APPARATUS AND PROCESS FOR JOINING AT LEAST TWO ITEMS COMPOSED OF THERMOPLASTIC MATERIAL BY MEANS OF LASER RADIATION

摘要

An apparatus and a process are described for joining at least two items each composed of thermoplastic material by means of laser radiation, using a laser emitting the laser radiation and using at least one element focusing the laser radiation onto a three-dimensional region, where at least sections of the two items have a shared joining plane and the two items enter into a mutual cohesive bond when the laser radiation melts the material, and where the wavelength of the laser radiation has been selected in such a way that the laser radiation can be absorbed to some extent on passage through the thermoplastic material of each of the two items. A feature of the invention is that at least one optical element influencing the laser beam has been provided and gives the laser beam a geometric beam shape and/or a beam intensity distribution along at least one beam-cross-section plane in which the laser beam has a central laser beam region and has at least one laser beam region at least to some extent peripherally surrounding the central laser beam region, and that a lower laser beam intensity prevails in the central laser beam region than in the at least to some extent peripherally surrounding laser beam region, and that the beam-cross-section plane is at least in the region of a surface of at least one item, by way of which surface the laser beam penetrates one of the items, and that in the joining plane the peripheral at least to some extent surrounding laser beam region and the central laser beam region can be focused onto the three-dimensional region and give a laser beam intensity which is sufficient to melt the two items in the three-dimensional region.