Ultrasonic matel welding
The ultrasonic welding machine seems to be a device with no difficulty except the ultrasonic system. In fact, this is a wrong view. Although the ultrasonic generator, transducer, and welding head are important parts of the ultrasonic welding machine, except for the generator part There is also the problem of the metal machine frame. If a set of frame design is not reasonable enough and the processing is not precise enough, it is likely to directly affect the welding pass rate of your product during use. If the machine design is unreasonable, it will cause the machine to recline. That will also affect the welding fastness of the product, and if the processing is not precise and rough, it is impossible to find a better balanced position of the mold when changing the mold, so it may also cause the welded product to fail to weld.
In the context of global advocacy of conservation and environmental protection, new energy vehicles have become an inevitable trend in the development of automobiles in the world. PricewaterhouseCoopers released the Blue Book of China's Auto Industry on December 8 that China's new energy vehicle sales are far ahead of other markets in the world. With the vigorous support of new energy vehicles, China's new energy vehicle era has arrived. In 2015, the global sales of new energy vehicles reached 500,000, of which 330,000 were sold in China, which was three times the previous year and far ahead of other markets in the world. At the same time, more disruptive intelligent connected vehicles were also With accelerated development, Internet giants and other emerging players are actively pouring into the market, putting pressure and impact on traditional automakers and dealers. There is no doubt that new energy and intelligent networked vehicles have become the mainstream of the automotive industry's renewal, and the demand for applicable wiring harnesses will also greatly increase.
Foreign countries have conducted more in-depth research on the technology of ultrasonic metal welding. The following is an introduction to the foreign research status of this technology from two aspects of experiment and simulation research. Through a large number of experiments, Kong et al. of Loughborough University in the United Kingdom have respectively obtained the relatively good range of seam welding welding process parameters for the two aluminum alloy sheets of 0.1mm thickness 3003 and 6061, and combined with the linear welding density (the real welding connection area accounts for the entire The ratio of the welding area) and the peel strength of the welding sample and the microstructure analysis to evaluate the welding quality of the sample. Experiments show that under the dual effects of ultrasonic vibration and static pressure, friction and plastic flow are generated at the welding interface, causing the oxide film on the surface of the aluminum alloy sheet at the welding interface to break and gradually form connection points; as the vibration continues, the oxide film will be It is blocked outside the welding interface and dissipated under a larger amplitude, resulting in higher linear welding density and weld strength. Because there is an oxide film on the surface of the 6061 aluminum alloy sheet, friction cannot be effectively generated during the welding process to break and disperse the oxide film, making it difficult to produce welding joints between the sheets; pre-treatment of the surface of the 6061 aluminum alloy sheet before welding can effectively improve its Welding linear density.
The connection of copper wire and aluminum Busbar requires consideration of the combination of two substances
a) The element potential difference between copper and aluminum will cause electrochemical corrosion
b) At high temperatures, the two elements may form intermediate compounds, the interface resistance increases and becomes brittle
c) When processing here, perform plating treatment on the aluminum Busbar, and use connection point sealant after welding (form airtight conditions to block electrochemical corrosion)
d) The expansion coefficient of aluminum is as high as 39% greater than that of copper. When two metal conductors are connected and current flows, the connection point heats up due to the contact resistance, and both conductors expand. If the temperature rise is not controlled properly, some potential problems may be caused.
If some problems are connected with the copper-aluminum Busbar, this problem is relatively small. If the switch is not used, how to ensure the long-term reliability of this contact without sealing compound poses a new challenge.
Both the welding head and the ultrasonic horn are designed as a half-wavelength resonator of the working frequency. In the working state, the amplitude of the two end faces is relatively large and the stress is relatively small, and the amplitude of the node at the middle position is zero, and the stress is relatively Big. The node position is generally designed as a fixed position, but the thickness of the usual fixed position is greater than 3mm, or the groove is fixed, so the fixed position is not necessarily zero amplitude, which will cause some calls and a part of energy loss. Calls are usually isolated from other parts by rubber rings, or shielded by a vibration reduction structure design. The energy loss should be fully considered when designing the amplitude parameters. The rubber ring is called soft fixation, and the vibration reduction structure design is generally called hard fixation. In ultrasonic metal welding, a hard fixed structure is usually used, and the hard fixed structure also has an end surface fixed mode.
Ultrasonic welding machines can be divided into automatic welding machines, semi-automatic ultrasonic welding machines, and manual welding machines according to the level of automation. For modern enterprises, the higher the level of automation, the more conducive to the production of enterprise assembly lines, so the use of automatic welding machines is a future for enterprises trend. When an object vibrates, it makes a sound. Scientists call the number of vibrations per second the frequency of sound, and its unit is hertz. The frequency of sound waves that our human ears can hear is 20HZ～20000Hz. Therefore, when the vibration of the object exceeds a certain frequency, that is, higher than the upper limit of human hearing threshold, people will not be able to hear it. Such sound waves are called "ultrasound." The ultrasonic frequency usually used for medical diagnosis is 1 to 5 MHz.
