Abstract: Systems, methods, and apparatus to weld by preheating welding wire and inductively heating a workpiece are disclosed. An example welding system includes: a welding current source configured to provide welding current to a welding circuit, the welding circuit comprising an electrode wire and a first contact tip of a welding torch; an electrode preheating circuit configured to provide preheating current through a first portion of the electrode wire via a second contact tip of the welding torch; and at least one induction heating coil configured to apply induction heat to a workpiece, the welding current source, the electrode preheating circuit, and the induction heating coil configured to perform a preheating operation and a welding operation on the workpiece.

Abstract: A workpiece stack-up that includes at least a steel workpiece and an aluminum-based workpiece can be resistance spot welded by employing a multi-stage spot welding method in which the passage of electrical current is controlled to perform multiple stages of weld joint development.

Abstract: A workpiece stack-up that includes at least a steel workpiece and an aluminum-based workpiece can be resistance spot welded by employing a multi-stage spot welding method in which the passage of electrical current is controlled to perform multiple stages of weld joint development. The multiple stages include: (1) a molten weld pool growth stage in which a molten weld pool is initiated and grown within the aluminum-based workpiece; (2) a molten weld pool solidification stage in which the molten weld pool is allowed to cool and solidify into a weld nugget that forms all or part of a weld joint; (3) a weld nugget re-melting stage in which at least a portion of the weld nugget is re-melted; and (4) a re-melted weld nugget solidification stage in which the re-melted portion of the weld nugget is allowed to cool and solidify.

Abstract: Provided is a spot welded joint (10) which includes at least one thin steel plate with a tensile strength of 750 MPa to 1850 MPa and a carbon equivalent Ceq of equal to or more than 0.22 mass % to 0.55 mass % and in which a nugget (3) is formed in an interface of the thin steel plates (1A, 1B). In a nugget outer layer zone, a microstructure consists of a dendrite structure in which an average value of arm intervals is equal to or less than 12 ?m, an average grain diameter of carbides contained in the microstructure is 5 nm to 100 nm, and a number density of carbides is equal to or more than 2×106/mm2.

Abstract: Resistance spot welding of a thin-gauge steel workpiece to another steel workpiece is achieved by through the combined use of specific spot welding electrodes and a pulsating welding current. Each of the spot welding electrodes has a weld face that is smaller in diameter than a typical steel spot welding electrode. And the pulsating welding current that is used in conjunction with the smaller-sized spot welding electrodes includes at least two stages of electrical current pulses.

Abstract: Provided is a method of resistance spot welding of welding a sheet set including a high strength steel sheet with which a high joint strength can be achieved even for a high Ceq material. A method of resistance spot welding a sheet set of two or more lapped steel sheets by weld the sheet set while clamping and pressing the sheet set between a pair of welding electrodes includes a first welding step of applying an weld current Im (kA) and forming a nugget having a nugget diameter d (mm) that satisfies the following inequality (1); a cooling step, subsequent to the foregoing first welding, of cooling the sheet set while continuing to press the sheet set; and a second welding step of performing two-step welding, 3×?tm?d?6×?tm??(1), where tm is the thickness (mm) of the thinnest one of the foregoing two or more steel sheets.

Abstract: A one-side resistance spot welding method includes a preheating step followed by a welding step. In the preheating step, an electric current having a smaller current value than a welding current is fed from a first electrode to second electrodes such that a substantially annular high-temperature region coaxial with the first electrode and having a higher temperature than neighboring parts is created in a workpiece due to resistance heat generation at a position located near a tip end of the first electrode. In the welding step, the annular high-temperature region forms a shielded current path due to its high electric resistance and serves to guide a welding current from the first electrode to flow into a bottom steel sheet of the workpiece via the shielded current path, thereby allowing the welding current to subsequently advance along the bottom steel sheet and reach the second electrodes via a top steel sheet.

Abstract: A method for monitoring the presence of an adhesive between two metal workpieces includes measuring the depth of indentation made by electric resistance weld electrodes by measuring the advance of the weld electrodes, and comparing the measured depth of indentation with the depth of indentation that is known to occur when the presence of the adhesive between the metal workpieces minimizes the shunting of weld current and thereby affects the depth of indentation. If the adhesive is absent, a supplemental electric resistance weld is made to compensate for the absent adhesive. The invention is applicable to both adhesive bonding, where only adhesive is used to attach the workpieces, and weldbonding, where an electric resistance weld is made atop a layer of adhesive.

Abstract: A flexible tube is placed in large and small furnaces separated by a heat-shield panel, and two kinds of jacket resin of the flexible tube are heated separately at different temperatures for their own softening points. A connecting area of the jacket resin enters the small furnace to a predetermined distance. In this connecting area, the jacket resin fails to reach the softening point temperature, and is not firmly welded to a blade. A cylindrical attachment is used to surround the spot that has lower temperature than the softening point, and hot air of approximately 250° C. is supplied from a spot heater into the cylindrical attachment. The spot in the cylindrical attachment reaches the softening point in a short time, and the jacket resin is welded to the blade.

Abstract: A spot welding apparatus for spot welding superposed workpieces by putting the superposed workpieces 3, 4 between a pair of electrodes 1, 2 and applying a welding current between the electrodes under application of pressure, the apparatus having heating coils 15 wound on each of the electrodes 1, 2, and being provided with high frequency heating means 17 for induction-heating welding portions of the workpieces contacted by the electrodes. The spot welding apparatus is capable of firmly spot welding workpieces made of high tension steel even if there is opening between the workpieces.

Abstract: A method of electrically welding a part such as a bolt around a bore of a composite sheet comprising an intermediate layer of a substantially insulating material disposed between two metal layers. Said sheet is pre-heated in the vicinity of said bore in order to remove said substantially insulating material therefrom, after which said part is welded onto said sheet by a conventional resistance spot welding method. Preferably, said pre-heating operation is conducted by passing an electric current between a counter-electrode applied to the sheet from the same side as said part to be welded, in the vicinity of said bore, and an electrode applied on said part to be welded.