Influencing factors of ultrasonic metal welding

Amplitude
Amplitude is a key parameter for the material to be welded and is equivalent to the temperature of ferrochrome.
If the temperature does not reach, it will not be fused, and if the temperature is too high, the raw material will be scorched or the structure will be damaged and the strength will deteriorate.
The choice of ultrasonic transducer is different, the output amplitude of the transducer are different, after adapting different ratios of ultrasonic amplitude rod and welding head, can correct the working amplitude of the welding head to meet the requirements. Usually the output amplitude of the transducer is 10-20μm, while the working amplitude is generally about 30μm, the variable ratio of the amplitude rod and welding head is related to the shape of the amplitude rod and welding head, the front and rear area ratio and other factors.
The shape, such as exponential amplitude, function amplitude, step amplitude, etc., has a great impact on the variation ratio, and the front-to-back area ratio is proportional to the total variation ratio. The selection is a different brand of welding machine, the easiest way is to make the proportional size of the welding head that has been working, can ensure the stability of the amplitude parameters.
Frequency
Any ultrasonic welding machine has a central frequency, such as 20 KHz, 40 KHz, etc. The working frequency of the welding machine is mainly determined by the mechanical resonance frequency of the ultrasonic transducer (Transducer), the ultrasonic amplitude rod (Booster), and the welding head (Horn).
The frequency of the ultrasonic generator is adjusted according to the mechanical resonance frequency to achieve consistency, so that the welding head works in a resonant state, and each part is designed as a half-wavelength resonant body. Both the ultrasonic generator and the mechanical resonant frequency have a resonant operating range.
Generally set to ± 0.5 KHz, within this range of welding machine can basically work properly, we make each welding head, will make adjustments to the resonant frequency, the requirement to achieve the resonant frequency and the design frequency error is less than 0.1 KHZ. 20KHz welding head, we will control the frequency of the welding head in 19.90-20.10 KHZ, the error is small 5 ‰.
Nodes
Nodes, welding head, ultrasonic variable amplitude rod are designed as a working frequency of half-wavelength resonant body, in the working state, the two end surfaces of the maximum amplitude, the minimum stress, while the node equivalent to the middle position of the amplitude of zero, the maximum stress.
The node position is generally designed as a fixed position, but usually the fixed position is designed with a thickness of more than 3mm, or a groove fixed, so the fixed position is not necessarily zero amplitude, which will lead to some shouting and part of the energy loss, for the shouting is usually isolated with rubber rings and other components, or the use of acoustic insulation materials for shielding, energy loss in the design of the amplitude parameters to be considered.
Mesh
Ultrasonic metal welding is usually designed with a mesh pattern on the surface of the weld position and the base surface. The purpose of the mesh pattern design is to prevent the metal parts from sliding and to transfer as much energy as possible to the fusion position. The mesh design generally has a square, diamond, bar mesh. Gold hand jewelry and other metal clad welding head and base as required can not be designed pattern, the size and depth of the pattern according to the specific requirements of the welding material to determine.
Transducer
[span] for metal welding devices used in the transducer and for plastic welding devices used in the transducer is not very different, the special feature is to weld metal with higher quality requirements, because in welding metal often requires a large instantaneous power, requiring the transducer to have a high power capacity and low impedance, without the use of plastic welding devices used in the transducer.
Power source
There is no major difference between the ultrasonic power source used for metal welding equipment and the ultrasonic power source used for plastic welding equipment. [span]The special feature is that welding metal has higher requirements, in order to meet the needs of metal welding, it is necessary to use an intelligent ultrasonic power source – ultrasonic generator.
[span]The ultrasonic generator has a frequency automatic tracking system, in the welding process of mechanical devices or electronic components of the work situation will cause changes in vibration frequency, [span]The ultrasonic generator will track the frequency of the vibration system, so that the generator and vibration system has been in a state of resonance between the generator, frequency automatic tracking system can compensate for changes in the working state during the welding process, so that The automatic frequency tracking system can compensate for changes in the working state during the welding process, so that the system is back in a resonant state and the stability of the welding parameters, with emphasis on the stability of the amplitude, which is of great importance for metal welding.

Translated with www.DeepL.com/Translator (free version)

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