198results about "Welding electric supplies" patented technology

When two high-strength steel sheets (1A, 1B) having a sheet thickness ratio of 2 to 5, inclusive, and both having a tension strength of 780 MPa to 1850 MPa, inclusive, are overlapped with each other and resistance spot welding is performed, a first energizing process that is a preliminary energization with an applied pressure of P1 kN and a welding current of I1 kA and a second energizing process that is a main energization with an applied pressure of P2 kN and a welding current of I2 kA are performed, wherein the sheet thickness ratio is defined as the ratio of the total steel sheet thickness to the thickness of a steel sheet on the thinner side (the thickness per sheet if the two steel sheets (1A, 1B) have the same thickness). The applied pressures P1 and P2 are set to a constant applied pressure of P = P1 = P2 through the first energizing process and the second energizing process. In addition, when an average sheet thickness of the steel sheets (1A, 1B) is assumed to be t mm, the applied pressure P is set in the range expressed by the formula {0.5 ≤ P ≤ 3.0t(1 / 3)}. The welding current I1 is set in the range of 30% to 90%, inclusive, of the welding current I2. The second energizing process is initiated within 0.1 s after the completion of the first energizing process.

To provide a steel-aluminum welded material and a spot welding method therefor having high weld strength.The steel-aluminum welded material 3 includes a steel material 1 and an aluminum material 2 having predetermined widths. The area of a nugget 5 of a spot-welded part is determined as a function of the thickness of the aluminum material 2, and the area of a part of the nugget 5 corresponding to a part having a thickness in a range between 0.5 and 10 μm of an interface reaction layer 6 is defined as a function of the thickness of the aluminum material 2.

When two high-strength steel sheets (1A, 1B) whose sheet thickness ratio={the sum of sheet thicknesses of the steel sheets} / {the sheet thickness of the thinner steel sheet (when they have the same thickness, the sheet thickness per one sheet)} is within a range of not less than 2 nor more than 5 and which both have tensile strength of not less than 780 MPa nor more than 1850 MPa are stacked to be subjected to resistance spot welding, a first welding step being pre-welding with a pressurizing force P1 kN and a welding current I1 kA and a second welding step being main welding with a pressurizing force P2 kN and a welding current I2 kA are performed, the pressurizing forces P1, P2 are set to a fixed pressurizing force P=P1=P2 all through the first welding step and the second welding step and are set within a range expressed by {0.5≤P≤3.0t(1 / 3)}, where t mm is an average sheet thickness of the steel sheets (1A, 1B), the welding current I1 is set within a range of not less than 30% nor more than 90% of the welding current I2, and the second welding step is started within 0.1 s after the first welding step is finished.

A method and system for estimating a driving point voltage of a resistance weld system. The method includes periodically sampling a supplied voltage and a supplied current of a system to obtain a plurality of sets of a sampled voltage value and a sampled current value. The sampled values are used for creating a volt time area of the sampled voltage, a current time area of the sampled current, and a current difference time area of the sampled current. The method further includes creating an estimated line resistance and an estimated line reactance of the system based on the first set of a sampled voltage value and a sampled current value and the second set of a sampled voltage value and a sampled current value. The volt time area, current time area, current difference time area, line resistance and line impedance are used for creating a driving point voltage area or waveform. The system includes circuitry for implementing the method for a resistance weld control.

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.