How is the ultrasonic rotary sewing machine welding the filter?

How is the ultrasonic rotary sewing machine welding the filter?

Ultrasonic continuous welding of PP filter elements is a highly efficient filter element welding process. The following is a detailed introduction:
Working Principle: Similar to conventional ultrasonic welding, an ultrasonic generator generates a high-voltage, high-frequency electrical signal, which is converted by a transducer into mechanical oscillations of the same frequency. This signal acts on the PP filter element workpiece in the form of audio-frequency longitudinal waves. However, in continuous welding, the workpiece continuously passes through the welding area, and ultrasonic energy is continuously applied to the weld zone. This generates heat through friction between the PP material molecules, rapidly melting the interface. The weld then cools and solidifies under pressure, achieving a continuous welding process.

Equipment Features:
High Level of Automation: Automated conveying is typically used to enable continuous loading, welding, and unloading of PP filter elements, reducing manual intervention and improving production efficiency. For example, Telsonic's ultrasonic welding equipment uses a linear encoder to weld based on distance or absolute distance. A touchscreen interface allows users to adjust welding parameters such as time, energy, and maximum power, and also allows for input and saving welding plans.
High Welding Speed: Suitable for large-scale production, it can weld large quantities of PP filter elements in a short period of time. For example, single-point welding with acoustic peak ultrasonic welding technology takes only 0.5-2 seconds, significantly improving production efficiency.
Stable welding quality: By precisely controlling welding parameters such as amplitude, frequency, pressure, and welding time, consistent weld quality is ensured from one weld to the next, ensuring excellent sealing and airtightness.

Application scenarios:
Pleated filter element welding: Used for continuous welding and sealing of the longitudinal seams of pleated filter membrane material to form circular filter elements. Suitable for the production of pleated filter elements of various sizes, with pleat depths up to 50mm and lengths ranging from 250mm to 1500mm.
Multi-layer filter element calendering welding: Continuously operating at high speed, calendering welds multiple layers of PP material to create laminated multi-layer filter media, preparing for downstream filter element production.

Ultrasonic sewing machines can be used for welding pleated box filter elements.
Ultrasonic sewing machines generate heat through high-frequency vibration, causing friction between the molecules of the filter element material, thus achieving the welding effect. In the production of bellows filter elements, ultrasonic sewing machines weld and seal the longitudinal seams of the folded filter membrane material, creating a circular filter element. Ultrasonic welding offers advantages such as high welding speed, consistent quality, and the absence of glue, improving production efficiency and ensuring the seal and reliability of the filter element.

II. Core Welding Stage: Welding Key Components of the Filter Element in Steps
Ultrasonic welding of bellows filter elements primarily targets the longitudinal seams (the seams where the filter membrane is folded) and the seams connecting the end cap and the filter membrane. These operations must be performed sequentially to ensure a leak-proof seal. Step 1: Filter Membrane Positioning and Transport
Place the folded filter membrane neatly on the feed table of the ultrasonic sewing machine. Adjust the positioning baffles (one on each side) to align the longitudinal joint edge of the filter membrane (the edge to be welded) with the centerline of the welding head, with a deviation of no more than 0.5mm (to avoid weld seam deviation and seal failure).
Start the automatic transport device (if using a semi-automatic machine, manual assistance is required). Feed the filter membrane smoothly into the welding area at the preset speed, ensuring that the membrane folds do not shift or overlap during transport. Step 2: Continuous Welding of the Longitudinal Seam (Core Process)
When the spliced ​​edge of the filter membrane reaches the bottom of the welding head, the ultrasonic generator activates. The transducer converts the high-frequency electrical signal into mechanical vibrations, which are transmitted to the welding head via the horn.
The welding head applies a preset pressure and vibration energy to the spliced ​​edge of the filter membrane, causing molecular friction at the membrane interface to generate heat, rapidly reaching the melting point (PP melting point is approximately 160-170°C), and the molten material fills the gap at the interface.

The filter membrane is continuously conveyed, and the welding head moves synchronously with the conveyor (or the welding head is fixed while the membrane moves), forming a continuous strip weld (the weld width is typically 2-5mm, adjusted according to the membrane thickness to ensure that the spliced ​​gap is covered).

During the welding process, the weld status is monitored in real time. If a leak occurs (partial weld is missing), the machine is immediately paused to check whether the filter membrane positioning is offset or the parameters are correct. If a weld break occurs (membrane damage), the amplitude or pressure is reduced and the weld is retested. Step 3: Welding the End Caps/Frame to the Filter Membrane (Optional, Depending on the Filter Element Structure)

If the bellows filter element requires end caps (such as upper and lower end caps), after the longitudinal seam welding is complete, place the membrane cartridge (the cylindrical structure formed by the welded filter membrane) onto the support frame and install the end caps at each end.
Replace the welding head with a suitable end cap (usually a circular or square head to suit the end cap shape) and adjust the equipment parameters (the amplitude can be increased to 60-90μm and the pressure to 0.3-0.6MPa. Since the end cap is thicker than the filter membrane, higher energy is required).
Align the end cap and filter membrane joint with the welding head and initiate welding. Melt the end cap and filter membrane at the contact point, forming a circular weld (3-6mm wide). Ensure there is no gap between the end cap and the filter membrane to prevent fluid leakage through the gap in the end cap.