In a fastening method and fastening apparatus, workpieces are fastened using a fastener made of a thermoplastic polymer comprising carbon fibers. The method and apparatus involve induction heating of the carbon fibers to soften the thermoplastic polymer and then plastically deforming axial ends of the fastener using a die or dies to form first and second heads while a shaft body or a shaft part of the thermoplastic polymer comprising the carbon fibers is inserted through respective through holes formed in the workpieces.

A fastening apparatus includes a fastening device (1, 3) that heats in a non-contacting state, and then applies pressure to, a shaft part (11b) or shaft body (111) while it is inserted through the through holes (W10, W20) of workpieces (W1, W2), thereby forming at least a second head part (11c) of a fastener (11). The fastening device (1, 3) includes: a fastening die (15) that forms the second head part (11c); and a shaft-part pressure-applying device (9) that applies the pressure to the fastening die (15). A determining device (5) determines whether the fastener (11) is defective or not by calculating a load curve defined by the time and the load during which the pressure was applied and then determining whether an amount of change per unit of time in the load curve after a reference load has been exceeded is within a range of a predetermined reference value.

A method of controlling an inductive heating circuit, having a varying load, to seal a packaging material is provided. The method comprises generating AC power of at least two frequencies on at least one inductor in the inductive heating circuit; determining of the resulting phase shift in the inductive heating circuit from the current generated at the at least two frequencies; determining the impedance of the inductive heating circuit for each of the at least two frequencies; determining a load characteristics of the inductive heating circuit based on the relationship between the determined impedance and the determined phase shift; determining an impedance operating range; and selecting an AC output frequency for an induction power generator based on the load characteristics which results in the least amount of phase shift from a set ideal value and which is associated with an impedance that is within the impedance operating range.

Systems and methods are provided for controlling welding. One embodiment is a method for controlling welding. The method includes initiating induction welding by operating an induction coil along a weld interface of a first composite part comprising a matrix of thermoplastic reinforced by fibers, in order to join the first composite part to a second composite part, determining a measured magnetic field strength at a location distinct from the induction coil, and determining a welding temperature at the weld interface of the first composite part based on the measured magnetic field strength.

Systems and methods are provided for controlling welding. One embodiment is a method for controlling welding of a composite part. The method includes locating a linear fiber optic sensor along a composite part comprising a matrix of thermoplastic reinforced by fibers, measuring temperatures along the weld line via the linear fiber optic sensor, performing induction welding at the composite part along the weld line, determining a continuum of weld temperatures along the weld line, and controlling the induction welding based on the continuum of weld temperatures.

A heat sink for use in induction welding includes a number of tiles, wherein the tiles are electrically non-conductive and have a thermal diffusivity of greater than about 25 mm2/sec. A joint flexibly joins the tiles together.

A method for producing a metal-plastic-hybrid component comprises: providing a metal shaped piece, and providing a stiff plastics shaped piece made of a rigid thermoplastic. The geometry of the shape of the plastics shaped piece is at least partially adapted to that of the metal shaped piece. The method further comprises mechanically connecting the plastics shaped piece to the metal shaped piece in a manner such that the plastics shaped piece and the metal shaped piece are held against one another by intrinsic stress, and such that there is a substantial area of surface-contact between the plastics shaped piece and the metal shaped piece at at least one interface. The method further comprises inductively welding the plastics shaped piece to the metal shaped piece at the at least one interface.

A heat sink for use in induction welding includes a flexible backing and a number of tiles disposed on the flexible backing in a single layer, wherein the tiles are electrically non-conductive and thermally conductive.

A heat sink for use in induction welding includes a number of tiles, where the tiles are electrically non-conductive and thermally conductive, a joint flexibly joining the tiles together, and a fluid path formed through the heat sink for communicating a coolant therethrough.

A method of dissipating heat from a surface of a first thermoplastic composite (TPC) being inductively welded with a second thermoplastic composite (TPC) includes flexing a heat sink during placement to conform to the surface of the first TPC, cooling the heat sink, applying inductive heat to a weld interface area between the first TPC and the second TPC, and drawing off heat via the heat sink from the surface of the first TPC.