A method of connecting together two unit elements (4, 4′) of a fluid transport pipe, each unit pipe element being covered in an outer insulating coating (6, 6′) made of a thermoplastic material, with the exception of an end portion that does not have an outer insulating coating. The method includes: a step of welding together two abutting unit pipe elements; a step of positioning an annular sleeve (14) around a cut-back and in part around the outer insulating coatings of the two unit pipe elements, the sleeve being made of a thermoplastic material; a step of fastening the sleeve in sealed manner by weld bonding on the outer insulating coatings; and a step of applying an external pressure on the sleeve to enable it to be deformed elastically and match the shape of the respective end portions of the two unit pipe elements.

A connection, and methods of making an using such a connection, the connection comprising a first layer; a second layer concentrically disposed about the first layer; and a laser-induced seal between portions of the first and second layers; wherein the laser-induced seal provides a fluid-tight engagement between the first and second layers. As to particular embodiments of the connection, the first layer can be incorporated into a first conduit and the second layer can be incorporated into a second conduit.

A laser welding system for joining first and second thermoplastic workpieces, and including a clamp, an actuator, and a laser source. The clamp includes first and second clamping structures positioned together to engage opposite sides of the workpieces when they adjoin each other. The first clamping structure has a non-flat or irregular surface, facing the first workpiece. The actuator causes the clamping structures to press the first and second workpieces together. The laser source applies laser radiation having a wavelength of 2 microns toward the workpieces to be joined, while they are pressed together by the clamp, to melt irradiated portions of the workpieces to one another. The first clamping structure transmits substantially all of the energy of the laser radiation through the material. The first workpiece has a non-flat or irregular surface facing the first clamping structure, which substantially conforms with the surface of the first clamping structure.

A laser welding system is directed to simultaneously joining respective layers of a first bag and a second bag. The system includes a first film layer adjacent to a second film layer for forming the first bag, and a third film layer adjacent to a fourth film layer for forming the second bag, each layer of the plurality of film layers being made of a thermoplastic material that absorbs laser radiation having a wavelength of about 2 microns. A non-absorbing carrier film layer is positioned between the second film layer and the third film layer, the non-absorbing carrier film layer being made of a material that transmits substantially all energy of the laser radiation. A laser source applies the laser radiation toward portions of the plurality of film layers to be joined, forming the first bag generally simultaneously with the second bag.

A laser-welded body includes at least three of resin members, which contain a thermoplastic resin including: a first resin member which is a laser-irradiated subject, has an absorbance a.sub.1 of 0.01 to 0.12; a second resin member which has an absorbance a.sub.2 of 0.1 to 0.9 and includes a butted part where ends of one or more resin members are brought into contact with each other; and a third resin member which has an absorbance a.sub.3 of 0.2 to 3.8, and the absorbances a.sub.2, a.sub.3 exhibited by the second resin member and the third resin member are attributed to the inclusion of nigrosine as a laser beam absorbent therein, and the resin members are overlapped in the above mentioned to form contacted parts at these interfaces, at least a part of the butted part and/or the contacted parts are laser-welded.

A joining method for connecting at least two thermoplastic workpieces is provided to permit the joining even of non-transparent carbon fiber reinforced plastics parts by means of laser welding, in which a splice is produced at the edge regions of the workpieces and the workpieces are subsequently positioned relative to one another in such a manner that the opposite splice regions bound a seam region. Connecting bodies are then inserted into the seam region and heated by means of local heat input by laser beam such that a fixed integrally bonded connection forms between the workpieces and the connecting bodies.

A process for room temperature substrate bonding employs a first substrate substantially transparent to a laser wavelength is selected. A second substrate for mating at an interface with the first substrate is then selected. A transmissivity change at the interface is created and the first and second substrates are mated at the interface. The first substrate is then irradiated with a laser of the transparency wavelength substantially focused at the interface and a localized high temperature at the interface from energy supplied by the laser is created. The first and second substrates immediately adjacent the interface are softened with diffusion across the interface to fuse the substrates.

A connection, and methods of making an using such a connection, the connection comprising a first layer; a second layer concentrically disposed about the first layer; and a laser-induced seal between portions of the first and second layers; wherein the laser-induced seal provides a fluid-tight engagement between the first and second layers. As to particular embodiments of the connection, the first layer can be incorporated into a first conduit and the second layer can be incorporated into a second conduit.

Provided is a thermoplastic resin composition suitable for laser welding which has a laser transparency, a good laser weldability, mechanical properties, a high hydrolysis resistance, a laser-welded composite molded article such as a composite article obtained by laser-welding molded resin parts, and a method of laser welding such molded resin articles. The thermoplastic resin composition contains (A) polybutylene terephthalate, (B) polycarbonate, (C) reinforcing fiber, (D) epoxy compound, (E) carbodiimide compound, and (F) phosphorus-based stabilizer.

A process for room temperature substrate bonding employs a first substrate substantially transparent to a laser wavelength is selected. A second substrate for mating at an interface with the first substrate is then selected. A transmissivity change at the interface is created and the first and second substrates are mated at the interface. The first substrate is then irradiated with a laser of the transparency wavelength substantially focused at the interface and a localized high temperature at the interface from energy supplied by the laser is created. The first and second substrates immediately adjacent the interface are softened with diffusion across the interface to fuse the substrates.