ION MITELEA, ILARE BORDEASU, NICOLAIE VARZARU, ION DRAGOS UTU RESEARCH OF THE THERMAL GRADIENT AND QUALITY OF WELDED JOINTS FROM PVC THERMOPLASTICS FOILS AT HIGH FREQUENCY SYMMETRIC WELDING
Extending of the welding application field by high frequency currents of the thermoplastic polymers requires the full knowledge of the physical parameters which characterize the joining process of the welded joint. Since these engineering materials are extremely sensitive to temperature variations, the present paper highlights the role of the thermal gradient in obtaining of some welded joints with high mechanical strength and free from continuity defects. Regarding this, it is demonstrated that increasing the thickness of the polyvinyl chloride films, from 0.4 to 1 mm, the heat effect in the contact area of the electrodes is kept and the welding process has a high stability. For a well-run welding process is obtained a uniform distribution of the molten material in the joint area with positive impact on the breaking force values.
Keywords: high frequency welding, PVC foils, thermal gradient, quality