The principle and application of high-frequency welding for multi-unit blood bags

I. Principle of High-Frequency Welding for Blood Bag Multi-Packs

High-frequency welding utilizes high-frequency electromagnetic energy to generate heat at the interface of plastic materials with high-loss dielectric properties, achieving fusion of the plastics. Specifically, the high-frequency welding machine uses a vacuum tube self-excited oscillator to generate a high-frequency electric field. Under the influence of this electric field, the molecules in the plastic material of the blood bag multi-pack align in the opposite direction to the electrodes; that is, positive charges move to the negative pole, and negative charges move to the positive pole. When the direction of the electric field changes, the position of the charges also changes; this displacement of charges is called polarization. During polarization, molecules overcome frictional resistance, consuming energy, which is released as heat, thus heating the plastic. Under the pressure of the mold, two or more layers of plastic film can be bonded together, achieving the welding purpose.

II. Applications of High-Frequency Welding for Blood Bag Multi-Packs

1. Welding of Medical Blood Bags: High-frequency welding is the preferred equipment for plastic heat sealing and is commonly used in the medical field for welding medical fluid bags, such as blood bags, infusion bags, and urine bags. 1. **High-frequency welding of PVC bag openings:** This ensures a sterile seal, meeting the high hygiene and safety requirements of the medical industry.

2. **Improved production efficiency:** Taking the automatic sliding table high-frequency welding machine for medical bags as an example, it can be applied to welding multi-unit blood bags. This equipment can complete the welding of bags containing PVC components in one go, addressing the issue of welding the bag first and then the tubing, thus improving product efficiency and quality. The forming time can be controlled by setting time relays, such as the die head descent delay time, welding time, cooling time, and ascent time, achieving precise control of the welding process.

3. **Adaptability to diverse product needs:** When using high-frequency welding machines for heat sealing multi-unit blood bags, different products only require mold changes, demonstrating strong versatility and flexibility, and meeting the diverse production needs of the medical industry.