Ultrasonic professional production of ultrasonic plastic welding machine, ultrasonic plastic welding requires reasonable welding design.
The reasonable welding structure is one of the key conditions to ensure the best welding effect. The design of all kinds of welding joints depends on a variety of factors, such as material type, part shape and welding requirements (i. e. strength, seal, appearance, etc.).
A reasonable welding design is represented by ultrasonic welding, which represents the typical design of the guide wire. For some resins that require high energy (i.e. amorphous, low stiffness or high melting point), the size of the conductive wire should increase by 1.5~2 times compared to the same period. When the weldment is not sealed, the welding line can be interrupted to reduce energy consumption.
Fig. two shows the design of the outer shielded weld joint, which is also designed to be bidirectional shielding when necessary, so as to avoid overflowing to ensure the appearance quality. The design should ensure the a more than B.
Fig. three shows the shear welding method that needs to be tightly sealed. It is especially suitable for crystalline resin (PP, PE, Nilon, POM, etc.). For the connection requirements exceeding the strength of welded parts, it is recommended that the penetration depth is 1.25 times that of the wall thickness. The amount of shear is directly proportional to the size of the weldment, generally 0.2~0.5mm. The shear welding fixture must limit the flexure and deformation of the workpiece, and the ultrasonic head and the upper workpiece should be as close as possible to the weld (like a cover) to prevent the workpiece from flexing inward. For intermediate wall shear welding, the tenon groove structure shown in Fig. four can be used to avoid flexural deformation.
Due to high pressure and intense vibration in ultrasonic energy transfer, the following structural hazards should be avoided in welding design.
1. The contact surface of ultrasonic head and / or ultrasonic tooling and weldment is too small to produce indentation and blotch on the surface of the weldment. It is suggested that the contact area should be three times larger than the welding area and as far as possible against the welding area (Fig. two).
2, the workpiece on the cover is too thin, easy to crack under resonance, or "breakdown". It is recommended to reinforce the processing (Figure two).
3, small attachment and main connection strength is too weak, easy to break, it is recommended to add a circle R at the root (Fig. three).
4, the structural bearing capacity is not good, resulting in energy can not be effectively transmitted to the joint surface. If this design can not be avoided, the surface of the ultrasonic head and the ultrasonic tooling should be changed to a good load position (Fig. four).
In addition, the fixture also affects the welding effect to a great extent. The material, shape, wall thickness and asymmetry of the welded parts may affect the transfer of energy to the interface. All these require careful design of tooling and fixtures to ensure uniform load on the welding interface.
For some weldments, the bonding surface may be too strict to produce relative displacement, and the rigidity of the ultrasonic tooling can be reduced properly so as to ensure the different phase state in the joint.
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