Ultrasonic Plastic Welding Machine Welding Head Mould
The welding head is a tool that effectively transmits vibration to the plastic welding part. It has the following functions:
1. Transmission of vibration energy
2. Transfer pressure
3. Transmission amplitude
4. Provide a shape consistent with the shape of the product, and because the plastic is malleable, it can fit the product to a certain extent.
The design and manufacture of the welding head must be very careful, because only a good welding head can guarantee a good welding result. If the welding head is poorly designed (amplitude design, unreasonable mode shape), poor manufacturing (material selection, improper frequency repair), it may cause the welding head to break and fail.
Welding head material selection and restrictions
Usually, three different materials are used to make welding heads, each of which has its own unique properties. The choice should be made according to the requirements and expectations of use.
· Aluminum alloy: used for soft mold verification process stage or small batch production stage, can not withstand mechanical stress. Or for large welding heads where weight and cost are important considerations. This is one of the most commonly used materials, with good mechanical properties (hardness and ultrasonic propagation speed) and economy.
· Titanium alloy: used in the small, medium and mass production stages of the product, has excellent acoustic properties, can withstand the maximum mechanical stress 3 times that of aluminum alloy, and has relatively excellent wear resistance. At the same time, the wear resistance of the welding head can be greatly increased by carrying out a specific surface treatment on the surface of the welding head. It is often used for welding plastics containing glass fiber.
· Alloy steel: Used for welding plastic parts that cannot be applied to aluminum alloy and titanium alloy. It has high hardness and highest wear resistance. Generally, it must be hardened before use. This material is often used in ultrasonic metal screw inlay applications.
Types and characteristics of ultrasonic welding heads
There are different types of welding heads to suit different application requirements. For example: a small, high gain (high amplitude output) circular welding head is used to weld small rectangular parts; a large rectangular welding head outputs small amplitude and is used to weld large parts. The most common types are as follows:
· Stepped Horn: The two ends of the weld head have different cross-sections, and the two cross-sections transition through the fillet at the weld head node position. The stepped welding head has a high gain and large amplitude output due to the sudden change in the plane section of the node, and the mechanical stress is also relatively large. This type of welding head is suitable for ultrasonic welding, riveting, falling off and other processes.
· Exponential Horn: The shape of the welding head changes according to the exponential formula. The cross section gradually transitions, and the internal stress is distributed in a longer area to reduce the peak stress. Therefore, this type of welding head has ideal stress distribution and excellent fatigue strength. It is suitable for applications with high welding pressure and small amplitude output, such as metal screw inlay.
· Catenoid welding head: Combines the advantages of stepped high gain and exponential low stress. Suitable for welding and riveting various small parts.
· Rectangular (Rectangular) or round (Bar) welding head: common design. Small-sized rectangular welding heads also usually adopt a stepped design. Generally, the width of the welding head is greater than 88mm. In order to avoid the transverse vibration and stress of the welding head, a groove must be added to its structure. The maximum size of the standard rectangular welding head can be 250mm.
· Circular Horn: Including hollow or solid welding heads. Usually used for plastic parts whose welding area is round. Circular welding heads with a diameter of more than 88mm usually add grooves to allow axial vibration.
Contact Person: Ms. Hogo Lv