Investigation On The Laser Welding Methods And The Properties Of Annular Weld Of Polymer Materials

With the popularization of polymer materials in the industry, the polymer material withlaser welding method is obtained more and more attention. Compared with the traditionalwelding process of high polymer material (ultrasonic welding and hot plate welding), the laserwelding of high polymer material have many advantages in technology and economy, such asfast speed, small thermal deformation, high welding quality, high degree of freedom, easy torealize automation, high stability and widely used in the high-end equipment manufacturingindustry. The laser welding system of polymer materials has a very large market and space dueto the science and technology become more and more mature. Besides, the research on laserwelding of polymer material in foreign has more advance than that in domestic. Therefore, it isextremely urgent to strengthen the study on laser welding of polymer material.The characteristics on optics and thermodynamics of polymer materials are investigatedin this work. The principles and characteristics of laser transmission welding of polymermaterials are analyzed. The annular laser beam welded joint is investigated, the optical systemand forming principle are analyzed. The results show that: under the circumstance of constantdistance between the two axicon lens, with the increasing focal length of the collimating lens,the outer diameter of the ring beam almost has no change, and the inner diameter is decreased.So the width of ring laser beam is increased. Under the circumstance of constant focal lengthof the collimating lens, with the increasing length of the axicon lens, the diameter of the innerand outer ring laser beam are both increased, and the width of the ring laser beam almost hasno change. The uneven distribution intensity of ring beam can be improved by adjusting thecoaxial between the collimating lens, first axicon and second axicon. The uneven width of thering beam can be improved by adding a homogeneous mirror between the collimating lens andthe first axicon.The optimum technology parameters between the TPV elastomer and PP in this work areas follows, the test pressure is200N, the beam width is3.5mm, the laser output power is800W and the laser irradiation time is0.6s. The tensile shear strength can be reached2.40MPaand the fracture position of stretch part is appeared in the base material under the optimumtechnology parameters. It can be concluded from the laser welding technology experiment of polymer materials that the joint which meets the technical requirement can be obtained in awide range between the TPV elastomer and PP. If the value of the heat input is low, it can beeasy to cause a bad joint surface. If the value of the heat input is too high, it can be easy tocause the polymer materials splitting decomposition, so the defects are appeared in the jointsurface, such as ablation or pores.