Ultrasonic welding structure
The basic type of ultrasonic welding structure is to design a fuse line that runs through the entire welding plane on the welding plane, as shown in Figure 3-117. The basic ultrasonic welding structure is suitable for most occasions. Its disadvantage is that it may cause glue overflow on the fusion surface of the plastic parts, which affects the appearance quality of the product. //The basic type has many shortcomings.
Stepped welding is shown in Figure 3-118. The advantage is that by appropriately increasing the gap (0.13~0.51mrn) between the non-welding interface of the two plastic parts, the welding melt can be hidden in the gap 1, avoiding the occurrence of glue overflow, and having a higher appearance and surface quality.
//It's actually an art slot.
Step welding generally requires that the basic wall thickness of the part is not less than 2mm.
Groove type welding adopts pitch shift welding, and the concave-convex surface is designed to maintain a certain gap and slope, which is suitable for weldments that require complete sealing. At the same time, the grooved welding interface provides a self-positioning function. Properly increasing the gap (0.13~0.51mm) between the non-welded interface of the two plastic parts can prevent the occurrence of glue overflow, as shown in Figure 3-119.
Groove welding generally requires that the basic wall thickness of the part is not less than 3mm.
For semi-crystalline plastics, ultrasonic welding of ordinary structures, such as basic and stepped types, is difficult to ensure sufficient welding strength. This is because the conversion of semi-crystalline plastics from solid to molten state is completed in a short temperature range, and the conversion time is extremely fast, and vice versa. Therefore, before the molten plastic is fused with the plastic of the corresponding part, some of the plastic may have solidified, resulting in low welding strength.
For semi-crystalline plastics, it is recommended to use a shear welding structure design, as shown in Figure 3-120.