Today, the editor will analyze how to design the solder joints and welding surfaces when the ultrasonic plastic welding machine is working. Only by mastering this skill can you better use the ultrasonic plastic welding machine for production work.
1. Solder joint design
The design of welded joints refers to the design of a reasonable joint joint for ultrasonic spot welding of plastic materials. The solder joint structure is required to meet certain requirements in terms of continuous strength. At the same time, the appearance should be as beautiful as possible. The structure of the welding head is related to the thickness of the welding head. Let the thickness of the weldment be T, the shape of the welding spot is a convex ring, the inner diameter of the ring is 1.5T, the depth of the blind hole is 1.5T, around the blind hole A ring-shaped melted connection zone is formed in the range of 3T in diameter.
2. Design of welding surface
In order to concentrate energy in the plastic welding process, shorten the welding time, and improve the quality of jointing, the design of the welding surface is very important. The following editor introduces the centralized design method for everyone.
(1) Energy conducting triangle welding surface
On one side of the two plastic joints, add a small triangular flange along the welding surface. This flange concentrates the ultrasonic vibration on the sharp corners of the triangle, thereby reducing the welding contact area and forming concentrated ultrasonic energy. The dissolved plastic flows evenly over the welding surface, producing strong adhesive force, and greatly reducing the welding time. The wall thickness of the welding surface should be less than 2.5mm to get better results.
(2) Stepped welding surface
The step and the triangular flange make the welding force stronger. After the flange material is melted, it flows into the reserved gap, which can produce greater shear and tensile strength. This design can also avoid visible welding on the outside.
(3) Peak and valley type welding surface
A reinforced triangular flange welding surface. There should be gaps on both sides of the peaks and valleys to allow the plastic parts to be assembled easily and at the same time to allow the molten material to flow.
(4) Shear welding surface
Regardless of rectangular or circular parts, this welding surface has a high degree of sealing effect. Since a large amount of materials need to flow, high-amplitude and high-energy ultrasonic waves should be reserved between the welding surfaces to accommodate an appropriate amount of molten plastic, so as not to overflow outside and produce hairs. As a result of two plastic parts being squeezed vertically along the wall, the gap or gap is completely eliminated. This kind of welding surface is especially suitable for materials with crystalline structure and instant melting characteristics. When the welding depth is equal to 1.25 times the wall thickness, the strength is higher.
In short, the design of solder joints or welding surfaces is an important part of ultrasonic plastic welding, which should be designed according to specific weldments and requirements. Unreasonable design will cause problems such as overflow of molten material in the weld, and at the same time the welding strength will also be affected.
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