Abstract: A solid state welding apparatus comprises a pair of compression bars, a pair of electrodes disposed around the pair of compression bars, respectively, and a controller. The controller controls the pair of compression bars to cause a first load to act on each of the first and second workpieces, subsequently controls the pair of compression bars to subject compressive force to load removal to cause a second load smaller than the first load to act on the first and second workpieces, and subsequently passes a current through the pair of electrodes to remove an impurity on a metal surface.

Abstract: A method for joining dissimilar materials includes forming a first recess and a second recess by irradiating a surface of a first member with laser light, the first recess and the second recess being cut into the surface obliquely at angles different from each other, and joining the second member to the surface of the first member with a part of the second member engaging with each of the first recess and the second recess by melting the part of the second member lower in melting point than the first member to cause the part of the second member to flow into each of the first recess and the second recess and solidifying the part of the second member.

Abstract: An arc welding system of a consumable electrode type comprises: a wire feeding device that feeds welding wire from a wire feeding source to a welding torch; and a power supply device that supplies electric power between the welding wire fed to the welding torch and a base material, the system being configured to weld the base material by arc generated by the supplied electric power. The wire feeding device is provided with: an intermediate wire feeding source that is disposed between the wire feeding source and the welding torch and is configured to temporarily accommodate the welding wire fed from the wire feeding source and to feed the accommodated welding wire to the welding torch; a pull-out feeding part that feeds the welding wire at the wire feeding source to the intermediate wire feeding source; and a push-out feeding part that feeds the welding wire accommodated in the intermediate wire feeding source to the welding torch.

Abstract: An arc welding system of a consumable electrode type comprises: a wire feeding device that feeds welding wire from a wire feeding source to a welding torch; and a power supply device that supplies electric power between the welding wire fed to the welding torch and a base material, the system being configured to weld the base material by arc generated by the supplied electric power. The wire feeding device is provided with: an intermediate wire feeding source that is disposed between the wire feeding source and the welding torch and is configured to temporarily accommodate the welding wire fed from the wire feeding source and to feed the accommodated welding wire to the welding torch; a pull-out feeding part that feeds the welding wire at the wire feeding source to the intermediate wire feeding source; and a push-out feeding part that feeds the welding wire accommodated in the intermediate wire feeding source to the welding torch.

Abstract: To start consumable electrode arc welding, an initial current is supplied to a welding wire after causing the welding wire to contact a base material and retracting the welding wire from the base material. Thereby, an initial arc is generated. The welding wire is retracted continuously for an initial arc lift period Ti with the initial arc maintained. Afterwards, the initial arc is switched to a steady arc. A predetermined weld pool formation period Tp is set after the initial arc lift period Ti. In the weld pool formation period, a weld pool formation current greater than the initial current is supplied with the initial arc maintained and the welding wire is caused to proceed and fed to the base material. In the weld pool formation period, a weld pool is formed by the initial arc without allowing the welding wire to release droplets and contact the base material.

Abstract: An arc start control method in robot welding includes the steps of shorting a welding wire with a base metal, retracting a welding torch by a welding robot for taking the welding wire off the base metal to generate an initial arc, retracting the welding torch to a predetermined position with maintaining the initial arc maintained while applying an initial arc current smaller than a steady welding current during this initial arc period, and starting to feed the welding wire steadily and to supply the steady welding current so as to make a transition from the initial arc to a steady arc as well as starting to move the welding torch along a welding line. During a re-shorting prevention period which starts from a beginning of the initial arc period, a re-shorting prevention current which is larger than the initial arc current is applied in order to prevent re-shortening between the wire tip and the base metal right after the initial arc was generated. Thereafter, the initial arc current is applied.

Abstract: A control method for AC pulse arc welding performed upon application of cyclic AC welding current is provided. The welding current has a cycle including an electrode negative polarity period and an electrode positive polarity period subsequent to the electrode negative polarity period. In the control method, an electrode negative polarity base current and a subsequent electrode negative polarity peak current are applied during the electrode negative polarity period. The electrode negative polarity base current has an absolute value smaller than a first critical value, and the electrode negative polarity peak current has an absolute value greater than the first critical value. Then, an electrode positive polarity peak current is applied during the electrode positive polarity period. The electrode positive polarity peak current has a value greater than a second critical value.

Abstract: To start consumable electrode arc welding, an initial current is supplied to a welding wire after causing the welding wire to contact a base material and retracting the welding wire from the base material. In this manner, an initial arc is generated. The welding wire is retracted continuously for an initial arc lift period Ti with the initial arc maintained. Afterwards, the initial arc is switched to a steady arc. A predetermined weld pool formation period Tp is set after the initial arc lift period Ti. In the weld pool formation period, a weld pool formation current greater than the initial current is supplied with the initial arc maintained and the welding wire is caused to proceed and fed to the base material. In the weld pool formation period, a weld pool is formed by the initial arc without allowing the welding wire to release droplets and contact the base material. By this method, the initial arc is switched to the steady arc state after the weld pool has been formed.

Abstract: A control method for AC pulse arc welding performed upon application of cyclic AC welding current is provided. The welding current has a cycle including an electrode negative polarity period and an electrode positive polarity period subsequent to the electrode negative polarity period. In the control method, an electrode negative polarity base current and a subsequent electrode negative polarity peak current are applied during the electrode negative polarity period. The electrode negative polarity base current has an absolute value smaller than a first critical value, and the electrode negative polarity peak current has an absolute value greater than the first critical value. Then, an electrode positive polarity peak current is applied during the electrode positive polarity period. The electrode positive polarity peak current has a value greater than a second critical value.

Abstract: An arc start control method in robot welding includes the steps of shorting a welding wire with a base metal, retracting a welding torch by a welding robot for taking the welding wire off the base metal to generate an initial arc, retracting the welding torch to a predetermined position with maintaining the initial arc maintained while applying an initial arc current smaller than a steady welding current during this initial arc period, and starting to feed the welding wire steadily and to supply the steady welding current so as to make a transition from the initial arc to a steady arc as well as starting to move the welding torch along a welding line. During a re-shorting prevention period which starts from a beginning of the initial arc period, a re-shorting prevention current which is larger than the initial arc current is applied in order to prevent re-shortening between the wire tip and the base metal right after the initial arc was generated. Thereafter, the initial arc current is applied.

Abstract: A power supply for arc welding includes switching elements PTR, NTR for switching the polarity of the direct voltage from a power circuit PMC. The element PTR is connected in parallel to a series unit of a switching element TR1 and a resistor R1. Likewise, the element NTR is connected in parallel to a series unit of a switching element R2 and a resistor R2. A necking determination circuit ND determines whether a constriction occurs at the molten bridging portion between the welding wire and the base material. When the constriction occurs during the “electrode positive” mode, the switching element PTR is turned off, while the switching element TR1 is brought into the conduction state. When the constriction occurs during the “electrode negative” mode, the switching element NTR is turned off, while the switching element TR2 is brought into the conduction state.

Abstract: A power supply for arc welding includes switching elements PTR, NTR for switching the polarity of the direct voltage from a power circuit PMC. The element PTR is connected in parallel to a series unit of a switching element TR1 and a resistor R1. Likewise, the element NTR is connected in parallel to a series unit of a switching element R2 and a resistor R2. A necking determination circuit ND determines whether a constriction occurs at the molten bridging portion between the welding wire and the base material. When the constriction occurs during the “electrode positive” mode, the switching element PTR is turned off, while the switching element TR1 is brought into the conduction state. When the constriction occurs during the “electrode negative” mode, the switching element NTR is turned off, while the switching element TR2 is brought into the conduction state.

Abstract: An consumable electrode AC pulsed arc welding is performed by repeatedly executing a cycle of supplying a peak current Ip in an electrode positive polarity, then supplying an electrode negative current Ien in an electrode negative polarity and finally supplying a base current Ib in the electrode positive polarity. During a base current supply time, the rate of increase dVb/dt of the base voltage Vb is detected. Should the base voltage increase rate dVb/dt detected be larger than a predetermined determining value &Dgr;Vu, it means that the arc interruption is likely to occur and, therefore, since that timing, the peak current Ip for the subsequent cycle is supplied to thereby prevent the arc interruption from occurring.

Abstract: An arc length controlling method that is used in the practice of the pulsed welding in which welding is carried out by feeding an consumable electrode at a substantially constant speed while the pulse frequency f is set to a predetermined value. This method is carried out by effecting a welding after the counting time Tr and the target short-circuiting frequency Nr have been set, detecting the detected short-circuiting frequency Nk, and controlling the output voltage Vt to a value effective to allow the detected short-circuiting frequency Nk to be equal to the target short-circuiting frequency Nr.

Abstract: An MAG arc welding method and apparatus is capable of achieving a welding bead in a regular ripple pattern or in a suitable sectional form. The welding power source generates the first welding current I1 and a second welding current I2 larger than the first welding current. The wire melting speed is changed by switching between the first and the second welding currents. The welding method or apparatus according to the invention generates the first arc length more than 2 mm and the second arc length more than the first arc length and switches between both arc length at a switching frequency F of 0.5 to 25 Hz. The ratio of the second to the first welding currents is made to be in 1.03 to 1.20. In addition to a welding method to change the arc length by switching the first and the second welding currents at a constant wire feeding rate, the present welding method makes it possible to carry out the lap welding or butt welding even when there is a large gap.

Abstract: An MAG arc welding method and apparatus is capable of achieving a welding bead in a regular ripple pattern or in a suitable sectional form. The welding power source generates the first welding current I1 and a second welding current I2 larger than the first welding current. The wire melting speed is changed by switching between the first and the second welding currents. The welding method or apparatus according to the invention generates the first arc length more than 2 mm and the second arc length more than the first arc length and switches between both arc length at a switching frequency F of 0.5 to 25 Hz. The ratio of the second to the first welding currents is made to be in 1.03 to 1.20. In addition to a welding method to change the arc length by switching the first and the second welding currents at a constant wire feeding rate, the present welding method makes it possible to carry out the lap welding or butt welding even when there is a large gap.

Abstract: An MAG arc welding method and apparatus is capable of achieving a welding bead in a regular ripple pattern or in a suitable sectional form. The welding power source generates the first welding current I1 and a second welding current I2 larger than the first welding current. The wire melting speed is changed by switching between the first and the second welding currents. The welding method or apparatus according to the invention generates the first arc length more than 2 mm and the second arc length more than the first arc length and switches between both arc length at a switching frequency F of 0.5 to 25 Hz. The ratio of the second to the first welding currents is made to be in 1.03 to 1.20. In addition to a welding method to change the arc length by switching the first and the second welding currents at a constant wire feeding rate, the present welding method makes it possible to carry out the lap welding or butt welding even when there is a large gap.