How to ensure the uniform heating of the material of the infusion bag pressure bag during the welding process

During the welding process of the infusion pressure bag storage air bag, ensuring uniform heating of the material is the key to guaranteeing the welding quality. The following elaborates in detail on how to achieve uniform heating of materials from aspects such as equipment selection, process parameter optimization, operation methods, and auxiliary measures:

1. Choose the right welding equipment
Heating method
High-frequency induction heating: High-frequency induction heating equipment uses the principle of electromagnetic induction to generate eddy currents inside the material and generate heat. This heating method can directly act on the inside of the material, with fast heating speed and good uniformity. For some infusion pressurized bag storage bag materials that require high heating uniformity, high-frequency induction heating is a good choice.
Equipment accuracy
Temperature control accuracy: Selecting welding equipment with a high-precision temperature control system can control the welding temperature within a very small fluctuation range. For example, the temperature control accuracy of some advanced welding equipment can reach ±1°C, which can ensure that the material is always at a suitable heating temperature during the welding process and avoid uneven heating due to temperature fluctuations.
Pressure control accuracy: Pressure will also affect the heating effect of the material, and uniform pressure distribution helps the material to be heated evenly. Therefore, equipment with high pressure control accuracy should be selected to ensure that the pressure is stable and evenly applied to the material during welding.
2. Optimize welding process parameters
Temperature setting
Material property matching: According to the melting point, thermal conductivity and other characteristics of the infusion pressurized bag storage bag material, the welding temperature should be reasonably set. For example, for materials with low thermal conductivity, the welding temperature needs to be appropriately increased, but it is necessary to avoid excessive temperature that causes the material to burn or deform.
Layered heating: For thicker materials, layered heating can be used. First, preheat the surface of the material at a lower temperature to gradually increase the temperature inside the material, and then adjust the temperature to the appropriate welding temperature for formal welding. This can reduce the temperature gradient inside the material and make the heating more uniform.
Heating time
Relationship between thickness and time: The heating time should be adjusted according to the thickness of the material. Thicker materials require longer heating time to ensure that heat can be fully transferred to the inside of the material. For example, for a material with a thickness of 1mm, the heating time may be 5-10 seconds; while for a material with a thickness of 2mm, the heating time may need to be extended to 10-15 seconds.
Real-time monitoring and adjustment: During the welding process, the temperature of the material can be monitored in real time by equipment such as infrared thermometers, and the heating time can be adjusted in time according to the temperature changes to ensure that the material is heated evenly.
Heating speed
Avoid too fast or too slow: Heating too fast will cause the surface temperature of the material to rise rapidly, while the internal temperature is low, resulting in a large temperature gradient, affecting the uniformity of heating; too slow heating will reduce production efficiency. Therefore, the appropriate heating speed should be selected according to the characteristics of the material and the capacity of the welding equipment. Generally speaking, the heating speed should be controlled so that the temperature difference between the surface and the inside of the material does not exceed a certain range (such as 10-20℃).
III. Improve the operation method
Welding path planning
Uniform coverage: During the welding process, the welding path should be reasonably planned to ensure that the welding heat source can evenly cover the entire welding part. For example, for the circular or elliptical airbag welding part, a spiral or circular welding path can be used to heat all parts of the material evenly.
Avoid repeated heating: Try to avoid repeated heating in the same part to avoid local overheating of the material. If multiple welding is required, the welding sequence and interval time should be reasonably arranged so that the material has enough time to dissipate heat and the temperature is uniform.
Stable operation method
Maintain a constant distance and speed: The operator should keep the distance between the welding heat source and the surface of the material constant and operate at a stable welding speed. Changes in distance and speed will affect the transfer and distribution of heat, resulting in uneven heating. For example, when using hot air welding, the distance between the hot air gun and the surface of the material should be kept at about 3-5mm, and the welding speed should be uniform and consistent.
4. Use auxiliary measures
Preheating treatment
Overall preheating: Before welding, the entire infusion pressurized bag storage bag can be preheated to increase the internal temperature of the material and reduce the temperature gradient during welding. Preheating can be carried out using equipment such as ovens and infrared heaters. The preheating temperature and time should be determined according to the characteristics of the material and welding requirements.
Local preheating: For some locally thicker parts or areas with lower temperatures, local preheating can be performed to improve the heating uniformity of these parts.
Use thermal conductive materials
Thermal conductive pads: Placing thermal conductive pads at the welding site can help heat transfer more evenly to the inside of the material. The thermal conductive pad should have good thermal conductivity and flexibility, and be able to closely contact the surface of the material.
Thermal conductive oil or thermal conductive paste: In some special welding processes, thermal conductive oil or thermal conductive paste can be used to improve the heat transfer efficiency. Applying thermal oil or thermal paste to the surface of the material can reduce thermal resistance and make heating more uniform.