1. Basic knowledge of ultrasonic metal welding
Ultrasonic metal welding uses high-frequency vibration waves to transmit to two metal surfaces to be welded. Under pressure, the two metal surfaces rub against each other to form a fusion between molecular layers. The advantages are fast, energy-saving, and fusion. High strength, good electrical conductivity, no spark, close to cold processing; the disadvantage is that the welded metal parts should not be too thick (generally less than or equal to 5mm), the solder joints should not be too large, and need to be pressurized.
2. Welding advantages:
1) non-melting and non-brittle metal properties of welding materials.
2) good electrical conductivity after welding, very low or almost zero resistance coefficient.
3) low requirements for welding metal surface, oxidation or electroplating can be welding.
4) short welding time, no need for any flux, gas or solder.
5) no spark in welding, environmental protection and safety.
3. Suitable products for ultrasonic metal welding:
1) Nickel-metal hydride battery Nickel-metal hydride battery nickel mesh and nickel sheet inter-melting and nickel sheet inter-melting. .
2) Lithium battery, polymer battery copper foil and nickel sheet are mutually melted, and aluminum foil and aluminum sheet are mutually melted. .
3), the wires are mutually melted, and the ones are entangled into one and a plurality of mutually melted.
4), the wire and the name of the electronic components, contacts, connectors and mutual fusion.
5), the mutual melting of large-scale heat sinks, heat exchange fins, and honeycomb hearts of famous household appliances and automotive products.
6), electromagnetic switch, no fuse switch and other large current contacts, mutual melting of dissimilar metal pieces.
7) The sealing and cutting of the metal pipe can be water and airtight.
4, amplitude parameters
The amplitude is a key parameter for the material to be welded, which is equivalent to the temperature of ferrochrome. If the temperature is too low, it will not be welded. If the temperature is too high, the raw material will burn or cause structural damage and strength. Because the transducers selected by each company are different, the amplitude of the transducer output is different. After adapting the different ratios of the horn and the horn, the working amplitude of the horn can be corrected to meet the requirements. The output amplitude of the energy device is 10-20μm, and the working amplitude is generally about 30μm. The transformation ratio of the horn and the welding head is related to the shape of the horn and the welding head, the front-to-back area ratio and other factors, and the shape is exponential. Variable amplitude, functional amplitude, stepped amplitude, etc. have a great influence on the ratio, and the area ratio before and after is proportional to the total ratio. The welding machine of different company brands is selected. The simple method is to make the proportion of the working welding head, which can ensure the stability of the amplitude parameters.
5, frequency parameters
Any company's ultrasonic welding machine has a center frequency, such as 20KHz, 40 KHz, etc. The working frequency of the welding machine is mainly the mechanical resonance frequency of the transducer, the horn, the horn and the horn. It is determined that the frequency of the generator is adjusted according to the mechanical resonance frequency to achieve uniformity, so that the horn operates in a resonant state, and each part is designed as a half-wavelength resonator. Both the generator and the mechanical resonant frequency have a resonant operating range. For example, the general setting is ±0.5 KHz. In this range, the welding machine can basically work normally. When we make each welding head, the resonant frequency is adjusted. The resonance frequency and design frequency error is less than 0.1 KHZ. For example, the 20KHz welding head, the frequency of our welding head will be controlled at 19.90-20.10 KHz with an error of 5 ‰.
6, the node
The welding head and the horn are designed as a half-wavelength resonator with an operating frequency. Under the working condition, the amplitude of the two end faces is the largest and the stress is the smallest, and the amplitude of the node corresponding to the intermediate position is zero and the stress is the largest. The position of the node is generally designed to be a fixed position, but the usual fixed position is designed to have a thickness greater than 3 mm, or the groove is fixed, so the fixed position does not necessarily have a zero amplitude, which causes some sound and part of the energy loss. The sound is usually isolated from the other components by a rubber ring or shielded with a sound insulating material. Energy loss is taken into account when designing the amplitude parameters.
Ultrasonic metal welding usually involves the surface of the welding surface, and the surface of the base is designed with a netting. The purpose of the mesh design is to prevent the sliding of the metal parts and transfer the energy to the welding position as much as possible. The mesh design generally has a square, diamond, and strip mesh. Gold-clad metal and other metal-clad welding heads and bases are required to be designed without texture. The size and depth of the mesh are determined according to the specific welding material requirements.
8, processing accuracy
Because the ultrasonic welding head works under high frequency vibration, it should maintain a symmetrical design to avoid the unbalanced stress and lateral vibration caused by the asymmetry of sound wave transmission. The welding head we use for welding uses the longitudinal direction of ultrasonic vibration. Transmission, for the entire resonant system), unbalanced vibration can cause heat and breakage of the weld hair. Ultrasonic welding is applied to different industries and has different processing precision requirements. For particularly thin workpieces such as lithium ion battery pole pieces and tab welding, gold foil coating, etc., the processing precision is very high, all our processing equipment All CNC equipment (such as machining centers, etc.) are used to ensure that the precision of the machining meets the requirements.
9, the service life
The service life of a welding head is determined by two aspects: first, material, second, process
Materials: Ultrasonic welding requires good metal properties (good mechanical loss during sonic transmission), so the commonly used materials are aluminum alloy and titanium alloy, but ultrasonic metal welding requires welding head wear resistance (higher requirements) Hardness) makes the choice of materials more difficult, because hardness and toughness seem to be inherently opposite, which requires us to choose very high-demand materials. The high-quality steel materials we choose can solve this contradiction better. The effective life of the weld head is maximized.
Process: including processing technology and subsequent processing technology, the processing technology has been described in detail before, the subsequent processing includes heat treatment and parameter modification, based on the materials selected by our company, we have original heat treatment process to ensure; in each welding After the head is completed, the parameters are measured and adjusted separately to ensure the product is produced.
Contact Person: Ms. Hogo Lv