dong Shuanghui. Application of ultrasonic welding in automobile sensor packaging [J]. Journal of Shenyang Institute of Aeronautical Technology, 2007 (4): 25-28.
Zhao Shibin. Application of ultrasonic welding in connectors [J]. Electromechanical components, 2006 (4): 36-39.
Nie Zhongming, Liv, Vicki and Cha Gangqiang. Ultrasonic welding of CdZnTe contact electrode and lead [J]. Journal of China Nonferrous Metals Society, 2009, 19 (5): 9 19-923.
Application of ultrasonic welding technology in industrial product design
By expounding the principle of ultrasonic welding technology, this paper discusses the influencing factors of ultrasonic, and analyzes the advantages and disadvantages of ultrasonic welding technology. Based on the author's design practice, this paper discusses the development of ultrasonic welding technology and explores the future application fields based on ultrasonic welding technology.
Ultrasonic wave; Welding technology; industrial product
Application of ultrasonic welding technology in industrial product design? explore
He Jun-Hua 1- Juan 2- Shuang 3 Weng Mao-Hong 1 Guan Jun 1 Gong Yun 1
(1. College of Engineering, Zhejiang Agricultural University; F university, Lin? An Zhejiang, 3 1 1300, China;
2. College of Agriculture and Food Science, Zhejiang Agricultural University; F university, Lin? An Zhejiang, 3 1 1300, China;
3. School of Landscape Architecture and Architecture, Zhejiang Agricultural University; F university, Lin? An Zhejiang, 3 1 1300, China)
This paper expounds the principle of ultrasonic welding and the influencing factors of ultrasonic probe, and analyzes the advantages and disadvantages of ultrasonic welding technology in combination with the author's working practice. Combined with design practice, the development of ultrasonic welding technology is discussed, and the application prospect of ultrasonic welding technology is discussed on this basis.
Keywords ultrasound; Welding technology; industrial product
In the production of industrial products, some industrial materials are often used, such as plastics, metals, wood and other industrial materials. In daily life, we often see that a product is not made of only one material; We often see that a product is composed of multiple parts, and there will be gaps between the parts, which will not only affect the quality of the product, but also affect the beauty of the product. This requires welding them together. With the development of science and technology, people have higher and higher requirements for welding technology. At present, the traditional welding technology is not only high in cost, but also low in welding quality, and micro cracks often appear. Therefore, people hope to adopt new welding technology to improve product quality.
1943, American Behl invented ultrasonic welding on the basis of summarizing predecessors' theory and practice, which promoted the development of ultrasonic welding technology. Because ultrasonic welding technology has the advantages of energy saving, no need to assemble smoke suppression device and welding accessories, low cost, high efficiency, good sealing and easy to realize automatic production, ultrasonic welding technology is developing faster and faster.
1 application status of ultrasonic welding technology in industrial products
Such as aerospace, nuclear energy industry, electronic industry and other industrial products with high precision requirements, it is difficult to meet the technical requirements with traditional welding technology, with high cost and low efficiency. At present, ultrasonic welding technology is widely used in various industries, such as medical machinery, packaging, hardware and other industries; There are many products that can be welded, such as auto parts, optical lenses, USB flash drives and so on.
Principle and characteristics of ultrasonic welding technology
Ultrasonic wave is a kind of sound wave with frequency higher than 20000 Hz, so it has great energy. Ultrasonic welding is a special welding method that uses mechanical vibration energy with ultrasonic frequency (above 20000 Hz) to connect the same or different metals, semiconductors, plastics and cermets [1]. When ultrasonic waves act on the surface of thermoplastic plastics, it will produce tens of thousands of high-frequency vibrations per second. This kind of high-frequency vibration with a certain amplitude will transfer ultrasonic energy to the welding area through the upper weldment, and because the acoustic resistance at the interface between the two welds is relatively large, local high temperature will occur. Because of the poor thermal conductivity of plastic products, the accumulated energy can not be distributed in time, so the energy will be concentrated in the welding area, so that the contact surface of two pieces of plastic will melt rapidly, and after a certain pressure, it will be integrated. When the ultrasonic wave stops, let the pressure last for a few seconds to solidify and form a solid molecular chain, thus achieving the purpose of welding. In ultrasonic welding of metal, neither current nor high-temperature heat source is applied to the workpiece, but under the action of static pressure, the elastic vibration energy is converted into friction work, deformation energy and finite temperature rise at the interface of the workpiece, so that the metal atoms in the welding area are instantly activated and the molecules at the two-phase interface penetrate each other, and finally the solid connection of the metal weldment is realized. Schematic diagram of welding principle is shown in figure 1 [2].
2. 1 Advantages of ultrasonic welding technology
Compared with traditional welding technology, ultrasonic welding technology has the following advantages: (1) fast welding speed, high welding accuracy and high solder joint strength; (2) wide welding range, good stability and small deformation of the welded workpiece; (3) The surface of the weldment is clean, beautiful, flat and smooth; (4) no welding agent is needed during welding, the processed object is not polluted, and harmful gas is not generated, so it is an environment-friendly welding method; (5) When welding, welding can be carried out only by providing less power, and the energy consumption is low; (6) simple operation, low cost, high efficiency and good sealing performance.
Figure 1 Schematic diagram of ultrasonic metal welding principle
2.2 shortcomings of ultrasonic welding technology
Although ultrasonic welding technology has many advantages, it also has shortcomings, so we have to pay attention to it. Ultrasonic welding technology has the following shortcomings: (1) The understanding of ultrasonic welding mechanism is not comprehensive enough; (2) When welding metal, the weldment should not be too thick; (3) There are many factors affecting the ultrasonic welding process, which are difficult to analyze and summarize; (4) Some high-power ultrasonic welding machines have high manufacturing cost and great difficulty; (5) The quality of weldments is difficult to detect, which hinders mass production. 3 factors affecting the quality of ultrasonic welding
Although ultrasonic welding technology has many advantages, its welding quality is related to melting amount, material and other factors, including the following factors, as shown in Figure 2.
Fig. 2 Factors affecting the quality of ultrasonic welding
(1) Material of welding material: Generally speaking, the welding quality is related to the physical properties and modification of the material. Physical properties of materials include elastic modulus, friction coefficient, thermal conductivity, melting point and so on. The welding quality of an object is directly proportional to the elastic modulus, friction coefficient and thermal conductivity of the material, and inversely proportional to its density and melting point. Modification of materials refers to adding some fillers under suitable technological conditions to improve the original properties of materials and make them meet the requirements of customers. Under suitable technological conditions, adding some materials with similar properties can improve the strength of welded joints.
(2) Contact surface between welding head and weldment: The cleanliness of welding surface and the roughness of material surface will affect the welding quality of weldment. Increasing the surface roughness of the material can improve the welding quality; The higher the cleanliness of the welding surface, the higher the welding quality.
(3) Other factors: welding process parameters, the structure of the workpiece to be welded, the connection form, the melting amount during welding, the power of ultrasonic wave, etc. In order to achieve the best welding effect, these factors should be considered comprehensively in the product development stage.
4 Application cases of ultrasonic welding technology in industrial product design
As mentioned above, the research and development of products based on ultrasonic welding technology should first comprehensively consider the factors affecting welding quality, and then reasonably produce design elements in combination with market prospects, product costs, production technical requirements and other conditions.
The following is just a design case-patented ultrasonic plastic and metal welding technology invented by American Apple Company, to understand the application of ultrasonic welding technology in practice from a practical point of view. Disadvantages of the original technology: Before the invention of this patented technology, all portable devices (such as mobile phones) could not integrate metal and plastic, so some parts could not be replaced by plastic parts. The mobile phone produced in this way is not only heavy and dull in appearance, but also lacks individuality, freedom and flexibility in design. And the production cost is high, the operation is complicated, the use is inconvenient, and the contact will be invalid if the key operation is too much. Solution: The new ultrasonic plastic and metal welding technology is adopted, and some parts inside the mobile phone are made of plastic, which reduces the weight of the mobile phone and the amount of metal. The shell adopts one-step molding process, which makes the shell more concise and smooth, simple to operate and flexible in design, giving people the feeling of high-end atmosphere. Advanced ultrasonic welding technology generally adopts multi-material fusion technology, which makes the design more free and flexible. The design lines are minimalist and the colors are light, giving people a relaxed and pleasant feeling. The structure is more in line with the working principle of ultrasonic welding and the welding quality is better.
Summary and prospect of application of ultrasonic welding technology.
Through this investigation, the author studied the application of ultrasonic welding technology through his own understanding of ultrasonic welding technology. Due to the limited conditions, there are still some shortcomings in the investigation and research process. Here, the problems involved in the investigation and their solutions are summarized to pave the way for further research. In view of the welding quality problem, we come to the conclusion that during the welding process, the contact surface should be kept clean and the material surface should be kept rough. Understand the needs of users, design for specific users, design a variety of different appearance forms, tailor-made for different customers; In the design, we should also consider the issue of interest, design more interesting products and create a relaxed and pleasant environment. In view of the prospect of ultrasonic welding technology in product design, the author found that music playing function can be added to the work to make the welding process relaxed and happy. The future ultrasonic welding technology will also be more humanized.
refer to
Guan feldspar, fee. Principle and Practice of Ultrasonic Welding [J]. Mechanical Design and Manufacture, 2004(6).
Zhu, Wu, Fan Jinghui. Research Status and Prospect of Ultrasonic Metal Welding [J]. Welding Technology, 20 10/0,39 (12).