Basic knowledge of ultrasonic metal welding machine

1. Ultrasonic metal welding machine transmits high-frequency vibration waves to two metal surfaces to be welded. Under pressure, the two metal surfaces rub against each other, forming a fusion between molecular layers. Its advantages are high speed, energy saving, high fusion strength, good conductivity, no spark and close to cold working. The disadvantage is that the welded metal parts should not be too thick (generally less than or equal to 5 mm), and the solder joints should not be too large, which requires pressure.

2, welding advantages:

1), the welding material does not melt and is not fragile.

2) After welding, the electrical conductivity is good, and the resistance coefficient is extremely low or close to zero.

3) The requirement for welding metal surface is low, and it can be welded by oxidation or electroplating.

4) The welding time is short, and no flux, gas or solder is needed.

5), welding without sparks, environmental protection and safety.

3. Products suitable for ultrasonic metal welding:

1), Ni-MH battery Ni-MH battery Ni mesh and Ni plate melt with each other, and Ni plate melts with each other. .

2) Copper foil and nickel sheet of lithium battery and polymer battery are fused with each other, and aluminum foil and aluminum sheet are fused with each other. .

3) The wires are fused with each other, and one wire is partially fused with multiple wires.

4) Wires are fused with famous electronic components, contacts and connectors.

5) The integration of large heat sinks, heat exchange fins and honeycomb cores of famous household appliances and automobile supplies.

6), electromagnetic switch, fuse-free switch and other high-current contacts, dissimilar metal sheets melt each other.

7) The sealing and cutting of metal pipes can be waterproof and airtight.

4. Amplitude parameters

The amplitude is the key parameter of the material to be welded, which is equivalent to the temperature of ferrochromium. If the temperature is not reached, the welding will not be completed. If the temperature is too high, the raw materials will be burnt or the structure will be destroyed, and the strength will become worse. Because each company chooses a different transducer, the output amplitude of the transducer is also different. By using horns with different proportions, the working amplitude of horns can be corrected to meet the requirements. Generally, the output amplitude of the transducer is 10-20μ m, while the working amplitude is about 30μ m. The ratio of horn to horn is related to the shape of horn, the ratio of front and rear areas and other factors, such as exponential amplitude and shape. The easiest way for your company to choose different brands of welding machines is to manufacture them according to the size of the welding head that has been worked, so as to ensure the stability of amplitude parameters.

5. Frequency parameters

The ultrasonic welding machine of any company has a central frequency, such as 20KHz, 40 KHz, etc. The working frequency of welding machine is mainly determined by the mechanical vibration frequency of transducer, booster and horn. The frequency of the generator is adjusted according to the mechanical vibration frequency, so as to achieve consistency and make the horn work in a resonant state. Each component is designed. The * * * vibration frequency of generator and machinery has a resonant working range, such as 0.5 KHz, within which the welder can basically work normally. When we make each welding head, we will adjust the resonant frequency to ensure that the error between the resonant frequency and the design frequency is less than 0. 1 KHZ. For example, for 20KHz welding head, our welding head frequency will be controlled at 19.90-20 kHz.

6. Node

Both the horn and the horn are designed as half-wavelength resonators with operating frequency. In the working state, the amplitude of the two end faces is the largest and the stress is the smallest, while the amplitude of the node corresponding to the middle position is zero and the stress is the largest. The node position is generally designed as a fixed position, but the thickness of the fixed position is usually more than 3 mm, or the groove is fixed, so the fixed position is not necessarily zero amplitude, which will lead to some noise and some energy loss. For noise, rubber rings are usually used to isolate it from other components, or sound insulation materials are used to shield it, and energy loss is considered when designing amplitude parameters.

7. reticulation

Ultrasonic metal welding usually designs a grid on the surface of the welding position and the surface of the substrate. The purpose of grid design is to prevent metal parts from sliding and transfer energy to the welding position as much as possible. Mesh design generally includes square, diamond and strip mesh. The requirements of metal-coated welding head and base such as gold jewelry cannot be designed, and the size and depth of the mesh depend on the specific welding material requirements.

8, machining accuracy

Because the ultrasonic horn works under the condition of high-frequency vibration, it should be designed symmetrically as far as possible to avoid unbalanced stress and lateral vibration caused by asymmetry of sound wave transmission (the horn we use for welding adopts longitudinal transmission of ultrasonic vibration, which will lead to heat and fracture of the horn). The application of ultrasonic welding in different industries has different requirements for machining accuracy. For extremely thin workpieces, such as the welding of pole pieces and lugs of lithium ion batteries and the coating of gold foil, the requirements for machining accuracy are very high. All our machining equipment adopts numerical control equipment (such as machining center) to ensure the machining accuracy meets the requirements.

9. Service life

The service life of welding head depends on two aspects: one is material, and the other is technology.

Materials: Ultrasonic welding requires metal materials to have good flexibility (low mechanical loss during sound wave transmission), so the most commonly used materials are aluminum alloy and titanium alloy. However, ultrasonic metal welding requires the welding head to be wear-resistant (requiring high hardness), which makes the selection of materials very difficult, because hardness and toughness seem to be inherently opposite, which requires us to choose very harsh materials. The high-quality steel we choose can better solve this contradiction and make the effective life of the welding head as long as possible.

Technology: including processing technology and post-processing technology. The processing technology is introduced in detail, and the post-treatment includes heat treatment and parameter modification. Based on the materials selected by our company, we have the original heat treatment technology to ensure it. After each welding head is made, the parameters should be measured and adjusted separately to ensure the product.

10 metal compatibility

The compatibility of the above figure is for reference only, which is subject to the experiment.